Keep the new settings out of the network table

The settings file is written in the table's order, so settings of another
section between network.* entries wrote [network] twice, and the whole
file was then refused (defaults used). They now follow the network
settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

port/android/app/src/main/AndroidManifest.xml

@@ -19,6 +19,9 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
+    <!-- the voice chat in multiplayer (host_voice.c) -->
+    <uses-permission android:name="android.permission.RECORD_AUDIO" />
+    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
     <!-- installing a new version of the game (Updater) -->
     <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
 

port/android/app/src/main/java/com/halo/decomp/LauncherActivity.java

@@ -1,7 +1,10 @@
 package com.halo.decomp;
 
+import android.Manifest;
 import android.app.Activity;
 import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
 import android.graphics.Color;
 import android.net.Uri;
 import android.os.Bundle;
@@ -35,6 +38,7 @@ import java.nio.channels.FileChannel;
  */
 public class LauncherActivity extends Activity {
     private static final int PICK_IMAGE = 1;
+    private static final int ASK_MICROPHONE = 2;
 
     private File dataRoot;
     private TextView status;
@@ -53,12 +57,37 @@ public class LauncherActivity extends Activity {
         passOnHardwareId();
         passOnInvite(getIntent());
         if (haveData()) {
-            startGame();
+            if (!askForMicrophone())
+                startGame();
             return;
         }
         buildInterface();
     }
 
+    /**
+     * The voice chat's microphone (port/android/host/host_voice.c), asked
+     * for here, once, on this flat panel, before the game starts: in the
+     * game, the question would stop it. Returns true if it asked (the game
+     * starts on the answer).
+     */
+    private boolean askForMicrophone() {
+        SharedPreferences preferences = getSharedPreferences("launcher", MODE_PRIVATE);
+
+        if (checkSelfPermission(Manifest.permission.RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED
+            || preferences.getBoolean("asked_microphone", false))
+            return false;
+        preferences.edit().putBoolean("asked_microphone", true).apply();
+        requestPermissions(new String[] { Manifest.permission.RECORD_AUDIO }, ASK_MICROPHONE);
+        return true;
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] results) {
+        super.onRequestPermissionsResult(requestCode, permissions, results);
+        if (requestCode == ASK_MICROPHONE)
+            startGame();
+    }
+
     /**
      * An internet play invite link the app was opened with: the game
      * (port/linux/src/p2p.c) picks it up from join_link.txt, whether it is
@@ -111,6 +140,23 @@ public class LauncherActivity extends Activity {
             partial.delete();
     }
 
+    /**
+     * Whether the microphone may be used, for the game (port/linux/src/
+     * voice.c), which opens it only then: opening it otherwise would have
+     * Android ask in the middle of the game.
+     */
+    private void passOnMicrophonePermission() {
+        if (dataRoot == null)
+            return;
+        boolean granted =
+            checkSelfPermission(Manifest.permission.RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED;
+        try (OutputStream out = new FileOutputStream(new File(dataRoot, "microphone_permission.txt"))) {
+            out.write((granted ? "1" : "0").getBytes("UTF-8"));
+        } catch (java.io.IOException e) {
+            // the game then does without the microphone
+        }
+    }
+
     /** The game data, or the marker file of the VR self-test (host_xr.c). */
     private boolean haveData() {
         return dataRoot != null && (new File(dataRoot, "maps/ui.map").isFile() ||
@@ -118,6 +164,7 @@ public class LauncherActivity extends Activity {
     }
 
     private void startGame() {
+        passOnMicrophonePermission();
         startActivity(new Intent(this, HaloActivity.class));
         finish();
     }

port/android/guest/runtime/guest_host.h

@@ -131,6 +131,21 @@ int host_xr_copy_layer_array(int layer, unsigned int texture, int array_layer);
 /* darkens the eye images from their edges, strength 0..1 (0: off) */
 void host_xr_set_vignette(float strength);
 
+/* ---------- the voice chat (host_voice.c) */
+
+/* opens the voices' playback, and the microphone if asked (else closes
+it): their volume, and the level (0..1 of full scale) the microphone's
+sound must reach to be sent */
+int host_voice_start(int microphone, float volume, float threshold);
+void host_voice_stop(void);
+/* the microphone's speech since asked: Opus packets, each after a byte of
+its length; returns the bytes */
+int host_voice_take_packets(void *buffer, int size);
+/* the microphone's level (0..1000) */
+int host_voice_level(void);
+/* a speaker's packet (sequence numbered), played at these gains */
+void host_voice_play(int id, int sequence, const void *data, int length, float gain_left, float gain_right);
+
 /* ---------- Android */
 
 /* the storage directories the port uses, copied into buffer */

port/android/host/host_voice.c

@@ -0,0 +1,494 @@
+/*
+HOST_VOICE.C
+
+The voice chat's sound (the VR port's; port/linux/game/network_voice.c
+sends and receives it): the microphone, Opus, and the voices played. It
+runs here, natively, where SDL's audio threads may call it.
+
+- The microphone: SDL's default recording device, mono at 16 kHz, with
+  Android's voice communication preset (its echo cancelling and noise
+  suppression: SDL_HINT_ANDROID_AAUDIO_INPUT_PRESET). Every 20 ms of it
+  that is loud enough to be speech (or follows speech closely, VAD_HANGOVER)
+  is encoded (Opus, VOIP, 16 kbit/s) for the guest to send.
+- The voices: each speaker's packets, decoded as they come (a gap in their
+  numbers concealed by Opus's packet loss concealment), wait in the
+  speaker's buffer until JITTER_START of them is there, and are mixed, each
+  at the gains its latest packet was given (left and right: where the
+  speaker is), into a stream of their own.
+
+The devices are opened and closed on a thread of their own (voice_worker):
+opening a microphone can take a long while (an emulator's took a minute),
+which the game, whose clock the other machines follow, must not wait for.
+*/
+
+#include "host.h"
+
+#include <SDL3/SDL.h>
+#include <opus.h>
+#include <pthread.h>
+#include <string.h>
+
+enum
+{
+	VOICE_RATE = 16000,
+	FRAME_SAMPLES = VOICE_RATE / 50,
+	MAXIMUM_PACKET = 200,
+	MAXIMUM_SPEAKERS = 32,
+	/* a speaker's buffer: two seconds */
+	SPEAKER_BUFFER = VOICE_RATE * 2,
+	/* played from once this much is there, after silence */
+	JITTER_START = FRAME_SAMPLES * 3,
+	/* more than this behind: the oldest dropped */
+	JITTER_MAXIMUM = FRAME_SAMPLES * 15,
+	/* frames sent on after the voice drops below the threshold */
+	VAD_HANGOVER = 15,
+	BITRATE = 16000,
+};
+
+struct speaker
+{
+	int used;
+	int id;
+	OpusDecoder *decoder;
+	int has_sequence;
+	unsigned short sequence;
+	short buffer[SPEAKER_BUFFER];
+	int read;
+	int count;
+	int playing;
+	float gain_left;
+	float gain_right;
+	unsigned long long heard_ticks;
+};
+
+static struct
+{
+	SDL_Mutex *lock;
+	/* the devices wanted, which the worker opens and closes to match
+	(under worker_lock); the recording stream is read under it too */
+	pthread_mutex_t worker_lock;
+	pthread_cond_t worker_wake;
+	int worker_started;
+	int want_playback;
+	int want_recording;
+	/* the microphone */
+	SDL_AudioStream *recording;
+	OpusEncoder *encoder;
+	short frame[FRAME_SAMPLES];
+	int frame_count;
+	int hangover;
+	float threshold;
+	int level;
+	/* the voices */
+	SDL_AudioStream *playback;
+	struct speaker speakers[MAXIMUM_SPEAKERS];
+	float volume;
+} voice;
+
+static void voice_lock(void)
+{
+	if (!voice.lock)
+		voice.lock = SDL_CreateMutex();
+	SDL_LockMutex(voice.lock);
+}
+
+static void voice_unlock(void)
+{
+	SDL_UnlockMutex(voice.lock);
+}
+
+/* the voices mixed, as SDL asks for them (on its audio thread) */
+static void SDLCALL voice_playback_callback(void *userdata, SDL_AudioStream *stream, int additional, int total)
+{
+	short mixed[2 * 512];
+	(void)userdata;
+	(void)total;
+
+	while (additional > 0)
+	{
+		int frames = additional / 4;
+		int frame;
+		int index;
+
+		if (frames > 512)
+			frames = 512;
+		if (frames <= 0)
+			frames = 1;
+		memset(mixed, 0, sizeof(mixed));
+		voice_lock();
+		for (index = 0; index < MAXIMUM_SPEAKERS; index++)
+		{
+			struct speaker *speaker = &voice.speakers[index];
+
+			if (!speaker->used)
+				continue;
+			if (!speaker->playing && speaker->count >= JITTER_START)
+				speaker->playing = 1;
+			if (!speaker->playing)
+				continue;
+			for (frame = 0; frame < frames && speaker->count > 0; frame++)
+			{
+				float sample = (float)speaker->buffer[speaker->read] * voice.volume;
+				int left = mixed[2 * frame] + (int)(sample * speaker->gain_left);
+				int right = mixed[2 * frame + 1] + (int)(sample * speaker->gain_right);
+
+				mixed[2 * frame] = (short)(left > 32767 ? 32767 : left < -32768 ? -32768 : left);
+				mixed[2 * frame + 1] = (short)(right > 32767 ? 32767 : right < -32768 ? -32768 : right);
+				speaker->read = (speaker->read + 1) % SPEAKER_BUFFER;
+				speaker->count--;
+			}
+			/* (run dry: wait for enough again) */
+			if (!speaker->count)
+				speaker->playing = 0;
+		}
+		voice_unlock();
+		SDL_PutAudioStreamData(stream, mixed, frames * 4);
+		additional -= frames * 4;
+	}
+}
+
+static int voice_open_playback(void)
+{
+	SDL_AudioSpec spec;
+
+	if (voice.playback)
+		return 1;
+	spec.format = SDL_AUDIO_S16;
+	spec.channels = 2;
+	spec.freq = VOICE_RATE;
+	voice.playback = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &spec, voice_playback_callback,
+		NULL);
+	if (!voice.playback)
+	{
+		host_logf(HOST_LOG_WARN, "voice: cannot open the playback stream: %s", SDL_GetError());
+		return 0;
+	}
+	SDL_ResumeAudioStreamDevice(voice.playback);
+	return 1;
+}
+
+static SDL_AudioStream *voice_open_recording(void)
+{
+	SDL_AudioSpec spec;
+	SDL_AudioStream *recording;
+	int error;
+
+	if (!voice.encoder)
+	{
+		voice.encoder = opus_encoder_create(VOICE_RATE, 1, OPUS_APPLICATION_VOIP, &error);
+		if (!voice.encoder)
+		{
+			host_logf(HOST_LOG_WARN, "voice: cannot make the encoder (%d)", error);
+			return NULL;
+		}
+		opus_encoder_ctl(voice.encoder, OPUS_SET_BITRATE(BITRATE));
+		opus_encoder_ctl(voice.encoder, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));
+		opus_encoder_ctl(voice.encoder, OPUS_SET_INBAND_FEC(1));
+		opus_encoder_ctl(voice.encoder, OPUS_SET_PACKET_LOSS_PERC(10));
+	}
+	/* Android's voice communication preset: echo cancelling, noise
+	suppression (AAUDIO_INPUT_PRESET_VOICE_COMMUNICATION) */
+	SDL_SetHint(SDL_HINT_ANDROID_AAUDIO_INPUT_PRESET, "7");
+	spec.format = SDL_AUDIO_S16;
+	spec.channels = 1;
+	spec.freq = VOICE_RATE;
+	recording = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_RECORDING, &spec, NULL, NULL);
+	if (!recording)
+	{
+		host_logf(HOST_LOG_WARN, "voice: cannot open the microphone: %s", SDL_GetError());
+		return NULL;
+	}
+	SDL_ResumeAudioStreamDevice(recording);
+	host_logf(HOST_LOG_INFO, "voice: the microphone is open");
+	return recording;
+}
+
+static void voice_close_recording(void)
+{
+	SDL_AudioStream *recording;
+
+	pthread_mutex_lock(&voice.worker_lock);
+	recording = voice.recording;
+	voice.recording = NULL;
+	voice.level = 0;
+	pthread_mutex_unlock(&voice.worker_lock);
+	if (!recording)
+		return;
+	SDL_DestroyAudioStream(recording);
+	host_logf(HOST_LOG_INFO, "voice: the microphone is closed");
+}
+
+static void voice_close_playback(void)
+{
+	SDL_AudioStream *playback = voice.playback;
+
+	voice.playback = NULL;
+	if (playback)
+		SDL_DestroyAudioStream(playback);
+}
+
+/* opens and closes the devices as wanted, for as long as the app runs */
+static void *voice_worker(void *unused)
+{
+	(void)unused;
+	pthread_mutex_lock(&voice.worker_lock);
+	for (;;)
+	{
+		int want_playback = voice.want_playback;
+		int want_recording = voice.want_recording;
+		int have_playback = voice.playback != NULL;
+		int have_recording = voice.recording != NULL;
+
+		if (want_playback == have_playback && want_recording == have_recording)
+		{
+			pthread_cond_wait(&voice.worker_wake, &voice.worker_lock);
+			continue;
+		}
+		pthread_mutex_unlock(&voice.worker_lock);
+		if (want_recording && !have_recording)
+		{
+			/* (opened outside the lock, which the game reads it under) */
+			SDL_AudioStream *recording = voice_open_recording();
+
+			pthread_mutex_lock(&voice.worker_lock);
+			voice.recording = recording;
+			pthread_mutex_unlock(&voice.worker_lock);
+			/* (a microphone that will not open is not tried again until
+			wanted anew) */
+			if (!recording)
+			{
+				pthread_mutex_lock(&voice.worker_lock);
+				voice.want_recording = 0;
+				pthread_mutex_unlock(&voice.worker_lock);
+			}
+		}
+		else if (!want_recording && have_recording)
+		{
+			voice_close_recording();
+		}
+		if (want_playback && !have_playback)
+		{
+			if (!voice_open_playback())
+			{
+				pthread_mutex_lock(&voice.worker_lock);
+				voice.want_playback = 0;
+				pthread_mutex_unlock(&voice.worker_lock);
+			}
+		}
+		else if (!want_playback && have_playback)
+		{
+			voice_close_playback();
+		}
+		pthread_mutex_lock(&voice.worker_lock);
+	}
+	return NULL;
+}
+
+static void voice_want(int playback, int recording)
+{
+	if (!voice.worker_started)
+	{
+		voice.worker_started = 1;
+		pthread_mutex_init(&voice.worker_lock, NULL);
+		pthread_cond_init(&voice.worker_wake, NULL);
+		if (host_native_thread_create(voice_worker, NULL, 256 * 1024) != 0)
+		{
+			host_logf(HOST_LOG_WARN, "voice: cannot start the device thread");
+			return;
+		}
+	}
+	pthread_mutex_lock(&voice.worker_lock);
+	voice.want_playback = playback;
+	voice.want_recording = recording;
+	pthread_cond_signal(&voice.worker_wake);
+	pthread_mutex_unlock(&voice.worker_lock);
+}
+
+/* ---------- the guest's side */
+
+int host_voice_start(int microphone, float volume, float threshold)
+{
+	voice_lock();
+	voice.volume = volume < 0.0f ? 0.0f : volume > 4.0f ? 4.0f : volume;
+	voice.threshold = threshold;
+	voice_unlock();
+	voice_want(1, microphone);
+	return 1;
+}
+
+void host_voice_stop(void)
+{
+	int index;
+
+	voice_want(0, 0);
+	voice_lock();
+	for (index = 0; index < MAXIMUM_SPEAKERS; index++)
+	{
+		if (voice.speakers[index].decoder)
+			opus_decoder_destroy(voice.speakers[index].decoder);
+	}
+	memset(voice.speakers, 0, sizeof(voice.speakers));
+	voice_unlock();
+}
+
+int host_voice_take_packets(void *buffer, int size)
+{
+	unsigned char *out = buffer;
+	int used = 0;
+
+	if (!voice.worker_started)
+		return 0;
+	pthread_mutex_lock(&voice.worker_lock);
+	if (!voice.recording)
+	{
+		voice.frame_count = 0;
+		voice.hangover = 0;
+		pthread_mutex_unlock(&voice.worker_lock);
+		return 0;
+	}
+	for (;;)
+	{
+		int wanted = (FRAME_SAMPLES - voice.frame_count) * (int)sizeof(short);
+		int got = SDL_GetAudioStreamData(voice.recording, voice.frame + voice.frame_count, wanted);
+		double energy = 0.0;
+		int index;
+
+		if (got <= 0)
+			break;
+		voice.frame_count += got / (int)sizeof(short);
+		if (voice.frame_count < FRAME_SAMPLES)
+			break;
+		voice.frame_count = 0;
+		for (index = 0; index < FRAME_SAMPLES; index++)
+			energy += (double)voice.frame[index] * voice.frame[index];
+		energy = SDL_sqrt(energy / FRAME_SAMPLES) / 32768.0;
+		voice.level = (int)(energy * 1000.0);
+		if (energy >= voice.threshold)
+			voice.hangover = VAD_HANGOVER;
+		else if (voice.hangover > 0)
+			voice.hangover--;
+		else
+			continue;
+		if (used + 1 + MAXIMUM_PACKET > size)
+			continue;
+		{
+			int length = opus_encode(voice.encoder, voice.frame, FRAME_SAMPLES, out + used + 1, MAXIMUM_PACKET);
+
+			if (length > 0 && length < 256)
+			{
+				out[used] = (unsigned char)length;
+				used += 1 + length;
+			}
+		}
+	}
+	pthread_mutex_unlock(&voice.worker_lock);
+	return used;
+}
+
+int host_voice_level(void)
+{
+	return voice.level;
+}
+
+void host_voice_play(int id, int sequence, const void *data, int length, float gain_left, float gain_right)
+{
+	struct speaker *speaker = NULL;
+	struct speaker *oldest = NULL;
+	short decoded[FRAME_SAMPLES * 6];
+	int frames[4];
+	int frame_count = 0;
+	int index;
+
+	if (length <= 0 || length > MAXIMUM_PACKET)
+		return;
+	voice_lock();
+	for (index = 0; index < MAXIMUM_SPEAKERS && !speaker; index++)
+	{
+		if (voice.speakers[index].used && voice.speakers[index].id == id)
+			speaker = &voice.speakers[index];
+	}
+	if (!speaker)
+	{
+		for (index = 0; index < MAXIMUM_SPEAKERS && !speaker; index++)
+		{
+			if (!voice.speakers[index].used)
+				speaker = &voice.speakers[index];
+			else if (!oldest || voice.speakers[index].heard_ticks < oldest->heard_ticks)
+				oldest = &voice.speakers[index];
+		}
+		if (!speaker)
+			speaker = oldest;
+		if (!speaker->decoder)
+		{
+			int error;
+
+			speaker->decoder = opus_decoder_create(VOICE_RATE, 1, &error);
+			if (!speaker->decoder)
+			{
+				voice_unlock();
+				return;
+			}
+		}
+		else
+		{
+			opus_decoder_ctl(speaker->decoder, OPUS_RESET_STATE);
+		}
+		speaker->used = 1;
+		speaker->id = id;
+		speaker->has_sequence = 0;
+		speaker->read = speaker->count = 0;
+		speaker->playing = 0;
+	}
+	speaker->heard_ticks = SDL_GetTicks();
+	speaker->gain_left = gain_left;
+	speaker->gain_right = gain_right;
+	{
+		unsigned short number = (unsigned short)sequence;
+
+		if (speaker->has_sequence)
+		{
+			short gap = (short)(number - speaker->sequence);
+
+			/* (late, or again: dropped) */
+			if (gap <= 0)
+			{
+				voice_unlock();
+				return;
+			}
+			/* (lost ones: concealed, a few) */
+			if (gap > 1 && gap <= 4 && speaker->count > 0)
+			{
+				int missing;
+
+				for (missing = 1; missing < gap && frame_count < 3; missing++)
+				{
+					frames[frame_count] = opus_decode(speaker->decoder, NULL, 0, decoded + frame_count * FRAME_SAMPLES,
+						FRAME_SAMPLES, 0);
+					frame_count++;
+				}
+			}
+		}
+		speaker->has_sequence = 1;
+		speaker->sequence = number;
+	}
+	frames[frame_count] = opus_decode(speaker->decoder, data, length, decoded + frame_count * FRAME_SAMPLES,
+		FRAME_SAMPLES * 2, 0);
+	frame_count++;
+	for (index = 0; index < frame_count; index++)
+	{
+		int sample;
+
+		for (sample = 0; sample < frames[index] && sample < FRAME_SAMPLES * 2; sample++)
+		{
+			if (speaker->count >= JITTER_MAXIMUM)
+			{
+				speaker->read = (speaker->read + 1) % SPEAKER_BUFFER;
+				speaker->count--;
+			}
+			speaker->buffer[(speaker->read + speaker->count) % SPEAKER_BUFFER] =
+				decoded[index * FRAME_SAMPLES + sample];
+			speaker->count++;
+		}
+	}
+	voice_unlock();
+}

port/android/host_imports.list

@@ -58,6 +58,11 @@ host_xr_copy_layer_region
 host_xr_end_frame
 host_xr_haptic
 host_xr_set_vignette
+host_voice_start
+host_voice_stop
+host_voice_take_packets
+host_voice_level
+host_voice_play
 host_xr_copy_layer_array
 host_android_path
 

port/linux/game/network_distributed.c

@@ -3051,6 +3051,7 @@ void network_distributed_new_game(
 	network_objects_new_game();
 	network_damage_new_game();
 	network_vr_new_game();
+	network_voice_new_game();
 }
 
 /* after each tick (game_time.c) */
@@ -3093,6 +3094,7 @@ void network_distributed_tick(
 		distributed_statistics_due = FALSE;
 		distributed_host_send_players();
 		network_vr_tick();
+		network_voice_tick();
 		distributed_send_pickups();
 		if (game_time_get() % GAME_STATE_INTERVAL_TICKS == 0)
 			distributed_send_game_state(NONE);
@@ -3102,6 +3104,7 @@ void network_distributed_tick(
 		distributed_note_own_positions();
 		distributed_client_send_inputs();
 		network_vr_tick();
+		network_voice_tick();
 		distributed_client_send_predictions();
 		network_objects_client_tick();
 		network_damage_client_tick();
@@ -3577,6 +3580,7 @@ void network_distributed_handle_message(
 	case _distributed_message_client_ready: entry_size = 0; break;
 	case _distributed_message_client_identity: entry_size = sizeof(struct distributed_client_identity); break;
 	case _distributed_message_vr_poses: entry_size = network_vr_entry_size(); break;
+	case _distributed_message_voice: entry_size = network_voice_entry_size(); break;
 	case _distributed_message_damage_events:
 	case _distributed_message_hit_reports: entry_size = network_damage_entry_size(header.type); break;
 	default: entry_size = network_objects_entry_size(header.type); break;
@@ -3590,6 +3594,16 @@ void network_distributed_handle_message(
 
 	/* (each kind from the host, or from a client; a VR player's hands
 	both ways) */
+	if (header.type == _distributed_message_voice)
+	{
+		if (machine_index == NONE ? game_connection() != _game_connection_network_client :
+				game_connection() != _game_connection_network_server)
+		{
+			return;
+		}
+		network_voice_handle(machine_index, message, size);
+		return;
+	}
 	if (header.type == _distributed_message_vr_poses)
 	{
 		if (machine_index == NONE ? game_connection() != _game_connection_network_client :

port/linux/game/network_distributed.h

@@ -66,6 +66,10 @@ enum
 	the host, the host's of the others to each client (unreliable;
 	network_vr.c). Last, so that a build without it drops it. */
 	_distributed_message_vr_poses,
+	/* (the VR port's) a player's speech, every tick while they speak: a
+	client's own to the host, the host's and the other clients' to each
+	client (unreliable; network_voice.c) */
+	_distributed_message_voice,
 
 	NUMBER_OF_DISTRIBUTED_MESSAGES
 };
@@ -236,4 +240,10 @@ void network_vr_tick(void);
 word network_vr_entry_size(void);
 void network_vr_handle_poses(long machine_index, void const *entries, short count);
 
+/* the voice chat (network_voice.c) */
+void network_voice_new_game(void);
+void network_voice_tick(void);
+word network_voice_entry_size(void);
+void network_voice_handle(long machine_index, void const *message, word size);
+
 #endif // __NETWORK_DISTRIBUTED_H

port/linux/game/network_voice.c

@@ -0,0 +1,326 @@
+/*
+NETWORK_VOICE.C
+
+The voice chat (the VR port's): an extension of the distributed netcode
+(port/linux/NETCODE.md, network_distributed.c), as the VR players' hands
+are (network_vr.c).
+
+- Every tick, a machine sends what its microphone heard of its player's
+  speech (halo_voice.h: Opus packets of 20 ms, only while they speak) in
+  _distributed_message_voice (unreliable): a client to the host, which
+  plays it and passes it on to its other clients; the host its own to
+  every client.
+- A machine plays each speaker's voice from where they are: a teammate
+  (in a game of teams) over the radio, as loud anywhere and only a little
+  to the side they are on; anyone else as near as they are (no further off
+  than VOICE_RANGE), from their side. A speaker with no unit (dead) is
+  heard over the radio by their team, and not by the rest.
+
+A machine that does not know the message (a build without this, of the same
+network version) drops it, as it drops any type past its own.
+*/
+
+#include "cseries.h"
+#include "game/game.h"
+#include "game/game_engine.h"
+#include "game/players.h"
+#include "units/units.h"
+#include "network_distributed.h"
+#include "halo_voice.h"
+#include "halo_vr.h"
+
+#include <math.h>
+
+void platform_log(char const *format, ...);
+
+/* ---------- constants */
+
+enum
+{
+	/* an entry: the speaker, its sequence number and the packet's length,
+	and the packet */
+	VOICE_ENTRY_HEADER = 4,
+	VOICE_MAXIMUM_PACKET = 200,
+	VOICE_MAXIMUM_TAKEN = 1024,
+};
+
+/* how far off someone not on the radio is heard (world units: 60 metres) */
+#define VOICE_RANGE 20.0f
+/* how far to the side a voice is put: on the radio, and near */
+#define VOICE_RADIO_PAN 0.3f
+#define VOICE_NEAR_PAN 0.8f
+
+/* ---------- globals */
+
+static struct
+{
+	boolean active;
+	word sequence;
+	long sent;
+	long played;
+	long log_time;
+} network_voice;
+
+/* ---------- private code */
+
+static boolean network_voice_in_network_game(
+	void)
+{
+	short connection = game_connection();
+
+	return (connection == _game_connection_network_server || connection == _game_connection_network_client) &&
+		game_in_progress();
+}
+
+/* where a player's head is, and whether they have a unit */
+static boolean network_voice_player_head(
+	struct player_datum const *player,
+	real_point3d *head)
+{
+	long unit_index = distributed_living_unit(player);
+
+	if (unit_index == NONE)
+		return FALSE;
+	unit_get_camera_position(unit_index, head);
+	return TRUE;
+}
+
+/* the gains a speaker is heard at here (FALSE: not heard) */
+static boolean network_voice_gains(
+	struct player_datum const *speaker,
+	real *left,
+	real *right)
+{
+	long listener_index = local_player_get_player_index(0);
+	struct player_datum *listener = listener_index != NONE ? player_try_and_get(listener_index) : NULL;
+	boolean teammate = listener && game_engine_has_teams() && listener->team_index == speaker->team_index;
+	real_point3d speaker_head;
+	real_point3d listener_head;
+	real gain = 1.0f;
+	real pan = 0.0f;
+
+	if (!listener)
+		return FALSE;
+	if (!network_voice_player_head(speaker, &speaker_head))
+	{
+		/* (dead: on the radio, to the team) */
+		if (!teammate)
+			return FALSE;
+		*left = *right = 1.0f;
+		return TRUE;
+	}
+	if (network_voice_player_head(listener, &listener_head))
+	{
+		real dx = speaker_head.x - listener_head.x;
+		real dy = speaker_head.y - listener_head.y;
+		real dz = speaker_head.z - listener_head.z;
+		real distance = (real)sqrt(dx * dx + dy * dy + dz * dz);
+		real flat = (real)sqrt(dx * dx + dy * dy);
+		float look[3];
+		real forward_x;
+		real forward_y;
+		real length;
+		struct unit_datum *unit = unit_try_and_get(distributed_living_unit(listener));
+
+		/* (where the listener looks: the head, in VR) */
+		if (halo_vr_look_vector(0, look))
+		{
+			forward_x = look[0];
+			forward_y = look[1];
+		}
+		else
+		{
+			forward_x = unit ? unit->unit.looking_vector.i : 1.0f;
+			forward_y = unit ? unit->unit.looking_vector.j : 0.0f;
+		}
+		length = (real)sqrt(forward_x * forward_x + forward_y * forward_y);
+		if (length > 0.0001f && flat > 0.0001f)
+		{
+			/* (the right: forward turned clockwise) */
+			pan = (dx * forward_y - dy * forward_x) / (flat * length);
+		}
+		if (!teammate)
+		{
+			gain = 1.0f - distance / VOICE_RANGE;
+			if (gain <= 0.0f)
+				return FALSE;
+			gain *= gain;
+		}
+		pan *= teammate ? VOICE_RADIO_PAN : VOICE_NEAR_PAN;
+	}
+	else if (!teammate)
+	{
+		/* (the listener dead: the others as from where the body is not:
+		not at all) */
+		return FALSE;
+	}
+	*left = gain * (pan > 0.0f ? 1.0f - pan : 1.0f);
+	*right = gain * (pan < 0.0f ? 1.0f + pan : 1.0f);
+	return TRUE;
+}
+
+static void network_voice_play_entries(
+	byte const *entries,
+	byte const *end,
+	short count,
+	long machine_index)
+{
+	short index;
+
+	for (index = 0; index < count && entries + VOICE_ENTRY_HEADER <= end; index++)
+	{
+		byte player_byte = entries[0];
+		word sequence = (word)(entries[1] | entries[2] << 8);
+		short length = entries[3];
+		long player_index;
+		struct player_datum *player;
+		real left;
+		real right;
+
+		if (length <= 0 || entries + VOICE_ENTRY_HEADER + length > end)
+			break;
+		player_index = distributed_player_from_byte(player_byte);
+		player = player_index != NONE ? player_try_and_get(player_index) : NULL;
+		/* (the host: only a client's own players') */
+		if (player && (machine_index == NONE || distributed_machine_has_player(machine_index, player_byte)) &&
+			player->local_player_index == NONE && network_voice_gains(player, &left, &right))
+		{
+			halo_voice_play(player_byte, sequence, entries + VOICE_ENTRY_HEADER, length, left, right);
+			network_voice.played++;
+		}
+		entries += VOICE_ENTRY_HEADER + length;
+	}
+}
+
+/* ---------- public code */
+
+void network_voice_new_game(
+	void)
+{
+	network_voice.sequence = 0;
+}
+
+word network_voice_entry_size(
+	void)
+{
+	return VOICE_ENTRY_HEADER;
+}
+
+/* after each tick (network_distributed_tick): this machine's speech sent */
+void network_voice_tick(
+	void)
+{
+	struct
+	{
+		struct distributed_message_header header;
+		byte entries[VOICE_MAXIMUM_TAKEN + 64];
+	} message;
+	byte taken[VOICE_MAXIMUM_TAKEN];
+	long player_index = local_player_get_player_index(0);
+	long size;
+	long offset = 0;
+	long used = 0;
+	short count = 0;
+
+	if (!network_voice_in_network_game() || !halo_voice_enabled())
+	{
+		if (network_voice.active)
+		{
+			network_voice.active = FALSE;
+			halo_voice_end();
+		}
+		return;
+	}
+	if (!network_voice.active)
+	{
+		network_voice.active = TRUE;
+		halo_voice_begin();
+	}
+	if (game_time_get() - network_voice.log_time >= 150 && (network_voice.sent || network_voice.played))
+	{
+		platform_log("voice: sent %ld, played %ld packets (in 150 ticks)", network_voice.sent, network_voice.played);
+		network_voice.sent = network_voice.played = 0;
+		network_voice.log_time = game_time_get();
+	}
+	size = halo_voice_take(taken, sizeof(taken));
+	if (player_index == NONE)
+		return;
+	while (offset < size)
+	{
+		short length = taken[offset];
+
+		if (length <= 0 || offset + 1 + length > size || length > VOICE_MAXIMUM_PACKET)
+			break;
+		if (used + VOICE_ENTRY_HEADER + length > (long)sizeof(message.entries))
+			break;
+		message.entries[used] = distributed_player_to_byte(player_index);
+		message.entries[used + 1] = (byte)(network_voice.sequence & 0xFF);
+		message.entries[used + 2] = (byte)(network_voice.sequence >> 8);
+		message.entries[used + 3] = (byte)length;
+		csmemcpy(message.entries + used + VOICE_ENTRY_HEADER, taken + offset + 1, length);
+		used += VOICE_ENTRY_HEADER + length;
+		offset += 1 + length;
+		network_voice.sequence++;
+		count++;
+	}
+	if (!count)
+		return;
+	network_voice.sent += count;
+	distributed_send(&message, _distributed_message_voice, count, (word)(sizeof(message.header) + used),
+		game_connection() == _game_connection_network_server ? _distributed_to_clients : _distributed_to_host);
+}
+
+/* a machine's speech: on the host a client's, played and passed on to the
+other clients; on a client the host's of any other */
+void network_voice_handle(
+	long machine_index,
+	void const *message,
+	word size)
+{
+	struct distributed_message_header header;
+	byte const *entries = (byte const *)message + sizeof(header);
+	byte const *end = (byte const *)message + size;
+
+	if (!halo_voice_enabled() || !network_voice.active)
+		return;
+	csmemcpy(&header, message, sizeof(header));
+	network_voice_play_entries(entries, end, header.count, machine_index);
+	if (machine_index != NONE)
+	{
+		long machine_indices[HALO_PORT_MAXIMUM_NETWORK_MACHINES];
+		short machine_count = distributed_client_machines(machine_indices, HALO_PORT_MAXIMUM_NETWORK_MACHINES);
+		short number;
+		struct
+		{
+			struct distributed_message_header header;
+			byte entries[VOICE_MAXIMUM_TAKEN + 64];
+		} relayed;
+		word entries_size = (word)(end - entries);
+
+		byte const *entry = entries;
+		short index;
+
+		/* (only the sender's own players' speech is passed on, whole) */
+		if (entries_size < VOICE_ENTRY_HEADER || entries_size > sizeof(relayed.entries))
+			return;
+		for (index = 0; index < header.count; index++)
+		{
+			if (entry + VOICE_ENTRY_HEADER > end || entry[3] == 0 || entry + VOICE_ENTRY_HEADER + entry[3] > end ||
+				!distributed_machine_has_player(machine_index, entry[0]))
+			{
+				return;
+			}
+			entry += VOICE_ENTRY_HEADER + entry[3];
+		}
+		if (entry != end)
+			return;
+		for (number = 0; number < machine_count; number++)
+		{
+			if (machine_indices[number] == machine_index)
+				continue;
+			csmemcpy(relayed.entries, entries, entries_size);
+			distributed_send_to_machine(machine_indices[number], &relayed, _distributed_message_voice, header.count,
+				(word)(sizeof(relayed.header) + entries_size));
+		}
+	}
+}

port/linux/game/network_vr.c

@@ -49,8 +49,13 @@ enum
 
 /* how long a player's hands drive them after the last came (ticks): longer
 and they are driven as before (the hands stopped coming: the player left
-VR, or the network) */
+VR, or the network). Where the weapon aims and fires from is held a
+second, over the gaps of a network that delivers in bursts (as the input
+the netcode relays is); a grenade held, only a third of one, so that it
+does not hang in the hand after the hand let go. The host relays only
+hands as fresh as that. */
 #define VR_POSE_FRESH_TICKS 10
+#define VR_AIM_HOLD_TICKS 30
 /* how long a throw is sent after it (ticks), and taken after it came */
 #define VR_THROW_TICKS 30
 /* offsets from the unit's camera: in 1/4096 of a world unit, no further
@@ -152,7 +157,8 @@ static boolean network_vr_direction_unpack(
 
 /* a player of another machine whose hands came lately, or NULL */
 static struct network_vr_player *network_vr_remote_player(
-	long player_index)
+	long player_index,
+	long fresh_ticks)
 {
 	struct network_vr_player *vr_player;
 	long absolute_index;
@@ -163,7 +169,7 @@ static struct network_vr_player *network_vr_remote_player(
 	if (absolute_index < 0 || absolute_index >= MAXIMUM_TRACKED_PLAYERS)
 		return NULL;
 	vr_player = &network_vr_players[absolute_index];
-	if (!vr_player->valid || game_time_get() - vr_player->received_time > VR_POSE_FRESH_TICKS ||
+	if (!vr_player->valid || game_time_get() - vr_player->received_time > fresh_ticks ||
 		game_time_get() < vr_player->received_time)
 	{
 		return NULL;
@@ -395,7 +401,7 @@ void network_vr_handle_poses(
 
 int halo_vr_network_aim(long player_index, float vector[3])
 {
-	struct network_vr_player *vr_player = network_vr_remote_player(player_index);
+	struct network_vr_player *vr_player = network_vr_remote_player(player_index, VR_AIM_HOLD_TICKS);
 	real_vector3d aim;
 
 	if (!vr_player || !TEST_FLAG(vr_player->pose.flags, _vr_pose_aim_bit) ||
@@ -412,7 +418,7 @@ int halo_vr_network_aim(long player_index, float vector[3])
 
 int halo_vr_network_weapon_origin(long player_index, long unit_index, float origin[3])
 {
-	struct network_vr_player *vr_player = network_vr_remote_player(player_index);
+	struct network_vr_player *vr_player = network_vr_remote_player(player_index, VR_AIM_HOLD_TICKS);
 	real_vector3d offset;
 	real_point3d camera;
 
@@ -430,7 +436,7 @@ int halo_vr_network_weapon_origin(long player_index, long unit_index, float orig
 
 int halo_vr_network_grenade_held(long player_index)
 {
-	struct network_vr_player *vr_player = network_vr_remote_player(player_index);
+	struct network_vr_player *vr_player = network_vr_remote_player(player_index, VR_POSE_FRESH_TICKS);
 
 	return vr_player && TEST_FLAG(vr_player->pose.flags, _vr_pose_grenade_held_bit);
 }
@@ -438,7 +444,7 @@ int halo_vr_network_grenade_held(long player_index)
 int halo_vr_network_grenade_throw(long player_index, long unit_index, float origin[3], float direction[3],
 	float *strength)
 {
-	struct network_vr_player *vr_player = network_vr_remote_player(player_index);
+	struct network_vr_player *vr_player = network_vr_remote_player(player_index, VR_THROW_TICKS);
 	real_vector3d offset;
 	real_vector3d way;
 	real_point3d camera;

port/linux/include/halo_voice.h

@@ -0,0 +1,31 @@
+/*
+HALO_VOICE.H
+
+The voice chat's sound for the game (port/linux/src/voice.c: on Android the
+host's microphone, Opus and mixer, port/android/host/host_voice.c; elsewhere
+nothing). port/linux/game/network_voice.c sends and receives it.
+*/
+
+#ifndef __HALO_VOICE_H
+#define __HALO_VOICE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* whether the voice chat is on (voice.enabled) */
+int halo_voice_enabled(void);
+/* starts playing voices, and the microphone if voice.microphone; stops */
+int halo_voice_begin(void);
+void halo_voice_end(void);
+/* the microphone's speech since asked: Opus packets, each after a byte of
+its length; returns the bytes */
+int halo_voice_take(void *buffer, int size);
+/* a speaker's packet, played at these gains (left, right) */
+void halo_voice_play(int speaker, int sequence, const void *data, int length, float left, float right);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

port/linux/src/p2p.c

@@ -331,6 +331,8 @@ static struct
 	unsigned char join_host_hash[P2P_KEY_HASH_SIZE];
 	unsigned char join_token[P2P_TOKEN_SIZE];
 	unsigned long join_time;
+	/* how the latest join goes, for the menus (p2p_join_state) */
+	int join_state;
 
 	char clipboard[P2P_LINK_SIZE];
 	int has_clipboard;
@@ -840,6 +842,12 @@ static void drop_peer(struct peer *peer, const char *reason)
 	struct retired_session *retired = &p2p.retired[p2p.retired_next++ % MAXIMUM_RETIRED_SESSIONS];
 	int ask_again = p2p.joining && peer->is_host && !memcmp(peer->identifier, p2p.join_host, P2P_IDENTIFIER_SIZE);
 
+	if (peer->is_host && !memcmp(peer->identifier, p2p.join_host, P2P_IDENTIFIER_SIZE) &&
+		p2p.join_state != P2P_JOIN_NONE)
+	{
+		p2p.join_state = peer->connected ? P2P_JOIN_LOST : P2P_JOIN_BLOCKED;
+	}
+
 	platform_log("Internet play: %s %s: %s", peer->is_host ? "host" : "player", peer->name, reason);
 	if (peer->connected)
 	{
@@ -1029,6 +1037,8 @@ static void peer_heard(struct peer *peer, unsigned long address, unsigned short
 			address_text(address, port, text));
 		if (peer->is_host)
 		{
+			if (!memcmp(p2p.join_host, peer->identifier, P2P_IDENTIFIER_SIZE) && p2p.join_state != P2P_JOIN_NONE)
+				p2p.join_state = P2P_JOIN_CONNECTED;
 			if (p2p.joining && !memcmp(p2p.join_host, peer->identifier, P2P_IDENTIFIER_SIZE))
 			{
 				p2p.joining = 0;
@@ -2298,6 +2308,7 @@ static int join_invite(const char *text)
 	memcpy(p2p.join_host_hash, hash, sizeof(hash));
 	memcpy(p2p.join_token, token, sizeof(token));
 	p2p.join_requested = 1;
+	p2p.join_state = P2P_JOIN_REACHING;
 	return 1;
 }
 
@@ -2314,10 +2325,93 @@ int p2p_join_invite(const char *text)
 	return result > 0;
 }
 
+int p2p_join_code(char *text, int size)
+{
+	int result;
+
+	pthread_mutex_lock(&p2p_lock);
+	result = p2p.running && p2p_code_hosted(text, size);
+	pthread_mutex_unlock(&p2p_lock);
+	return result;
+}
+
+int p2p_join_with_code(const char *typed)
+{
+	int result;
+
+	pthread_mutex_lock(&p2p_lock);
+	result = p2p.running && p2p_code_look_up(typed);
+	pthread_mutex_unlock(&p2p_lock);
+	return result;
+}
+
+int p2p_join_code_status(void)
+{
+	int status;
+
+	pthread_mutex_lock(&p2p_lock);
+	status = p2p.running ? p2p_code_status() : P2P_CODE_OFFLINE;
+	pthread_mutex_unlock(&p2p_lock);
+	return status;
+}
+
+void p2p_set_public_game(int public_game)
+{
+	pthread_mutex_lock(&p2p_lock);
+	p2p_list_set_public(public_game);
+	pthread_mutex_unlock(&p2p_lock);
+}
+
+int p2p_public_game(void)
+{
+	int result;
+
+	pthread_mutex_lock(&p2p_lock);
+	result = p2p_list_public();
+	pthread_mutex_unlock(&p2p_lock);
+	return result;
+}
+
+void p2p_set_game_description(const char *name, const char *map, const char *mode, int players,
+	int maximum_players)
+{
+	pthread_mutex_lock(&p2p_lock);
+	p2p_list_set_description(name, map, mode, players, maximum_players);
+	pthread_mutex_unlock(&p2p_lock);
+}
+
+int p2p_public_games(struct p2p_public_game *games, int maximum)
+{
+	int count;
+
+	pthread_mutex_lock(&p2p_lock);
+	count = p2p.running ? p2p_list_games(games, maximum) : 0;
+	pthread_mutex_unlock(&p2p_lock);
+	return count;
+}
+
+int p2p_join_state(void)
+{
+	int state;
+
+	pthread_mutex_lock(&p2p_lock);
+	state = p2p.running ? p2p.join_state : P2P_JOIN_NONE;
+	pthread_mutex_unlock(&p2p_lock);
+	return state;
+}
+
+void p2p_join_code_clear_status(void)
+{
+	pthread_mutex_lock(&p2p_lock);
+	p2p_code_clear_status();
+	pthread_mutex_unlock(&p2p_lock);
+}
+
 void p2p_invite_received(const char *text)
 {
-	/* (an older version's is logged as such) */
-	if (!join_invite(text))
+	/* (an older version's is logged as such; a join code is looked up,
+	p2p_code.c) */
+	if (!join_invite(text) && !p2p_code_look_up(text))
 		platform_log("Internet play: that is not an invite");
 }
 
@@ -2343,6 +2437,8 @@ static void update_joining(void)
 	{
 		p2p.joining = 0;
 		p2p_signal_stop_joining();
+		if (p2p.join_state == P2P_JOIN_REACHING)
+			p2p.join_state = P2P_JOIN_NO_ANSWER;
 		platform_log("Internet play: no answer from the invite's host; it may have stopped hosting or quit");
 	}
 }
@@ -2382,6 +2478,14 @@ static void update_hosting(void)
 		p2p.stun_started = 1;
 		p2p_signal_start();
 		p2p_signal_host(p2p.token);
+		{
+			/* (and a join code for it, p2p_code.c) */
+			unsigned char bytes[P2P_KEY_HASH_SIZE + P2P_TOKEN_SIZE];
+
+			p2p_key_hash(p2p_public_key(), bytes);
+			memcpy(bytes + P2P_KEY_HASH_SIZE, p2p.token, P2P_TOKEN_SIZE);
+			p2p_code_host(bytes);
+		}
 		platform_log("Internet play: hosting. Invite players with this link (it only works while this "
 			"copy of the game runs): %s", p2p.invite);
 		if (!p2p.invite_copied)
@@ -2396,6 +2500,7 @@ static void update_hosting(void)
 	{
 		p2p.hosting = 0;
 		p2p_signal_stop_hosting();
+		p2p_code_stop_hosting();
 		p2p_discord_set_hosting(NULL, 0, 0);
 	}
 	if (p2p.hosting)

port/linux/src/p2p.h

@@ -26,6 +26,61 @@ int p2p_hand_off_invite(void);
 words around it. Returns nonzero if it held an invite */
 int p2p_join_invite(const char *text);
 
+/* Join codes (p2p_code.c): the hosted game's code as XXXX-XXXX (0 if
+none); looking a typed one up, which then joins as its invite does (0 if
+it is not a code, or internet play is off); and how the look up goes */
+enum
+{
+	P2P_CODE_IDLE,
+	P2P_CODE_LOOKING,
+	P2P_CODE_FOUND,
+	P2P_CODE_NOT_FOUND,
+	P2P_CODE_INVALID,
+	P2P_CODE_OWN,
+	P2P_CODE_OFFLINE,
+};
+int p2p_join_code(char *text, int size);
+int p2p_join_with_code(const char *typed);
+int p2p_join_code_status(void);
+void p2p_join_code_clear_status(void);
+/* how the latest join of an invite or code goes (the VR port's, for the
+menus): reaching the host, connected (its game is in the system link list),
+or why not */
+enum
+{
+	P2P_JOIN_NONE,
+	P2P_JOIN_REACHING,
+	P2P_JOIN_CONNECTED,
+	P2P_JOIN_NO_ANSWER,
+	P2P_JOIN_BLOCKED,
+	P2P_JOIN_LOST,
+};
+int p2p_join_state(void);
+
+/* Public games (p2p_list.c): the hosted game listed for anyone or not, and
+what it is (the game's server, as it changes); and the games others list,
+joined by their codes (p2p_join_with_code) */
+enum
+{
+	P2P_PUBLIC_NAME_SIZE = 16,
+	P2P_PUBLIC_MAP_SIZE = 32,
+	P2P_PUBLIC_MODE_SIZE = 24,
+};
+struct p2p_public_game
+{
+	char name[P2P_PUBLIC_NAME_SIZE];
+	char map[P2P_PUBLIC_MAP_SIZE];
+	char mode[P2P_PUBLIC_MODE_SIZE];
+	char code[12];
+	int players;
+	int maximum_players;
+};
+void p2p_set_public_game(int public_game);
+int p2p_public_game(void);
+void p2p_set_game_description(const char *name, const char *map, const char *mode, int players,
+	int maximum_players);
+int p2p_public_games(struct p2p_public_game *games, int maximum);
+
 /* this machine's identifier, which its XNADDR carries (6 bytes) */
 const unsigned char *p2p_identifier(void);
 /* the address the game reaches the machine with this identifier at, if it

port/linux/src/p2p_code.c

@@ -0,0 +1,317 @@
+/*
+P2P_CODE.C
+
+Join codes (the VR port's): a short code that stands for a hosted game's
+invite (p2p.c), for a player who cannot pass a link on, as in a headset,
+where a link is not copied out and 64 hex digits are not typed in.
+
+- A host makes a code when it starts hosting: 8 characters of Crockford's
+  base 32 (40 bits), shown as XXXX-XXXX (ui_join_code.c draws it in the
+  lobby). It lasts while the host hosts.
+- From the code come a topic and a key (PBKDF2-HMAC-SHA256, slow on
+  purpose: CODE_KDF_ITERATIONS). The host listens on the topic through the
+  signalling brokers (p2p_signal.c). A player who types the code asks
+  there (ASK: a nonce), and the host answers with its invite, sealed with
+  the key, with the nonce (INVITE); the asker opens it and joins as an
+  invite link would.
+- The brokers, and anyone who watches them, see the topic, but cannot tell
+  the code from it, or open the answer, short of working the slow
+  derivation out for codes until one fits; a code is guessed at one in 2^40
+  of them. An asker who has the code has the invite, as one given the link
+  has: it joins as anyone invited does.
+
+A build without this (another of the same network version) has no codes,
+and its players join with the link (which the host still logs and copies).
+*/
+
+#include "platform.h"
+#include "posix.h"
+#include "p2p_internal.h"
+
+#include <stdio.h>
+#include <string.h>
+
+enum
+{
+	CODE_SYMBOLS = 8,
+	CODE_KDF_ITERATIONS = 20000,
+	CODE_NONCE_SIZE = 8,
+	CODE_INVITE_SIZE = P2P_KEY_HASH_SIZE + P2P_TOKEN_SIZE,
+	CODE_MESSAGE_VERSION = 1,
+	/* milliseconds */
+	ASK_INTERVAL = 1000,
+	LOOK_TIMEOUT = 20000,
+	/* the host's answers: this many at once, and one more each this often */
+	MAXIMUM_ANSWERS = 8,
+	ANSWER_INTERVAL = 250,
+};
+
+enum
+{
+	_code_message_ask = 'Q',
+	_code_message_invite = 'I',
+};
+
+/* Crockford's base 32: no I, L, O or U */
+static const char code_alphabet[] = "0123456789ABCDEFGHJKMNPQRSTVWXYZ";
+
+static struct
+{
+	/* hosting: the code, its topic and key, and the invite it stands for */
+	int hosting;
+	char host_code[CODE_SYMBOLS + 1];
+	char host_topic[P2P_CODE_TOPIC_SIZE];
+	unsigned char host_key[P2P_SHA256_SIZE];
+	unsigned char invite[CODE_INVITE_SIZE];
+	int answers_left;
+	unsigned long answers_time;
+
+	/* looking a code up */
+	int status;
+	char look_topic[P2P_CODE_TOPIC_SIZE];
+	unsigned char look_key[P2P_SHA256_SIZE];
+	unsigned char look_nonce[CODE_NONCE_SIZE];
+	unsigned long look_started_time;
+	unsigned long asked_time;
+	int asked;
+} code;
+
+static int code_elapsed(unsigned long since, unsigned long time)
+{
+	return (unsigned int)(p2p_now() - since) >= (unsigned int)time;
+}
+
+/* the code's symbols from what was typed: letters and digits, read as
+Crockford reads them (O as 0, I and L as 1), the rest (dashes, spaces)
+left out; 0 unless they are exactly a code's */
+static int code_normalize(const char *text, char *symbols)
+{
+	int count = 0;
+
+	for (; *text; text++)
+	{
+		char character = *text;
+
+		if (character >= 'a' && character <= 'z')
+			character = (char)(character - 'a' + 'A');
+		if (character == 'O')
+			character = '0';
+		else if (character == 'I' || character == 'L')
+			character = '1';
+		if (!strchr(code_alphabet, character) || !character)
+		{
+			if (character == '-' || character == ' ' || character == '\t' || character == '\r' ||
+				character == '\n')
+			{
+				continue;
+			}
+			return 0;
+		}
+		if (count == CODE_SYMBOLS)
+			return 0;
+		symbols[count++] = character;
+	}
+	symbols[count] = 0;
+	return count == CODE_SYMBOLS;
+}
+
+/* the topic and key of a code (PBKDF2-HMAC-SHA256, one block) */
+static void code_derive(const char *symbols, char *topic, unsigned char *key)
+{
+	static const char salt[] = "halo-ce-vr join code 1";
+	unsigned char block[sizeof(salt) - 1 + 4];
+	unsigned char u[P2P_SHA256_SIZE];
+	unsigned char derived[P2P_SHA256_SIZE];
+	unsigned char digest[P2P_SHA256_SIZE];
+	char hex[2 * P2P_SHA256_SIZE + 1];
+	int iteration;
+	int index;
+
+	memcpy(block, salt, sizeof(salt) - 1);
+	block[sizeof(salt) - 1] = 0;
+	block[sizeof(salt)] = 0;
+	block[sizeof(salt) + 1] = 0;
+	block[sizeof(salt) + 2] = 1;
+	p2p_hmac_sha256((const unsigned char *)symbols, CODE_SYMBOLS, block, sizeof(block), u);
+	memcpy(derived, u, sizeof(derived));
+	for (iteration = 1; iteration < CODE_KDF_ITERATIONS; iteration++)
+	{
+		p2p_hmac_sha256((const unsigned char *)symbols, CODE_SYMBOLS, u, sizeof(u), u);
+		for (index = 0; index < P2P_SHA256_SIZE; index++)
+			derived[index] ^= u[index];
+	}
+	p2p_hmac_sha256(derived, sizeof(derived), "topic", 5, digest);
+	p2p_hex(digest, 16, hex);
+	snprintf(topic, P2P_CODE_TOPIC_SIZE, "hcvr/1/%s", hex);
+	p2p_hmac_sha256(derived, sizeof(derived), "seal", 4, key);
+}
+
+/* ---------- p2p.c's side (under p2p_lock) */
+
+void p2p_code_host(const unsigned char *invite)
+{
+	unsigned char random[CODE_SYMBOLS];
+	int index;
+
+	posix_random_bytes(random, sizeof(random));
+	for (index = 0; index < CODE_SYMBOLS; index++)
+		code.host_code[index] = code_alphabet[random[index] & 31];
+	code.host_code[CODE_SYMBOLS] = 0;
+	memcpy(code.invite, invite, CODE_INVITE_SIZE);
+	code_derive(code.host_code, code.host_topic, code.host_key);
+	code.answers_left = MAXIMUM_ANSWERS;
+	code.answers_time = p2p_now();
+	code.hosting = 1;
+	platform_log("Internet play: join code %.4s-%.4s", code.host_code, code.host_code + 4);
+	p2p_signal_sync_topics();
+}
+
+void p2p_code_stop_hosting(void)
+{
+	code.hosting = 0;
+	code.host_code[0] = 0;
+	p2p_signal_sync_topics();
+}
+
+int p2p_code_hosted(char *text, int size)
+{
+	if (!code.hosting || size < CODE_SYMBOLS + 2)
+		return 0;
+	snprintf(text, (size_t)size, "%.4s-%.4s", code.host_code, code.host_code + 4);
+	return 1;
+}
+
+int p2p_code_look_up(const char *typed)
+{
+	char symbols[CODE_SYMBOLS + 1];
+
+	if (!code_normalize(typed, symbols))
+	{
+		code.status = P2P_CODE_INVALID;
+		return 0;
+	}
+	if (code.hosting && !strcmp(symbols, code.host_code))
+	{
+		code.status = P2P_CODE_OWN;
+		return 0;
+	}
+	code_derive(symbols, code.look_topic, code.look_key);
+	posix_random_bytes(code.look_nonce, sizeof(code.look_nonce));
+	code.look_started_time = p2p_now();
+	code.asked = 0;
+	code.status = P2P_CODE_LOOKING;
+	p2p_signal_sync_topics();
+	return 1;
+}
+
+int p2p_code_status(void)
+{
+	return code.status;
+}
+
+void p2p_code_clear_status(void)
+{
+	if (code.status != P2P_CODE_LOOKING)
+		code.status = P2P_CODE_IDLE;
+}
+
+/* ---------- p2p_signal.c's side (under p2p_lock) */
+
+void p2p_code_topics(const char **host_topic, const char **look_topic)
+{
+	*host_topic = code.hosting ? code.host_topic : "";
+	*look_topic = code.status == P2P_CODE_LOOKING ? code.look_topic : "";
+}
+
+static void code_answer(const unsigned char *nonce)
+{
+	unsigned char message[2 + CODE_NONCE_SIZE + CODE_INVITE_SIZE];
+	unsigned char sealed[2 + sizeof(message) + P2P_SEAL_OVERHEAD];
+	int sealed_size;
+
+	/* (anyone watching the brokers can ask, as often as they like) */
+	while (code.answers_left < MAXIMUM_ANSWERS && code_elapsed(code.answers_time, ANSWER_INTERVAL))
+	{
+		code.answers_left++;
+		code.answers_time += ANSWER_INTERVAL;
+	}
+	if (code.answers_left == MAXIMUM_ANSWERS)
+		code.answers_time = p2p_now();
+	if (code.answers_left <= 0)
+		return;
+	code.answers_left--;
+	message[0] = _code_message_invite;
+	message[1] = CODE_MESSAGE_VERSION;
+	memcpy(message + 2, nonce, CODE_NONCE_SIZE);
+	memcpy(message + 2 + CODE_NONCE_SIZE, code.invite, CODE_INVITE_SIZE);
+	sealed[0] = _code_message_invite;
+	sealed[1] = CODE_MESSAGE_VERSION;
+	sealed_size = p2p_seal(code.host_key, message, sizeof(message), sealed + 2);
+	p2p_signal_publish(code.host_topic, sealed, 2 + sealed_size);
+}
+
+static void code_invite_received(const unsigned char *payload, int size)
+{
+	unsigned char message[2 + CODE_NONCE_SIZE + CODE_INVITE_SIZE + 16];
+	int message_size;
+	char hex[2 * CODE_INVITE_SIZE + 1];
+	char link[P2P_LINK_SIZE];
+
+	if (size > (int)sizeof(message) + P2P_SEAL_OVERHEAD)
+		return;
+	message_size = p2p_open(code.look_key, payload, size, message);
+	if (message_size != 2 + CODE_NONCE_SIZE + CODE_INVITE_SIZE || message[0] != _code_message_invite ||
+		message[1] != CODE_MESSAGE_VERSION || !p2p_equal(message + 2, code.look_nonce, CODE_NONCE_SIZE))
+	{
+		return;
+	}
+	code.status = P2P_CODE_FOUND;
+	p2p_signal_sync_topics();
+	p2p_hex(message + 2 + CODE_NONCE_SIZE, CODE_INVITE_SIZE, hex);
+	snprintf(link, sizeof(link), "halo://join/%s", hex);
+	platform_log("Internet play: the join code's host answered");
+	p2p_invite_received(link);
+}
+
+int p2p_code_received(const char *topic, const unsigned char *payload, int size)
+{
+	if (size < 2 || payload[1] != CODE_MESSAGE_VERSION)
+		return 0;
+	if (code.hosting && !strcmp(topic, code.host_topic))
+	{
+		if (payload[0] == _code_message_ask && size == 2 + CODE_NONCE_SIZE)
+			code_answer(payload + 2);
+		return 1;
+	}
+	if (code.status == P2P_CODE_LOOKING && !strcmp(topic, code.look_topic))
+	{
+		if (payload[0] == _code_message_invite)
+			code_invite_received(payload + 2, size - 2);
+		return 1;
+	}
+	return 0;
+}
+
+void p2p_code_update(void)
+{
+	unsigned char message[2 + CODE_NONCE_SIZE];
+
+	if (code.status != P2P_CODE_LOOKING)
+		return;
+	p2p_signal_start();
+	if (code_elapsed(code.look_started_time, LOOK_TIMEOUT))
+	{
+		code.status = P2P_CODE_NOT_FOUND;
+		p2p_signal_sync_topics();
+		platform_log("Internet play: no game answered the join code");
+		return;
+	}
+	if (!p2p_signal_connected() || (code.asked && !code_elapsed(code.asked_time, ASK_INTERVAL)))
+		return;
+	message[0] = _code_message_ask;
+	message[1] = CODE_MESSAGE_VERSION;
+	memcpy(message + 2, code.look_nonce, CODE_NONCE_SIZE);
+	p2p_signal_publish(code.look_topic, message, sizeof(message));
+	code.asked = 1;
+	code.asked_time = p2p_now();
+}

port/linux/src/p2p_internal.h

@@ -107,6 +107,52 @@ void p2p_signal_join(const unsigned char *host_hash, const unsigned char *token)
 void p2p_signal_stop_joining(void);
 /* whether any broker is connected */
 int p2p_signal_connected(void);
+/* (for p2p_code.c) the topics every broker listens on, as they are now; and
+a message to a topic through every broker */
+void p2p_signal_sync_topics(void);
+void p2p_signal_publish(const char *topic, const unsigned char *payload, int size);
+/* the same, kept by the brokers for whoever listens later (empty: no
+longer) */
+void p2p_signal_publish_retained(const char *topic, const unsigned char *payload, int size);
+
+/* ---------- p2p_code.c: join codes (under p2p_lock) */
+
+enum
+{
+	P2P_CODE_TOPIC_SIZE = 7 + 32 + 1,
+};
+
+/* hosting: a new code for the invite (its key hash and token), and none */
+void p2p_code_host(const unsigned char *invite);
+void p2p_code_stop_hosting(void);
+/* the code hosted, as XXXX-XXXX; 0 if none */
+int p2p_code_hosted(char *text, int size);
+/* starts looking up a typed code (0: not a code, or this machine's own;
+p2p_code_status says which) */
+int p2p_code_look_up(const char *typed);
+int p2p_code_status(void);
+/* forgets a finished look up's result */
+void p2p_code_clear_status(void);
+/* (p2p_signal.c) the topics to listen on (empty: none); a message on a
+topic, nonzero if it was a code's; and each pass of the p2p thread */
+void p2p_code_topics(const char **host_topic, const char **look_topic);
+int p2p_code_received(const char *topic, const unsigned char *payload, int size);
+void p2p_code_update(void);
+
+/* ---------- p2p_list.c: public games (under p2p_lock) */
+
+/* hosting: whether the game is listed, and what it is */
+void p2p_list_set_public(int public_game);
+int p2p_list_public(void);
+void p2p_list_set_description(const char *name, const char *map, const char *mode, int players,
+	int maximum_players);
+/* the games listed lately; asking keeps this machine listening a while */
+int p2p_list_games(struct p2p_public_game *games, int maximum);
+/* (p2p_signal.c) the topic to listen on (empty: none); a message on one
+(nonzero if it was a listing's); and each pass, whether hosting */
+const char *p2p_list_topic(void);
+int p2p_list_received(const char *topic, const unsigned char *payload, int size);
+void p2p_list_update(int hosting);
 
 /* ---------- p2p_crypto.c */
 

port/linux/src/p2p_list.c

@@ -0,0 +1,335 @@
+/*
+P2P_LIST.C
+
+Public games (the VR port's): a host may list its game for anyone, who
+finds it in a list of online games and joins it by its join code
+(p2p_code.c), without a server of this project's.
+
+- A public game's host announces it through the signalling brokers
+  (p2p_signal.c) every ANNOUNCE_INTERVAL, retained, on a topic of its own
+  under hcvr/1/g<network version>/: its name, map, game type, players, its
+  join code, and the time. Retained, a machine that starts listening gets
+  every game's latest at once. A host that stops (it closes its game, or
+  makes it private) clears its topic; one that quits without that leaves
+  its last announcement, which listeners drop once it is older than
+  STALE_SECONDS (by the machines' clocks).
+- A machine that shows the list listens on the topics of its network
+  version (a wildcard), and keeps the games heard of lately.
+- An announcement carries no address: a machine reaches a public game's
+  host only by its code, as anyone given the code does. Anyone can announce
+  anything, so what is shown is checked to be printable and in bounds, and
+  a game that is not what it says is only a code that does not answer.
+*/
+
+#include "platform.h"
+#include "posix.h"
+#include "port_config.h"
+#include "p2p_internal.h"
+#include "halo_port_limits.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+
+enum
+{
+	ANNOUNCEMENT_VERSION = 1,
+	/* milliseconds */
+	ANNOUNCE_INTERVAL = 10000,
+	/* a listener's interest lapses this long after the menu last asked */
+	WATCH_TIME = 3000,
+	STALE_SECONDS = 45,
+	MAXIMUM_LISTED_GAMES = 32,
+};
+
+/* what goes to the brokers (byte for byte) */
+struct announcement
+{
+	char magic[4];
+	unsigned char version;
+	unsigned char players;
+	unsigned char maximum_players;
+	unsigned char flags;
+	unsigned char time[8];
+	char code[8];
+	char name[P2P_PUBLIC_NAME_SIZE];
+	char map[P2P_PUBLIC_MAP_SIZE];
+	char mode[P2P_PUBLIC_MODE_SIZE];
+};
+
+struct listed_game
+{
+	int used;
+	char topic[P2P_CODE_TOPIC_SIZE];
+	unsigned long heard_time;
+	long long announced_time;
+	struct p2p_public_game game;
+};
+
+static struct
+{
+	/* hosting (whether public: network.public_game, until Y changes it) */
+	int initialized;
+	int public_game;
+	char topic[P2P_CODE_TOPIC_SIZE];
+	int announced;
+	unsigned long announced_time;
+	char name[P2P_PUBLIC_NAME_SIZE];
+	char map[P2P_PUBLIC_MAP_SIZE];
+	char mode[P2P_PUBLIC_MODE_SIZE];
+	int players;
+	int maximum_players;
+
+	/* listening */
+	unsigned long watched_time;
+	int watching;
+	char watch_topic[P2P_CODE_TOPIC_SIZE];
+	struct listed_game games[MAXIMUM_LISTED_GAMES];
+} list;
+
+static int list_elapsed(unsigned long since, unsigned long time)
+{
+	return (unsigned int)(p2p_now() - since) >= (unsigned int)time;
+}
+
+/* text as shown: printable ASCII only, ended */
+static void list_text(char *destination, int size, const char *source, int source_size)
+{
+	int index;
+
+	for (index = 0; index < size - 1 && index < source_size && source[index]; index++)
+		destination[index] = source[index] >= 32 && source[index] < 127 ? source[index] : '?';
+	destination[index] = 0;
+}
+
+static long long list_time_now(void)
+{
+	return (long long)time(NULL);
+}
+
+static void list_topics_make(void)
+{
+	if (!list.topic[0])
+	{
+		unsigned char random[8];
+		char hex[17];
+
+		posix_random_bytes(random, sizeof(random));
+		p2p_hex(random, sizeof(random), hex);
+		snprintf(list.topic, sizeof(list.topic), "hcvr/1/g%d/%s", HALO_PORT_NETWORK_VERSION, hex);
+	}
+	if (!list.watch_topic[0])
+		snprintf(list.watch_topic, sizeof(list.watch_topic), "hcvr/1/g%d/+", HALO_PORT_NETWORK_VERSION);
+}
+
+static void list_announce(void)
+{
+	struct announcement announcement;
+	char code[16];
+	long long now = list_time_now();
+	int index;
+
+	if (!p2p_code_hosted(code, sizeof(code)))
+		return;
+	memset(&announcement, 0, sizeof(announcement));
+	memcpy(announcement.magic, "HCVR", 4);
+	announcement.version = ANNOUNCEMENT_VERSION;
+	announcement.players = (unsigned char)(list.players < 0 ? 0 : list.players > 255 ? 255 : list.players);
+	announcement.maximum_players =
+		(unsigned char)(list.maximum_players < 0 ? 0 : list.maximum_players > 255 ? 255 : list.maximum_players);
+	for (index = 0; index < 8; index++)
+		announcement.time[index] = (unsigned char)(now >> (8 * index));
+	/* (the code without its dash) */
+	memcpy(announcement.code, code, 4);
+	memcpy(announcement.code + 4, code + 5, 4);
+	memcpy(announcement.name, list.name, sizeof(announcement.name));
+	memcpy(announcement.map, list.map, sizeof(announcement.map));
+	memcpy(announcement.mode, list.mode, sizeof(announcement.mode));
+	p2p_signal_publish_retained(list.topic, (const unsigned char *)&announcement, sizeof(announcement));
+	if (!list.announced)
+		platform_log("Internet play: the game is listed as public (%s, %s, %s)", list.name, list.map, list.mode);
+	list.announced = 1;
+	list.announced_time = p2p_now();
+}
+
+static void list_withdraw(void)
+{
+	if (!list.announced)
+		return;
+	p2p_signal_publish_retained(list.topic, NULL, 0);
+	platform_log("Internet play: the game is no longer listed as public");
+	list.announced = 0;
+}
+
+/* ---------- p2p.c's side (under p2p_lock) */
+
+void p2p_list_set_public(int public_game)
+{
+	if (public_game == list.public_game)
+		return;
+	list.public_game = public_game;
+	list_topics_make();
+	if (!public_game)
+		list_withdraw();
+	else
+		list.announced_time = p2p_now() - ANNOUNCE_INTERVAL;
+}
+
+int p2p_list_public(void)
+{
+	return list.public_game;
+}
+
+void p2p_list_set_description(const char *name, const char *map, const char *mode, int players,
+	int maximum_players)
+{
+	int changed = strncmp(list.name, name, sizeof(list.name) - 1) || strncmp(list.map, map, sizeof(list.map) - 1) ||
+		strncmp(list.mode, mode, sizeof(list.mode) - 1) || players != list.players ||
+		maximum_players != list.maximum_players;
+
+	list_text(list.name, sizeof(list.name), name, P2P_PUBLIC_NAME_SIZE);
+	list_text(list.map, sizeof(list.map), map, P2P_PUBLIC_MAP_SIZE);
+	list_text(list.mode, sizeof(list.mode), mode, P2P_PUBLIC_MODE_SIZE);
+	list.players = players;
+	list.maximum_players = maximum_players;
+	/* (a change goes out soon, not at the next interval) */
+	if (changed && list.announced && list_elapsed(list.announced_time, 1000))
+		list.announced_time = p2p_now() - ANNOUNCE_INTERVAL;
+}
+
+int p2p_list_games(struct p2p_public_game *games, int maximum)
+{
+	int count = 0;
+	int index;
+
+	list.watched_time = p2p_now();
+	list.watching = 1;
+	for (index = 0; index < MAXIMUM_LISTED_GAMES && count < maximum; index++)
+	{
+		if (list.games[index].used)
+			games[count++] = list.games[index].game;
+	}
+	return count;
+}
+
+/* ---------- p2p_signal.c's side (under p2p_lock) */
+
+const char *p2p_list_topic(void)
+{
+	return list.watching ? list.watch_topic : "";
+}
+
+int p2p_list_received(const char *topic, const unsigned char *payload, int size)
+{
+	struct announcement announcement;
+	struct listed_game *slot = NULL;
+	long long announced = 0;
+	char code[16];
+	int index;
+
+	if (!list.watch_topic[0] || strncmp(topic, list.watch_topic, strlen(list.watch_topic) - 1))
+		return 0;
+	/* (this machine's own, as the broker echoes it) */
+	if (!strcmp(topic, list.topic))
+		return 1;
+	for (index = 0; index < MAXIMUM_LISTED_GAMES; index++)
+	{
+		if (list.games[index].used && !strcmp(list.games[index].topic, topic))
+			slot = &list.games[index];
+	}
+	if (size != (int)sizeof(announcement))
+	{
+		/* (empty: withdrawn) */
+		if (slot && size == 0)
+			slot->used = 0;
+		return 1;
+	}
+	memcpy(&announcement, payload, sizeof(announcement));
+	if (memcmp(announcement.magic, "HCVR", 4) || announcement.version != ANNOUNCEMENT_VERSION ||
+		!announcement.maximum_players || announcement.players > announcement.maximum_players)
+	{
+		return 1;
+	}
+	for (index = 0; index < 8; index++)
+		announced |= (long long)announcement.time[index] << (8 * index);
+	if (announced < list_time_now() - STALE_SECONDS || announced > list_time_now() + STALE_SECONDS)
+	{
+		if (slot)
+			slot->used = 0;
+		return 1;
+	}
+	snprintf(code, sizeof(code), "%.4s-%.4s", announcement.code, announcement.code + 4);
+	for (index = 0; code[index]; index++)
+	{
+		if (index != 4 && !((code[index] >= '0' && code[index] <= '9') || (code[index] >= 'A' && code[index] <= 'Z')))
+			return 1;
+	}
+	if (!slot)
+	{
+		int oldest = -1;
+
+		for (index = 0; index < MAXIMUM_LISTED_GAMES && !slot; index++)
+		{
+			if (!list.games[index].used)
+				slot = &list.games[index];
+			else if (oldest < 0 || list.games[index].announced_time < list.games[oldest].announced_time)
+				oldest = index;
+		}
+		if (!slot)
+			slot = &list.games[oldest];
+		memset(slot, 0, sizeof(*slot));
+		snprintf(slot->topic, sizeof(slot->topic), "%s", topic);
+	}
+	slot->used = 1;
+	slot->heard_time = p2p_now();
+	slot->announced_time = announced;
+	list_text(slot->game.name, sizeof(slot->game.name), announcement.name, sizeof(announcement.name));
+	list_text(slot->game.map, sizeof(slot->game.map), announcement.map, sizeof(announcement.map));
+	list_text(slot->game.mode, sizeof(slot->game.mode), announcement.mode, sizeof(announcement.mode));
+	snprintf(slot->game.code, sizeof(slot->game.code), "%s", code);
+	slot->game.players = announcement.players;
+	slot->game.maximum_players = announcement.maximum_players;
+	return 1;
+}
+
+void p2p_list_update(int hosting)
+{
+	int index;
+
+	if (!list.initialized)
+	{
+		list.initialized = 1;
+		if (!list.public_game)
+			list.public_game = config_boolean("network.public_game");
+	}
+	list_topics_make();
+	/* hosting a public game: announced every so often; withdrawn when it
+	is not */
+	if (hosting && list.public_game)
+	{
+		p2p_signal_start();
+		if (p2p_signal_connected() && list_elapsed(list.announced_time, ANNOUNCE_INTERVAL))
+			list_announce();
+	}
+	else if (list.announced)
+	{
+		list_withdraw();
+	}
+	/* listening while the menu asks */
+	if (list.watching && list_elapsed(list.watched_time, WATCH_TIME))
+	{
+		list.watching = 0;
+		memset(list.games, 0, sizeof(list.games));
+		p2p_signal_sync_topics();
+	}
+	else if (list.watching)
+	{
+		p2p_signal_start();
+		p2p_signal_sync_topics();
+	}
+	for (index = 0; index < MAXIMUM_LISTED_GAMES; index++)
+	{
+		if (list.games[index].used && list.games[index].announced_time < list_time_now() - STALE_SECONDS)
+			list.games[index].used = 0;
+	}
+}

port/linux/src/p2p_signal.c

@@ -82,6 +82,8 @@ enum
 	one is not forgotten while its host nonce lasts: USED_REQUEST_TIME) */
 	MAXIMUM_USED_REQUESTS = 1024,
 	TOPIC_SIZE = 7 + 32 + 1,
+	/* (p2p_code.c's are as long) */
+	TOPIC_SIZE_CHECK = 1 / (TOPIC_SIZE == P2P_CODE_TOPIC_SIZE),
 	NONCE_SIZE = 8,
 	/* an ACCEPT's or a proven JOIN's tag: the first half of an HMAC-SHA256 */
 	TAG_SIZE = 16,
@@ -152,6 +154,11 @@ struct broker
 	/* the topics it has been asked for */
 	char host_topic[TOPIC_SIZE];
 	char join_topic[TOPIC_SIZE];
+	/* (join codes' topics: p2p_code.c) */
+	char code_host_topic[TOPIC_SIZE];
+	char code_look_topic[TOPIC_SIZE];
+	/* (public games': p2p_list.c) */
+	char list_topic[TOPIC_SIZE];
 	unsigned char input[BUFFER_SIZE];
 	int input_size;
 	unsigned char output[BUFFER_SIZE];
@@ -321,6 +328,9 @@ static void broker_close(struct broker *broker, int failed)
 	broker->output_size = 0;
 	broker->host_topic[0] = 0;
 	broker->join_topic[0] = 0;
+	broker->code_host_topic[0] = 0;
+	broker->code_look_topic[0] = 0;
+	broker->list_topic[0] = 0;
 	if (failed)
 		broker->failures++;
 }
@@ -410,17 +420,22 @@ static void broker_publish(struct broker *broker, const char *topic, const unsig
 /* the topics a ready broker should be subscribed to */
 static void broker_sync_topics(struct broker *broker)
 {
-	const char *wanted[2];
-	char *had[2];
+	const char *wanted[5];
+	char *had[5];
 	int index;
 
 	if (broker->state != _broker_ready)
 		return;
 	wanted[0] = signalling.hosting ? signalling.host_topic : "";
 	wanted[1] = signalling.joining ? signalling.join_topic : "";
+	p2p_code_topics(&wanted[2], &wanted[3]);
+	wanted[4] = p2p_list_topic();
 	had[0] = broker->host_topic;
 	had[1] = broker->join_topic;
-	for (index = 0; index < 2; index++)
+	had[2] = broker->code_host_topic;
+	had[3] = broker->code_look_topic;
+	had[4] = broker->list_topic;
+	for (index = 0; index < 5; index++)
 	{
 		if (!strcmp(wanted[index], had[index]))
 			continue;
@@ -939,6 +954,8 @@ static void publish_received(struct broker *broker, const char *topic, const uns
 
 	if (size > MAXIMUM_MESSAGE_SIZE + P2P_SEAL_OVERHEAD)
 		return;
+	if (p2p_code_received(topic, payload, size) || p2p_list_received(topic, payload, size))
+		return;
 	if (signalling.hosting && !strcmp(topic, signalling.host_topic))
 	{
 		message_size = p2p_open(signalling.host_key, payload, size, message);
@@ -1190,6 +1207,8 @@ void p2p_signal_update(const int *read, int read_count, const int *write, int wr
 	}
 	if (signalling.joining && elapsed(signalling.join_sent_time, JOIN_INTERVAL))
 		send_join();
+	p2p_code_update();
+	p2p_list_update(signalling.hosting);
 }
 
 int p2p_signal_connected(void)
@@ -1212,6 +1231,39 @@ static void sync_all_topics(void)
 		broker_sync_topics(&signalling.brokers[index]);
 }
 
+void p2p_signal_sync_topics(void)
+{
+	sync_all_topics();
+}
+
+void p2p_signal_publish(const char *topic, const unsigned char *payload, int size)
+{
+	if (size <= MAXIMUM_MESSAGE_SIZE + P2P_SEAL_OVERHEAD)
+		publish_everywhere(topic, payload, size);
+}
+
+void p2p_signal_publish_retained(const char *topic, const unsigned char *payload, int size)
+{
+	unsigned char body[2 + TOPIC_SIZE + MAXIMUM_MESSAGE_SIZE];
+	int index;
+
+	if (size > MAXIMUM_MESSAGE_SIZE)
+		return;
+	for (index = 0; index < signalling.broker_count; index++)
+	{
+		struct broker *broker = &signalling.brokers[index];
+		int body_size;
+
+		if (broker->state != _broker_ready)
+			continue;
+		body_size = put_string(body, topic);
+		if (size)
+			memcpy(body + body_size, payload, (size_t)size);
+		/* (PUBLISH, at most once, retained: an empty one clears it) */
+		broker_send(broker, 0x31, body, body_size + size);
+	}
+}
+
 void p2p_signal_host(const unsigned char *token)
 {
 	if (!signalling.has_nonce_key)

port/linux/src/port_config.c

@@ -275,6 +275,9 @@ static const struct config_setting config_settings[] =
 		"clipboard) that lets whoever has it join over the internet; opening a\n"
 		"link (or copying one before switching to the game) joins. Only people\n"
 		"with the invite can join. Off keeps system link to the local network." },
+	{ "network.public_game", _config_boolean, "false", "HALO_NET_PUBLIC_GAME", _environment_value, _platform_all,
+		"Host games as public: listed for anyone among the online games (the\n"
+		"system link screen's X), as Y in a hosted game's lobby makes them." },
 	{ "network.join_from_clipboard", _config_boolean, "true", "HALO_NET_JOIN_FROM_CLIPBOARD", _environment_value,
 		_platform_all,
 		"Join the game of an invite link found on the clipboard when the game\n"
@@ -301,6 +304,17 @@ static const struct config_setting config_settings[] =
 		"The Discord application internet play invites go through while the\n"
 		"Discord desktop client runs; empty for none." },
 
+	{ "voice.enabled", _config_boolean, "true", "HALO_VOICE_ENABLED", _environment_value, _platform_android,
+		"Voice chat in multiplayer: hear the other players (teammates over the\n"
+		"radio, the rest when near, from where they are)." },
+	{ "voice.microphone", _config_boolean, "true", "HALO_VOICE_MICROPHONE", _environment_value, _platform_android,
+		"Send your voice in multiplayer, whenever you speak (the headset's\n"
+		"microphone; Android asks for it once). False only listens." },
+	{ "voice.volume", _config_real, "1.0", "HALO_VOICE_VOLUME", _environment_value, _platform_android,
+		"The other players' voices' volume (1 as they come)." },
+	{ "voice.threshold", _config_real, "0.02", "HALO_VOICE_THRESHOLD", _environment_value, _platform_android,
+		"How loud the microphone must be to send (0..1 of full scale): higher\n"
+		"if it sends noise, lower if it cuts words off." },
 	{ "update.auto", _config_boolean, "true", "HALO_UPDATE_AUTO", _environment_value, _platform_all,
 		"Look for a new version when the game starts, and offer to update to it;\n"
 		"false never looks (the game's \"Do not ask again\" writes false here)." },

port/linux/src/sdl_platform.c

@@ -614,18 +614,56 @@ static BOOL platform_text_has_invite_link(const char *text)
 	return FALSE;
 }
 
+/* the last clipboard text looked at, kept beside the settings from run to
+run (the VR port's): a run's own invite, still on the clipboard when the
+game starts again, is not joined then (its host, the run before, is gone,
+and the attempt held up a join for a minute and a half) */
+static void platform_clipboard_seen(char *seen, int size, BOOL save)
+{
+	char path[512];
+	FILE *file;
+
+	snprintf(path, sizeof(path), "%s/clipboard_seen.txt", platform_data_root());
+	if (save)
+	{
+		file = fopen(path, "wb");
+		if (file)
+		{
+			fputs(seen, file);
+			fclose(file);
+		}
+		return;
+	}
+	file = fopen(path, "rb");
+	if (!file)
+		return;
+	{
+		size_t length = fread(seen, 1, (size_t)size - 1, file);
+
+		seen[length] = 0;
+	}
+	fclose(file);
+}
+
 /* puts a new invite on the clipboard, and joins one found there when the
 game comes to the front */
 static void platform_invite_clipboard(BOOL look)
 {
 	/* the last clipboard text looked at, so each invite is joined once */
 	static char seen[256];
+	static BOOL seen_loaded;
 	const char *invite = p2p_take_clipboard_text();
 
+	if (!seen_loaded)
+	{
+		seen_loaded = TRUE;
+		platform_clipboard_seen(seen, sizeof(seen), FALSE);
+	}
 	if (invite)
 	{
 		SDL_SetClipboardText(invite);
 		snprintf(seen, sizeof(seen), "%s", invite);
+		platform_clipboard_seen(seen, sizeof(seen), TRUE);
 		platform_log("Internet play: the invite link is on the clipboard");
 #ifdef HALO_ANDROID
 		SDL_ShowAndroidToast("Hosting: the invite link is on the clipboard", 1, -1, 0, 0);
@@ -638,6 +676,7 @@ static void platform_invite_clipboard(BOOL look)
 		if (text && strcmp(text, seen) && strlen(text) < sizeof(seen))
 		{
 			snprintf(seen, sizeof(seen), "%s", text);
+			platform_clipboard_seen(seen, sizeof(seen), TRUE);
 			/* (a link, not a bare code: 64 hex digits alone are as often a
 			checksum copied for something else) */
 			if (platform_text_has_invite_link(text) && p2p_join_invite(text))

port/linux/src/voice.c

@@ -0,0 +1,87 @@
+/*
+VOICE.C
+
+The voice chat's sound (halo_voice.h): on Android, the host's
+(port/android/host/host_voice.c); elsewhere none.
+*/
+
+#include "halo_voice.h"
+#include "platform.h"
+#include "port_config.h"
+
+#ifdef HALO_ANDROID
+#include "guest_host.h"
+
+#include <stdio.h>
+
+static int voice_started;
+
+/* whether the app may use the microphone, as the launcher found
+(LauncherActivity.java): opened without it, Android would ask in the middle
+of the game */
+static int voice_microphone_allowed(void)
+{
+	char path[512];
+	FILE *file;
+	int allowed = 0;
+
+	snprintf(path, sizeof(path), "%s/microphone_permission.txt", platform_data_root());
+	file = fopen(path, "rb");
+	if (file)
+	{
+		allowed = fgetc(file) == '1';
+		fclose(file);
+	}
+	return allowed;
+}
+
+int halo_voice_enabled(void)
+{
+	return config_boolean("voice.enabled");
+}
+
+int halo_voice_begin(void)
+{
+	int microphone;
+
+	if (voice_started)
+		return 1;
+	voice_started = 1;
+	microphone = config_boolean("voice.microphone") && voice_microphone_allowed();
+	platform_log("voice: on, %s", microphone ? "with the microphone" :
+		config_boolean("voice.microphone") ? "without the microphone (not allowed)" : "listening only");
+	return host_voice_start(microphone, (float)config_real("voice.volume"), (float)config_real("voice.threshold"));
+}
+
+void halo_voice_end(void)
+{
+	if (!voice_started)
+		return;
+	voice_started = 0;
+	host_voice_stop();
+	platform_log("voice: off");
+}
+
+int halo_voice_take(void *buffer, int size)
+{
+	return voice_started ? host_voice_take_packets(buffer, size) : 0;
+}
+
+void halo_voice_play(int speaker, int sequence, const void *data, int length, float left, float right)
+{
+	if (voice_started)
+		host_voice_play(speaker, sequence, data, length, left, right);
+}
+
+#else
+
+int halo_voice_enabled(void) { return 0; }
+int halo_voice_begin(void) { return 0; }
+void halo_voice_end(void) {}
+int halo_voice_take(void *buffer, int size) { (void)buffer; (void)size; return 0; }
+void halo_voice_play(int speaker, int sequence, const void *data, int length, float left, float right)
+{
+	(void)speaker; (void)sequence; (void)data; (void)length; (void)left; (void)right;
+}
+
+#endif

source/interface/event_manager.c

@@ -42,7 +42,13 @@ enum
 	_event_type_right_stick,
 	_event_type_button,
 
+#ifdef HALO_ANDROID
+	/* (the VR port's: a headset's controllers' thumbsticks are pushed as
+	far less readily than a gamepad's) */
+	STICK_EVENT_THRESHOLD = 22937,
+#else
 	STICK_EVENT_THRESHOLD = 29490,
+#endif
 	STICK_EVENT_REPEAT_MILLISECONDS = 250
 };
 
@@ -71,6 +77,24 @@ typedef char verify_event_manager_state_size[
 typedef char verify_event_manager_globals_size[
 	sizeof(struct event_manager_globals) == 0x168 ? 1 : -1];
 
+#ifdef HALO_ANDROID
+/* The VR port's: a stick held moves on once after a pause, then quickly,
+as menus do now (the Xbox's moved on every quarter second, which in a
+headset, with the keyboard's letters to cross, is slow going). */
+enum
+{
+	STICK_REPEAT_FIRST_MILLISECONDS = 350,
+	STICK_REPEAT_MILLISECONDS = 90,
+};
+
+static short stick_repeats[NUMBER_OF_GAMEPAD_STICKS][MAXIMUM_GAMEPADS];
+
+#define STICK_REPEAT_INTERVAL(stick, controller_index) \
+	(stick_repeats[stick][controller_index] ? STICK_REPEAT_MILLISECONDS : STICK_REPEAT_FIRST_MILLISECONDS)
+#else
+#define STICK_REPEAT_INTERVAL(stick, controller_index) STICK_EVENT_REPEAT_MILLISECONDS
+#endif
+
 /* ---------- prototypes */
 
 static void queue_event(
@@ -83,6 +107,30 @@ struct event_manager_globals event_manager_globals = { 0 };
 
 /* ---------- public code */
 
+#ifdef HALO_ANDROID
+/* an event the stick posts: a fresh push (it was within the threshold on
+that axis) starts the count of repeats again */
+static void stick_note_event(
+	short stick,
+	short controller_index,
+	long x,
+	long y,
+	unsigned long time)
+{
+	boolean fresh =
+		(ABS(x) >= STICK_EVENT_THRESHOLD &&
+			ABS(event_manager_globals.previous_stick_axes[stick][0][controller_index]) < STICK_EVENT_THRESHOLD) ||
+		(ABS(y) >= STICK_EVENT_THRESHOLD &&
+			ABS(event_manager_globals.previous_stick_axes[stick][1][controller_index]) < STICK_EVENT_THRESHOLD);
+
+	(void)time;
+	if (fresh)
+		stick_repeats[stick][controller_index] = 0;
+	else if (stick_repeats[stick][controller_index] < SHORT_MAX)
+		stick_repeats[stick][controller_index]++;
+}
+
+#endif
 void event_manager_initialize(
 	void)
 {
@@ -209,12 +257,16 @@ static void queue_event(
 				ABS(event_manager_globals.previous_stick_axes[_gamepad_stick_left][0][controller_index]) < STICK_EVENT_THRESHOLD) ||
 			(ABS(y) >= STICK_EVENT_THRESHOLD &&
 				ABS(event_manager_globals.previous_stick_axes[_gamepad_stick_left][1][controller_index]) < STICK_EVENT_THRESHOLD) ||
-			time - event_manager_globals.stick_event_times[_gamepad_stick_left][controller_index] >= STICK_EVENT_REPEAT_MILLISECONDS))
+			time - event_manager_globals.stick_event_times[_gamepad_stick_left][controller_index] >=
+				STICK_REPEAT_INTERVAL(_gamepad_stick_left, controller_index)))
 		{
 			post = FALSE;
 		}
 		else
 		{
+#ifdef HALO_ANDROID
+			stick_note_event(_gamepad_stick_left, controller_index, x, y, time);
+#endif
 			event_manager_globals.stick_event_times[_gamepad_stick_left][controller_index] = time;
 			post = TRUE;
 
@@ -260,12 +312,16 @@ static void queue_event(
 				ABS(event_manager_globals.previous_stick_axes[_gamepad_stick_right][0][controller_index]) < STICK_EVENT_THRESHOLD) ||
 			(ABS(y) >= STICK_EVENT_THRESHOLD &&
 				ABS(event_manager_globals.previous_stick_axes[_gamepad_stick_right][1][controller_index]) < STICK_EVENT_THRESHOLD) ||
-			time - event_manager_globals.stick_event_times[_gamepad_stick_right][controller_index] >= STICK_EVENT_REPEAT_MILLISECONDS))
+			time - event_manager_globals.stick_event_times[_gamepad_stick_right][controller_index] >=
+				STICK_REPEAT_INTERVAL(_gamepad_stick_right, controller_index)))
 		{
 			post = FALSE;
 		}
 		else
 		{
+#ifdef HALO_ANDROID
+			stick_note_event(_gamepad_stick_right, controller_index, x, y, time);
+#endif
 			event_manager_globals.stick_event_times[_gamepad_stick_right][controller_index] = time;
 			post = TRUE;
 

source/interface/ui_widget.c

@@ -5591,6 +5591,429 @@ static boolean ui_mouse_menus_active(
 }
 
 #ifdef HALO_ANDROID
+/* ---------- join codes (the VR port's)
+
+Internet play's join codes (port/linux/src/p2p_code.c) and public games
+(p2p_list.c): the host's lobby shows its game's code, and Y there lists the
+game for anyone or not; on the screen of games to join, X opens a panel of
+the public games and a way to type a code in, either of which then joins as
+an invite link does (the game shows up in the list once its host is
+reached). */
+
+int p2p_join_code(char *text, int size);
+int p2p_join_with_code(char const *typed);
+int p2p_join_code_status(void);
+void p2p_join_code_clear_status(void);
+int p2p_join_state(void);
+
+enum
+{
+	/* p2p.h's */
+	_join_code_idle,
+	_join_code_looking,
+	_join_code_found,
+	_join_code_not_found,
+	_join_code_invalid,
+	_join_code_own,
+	_join_code_offline,
+};
+
+enum
+{
+	/* p2p.h's */
+	_join_state_none,
+	_join_state_reaching,
+	_join_state_connected,
+	_join_state_no_answer,
+	_join_state_blocked,
+	_join_state_lost,
+};
+
+struct ui_public_game
+{
+	/* p2p.h's struct p2p_public_game */
+	char name[16];
+	char map[32];
+	char mode[24];
+	char code[12];
+	int players;
+	int maximum_players;
+};
+
+void p2p_set_public_game(int public_game);
+int p2p_public_game(void);
+int p2p_public_games(struct ui_public_game *games, int maximum);
+int config_boolean(char const *name);
+int config_write_boolean(char const *name, int value);
+
+enum
+{
+	MAXIMUM_SHOWN_PUBLIC_GAMES = 32,
+	/* the online games panel's rows: "enter a code", the voice chat's
+	switches, and the games */
+	ONLINE_PANEL_ROWS = 11,
+	ONLINE_PANEL_FIXED_ROWS = 3,
+};
+
+static struct
+{
+	boolean keyboard_launched;
+	wchar_t typed[12];
+	/* the panel of online games, over the screen of games to join */
+	boolean panel_open;
+	short selection;
+	short scroll;
+	short game_count;
+	struct ui_public_game games[MAXIMUM_SHOWN_PUBLIC_GAMES];
+} ui_join_code_globals;
+
+/* the multiplayer maps' names, as the menus show them */
+static char const *ui_join_code_map_name(
+	char const *map)
+{
+	static char const *const names[][2] = {
+		{ "beavercreek", "Battle Creek" }, { "bloodgulch", "Blood Gulch" }, { "boardingaction", "Boarding Action" },
+		{ "carousel", "Derelict" }, { "chillout", "Chill Out" }, { "damnation", "Damnation" },
+		{ "dangercanyon", "Danger Canyon" }, { "deathisland", "Death Island" }, { "gephyrophobia", "Gephyrophobia" },
+		{ "hangemhigh", "Hang 'Em High" }, { "icefields", "Ice Fields" }, { "infinity", "Infinity" },
+		{ "longest", "Longest" }, { "prisoner", "Prisoner" }, { "putput", "Chiron TL-34" },
+		{ "ratrace", "Rat Race" }, { "sidewinder", "Sidewinder" }, { "timberland", "Timberland" },
+		{ "wizard", "Wizard" },
+	};
+	short index;
+
+	for (index = 0; index < (short)NUMBEROF(names); index++)
+	{
+		if (!strcmp(map, names[index][0]))
+			return names[index][1];
+	}
+	return map;
+}
+
+static boolean ui_join_code_screen_active(
+	char const *name)
+{
+	return widget_globals.active_widgets[0] && widget_globals.active_widgets[0]->name &&
+		strcmp(widget_globals.active_widgets[0]->name, name) == 0;
+}
+
+static void ui_join_code_launch_keyboard(
+	void)
+{
+	ui_join_code_globals.typed[0] = 0;
+	virtual_keyboard_set_caption(L"Enter the join code of an online game");
+	if (!virtual_keyboard_launch(ui_join_code_globals.typed, sizeof(ui_join_code_globals.typed), 8))
+	{
+		virtual_keyboard_set_caption(NULL);
+		return;
+	}
+	p2p_join_code_clear_status();
+	ui_join_code_globals.keyboard_launched = TRUE;
+}
+
+/* the panel's input: the stick or the pad's arrows choose a row, A takes
+it, B closes it */
+static void ui_join_code_panel_event(
+	struct event_record const *event)
+{
+	short rows = (short)(ui_join_code_globals.game_count + ONLINE_PANEL_FIXED_ROWS);
+	short move = 0;
+
+	if (event->type == _event_type_left_stick)
+	{
+		if (event->data.stick.y == SHORT_MAX)
+			move = -1;
+		else if (event->data.stick.y == SHORT_MIN)
+			move = 1;
+	}
+	else if (event->type == _event_type_button && event->data.button.value == 1)
+	{
+		switch (event->data.button.index)
+		{
+		case _gamepad_binary_button_dpad_up: move = -1; break;
+		case _gamepad_binary_button_dpad_down: move = 1; break;
+		case _gamepad_analog_button_b:
+		case _gamepad_binary_button_back:
+			ui_join_code_globals.panel_open = FALSE;
+			break;
+		case _gamepad_analog_button_x:
+			ui_join_code_globals.panel_open = FALSE;
+			ui_join_code_launch_keyboard();
+			break;
+		case _gamepad_analog_button_a:
+		case _gamepad_binary_button_start:
+			/* (the voice chat's switches, kept in config.toml) */
+			if (ui_join_code_globals.selection == 1)
+			{
+				config_write_boolean("voice.enabled", !config_boolean("voice.enabled"));
+				break;
+			}
+			if (ui_join_code_globals.selection == 2)
+			{
+				config_write_boolean("voice.microphone", !config_boolean("voice.microphone"));
+				break;
+			}
+			ui_join_code_globals.panel_open = FALSE;
+			if (ui_join_code_globals.selection == 0 ||
+				ui_join_code_globals.selection >= ui_join_code_globals.game_count + ONLINE_PANEL_FIXED_ROWS)
+			{
+				ui_join_code_launch_keyboard();
+			}
+			else
+			{
+				p2p_join_code_clear_status();
+				p2p_join_with_code(
+					ui_join_code_globals.games[ui_join_code_globals.selection - ONLINE_PANEL_FIXED_ROWS].code);
+			}
+			break;
+		}
+	}
+	if (move)
+	{
+		ui_join_code_globals.selection = (short)PIN(ui_join_code_globals.selection + move, 0, rows - 1);
+		if (ui_join_code_globals.selection < ui_join_code_globals.scroll)
+			ui_join_code_globals.scroll = ui_join_code_globals.selection;
+		else if (ui_join_code_globals.selection >= ui_join_code_globals.scroll + ONLINE_PANEL_ROWS)
+			ui_join_code_globals.scroll = (short)(ui_join_code_globals.selection - ONLINE_PANEL_ROWS + 1);
+	}
+}
+
+/* X on the screen of games to join: the panel of online games (and in it,
+everything); Y in a hosted game's lobby: whether the game is public. TRUE:
+the event is taken. */
+static boolean ui_join_code_take_event(
+	struct widget_instance *widget,
+	struct event_record const *event)
+{
+	if (widget != widget_globals.active_widgets[0])
+		return FALSE;
+	if (ui_join_code_globals.panel_open)
+	{
+		if (!ui_join_code_screen_active("server_list_screen"))
+		{
+			ui_join_code_globals.panel_open = FALSE;
+			return FALSE;
+		}
+		ui_join_code_panel_event(event);
+		return TRUE;
+	}
+	if (event->type != _event_type_button || event->data.button.value != 1)
+		return FALSE;
+	if (event->data.button.index == _gamepad_analog_button_x && ui_join_code_screen_active("server_list_screen"))
+	{
+		ui_join_code_globals.panel_open = TRUE;
+		ui_join_code_globals.selection = 0;
+		ui_join_code_globals.scroll = 0;
+		return TRUE;
+	}
+	if (event->data.button.index == _gamepad_analog_button_y &&
+		ui_join_code_screen_active("connected_pregame_screen") && global_network_game_server_get())
+	{
+		p2p_set_public_game(!p2p_public_game());
+		return TRUE;
+	}
+	return FALSE;
+}
+
+/* the keyboard closed: the code typed, looked up */
+static void ui_join_code_update(
+	void)
+{
+	char text[sizeof(ui_join_code_globals.typed) / sizeof(wchar_t)];
+	short index;
+
+	if (!ui_join_code_globals.keyboard_launched || virtual_keyboard_active())
+		return;
+	ui_join_code_globals.keyboard_launched = FALSE;
+	virtual_keyboard_set_caption(NULL);
+	if (!virtual_keyboard_last_exit_saved_text())
+		return;
+	for (index = 0; index < (short)(NUMBEROF(text) - 1) && ui_join_code_globals.typed[index]; index++)
+	{
+		wchar_t character = ui_join_code_globals.typed[index];
+
+		text[index] = character < 128 ? (char)character : '?';
+	}
+	text[index] = 0;
+	p2p_join_with_code(text);
+}
+
+/* text in bounds, left, right or centred (0, 1, 2) */
+static void ui_join_code_draw_text(
+	short x0,
+	short x1,
+	short y0,
+	char const *text,
+	boolean icons,
+	short justification,
+	real_argb_color const *color)
+{
+	rectangle2d bounds;
+	wchar_t wide[96];
+	short index;
+	long font_index = tag_loaded(FONT_GROUP_TAG, "ui\\small_ui");
+
+	if (font_index == NONE)
+		return;
+	for (index = 0; index < (short)(NUMBEROF(wide) - 1) && text[index]; index++)
+		wide[index] = (wchar_t)(unsigned char)text[index];
+	wide[index] = 0;
+	bounds.y0 = y0;
+	bounds.y1 = (short)(y0 + 20);
+	bounds.x0 = x0;
+	bounds.x1 = x1;
+	draw_string_set_draw_mode(font_index, NONE, justification, 0, color);
+	if (icons)
+		draw_string_and_hack_in_icons(&bounds, &bounds, NULL, 0, wide, FALSE);
+	else
+		rasterizer_draw_unicode_string(&bounds, &bounds, NULL, 0, wide);
+}
+
+static void ui_join_code_draw_line(
+	short y0,
+	char const *text,
+	boolean icons,
+	boolean centered)
+{
+	real_argb_color color = { 1.0f, 0.85f, 0.85f, 0.85f };
+
+	ui_join_code_draw_text((short)(centered ? 0 : 48), (short)(centered ? 640 : 600), y0, text, icons,
+		(short)(centered ? 2 : 0), &color);
+}
+
+static void ui_join_code_draw_quad(
+	short x0,
+	short y0,
+	short x1,
+	short y1,
+	unsigned long color)
+{
+	rectangle2d bounds;
+
+	bounds.x0 = x0;
+	bounds.y0 = y0;
+	bounds.x1 = x1;
+	bounds.y1 = y1;
+	draw_quad(&bounds, color);
+}
+
+/* the panel of online games: "enter a code", then the public games */
+static void ui_join_code_render_panel(
+	void)
+{
+	real_argb_color title_color = { 1.0f, 0.55f, 0.75f, 1.0f };
+	real_argb_color text_color = { 1.0f, 0.85f, 0.85f, 0.85f };
+	real_argb_color dim_color = { 1.0f, 0.6f, 0.6f, 0.6f };
+	char line[64];
+	short row;
+
+	ui_join_code_globals.game_count =
+		(short)p2p_public_games(ui_join_code_globals.games, MAXIMUM_SHOWN_PUBLIC_GAMES);
+	ui_join_code_globals.selection =
+		(short)PIN(ui_join_code_globals.selection, 0, ui_join_code_globals.game_count + ONLINE_PANEL_FIXED_ROWS - 1);
+	ui_join_code_draw_quad(40, 72, 600, 410, 0xF0050A18);
+	ui_join_code_draw_quad(40, 72, 600, 74, 0xFF3A6EA5);
+	ui_join_code_draw_quad(40, 408, 600, 410, 0xFF3A6EA5);
+	snprintf(line, sizeof(line), "ONLINE GAMES (%d public)", (int)ui_join_code_globals.game_count);
+	ui_join_code_draw_text(56, 584, 80, line, FALSE, 0, &title_color);
+	ui_join_code_draw_text(56, 216, 104, "Name", FALSE, 0, &dim_color);
+	ui_join_code_draw_text(216, 376, 104, "Map", FALSE, 0, &dim_color);
+	ui_join_code_draw_text(376, 516, 104, "Game", FALSE, 0, &dim_color);
+	ui_join_code_draw_text(516, 584, 104, "Players", FALSE, 1, &dim_color);
+	for (row = 0; row < ONLINE_PANEL_ROWS; row++)
+	{
+		short index = (short)(ui_join_code_globals.scroll + row);
+		short y = (short)(128 + row * 22);
+
+		if (index >= ui_join_code_globals.game_count + ONLINE_PANEL_FIXED_ROWS)
+			break;
+		if (index == ui_join_code_globals.selection)
+			ui_join_code_draw_quad(48, y, 592, (short)(y + 21), 0x803A6EA5);
+		if (index == 0)
+		{
+			ui_join_code_draw_text(56, 584, (short)(y + 1), "Enter a join code...", FALSE, 0, &text_color);
+		}
+		else if (index == 1)
+		{
+			ui_join_code_draw_text(56, 584, (short)(y + 1),
+				config_boolean("voice.enabled") ? "Voice chat: On" : "Voice chat: Off", FALSE, 0, &text_color);
+		}
+		else if (index == 2)
+		{
+			ui_join_code_draw_text(56, 584, (short)(y + 1),
+				config_boolean("voice.microphone") ? "Microphone: On (sent while you speak)" :
+					"Microphone: Off (listening only)", FALSE, 0, &text_color);
+		}
+		else
+		{
+			struct ui_public_game const *game = &ui_join_code_globals.games[index - ONLINE_PANEL_FIXED_ROWS];
+
+			ui_join_code_draw_text(56, 212, (short)(y + 1), game->name, FALSE, 0, &text_color);
+			ui_join_code_draw_text(216, 372, (short)(y + 1), ui_join_code_map_name(game->map), FALSE, 0,
+				&text_color);
+			ui_join_code_draw_text(376, 512, (short)(y + 1), game->mode, FALSE, 0, &text_color);
+			snprintf(line, sizeof(line), "%d/%d", game->players, game->maximum_players);
+			ui_join_code_draw_text(516, 584, (short)(y + 1), line, FALSE, 1, &text_color);
+		}
+	}
+	if (!ui_join_code_globals.game_count)
+		ui_join_code_draw_text(56, 584, 196, "No public games right now", FALSE, 0, &dim_color);
+	ui_join_code_draw_text(56, 584, 384, "%a-button Join or switch   %x-button Enter a code   %b-button Back", TRUE,
+		0, &text_color);
+}
+
+/* over the screens, as they are drawn */
+static void ui_join_code_render(
+	void)
+{
+	char code[16];
+
+	if (ui_join_code_screen_active("server_list_screen"))
+	{
+		char const *status = NULL;
+
+		if (ui_join_code_globals.panel_open)
+		{
+			ui_join_code_render_panel();
+			return;
+		}
+		ui_join_code_draw_line(372, "%x-button Online games: public ones, or join by a code", TRUE, FALSE);
+		switch (p2p_join_code_status())
+		{
+		case _join_code_looking: status = "Looking for the game of that code..."; break;
+		case _join_code_found: status = "Found it: the game shows up in the list once its host is reached"; break;
+		case _join_code_not_found: status = "No game answered that code"; break;
+		case _join_code_invalid: status = "That is not a join code (8 letters and digits)"; break;
+		case _join_code_own: status = "That is this game's own code"; break;
+		case _join_code_offline: status = "Online play is off (network.online in config.toml)"; break;
+		}
+		/* (the code found, or a link: how reaching its host goes) */
+		if (!status || p2p_join_code_status() == _join_code_found)
+		{
+			switch (p2p_join_state())
+			{
+			case _join_state_reaching: status = "Reaching the online game's host..."; break;
+			case _join_state_connected: status = "Connected: the online game is in the list above"; break;
+			case _join_state_no_answer: status = "The host did not answer: it may have stopped hosting"; break;
+			case _join_state_blocked: status = "Blocked by the routers: allow UPnP on yours or the host's"; break;
+			case _join_state_lost: status = "Lost the connection to the online game's host"; break;
+			}
+		}
+		if (status)
+			ui_join_code_draw_line(392, status, FALSE, FALSE);
+	}
+	else if (ui_join_code_screen_active("connected_pregame_screen") && global_network_game_server_get() &&
+		p2p_join_code(code, sizeof(code)))
+	{
+		char line[96];
+
+		snprintf(line, sizeof(line), "Online join code: %s      %%y-button Public game: %s", code,
+			p2p_public_game() ? "Yes" : "No");
+		/* (under the buttons' key) */
+		ui_join_code_draw_line(448, line, TRUE, TRUE);
+	}
+}
+
 /* whether a menu is up (VR shows it on a screen in the room: render.c) */
 boolean ui_widgets_menus_active(
 	void)
@@ -6045,6 +6468,9 @@ void render_ui_widgets(
 				}
 			}
 		}
+#ifdef HALO_ANDROID
+		ui_join_code_render();
+#endif
 		if (widget_globals.fade_to_black >= 0.0f &&
 			widget_globals.fade_to_black <= 1.0f)
 		{
@@ -6987,6 +7413,9 @@ void process_ui_widgets(
 
 		return;
 	}
+#ifdef HALO_ANDROID
+	ui_join_code_update();
+#endif
 	if (attract_mode_should_start())
 	{
 		attract_mode_start();
@@ -7088,6 +7517,10 @@ void process_ui_widgets(
 			{
 				do
 				{
+#ifdef HALO_ANDROID
+					if (ui_join_code_take_event(widget, &event))
+						continue;
+#endif
 					if (!pause_pressed)
 					{
 						widget_instance_process_one_event_recursive(

source/interface/virtual_keyboard.c

@@ -96,6 +96,18 @@ symbols in this file:
 #include "text/text_group.h"
 #include "text/unicode.h"
 
+#ifdef HALO_ANDROID
+/* the VR port's: a caption of its own instead of the string list's, for a
+keyboard it launches (ui_widget.c's join codes); NULL for the list's */
+static wchar_t const *virtual_keyboard_caption_override;
+
+void virtual_keyboard_set_caption(
+	wchar_t const *caption)
+{
+	virtual_keyboard_caption_override = caption;
+}
+#endif
+
 /* ---------- constants */
 
 enum
@@ -671,6 +683,10 @@ static void virtual_keyboard_render_internal(
 		wchar_t *caption = unicode_string_list_get_string(
 			virtual_keyboard_globals.keyboard->special_key_labels_string_list_tag.index,
 			virtual_keyboard_globals.caption_index);
+#ifdef HALO_ANDROID
+		if (virtual_keyboard_caption_override)
+			caption = (wchar_t *)virtual_keyboard_caption_override;
+#endif
 
 		bounds.y0 = 78;
 		bounds.x0 = 114;

source/interface/virtual_keyboard.h

@@ -38,6 +38,10 @@ void virtual_keyboard_process(
 	void);
 void virtual_keyboard_render(
 	void);
+#ifdef HALO_ANDROID
+void virtual_keyboard_set_caption(
+	wchar_t const *caption);
+#endif
 
 /* ---------- globals */
 

source/networking/network_server_manager.c

@@ -475,6 +475,10 @@ symbols in this file:
 
 /* port: internet play's Discord presence (port/linux/src/p2p.c) */
 void p2p_set_game_player_counts(int count, int maximum);
+#ifdef HALO_ANDROID
+void p2p_set_game_description(char const *name, char const *map, char const *mode, int players,
+	int maximum_players);
+#endif
 
 /* ---------- constants */
 
@@ -1308,6 +1312,42 @@ boolean network_game_server_idle(
 
 	/* (what Discord shows of a game hosted for internet play) */
 	p2p_set_game_player_counts(server->game.player_count, server->game.maximum_players);
+#ifdef HALO_ANDROID
+	/* (and what a public game's listing says: port/linux/src/p2p_list.c) */
+	{
+		char name[16], map[32], mode[24];
+		char const *map_name = server->game.map.name;
+		char const *separator;
+		short index;
+
+		for (index = 0; index < (short)(NUMBEROF(name) - 1) && server->game.name[index]; index++)
+			name[index] = server->game.name[index] < 128 ? (char)server->game.name[index] : '?';
+		name[index] = 0;
+		/* (the scenario's name, the last of its path) */
+		while ((separator = strpbrk(map_name, "\\/")) != NULL)
+			map_name = separator + 1;
+		csstrncpy(map, map_name, sizeof(map) - 1);
+		map[sizeof(map) - 1] = 0;
+		for (index = 0; index < (short)(NUMBEROF(mode) - 1) && index < 12 &&
+			server->game.variant.human_readable_game_description[index]; index++)
+		{
+			wchar_t character = server->game.variant.human_readable_game_description[index];
+
+			mode[index] = character < 128 ? (char)character : '?';
+		}
+		mode[index] = 0;
+		/* (a game type without a name of its own: its kind's) */
+		if (!mode[0])
+		{
+			static char const *const kinds[] = { "", "CTF", "Slayer", "Oddball", "King of the Hill", "Race" };
+			long kind = server->game.variant.game_engine_index;
+
+			csstrncpy(mode, kind > 0 && kind < (long)NUMBEROF(kinds) ? kinds[kind] : "Custom", sizeof(mode) - 1);
+			mode[sizeof(mode) - 1] = 0;
+		}
+		p2p_set_game_description(name, map, mode, server->game.player_count, server->game.maximum_players);
+	}
+#endif
 
 	if (network_game_server_game_is_valid(server))
 	{

tools/android_build.py

@@ -44,6 +44,10 @@ MUSL_URL = f"https://musl.libc.org/releases/musl-{MUSL_VERSION}.tar.gz"
 SDL_TAG = "release-3.4.16"
 SDL_DIR = THIRD_PARTY / "SDL3"
 SDL_URL = "https://github.com/libsdl-org/SDL.git"
+# Opus, the voice chat's codec (host_voice.c), built into the host library
+OPUS_TAG = "v1.5.2"
+OPUS_DIR = THIRD_PARTY / "opus"
+OPUS_URL = "https://github.com/xiph/opus.git"
 # the Khronos OpenXR loader for Android (the VR build, host_xr.c): its
 # headers and library are linked from here; the app packages the same AAR
 # through Gradle (port/android/app/build.gradle), which also merges the
@@ -178,6 +182,10 @@ def fetch_third_party() -> None:
         print(f"Cloning SDL3 {SDL_TAG}")
         subprocess.run(["git", "clone", "-q", "--depth", "1", "--branch", SDL_TAG, SDL_URL, str(SDL_DIR)],
                        check=True)
+    if not OPUS_DIR.is_dir():
+        print(f"Cloning Opus {OPUS_TAG}")
+        subprocess.run(["git", "clone", "-q", "--depth", "1", "--branch", OPUS_TAG, OPUS_URL, str(OPUS_DIR)],
+                       check=True)
     if not OPENXR_DIR.is_dir():
         print(f"Downloading {OPENXR_URL}")
         import zipfile
@@ -509,6 +517,23 @@ def generate_android_build(n: Writer, sln: Any) -> None:
     )
     n.build(outputs=libsdl, rule="android_sdl3", implicit=[SDL_DIR / "CMakeLists.txt"])
 
+    # ---------- Opus (the voice chat's codec, host_voice.c)
+
+    opus_build = BUILD / "opus-build"
+    libopus = opus_build / "libopus.a"
+    n.rule(
+        name="android_opus",
+        command=(f"cmake -S {OPUS_DIR} -B {opus_build} -G Ninja "
+                 f"-DCMAKE_TOOLCHAIN_FILE={ndk}/build/cmake/android.toolchain.cmake "
+                 f"-DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-{ANDROID_API} -DCMAKE_BUILD_TYPE=Release "
+                 f"-DCMAKE_POSITION_INDEPENDENT_CODE=ON -DOPUS_BUILD_SHARED_LIBRARY=OFF -DOPUS_BUILD_TESTING=OFF "
+                 f"-DOPUS_BUILD_PROGRAMS=OFF -DOPUS_INSTALL_PKG_CONFIG_MODULE=OFF -DOPUS_INSTALL_CMAKE_CONFIG_MODULE=OFF "
+                 f"> {BUILD}/opus-configure.log && ninja -C {opus_build} > {BUILD}/opus-build.log"),
+        description="ANDROID OPUS",
+        pool="console",
+    )
+    n.build(outputs=libopus, rule="android_opus", implicit=[OPUS_DIR / "CMakeLists.txt"])
+
     # ---------- the host library
 
     host_objects: List[Path] = []
@@ -523,7 +548,7 @@ def generate_android_build(n: Writer, sln: Any) -> None:
     host_cflags = " ".join([
         "-O2", "-g", "-fPIC", "-Wall", "-Wno-unused-function", "-D_GNU_SOURCE",
         f"-I{PORT_DIR}/include", f"-I{PORT_DIR}/host", f"-I{SDL_DIR}/include", f"-I{LINUX_DIR}/src",
-        f"-I{TOML_DIR}", f"-I{OPENXR_DIR}/include",
+        f"-I{TOML_DIR}", f"-I{OPENXR_DIR}/include", f"-I{OPUS_DIR}/include",
     ])
     host_sources = sorted((PORT_DIR / "host").glob("*.c")) + [
         LINUX_DIR / "src" / "posix_files.c", LINUX_DIR / "src" / "posix_net.c",
@@ -549,12 +574,12 @@ def generate_android_build(n: Writer, sln: Any) -> None:
     host_objects.append(table_obj)
     n.rule(
         name="android_host_link",
-        command=(f"$android_host_cc -shared -o $out $in -L{sdl_build} -L{OPENXR_DIR}/lib -lopenxr_loader "
+        command=(f"$android_host_cc -shared -o $out $in {libopus} -L{sdl_build} -L{OPENXR_DIR}/lib -lopenxr_loader "
                  + " ".join(f"-l{lib}" for lib in HOST_LIBRARIES)
                  + " -Wl,-z,max-page-size=16384 -Wl,--no-undefined"),
         description="ANDROID HOST LINK $out",
     )
-    n.build(outputs=libmain, rule="android_host_link", inputs=host_objects, implicit=[libsdl])
+    n.build(outputs=libmain, rule="android_host_link", inputs=host_objects, implicit=[libsdl, libopus])
 
     # ---------- staging for Gradle