Join online games with a short code in VR

A hosted game gets an 8-character join code (Crockford base 32) besides
its invite link, shown under the lobby's buttons. On the system link list,
X opens the game's keyboard to type a code in; the code's topic and key
come from a slow PBKDF2 derivation, the host answers an ask on that topic
through the signalling brokers with its invite sealed with the key, and
the joiner joins as with the link. Codes in join_link.txt work too.

Also: the clipboard text last seen is kept from run to run, so a run's
own invite is not joined again at the next start; in menus a held stick
repeats after 350 ms and then every 90 ms, and its threshold is 70%.

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

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/src/p2p.c

@@ -2314,10 +2314,48 @@ 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_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");
 }
 
@@ -2382,6 +2420,14 @@ 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 +2442,7 @@ 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 +26,24 @@ 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);
+
 /* 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 +107,34 @@ 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);
+
+/* ---------- 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_crypto.c */
 

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 +154,9 @@ 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];
 	unsigned char input[BUFFER_SIZE];
 	int input_size;
 	unsigned char output[BUFFER_SIZE];
@@ -321,6 +326,8 @@ 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;
 	if (failed)
 		broker->failures++;
 }
@@ -410,17 +417,20 @@ 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[4];
+	char *had[4];
 	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]);
 	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;
+	for (index = 0; index < 4; index++)
 	{
 		if (!strcmp(wanted[index], had[index]))
 			continue;
@@ -939,6 +949,8 @@ 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))
+		return;
 	if (signalling.hosting && !strcmp(topic, signalling.host_topic))
 	{
 		message_size = p2p_open(signalling.host_key, payload, size, message);
@@ -1190,6 +1202,7 @@ 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();
 }
 
 int p2p_signal_connected(void)
@@ -1212,6 +1225,17 @@ 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_host(const unsigned char *token)
 {
 	if (!signalling.has_nonce_key)

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))

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 +5591,152 @@ 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): the host's lobby
+shows its game's code, and on the screen of games to join, X opens the
+keyboard to type one in, 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);
+
+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,
+};
+
+static struct
+{
+	boolean keyboard_launched;
+	wchar_t typed[12];
+} ui_join_code_globals;
+
+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;
+}
+
+/* X on the screen of games to join: the keyboard, for a code (TRUE: the
+event is taken) */
+static boolean ui_join_code_take_event(
+	struct widget_instance *widget,
+	struct event_record const *event)
+{
+	if (event->type != _event_type_button || event->data.button.value != 1 ||
+		event->data.button.index != _gamepad_analog_button_x || widget != widget_globals.active_widgets[0] ||
+		!ui_join_code_screen_active("server_list_screen"))
+	{
+		return FALSE;
+	}
+	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 FALSE;
+	}
+	p2p_join_code_clear_status();
+	ui_join_code_globals.keyboard_launched = TRUE;
+	return TRUE;
+}
+
+/* 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);
+}
+
+static void ui_join_code_draw_line(
+	short y0,
+	char const *text,
+	boolean icons,
+	boolean centered)
+{
+	rectangle2d bounds;
+	wchar_t wide[96];
+	short index;
+	long font_index = tag_loaded(FONT_GROUP_TAG, "ui\\small_ui");
+	real_argb_color color = { 1.0f, 0.85f, 0.85f, 0.85f };
+
+	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 = centered ? 0 : 48;
+	bounds.x1 = centered ? 640 : 600;
+	draw_string_set_draw_mode(font_index, NONE, centered ? 2 : 0, 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);
+}
+
+/* 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;
+
+		ui_join_code_draw_line(372, "%x-button Join an online game with its 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;
+		}
+		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[48];
+
+		snprintf(line, sizeof(line), "Online join code: %s", code);
+		/* (under the buttons' key) */
+		ui_join_code_draw_line(448, line, FALSE, 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 +6191,9 @@ 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 +7136,9 @@ void process_ui_widgets(
 
 		return;
 	}
+#ifdef HALO_ANDROID
+	ui_join_code_update();
+#endif
 	if (attract_mode_should_start())
 	{
 		attract_mode_start();
@@ -7088,6 +7240,10 @@ 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 */