From 67c29c62b0c00c152b39e8710a2b1ae53814339a Mon Sep 17 00:00:00 2001
From: Wit <58151178+Wit-MKW@users.noreply.github.com>
Date: Tue, 24 Jun 2025 19:21:38 -0400
Subject: [PATCH 1/2] update P2P synchronisation
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the P2P features of Zero Tours only work in one direction at a time, so it won't do to only receive as many packets as are sent; in fact, it seems that this was never the issue with Pokémon. rather, the issue with Pokémon was that it was receiving a low-level error on remote disconnect, which isn't even a detectable state when the connection is over a phone line. rather, we simply stop sending the game data, allowing it to detect the remote disconnect through a timeout or other method which, to reiterate, was necessary in '01/'02 when these games were connecting over a phone line.
---
 commands.c | 33 +++++++++------------------------
 commands.h |  1 -
 2 files changed, 9 insertions(+), 25 deletions(-)

diff --git a/commands.c b/commands.c
index bcb9767..9d14acf 100644
--- a/commands.c
+++ b/commands.c
@@ -325,7 +325,6 @@ static struct mobile_packet *command_tel_ip(struct mobile_adapter *adapter, stru
     }
 
     s->state = MOBILE_CONNECTION_CALL;
-    s->call_packets_sent = 0;
 
     packet->length = 0;
     return packet;
@@ -361,7 +360,6 @@ static struct mobile_packet *command_tel_relay(struct mobile_adapter *adapter, s
     }
 
     s->state = MOBILE_CONNECTION_CALL;
-    s->call_packets_sent = 0;
 
     packet->length = 0;
     return packet;
@@ -464,7 +462,6 @@ static struct mobile_packet *command_wait_call_ip(struct mobile_adapter *adapter
     if (!mobile_cb_sock_accept(adapter, 0)) return NULL;
 
     s->state = MOBILE_CONNECTION_CALL_RECV;
-    s->call_packets_sent = 0;
 
     packet->length = 0;
     return packet;
@@ -500,7 +497,6 @@ static struct mobile_packet *command_wait_call_relay(struct mobile_adapter *adap
     }
 
     s->state = MOBILE_CONNECTION_CALL_RECV;
-    s->call_packets_sent = 0;
 
     packet->length = 0;
     return packet;
@@ -625,31 +621,20 @@ static struct mobile_packet *command_data(struct mobile_adapter *adapter, struct
             }
             return NULL;
         }
-
-        // Pokémon Crystal expects communications to be "synchronized".
-        // For this, we only try to receive packets when we've sent one.
-        // TODO: Check other games with peer to peer functionality.
-        if (!internet) {
-            if (s->call_packets_sent < 0xFF) s->call_packets_sent++;
-        }
     }
 
-    int recv_size = 0;
-    if (internet || s->call_packets_sent) {
-        recv_size = mobile_cb_sock_recv(adapter, conn, data,
-            MOBILE_MAX_TRANSFER_SIZE, NULL);
-    }
+    int recv_size = mobile_cb_sock_recv(adapter, conn, data,
+        MOBILE_MAX_TRANSFER_SIZE, NULL);
 
-    if (!internet && recv_size > 0) {
-        if (s->call_packets_sent > 0) s->call_packets_sent--;
-    }
-
-    // If connected to the internet, and a disconnect is received, we should
-    // inform the game about a remote disconnect.
-    if (internet && recv_size == -2) {
+    if (recv_size == -2) {
         mobile_cb_sock_close(adapter, conn);
         s->connections[conn] = false;
-        packet->command = MOBILE_COMMAND_DATA_END;
+
+        // If connected to the internet, and a disconnect is received, we
+        // should inform the game about a remote disconnect.
+        if (internet) {
+            packet->command = MOBILE_COMMAND_DATA_END;
+        }
         packet->length = 1;
         return packet;
     }
diff --git a/commands.h b/commands.h
index 7005686..d9aaa01 100644
--- a/commands.h
+++ b/commands.h
@@ -65,7 +65,6 @@ struct mobile_adapter_commands {
     enum mobile_connection_state state;
     bool connections[MOBILE_MAX_CONNECTIONS];
     bool dns2_use;
-    unsigned char call_packets_sent;
     struct mobile_addr4 dns1;
     struct mobile_addr4 dns2;
 };

From 0704f56902f23b7ebf05c82c222e0e145e3140b6 Mon Sep 17 00:00:00 2001
From: Wit <58151178+Wit-MKW@users.noreply.github.com>
Date: Wed, 25 Jun 2025 01:59:45 -0400
Subject: [PATCH 2/2] keep P2P socket open on remote disconnect

this allows for games not to notice a remote disconnect right away, at the expense of calling `sock_recv` one or more times after a remote disconnect.
---
 commands.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/commands.c b/commands.c
index 9d14acf..7b99118 100644
--- a/commands.c
+++ b/commands.c
@@ -627,12 +627,11 @@ static struct mobile_packet *command_data(struct mobile_adapter *adapter, struct
         MOBILE_MAX_TRANSFER_SIZE, NULL);
 
     if (recv_size == -2) {
-        mobile_cb_sock_close(adapter, conn);
-        s->connections[conn] = false;
-
         // If connected to the internet, and a disconnect is received, we
         // should inform the game about a remote disconnect.
         if (internet) {
+            mobile_cb_sock_close(adapter, conn);
+            s->connections[conn] = false;
             packet->command = MOBILE_COMMAND_DATA_END;
         }
         packet->length = 1;