From 3aae4cdc595ff6f428a2abbfb9d5055c03423bc2 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Fri, 22 Dec 2023 13:45:50 -0600
Subject: [PATCH] Improve ENet socket error propagation for better
 debuggability

---
 src/ControlStream.c  | 4 ++++
 src/Misc.c           | 7 ++++++-
 src/RtspConnection.c | 6 +++---
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/ControlStream.c b/src/ControlStream.c
index 7be88b6..a332798 100644
--- a/src/ControlStream.c
+++ b/src/ControlStream.c
@@ -1068,6 +1068,10 @@ static void controlReceiveThreadFunc(void* context) {
         }
 
         if (err < 0) {
+            // The error from serviceEnetHost() should be propagated via LastSocketError()
+            LC_ASSERT(err == -1);
+
+            err = LastSocketFail();
             Limelog("Control stream connection failed: %d\n", err);
             ListenerCallbacks.connectionTerminated(err);
             return;
diff --git a/src/Misc.c b/src/Misc.c
index 0df1ffc..4988b12 100644
--- a/src/Misc.c
+++ b/src/Misc.c
@@ -9,6 +9,10 @@
 static int serviceEnetHostInternal(ENetHost* client, ENetEvent* event, enet_uint32 timeoutMs, bool ignoreInterrupts) {
     int ret;
 
+    // Clear the last socket error to ensure the caller doesn't read a stale error upon a
+    // failure in non-socket-related processing in enet_host_service()
+    SetLastSocketError(0);
+
     // We need to call enet_host_service() multiple times to make sure retransmissions happen
     for (;;) {
         int selectedTimeout = timeoutMs < ENET_INTERNAL_TIMEOUT_MS ? timeoutMs : ENET_INTERNAL_TIMEOUT_MS;
@@ -16,6 +20,7 @@ static int serviceEnetHostInternal(ENetHost* client, ENetEvent* event, enet_uint
         // We want to report an interrupt event if we are able to read data
         if (!ignoreInterrupts && ConnectionInterrupted) {
             Limelog("ENet wait interrupted\n");
+            SetLastSocketError(EINTR);
             ret = -1;
             break;
         }
@@ -67,7 +72,7 @@ int gracefullyDisconnectEnetPeer(ENetHost* host, ENetPeer* peer, enet_uint32 lin
             Limelog("Timed out waiting for ENet peer to acknowledge disconnection\n");
         }
         else {
-            Limelog("Failed to receive ENet peer disconnection acknowledgement\n");
+            Limelog("Failed to receive ENet peer disconnection acknowledgement: %d\n", LastSocketFail());
         }
 
         return -1;
diff --git a/src/RtspConnection.c b/src/RtspConnection.c
index 4e16479..e94bb52 100644
--- a/src/RtspConnection.c
+++ b/src/RtspConnection.c
@@ -144,7 +144,7 @@ static bool transactRtspMessageEnet(PRTSP_MESSAGE request, PRTSP_MESSAGE respons
     // Wait for a reply
     if (serviceEnetHost(client, &event, RTSP_RECEIVE_TIMEOUT_SEC * 1000) <= 0 ||
         event.type != ENET_EVENT_TYPE_RECEIVE) {
-        Limelog("Failed to receive RTSP reply\n");
+        Limelog("Failed to receive RTSP reply: %d\n", LastSocketFail());
         goto Exit;
     }
 
@@ -165,7 +165,7 @@ static bool transactRtspMessageEnet(PRTSP_MESSAGE request, PRTSP_MESSAGE respons
         // The payload comes in a second packet
         if (serviceEnetHost(client, &event, RTSP_RECEIVE_TIMEOUT_SEC * 1000) <= 0 ||
             event.type != ENET_EVENT_TYPE_RECEIVE) {
-            Limelog("Failed to receive RTSP reply payload\n");
+            Limelog("Failed to receive RTSP reply payload: %d\n", LastSocketFail());
             goto Exit;
         }
 
@@ -851,7 +851,7 @@ int performRtspHandshake(PSERVER_INFORMATION serverInfo) {
         // Wait for the connect to complete
         if (serviceEnetHost(client, &event, RTSP_CONNECT_TIMEOUT_SEC * 1000) <= 0 ||
             event.type != ENET_EVENT_TYPE_CONNECT) {
-            Limelog("RTSP: Failed to connect to UDP port %u\n", RtspPortNumber);
+            Limelog("RTSP: Failed to connect to UDP port %u: error %d\n", RtspPortNumber, LastSocketFail());
             enet_peer_reset(peer);
             peer = NULL;
             enet_host_destroy(client);