Networking: don't enable TFO if server doesn't support it

src/common/networking/networking.h

@@ -26,6 +26,7 @@ typedef struct FFNetworkingState {
     uint32_t timeout;
     bool ipv6;
     bool compression; // if true, HTTP content compression will be enabled if supported
+    bool tfo; // if true, TCP Fast Open will be attempted first, and fallback to traditional connection if it fails
 } FFNetworkingState;
 
 const char* ffNetworkingSendHttpRequest(FFNetworkingState* state, const char* host, const char* path, const char* headers);

src/common/networking/networking_linux.c

@@ -19,7 +19,17 @@
 // Try to use TCP Fast Open to send data
 static const char* tryTcpFastOpen(FFNetworkingState* state)
 {
-    #if !defined(TCP_FASTOPEN) || (defined(__linux__) && !defined(MSG_FASTOPEN))
+    if (!state->tfo)
+    {
+        #ifndef __APPLE__
+        FF_DEBUG("TCP Fast Open disabled, skipping");
+        return "TCP Fast Open disabled";
+        #else
+        FF_DEBUG("TCP Fast Open disabled, using connectx() to send data");
+        #endif
+    }
+
+    #if (!defined(__APPLE__) && !defined(TCP_FASTOPEN)) || (defined(__linux__) && !defined(MSG_FASTOPEN))
         FF_DEBUG("TCP Fast Open not supported on this system");
         FF_UNUSED(state);
         return "TCP Fast Open not supported";
@@ -81,7 +91,7 @@ static const char* tryTcpFastOpen(FFNetworkingState* state)
                 .sae_dstaddr = state->addr->ai_addr,
                 .sae_dstaddrlen = state->addr->ai_addrlen,
             },
-            SAE_ASSOCID_ANY, CONNECT_DATA_IDEMPOTENT,
+            SAE_ASSOCID_ANY, state->tfo ? CONNECT_DATA_IDEMPOTENT : 0,
             &(struct iovec) {
                 .iov_base = state->command.chars,
                 .iov_len = state->command.length,
@@ -91,31 +101,40 @@ static const char* tryTcpFastOpen(FFNetworkingState* state)
             return "fcntl(F_SETFL) failed";
         }
         #endif
-        if (sent >= 0 || (errno == EAGAIN || errno == EWOULDBLOCK))
+        if (sent > 0 || (errno == EAGAIN || errno == EWOULDBLOCK
+            #ifdef __APPLE__
+            // On macOS EINPROGRESS means the connection cannot be completed immediately
+            // On Linux, it means the TFO cookie is not available locally
+            || errno == EINPROGRESS
+            #endif
+        ))
         {
-            FF_DEBUG("TCP Fast Open %s (sent=%zd, errno=%d: %s)", errno == 0 ? "succeeded" : "was in progress",
-                     sent, errno, strerror(errno));
+            FF_DEBUG(
+                #ifdef __APPLE__
+                "connectx()"
+                #else
+                "sendto()"
+                #endif
+                " %s (sent=%zd, errno=%d: %s)", errno == 0 ? "succeeded" : "was in progress",
+                sent, errno, strerror(errno));
             freeaddrinfo(state->addr);
             state->addr = NULL;
             ffStrbufDestroy(&state->command);
             return NULL;
         }
 
-        if (errno == EINPROGRESS)
-        {
-            FF_DEBUG("TCP Fast Open cookie is not available locally");
-            return "sendto() reports EINPROGRESS";
-        }
-        else
-        {
-            // Fast Open failed
-            FF_DEBUG("TCP Fast Open failed: %s (errno=%d)", strerror(errno), errno);
+        FF_DEBUG(
             #ifdef __APPLE__
-            return "connectx() failed";
+            "connectx()"
             #else
-            return "sendto() failed";
+            "sendto()"
             #endif
-        }
+            " failed: %s (errno=%d)", strerror(errno), errno);
+        #ifdef __APPLE__
+        return "connectx() failed";
+        #else
+        return "sendto() failed";
+        #endif
     #endif
 }
 
@@ -316,10 +335,10 @@ const char* ffNetworkingSendHttpRequest(FFNetworkingState* state, const char* ho
 
     const char* tfoResult = tryTcpFastOpen(state);
     if (tfoResult == NULL) {
-        FF_DEBUG("TCP Fast Open succeeded or in progress");
+        FF_DEBUG("TryTcpFastOpen succeeded or in progress");
         return NULL;
     }
-    FF_DEBUG("TCP Fast Open unavailable or failed: %s, trying traditional connection", tfoResult);
+    FF_DEBUG("TryTcpFastOpen failed: %s, trying traditional connection", tfoResult);
 
     #ifdef FF_HAVE_THREADS
     if (instance.config.general.multithreading)

src/common/networking/networking_windows.c

@@ -166,12 +166,19 @@ const char* ffNetworkingSendHttpRequest(FFNetworkingState* state, const char* ho
     ffStrbufAppendS(&command, "\r\n");
 
     #ifdef TCP_FASTOPEN
-    // Set TCP Fast Open
-    flag = 1;
-    if (setsockopt(state->sockfd, IPPROTO_TCP, TCP_FASTOPEN, (char*)&flag, sizeof(flag)) != 0) {
-        FF_DEBUG("Failed to set TCP_FASTOPEN option: %s", ffDebugWin32Error((DWORD) WSAGetLastError()));
-    } else {
-        FF_DEBUG("Successfully set TCP_FASTOPEN option");
+    if (state->tfo)
+    {
+        // Set TCP Fast Open
+        flag = 1;
+        if (setsockopt(state->sockfd, IPPROTO_TCP, TCP_FASTOPEN, (char*)&flag, sizeof(flag)) != 0) {
+            FF_DEBUG("Failed to set TCP_FASTOPEN option: %s", ffDebugWin32Error((DWORD) WSAGetLastError()));
+        } else {
+            FF_DEBUG("Successfully set TCP_FASTOPEN option");
+        }
+    }
+    else
+    {
+        FF_DEBUG("TCP Fast Open disabled");
     }
     #endif
 
@@ -181,6 +188,7 @@ const char* ffNetworkingSendHttpRequest(FFNetworkingState* state, const char* ho
                           command.chars, command.length, &sent, &state->overlapped);
 
     freeaddrinfo(addr);
+    addr = NULL;
 
     if(!result)
     {

src/detection/publicip/publicip.c

@@ -21,6 +21,7 @@ void ffPreparePublicIp(FFPublicIpOptions* options)
     if (options->url.length == 0)
     {
         state->compression = true;
+        state->tfo = true;
         *status = ffNetworkingSendHttpRequest(state, options->ipv6 ? "v6.ipinfo.io" : "ipinfo.io", "/json", NULL);
     }
     else