1 files changed, 26 insertions, 15 deletions

diff --git a/src/btfrv.cpp b/src/btfrv.cpp
index d4f079f..133eb89 100644
--- a/src/btfrv.cpp
+++ b/src/btfrv.cpp
@@ -102,31 +102,42 @@ static SOCKET ConnectTo(const char* host, unsigned short port)
 #else
     struct addrinfo hints, *res = NULL;
     memset(&hints, 0, sizeof(hints));
-    hints.ai_family = AF_INET;
+    hints.ai_family = AF_UNSPEC; // IPv4 or IPv6 (some relays are v6-only)
     hints.ai_socktype = SOCK_STREAM;
     char portstr[16]; sprintf(portstr, "%u", (unsigned)port);
     if (getaddrinfo(host, portstr, &hints, &res) != 0 || !res) return INVALID_SOCKET;
-    SOCKET s = BtfSocketTag(socket(res->ai_family, res->ai_socktype, res->ai_protocol), SOCK_RV_DIAL);
-    if (s == INVALID_SOCKET) { freeaddrinfo(res); return INVALID_SOCKET; }
 
-    // Apply a short timeout only for the connect() and initial handshake so an
-    // unresponsive relay doesn't block the thread. Once the tunnel is live the
-    // timeout is cleared -- a forwarding pipe must block indefinitely on recv().
+    // Try each resolved address until one connects.
+    SOCKET s = INVALID_SOCKET;
+    for (struct addrinfo* rp = res; rp != NULL; rp = rp->ai_next)
+    {
+        s = BtfSocketTag(socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol), SOCK_RV_DIAL);
+        if (s == INVALID_SOCKET)
+            continue;
+
+        // Apply a short timeout only for the connect() and initial handshake so an
+        // unresponsive relay doesn't block the thread. Once the tunnel is live the
+        // timeout is cleared -- a forwarding pipe must block indefinitely on recv().
 #ifdef _WIN32
-    DWORD tvShort = 10000;
-    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tvShort, sizeof(tvShort));
-    setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, (const char*)&tvShort, sizeof(tvShort));
+        DWORD tvShort = 10000;
+        setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tvShort, sizeof(tvShort));
+        setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, (const char*)&tvShort, sizeof(tvShort));
 #else
-    struct timeval tvShort; tvShort.tv_sec = 10; tvShort.tv_usec = 0;
-    setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tvShort, sizeof(tvShort));
-    setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, &tvShort, sizeof(tvShort));
+        struct timeval tvShort; tvShort.tv_sec = 10; tvShort.tv_usec = 0;
+        setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, (char*)&tvShort, sizeof(tvShort));
+        setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, (char*)&tvShort, sizeof(tvShort));
 #endif
 
-    if (connect(s, res->ai_addr, (int)res->ai_addrlen) != 0)
-    {
-        CLOSESOCK(s); freeaddrinfo(res); return INVALID_SOCKET;
+        if (connect(s, rp->ai_addr, (int)rp->ai_addrlen) != 0)
+        {
+            CLOSESOCK(s);
+            s = INVALID_SOCKET;
+            continue;
+        }
+        break;
     }
     freeaddrinfo(res);
+    if (s == INVALID_SOCKET) return INVALID_SOCKET;
 #endif
 
     // Clear the timeout -- the socket is now a live tunnel and must not