ws2_32: Enable IP_DONTFRAGMENT by default for SOCK_STREAM sockets.

dlls/ws2_32/socket.c

@@ -7606,9 +7606,14 @@ SOCKET WINAPI WSASocketW(int af, int type, int protocol,
         if (ipxptype > 0)
             set_ipx_packettype(ret, ipxptype);
 
-        /* ensure IP_DONTFRAGMENT is disabled, in Linux the global default can be enabled */
         if (unixaf == AF_INET || unixaf == AF_INET6)
+        {
+            /* ensure IP_DONTFRAGMENT is disabled for SOCK_DGRAM and SOCK_RAW, enabled for SOCK_STREAM */
+            if (unixtype == SOCK_DGRAM || unixtype == SOCK_RAW) /* in Linux the global default can be enabled */
                 set_dont_fragment(ret, unixaf == AF_INET6 ? IPPROTO_IPV6 : IPPROTO_IP, FALSE);
+            else if (unixtype == SOCK_STREAM)
+                set_dont_fragment(ret, unixaf == AF_INET6 ? IPPROTO_IPV6 : IPPROTO_IP, TRUE);
+        }
 
 #ifdef IPV6_V6ONLY
         if (unixaf == AF_INET6)

dlls/ws2_32/tests/sock.c

@@ -1908,6 +1908,59 @@ todo_wine
         ok(value == 1, "Expected 1, got %d\n", value);
 
         closesocket(s);
+
+        s = socket(family, SOCK_STREAM, 0);
+        if (s == INVALID_SOCKET && i)
+        {
+            skip("IPv6 is not supported\n");
+            break;
+        }
+        ok(s != INVALID_SOCKET, "socket failed with error %d\n", GetLastError());
+
+        size = sizeof(value);
+        value = 0xdead;
+        err = getsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, &size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+        ok(value == 1 || broken(value == 0) /* < vista */, "Expected 1, got %d\n", value);
+
+        size = sizeof(value);
+        value = 0;
+        err = setsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+
+        value = 0xdead;
+        err = getsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, &size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+        ok(value == 0, "Expected 0, got %d\n", value);
+
+        closesocket(s);
+
+        s = socket(family, SOCK_RAW, 0);
+        if (s == INVALID_SOCKET)
+        {
+            if (WSAGetLastError() == WSAEACCES) skip("SOCK_RAW is not available\n");
+            else if (i) skip("IPv6 is not supported\n");
+            break;
+        }
+        ok(s != INVALID_SOCKET, "socket failed with error %d\n", GetLastError());
+
+        size = sizeof(value);
+        value = 0xdead;
+        err = getsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, &size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+        ok(value == 0, "Expected 0, got %d\n", value);
+
+        size = sizeof(value);
+        value = 1;
+        err = setsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+
+        value = 0xdead;
+        err = getsockopt(s, level, IP_DONTFRAGMENT, (char *) &value, &size);
+        ok(!err, "Expected 0, got %d with error %d\n", err, GetLastError());
+        ok(value == 1, "Expected 1, got %d\n", value);
+
+        closesocket(s);
     }
 }