ws2_32: WSARecvMsg allows a NULL control buffer when no control messages arrive.

dlls/ws2_32/socket.c

@@ -878,10 +878,12 @@ static inline int convert_control_headers(struct msghdr *hdr, WSABUF *control)
         }
     }
 
-error:
     /* Set the length of the returned control headers */
-    control->len = (ptr == NULL ? 0 : (char*)ptr - (char*)cmsg_win);
-    return (ptr != NULL);
+    control->len = (char*)ptr - (char*)cmsg_win;
+    return 1;
+error:
+    control->len = 0;
+    return 0;
 #else /* IP_PKTINFO */
     control->len = 0;
     return 1;

dlls/ws2_32/tests/sock.c

@@ -2108,8 +2108,6 @@ static void test_ip_pktinfo(void)
         /* Setup the server side socket */
         rc=bind(s1, (struct sockaddr*)&s1addr, sizeof(s1addr));
         ok(rc != SOCKET_ERROR, "bind() failed error: %d\n", WSAGetLastError());
-        rc=setsockopt(s1, IPPROTO_IP, IP_PKTINFO, (const char*)&yes, sizeof(yes));
-        ok(rc == 0, "failed to set IPPROTO_IP flag IP_PKTINFO!\n");
 
         /* Build "client" side socket */
         addrlen = sizeof(s2addr);
@@ -2133,6 +2131,21 @@ static void test_ip_pktinfo(void)
         err=WSAGetLastError();
         ok(rc == SOCKET_ERROR && err == WSAEFAULT, "WSARecvMsg() failed error: %d (ret = %d)\n", err, rc);
 
+        /* Test that when no control data arrives, a 0-length NULL-valued control buffer should succeed */
+        SetLastError(0xdeadbeef);
+        rc=sendto(s2, msg, sizeof(msg), 0, (struct sockaddr*)&s2addr, sizeof(s2addr));
+        ok(rc == sizeof(msg), "sendto() failed error: %d\n", WSAGetLastError());
+        ok(GetLastError() == ERROR_SUCCESS, "Expected 0, got %d\n", GetLastError());
+        hdr.Control.buf = NULL;
+        hdr.Control.len = 0;
+        rc=pWSARecvMsg(s1, &hdr, &dwSize, NULL, NULL);
+        ok(rc == 0, "WSARecvMsg() failed error: %d\n", WSAGetLastError());
+        hdr.Control.buf = pktbuf;
+
+        /* Now start IP_PKTINFO for future tests */
+        rc=setsockopt(s1, IPPROTO_IP, IP_PKTINFO, (const char*)&yes, sizeof(yes));
+        ok(rc == 0, "failed to set IPPROTO_IP flag IP_PKTINFO!\n");
+
         /*
          * Send a packet from the client to the server and test for specifying
          * a short control header.