[PATCH v2 1/1] ntdll: Do not send data to port 0.

[Jason Beetham]

From: Jason Beetham

On Windows it seems sending to port 0 does nothing and does not error.
Presently sendmsg errors with EINVAL.
This works around it, by checking if it's port 0 then skipping the data.
---
 dlls/ntdll/unix/socket.c | 67 ++++++++++++++++++++++++++++++++++------
 dlls/ws2_32/tests/sock.c | 25 +++++++++++++++
 2 files changed, 83 insertions(+), 9 deletions(-)

diff --git a/dlls/ntdll/unix/socket.c b/dlls/ntdll/unix/socket.c
index ac351a17a70..93774188495 100644
--- a/dlls/ntdll/unix/socket.c
+++ b/dlls/ntdll/unix/socket.c
@@ -980,6 +980,42 @@ NTSTATUS sock_read( HANDLE handle, int fd, HANDLE event, PIO_APC_ROUTINE apc,
 }

+static int isPort0( const union unix_sockaddr *uaddr)
+{
+    switch (uaddr->addr.sa_family)
+    {
+        case AF_INET:
+        {
+            return uaddr->in.sin_port == 0;
+        }
+
+        case AF_INET6:
+        {
+            return uaddr->in6.sin6_port == 0;
+        }
+
+    #ifdef HAS_IPX
+        case AF_IPX:
+        {
+            return uaddr->ipx.sipx_port == 0;
+        }
+    #endif
+
+    #ifdef HAS_IRDA
+        case AF_IRDA:
+        {
+            return FALSE
+        }
+    #endif
+
+        case AF_UNSPEC:
+            return FALSE;
+
+        default:
+            return FALSE;
+        }
+}
+
 static NTSTATUS try_send( int fd, struct async_send_ioctl *async )
 {
     union unix_sockaddr unix_addr;
@@ -1018,17 +1054,30 @@ static NTSTATUS try_send( int fd, struct async_send_ioctl *async )
     hdr.msg_iov = async->iov + async->iov_cursor;
     hdr.msg_iovlen = async->count - async->iov_cursor;

-    while ((ret = sendmsg( fd, &hdr, async->unix_flags )) == -1)
-    {
-        if (errno == EISCONN)
-        {
-            hdr.msg_name = NULL;
-            hdr.msg_namelen = 0;
+    if(isPort0(&unix_addr)){
+        /* Some Windows applications(Spellforce 3 is known to) send to port 0.
+         * This causes 'sendmsg' to throw a EINVAL error on Windows this does nothing but consume the data.
+         * This workaround says we successfully sent data even though we didnt send anything.
+         * Matching the Windows behaviour, making the program work(in theory).
+         */
+        ret = 0;
+        for(int i = 0; i < hdr.msg_iovlen; i++){
+            ret += hdr.msg_iov[i].iov_len;
         }
-        else if (errno != EINTR)
+        WARN("Attempting to send to port 0, skipping over %zd bytes\n", ret);
+    }else{
+        while ((ret = sendmsg( fd, &hdr, async->unix_flags )) == -1)
         {
-            if (errno != EWOULDBLOCK) WARN( "sendmsg: %s\n", strerror( errno ) );
-            return sock_errno_to_status( errno );
+            if (errno == EISCONN)
+            {
+                hdr.msg_name = NULL;
+                hdr.msg_namelen = 0;
+            }
+            else if (errno != EINTR)
+            {
+                if (errno != EWOULDBLOCK) WARN( "sendmsg: %s\n", strerror( errno ) );
+                return sock_errno_to_status( errno );
+            }
         }
     }

diff --git a/dlls/ws2_32/tests/sock.c b/dlls/ws2_32/tests/sock.c
index d29e1c768dc..74b4cf1a30f 100644
--- a/dlls/ws2_32/tests/sock.c
+++ b/dlls/ws2_32/tests/sock.c
@@ -13659,6 +13659,30 @@ static void test_connect_udp(void)
     closesocket(client);
 }

+static void test_WSAsendto_port0(void)
+{
+    SOCKET s;
+    struct sockaddr_in addr;
+    char buf[12] = "hello world";
+    WSABUF data_buf;
+    DWORD bytesSent;
+    int ret;
+
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(139);
+    addr.sin_addr.s_addr = inet_addr("127.0.0.1");
+    data_buf.len = sizeof(buf);
+    data_buf.buf = buf;
+
+    s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+    ok(s != INVALID_SOCKET, "failed to create socket, error %u\n", WSAGetLastError());
+
+    ret = WSASendTo(s, &data_buf, 1, &bytesSent, 0, (struct sockaddr *)&addr, sizeof(addr), NULL, NULL);
+    ok(!ret, "failed to send data to port 0, error: %lu\n", GetLastError());
+    ok(bytesSent == sizeof(buf), "Failed to send full data to port 0, error: %lu\n", GetLastError());
+}
+
+
 START_TEST( sock )
 {
     int i;
@@ -13740,6 +13764,7 @@ START_TEST( sock )
     test_tcp_reset();
     test_icmp();
     test_connect_udp();
+    test_WSAsendto_port0();

/* this is an io heavy test, do it at the end so the kernel doesn't start dropping packets */
     test_send();