[PATCH 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 | 68 ++++++++++++++++++++++++++++++++++------
 1 file changed, 59 insertions(+), 9 deletions(-)

diff --git a/dlls/ntdll/unix/socket.c b/dlls/ntdll/unix/socket.c
index ac351a17a70..b4fceb95c05 100644
--- a/dlls/ntdll/unix/socket.c
+++ b/dlls/ntdll/unix/socket.c
@@ -980,6 +980,43 @@ 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:
+        FIXME( "unknown address family %d\n", uaddr->addr.sa_family );
+        return FALSE;
+    }
+}
+
 static NTSTATUS try_send( int fd, struct async_send_ioctl *async )
 {
     union unix_sockaddr unix_addr;
@@ -1018,17 +1055,30 @@ 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 %d 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 );
+            }
         }
     }