[PATCH v10 2/2] 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 | 50 ++++++++++++++++++++++++++++++++++------
 dlls/ws2_32/tests/sock.c |  4 ++--
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/dlls/ntdll/unix/socket.c b/dlls/ntdll/unix/socket.c
index ac351a17a70..0be2c9e4dd5 100644
--- a/dlls/ntdll/unix/socket.c
+++ b/dlls/ntdll/unix/socket.c
@@ -979,12 +979,28 @@ NTSTATUS sock_read( HANDLE handle, int fd, HANDLE event, PIO_APC_ROUTINE apc,
     return sock_recv( handle, event, apc, apc_user, io, fd, async, 1 );
 }

+static BOOL is_port0( 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;
+        default:
+            return FALSE;
+    }
+}

static NTSTATUS try_send( int fd, struct async_send_ioctl *async )
 {
     union unix_sockaddr unix_addr;
     struct msghdr hdr;
     ssize_t ret;
+    int protocol;
+    int opt_err;
+    socklen_t opt_len;
+

memset( &hdr, 0, sizeof(hdr) );
     if (async->addr)
@@ -1018,17 +1034,37 @@ 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)
+    opt_len = sizeof(protocol);
+    opt_err = getsockopt(fd, SOL_SOCKET, SO_TYPE, &protocol, &opt_len);
+    printf("Protocol: %d\n", protocol);
+    if (!opt_err && protocol == IPPROTO_UDP && is_port0(&unix_addr))
     {
-        if (errno == EISCONN)
+        /* 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(ssize_t i = 0; i < hdr.msg_iovlen; i++)
         {
-            hdr.msg_name = NULL;
-            hdr.msg_namelen = 0;
+            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 a388a35d1e1..ca0527ae438 100644
--- a/dlls/ws2_32/tests/sock.c
+++ b/dlls/ws2_32/tests/sock.c
@@ -13678,8 +13678,8 @@ static void test_WSASendto_port0(void)
     ok(s != INVALID_SOCKET, "failed to create socket, error %u\n", WSAGetLastError());

ret = WSASendTo(s, &data_buf, 1, &bytes_sent, 0, (struct sockaddr *)&addr, sizeof(addr), NULL, NULL);
-    todo_wine ok(!ret, "got error %u\n", WSAGetLastError());
-    todo_wine ok(bytes_sent == sizeof(buf), "Failed to send full data(%lu) only sent(%lu)\n", sizeof(buf), bytes_sent);
+    ok(!ret, "got error %u\n", WSAGetLastError());
+    ok(bytes_sent == sizeof(buf), "Failed to send full data(%lu) only sent(%lu)\n", (unsigned long) sizeof(buf), (unsigned long) bytes_sent);
     closesocket(s);
 }