schannel: Disable ALPN for Wine since it is causing problems

- Disable ALPN on Wine.

- Don't pass input secbuffer when ALPN is disabled.

When ALPN support was added a change was made to pass an input secbuffer
to initialize the context. When ALPN is enabled the buffer contains the
ALPN information, and when it's disabled the buffer is empty. In either
case this input buffer caused problems with Wine and connections would
not complete.

Bug: https://github.com/curl/curl/issues/983
Reported-by: Christian Fillion

1 files changed, 23 insertions, 11 deletions

diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c
index f991ec900..511bd11ee 100644
--- a/lib/vtls/schannel.c
+++ b/lib/vtls/schannel.c
@@ -127,6 +127,18 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
   infof(data, "schannel: SSL/TLS connection with %s port %hu (step 1/3)\n",
         conn->host.name, conn->remote_port);
 
+#ifdef HAS_ALPN
+  /* ALPN is only supported on Windows 8.1 / Server 2012 R2 and above.
+     Also it doesn't seem to be supported for Wine, see curl bug #983. */
+  connssl->use_alpn = conn->bits.tls_enable_alpn &&
+                      !GetProcAddress(GetModuleHandleA("ntdll"),
+                                      "wine_get_version") &&
+                      Curl_verify_windows_version(6, 3, PLATFORM_WINNT,
+                                                  VERSION_GREATER_THAN_EQUAL);
+#else
+  connssl->use_alpn = false;
+#endif
+
   connssl->cred = NULL;
 
   /* check for an existing re-usable credential handle */
@@ -250,10 +262,7 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
   }
 
 #ifdef HAS_ALPN
-  /* ALPN is only supported on Windows 8.1 / Server 2012 R2 and above */
-  if(conn->bits.tls_enable_alpn &&
-     Curl_verify_windows_version(6, 3, PLATFORM_WINNT,
-                                 VERSION_GREATER_THAN_EQUAL)) {
+  if(connssl->use_alpn) {
     int cur = 0;
     int list_start_index = 0;
     unsigned int* extension_len = NULL;
@@ -328,11 +337,17 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
   if(!host_name)
     return CURLE_OUT_OF_MEMORY;
 
-  /* https://msdn.microsoft.com/en-us/library/windows/desktop/aa375924.aspx */
+  /* Schannel InitializeSecurityContext:
+     https://msdn.microsoft.com/en-us/library/windows/desktop/aa375924.aspx
 
+     At the moment we don't pass inbuf unless we're using ALPN since we only
+     use it for that, and Wine (for which we currently disable ALPN) is giving
+     us problems with inbuf regardless. https://github.com/curl/curl/issues/983
+  */
   sspi_status = s_pSecFn->InitializeSecurityContext(
-    &connssl->cred->cred_handle, NULL, host_name,
-    connssl->req_flags, 0, 0, &inbuf_desc, 0, &connssl->ctxt->ctxt_handle,
+    &connssl->cred->cred_handle, NULL, host_name, connssl->req_flags, 0, 0,
+    (connssl->use_alpn ? &inbuf_desc : NULL),
+    0, &connssl->ctxt->ctxt_handle,
     &outbuf_desc, &connssl->ret_flags, &connssl->ctxt->time_stamp);
 
   Curl_unicodefree(host_name);
@@ -651,10 +666,7 @@ schannel_connect_step3(struct connectdata *conn, int sockindex)
   }
 
 #ifdef HAS_ALPN
-  /* ALPN is only supported on Windows 8.1 / Server 2012 R2 and above */
-  if(conn->bits.tls_enable_alpn &&
-     Curl_verify_windows_version(6, 3, PLATFORM_WINNT,
-                                 VERSION_GREATER_THAN_EQUAL)) {
+  if(connssl->use_alpn) {
     sspi_status = s_pSecFn->QueryContextAttributes(&connssl->ctxt->ctxt_handle,
       SECPKG_ATTR_APPLICATION_PROTOCOL, &alpn_result);