schannel: add support for CURLOPT_CAINFO

- Move verify_certificate functionality in schannel.c into a new
  file called schannel_verify.c. Additionally, some structure defintions
  from schannel.c have been moved to schannel.h to allow them to be
  used in schannel_verify.c.

- Make verify_certificate functionality for Schannel available on
  all versions of Windows instead of just Windows CE. verify_certificate
  will be invoked on Windows CE or when the user specifies
  CURLOPT_CAINFO and CURLOPT_SSL_VERIFYPEER.

- In verify_certificate, create a custom certificate chain engine that
  exclusively trusts the certificate store backed by the CURLOPT_CAINFO
  file.

- doc updates of --cacert/CAINFO support for schannel

- Use CERT_NAME_SEARCH_ALL_NAMES_FLAG when invoking CertGetNameString
  when available. This implements a TODO in schannel.c to improve
  handling of multiple SANs in a certificate. In particular, all SANs
  will now be searched instead of just the first name.

- Update tool_operate.c to not search for the curl-ca-bundle.crt file
  when using Schannel to maintain backward compatibility. Previously,
  any curl-ca-bundle.crt file found in that search would have been
  ignored by Schannel. But, with CAINFO support, the file found by
  that search would have been used as the certificate store and
  could cause issues for any users that have curl-ca-bundle.crt in
  the search path.

- Update url.c to not set the build time CURL_CA_BUNDLE if the selected
  SSL backend is Schannel. We allow setting CA location for schannel
  only when explicitly specified by the user via CURLOPT_CAINFO /
  --cacert.

- Add new test cases 3000 and 3001. These test cases check that the first
  and last SAN, respectively, matches the connection hostname. New test
  certificates have been added for these cases. For 3000, the certificate
  prefix is Server-localhost-firstSAN and for 3001, the certificate
  prefix is Server-localhost-secondSAN.

- Remove TODO 15.2 (Add support for custom server certificate
  validation), this commit addresses it.

Closes https://github.com/curl/curl/pull/1325

1 files changed, 40 insertions, 0 deletions

diff --git a/lib/vtls/schannel.h b/lib/vtls/schannel.h
index 932103da4..447690027 100644
--- a/lib/vtls/schannel.h
+++ b/lib/vtls/schannel.h
@@ -26,9 +26,49 @@
 
 #ifdef USE_SCHANNEL
 
+#include <schnlsp.h>
+#include <schannel.h>
+#include "curl_sspi.h"
+
 #include "urldata.h"
 
 extern const struct Curl_ssl Curl_ssl_schannel;
 
+CURLcode verify_certificate(struct connectdata *conn, int sockindex);
+
+/* structs to expose only in schannel.c and schannel_verify.c */
+#ifdef EXPOSE_SCHANNEL_INTERNAL_STRUCTS
+struct curl_schannel_cred {
+  CredHandle cred_handle;
+  TimeStamp time_stamp;
+  int refcount;
+};
+
+struct curl_schannel_ctxt {
+  CtxtHandle ctxt_handle;
+  TimeStamp time_stamp;
+};
+
+struct ssl_backend_data {
+  struct curl_schannel_cred *cred;
+  struct curl_schannel_ctxt *ctxt;
+  SecPkgContext_StreamSizes stream_sizes;
+  size_t encdata_length, decdata_length;
+  size_t encdata_offset, decdata_offset;
+  unsigned char *encdata_buffer, *decdata_buffer;
+  /* encdata_is_incomplete: if encdata contains only a partial record that
+     can't be decrypted without another Curl_read_plain (that is, status is
+     SEC_E_INCOMPLETE_MESSAGE) then set this true. after Curl_read_plain writes
+     more bytes into encdata then set this back to false. */
+  bool encdata_is_incomplete;
+  unsigned long req_flags, ret_flags;
+  CURLcode recv_unrecoverable_err; /* schannel_recv had an unrecoverable err */
+  bool recv_sspi_close_notify; /* true if connection closed by close_notify */
+  bool recv_connection_closed; /* true if connection closed, regardless how */
+  bool use_alpn; /* true if ALPN is used for this connection */
+  bool use_manual_cred_validation; /* true if manual cred validation is used */
+};
+#endif /* EXPOSE_SCHANNEL_INTERNAL_STRUCTS */
+
 #endif /* USE_SCHANNEL */
 #endif /* HEADER_CURL_SCHANNEL_H */