schannel: support selecting ciphers

Given the contstraints of SChannel, I'm exposing these as the algorithms
themselves instead; while replicating the ciphersuite as specified by
OpenSSL would have been preferable, I found no way in the SChannel API
to do so.

To use this from the commandline, you need to pass the names of contants
defining the desired algorithms. For example, curl --ciphers
"CALG_SHA1:CALG_RSA_SIGN:CALG_RSA_KEYX:CALG_AES_128:CALG_DH_EPHEM"
https://github.com The specific names come from wincrypt.h

Closes #2630

2 files changed, 172 insertions, 0 deletions

diff --git a/docs/CIPHERS.md b/docs/CIPHERS.md
index 99d9f7dc7..2a1d8ca7e 100644
--- a/docs/CIPHERS.md
+++ b/docs/CIPHERS.md
@@ -434,3 +434,54 @@ but libcurl maps them to the following case-insensitive names.
 `ECDHE-PSK-CHACHA20-POLY1305`,
 `DHE-PSK-CHACHA20-POLY1305`,
 `EDH-RSA-DES-CBC3-SHA`,
+
+## WinSSL
+
+WinSSL allows the enabling and disabling of encryption algorithms, but not specific ciphersuites. They are defined by Microsoft (https://msdn.microsoft.com/en-us/library/windows/desktop/aa375549(v=vs.85).aspx)
+
+`CALG_MD2`,
+`CALG_MD4`,
+`CALG_MD5`,
+`CALG_SHA`,
+`CALG_SHA1`,
+`CALG_MAC`,
+`CALG_RSA_SIGN`,
+`CALG_DSS_SIGN`,
+`CALG_NO_SIGN`,
+`CALG_RSA_KEYX`,
+`CALG_DES`,
+`CALG_3DES_112`,
+`CALG_3DES`,
+`CALG_DESX`,
+`CALG_RC2`,
+`CALG_RC4`,
+`CALG_SEAL`,
+`CALG_DH_SF`,
+`CALG_DH_EPHEM`,
+`CALG_AGREEDKEY_ANY`,
+`CALG_HUGHES_MD5`,
+`CALG_SKIPJACK`,
+`CALG_TEK`,
+`CALG_CYLINK_MEK`,
+`CALG_SSL3_SHAMD5`,
+`CALG_SSL3_MASTER`,
+`CALG_SCHANNEL_MASTER_HASH`,
+`CALG_SCHANNEL_MAC_KEY`,
+`CALG_SCHANNEL_ENC_KEY`,
+`CALG_PCT1_MASTER`,
+`CALG_SSL2_MASTER`,
+`CALG_TLS1_MASTER`,
+`CALG_RC5`,
+`CALG_HMAC`,
+`CALG_TLS1PRF`,
+`CALG_HASH_REPLACE_OWF`,
+`CALG_AES_128`,
+`CALG_AES_192`,
+`CALG_AES_256`,
+`CALG_AES`,
+`CALG_SHA_256`,
+`CALG_SHA_384`,
+`CALG_SHA_512`,
+`CALG_ECDH`,
+`CALG_ECMQV`,
+`CALG_ECDSA`,
diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c
index c50fd223a..0d69a40de 100644
--- a/lib/vtls/schannel.c
+++ b/lib/vtls/schannel.c
@@ -205,6 +205,118 @@ set_ssl_version_min_max(SCHANNEL_CRED *schannel_cred, struct connectdata *conn)
   return CURLE_OK;
 }
 
+/*longest is 26, buffer is slightly bigger*/
+#define LONGEST_ALG_ID 32
+#define CIPHEROPTION(X) \
+if(strcmp(#X, tmp) == 0) \
+  return X
+
+static int
+get_alg_id_by_name(char *name)
+{
+  char tmp[LONGEST_ALG_ID] = { 0 };
+  char *nameEnd = strchr(name, ':');
+  size_t n = nameEnd ? min(nameEnd - name, LONGEST_ALG_ID - 1) : \
+    min(strlen(name), LONGEST_ALG_ID - 1);
+  strncpy(tmp, name, n);
+  tmp[n] = 0;
+  CIPHEROPTION(CALG_MD2);
+  CIPHEROPTION(CALG_MD4);
+  CIPHEROPTION(CALG_MD5);
+  CIPHEROPTION(CALG_SHA);
+  CIPHEROPTION(CALG_SHA1);
+  CIPHEROPTION(CALG_MAC);
+  CIPHEROPTION(CALG_RSA_SIGN);
+  CIPHEROPTION(CALG_DSS_SIGN);
+/*ifdefs for the options that are defined conditionally in wincrypt.h*/
+#ifdef CALG_NO_SIGN
+  CIPHEROPTION(CALG_NO_SIGN);
+#endif
+  CIPHEROPTION(CALG_RSA_KEYX);
+  CIPHEROPTION(CALG_DES);
+  CIPHEROPTION(CALG_3DES_112);
+  CIPHEROPTION(CALG_3DES);
+  CIPHEROPTION(CALG_DESX);
+  CIPHEROPTION(CALG_RC2);
+  CIPHEROPTION(CALG_RC4);
+  CIPHEROPTION(CALG_SEAL);
+  CIPHEROPTION(CALG_DH_SF);
+  CIPHEROPTION(CALG_DH_EPHEM);
+  CIPHEROPTION(CALG_AGREEDKEY_ANY);
+  CIPHEROPTION(CALG_HUGHES_MD5);
+  CIPHEROPTION(CALG_SKIPJACK);
+  CIPHEROPTION(CALG_TEK);
+  CIPHEROPTION(CALG_CYLINK_MEK);
+  CIPHEROPTION(CALG_SSL3_SHAMD5);
+  CIPHEROPTION(CALG_SSL3_MASTER);
+  CIPHEROPTION(CALG_SCHANNEL_MASTER_HASH);
+  CIPHEROPTION(CALG_SCHANNEL_MAC_KEY);
+  CIPHEROPTION(CALG_SCHANNEL_ENC_KEY);
+  CIPHEROPTION(CALG_PCT1_MASTER);
+  CIPHEROPTION(CALG_SSL2_MASTER);
+  CIPHEROPTION(CALG_TLS1_MASTER);
+  CIPHEROPTION(CALG_RC5);
+  CIPHEROPTION(CALG_HMAC);
+  CIPHEROPTION(CALG_TLS1PRF);
+#ifdef CALG_HASH_REPLACE_OWF
+  CIPHEROPTION(CALG_HASH_REPLACE_OWF);
+#endif
+#ifdef CALG_AES_128
+  CIPHEROPTION(CALG_AES_128);
+#endif
+#ifdef CALG_AES_192
+  CIPHEROPTION(CALG_AES_192);
+#endif
+#ifdef CALG_AES_256
+  CIPHEROPTION(CALG_AES_256);
+#endif
+#ifdef CALG_AES
+  CIPHEROPTION(CALG_AES);
+#endif
+#ifdef CALG_SHA_256
+  CIPHEROPTION(CALG_SHA_256);
+#endif
+#ifdef CALG_SHA_384
+  CIPHEROPTION(CALG_SHA_384);
+#endif
+#ifdef CALG_SHA_512
+  CIPHEROPTION(CALG_SHA_512);
+#endif
+#ifdef CALG_ECDH
+  CIPHEROPTION(CALG_ECDH);
+#endif
+#ifdef CALG_ECMQV
+  CIPHEROPTION(CALG_ECMQV);
+#endif
+#ifdef CALG_ECDSA
+  CIPHEROPTION(CALG_ECDSA);
+#endif
+  return 0;
+}
+
+static CURLcode
+set_ssl_ciphers(SCHANNEL_CRED *schannel_cred, char *ciphers)
+{
+  char *startCur = ciphers;
+  int algCount = 0;
+  static ALG_ID algIds[45]; /*There are 45 listed in the MS headers*/
+  while(startCur && (0 != *startCur) && (algCount < 45)) {
+    long alg = strtol(startCur, 0, 0);
+    if(!alg)
+      alg = get_alg_id_by_name(startCur);
+    if(alg)
+      algIds[algCount++] = alg;
+    else
+      return CURLE_SSL_CIPHER;
+    startCur = strchr(startCur, ':');
+    if(startCur)
+      startCur++;
+  }
+    schannel_cred->palgSupportedAlgs = algIds;
+  schannel_cred->cSupportedAlgs = algCount;
+  return CURLE_OK;
+}
+
 #ifdef HAS_CLIENT_CERT_PATH
 static CURLcode
 get_cert_location(TCHAR *path, DWORD *store_name, TCHAR **store_path,
@@ -422,6 +534,15 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
       return CURLE_SSL_CONNECT_ERROR;
     }
 
+    if(SSL_CONN_CONFIG(cipher_list)) {
+      result = set_ssl_ciphers(&schannel_cred, SSL_CONN_CONFIG(cipher_list));
+      if(CURLE_OK != result) {
+        failf(data, "Unable to set ciphers to passed via SSL_CONN_CONFIG");
+        return result;
+      }
+    }
+
+
 #ifdef HAS_CLIENT_CERT_PATH
     /* client certificate */
     if(data->set.ssl.cert) {