proxy: Support HTTPS proxy and SOCKS+HTTP(s)

* HTTPS proxies:

An HTTPS proxy receives all transactions over an SSL/TLS connection.
Once a secure connection with the proxy is established, the user agent
uses the proxy as usual, including sending CONNECT requests to instruct
the proxy to establish a [usually secure] TCP tunnel with an origin
server. HTTPS proxies protect nearly all aspects of user-proxy
communications as opposed to HTTP proxies that receive all requests
(including CONNECT requests) in vulnerable clear text.

With HTTPS proxies, it is possible to have two concurrent _nested_
SSL/TLS sessions: the "outer" one between the user agent and the proxy
and the "inner" one between the user agent and the origin server
(through the proxy). This change adds supports for such nested sessions
as well.

A secure connection with a proxy requires its own set of the usual SSL
options (their actual descriptions differ and need polishing, see TODO):

  --proxy-cacert FILE        CA certificate to verify peer against
  --proxy-capath DIR         CA directory to verify peer against
  --proxy-cert CERT[:PASSWD] Client certificate file and password
  --proxy-cert-type TYPE     Certificate file type (DER/PEM/ENG)
  --proxy-ciphers LIST       SSL ciphers to use
  --proxy-crlfile FILE       Get a CRL list in PEM format from the file
  --proxy-insecure           Allow connections to proxies with bad certs
  --proxy-key KEY            Private key file name
  --proxy-key-type TYPE      Private key file type (DER/PEM/ENG)
  --proxy-pass PASS          Pass phrase for the private key
  --proxy-ssl-allow-beast    Allow security flaw to improve interop
  --proxy-sslv2              Use SSLv2
  --proxy-sslv3              Use SSLv3
  --proxy-tlsv1              Use TLSv1
  --proxy-tlsuser USER       TLS username
  --proxy-tlspassword STRING TLS password
  --proxy-tlsauthtype STRING TLS authentication type (default SRP)

All --proxy-foo options are independent from their --foo counterparts,
except --proxy-crlfile which defaults to --crlfile and --proxy-capath
which defaults to --capath.

Curl now also supports %{proxy_ssl_verify_result} --write-out variable,
similar to the existing %{ssl_verify_result} variable.

Supported backends: OpenSSL, GnuTLS, and NSS.

* A SOCKS proxy + HTTP/HTTPS proxy combination:

If both --socks* and --proxy options are given, Curl first connects to
the SOCKS proxy and then connects (through SOCKS) to the HTTP or HTTPS
proxy.

TODO: Update documentation for the new APIs and --proxy-* options.
Look for "Added in 7.XXX" marks.

1 files changed, 45 insertions, 37 deletions

diff --git a/lib/vtls/cyassl.c b/lib/vtls/cyassl.c
index f0c0f4a07..5570760d4 100644
--- a/lib/vtls/cyassl.c
+++ b/lib/vtls/cyassl.c
@@ -149,7 +149,7 @@ cyassl_connect_step1(struct connectdata *conn,
     return CURLE_OK;
 
   /* check to see if we've been told to use an explicit SSL/TLS version */
-  switch(data->set.ssl.version) {
+  switch(SSL_CONN_CONFIG(version)) {
   case CURL_SSLVERSION_DEFAULT:
   case CURL_SSLVERSION_TLSv1:
 #if LIBCYASSL_VERSION_HEX >= 0x03003000 /* >= 3.3.0 */
@@ -208,7 +208,7 @@ cyassl_connect_step1(struct connectdata *conn,
     return CURLE_OUT_OF_MEMORY;
   }
 
-  switch(data->set.ssl.version) {
+  switch(SSL_CONN_CONFIG(version)) {
   case CURL_SSLVERSION_DEFAULT:
   case CURL_SSLVERSION_TLSv1:
 #if LIBCYASSL_VERSION_HEX > 0x03004006 /* > 3.4.6 */
@@ -231,18 +231,18 @@ cyassl_connect_step1(struct connectdata *conn,
 
 #ifndef NO_FILESYSTEM
   /* load trusted cacert */
-  if(data->set.str[STRING_SSL_CAFILE]) {
+  if(SSL_CONN_CONFIG(CAfile)) {
     if(1 != SSL_CTX_load_verify_locations(conssl->ctx,
-                                          data->set.str[STRING_SSL_CAFILE],
-                                          data->set.str[STRING_SSL_CAPATH])) {
-      if(data->set.ssl.verifypeer) {
+                                      SSL_CONN_CONFIG(CAfile),
+                                      SSL_CONN_CONFIG(CApath))) {
+      if(SSL_CONN_CONFIG(verifypeer)) {
         /* Fail if we insist on successfully verifying the server. */
         failf(data, "error setting certificate verify locations:\n"
               "  CAfile: %s\n  CApath: %s",
-              data->set.str[STRING_SSL_CAFILE]?
-              data->set.str[STRING_SSL_CAFILE]: "none",
-              data->set.str[STRING_SSL_CAPATH]?
-              data->set.str[STRING_SSL_CAPATH] : "none");
+              SSL_CONN_CONFIG(CAfile)?
+              SSL_CONN_CONFIG(CAfile): "none",
+              SSL_CONN_CONFIG(CApath)?
+              SSL_CONN_CONFIG(CApath) : "none");
         return CURLE_SSL_CACERT_BADFILE;
       }
       else {
@@ -259,25 +259,25 @@ cyassl_connect_step1(struct connectdata *conn,
     infof(data,
           "  CAfile: %s\n"
           "  CApath: %s\n",
-          data->set.str[STRING_SSL_CAFILE] ? data->set.str[STRING_SSL_CAFILE]:
+          SSL_CONN_CONFIG(CAfile) ? SSL_CONN_CONFIG(CAfile):
           "none",
-          data->set.str[STRING_SSL_CAPATH] ? data->set.str[STRING_SSL_CAPATH]:
+          SSL_CONN_CONFIG(CApath) ? SSL_CONN_CONFIG(CApath):
           "none");
   }
 
   /* Load the client certificate, and private key */
-  if(data->set.str[STRING_CERT] && data->set.str[STRING_KEY]) {
-    int file_type = do_file_type(data->set.str[STRING_CERT_TYPE]);
+  if(SSL_SET_OPTION(cert) && SSL_SET_OPTION(key)) {
+    int file_type = do_file_type(SSL_SET_OPTION(cert_type));
 
-    if(SSL_CTX_use_certificate_file(conssl->ctx, data->set.str[STRING_CERT],
+    if(SSL_CTX_use_certificate_file(conssl->ctx, SSL_SET_OPTION(cert),
                                      file_type) != 1) {
       failf(data, "unable to use client certificate (no key or wrong pass"
             " phrase?)");
       return CURLE_SSL_CONNECT_ERROR;
     }
 
-    file_type = do_file_type(data->set.str[STRING_KEY_TYPE]);
-    if(SSL_CTX_use_PrivateKey_file(conssl->ctx, data->set.str[STRING_KEY],
+    file_type = do_file_type(SSL_SET_OPTION(key_type));
+    if(SSL_CTX_use_PrivateKey_file(conssl->ctx, SSL_SET_OPTION(key),
                                     file_type) != 1) {
       failf(data, "unable to set private key");
       return CURLE_SSL_CONNECT_ERROR;
@@ -290,7 +290,8 @@ cyassl_connect_step1(struct connectdata *conn,
    * anyway. In the latter case the result of the verification is checked with
    * SSL_get_verify_result() below. */
   SSL_CTX_set_verify(conssl->ctx,
-                     data->set.ssl.verifypeer?SSL_VERIFY_PEER:SSL_VERIFY_NONE,
+                     SSL_CONN_CONFIG(verifypeer)?SSL_VERIFY_PEER:
+                                                 SSL_VERIFY_NONE,
                      NULL);
 
 #ifdef HAVE_SNI
@@ -299,13 +300,15 @@ cyassl_connect_step1(struct connectdata *conn,
 #ifdef ENABLE_IPV6
     struct in6_addr addr6;
 #endif
-    size_t hostname_len = strlen(conn->host.name);
+    const char * const hostname = SSL_IS_PROXY() ? conn->http_proxy.host.name :
+      conn->host.name;
+    size_t hostname_len = strlen(hostname);
     if((hostname_len < USHRT_MAX) &&
-       (0 == Curl_inet_pton(AF_INET, conn->host.name, &addr4)) &&
+       (0 == Curl_inet_pton(AF_INET, hostname, &addr4)) &&
 #ifdef ENABLE_IPV6
-       (0 == Curl_inet_pton(AF_INET6, conn->host.name, &addr6)) &&
+       (0 == Curl_inet_pton(AF_INET6, hostname, &addr6)) &&
 #endif
-       (CyaSSL_CTX_UseSNI(conssl->ctx, CYASSL_SNI_HOST_NAME, conn->host.name,
+       (CyaSSL_CTX_UseSNI(conssl->ctx, CYASSL_SNI_HOST_NAME, hostname,
                           (unsigned short)hostname_len) != 1)) {
       infof(data, "WARNING: failed to configure server name indication (SNI) "
             "TLS extension\n");
@@ -334,7 +337,7 @@ cyassl_connect_step1(struct connectdata *conn,
     }
   }
 #ifdef NO_FILESYSTEM
-  else if(data->set.ssl.verifypeer) {
+  else if(SSL_CONN_CONFIG(verifypeer)) {
     failf(data, "SSL: Certificates couldn't be loaded because CyaSSL was built"
           " with \"no filesystem\". Either disable peer verification"
           " (insecure) or if you are building an application with libcurl you"
@@ -380,11 +383,11 @@ cyassl_connect_step1(struct connectdata *conn,
 #endif /* HAVE_ALPN */
 
   /* Check if there's a cached ID we can/should use here! */
-  if(conn->ssl_config.sessionid) {
+  if(data->set.general_ssl.sessionid) {
     void *ssl_sessionid = NULL;
 
     Curl_ssl_sessionid_lock(conn);
-    if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
+    if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL, sockindex)) {
       /* we got a session id, use it! */
       if(!SSL_set_session(conssl->handle, ssl_sessionid)) {
         Curl_ssl_sessionid_unlock(conn);
@@ -417,13 +420,17 @@ cyassl_connect_step2(struct connectdata *conn,
   int ret = -1;
   struct Curl_easy *data = conn->data;
   struct ssl_connect_data* conssl = &conn->ssl[sockindex];
+  const char * const hostname = SSL_IS_PROXY() ? conn->http_proxy.host.name :
+    conn->host.name;
+  const char * const dispname = SSL_IS_PROXY() ?
+    conn->http_proxy.host.dispname : conn->host.dispname;
 
   conn->recv[sockindex] = cyassl_recv;
   conn->send[sockindex] = cyassl_send;
 
   /* Enable RFC2818 checks */
-  if(data->set.ssl.verifyhost) {
-    ret = CyaSSL_check_domain_name(conssl->handle, conn->host.name);
+  if(SSL_CONN_CONFIG(verifyhost)) {
+    ret = CyaSSL_check_domain_name(conssl->handle, hostname);
     if(ret == SSL_FAILURE)
       return CURLE_OUT_OF_MEMORY;
   }
@@ -447,31 +454,31 @@ cyassl_connect_step2(struct connectdata *conn,
     else if(DOMAIN_NAME_MISMATCH == detail) {
 #if 1
       failf(data, "\tsubject alt name(s) or common name do not match \"%s\"\n",
-            conn->host.dispname);
+            dispname);
       return CURLE_PEER_FAILED_VERIFICATION;
 #else
       /* When the CyaSSL_check_domain_name() is used and you desire to continue
-       * on a DOMAIN_NAME_MISMATCH, i.e. 'data->set.ssl.verifyhost == 0',
+       * on a DOMAIN_NAME_MISMATCH, i.e. 'conn->ssl_config.verifyhost == 0',
        * CyaSSL version 2.4.0 will fail with an INCOMPLETE_DATA error. The only
        * way to do this is currently to switch the CyaSSL_check_domain_name()
-       * in and out based on the 'data->set.ssl.verifyhost' value. */
-      if(data->set.ssl.verifyhost) {
+       * in and out based on the 'conn->ssl_config.verifyhost' value. */
+      if(SSL_CONN_CONFIG(verifyhost)) {
         failf(data,
               "\tsubject alt name(s) or common name do not match \"%s\"\n",
-              conn->host.dispname);
+              dispname);
         return CURLE_PEER_FAILED_VERIFICATION;
       }
       else {
         infof(data,
               "\tsubject alt name(s) and/or common name do not match \"%s\"\n",
-              conn->host.dispname);
+              dispname);
         return CURLE_OK;
       }
 #endif
     }
 #if LIBCYASSL_VERSION_HEX >= 0x02007000 /* 2.7.0 */
     else if(ASN_NO_SIGNER_E == detail) {
-      if(data->set.ssl.verifypeer) {
+      if(SSL_CONN_CONFIG(verifypeer)) {
         failf(data, "\tCA signer not available for verification\n");
         return CURLE_SSL_CACERT_BADFILE;
       }
@@ -587,7 +594,7 @@ cyassl_connect_step3(struct connectdata *conn,
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
-  if(conn->ssl_config.sessionid) {
+  if(data->set.general_ssl.sessionid) {
     bool incache;
     SSL_SESSION *our_ssl_sessionid;
     void *old_ssl_sessionid = NULL;
@@ -595,7 +602,8 @@ cyassl_connect_step3(struct connectdata *conn,
     our_ssl_sessionid = SSL_get_session(connssl->handle);
 
     Curl_ssl_sessionid_lock(conn);
-    incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL));
+    incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL,
+                                      sockindex));
     if(incache) {
       if(old_ssl_sessionid != our_ssl_sessionid) {
         infof(data, "old SSL session ID is stale, removing\n");
@@ -606,7 +614,7 @@ cyassl_connect_step3(struct connectdata *conn,
 
     if(!incache) {
       result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
-                                     0 /* unknown size */);
+                                     0 /* unknown size */, sockindex);
       if(result) {
         Curl_ssl_sessionid_unlock(conn);
         failf(data, "failed to store ssl session");