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, 22 insertions, 7 deletions

diff --git a/lib/vtls/vtls.h b/lib/vtls/vtls.h
index 69d206f52..88fdb9ab2 100644
--- a/lib/vtls/vtls.h
+++ b/lib/vtls/vtls.h
@@ -50,11 +50,24 @@
 #define ALPN_HTTP_1_1_LENGTH 8
 #define ALPN_HTTP_1_1 "http/1.1"
 
-bool Curl_ssl_config_matches(struct ssl_config_data* data,
-                             struct ssl_config_data* needle);
-bool Curl_clone_ssl_config(struct ssl_config_data* source,
-                           struct ssl_config_data* dest);
-void Curl_free_ssl_config(struct ssl_config_data* sslc);
+/* set of helper macros for the backends to access the correct fields. For the
+   proxy or for the remote host - to properly support HTTPS proxy */
+
+#define SSL_IS_PROXY() (CURLPROXY_HTTPS == conn->http_proxy.proxytype && \
+  ssl_connection_complete != conn->proxy_ssl[conn->sock[SECONDARYSOCKET] == \
+  CURL_SOCKET_BAD ? FIRSTSOCKET : SECONDARYSOCKET].state)
+#define SSL_SET_OPTION(var) (SSL_IS_PROXY() ? data->set.proxy_ssl.var : \
+                             data->set.ssl.var)
+#define SSL_CONN_CONFIG(var) (SSL_IS_PROXY() ?          \
+  conn->proxy_ssl_config.var : conn->ssl_config.var)
+
+bool Curl_ssl_config_matches(struct ssl_primary_config* data,
+                             struct ssl_primary_config* needle);
+bool Curl_clone_primary_ssl_config(struct ssl_primary_config *source,
+                                   struct ssl_primary_config *dest);
+void Curl_free_primary_ssl_config(struct ssl_primary_config* sslc);
+int Curl_ssl_getsock(struct connectdata *conn, curl_socket_t *socks,
+                     int numsocks);
 
 int Curl_ssl_backend(void);
 
@@ -114,7 +127,8 @@ void Curl_ssl_sessionid_unlock(struct connectdata *conn);
  */
 bool Curl_ssl_getsessionid(struct connectdata *conn,
                            void **ssl_sessionid,
-                           size_t *idsize); /* set 0 if unknown */
+                           size_t *idsize, /* set 0 if unknown */
+                           int sockindex);
 /* add a new session ID
  * Sessionid mutex must be locked (see Curl_ssl_sessionid_lock).
  * Caller must ensure that it has properly shared ownership of this sessionid
@@ -122,7 +136,8 @@ bool Curl_ssl_getsessionid(struct connectdata *conn,
  */
 CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
                                void *ssl_sessionid,
-                               size_t idsize);
+                               size_t idsize,
+                               int sockindex);
 /* Kill a single session ID entry in the cache
  * Sessionid mutex must be locked (see Curl_ssl_sessionid_lock).
  * This will call engine-specific curlssl_session_free function, which must