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, 121 insertions, 88 deletions

diff --git a/lib/vtls/vtls.c b/lib/vtls/vtls.c
index ed65b46b9..07d64ab9d 100644
--- a/lib/vtls/vtls.c
+++ b/lib/vtls/vtls.c
@@ -65,6 +65,7 @@
 #include "url.h"
 #include "progress.h"
 #include "share.h"
+#include "multiif.h"
 #include "timeval.h"
 #include "curl_md5.h"
 #include "warnless.h"
@@ -80,94 +81,48 @@
                                  (data->share->specifier &             \
                                   (1<<CURL_LOCK_DATA_SSL_SESSION)))
 
-static bool safe_strequal(char* str1, char* str2)
-{
-  if(str1 && str2)
-    /* both pointers point to something then compare them */
-    return (0 != strcasecompare(str1, str2)) ? TRUE : FALSE;
-  else
-    /* if both pointers are NULL then treat them as equal */
-    return (!str1 && !str2) ? TRUE : FALSE;
-}
+#define CLONE_STRING(var) if(source->var) { \
+                            dest->var = strdup(source->var); \
+                            if(!dest->var) \
+                               return FALSE; \
+                          } \
+                          else \
+                            dest->var = NULL;
 
 bool
-Curl_ssl_config_matches(struct ssl_config_data* data,
-                        struct ssl_config_data* needle)
+Curl_ssl_config_matches(struct ssl_primary_config* data,
+                        struct ssl_primary_config* needle)
 {
   if((data->version == needle->version) &&
      (data->verifypeer == needle->verifypeer) &&
      (data->verifyhost == needle->verifyhost) &&
-     safe_strequal(data->CApath, needle->CApath) &&
-     safe_strequal(data->CAfile, needle->CAfile) &&
-     safe_strequal(data->clientcert, needle->clientcert) &&
-     safe_strequal(data->cipher_list, needle->cipher_list))
+     Curl_safe_strcasecompare(data->CApath, needle->CApath) &&
+     Curl_safe_strcasecompare(data->CAfile, needle->CAfile) &&
+     Curl_safe_strcasecompare(data->clientcert, needle->clientcert) &&
+     Curl_safe_strcasecompare(data->cipher_list, needle->cipher_list))
     return TRUE;
 
   return FALSE;
 }
 
 bool
-Curl_clone_ssl_config(struct ssl_config_data *source,
-                      struct ssl_config_data *dest)
+Curl_clone_primary_ssl_config(struct ssl_primary_config *source,
+                              struct ssl_primary_config *dest)
 {
-  dest->sessionid = source->sessionid;
   dest->verifyhost = source->verifyhost;
   dest->verifypeer = source->verifypeer;
   dest->version = source->version;
 
-  if(source->CAfile) {
-    dest->CAfile = strdup(source->CAfile);
-    if(!dest->CAfile)
-      return FALSE;
-  }
-  else
-    dest->CAfile = NULL;
-
-  if(source->CApath) {
-    dest->CApath = strdup(source->CApath);
-    if(!dest->CApath)
-      return FALSE;
-  }
-  else
-    dest->CApath = NULL;
-
-  if(source->cipher_list) {
-    dest->cipher_list = strdup(source->cipher_list);
-    if(!dest->cipher_list)
-      return FALSE;
-  }
-  else
-    dest->cipher_list = NULL;
-
-  if(source->egdsocket) {
-    dest->egdsocket = strdup(source->egdsocket);
-    if(!dest->egdsocket)
-      return FALSE;
-  }
-  else
-    dest->egdsocket = NULL;
-
-  if(source->random_file) {
-    dest->random_file = strdup(source->random_file);
-    if(!dest->random_file)
-      return FALSE;
-  }
-  else
-    dest->random_file = NULL;
-
-  if(source->clientcert) {
-    dest->clientcert = strdup(source->clientcert);
-    if(!dest->clientcert)
-      return FALSE;
-    dest->sessionid = FALSE;
-  }
-  else
-    dest->clientcert = NULL;
-
+  CLONE_STRING(CAfile);
+  CLONE_STRING(CApath);
+  CLONE_STRING(cipher_list);
+  CLONE_STRING(egdsocket);
+  CLONE_STRING(random_file);
+  CLONE_STRING(clientcert);
   return TRUE;
 }
 
-void Curl_free_ssl_config(struct ssl_config_data* sslc)
+void Curl_free_primary_ssl_config(struct ssl_primary_config* sslc)
 {
   Curl_safefree(sslc->CAfile);
   Curl_safefree(sslc->CApath);
@@ -217,19 +172,41 @@ void Curl_ssl_cleanup(void)
 static bool ssl_prefs_check(struct Curl_easy *data)
 {
   /* check for CURLOPT_SSLVERSION invalid parameter value */
-  if((data->set.ssl.version < 0)
-     || (data->set.ssl.version >= CURL_SSLVERSION_LAST)) {
+  if((data->set.ssl.primary.version < 0)
+     || (data->set.ssl.primary.version >= CURL_SSLVERSION_LAST)) {
     failf(data, "Unrecognized parameter value passed via CURLOPT_SSLVERSION");
     return FALSE;
   }
   return TRUE;
 }
 
+static CURLcode
+ssl_connect_init_proxy(struct connectdata *conn, int sockindex) {
+  DEBUGASSERT(conn->bits.proxy_ssl_connected[sockindex]);
+  if(ssl_connection_complete == conn->ssl[sockindex].state &&
+     !conn->proxy_ssl[sockindex].use) {
+#if defined(USE_OPENSSL) || defined(USE_GNUTLS) || defined(USE_NSS) || \
+    defined(USE_GSKIT)
+    conn->proxy_ssl[sockindex] = conn->ssl[sockindex];
+    memset(&conn->ssl[sockindex], 0, sizeof(conn->ssl[sockindex]));
+#else
+    return CURLE_NOT_BUILT_IN;
+#endif
+  }
+  return CURLE_OK;
+}
+
 CURLcode
 Curl_ssl_connect(struct connectdata *conn, int sockindex)
 {
   CURLcode result;
 
+  if(conn->bits.proxy_ssl_connected[sockindex]) {
+    result = ssl_connect_init_proxy(conn, sockindex);
+    if(result)
+      return result;
+  }
+
   if(!ssl_prefs_check(conn->data))
     return CURLE_SSL_CONNECT_ERROR;
 
@@ -250,6 +227,11 @@ Curl_ssl_connect_nonblocking(struct connectdata *conn, int sockindex,
                              bool *done)
 {
   CURLcode result;
+  if(conn->bits.proxy_ssl_connected[sockindex]) {
+    result = ssl_connect_init_proxy(conn, sockindex);
+    if(result)
+      return result;
+  }
 
   if(!ssl_prefs_check(conn->data))
     return CURLE_SSL_CONNECT_ERROR;
@@ -292,7 +274,8 @@ 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)
 {
   struct curl_ssl_session *check;
   struct Curl_easy *data = conn->data;
@@ -300,11 +283,18 @@ bool Curl_ssl_getsessionid(struct connectdata *conn,
   long *general_age;
   bool no_match = TRUE;
 
+  const bool isProxy = CONNECT_PROXY_SSL();
+  struct ssl_primary_config * const ssl_config = isProxy ?
+                                                 &conn->proxy_ssl_config :
+                                                 &conn->ssl_config;
+  const char * const name = isProxy ? conn->http_proxy.host.name :
+                                      conn->host.name;
+  int port = isProxy ? (int)conn->port : conn->remote_port;
   *ssl_sessionid = NULL;
 
-  DEBUGASSERT(conn->ssl_config.sessionid);
+  DEBUGASSERT(data->set.general_ssl.sessionid);
 
-  if(!conn->ssl_config.sessionid)
+  if(!data->set.general_ssl.sessionid)
     /* session ID re-use is disabled */
     return TRUE;
 
@@ -314,21 +304,21 @@ bool Curl_ssl_getsessionid(struct connectdata *conn,
   else
     general_age = &data->state.sessionage;
 
-  for(i = 0; i < data->set.ssl.max_ssl_sessions; i++) {
+  for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++) {
     check = &data->state.session[i];
     if(!check->sessionid)
       /* not session ID means blank entry */
       continue;
-    if(strcasecompare(conn->host.name, check->name) &&
+    if(strcasecompare(name, check->name) &&
        ((!conn->bits.conn_to_host && !check->conn_to_host) ||
         (conn->bits.conn_to_host && check->conn_to_host &&
          strcasecompare(conn->conn_to_host.name, check->conn_to_host))) &&
        ((!conn->bits.conn_to_port && check->conn_to_port == -1) ||
         (conn->bits.conn_to_port && check->conn_to_port != -1 &&
          conn->conn_to_port == check->conn_to_port)) &&
-       (conn->remote_port == check->remote_port) &&
+       (port == check->remote_port) &&
        strcasecompare(conn->handler->scheme, check->scheme) &&
-       Curl_ssl_config_matches(&conn->ssl_config, &check->ssl_config)) {
+       Curl_ssl_config_matches(ssl_config, &check->ssl_config)) {
       /* yes, we have a session ID! */
       (*general_age)++;          /* increase general age */
       check->age = *general_age; /* set this as used in this age */
@@ -357,7 +347,7 @@ void Curl_ssl_kill_session(struct curl_ssl_session *session)
     session->sessionid = NULL;
     session->age = 0; /* fresh */
 
-    Curl_free_ssl_config(&session->ssl_config);
+    Curl_free_primary_ssl_config(&session->ssl_config);
 
     Curl_safefree(session->name);
     Curl_safefree(session->conn_to_host);
@@ -372,7 +362,7 @@ void Curl_ssl_delsessionid(struct connectdata *conn, void *ssl_sessionid)
   size_t i;
   struct Curl_easy *data=conn->data;
 
-  for(i = 0; i < data->set.ssl.max_ssl_sessions; i++) {
+  for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++) {
     struct curl_ssl_session *check = &data->state.session[i];
 
     if(check->sessionid == ssl_sessionid) {
@@ -390,7 +380,8 @@ void Curl_ssl_delsessionid(struct connectdata *conn, void *ssl_sessionid)
  */
 CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
                                void *ssl_sessionid,
-                               size_t idsize)
+                               size_t idsize,
+                               int sockindex)
 {
   size_t i;
   struct Curl_easy *data=conn->data; /* the mother of all structs */
@@ -400,10 +391,14 @@ CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
   char *clone_conn_to_host;
   int conn_to_port;
   long *general_age;
+  const bool isProxy = CONNECT_PROXY_SSL();
+  struct ssl_primary_config * const ssl_config = isProxy ?
+                                           &conn->proxy_ssl_config :
+                                           &conn->ssl_config;
 
-  DEBUGASSERT(conn->ssl_config.sessionid);
+  DEBUGASSERT(data->set.general_ssl.sessionid);
 
-  clone_host = strdup(conn->host.name);
+  clone_host = strdup(isProxy ? conn->http_proxy.host.name : conn->host.name);
   if(!clone_host)
     return CURLE_OUT_OF_MEMORY; /* bail out */
 
@@ -434,14 +429,14 @@ CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
   }
 
   /* find an empty slot for us, or find the oldest */
-  for(i = 1; (i < data->set.ssl.max_ssl_sessions) &&
+  for(i = 1; (i < data->set.general_ssl.max_ssl_sessions) &&
         data->state.session[i].sessionid; i++) {
     if(data->state.session[i].age < oldest_age) {
       oldest_age = data->state.session[i].age;
       store = &data->state.session[i];
     }
   }
-  if(i == data->set.ssl.max_ssl_sessions)
+  if(i == data->set.general_ssl.max_ssl_sessions)
     /* cache is full, we must "kill" the oldest entry! */
     Curl_ssl_kill_session(store);
   else
@@ -457,10 +452,11 @@ CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
   store->name = clone_host;               /* clone host name */
   store->conn_to_host = clone_conn_to_host; /* clone connect to host name */
   store->conn_to_port = conn_to_port; /* connect to port number */
-  store->remote_port = conn->remote_port; /* port number */
+  /* port number */
+  store->remote_port = isProxy ? (int)conn->port : conn->remote_port;
   store->scheme = conn->handler->scheme;
 
-  if(!Curl_clone_ssl_config(&conn->ssl_config, &store->ssl_config)) {
+  if(!Curl_clone_primary_ssl_config(ssl_config, &store->ssl_config)) {
     store->sessionid = NULL; /* let caller free sessionid */
     free(clone_host);
     free(clone_conn_to_host);
@@ -476,7 +472,7 @@ void Curl_ssl_close_all(struct Curl_easy *data)
   size_t i;
   /* kill the session ID cache if not shared */
   if(data->state.session && !SSLSESSION_SHARED(data)) {
-    for(i = 0; i < data->set.ssl.max_ssl_sessions; i++)
+    for(i = 0; i < data->set.general_ssl.max_ssl_sessions; i++)
       /* the single-killer function handles empty table slots */
       Curl_ssl_kill_session(&data->state.session[i]);
 
@@ -487,6 +483,43 @@ void Curl_ssl_close_all(struct Curl_easy *data)
   curlssl_close_all(data);
 }
 
+#if defined(USE_SSLEAY) || defined(USE_GNUTLS) || defined(USE_SCHANNEL) || \
+    defined(USE_DARWINSSL) || defined(USE_NSS)
+/* This function is for OpenSSL, GnuTLS, darwinssl, and schannel only. */
+int Curl_ssl_getsock(struct connectdata *conn, curl_socket_t *socks,
+                     int numsocks)
+{
+  struct ssl_connect_data *connssl = &conn->ssl[FIRSTSOCKET];
+
+  if(!numsocks)
+    return GETSOCK_BLANK;
+
+  if(connssl->connecting_state == ssl_connect_2_writing) {
+    /* write mode */
+    socks[0] = conn->sock[FIRSTSOCKET];
+    return GETSOCK_WRITESOCK(0);
+  }
+  else if(connssl->connecting_state == ssl_connect_2_reading) {
+    /* read mode */
+    socks[0] = conn->sock[FIRSTSOCKET];
+    return GETSOCK_READSOCK(0);
+  }
+
+  return GETSOCK_BLANK;
+}
+#else
+int Curl_ssl_getsock(struct connectdata *conn,
+                          curl_socket_t *socks,
+                          int numsocks)
+{
+  (void)conn;
+  (void)socks;
+  (void)numsocks;
+  return GETSOCK_BLANK;
+}
+/* USE_SSLEAY || USE_GNUTLS || USE_SCHANNEL || USE_DARWINSSL || USE_NSS */
+#endif
+
 void Curl_ssl_close(struct connectdata *conn, int sockindex)
 {
   DEBUGASSERT((sockindex <= 1) && (sockindex >= -1));
@@ -544,7 +577,7 @@ CURLcode Curl_ssl_initsessions(struct Curl_easy *data, size_t amount)
     return CURLE_OUT_OF_MEMORY;
 
   /* store the info in the SSL section */
-  data->set.ssl.max_ssl_sessions = amount;
+  data->set.general_ssl.max_ssl_sessions = amount;
   data->state.session = session;
   data->state.sessionage = 1; /* this is brand new */
   return CURLE_OK;