preproxy: renamed what was added as SOCKS_PROXY

CURLOPT_SOCKS_PROXY -> CURLOPT_PRE_PROXY

Added the corresponding --preroxy command line option. Sets a SOCKS
proxy to connect to _before_ connecting to a HTTP(S) proxy.

12 files changed, 80 insertions, 29 deletions

diff --git a/docs/cmdline-opts/preproxy.d b/docs/cmdline-opts/preproxy.d
new file mode 100644
index 000000000..ebef4ab07
--- /dev/null
+++ b/docs/cmdline-opts/preproxy.d
@@ -0,0 +1,21 @@
+Long: preproxy
+Arg: [protocol://]host[:port]
+Help: Use this proxy first
+Added: 7.52.0
+---
+Use the specified proxy before connecting to the ordinary proxy. Hence pre
+proxy. A pre proxy must be a SOCKS speaking proxy.
+
+The pre proxy string should be specified with a protocol:// prefix to specify
+alternative proxy protocols. Use socks4://, socks4a://, socks5:// or
+socks5h:// to request the specific SOCKS version to be used. No protocol
+specified will make curl default to SOCKS4.
+
+If the port number is not specified in the proxy string, it is assumed to be
+1080.
+
+User and password that might be provided in the proxy string are URL decoded
+by curl. This allows you to pass in special characters such as @ by using %40
+or pass in a colon with %3a.
+
+If this option is used several times, the last one will be used.
diff --git a/docs/curl.1 b/docs/curl.1
index c455b897f..97166fc77 100644
--- a/docs/curl.1
+++ b/docs/curl.1
@@ -1298,6 +1298,25 @@ is used in conjunction with the user name which can be specified as part of the
 The Bearer Token and user name are formatted according to RFC 6750.
 
 If this option is used several times, the last one will be used.
+.IP "--preproxy [protocol://]host[:port]"
+Use the specified proxy before connecting to the ordinary proxy. Hence pre
+proxy. A pre proxy must be a SOCKS speaking proxy.
+
+The pre proxy string should be specified with a protocol:// prefix to specify
+alternative proxy protocols. Use socks4://, socks4a://, socks5:// or
+socks5h:// to request the specific SOCKS version to be used. No protocol
+specified will make curl default to SOCKS4.
+
+If the port number is not specified in the proxy string, it is assumed to be
+1080.
+
+User and password that might be provided in the proxy string are URL decoded
+by curl. This allows you to pass in special characters such as @ by using %40
+or pass in a colon with %3a.
+
+If this option is used several times, the last one will be used.
+
+Added in 7.52.0.
 .IP "--proxy-header <header>"
 (HTTP) Extra header to include in the request when sending HTTP to a
 proxy. You may specify any number of extra headers. This is the equivalent
diff --git a/docs/libcurl/opts/CURLOPT_SOCKS_PROXY.3 b/docs/libcurl/opts/CURLOPT_PRE_PROXY.3
index d3e6905bf..035dd3ac6 100644
--- a/docs/libcurl/opts/CURLOPT_SOCKS_PROXY.3
+++ b/docs/libcurl/opts/CURLOPT_PRE_PROXY.3
@@ -20,15 +20,15 @@
 .\" *
 .\" **************************************************************************
 .\"
-.TH CURLOPT_SOCKS_PROXY 3 "16 Nov 2016" "libcurl 7.52.0" "curl_easy_setopt options"
+.TH CURLOPT_PRE_PROXY 3 "16 Nov 2016" "libcurl 7.52.0" "curl_easy_setopt options"
 .SH NAME
-CURLOPT_SOCKS_PROXY \- set SOCKS proxy to use
+CURLOPT_PRE_PROXY \- set pre-proxy to use
 .SH SYNOPSIS
 #include <curl/curl.h>
 
-CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKS_PROXY, char *proxy);
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);
 .SH DESCRIPTION
-Set the SOCKS \fIproxy\fP to use for the upcoming request. The parameter
+Set the \fIpreproxy\fP to use for the upcoming request. The parameter
 should be a char * to a zero terminated string holding the host name or dotted
 numerical IP address. A numerical IPv6 address must be written within
 [brackets].
@@ -38,16 +38,20 @@ name. The proxy's port number may optionally be specified with the separate
 option \fICURLOPT_PROXYPORT(3)\fP. If not specified, libcurl will default to
 using port 1080 for proxies.
 
-The proxy string may be prefixed with [scheme]:// to specify which kind of
-proxy is used. Use socks4://, socks4a://, socks5:// or socks5h:// (the last
+A pre proxy is a SOCKS proxy that curl connects to before it connects to the
+HTTP(S) proxy specified in the \fICURLOPT_PROXY\fP option. The pre proxy can
+only be a SOCKS proxy.
+
+The pre proxy string should be prefixed with [scheme]:// to specify which kind
+of socks is used. Use socks4://, socks4a://, socks5:// or socks5h:// (the last
 one to enable socks5 and asking the proxy to do the resolving, also known as
 \fICURLPROXY_SOCKS5_HOSTNAME\fP type) to request the specific SOCKS version to
 be used. Otherwise SOCKS4 is used as default.
 
-Setting the proxy string to "" (an empty string) will explicitly disable the
-use of a proxy, even if there is an environment variable set for it.
+Setting the pre proxy string to "" (an empty string) will explicitly disable
+the use of a pre proxy.
 .SH DEFAULT
-Default is NULL, meaning no socks proxy is used.
+Default is NULL, meaning no pre proxy is used.
 
 When you set a host name to use, do not assume that there's any particular
 single port number used widely for proxies. Specify it!
diff --git a/docs/libcurl/opts/Makefile.am b/docs/libcurl/opts/Makefile.am
index 9a9cba1d8..eb7ca1bb5 100644
--- a/docs/libcurl/opts/Makefile.am
+++ b/docs/libcurl/opts/Makefile.am
@@ -212,6 +212,7 @@ man_MANS =                                      \
  CURLOPT_POSTQUOTE.3                            \
  CURLOPT_POSTREDIR.3                            \
  CURLOPT_PREQUOTE.3                             \
+ CURLOPT_PRE_PROXY.3                            \
  CURLOPT_PRIVATE.3                              \
  CURLOPT_PROGRESSDATA.3                         \
  CURLOPT_PROGRESSFUNCTION.3                     \
@@ -269,7 +270,6 @@ man_MANS =                                      \
  CURLOPT_SOCKOPTFUNCTION.3                      \
  CURLOPT_SOCKS5_GSSAPI_NEC.3                    \
  CURLOPT_SOCKS5_GSSAPI_SERVICE.3                \
- CURLOPT_SOCKS_PROXY.3                          \
  CURLOPT_SSH_AUTH_TYPES.3                       \
  CURLOPT_SSH_HOST_PUBLIC_KEY_MD5.3              \
  CURLOPT_SSH_KEYDATA.3                          \
@@ -522,6 +522,7 @@ HTMLPAGES =                                     \
  CURLOPT_POSTQUOTE.html                         \
  CURLOPT_POSTREDIR.html                         \
  CURLOPT_PREQUOTE.html                          \
+ CURLOPT_PRE_PROXY.html                         \
  CURLOPT_PRIVATE.html                           \
  CURLOPT_PROGRESSDATA.html                      \
  CURLOPT_PROGRESSFUNCTION.html                  \
@@ -579,7 +580,6 @@ HTMLPAGES =                                     \
  CURLOPT_SOCKOPTFUNCTION.html                   \
  CURLOPT_SOCKS5_GSSAPI_NEC.html                 \
  CURLOPT_SOCKS5_GSSAPI_SERVICE.html             \
- CURLOPT_SOCKS_PROXY.html                       \
  CURLOPT_SSH_AUTH_TYPES.html                    \
  CURLOPT_SSH_HOST_PUBLIC_KEY_MD5.html           \
  CURLOPT_SSH_KEYDATA.html                       \
@@ -832,6 +832,7 @@ PDFPAGES =                                      \
  CURLOPT_POSTQUOTE.pdf                          \
  CURLOPT_POSTREDIR.pdf                          \
  CURLOPT_PREQUOTE.pdf                           \
+ CURLOPT_PRE_PROXY.pdf                          \
  CURLOPT_PRIVATE.pdf                            \
  CURLOPT_PROGRESSDATA.pdf                       \
  CURLOPT_PROGRESSFUNCTION.pdf                   \
@@ -889,7 +890,6 @@ PDFPAGES =                                      \
  CURLOPT_SOCKOPTFUNCTION.pdf                    \
  CURLOPT_SOCKS5_GSSAPI_NEC.pdf                  \
  CURLOPT_SOCKS5_GSSAPI_SERVICE.pdf              \
- CURLOPT_SOCKS_PROXY.pdf                        \
  CURLOPT_SSH_AUTH_TYPES.pdf                     \
  CURLOPT_SSH_HOST_PUBLIC_KEY_MD5.pdf            \
  CURLOPT_SSH_KEYDATA.pdf                        \
diff --git a/include/curl/curl.h b/include/curl/curl.h
index f5dd65d49..5b4ae469e 100644
--- a/include/curl/curl.h
+++ b/include/curl/curl.h
@@ -1763,8 +1763,8 @@ typedef enum {
      CURLSSLOPT_* */
   CINIT(PROXY_SSL_OPTIONS, LONG, 261),
 
-  /* Name of socks proxy to use. */
-  CINIT(SOCKS_PROXY, STRINGPOINT, 262),
+  /* Name of pre proxy to use. */
+  CINIT(PRE_PROXY, STRINGPOINT, 262),
 
   /* The public key in DER form used to validate the proxy public key
      this option is used only if PROXY_SSL_VERIFYPEER is true */
diff --git a/lib/url.c b/lib/url.c
index f975b0d69..7944d7b0c 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1472,14 +1472,14 @@ CURLcode Curl_setopt(struct Curl_easy *data, CURLoption option,
                        va_arg(param, char *));
     break;
 
-  case CURLOPT_SOCKS_PROXY:
+  case CURLOPT_PRE_PROXY:
     /*
      * Set proxy server:port to use as SOCKS proxy.
      *
      * If the proxy is set to "" or NULL we explicitly say that we don't want
      * to use the socks proxy.
      */
-    result = setstropt(&data->set.str[STRING_SOCKS_PROXY],
+    result = setstropt(&data->set.str[STRING_PRE_PROXY],
                        va_arg(param, char *));
     break;
 
@@ -4126,7 +4126,7 @@ static struct connectdata *allocate_conn(struct Curl_easy *data)
   conn->bits.socksproxy = (conn->bits.proxy &&
                            !conn->bits.httpproxy) ? TRUE : FALSE;
 
-  if(data->set.str[STRING_SOCKS_PROXY] && *data->set.str[STRING_SOCKS_PROXY]) {
+  if(data->set.str[STRING_PRE_PROXY] && *data->set.str[STRING_PRE_PROXY]) {
     conn->bits.proxy = TRUE;
     conn->bits.socksproxy = TRUE;
   }
@@ -6184,8 +6184,8 @@ static CURLcode create_conn(struct Curl_easy *data,
     }
   }
 
-  if(data->set.str[STRING_SOCKS_PROXY]) {
-    socksproxy = strdup(data->set.str[STRING_SOCKS_PROXY]);
+  if(data->set.str[STRING_PRE_PROXY]) {
+    socksproxy = strdup(data->set.str[STRING_PRE_PROXY]);
     /* if global socks proxy is set, this is it */
     if(NULL == socksproxy) {
       failf(data, "memory shortage");
diff --git a/lib/urldata.h b/lib/urldata.h
index 595e797b7..0271d266b 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1468,7 +1468,7 @@ enum dupstring {
   STRING_NETRC_FILE,      /* if not NULL, use this instead of trying to find
                              $HOME/.netrc */
   STRING_PROXY,           /* proxy to use */
-  STRING_SOCKS_PROXY,     /* socks proxy to use */
+  STRING_PRE_PROXY,       /* pre socks proxy to use */
   STRING_SET_RANGE,       /* range, if used */
   STRING_SET_REFERER,     /* custom string for the HTTP referer field */
   STRING_SET_URL,         /* what original URL to work on */
diff --git a/src/tool_cfgable.c b/src/tool_cfgable.c
index 5d38fb338..f00a0d1e7 100644
--- a/src/tool_cfgable.c
+++ b/src/tool_cfgable.c
@@ -150,7 +150,7 @@ static void free_config_fields(struct OperationConfig *config)
   curl_slist_free_all(config->resolve);
   curl_slist_free_all(config->connect_to);
 
-  Curl_safefree(config->socksproxy);
+  Curl_safefree(config->preproxy);
   Curl_safefree(config->proxy_service_name);
   Curl_safefree(config->service_name);
 
diff --git a/src/tool_cfgable.h b/src/tool_cfgable.h
index 30749ffff..5db86f4e3 100644
--- a/src/tool_cfgable.h
+++ b/src/tool_cfgable.h
@@ -178,9 +178,7 @@ struct OperationConfig {
   bool ftp_ssl_control;
   bool ftp_ssl_ccc;
   int ftp_ssl_ccc_mode;
-
-  char *socksproxy;         /* set to server string */
-
+  char *preproxy;
   int socks5_gssapi_nec;    /* The NEC reference server does not protect the
                                encryption type exchange */
   char *proxy_service_name; /* set authentication service name for HTTP and
diff --git a/src/tool_getparam.c b/src/tool_getparam.c
index f94a2b629..16d58489f 100644
--- a/src/tool_getparam.c
+++ b/src/tool_getparam.c
@@ -290,6 +290,7 @@ static const struct LongShort aliases[]= {
   {"V",  "version",                  FALSE},
   {"w",  "write-out",                TRUE},
   {"x",  "proxy",                    TRUE},
+  {"xa", "preproxy",                 TRUE},
   {"X",  "request",                  TRUE},
   {"Y",  "speed-limit",              TRUE},
   {"y",  "speed-time",               TRUE},
@@ -1920,9 +1921,16 @@ ParameterError getparameter(char *flag,    /* f or -long-flag */
         GetStr(&config->writeout, nextarg);
       break;
     case 'x':
-      /* proxy */
-      GetStr(&config->proxy, nextarg);
-      config->proxyver = CURLPROXY_HTTP;
+      switch(subletter) {
+      case 'a': /* --preproxy */
+        GetStr(&config->preproxy, nextarg);
+        break;
+      default:
+        /* --proxy */
+        GetStr(&config->proxy, nextarg);
+        config->proxyver = CURLPROXY_HTTP;
+        break;
+      }
       break;
     case 'X':
       /* set custom request */
diff --git a/src/tool_help.c b/src/tool_help.c
index 978d8b601..a21a336d9 100644
--- a/src/tool_help.c
+++ b/src/tool_help.c
@@ -168,6 +168,7 @@ static const char *const helptext[] = {
   "Do not switch to GET after following a 302 redirect (H)",
   "     --post303       "
   "Do not switch to GET after following a 303 redirect (H)",
+  "     --preproxy [PROTOCOL://]HOST[:PORT] Proxy before HTTP(S) proxy",
   " -#, --progress-bar  Display transfer progress as a progress bar",
   "     --proto PROTOCOLS  Enable/disable PROTOCOLS",
   "     --proto-default PROTOCOL  Use PROTOCOL for any URL missing a scheme",
diff --git a/src/tool_operate.c b/src/tool_operate.c
index 9fc03b43b..54a11f653 100644
--- a/src/tool_operate.c
+++ b/src/tool_operate.c
@@ -868,8 +868,8 @@ static CURLcode operate_do(struct GlobalConfig *global,
           my_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, config->proxytunnel?1L:0L);
 
           /* new in libcurl 7.52.0 */
-          if(config->socksproxy)
-            my_setopt_str(curl, CURLOPT_SOCKS_PROXY, config->socksproxy);
+          if(config->preproxy)
+            my_setopt_str(curl, CURLOPT_PRE_PROXY, config->preproxy);
 
           /* new in libcurl 7.10.6 */
           if(config->proxyanyauth)