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.

4 files changed, 56 insertions, 12 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                        \