CURLOPT_PROXYHEADER: set headers for proxy-only

Includes docs and new test cases: 1525, 1526 and 1527

Co-written-by: Vijay Panghal

2 files changed, 28 insertions, 0 deletions

diff --git a/docs/libcurl/curl_easy_setopt.3 b/docs/libcurl/curl_easy_setopt.3
index 5422bca8f..bda293576 100644
--- a/docs/libcurl/curl_easy_setopt.3
+++ b/docs/libcurl/curl_easy_setopt.3
@@ -1541,6 +1541,33 @@ Pass a NULL to this to reset back to no custom headers.
 
 The most commonly replaced headers have "shortcuts" in the options
 \fICURLOPT_COOKIE\fP, \fICURLOPT_USERAGENT\fP and \fICURLOPT_REFERER\fP.
+
+Starting in 7.36.0, libcurl offers an alternative option that sets or replaces
+headers only for requests that are sent to a proxy:
+\fICURLOPT_PROXYHEADER\fP. If \fICURLOPT_PROXYHEADER\fP is not used at all by
+an application, the \fICURLOPT_HTTPHEADER headers\fP will be used for proxy
+requests as well!
+.IP CURLOPT_PROXYHEADER
+Pass a pointer to a linked list of HTTP headers to pass in your HTTP request
+sent to a proxy. The rules for this list is identical to the
+\fICURLOPT_HTTPHEADER\fP option's.
+
+The headers set with this option is only ever used in requests sent to a
+proxy.
+
+As a special quirk to stay backwards compatible with the libcurl versions
+released before this option existed, all headers set with
+\fICURLOPT_HTTPHEADER\fP will also be used for proxies unless you set one or
+more headers (or even just NULL) with \fICURLOPT_PROXYHEADER\fP.
+
+The first line in a request (containing the method, usually a GET or POST) is
+not a header and cannot be replaced using this option. Only the lines
+following the request-line are headers. Adding this method line in this list
+of headers will only cause your request to send an invalid header.
+
+Pass a NULL to this to reset back to no custom headers.
+
+This option was added in libcurl 7.36.0.
 .IP CURLOPT_HTTP200ALIASES
 Pass a pointer to a linked list of aliases to be treated as valid HTTP 200
 responses.  Some servers respond with a custom header response line.  For
diff --git a/docs/libcurl/symbols-in-versions b/docs/libcurl/symbols-in-versions
index 2e9fc4da0..925e47923 100644
--- a/docs/libcurl/symbols-in-versions
+++ b/docs/libcurl/symbols-in-versions
@@ -439,6 +439,7 @@ CURLOPT_PROGRESSFUNCTION        7.1           7.32.0
 CURLOPT_PROTOCOLS               7.19.4
 CURLOPT_PROXY                   7.1
 CURLOPT_PROXYAUTH               7.10.7
+CURLOPT_PROXYHEADER             7.36.0
 CURLOPT_PROXYPASSWORD           7.19.1
 CURLOPT_PROXYPORT               7.1
 CURLOPT_PROXYTYPE               7.10