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Implement custom HTTP header for http-proxy, and always send user-agent:
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There are some patched OpenVPN versions out there without source code
(e.g. NDMVPN) that support adding custom http header.

This patch adds custom header to OpenVPN and supports the syntax that the
"in the wild" variants use.

Patch v3 also prints all custom headers with other http options in --verb 5
Patch v4 does clean up the add_proxy_header function
Acked-by: Gert Doering <[email protected]>
Message-Id: <[email protected]>
URL: http://article.gmane.org/gmane.network.openvpn.devel/7946

Signed-off-by: Gert Doering <[email protected]>
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@schwabe @cron2
schwabe authored and cron2 committed Nov 15, 2013
1 parent 7fc9245 commit d0cb816
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Showing 4 changed files with 118 additions and 21 deletions.
7 changes: 7 additions & 0 deletions doc/openvpn.8
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Original file line number Diff line number Diff line change
Expand Up @@ -552,6 +552,13 @@ Set HTTP version number to
.B AGENT user-agent \-\-
Set HTTP "User-Agent" string to
.B user-agent.

.B CUSTOM\-HEADER name content \-\-
Adds the custom Header with
.B name
as name and
.B content
as the content of the custom HTTP header.
.\"*********************************************************
.TP
.B \-\-socks-proxy server [port]
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37 changes: 37 additions & 0 deletions src/openvpn/options.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1295,6 +1295,7 @@ option_iroute_ipv6 (struct options *o,
static void
show_http_proxy_options (const struct http_proxy_options *o)
{
int i;
msg (D_SHOW_PARMS, "BEGIN http_proxy");
SHOW_STR (server);
SHOW_INT (port);
Expand All @@ -1304,6 +1305,15 @@ show_http_proxy_options (const struct http_proxy_options *o)
SHOW_INT (timeout);
SHOW_STR (http_version);
SHOW_STR (user_agent);
for (i=0; i < MAX_CUSTOM_HTTP_HEADER && o->custom_headers[i].name;i++)
{
if (o->custom_headers[i].content)
msg (D_SHOW_PARMS, " custom_header[%d] = %s: %s", i,
o->custom_headers[i].name, o->custom_headers[i].content);
else
msg (D_SHOW_PARMS, " custom_header[%d] = %s", i,
o->custom_headers[i].name);
}
msg (D_SHOW_PARMS, "END http_proxy");
}
#endif
Expand Down Expand Up @@ -5061,6 +5071,33 @@ add_option (struct options *options,
{
ho->user_agent = p[2];
}
else if ((streq (p[1], "EXT1") || streq(p[1], "EXT2") || streq(p[1], "CUSTOM-HEADER"))
&& p[2])
{
/* In the wild patched versions use both EXT1/2 and CUSTOM-HEADER
* with either two argument or one */

struct http_custom_header *custom_header = NULL;
int i;
/* Find the first free header */
for (i=0; i < MAX_CUSTOM_HTTP_HEADER; i++) {
if (!ho->custom_headers[i].name) {
custom_header = &ho->custom_headers[i];
break;
}
}
if (!custom_header)
{
msg (msglevel, "Cannot use more than %d http-proxy-option CUSTOM-HEADER : '%s'", MAX_CUSTOM_HTTP_HEADER, p[1]);
}
else
{
/* We will save p[2] and p[3], the proxy code will detect if
* p[3] is NULL */
custom_header->name = p[2];
custom_header->content = p[3];
}
}
else
{
msg (msglevel, "Bad http-proxy-option or missing parameter: '%s'", p[1]);
Expand Down
88 changes: 67 additions & 21 deletions src/openvpn/proxy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -488,6 +488,67 @@ http_proxy_close (struct http_proxy_info *hp)
free (hp);
}

bool
add_proxy_headers (struct http_proxy_info *p,
socket_descriptor_t sd, /* already open to proxy */
const char *host, /* openvpn server remote */
const char *port /* openvpn server port */
)
{
char buf[512];
int i;
bool host_header_sent=false;

/*
* Send custom headers if provided
* If content is NULL the whole header is in name
* Also remember if we already sent a Host: header
*/
for (i=0; i < MAX_CUSTOM_HTTP_HEADER && p->options.custom_headers[i].name;i++)
{
if (p->options.custom_headers[i].content)
{
openvpn_snprintf (buf, sizeof(buf), "%s: %s",
p->options.custom_headers[i].name,
p->options.custom_headers[i].content);
if (!strcasecmp(p->options.custom_headers[i].name, "Host"))
host_header_sent=true;
}
else
{
openvpn_snprintf (buf, sizeof(buf), "%s",
p->options.custom_headers[i].name);
if (!strncasecmp(p->options.custom_headers[i].name, "Host:", 5))
host_header_sent=true;
}

msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
if (!send_line_crlf (sd, buf))
return false;
}

if (!host_header_sent)
{
openvpn_snprintf (buf, sizeof(buf), "Host: %s", host);
msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
if (!send_line_crlf(sd, buf))
return false;
}

/* send User-Agent string if provided */
if (p->options.user_agent)
{
openvpn_snprintf (buf, sizeof(buf), "User-Agent: %s",
p->options.user_agent);
msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
if (!send_line_crlf (sd, buf))
return false;
}

return true;
}


bool
establish_http_proxy_passthru (struct http_proxy_info *p,
socket_descriptor_t sd, /* already open to proxy */
Expand Down Expand Up @@ -531,18 +592,8 @@ establish_http_proxy_passthru (struct http_proxy_info *p,
if (!send_line_crlf (sd, buf))
goto error;

openvpn_snprintf(buf, sizeof(buf), "Host: %s", host);
if (!send_line_crlf(sd, buf))
goto error;

/* send User-Agent string if provided */
if (p->options.user_agent)
{
openvpn_snprintf (buf, sizeof(buf), "User-Agent: %s",
p->options.user_agent);
if (!send_line_crlf (sd, buf))
goto error;
}
if (!add_proxy_headers (p, sd, host, port))
goto error;

/* auth specified? */
switch (p->auth_method)
Expand Down Expand Up @@ -657,14 +708,11 @@ establish_http_proxy_passthru (struct http_proxy_info *p,
if (!send_line_crlf (sd, buf))
goto error;


/* send HOST etc, */
openvpn_snprintf (buf, sizeof(buf), "Host: %s", host);
msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
if (!send_line_crlf (sd, buf))
goto error;
if (!add_proxy_headers (p, sd, host, port))
goto error;

msg (D_PROXY, "Attempting NTLM Proxy-Authorization phase 3");
msg (D_PROXY, "Attempting NTLM Proxy-Authorization phase 3");
{
const char *np3 = ntlm_phase_3 (p, buf2, &gc);
if (!np3)
Expand Down Expand Up @@ -770,9 +818,7 @@ establish_http_proxy_passthru (struct http_proxy_info *p,
goto error;

/* send HOST etc, */
openvpn_snprintf (buf, sizeof(buf), "Host: %s", host);
msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
if (!send_line_crlf (sd, buf))
if (!add_proxy_headers (p, sd, host, port))
goto error;

/* send digest response */
Expand Down
7 changes: 7 additions & 0 deletions src/openvpn/proxy.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,12 @@
#define HTTP_AUTH_NTLM2 4
#define HTTP_AUTH_N 5 /* number of HTTP_AUTH methods */

struct http_custom_header {
const char *name;
const char *content;
};

#define MAX_CUSTOM_HTTP_HEADER 10
struct http_proxy_options {
const char *server;
int port;
Expand All @@ -53,6 +59,7 @@ struct http_proxy_options {
const char *auth_file;
const char *http_version;
const char *user_agent;
struct http_custom_header custom_headers[MAX_CUSTOM_HTTP_HEADER];
};

struct http_proxy_options_simple {
Expand Down

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