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[FFmpeg-devel] libavformat/http, tls: honor http_proxy command line variable for HTTPS

Message ID 20200820165050.GI4729@sunshine.barsnick.net
State New
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Series [FFmpeg-devel] libavformat/http, tls: honor http_proxy command line variable for HTTPS
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Commit Message

Moritz Barsnick Aug. 20, 2020, 4:50 p.m. UTC
Hi,

I gave $SUBJECT a shot. It's a bit of a weird situation, as "https" has
an underlying protocol "tls" which handles HTTPS specific stuff, but I
guess that's the layer cake the protocols give us.

So I needed to add an HTTPS specific option to the "tls" protocol, in
order to hand the option through. It's handling is then now identical
to the "http" implementation.

I tested this (before and after patch, with and without command line
option, with and without environment variable, with and without
reachable proxy server) against a local installation of tinyproxy.

Please review.

Thanks,
Moritz
From 095bb727b2400a75d6bf8c74ab90831aaefbc5aa Mon Sep 17 00:00:00 2001
From: Moritz Barsnick <barsnick@gmx.net>
Date: Thu, 20 Aug 2020 17:49:14 +0200
Subject: [PATCH] libavformat/http,tls: honor http_proxy command line variable
 for HTTPS

Add the "http_proxy" option and its handling to the "tls" protocol,
pass the option from the "https" protocol.

The "https" protocol already defines the "http_proxy" command line
option, like the "http" protocol does. The "http" protocol properly
honors that command line option in addition to the environment
variable. The "https" protocol doesn't, because the proxy is
evaluated in the underlying "tls" protocol, which doesn't have this
option, and thus only handles the environment variable, which it
has access to.

Documentation for the "tls" protocol is not changed, as the new
option is basically only useful together with the "https" protocol.

Fixes #7223.

Signed-off-by: Moritz Barsnick <barsnick@gmx.net>
---
 libavformat/http.c | 6 ++++++
 libavformat/tls.c  | 2 +-
 libavformat/tls.h  | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

--
2.26.2

Comments

Martin Storsjö Aug. 20, 2020, 7:05 p.m. UTC | #1
On Thu, 20 Aug 2020, Moritz Barsnick wrote:

> Add the "http_proxy" option and its handling to the "tls" protocol,
> pass the option from the "https" protocol.
> 
> The "https" protocol already defines the "http_proxy" command line
> option, like the "http" protocol does. The "http" protocol properly
> honors that command line option in addition to the environment
> variable. The "https" protocol doesn't, because the proxy is
> evaluated in the underlying "tls" protocol, which doesn't have this
> option, and thus only handles the environment variable, which it
> has access to.
> 
> Documentation for the "tls" protocol is not changed, as the new
> option is basically only useful together with the "https" protocol.

The patch looks fine in general, I think, but I don't agree with the last 
statement here.

Even if you do e.g. a plain tls socket (or rtmps, or whatever), you may 
want to do the tls connection through a proxy server (be that a socks 
proxy or http proxy).

For the case of rtmps, if you pass the http_proxy option, it should be 
passed to the rtmps protocol, which doesn't have such an option, from 
where it's passed along in the options dictionary down until the tls 
protocol consumes it. This just doesn't work for https, as the shared 
http/https options dictionary consumes the option from the dictionary, so 
you have to readd it like you do in your patch.

// Martin
Moritz Barsnick Aug. 20, 2020, 7:48 p.m. UTC | #2
Hej Martin,

On Thu, Aug 20, 2020 at 22:05:39 +0300, Martin Storsjö wrote:

> Even if you do e.g. a plain tls socket (or rtmps, or whatever), you may
> want to do the tls connection through a proxy server (be that a socks
> proxy or http proxy).

Actually, I forget that an HTTP proxy with CONNECT support cn transport
any plain socket. I will amend documentation to doc/*.texi.

> For the case of rtmps, if you pass the http_proxy option, it should be
> passed to the rtmps protocol, which doesn't have such an option, from
> where it's passed along in the options dictionary down until the tls
> protocol consumes it.

So you're saying it already works for rtmps, nothing needs to be
changed there? Fine.

Thanks for the review, will follow up with v2,
Moritz
Martin Storsjö Aug. 20, 2020, 7:51 p.m. UTC | #3
Hej,

On Thu, 20 Aug 2020, Moritz Barsnick wrote:

> Hej Martin,
>
> On Thu, Aug 20, 2020 at 22:05:39 +0300, Martin Storsjö wrote:
>
>> Even if you do e.g. a plain tls socket (or rtmps, or whatever), you may
>> want to do the tls connection through a proxy server (be that a socks
>> proxy or http proxy).
>
> Actually, I forget that an HTTP proxy with CONNECT support cn transport
> any plain socket. I will amend documentation to doc/*.texi.
>
>> For the case of rtmps, if you pass the http_proxy option, it should be
>> passed to the rtmps protocol, which doesn't have such an option, from
>> where it's passed along in the options dictionary down until the tls
>> protocol consumes it.
>
> So you're saying it already works for rtmps, nothing needs to be
> changed there? Fine.

I didn't test it, but from browsing the code, it looks like it would work.

// Martin
diff mbox series

Patch

diff --git a/libavformat/http.c b/libavformat/http.c
index 6c39da1a8b..21584bdce9 100644
--- a/libavformat/http.c
+++ b/libavformat/http.c
@@ -213,6 +213,12 @@  static int http_open_cnx_internal(URLContext *h, AVDictionary **options)
         use_proxy   = 0;
         if (port < 0)
             port = 443;
+        /* pass http_proxy to underlying protocol */
+        if (s->http_proxy) {
+            err = av_dict_set(options, "http_proxy", s->http_proxy, 0);
+            if (err < 0)
+                return err;
+        }
     }
     if (port < 0)
         port = 80;
diff --git a/libavformat/tls.c b/libavformat/tls.c
index 10e0792e29..302c0f8d59 100644
--- a/libavformat/tls.c
+++ b/libavformat/tls.c
@@ -89,7 +89,7 @@  int ff_tls_open_underlying(TLSShared *c, URLContext *parent, const char *uri, AV
     if (!c->host && !(c->host = av_strdup(c->underlying_host)))
         return AVERROR(ENOMEM);

-    proxy_path = getenv("http_proxy");
+    proxy_path = c->http_proxy ? c->http_proxy : getenv("http_proxy");
     use_proxy = !ff_http_match_no_proxy(getenv("no_proxy"), c->underlying_host) &&
                 proxy_path && av_strstart(proxy_path, "http://", NULL);

diff --git a/libavformat/tls.h b/libavformat/tls.h
index beb19d6d55..0c52ff3be6 100644
--- a/libavformat/tls.h
+++ b/libavformat/tls.h
@@ -34,6 +34,7 @@  typedef struct TLSShared {
     int listen;

     char *host;
+    char *http_proxy;

     char underlying_host[200];
     int numerichost;
@@ -49,6 +50,7 @@  typedef struct TLSShared {
     {"cert_file",  "Certificate file",                    offsetof(pstruct, options_field . cert_file), AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
     {"key_file",   "Private key file",                    offsetof(pstruct, options_field . key_file),  AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
     {"listen",     "Listen for incoming connections",     offsetof(pstruct, options_field . listen),    AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, .flags = TLS_OPTFL }, \
+    {"http_proxy", "set proxy to tunnel through when using HTTPS", offsetof(pstruct, options_field . http_proxy), AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }, \
     {"verifyhost", "Verify against a specific hostname",  offsetof(pstruct, options_field . host),      AV_OPT_TYPE_STRING, .flags = TLS_OPTFL }

 int ff_tls_open_underlying(TLSShared *c, URLContext *parent, const char *uri, AVDictionary **options);