[FFmpeg-devel] [PATCH] lavf/http: Export headers as AVDictionary

Nicolas George george at nsup.org
Sat Aug 22 11:00:37 CEST 2015

Le tridi 3 fructidor, an CCXXIII, Stephan Holljes a écrit :
> Actually I just noticed that Pragma-headers may appear multiple times.
> What would be a good way to handle that? I thought about expanding the
> header tag from "Pragma" to "Pragma-%02d" with either an incrementing
> number or just using s->nb_headers. Is there a better solution?

Well, this is annoying, I had hoped we could disregard duplicated headers as
a badly-formed request warranting sending nasal demons to the client.

Suffixing a number would be very impractical for the application, and would
cause strange behaviours if the client were to send a header with a number.

Another option would be to allow duplicated key entries in AVDictionary, but
that would require specifying the order of the entries.

Fortunately, the RFC saves us here:

   Multiple message-header fields with the same field-name MAY be
   present in a message if and only if the entire field-value for that
   header field is defined as a comma-separated list [i.e., #(values)].
   It MUST be possible to combine the multiple header fields into one
   "field-name: field-value" pair, without changing the semantics of the
   message, by appending each subsequent field-value to the first, each
   separated by a comma.

Therefore, when dealing with any header already present in the dictionary:
append a comma and the new value to it.

Note that FFserver's behaviour with regard to duplicated Pragma entries is
currently broken:

                if (av_strncasecmp(p, "Pragma: log-line=", 17) == 0) {
                    logline = p;
                if (av_strncasecmp(p, "Pragma: client-id=", 18) == 0)
                    client_id = strtol(p + 18, 0, 10);

That code recognizes:

	Pragma: log-line=foobar
	Pragma: client-id=bazqux

but not:

	Pragma: log-line=foobar,client-id=bazqux

Hopefully, fixing it would be a side effect of using the new HTTP server


  Nicolas George
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