[rtmpdump] Akamai authentication support

[Martin Storsjö]

Hi,

Some time ago, I had to push a stream to Akamai, and thus I looked into 
the two patches that were posted last year, that both achieve this. 
Unfortunately, they do that in two completely different ways, so I'm not 
sure which one is better, or if both of them should be integrated.

I'll repost polished up versions (fixed some out of bounds reads and 
memory leaks) of them shortly, but I'll try to explain the differences 
between them first.

The first one is by Sergiy, originally from May 2010, the other by David 
Keeffe from July/August 2010.

Both of them implement some kind of challenge/response authentication. By 
default, the FMS servers at akamai don't let you connect at all.

If adding flashver=FMLE/3.0\20(compatible;\20FMSc/1.0) to the rtmp url, 
the server will close the connection indicating that you need to 
authenticate with the adobe mode of authentication. On the second 
connection attempt, the client indicates which user it will try to 
authenticate as, the server closes the connection again (and supplies a 
challenge at the same time). On the third connection attempt, the client 
provides the username, the challenge received on the last attempt, and the 
response to the challenge. This authentication scheme is what FMLE uses 
(in the version I tried at least).

The second way of authenticating with these servers, as implemented by 
David Keeffe, requires you to add conn=S:encoder:1.2.3.4:<username> to the 
rtmp url. When this is added, the server lets the client in directly, and 
then sends the challenge and allows the client to respond to the challenge 
- all inline within one session.

Also, worth noting, when publishing to akami, the stream id given as 
playpath might contain a %i - FMLE changes this into a 1 (probably 
allowing several bitrate variants of the same content or something such), 
the user has to expand it manually with librtmp (this took me ages to hunt 
down...).

I don't have access to publishing to akamai myself at the moment 
unfortunately, I guess you want access to something such to test the 
patchsets before either of them can be merged.

// Martin