chan_sip: Do not allow non-SP/HTAB between header key and colon.
authorWalter Doekes <walter+asterisk@wjd.nu>
Wed, 30 Nov 2016 15:31:39 +0000 (16:31 +0100)
committerMark Michelson <mmichelson@digium.com>
Thu, 8 Dec 2016 14:19:38 +0000 (08:19 -0600)
commitc796f00c35c43972bcbfa1cba55a8862f00248a9
treeb2fc9113c35fc7e9b0300d5a8f8edb4bb7c6c1b8
parent2268834c41d5b00a33c463c2cdc7113a85c94d6e
chan_sip: Do not allow non-SP/HTAB between header key and colon.

RFC says SIP headers look like:

    HCOLON  =  *( SP / HTAB ) ":" SWS
    SWS     =  [LWS]                    ; sep whitespace
    LWS     =  [*WSP CRLF] 1*WSP        ; linear whitespace
    WSP     =  SP / HTAB                ; from rfc2234

chan_sip implemented this:

    HCOLON  =  *( LOWCTL / SP ) ":" SWS
    LOWCTL  = %x00-1F                   ; CTL without DEL

This discrepancy meant that SIP proxies in front of Asterisk with
chan_sip could pass on unknown headers with \x00-\x1F in them, which
would be treated by Asterisk as a different (known) header.  For
example, the "To\x01:" header would gladly be forwarded by some proxies
as irrelevant, but chan_sip would treat it as the relevant "To:" header.

Those relying on a SIP proxy to scrub certain headers could mistakenly
get unexpected and unvalidated data fed to Asterisk.

This change fixes so chan_sip only considers SP/HTAB as valid tokens
before the colon, making it agree on the headers with other speakers of
SIP.

ASTERISK-26433 #close
AST-2016-009

Change-Id: I78086fbc524ac733b8f7f78cb423c91075fd489b
channels/chan_sip.c