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netfilter: nf_ct_sip: allow tab character in SIP headers

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Current parsing methods for SIP headers do not allow the presence of
tab characters between header name and header value. As a result Call-ID
SIP headers like the following are discarded by IPVS SIP persistence
engine:

"Call-ID\t: mycallid@abcde"
"Call-ID:\tmycallid@abcde"

In above examples Call-IDs are represented as strings in C language.
Obviously in real message we have byte "09" before/after colon (":").

Proposed fix is in nf_conntrack_sip module.
Function sip_skip_whitespace() should skip tabs in addition to spaces,
since in SIP grammar whitespace (WSP) corresponds to space or tab.

Below is an extract of relevant SIP ABNF syntax.

Call-ID  =  ( "Call-ID" / "i" ) HCOLON callid
callid   =  word [ "@" word ]

HCOLON  =  *( SP / HTAB ) ":" SWS
SWS     =  [LWS] ; sep whitespace
LWS     =  [*WSP CRLF] 1*WSP ; linear whitespace
WSP     =  SP / HTAB
word    =  1*(alphanum / "-" / "." / "!" / "%" / "*" /
           "_" / "+" / "`" / "'" / "~" /
           "(" / ")" / "<" / ">" /
           ":" / "\" / DQUOTE /
           "/" / "[" / "]" / "?" /
           "{" / "}" )

Signed-off-by: Marco Angaroni <marcoangaroni@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Marco Angaroni 2016-08-30 18:52:22 +02:00 committed by Pablo Neira Ayuso
parent 22609b43b1
commit 1bcabc81ee
1 changed files with 1 additions and 1 deletions
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2
net/netfilter/nf_conntrack_sip.c
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@ -330,7 +330,7 @@ static const char *sip_follow_continuation(const char *dptr, const char *limit)
static const char *sip_skip_whitespace(const char *dptr, const char *limit)
{
for (; dptr < limit; dptr++) {
if (*dptr == ' ')
if (*dptr == ' ' || *dptr == '\t')
continue;
if (*dptr != '\r' && *dptr != '\n')
break;