Rakesh privately asked me why this doesn't conform to the ABNF of a sip
message. I'm replying to the list for the benefit of others.
Here is some of the relevant ABNF:
SIP-message = Request / Response
Request = Request-Line
*( message-header )
CRLF
[ message-body ]
Request-Line = Method SP Request-URI SP SIP-Version CRLF
Method = INVITEm / ACKm / OPTIONSm / BYEm
/ CANCELm / REGISTERm
/ extension-method
extension-method = token
Response = Status-Line
*( message-header )
CRLF
[ message-body ]
Status-Line = SIP-Version SP Status-Code SP Reason-Phrase CRLF
SIP-Version = "SIP" "/" 1*DIGIT "." 1*DIGIT
token = 1*(alphanum / "-" / "." / "!" / "%" / "*"
/ "_" / "+" / "`" / "'" / "~" )
Examining this you can see that a message must start with one of the
following:
- a token - a method name
- "SIP/" - beginning a sip version
What you show is neither of those, so it isn't valid sip.
Over UDP every packet must start with a message. Over TCP, messages
immediately follow one another. Every request or response ends with CRLF
followed by an optional body. You must parse Content-Length in order to
skip over the body (which may also contain CRLF).
If you encounter something that doesn't parse as a message with TCP
input you have to close the connection without parsing any more, or else
use a heuristic to skip over stuff until you find what seems to be the
beginning of a new message.
Thanks,
Paul
> 0000 *ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff *
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
> 0010 * ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff*
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
> 0020 0000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
> 0010 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ
> 0020 ff ff ff ff ff ff ff ff ff ff ff 58 2d 42 72 6f
ÿÿÿÿÿÿÿÿÿÿÿX-xro
> 0030 61 64 57 6f 72 6b 73 2d 44 4e 43 3a 20 6e 65 74 : net
> 0040 77 6f 72 6b 2d 61 64 64 72 65 73 73 3d 22 73 69
work-address="si
> 0050 70 3a 2b 33 34 39 33 37 38 31 37 30 31 36 40 6d
p:@xx.yyy.net <mailto:p...@xx.yyy.net>
> 0070 74 3b 75 73 65 72 3d 70 68 6f 6e 65 22 3b 75 73
t;user=phone";us
> 0080 65 72 2d 69 64 3d 22 39 33 37 38 31 37 30 31 36
er-id="11111111"
> 0090 40 6d 66 65 2e 74 65 6c 65 66 6f 6e 69 63 61 2e @xx.yyy.
> 00a0 6e 65 74 22 0d 0a net"..
> ÿÿÿÿÿÿÿÿÿÿÿX-xro
> 0030 61 64 57 6f 72 6b 73 2d 44 4e 43 3a 20 6e 65 74 : net
> 0040 77 6f 72 6b 2d 61 64 64 72 65 73 73 3d 22 73 69
work-address="si
> 0050 70 3a 2b 33 34 39 33 37 38 31 37 30 31 36 40 6d
p:@xx.yyy.net <mailto:p...@xx.yyy.net>
> 0070 74 3b 75 73 65 72 3d 70 68 6f 6e 65 22 3b 75 73
t;user=phone";us
> 0080 65 72 2d 69 64 3d 22 39 33 37 38 31 37 30 31 36
er-id="11111111"
> 0090 40 6d 66 65 2e 74 65 6c 65 66 6f 6e 69 63 61 2e @xx.yyy.
> 00a0 6e 65 74 22 0d 0a net"..
>
> [image: image.png]
>
> BR///
>
> Rakesh Kumar Mohanty
>
>
> On Wed, Feb 6, 2019 at 3:21 PM Rakesh <rak...@gmail.com
<mailto:rak...@gmail.com>> wrote:
>
>> Hi Expert,
>>
>> Can I just know on INVITE request if I get the below characters
then is
>> it OK as per ABNF grammar? Please note I am not asking about
the header
>> rather I need to know the correctness of the character that has
appeared on
>> INVITE request.
>>
>>
>>
[truncated]\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\37
>> Expert Info (Note/Undecoded): Unrecognised SIP header
>> (�������������������������������������������)
>>
>> [image: image.png]
>> [image: image.png]
>>
>> BR///
>>
>> Rakesh Kumar Mohanty
>>
>
>
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