Another small thing: continuation lines can start with horizontal tab in
addition to space.
Anders
Frank W. Miller wrote:
>
> I've been following this discussion for a bit. I agree that the grammar is
> probably overly permissive but it is what it is. Just for fun, I decided to
> contribute a bit here. In my implementation, I run the following little
> preprocessor bit over all incoming messages. The idea is to try to put the
> message in a little bit more "normal" form prior to parsing. This code is
> part of the Asterisk implementation as well when the "pendantic" option is
> turned on. It does a single pass over the message and collapses it
> "in-place" in the provided buffer. It can probably be improved so I'm
> interested in any and all comments. No license on this, use it as you
> will...
>
>
>
> #include <ctype.h>
> #include <stdlib.h>
>
> int
> lws2sws(char *msgbuf, int len)
> {
> int h = 0, t = 0;
> int lws = 0;
>
> if (msgbuf == NULL)
> return (-1);
>
> for (; h < len;) {
> /* Eliminate all CRs */
> if (msgbuf[h] == '\r') {
> h++;
> continue;
> }
> /* Check for end-of-line */
> if (msgbuf[h] == '\n') {
> /* Check for end-of-message */
> if (h + 1 == len)
> break;
>
> /* Check for a continuation line */
> if (msgbuf[h + 1] == ' ') {
> /* Merge continuation line */
> h++;
> continue;
> }
> /* Propagate LF and start new line */
> msgbuf[t++] = msgbuf[h++];
> lws = 0;
> continue;
> }
> if (msgbuf[h] == ' ' || msgbuf[h] == '\t') {
> if (lws) {
> h++;
> continue;
> }
> msgbuf[t++] = msgbuf[h++];
> lws = 1;
> continue;
> }
> msgbuf[t++] = msgbuf[h++];
> if (lws)
> lws = 0;
> }
> msgbuf[t] = '\0';
> return t;
> }
>
>
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Iñaki
> Baz Castillo
> Sent: Saturday, March 29, 2008 4:26 PM
> To: [email protected]
> Subject: Re: [Sip-implementors] Why SIP abnf is so permissive???
>
> El Sábado, 29 de Marzo de 2008, Valentin Nechayev escribió:
>> Your example
>> (b) is too radical, it's better to compare with something like:
>>
>> === c)
>> INVITE sip:[EMAIL PROTECTED] SIP/2.0
>> From : alice <[EMAIL PROTECTED]>; tag=1
>> To : white rabbit <[EMAIL PROTECTED]>; tag=2
>> i : [EMAIL PROTECTED]
>> ===
>>
>> which isn't much worse than non-spaced form.
>
> Sure it's not so bad, but for example I know some SIP devices/softphones
> that
> fail parsing a message with SP / HTAB between header field name and COLON.
> Probably no SIP implementation adds unnecesary SP / HTAB after COLON, so
> most
> of them can interoperate, but the risk is there.
>
>
>
>>> Ok, I understand that SIP was born from HTTP and so, but anyway I hope
> in
>>> a future SIP/X.0 appears eliminating so many and innecesary permissive
>>> syntax.
>> If to invent such, this already won't be text format
>
> Why not? I like SIP format, it's human readable (AFAIK one of its success
> cause) but IMHO a no so much flexible grammar could be nicer (no so much
> space allowed, no line folding... ) just it, I wouldn't like to see a binary
>
> format ;)
>
> Thanks a lot for your comment and explanation. Best regards.
>
>
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