Hello, If you are expecting the user to supply the entirety of the To/From headers, than the only thing you can do is require the user to provide the length of each so that you can assign memory storage within your object/function appropriately. As Brett has said, and I have experienced in the field, you cannot make any assumptions about the lengths of ANY SIP header field. I have seen From headers get rather large because some implementations will include uri-params and like to use rather large from-tags.
For name-addr and addr-spec, it would probably be easier to make some sane approximations, but you have to consider that the standard does not impose any limit on these either. I would say the user of your API should be the one cognizant of lengths, and provide them to your API appropriately. Joel Gerber Network Operations Specialist - Telephone Telephone Eastlink joel.ger...@corp.eastlink.ca T: 519.786.1241 -----Original Message----- From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Arun Arora Sent: November-13-15 7:35 AM To: Brett Tate <br...@broadsoft.com>; sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip-implementors] Max length of To/ From headers Hmm.. That’s true, ‘No max should be there’ to support inter-op. However, for API design, I guess their is no way other than asking API-User to Provide the length of Strings for To and From. I am designing the API to receive the To/ From header in form or 'name-addr' or 'addr-spec' in order to avoid accessing any local db for getting domain-name to use in To/ From. The motivation is to make the library as much agnostic as possible from the local configurations saved in the implementation specific data-bases/ config files. Any thoughts…? Thanks, Arun On 13/11/15, 5:58 PM, "Brett Tate" <br...@broadsoft.com> wrote: >> Is their any specific length of To/ From header defined by the >> standard > >No. > > >> In case no specific length is defined, is their any common-practice >> for max length? > >RFC 3261 section 18.1.1 might provide you some guidance for message >size minimums to support. The common practice is not cap the >individual header sizes unless using really high maximum. From an >individual header perspective, the Via, Call-ID, Route, Record-Route, >and Contact tend to be larger than implementations originally might >think (especially when using comma-separated format); thus vendors >attempting to use maximum below 256 bytes for comma-separated segment >usually have to increase their caps for interoperability reasons. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
