[sipcore] Content-Length in multipart body parts

[Paul Kyzivat <[e-mail]>]

[reposting with a subject line]

On 4/2/12 6:53 PM, Worley, Dale R (Dale) wrote:
> Bruno Chatras has pointed out that a number of examples in various SIP-related
> RFCs show Content-Length header fields in the headers of body-parts of multipart
> entities.  MIME does not define the meaining of such header fields, as the MIME
> framing of body parts is done by the boundary markers.
>
> As Dale Moberg has pointed out, these header fields might not be truly incorrect
> but merely redundant or "to be ignored".
>
> But given that MIME multipart already frames the body-parts, Content-Length
> headers on body-parts are never necessary.
>
> So it seems to me that we should decide on a "best practices" for the use of
> Content-Length in the headers of a body part, to clarify the ambiguities in the
> specifications, and to state whether it's preferable to include such a Content-Length
> or not.
>
> I've appended a list of all the examples carrying such Content-Length headers
> that I could find by automated means.
>
> Dale
> --------------------------------------------------------------------------------------------------------
> RFC 2848
>
>                         The PINT Service Protocol:
>     Extensions to SIP and SDP for IP Access to Telephone Call Services
>
> Suspicious line at rfc2848.txt:2195:       Content-Length: 236
> Suspicious line at rfc2848.txt:2209:       Content-Length:50
> Suspicious line at rfc2848.txt:2268:       Content-Length: 316
> Suspicious line at rfc2848.txt:2284:       Content-Length: 172
> Suspicious line at rfc2848.txt:2372:    Content-Length: 325
> Suspicious line at rfc2848.txt:2387:    Content-Length: 352
>
> Several of these body-part headers are not separated from the
> body-part contents by CR-LF-CR-LF.
>
> RFC 3261
>
>                      SIP: Session Initiation Protocol
>
> Suspicious line at rfc3261.txt:11846:         Content-Length: 231
>
> RFC 3892
>
>        The Session Initiation Protocol (SIP) Referred-By Mechanism
>
> Suspicious line at rfc3892.txt:642:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:687:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:702:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:879:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:887:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:938:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:964:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:972:       Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:1056:      Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:1106:      Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:1168:      Content-Length: (appropriate value)
> Suspicious line at rfc3892.txt:1196:      Content-Length: (appropriate value)
>
> RFC 3893
>
>                     Session Initiation Protocol (SIP)
>                  Authenticated Identity Body (AIB) Format
>
> Suspicious line at rfc3893.txt:249:    Content-Length: 147
> (This has an extra CR-LF before the body-part headers.)
> Suspicious line at rfc3893.txt:263:    Content-Length: 608
>
> RFC 4463
>
>                  A Media Resource Control Protocol (MRCP)
>                Developed by Cisco, Nuance, and Speechworks
>
> Suspicious line at rfc4463.txt:1705:        Content-Length:176
> Suspicious line at rfc4463.txt:1714:        Content-Length:104
> Suspicious line at rfc4463.txt:2977:       Content-Length:176
> (Also missing the CR-LF after the body part headers.)
> Suspicious line at rfc4463.txt:2985:       Content-Length:104
>
> RFC 5547
>
>        A Session Description Protocol (SDP) Offer/Answer Mechanism
>                          to Enable File Transfer
>
> Suspicious line at rfc5547.txt:1645:    Content-Length: [length of SDP]
> Suspicious line at rfc5547.txt:1670:    Content-Length: [length of image]
> Suspicious line at rfc5547.txt:2093:    Content-Length: [length of SDP]
> Suspicious line at rfc5547.txt:2118:    Content-Length: [length of image]
>
> RFC 5589
>
>         Session Initiation Protocol (SIP) Call Control - Transfer
>
> Suspicious line at rfc5589.txt:2609:    Content-Length: 2961
> (An extra CR-LF in the middle of the body part headers.)
> Suspicious line at rfc5589.txt:2677:    Content-Length: 156
> (An extra CR-LF in the middle of the body part headers.)
> Suspicious line at rfc5589.txt:2696:    Content-Length: 2961
>
> RFC 6086
>
>    Session Initiation Protocol (SIP) INFO Method and Package Framework
>
> Suspicious line at rfc6086.txt:1594:    Content-length: 59
> Suspicious line at rfc6086.txt:1620:    Content-length: 59
> Suspicious line at rfc6086.txt:1637:    Content-length: 59
> Suspicious line at rfc6086.txt:1664:    Content-length: 59
> _______________________________________________
> sipcore mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/sipcore
>