Network Working Group                                     R. Sparks, Ed.
Internet-Draft                                               dynamicsoft
Expires: April 23, March 31, 2004                                   A. Hawrylyshen
                                                         Jasomi Networks
                                                             A. Johnston
                                                                     MCI
                                                            J. Rosenberg
                                                             dynamicsoft
                                                          H. Schulzrinne
                                                     Columbia University
                                                            October 24, 2003

           Session Initiation Protocol Torture Test Messages
                  draft-ietf-sipping-torture-tests-01
                  draft-ietf-sipping-torture-tests-02

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 23, March 31, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

   This informational document gives examples of Session Initiation
   Protocol (SIP) test messages designed to exercise and "torture" a
   parser.

Table of Contents

   1.       Overview . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.       Document Conventions . . . . . . . . . . . . . . . . . .   4
   2.1      Representing Long Lines  . . . . . . . . . . . . . . . .   4
   2.2      Representing Non-printable Characters  . . . . . . . . .   5
   2.3      Representing Long Repeating Strings  . . . . . . . . . .   5
   3.       SIP Test Messages  . . . . . . . . . . . . . . . . . . .   6
   3.1      Parser tests (syntax)  . . . . . . . . . . . . . . . . .   6
   3.1.1    Valid messages . . . . . . . . . . . . . . . . . . . . .   6
   3.1.1.1  A short tortuous INVITE  . . . . . . . . . . . . . . . .   6
   3.1.1.2  Wide range of valid characters . . . . . . . . . . . . .   8
   3.1.1.3  Valid use of the % escaping mechanism  . . . . . . . . .   9
   3.1.1.4  Escaped nulls in URIs  . . . . . . . . . . . . . . . . .  10
   3.1.1.5  Use of % when it is not an escape  . . . . . . . . . . .  11
   3.1.1.6  Message with no LWS between display name and < . . . . .  12
   3.1.1.7  Long values in header fields . . . . . . . . . . . . . .  12
   3.1.1.8  Extra trailing octets in a UDP datagram  . . . . . . . .  14
   3.1.1.9  Semicolon separated parameters in URI user part  . . . .  15
   3.1.1.10 Varied and unknown transport types . . . . . . . . . . .  15
   3.1.1.11 S/MIME signed message  . . . . . . . . . . . . . . . . .  16
   3.1.1.12 Unusual reason phrase  . . . . . . . . . . . . . . . . .  19
   3.1.1.13 Empty reason phrase  . . . . . . . . . . . . . . . . . .  20
   3.1.2    Invalid messages . . . . . . . . . . . . . . . . . . . .  20
   3.1.2.1  Extraneous header field separators . . . . . . . . . . .  20
   3.1.2.2  Content length larger than message . . . . . . . . . . .  21
   3.1.2.3  Negative Content-Length  . . . . . . . . . . . . . . . .  22
   3.1.2.4  Request scalar fields with overlarge values  . . . . . .  22
   3.1.2.5  Response scalar fields with overlarge values . . . . . .  23
   3.1.2.6  Unterminated quoted string in display-name . . . . . . .  24
   3.1.2.7  <> enclosing Request-URI . . . . . . . . . . . . . . . .  25
   3.1.2.8  Malformed SIP Request-URI (embedded LWS) . . . . . . . .  25
   3.1.2.9  Multiple SP separating Request-Line elements . . . . . .  26
   3.1.2.10 SP characters at end of Request-Line . . . . . . . . . .  27
   3.1.2.11 Escaped headers in SIP Request-URI . . . . . . . . . . .  27
   3.1.2.12 Invalid timezone in Date header field  . . . . . . . . .  28
   3.1.2.13 Failure to enclose name-addr URI in <> . . . . . . . . .  29
   3.1.2.14 Spaces within addr-spec  . . . . . . . . . . . . . . . .  29
   3.1.2.15 Non-token characters in display-name . . . . . . . . . .  30
   3.1.2.16 Unknown protocol version . . . . . . . . . . . . . . . .  30
   3.1.2.17 Start line and CSeq method mismatch  . . . . . . . . . .  31
   3.1.2.18 Unknown Method with CSeq method mismatch . . . . . . . .  31
   3.1.2.19 Overlarge response code  . . . . . . . . . . . . . . . .  32
   3.2      Transaction layer semantics  . . . . . . . . . . . . . .  32
   3.2.1    Missing transaction identifier . . . . . . . . . . . . .  32
   3.3      Application layer semantics  . . . . . . . . . . . . . .  33
   3.3.1    Missing Required Header Fields . . . . . . . . . . . . .  33
   3.3.2    Request-URI with unknown scheme  . . . . . . . . . . . .  33
   3.3.3    Request-URI with known but atypical scheme . . . . . . .  34
   3.3.4    Unknown URI schemes in header fields . . . . . . . . . .  34
   3.3.5    Proxy-Require and Require  . . . . . . . . . . . . . . .  35
   3.3.6    Unknown Content-Type . . . . . . . . . . . . . . . . . .  35
   3.3.7    Unknown authorization scheme . . . . . . . . . . . . . .  36
   3.3.8    Multiple values in single value required fields  . . . .  37
   3.3.9    Multiple Content-Length values . . . . . . . . . . . . .  37
   3.3.10   200 OK Response with broadcast Via header field value  .  38
   3.3.11   Max-Forwards of zero . . . . . . . . . . . . . . . . . .  39
   3.3.12   REGISTER with a contact header parameter . . . . . . . .  39
   3.3.13   REGISTER with a url parameter  . . . . . . . . . . . . .  40
   3.3.14   REGISTER with a url escaped header . . . . . . . . . . .  40
   3.3.15   Unacceptable Accept offering . . . . . . . . . . . . . .  41
   3.4      Backward compatibility . . . . . . . . . . . . . . . . .  42
   3.4.1    INVITE with RFC2543 syntax . . . . . . . . . . . . . . .  42
   4.       Security Considerations  . . . . . . . . . . . . . . . .  42
   5.       Open Issues and Remaining Work . . . . . . . . . . . . .  43
   6.       Acknowledgments  . . . . . . . . . . . . . . . . . . . .  43
            Informative References . . . . . . . . . . . . . . . . .  44
            Authors' Addresses . . . . . . . . . . . . . . . . . . .  44
   A.       Bit-exact archive of each test message . . . . . . . . .  45
   A.1      Encoded Reference Messages . . . . . . . . . . . . . . .  46
            Intellectual Property and Copyright Statements . . . . .  51  50

1. Overview

   This document is informational, and is NOT NORMATIVE on any aspect of
   SIP.

   This document contains test messages based on the current version
   (2.0) of the Session Initiation Protocol as defined in [RFC3261].
   Some messages exercise SIP's use of SDP as described in [RFC3264].

   These messages were developed and refined at the SIPIt
   interoperability test events.

   The test messages are organized into several sections. Some stress
   only a SIP parser and others stress both the parser and the
   application above it. Some messages are valid, and some are not. Each
   example clearly calls out what makes any invalid messages incorrect.

   This document does not attempt to catalog every way to make an
   invalid message, nor does it attempt to be comprehensive in exploring
   unusual, but valid, messages. Instead, it tries to focus on areas
   that have caused interoperability problems or have particularly
   unfavorable characteristics if they are handled improperly. This
   document is a seed for a test plan, not a test plan in itself.

   The messages are presented in the text using a set of markup
   conventions to avoid ambiguity and meet Internet-Draft layout
   requirements. To resolve any remaining ambiguity, a bit-accurate
   version of each message is encapsulated in an appendix.

2. Document Conventions

   This document contains many example SIP messages. Although SIP is a
   text-based protocol, many of these examples cannot be unambiguously
   rendered without additional markup due to the constraints placed on
   the formatting of RFCs. This document defines and uses the markup
   defined in this section to remove that ambiguity. This markup uses
   the start and end tag conventions of XML, but does not define any XML
   document type.

   The appendix contains an encoded binary form of all the messages and
   the algorithm needed to decode them into files.

2.1 Representing Long Lines

   Several of these examples contain unfolded lines longer than 72
   characters. These are captured between <allOneLine/> tags. The single
   unfolded line is reconstructed by directly concatenating all lines
   appearing between the tags (discarding any line-feeds or carriage
   returns). There will be no whitespace at the end of lines. Any
   whitespace appearing at a fold-point will appear at the beginning of
   a line.

   The following represent the same string of bits:

      Header-name: first value, reallylongsecondvalue, third value

      <allOneLine>
      Header-name: first value,
       reallylongsecondvalue
      , third value
      </allOneLine>

      <allOneLine>
      Header-name: first value,
       reallylong
      second
      value,
       third value
      </allOneLine>

    Note that this is NOT SIP header line folding where different
   strings of bits have equivalent meaning.

2.2 Representing Non-printable Characters

   Several examples contain binary message bodies or header field values
   containing non-ascii range UTF-8 encoded characters. These are
   rendered here as a pair of hexadecimal digits per octet between <hex/
   > tags. This rendering applies even inside quoted-strings.

   The following represent the same string of bits:

     Header-name: value one

     Header-name: value<hex>206F6E</hex>e

   The following is a Subject header field containing the euro symbol:

      Subject: <hex>E282AC</hex>

2.3 Representing Long Repeating Strings

   Several examples contain very large data values created with
   repeating bit strings. Those will be rendered here using <repeat
   count=some_integer>value</repeat>. As with <hex> this rendering
   applies even inside quoted-strings.

   For example, the value "abcabcabc" can be rendered as <repeat
   count=3>abc</repeat>. A display name of "1000000 bottles of beer"
   could be rendered as

     To: "1<repeat count=6><hex>30</hex></repeat> bottles of beer"
         <sip:beer.example.com>

    and a Max-Forwards header field with a value of one google will be
   rendered here as

      Max-Forwards: 1<repeat count=100>0</repeat>

3. SIP Test Messages

3.1 Parser tests (syntax)

3.1.1 Valid messages

3.1.1.1 A short tortuous INVITE

   This short, relatively human-readable message contains:

   o  line folding all over

   o  escaped characters within quotes

   o  an empty subject

   o  LWS between colons, semicolons, header field values, and other
      fields

   o  both comma separated and separate listing of header field values

   o  mix or short and long form for the same header field name

   o  unknown header fields

   o  unknown header field with a value that would be syntactically
      invalid if it were defined in terms of generic-param

   o  unusual header field ordering

   o  unusual header field name character case
   o  unknown parameters of a known header field

   o  uri parameter with no value

   o  header parameter with no value

   o  integer fields (Max-Forwards and CSeq) with leading zeros

   All elements should treat this as a well-formed request.

   The UnknownHeaderWithUnusualValue header field deserves special
   attention. If this header field were defined in terms of comma
   separated values with semicolon separated parameters (as many of the
   existing defined header fields), this would be invalid. However,
   since the receiving element does not know the definition of the
   syntax for this field, it must parse it as a header-value. Proxies
   would forward this header field unchanged. Endpoints would ignore the
   header field.

      Message Details : wsinv

      INVITE sip:vivekg@chair-dnrc.example.com;unknownparam SIP/2.0
      TO :
       sip:vivekg@chair-dnrc.example.com ;   tag    = 1918181833n
      from   : "J Rosenberg \\\""       <sip:jdrosen@example.com>
        ;
        tag = 98asjd8
      MaX-fOrWaRdS: 0068
      Call-ID: 0ha0isndaksdj@192.0.2.1
      Content-Length   : 151
      cseq: 0009
        INVITE
      Via  : SIP  /   2.0
       /UDP
          192.0.2.2;branch=390skdjuw
      s :
      NewFangledHeader:   newfangled value
       continued newfangled value
      UnknownHeaderWithUnusualValue: ;;,,;;,;
      Content-Type: application/sdp
      Route:
       <sip:services.example.com;lr;unknownwith=value;unknown-no-value>
      v:  SIP  / 2.0  / TCP     spindle.example.com   ;
        branch  =   z9hG4bK9ikj8  ,
       SIP  /    2.0   / UDP  192.168.255.111   ; branch=
       z9hG4bK30239
      m:"Quoted string \"\"" <sip:jdrosen@example.com> ; newparam =
      newvalue ;
        secondparam ; q = 0.33

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.3
      s=-
      c=IN IP4 192.0.2.4
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.1.2 Wide range of valid characters

   This message exercises a wider range of characters in several key
   syntactic elements than implementations usually see. Of particular
   note:

   o  The Method contains non-alpha characters from token. Note that %
      is not an escape character for this field. A method of IN%56ITE is
      an unknown method. It is not the same as a method of INVITE

   o  The Request-URI contain unusual, but legal, characters

   o  A branch parameter contains all non-alphanum characters from token

   o  The To header field value's quoted-string contains quoted-pair
      expansions, including a quoted NULL character

   o  The name part of name-addr in the From header field value contains
      multiple tokens (instead of a quoted string) with all non-alphanum
      characters from the token production rule. That value also has an
      unknown header parameter whose name contains the non-alphanum
      token characters and whose value is a non-ascii range UTF-8
      encoded string. The tag parameter on this value contains the
      non-alphanum token characters

   o  The Call-ID header field value contains the non-alphanum
      characters from word. Notice that in this production:

      *  % is not an escape character. (It is only an escape character
         in productions matching the rule "escaped")

      *  " does not start a quoted-string. None of ',` or " imply that
         there will be a matching symbol later in the string

      *  The characters []{}()<> do not have any grouping semantics.
         They are not required to appear in balanced pairs
   o  There is an unknown header field (matching extension-header) with
      non-alphanum token characters in its name and a UTF8-NONASCII
      value

   If this unusual URI has been defined at a proxy, the proxy will
   forward this request normally. Otherwise a proxy will generate a 404.
   Endpoints will generate a 501 listing the methods they understand in
   an Allow header field.

      Message Details : intmeth

      <allOneLine>
      !interesting-Method0123456789_*+`.%indeed'~
       sip:1_unusual.URI~(to-be!sure)&isn't+it$/crazy?,/;;*
      :&it+has=1,weird!*pas$wo~d_too.(doesn't-it)
      @example.com SIP/2.0
      </allOneLine>
      Via: SIP/2.0/TCP host1.example.com;branch=z9hG4bK-.!%66*_+`'~
      <allOneLine>
      To: "BEL:\<hex>07</hex> NUL:\<hex>00</hex> DEL:\<hex>7F</hex>"
       <sip:1_unusual.URI~(to-be!sure)&isn't+it$/crazy?,/;;*
      @example.com>
      </allOneLine>
      <allOneLine>
      From: token1~` token2'+_ token3*%!.- <sip:mundane@example.com>
      ;fromParam''~+*_!.-%=
      "<hex>D180D0B0D0B1D0BED182D0B0D18ED189D0B8D0B9</hex>"
      ;tag=_token~1'+`*%!-.
      </allOneLine>
      Call-ID: word%ZK-!.*_+'@word`~)(><:\/"][?}{
      CSeq: 139122385 !interesting-Method0123456789_*+`.%indeed'~
      Max-Forwards: 255
      <allOneLine>
      extensionHeader-!.%*+_`'~=
      <hex>EFBBBFE5A4A7E5819CE99BBB</hex>
      </allOneLine>
      Content-Length: 0

3.1.1.3 Valid use of the % escaping mechanism

   This INVITE exercises the % HEX HEX escaping mechanism in several
   places. The request is syntactically valid. Interesting features
   include:

   o  The request-URI has sips:user@example.com embedded in its
      userpart. What that might mean to example.net is beyond the scope
      of this document.

   o  The From and To URIs have escaped characters in their userparts.

   o  The Contact URI has escaped characters in the URI parameters. Note
      that the "name" uri-parameter has a value of "value%41" which is
      NOT equivalent to "valueA". Per [RFC2396], unescaping URI
      components is never performed recursively.

   A parser must accept this as a well-formed message. The application
   using the message must treat the % HEX HEX expansions as equivalent
   to the character being encoded. The application must not try to
   interpret % as an escape character in those places where % HEX HEX
   ("escaped" in the grammar) is not a valid part of the construction.
   In [RFC3261], "escaped" only occurs in the expansions of SIP-URI,
   SIPS-URI, and Reason-Phrase

      Message Details : esc01

      INVITE sip:sips%3Auser%40example.com@example.net SIP/2.0
      To: sip:%75se%72@example.com
      From: <sip:I%20have%20spaces@example.net>;tag=938
      Max-Forwards: 87
      i: 239409asdfakjkn23onasd0-3234
      CSeq: 234234 INVITE
      Via: SIP/2.0/UDP host5.example.net;branch=z9hG4bKkdjuw
      C: application/sdp
      Contact:
        <sip:cal%6Cer@host5.example.net;%6C%72;n%61me=v%61lue%25%34%31>
      Content-Length: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.1.4 Escaped nulls in URIs

   This register request contains several URIs with nulls in the
   userpart. The message is well formed - parsers must accept this
   message. Implementations must take special care when unescaping the
   AOR in this request to not prematurely shorten the username. This
   request registers two distinct contact URIs.

      Message Details : escnull

      REGISTER sip:example.com SIP/2.0
      To: sip:null-%00-null@example.com
      From: sip:null-%00-null@example.com;tag=839923423
      Max-Forwards: 70
      Call-ID: 39203ndfvkjdasfkq3w4otrq0adsfdfnavd
      CSeq: 14398234 REGISTER
      Via: SIP/2.0/UDP host5.example.com;branch=z9hG4bKkdjuw
      Contact: <sip:%00@host5.example.com>
      Contact: <sip:%00%00@host5.example.com>
      L:0

3.1.1.5 Use of % when it is not an escape

   Most of the places % can appear in a SIP message, it is not an escape
   character. This can surprise the unwary implementor. The following
   well-formed request has these properties:

   o  The request method is unknown. It is NOT equivalent to REGISTER

   o  The display-name portion of the To and From header fields is
      "%Z%45". Note that this is not the same as %ZE

   o  This message has two Contact header field values, not three.
      %lt;sip:alias2@host2.example.com%gt; is a C%6Fntact header field
      value

   A parser should accept this message as well formed. A proxy would
   forward or reject the message depending on what the Request-URI meant
   to it. An endpoint would reject this message with a 501.

      Message Details : esc02

      RE%47IST%45R sip:registrar.example.com SIP/2.0
      To: "%Z%45" <sip:resource@example.com>
      From: "%Z%45" <sip:resource@example.com>;tag=f232jadfj23
      Call-ID: asdfnqwo34rq23i34jrjasdcnl23nrlknsdf
      Via: SIP/2.0/TCP host.example.com;branch=z9hG4bK209%fzsnel234
      CSeq: 29344 RE%47IST%45R
      Max-Forwards: 70
      Contact: <sip:alias1@host1.example.com>
      C%6Fntact: <sip:alias2@host2.example.com>
      Contact: <sip:alias3@host3.example.com>
      l: 0

3.1.1.6 Message with no LWS between display name and <

   This OPTIONS request is not valid per the grammar in RFC 3261. since
   there is no LWS between the quoted string in the display name and <
   in the From header field value. This has been identified as a
   specification bug that will be removed when RFC 3261 is revised.
   Elements should accept this request as well formed.

      Message Details : lwsdisp

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:user@example.com
      From: "caller"<sip:caller@example.com>;tag=323
      Max-Forwards: 70
      Call-ID: 1234abcd@funky.example.com
      CSeq: 60 OPTIONS
      Via: SIP/2.0/UDP funky.example.com;branch=z9hG4bKkdjuw
      l: 0

3.1.1.7 Long values in header fields

   This well-formed request contains header fields with many values and
   values that are very long. Features include:

   o  The To header field has a long display name, and long uri
      parameter names and values

   o  The From header field has long header parameter names and values,
      in particular a very long tag

   o  The Call-ID is one long token

      Message Details : longreq

      INVITE sip:user@example.com SIP/2.0
      <allOneLine>
      To: "I have a user name of
       <repeat count=10>extreme</repeat> proportion"
      <sip:user@example.com:6000;
      unknownparam1=very<repeat count=20>long</count>value;
      longparam<repeat count=25>name</repeat>=shortvalue;
      very<repeat count=25>long</count>ParameterNameWithNoValue>
      </allOneLine>
      <allOneLine>
      F: sip:

      <repeat count=5>amazinglylongcallername</repeat>@example.net
      ;tag=12<repeat count=50>982</repeat>424
      ;unknownheaderparam<repeat count=20>name</count>=
      unknowheaderparam<repeat count=15>value</count>
      ;unknownValueless<repeat count=10>paramname</count>
      </allOneLine>
      Call-ID: one<repeat count=20>really</repeat>longcallid
      CSeq: 3882340 INVITE
      <allOneLine>
      Unknown-<repeat count=20>Long</repeat>-Name:
       unknown-<repeat count=20>long</repeat>-value;
       unknown-<repeat count=20>long</repeat>-parameter-name =
       unknown-<repeat count=20>long</repeat>-parameter-value
      </allOneLine>
      Via: SIP/2.0/TCP sip33.example.com
      v: SIP/2.0/TCP sip32.example.com
      V: SIP/2.0/TCP sip31.example.com
      Via: SIP/2.0/TCP sip30.example.com
      ViA: SIP/2.0/TCP sip29.example.com
      VIa: SIP/2.0/TCP sip28.example.com
      VIA: SIP/2.0/TCP sip27.example.com
      via: SIP/2.0/TCP sip26.example.com
      viA: SIP/2.0/TCP sip25.example.com
      vIa: SIP/2.0/TCP sip24.example.com
      vIA: SIP/2.0/TCP sip23.example.com
      V :  SIP/2.0/TCP sip22.example.com
      v :  SIP/2.0/TCP sip21.example.com
      V  : SIP/2.0/TCP sip20.example.com
      v  : SIP/2.0/TCP sip19.example.com
      Via : SIP/2.0/TCP sip18.example.com
      Via  : SIP/2.0/TCP sip17.example.com
      Via: SIP/2.0/TCP sip16.example.com
      Via: SIP/2.0/TCP sip15.example.com
      Via: SIP/2.0/TCP sip14.example.com
      Via: SIP/2.0/TCP sip13.example.com
      Via: SIP/2.0/TCP sip12.example.com
      Via: SIP/2.0/TCP sip11.example.com
      Via: SIP/2.0/TCP sip10.example.com
      Via: SIP/2.0/TCP sip9.example.com
      Via: SIP/2.0/TCP sip8.example.com
      Via: SIP/2.0/TCP sip7.example.com
      Via: SIP/2.0/TCP sip6.example.com
      Via: SIP/2.0/TCP sip5.example.com
      Via: SIP/2.0/TCP sip4.example.com
      Via: SIP/2.0/TCP sip3.example.com
      Via: SIP/2.0/TCP sip2.example.com
      Via: SIP/2.0/TCP sip1.example.com
      <allOneLine>
      Via: SIP/2.0/TCP
      host.example.com;received=192.0.2.5;
      branch=very<repeat count=50>long</repeat>branchvalue
      </allOneLine>
      Max-Forwards: 70
      <allOneLine>
      Contact: <sip:
      <repeat count=5>amazinglylongcallername</repeat>
      @host5.example.net>
      </allOneLine>
      Content-Type: application/sdp
      l: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.1.8 Extra trailing octets in a UDP datagram

   This message contains a single SIP REGISTER request, which ostensibly
   arrived over UDP in a single datagram. The packet contained extra
   octets after the body (which in this case has zero length). Those
   octets happen to look like a SIP INVITE request, but (per section
   18.3 of [RFC3261]) they are just spurious noise that must be ignored.

   A SIP element receiving this datagram would handle the REGISTER
   request normally and ignore the extra bits that look like an INVITE
   request. If the element is a proxy choosing to forward the REGISTER,
   the INVITE octets would not appear in the forwarded request.

      Message Details : dblreq

      REGISTER sip:example.com SIP/2.0
      To: sip:j.user@example.com
      From: sip:j.user@example.com;tag=43251j3j324
      Max-Forwards: 8
      I: 0ha0isndaksdj99sdfafnl3lk233412
      Contact: sip:j.user@host.example.com
      CSeq: 8 REGISTER
      Via: SIP/2.0/UDP 192.0.2.125;branch=z9hG4bKkdjuw23492
      Content-Length: 0
      INVITE sip:joe@example.com SIP/2.0
      t: sip:joe@example.com
      From: sip:caller@example.net;tag=141334
      Max-Forwards: 8
      Call-ID: 0ha0isnda977644900765@192.0.2.15
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP 192.0.2.15;branch=z9hG4bKkdjuw380234
      Content-Type: application/sdp
      Content-Length: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.15
      s=-
      c=IN IP4 192.0.2.15
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m =video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.1.9 Semicolon separated parameters in URI user part

   This request has a semicolon-separated parameter contained in the
   "user" part of the Request-URI (whose value contains an escaped @
   symbol). Receiving elements will accept this as a well formed
   message. The Request-URI will parse such that the user part is
   "user;par=u@example.net".

      Message Details : semiuri

      OPTIONS sip:user;par=u%40example.net@example.com SIP/2.0
      To: sip:j_user@example.com
      From: sip:caller@example.org;tag=33242
      Max-Forwards: 3
      Call-ID: 0ha0isndaksdj
      CSeq: 8 OPTIONS
      Accept: application/sdp, application/pkcs7-mime,
              multipart/mixed, multipart/signed,
              message/sip, message/sipfrag
      Via: SIP/2.0/UDP 192.0.2.1;branch=z9hG4bKkdjuw
      l: 0

3.1.1.10 Varied and unknown transport types

   This request contains Via header field values with all known
   transport types and exercises the transport extension mechanism.
   Parsers must accept this message as well formed. Elements receiving
   this message would process it exactly as if the 2nd and subsequent
   header field values specified UDP (or other transport).

      Message Details : transports

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:user@example.com
      From: <sip:caller@example.com>;tag=323
      Max-Forwards: 70
      Call-ID:  nfc9ehfdfaekijh4akdnaqjkwendsasfdj
      Accept: application/sdp
      CSeq: 60 OPTIONS
      Via: SIP/2.0/UDP t1.example.com;branch=z9hG4bKkdjuw
      Via: SIP/2.0/SCTP t2.example.com;branch=z9hG4bKklasjdhf
      Via: SIP/2.0/TLS t3.example.com;branch=z9hG4bK2980unddj
      Via: SIP/2.0/UNKNOWN t4.example.com;branch=z9hG4bKasd0f3en
      Via: SIP/2.0/TCP t5.example.com;branch=z9hG4bK0a9idfnee
      l: 0

3.1.1.11 S/MIME signed message

   This is a signed INVITE request. The signature is binary encoded. The
   body contains null (0x00) characters. Receivers must take care to
   properly frame the received message.

   Parsers must accept this message as well formed, even if the
   application above the parser does not support multipart/signed.

      Message Details : smime01

      INVITE sip:receiver@example.com SIP/2.0
      Via: SIP/2.0/UDP host5.example.org;branch=z9hG4bK923rnasdkl3
      To: <sip:receiver@example.com>
      From: <sip:sender@example.org>;tag=2390234seiu3
      Call-ID: afnkjeriuoqeiuavnklafekjq34iu43uawe
      CSeq: 282398492 INVITE
      Max-Forwards: 70
      Contact: <sip:sender@host5.example.org>
      Content-Length: 3134
      Content-Type: multipart/signed;
                    protocol="application/pkcs-7-signature";
                    micalg=sha1;
                    boundary="----34CF59C076641DD0879594444157C7EB"
      ------34CF59C076641DD0879594444157C7EB
      Content-Type: message/sip

      INVITE sip:receiver@example.com SIP/2.0
      Via: SIP/2.0/UDP host5.example.org;branch=z9hG4bK923rnasdkl3
      To: <sip:receiver@example.com>
      From: <sip:sender@example.org>;tag=2390234seiu3
      Call-ID: afnkjeriuoqeiuavnklafekjq34iu43uawe
      CSeq: 282398492 INVITE
      Max-Forwards: 70
      Contact: <sip:sender@host5.example.org>
      Accept: application/sdp, application/pkcs7-mime,
              multipart/mixed, multipart/signed,
              message/sip, message/sipfrag
      Content-Type: application/sdp
      Content-Length: 149

      v=0
      o=sender 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

      ------34CF59C076641DD0879594444157C7EB
      Content-Type: application/pkcs-7-signature; name="smime.p7s"
      Content-Transfer-Encoding: binary
      Content-Disposition: attachment; filename="smime.p7s"

      <hex>3082088806092A86
      4886F70D010702A082087930820875020101310B300906052B0E03021A050030
      0B06092A864886F70D010701A082067A30820339308202A2A003020102020800
      90008902240001300D06092A864886F70D01010505003070310B300906035504
      0613025553311330110603550408130A43616C69666F726E69613111300F0603
      550407130853616E4A6F7365310E300C060355040A1305736970697431293027
      060355040B135369706974546573744365727469666963617465417574686F72
      697479301E170D3033313032313134343332355A170D31333130313831343433
      32355A3062310B3009060355040613025553311330110603550408130A43616C
      69666F726E69613111300F0603550407130853616E4A6F7365310E300C060355
      040A13057369706974311B30190603550403141273656E646572406578616D70
      6C652E6F726730819F300D06092A864886F70D010101050003818D0030818902
      818100CB8302060F12C8FA2D1786922CA173DCEB80BF1B1B8AF74A310C6975A5
      56A7630FB6E044D9E994DCD49AFF7976C462D7A8E74ECBF98723AEBF2796EDDD
      6263577C6C2B77DC7C300B533DEDB5FB8EB3827FD6FC9B37B9A0DE829F1B1081
      D632A8AD9FB00A860928E88F87E0B979BA65294AC7D6D2D18A78C86B4FA73387
      4E230203010001A381E93081E6301D0603551D1104163014811273656E646572
      406578616D706C652E6F726730090603551D1304023000301D0603551D0E0416
      041440FF1C0C1BB8684CA917839D70E97DF8DD5B60D130819A0603551D230481
      9230818F80146B461714EA94762580546E1354DAA1E35414A1B6A174A4723070
      310B3009060355040613025553311330110603550408130A43616C69666F726E
      69613111300F0603550407130853616E4A6F7365310E300C060355040A130573
      6970697431293027060355040B13536970697454657374436572746966696361
      7465417574686F72697479820100300D06092A864886F70D0101050500038181
      006FFE1A3B5CE807C3DD2CFDF6E9787F491C84DBF7DCD11DB2D6A8887D2FE3F2
      2E9C6894994282E50AA0DFFE1CBD4EC2C20217831FC2AD360FF1C0DE1DE1E870
      102CFA99EE504C7DC0D8752A63294AC748DDDEFADE55C6D051F1CD54CFE7C153
      278962A53CEF61B875C1FD3C74E972242CBA0131B3B8C607BF95B378212CA9A7
      5E30820339308202A2A00302010202080090008902240001300D06092A864886
      F70D01010505003070310B300906035504061302555331133011060355040813
      0A43616C69666F726E69613111300F0603550407130853616E4A6F7365310E30
      0C060355040A1305736970697431293027060355040B13536970697454657374
      4365727469666963617465417574686F72697479301E170D3033313032313134
      343332355A170D3133313031383134343332355A3062310B3009060355040613
      025553311330110603550408130A43616C69666F726E69613111300F06035504
      07130853616E4A6F7365310E300C060355040A13057369706974311B30190603
      550403141273656E646572406578616D706C652E6F726730819F300D06092A86
      4886F70D010101050003818D0030818902818100CB8302060F12C8FA2D178692
      2CA173DCEB80BF1B1B8AF74A310C6975A556A7630FB6E044D9E994DCD49AFF79
      76C462D7A8E74ECBF98723AEBF2796EDDD6263577C6C2B77DC7C300B533DEDB5
      FB8EB3827FD6FC9B37B9A0DE829F1B1081D632A8AD9FB00A860928E88F87E0B9
      79BA65294AC7D6D2D18A78C86B4FA733874E230203010001A381E93081E6301D
      0603551D1104163014811273656E646572406578616D706C652E6F7267300906
      03551D1304023000301D0603551D0E0416041440FF1C0C1BB8684CA917839D70
      E97DF8DD5B60D130819A0603551D2304819230818F80146B461714EA94762580
      546E1354DAA1E35414A1B6A174A4723070310B30090603550406130255533113
      30110603550408130A43616C69666F726E69613111300F060355040713085361
      6E4A6F7365310E300C060355040A1305736970697431293027060355040B1353
      69706974546573744365727469666963617465417574686F7269747982010030
      0D06092A864886F70D0101050500038181006FFE1A3B5CE807C3DD2CFDF6E978
      7F491C84DBF7DCD11DB2D6A8887D2FE3F22E9C6894994282E50AA0DFFE1CBD4E
      C2C20217831FC2AD360FF1C0DE1DE1E870102CFA99EE504C7DC0D8752A63294A
      C748DDDEFADE55C6D051F1CD54CFE7C153278962A53CEF61B875C1FD3C74E972
      242CBA0131B3B8C607BF95B378212CA9A75E318201D6308201D2020101307C30
      70310B3009060355040613025553311330110603550408130A43616C69666F72
      6E69613111300F0603550407130853616E4A6F7365310E300C060355040A1305
      736970697431293027060355040B135369706974546573744365727469666963
      617465417574686F7269747902080090008902240001300906052B0E03021A05
      00A081B1301806092A864886F70D010903310B06092A864886F70D010701301C
      06092A864886F70D010905310F170D3033313032323135323930325A30230609
      2A864886F70D010904311604144A2FD5856B6006413209FA56A0C1D85179DBCB
      5F305206092A864886F70D01090F31453043300A06082A864886F70D0307300E
      06082A864886F70D030202020080300D06082A864886F70D0302020140300706
      052B0E030207300D06082A864886F70D0302020128300D06092A864886F70D01
      01010500048180C1C3193CF4A8BE1278B5529ACFA1C51DDEDECF0D3DC4C18FC5
      9A5B120E6D559F4953A3C3C7C97B4EAD8388F1508F7AD2FC71CC7B9ED2844789
      60A3ECF87984E25A15B4AB63F150C30570B6315A2327E381EE11E866DC1405DA
      29E74CC20201816F1516DD893332D9A8E26FBAEC237C494F3EFAEF4EBCD2122C
      DE7D57DECD</hex>------34CF59C076641DD0879594444157C7EB--

3.1.1.12 Unusual reason phrase

   This 200 response contains a reason phrase other than "OK". The
   reason phrase is intended for human consumption, and may contain any
   string produced by

       Reason-Phrase   =  *(reserved / unreserved / escaped
                          / UTF8-NONASCII / UTF8-CONT / SP / HTAB)

   This particular response contains unreserved and non-ASCII UTF-8
   characters.This response is well formed. A parser must accept this
   message.

      Message Details : unreason

      <allOneLine>
      SIP/2.0 200 = 2**3 * 5**2 <hex>D0BDD0BE20D181D182
      D0BE20D0B4D0B5D0B2D18FD0BDD0BED181D182D0BE20D0B4
      D0B5D0B2D18FD182D18C202D20D0BFD180D0BED181D182D0
      BED0B5</hex>
      </allOneLine>
      Via: SIP/2.0/UDP 192.0.2.198;branch=z9hG4bK1324923
      Call-ID: 0384840201234ksdfak3j2erwedfsASdf
      CSeq: 35 INVITE
      From: sip:user@example.com;tag=11141343
      To: sip:user@example.edu;tag=2229
      Content-Length: 159
      Content-Type: application/sdp
      Contact: <sip:user@host198.example.com>

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.198
      s=-
      c=IN IP4 192.0.2.198/127
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.1.13 Empty reason phrase

   This well formed response contains no reason phrase. A parser must
   accept this message. The space character after the reason code is
   required. If it were not present, this message could be rejected as
   invalid (a liberal receiver would accept it anyway).

      Message Details : noreason

      SIP/2.0 100<hex>20</hex>
      Via: SIP/2.0/UDP 192.0.2.105;branch=z9hG4bK2398ndaoe
      Call-ID: adsn2309jasndj203insdf99223ndf
      CSeq: 35 INVITE
      From: <sip:user@example.com>;tag=39ansfi3
      To: <sip:user@example.edu>;tag=902jndnke3
      Content-Length: 0
      Contact: <sip:user@host105.example.com>

3.1.2 Invalid messages

   This section contains several invalid messages reflecting errors seen
   at interoperability events and exploring important edge conditions
   that can be induced through malformed messages. This section does not
   attempt to be a comprehensive list of all types of invalid messages.

3.1.2.1 Extraneous header field separators

   The Via and header field of this request contains contain additional
   semicolons and commas without parameters or values. The Contact
   header field contains additional semicolons without parameters. This
   message is syntactically invalid.

   An element receiving this request should respond with a 400 Bad
   Request error.

      Message Details : badinv01

      INVITE sip:user@example.com SIP/2.0
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=134161461246
      Max-Forwards: 7
      Call-ID: 0ha0isndaksdjasdf3234nas
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP 192.0.2.15;;,;,,
      Contact: "Joe" <sip:joe@example.org>;;;;
      Content-Length: 153
      Content-Type: application/sdp

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.15
      s=-
      c=IN IP4 192.0.2.15
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.2 Content length larger than message

   This is a request message with a Content Length that is larger than
   the length of the body.

   When sent UDP (as this message ostensibly was), the receiving element
   should respond with a 400 Bad Request error. If this message were
   received over a stream-based transport such as TCP, there's not much
   you can do but wait for more data on the stream and close the
   connection if none is forthcoming in a reasonable period of time.

      Message Details : clerr

      INVITE sip:user@example.com SIP/2.0
      Max-Forwards: 80
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=93942939o2
      Contact: <sip:caller@hungry.example.net>
      Call-ID: 0ha0isndaksdjweiafasdk3
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP host5.example.com;branch=z9hG4bK-39234-23523
      Content-Type: application/sdp
      Content-Length: 9999

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.155
      s=-
      c=IN IP4 192.0.2.155
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.3 Negative Content-Length

   This request has a negative value for Content-Length.

   An element receiving this message should respond with an error. This
   request appeared over UDP, so the remainder of the datagram can
   simply be discarded. If a request like this arrives over TCP, the
   framing error is not recoverable and the connection should be closed.
   The same behavior is appropriate for messages that arrive without a
   numeric value in the Content-Length header field such as:

       Content-Length: five

   Implementors should take extra precautions if the technique they
   choose for converting this ascii field into an integral form can
   return a negative value. In particular, the result must not be used
   as a counter or array index.

      Message Details : ncl

      INVITE sip:user@example.com SIP/2.0
      Max-Forwards: 254
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=32394234
      Call-ID: 0ha0isndaksdj2193423r542w35
      CSeq: 0 INVITE
      Via: SIP/2.0/UDP 192.0.2.53;branch=z9hG4bKkdjuw
      Contact: <sip:caller@example53.example.net>
      Content-Type: application/sdp
      Content-Length: -999

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.53
      s=-
      c=IN IP4 192.0.2.53
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.4 Request scalar fields with overlarge values

   This request contains several scalar header field values outside
   their legal range.

   o  the CSeq sequence number is >2**32-1.

   o  the Max-Forwards value is >255.

   o  the Expires value is >2**32-1.

   o  the Contact expires parameter value is >2**32-1.

   An element receiving this request should respond with a 400 Bad
   Request due to the CSeq error. If only the Max-Forwards field were in
   error, the element could choose process the request as if the field
   were absent. If only the expiry values were in error, the element
   could treat them as if they contained the default values for
   expiration (3600 in this case).

   Other scalar request fields that may contain aberrant values include,
   but are not limited to,  the Contact q value, the Timestamp value,
   and the Via ttl parameter.

      Message Details : scalar02

      REGISTER sip:example.com SIP/2.0
      Via: SIP/2.0/TCP host129.example.com;branch=z9hG4bK342sdfoi3
      To: <sip:user@example.com>
      From: <sip:user@example.com>;tag=239232jh3
      CSeq: 36893488147419103232 REGISTER
      Call-ID: asdnw3qjr23o0pd9vanlq3wnrlnewofjas9ui32
      Max-Forwards: 300
      Expires: 1<repeat count=100>0</repeat>
      Contact: <sip:user@host129.example.com>
        ;expires=280297596632815
      Content-Length: 0

3.1.2.5 Response scalar fields with overlarge values

   This response contains several scalar header field values outside
   their legal range.

   o  the CSeq sequence number is >2**32-1.

   o  The Retry-After field is unreasonably large (note that RFC 3261
      does not define a legal range for this field).

   o  The Warning field has a warning-value with more than 3 digits

   An element receiving this response will simply discard it.

      Message Details : scalarlg
      SIP/2.0 503 Service Unavailable
      Via: SIP/2.0.TCP host129.example.com;branch=z0hG4bKzzxdiwo34sw
      To: <sip:user@example.com>
      From: <sip:other@example.net>;tag=2easdjfejw
      CSeq: 9292394834772304023312 OPTIONS
      Call-ID: nvoao34irnoase0of0234hn2qofoaf0232aewf2394r
      Retry-After: 949302838503028349304023988
      Warning: 1812 overture "In Progress"
      Content-Length: 0

3.1.2.6 Unterminated quoted string in display-name

   This is a request with an unterminated quote in the display name of
   the To field. An element receiving this request should return an 400
   Bad Request error.

   An element could attempt to infer a terminating quote and accept the
   message. Such an element needs to take care that it makes a
   reasonable inference when it encounters

      To: "Mr J. User <sip:j.user@example.com> <sip:realj@example.net>

      Message Details : quotbal

      INVITE sip:user@example.com SIP/2.0
      To: "Mr. J. User <sip:j.user@example.com>
      From: sip:caller@example.net;tag=93334
      Max-Forwards: 10
      Call-ID: 0ha0isndaksdj
      Contact: <sip:caller@host59.example.net>
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP 192.0.2.59:5050;branch=z9hG4bKkdjuw39234
      Content-Type: application/sdp
      Content-Length: 153

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.15
      s=-
      c=IN IP4 192.0.2.15
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.7 <> enclosing Request-URI

   This INVITE request is invalid because the Request-URI has been
   enclosed within in "<>".

   It is reasonable to always reject a request with this error with a
   400 Bad Request. Elements attempting to be liberal with what they
   accept may choose to ignore the brackets. If the element forwards the
   request, it must not include the brackets in the messages it sends.

      Message Details : ltgtruri

      INVITE <sip:user@example.com> SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=39291
      Max-Forwards: 23
      Call-ID: 1@192.0.2.5
      CSeq: 1 INVITE
      Via: SIP/2.0/UDP 192.0.2.5
      Contact: <sip:caller@host5.example.net>
      Content-Type: application/sdp
      Content-Length: 160

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.5
      s=-
      c=IN IP4 192.0.2.5
      t=3149328700 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.8 Malformed SIP Request-URI (embedded LWS)

   This INVITE has illegal LWS within the Request-URI.

   An element receiving this request should respond with a 400 Bad
   Request.

   An element could attempt to ignore the embedded LWS for those schemes
   (like sip) where that would not introduce ambiguity.

      Message Details : lwsruri

      INVITE sip:user@example.com; lr SIP/2.0
      To: sip:user@example.com;tag=3xfe-9921883-z9f
      From: sip:caller@example.net;tag=231413434
      Max-Forwards: 5
      Call-ID: asdfasdoijweoi2323-asdfwern23-asd8ia0swn34rk423
      CSeq: 2130706432 INVITE
      Via: SIP/2.0/UDP 192.0.2.1:5060;branch=z9hG4bKkdjuw2395
      Contact: <sip:caller@host1.example.net>
      Content-Type: application/sdp
      Content-Length: 160

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=3149328700 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.9 Multiple SP separating Request-Line elements

   This INVITE has illegal multiple SP characters between elements of
   the start line.

   It is acceptable to reject this request as malformed. An element that
   is liberal in what it accepts may ignore these extra SP characters
   while processing the request. If the element forwards the request, it
   must not include these extra SP characters in the messages it sends.

      Message Details : lwsstart

      INVITE  sip:user@example.com  SIP/2.0
      Max-Forwards: 8
      To: sip:user@example.com
      From: sip:caller@example.net;tag=8814
      Call-ID: 2304u0qwsdfknq234oi243099adsdfnawe3@example.com
      CSeq: 1893884 INVITE
      Via: SIP/2.0/UDP host1.example.com;branch=z9hG4bKkdjuw3923
      Contact: <sip:caller@host1.example.net>
      Content-Type: application/sdp
      Content-Length: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.10 SP characters at end of Request-Line

   This OPTIONS request contains SP characters between the SIP-Version
   field and the CRLF terminating the Request-Line.

   It is acceptable to reject this request as malformed. An element that
   is liberal in what it accepts may ignore these extra SP characters
   while processing the request. If the element forwards the request, it
   must not include these extra SP characters in the messages it sends.

      Message Details : trws

      OPTIONS sip:remote-target@example.com SIP/2.0<hex>2020</hex>
      Via: SIP/2.0/TCP host1.examle.com;branch=z9hG4bK299342093
      To: <sip:remote-target@example.com>
      From: <sip:local-resource@example.com>;tag=329429089
      Call-ID: afewroicu34958239neffasdhr2345r
      Accept: application/sdp
      CSeq: 238923 OPTIONS
      Max-Forwards: 70
      Content-Length: 0

3.1.2.11 Escaped headers in SIP Request-URI

   This INVITE is malformed as the SIP Request-URI contains escaped
   headers.

   It is acceptable for an element to reject this request with a 400 Bad
   Request. An element could choose to be liberal in what it accepts and
   ignore the escaped headers. If the element is a proxy, the escaped
   headers must not appear in the Request-URI of forwarded request (and
   most certainly must not be translated into the actual header of the
   forwarded request).

      Message Details : escruri

      INVITE sip:user@example.com?Route=%3Csip:example.com%3E SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=341518
      Max-Forwards: 7
      Contact: <sip:caller@host39923.example.net>
      Call-ID: 23940-asdfhj-aje3br-234q098w-fawerh2q-h4n5
      CSeq: 149209342 INVITE
      Via: SIP/2.0/UDP host-of-the-hour.example.com;branch=z9hG4bKkdjuw
      Content-Type: application/sdp
      Content-Length: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      s=-
      c=IN IP4 192.0.2.1
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.12 Invalid timezone in Date header field

   This INVITE is invalid as it contains a non GMT time zone in the SIP
   Date header field.

   It is acceptable to reject this request as malformed (though an
   element shouldn't do that unless the contents of the Date header
   field were actually important to its processing).  An element wishing
   to be liberal in what it accepts could ignore this value altogether
   if it wasn't going to use the Date header field anyhow. Otherwise, it
   could attempt to interpret this date and adjust it to GMT.

   RFC 3261 explicitly defines the only acceptable timezone designation
   as "GMT". "UT", while synonymous with GMT per [RFC2822], is not
   valid. "UTC" and "UCT" are also invalid.

      Message Details : baddate

      INVITE sip:user@example.com SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=2234923
      Max-Forwards: 70
      Call-ID: 239423mnsadf3j23lj42--sedfnm234
      CSeq: 1392934 INVITE
      Via: SIP/2.0/UDP host.example.com;branch=z9hG4bKkdjuw
      Date: Fri, 01 Jan 2010 16:00:00 EST
      Contact: <sip:caller@host5.example.net>
      Content-Type: application/sdp
      Content-Length: 151

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.5
      s=-
      c=IN IP4 192.0.2.5
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.13 Failure to enclose name-addr URI in <>

   This REGISTER request is malformed. The SIP URI contained in the
   Contact Header field has an escaped header, so the field must be in
   name-addr form (which implies the URI must be enclosed in <>).

   It is reasonable for an element receiving this request to respond
   with a 400 Bad Request. An element choosing to be liberal in what it
   accepts could infer the angle brackets since there is no ambiguity in
   this example. In general, that won't be possible.

      Message Details : regbadct

      REGISTER sip:example.com SIP/2.0
      To: sip:user@example.com
      From: sip:user@example.com;tag=998332
      Max-Forwards: 70
      Call-ID: k345asrl3fdbv@10.0.0.1
      CSeq: 1 REGISTER
      Via: SIP/2.0/UDP 135.180.130.133:5060;branch=z9hG4bKkdjuw
      Contact: sip:user@example.com?Route=%3Csip:sip.example.com%3E
      l: 0

3.1.2.14 Spaces within addr-spec

   This request is malformed since the addr-spec in the To header field
   contains spaces. Parsers receiving this request must not break. It is
   reasonable to reject this request with a 400 Bad Request response.
   Elements attempting to be liberal may ignore the spaces.

      Message Details : badaspec

      OPTIONS sip:user@example.org SIP/2.0
      Via: SIP/2.0/UDP host4.example.com:5060;branch=z9hG4bKkdju43234
      Max-Forwards: 70
      From: "Bell, Alexander" <sip:a.g.bell@example.com>;tag=433423
      To: "Watson, Thomas" < sip:t.watson@example.org >
      Call-ID: sdf0234n2nds0a099u23h3hnnw009cdkne3
      Accept: application/sdp
      CSeq: 3923239 OPTIONS
      l: 0

3.1.2.15 Non-token characters in display-name

   This OPTIONS request is malformed since  the display names in the To
   and From header fields contain non-token characters but are unquoted.

   It is reasonable to always reject this kind of error with a 400 Bad
   Request response.

   An element may attempt to be liberal in what it receives and infer
   the missing quotes. If this element were a proxy, it must not
   propagate the error into the request it forwards. As a consequence,
   if the fields are covered by a signature, there's not much point in
   trying to be liberal - the message should be simply rejected.

      Message Details : baddn

      OPTIONS sip:t.watson@example.org SIP/2.0
      Via:     SIP/2.0/UDP c.example.com:5060;branch=z9hG4bKkdjuw
      Max-Forwards:      70
      From:    Bell, Alexander <sip:a.g.bell@example.com>;tag=43
      To:      Watson, Thomas <sip:t.watson@example.org>
      Call-ID: 31415@c.example.com
      Accept: application/sdp
      CSeq:    3923239 OPTIONS
      l: 0

3.1.2.16 Unknown protocol version

   To an element implementing [RFC3261], this request is malformed due
   to its high version number.

   The element should respond to the request with a 505 Version Not
   Supported error.

      Message Details : badvers

      OPTIONS sip:t.watson@example.org SIP/7.0
      Via:     SIP/7.0/UDP c.example.com;branch=z9hG4bKkdjuw
      Max-Forwards:     70
      From:    A. Bell <sip:a.g.bell@example.com>;tag=qweoiqpe
      To:      T. Watson <sip:t.watson@example.org>
      Call-ID: 31417@c.example.com
      CSeq:    1 OPTIONS
      l: 0

3.1.2.17 Start line and CSeq method mismatch

   This request has mismatching values for the method in the start line
   and the CSeq header field. Any element receiving this request will
   respond with a 400 Bad Request.

      Message Details : mismatch01

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=34525
      Max-Forwards: 6
      Call-ID: 0ha0isndaksdj0234sxdfl3
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP host.example.com;branch=z9hG4bKkdjuw
      l: 0

3.1.2.18 Unknown Method with CSeq method mismatch

   This message has an unknown method, and a CSeq method tag which does
   not match it.

   Any element receiving this response will should respond with a 501
   Not Implemented. A 400 Bad Request is also acceptable, but choosing a
   501 (particularly at proxies) has better future-proof
   characteristics.

      Message Details : mismatch02

      NEWMETHOD sip:user@example.com SIP/2.0
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=34525
      Max-Forwards: 6
      Call-ID: 0ha0isndaksdj0234sxdfl3
      CSeq: 8 INVITE
      Contact: <sip:caller@host.example.net>
      Via: SIP/2.0/UDP host.example.net;branch=z9hG4bKkdjuw
      Content-Type: application/sdp
      l: 139

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.1
      c=IN IP4 192.0.2.1
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.1.2.19 Overlarge response code

   This response has a response code larger than 699. An element
   receiving this response should simply drop it.

      Message Details : bigcode

      SIP/2.0 4294967301 better not break the receiver
      Via: SIP/2.0/UDP 192.0.2.105;branch=z9hG4bK2398ndaoe
      Call-ID: asdof3uj203asdnf3429uasdhfas3ehjasdfas9i
      CSeq: 353494 INVITE
      From: <sip:user@example.com>;tag=39ansfi3
      To: <sip:user@example.edu>;tag=902jndnke3
      Content-Length: 0
      Contact: <sip:user@host105.example.com>

3.2 Transaction layer semantics

   This section contains tests that exercise an implementation's parser
   and transaction layer logic.

3.2.1 Missing transaction identifier

   This request indicates support for RFC 3261-style transaction
   identifiers by providing the z9hG4bK prefix to the branch parameter,
   but it provides no identifier. A parser must not break when receiving
   this message. An element receiving this request could reject the
   request with a 400 Response (preferably statelessly, as other
   requests from the source are likely to also have a malformed branch
   parameter), or it could fall back to the RFC 2543 style transaction
   identifier.

      Message Details : badbranch

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.org;tag=33242
      Max-Forwards: 3
      Via: SIP/2.0/UDP 192.0.2.1;branch=z9hG4bK
      Accept: application/sdp
      Call-ID: sadonfo23i420jv0as0derf3j3n
      CSeq: 8 OPTIONS
      l: 0

3.3 Application layer semantics

   This section contains tests that exercise an implementation's parser
   and application layer logic.

3.3.1 Missing Required Header Fields

   This request contains no Call-ID, From, or To header fields.

   An element receiving this message must not break because of the
   missing information. Ideally, it will respond with a 400 Bad Request
   error.

      Message Details : insuf

      INVITE sip:user@example.com SIP/2.0
      CSeq: 193942 INVITE
      Via: SIP/2.0/UDP 192.0.2.95;branch=z9hG4bKkdjuw
      Content-Type: application/sdp
      l: 153

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.95
      s=-
      c=IN IP4 192.0.2.95
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.3.2 Request-URI with unknown scheme

   This OPTIONS contains an unknown URI scheme in the Request-URI. A
   parser must accept this as a well-formed SIP request.

   An element receiving this request will reject it with a 416
   Unsupported URI Scheme response.

   Some early implementations attempt to look at the contents of the To
   header field to determine how to route this kind of request. That is
   an error. Despite the fact that the To header field and the Request
   URI frequently look alike in simplistic first-hop messages, the To
   header field contains no routing information.

      Message Details : unkscm

      OPTIONS nobodyKnowsThisScheme:totallyopaquecontent SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=384
      Max-Forwards: 3
      Call-ID: 2340923nasdfasser0q239nwsdfasdkl34
      CSeq: 3923423 OPTIONS
      Via: SIP/2.0/TCP host9.example.com;branch=z9hG4bKkdjuw39234
      Content-Length: 0

3.3.3 Request-URI with known but atypical scheme

   This OPTIONS contains an Request-URI with an IANA registered scheme
   that does not commonly appear Request-URIs of SIP requests. A parser
   must accept this as a well-formed SIP request.

   If an element will never accept this scheme as meaningful in a
   request-URI, it is appropriate to treat it as unknown and return a
   416 Unsupported URI Scheme response. If the element might accept some
   URIs with this scheme, then a 404 Not Found is appropriate for those
   URIs it doesn't accept.

      Message Details : novelsc

      OPTIONS soap.beep://192.0.2.103:3002 SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=384
      Max-Forwards: 3
      Call-ID: 2340923nasdfasser0q239nwsdfasdkl34
      CSeq: 3923423 OPTIONS
      Via: SIP/2.0/TCP host9.example.com;branch=z9hG4bKkdjuw39234
      Content-Length: 0

3.3.4 Unknown URI schemes in header fields

   This message contains registered schemes in the To, From and Contact
   header fields of a request. The message is syntactically valid.
   Parsers must not fail when receiving this message.

   Proxies should treat this message as they would any other request for
   this URI. A registrar would reject this request with a 400 Bad
   Request response since the To: header field is required to contain a
   SIP or SIPS URI as an AOR.

      Message Details : unksm2

      REGISTER sip:example.com SIP/2.0
      To: isbn:2983792873
      From: <http://www.example.com>;tag=3234233
      Call-ID: 0ha0isndaksdj@hyphenated-host.example.com
      CSeq: 234902 REGISTER
      Max-Forward: 70
      Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
      Contact: <name:John_Smith>
      l: 0

3.3.5 Proxy-Require and Require

   This request tests proper implementation of SIP's Proxy-Require and
   Require extension mechanisms.

   Any element receiving this request will respond with a 420 Bad
   Extension response containing an Unsupported header field listing
   these features from either the Require or Proxy-Require header field
   depending on the role in which the element is responding.

      Message Details : bext01

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:j_user@example.com
      From: sip:caller@example.net;tag=242etr
      Max-Forward: 6
      Call-ID: 0ha0isndaksdj
      Require: nothingSupportsThis, nothingSupportsThisEither
      Proxy-Require: noProxiesSupportThis, norDoAnyProxiesSupportThis
      CSeq: 8 OPTIONS
      Via: SIP/2.0/TLS fold-and-staple.example.com;branch=z9hG4bKkdjuw
      Content-Length: 0

3.3.6 Unknown Content-Type

   This INVITE request contains a body of unknown type. It is
   syntactically valid. A parser must not fail when receiving it.

   A proxy receiving this request would process it just like any other
   INVITE. An endpoint receiving this request would reject it with a 415
   Unsupported Media Type error.

      Message Details : invut

      INVITE sip:user@example.com SIP/2.0
      Contact: <sip:caller@host5.example.net>
      To: sip:j.user@example.com
      From: sip:caller@example.net;tag=8392034
      Max-Forwards: 70
      Call-ID: 0ha0isndaksdjadsfij34n23d
      CSeq: 235448 INVITE
      Via: SIP/2.0/UDP somehost.example.com;branch=z9hG4bKkdjuw
      Content-Type: application/unknownformat
      Content-Length: 40

      <audio>
       <pcmu port="443"/>
      </audio>

3.3.7 Unknown authorization scheme

   This REGISTER request contains an Authorization header field with an
   unknown scheme. The request is well-formed. A parser must not fail
   when receiving it.

   A proxy will treat this request as any other REGISTER. If it forwards
   the request, it will include this Authorization header field
   unmodified in the forwarded messages.

   A registrar that does not care about challenge-response
   authentication will simply ignore the Authorization header field,
   processing this registration as if the field were not present. A
   registrar that does care about challenge-response authentication will
   reject this request with a 401, issuing a new challenge with a scheme
   it understands.

   Endpoints choosing not to act as registrars will simply reject the
   request. A 405 Method Not Allowed is appropriate.

      Message Details : regaut01

      REGISTER sip:example.com SIP/2.0
      To: sip:j.user@example.com
      From: sip:j.user@example.com;tag=87321hj23128
      Max-Forwards: 8
      Call-ID: 0ha0isndaksdj
      CSeq: 9338 REGISTER
      Via: SIP/2.0/TCP 192.0.2.253;branch=z9hG4bKkdjuw
      Authorization: NoOneKnowsThisScheme opaque data here
      Content-Length:0

3.3.8 Multiple values in single value required fields

   The message contains a request with multiple Call-ID, To, From,
   Max-Forwards and CSeq values. An element receiving this request must
   not break.

   An element receiving this request would respond with a 400 Bad
   Request error.

      Message Details : multi01

      INVITE sip:user@company.com SIP/2.0
      Contact: <sip:caller@host25.example.net>
      Via: SIP/2.0/UDP 192.0.2.25;branch=z9hG4bKkdjuw
      Max-Forwards: 70
      CSeq: 5 INVITE
      Call-ID: 98asdh@192.0.2.1
      CSeq: 59 INVITE
      Call-ID: 98asdh@192.0.2.2
      From: sip:caller@example.com;tag=3413415
      To: sip:user@example.com
      To: sip:other@example.net
      From: sip:caller@example.net;tag=2923420123
      Content-Type: application/sdp
      l: 155
      Contact: <sip:caller@host36.example.net>
      Max-Forwards: 5

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.25
      s=-
      c=IN IP4 192.0.2.25
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.3.9 Multiple Content-Length values

   Multiple conflicting Content-Length header field values appear in
   this request.

   From a framing perspective, this situation is equivalent to an
   invalid Content-Length value (or no value at all).

   An element receiving this message should respond with an error. This
   request appeared over UDP, so the remainder of the datagram can
   simply be discarded. If a request like this arrives over TCP, the
   framing error is not recoverable and the connection should be closed.

      Message Details : mcl01

      OPTIONS sip:user@example.com SIP/2.0
      Via: SIP/2.0/UDP host5.example.net;branch=z9hG4bK293423
      To: sip:user@example.com
      From: sip:other@example.net;tag=3923942
      Call-ID: 234asdfhn2323orihawfdoa3o4r52o3irsdf
      CSeq: 15932 OPTIONS
      Content-Length: 13
      Max-Forwards: 60
      Content-Length: 5
      Content-Type: text/plain

      There's no way to know how many octets are supposed to be here.

3.3.10 200 OK Response with broadcast Via header field value

   This message is a response with a 2nd Via header field value's
   sent-by containing 255.255.255.255. The message is well formed -
   parsers must not fail when receiving it.

   Per [RFC3261] an endpoint receiving this message should simply
   discard it.

   If a proxy followed normal response processing rules blindly, it
   would forward this response to the broadcast address. To protect
   against this being used as an avenue of attack, proxies should drop
   such responses.

      Message Details : bcast

      SIP/2.0 200 OK
      Via: SIP/2.0/UDP 192.0.2.198;branch=z9hG4bK1324923
      Via: SIP/2.0/UDP 255.255.255.255;branch=z9hG4bK1saber23
      Call-ID: 0384840201234ksdfak3j2erwedfsASdf
      CSeq: 35 INVITE
      From: sip:user@example.com;tag=11141343
      To: sip:user@example.edu;tag=2229
      Content-Length: 159
      Content-Type: application/sdp
      Contact: <sip:user@host28.example.com>
      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.198
      s=-
      c=IN IP4 192.0.2.198/127
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.3.11 Max-Forwards of zero

   This is a legal SIP request with the Max-Forwards header field value
   set to zero.

   A proxy should not forward the request and respond 483 (Too Many
   Hops). An endpoint should process the request as if the Max-Forwards
   field value were still positive.

      Message Details : zeromf

      OPTIONS sip:user@example.com SIP/2.0
      To: sip:user@example.com
      From: sip:caller@example.net;tag=3ghsd41
      Call-ID: 2304sadjfasdlfnm2o2l43r5u0asdfas
      CSeq: 39234321 OPTIONS
      Via: SIP/2.0/UDP host1.example.com;branch=z9hG4bKkdjuw2349i
      Max-Forwards: 0
      Content-Length: 0

3.3.12 REGISTER with a contact header parameter

   This register request contains a contact where the 'unknownparam'
   parameter must be interpreted as being a contact-param and not a
   url-param.

   This REGISTER should succeed. The response must not include
   "unknownparam" as a url-parameter for this binding. Likewise,
   "unknownparam" must not appear as part of the binding during
   subsequent fetches.

   Behavior is the same, of course, for any known contact-param
   parameter names.

      Message Details : cparam01
      REGISTER sip:example.com SIP/2.0
      Via: SIP/2.0/UDP saturn.example.com:5060;branch=z9hG4bKkdjuw
      Max-Forwards: 70
      From: sip:watson@example.com;tag=DkfVgjkrtMwaerKKpe
      To: sip:watson@example.com
      Call-ID: 70710@saturn.example.com
      CSeq: 2 REGISTER
      Contact: sip:+19725552222@gw1.example.net;unknownparam
      l: 0

3.3.13 REGISTER with a url parameter

   This register request contains a contact where the URI has an unknown
   parameter.

   The register should succeed and a subsequent retrieval of the
   registration must include "unknownparam" as a url-parameter.

   Behavior is the same, of course, for any known url-parameter names.

      Message Details : cparam02

      REGISTER sip:example.com SIP/2.0
      Via: SIP/2.0/UDP saturn.example.com:5060;branch=z9hG4bKkdjuw
      Max-Forwards: 70
      From: sip:watson@example.com;tag=838293
      To: sip:watson@example.com
      Call-ID: 70710@saturn.example.com
      CSeq: 3 REGISTER
      Contact: <sip:+19725552222@gw1.example.net;unknownparam>
      l: 0

3.3.14 REGISTER with a url escaped header

   This register request contains a contact where the URI has an escaped
   header.

   The register should succeed and a subsequent retrieval of the
   registration must include the escaped Route header in the contact URI
   for this binding.

      Message Details : regescrt

      REGISTER sip:example.com SIP/2.0
      To: sip:user@example.com
      From: sip:user@example.com;tag=8
      Max-Forwards: 70
      Call-ID: k345asrl3fdbv@192.0.2.1
      CSeq: 14398234 REGISTER
      Via: SIP/2.0/UDP host5.example.com;branch=z9hG4bKkdjuw
      M: <sip:user@example.com?Route=%3Csip:sip.example.com%3E>
      L:0

3.3.15 Unacceptable Accept offering

   This request indicates the response must contain a body in an unknown
   type. In particular, since the Accept header field does not contain
   application/sdp, the response may not contain an SDP body. The
   recipient of this request could respond with a 406 Not Acceptable
   with a Warning/399 indicating that a response cannot be formulated in
   the formats offered in the Accept header field. It is also
   appropriate to respond with a 400 Bad Request since all SIP UAs
   supporting INVITE are required to support application/sdp.

      Message Details : sdp01

      INVITE sip:user@example.com SIP/2.0
      To: sip:j_user@example.com
      Contact: <sip:caller@host15.example.net>
      From: sip:caller@example.net;tag=234
      Max-Forwards: 5
      Call-ID: 0ha0isndaksdj9342dasdd
      Accept: text/nobodyKnowsThis
      CSeq: 8 INVITE
      Via: SIP/2.0/UDP 192.0.2.15;branch=z9hG4bKkdjuw
      Content-Length: 151
      Content-Type: application/sdp

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.5
      s=-
      c=IN IP4 192.0.2.5
      t=0 0
      m=audio 492170 RTP/AVP 0 12
      m=video 3227 RTP/AVP 31
      a=rtpmap:31 LPC

3.4 Backward compatibility

3.4.1 INVITE with RFC2543 syntax

   This is a legal message per RFC 2543 (and several bis versions) which
   should be accepted by RFC 3261 elements which want to maintain
   backwards compatibility.

   o  There is no branch parameter at all on the Via header field value

   o  There is no From tag

   o  There is no explicit Content-Length (The body is assumed to be all
      octets in the datagram after the null-line)

   o  There is no Max-Forwards header field

      Message Details : inv2543

      INVITE sip:UserB@example.com SIP/2.0
      Via: SIP/2.0/UDP iftgw.example.com
      From: <sip:+13035551111@ift.client.example.net;user=phone>
      Record-Route: <sip:UserB@example.com;maddr=ss1.example.com>
      To: sip:+16505552222@ss1.example.net;user=phone
      Call-ID: 1717@ift.client.example.com
      CSeq: 56 INVITE
      Content-Type: application/sdp

      v=0
      o=mhandley 29739 7272939 IN IP4 192.0.2.5
      s=-
      c=IN IP4 192.0.2.5
      t=0 0
      m=audio 492170 RTP/AVP 0

4. Security Considerations

   This document presents NON NORMATIVE examples of SIP session
   establishment. The security considerations in [RFC3261] apply.

   Parsers must carefully consider edge conditions and malicious input
   as part of their design. Attacks on many Internet systems use crafted
   input to cause implementations to behave in undesirable ways. Many of
   the messages in this draft are designed to stress a parser
   implementation at points traditionally used for such attacks. This
   document does not, however, attempt to be comprehensive. It should be
   considered a seed to stimulate thinking and planning, not simply a
   set of tests to be passed.

5. Open Issues and Remaining Work

   1.  All of the messages in this document should be considered new.
       They are either new additions or major revisions of the previous
       versions. They all need to be carefully reviewed by the working
       group

   2.  Are the header field values in Section 3.1.1.7 long enough?
       Should we push each field over 256 octets or even longer? Where
       is the threshold of reason?

   3.  Is this really possible to recover from embedded whitespace in a
       SIP Request-URI as suggested in Section 3.1.2.8?

   4.  Can we modify the example in Section 3.1.2.15 such that it is not
       obvious where to infer quotes?

   5.  Can we modify the example in Section 3.1.2.13 such that it is not
       obvious (due to ambiguity perhaps) where to infer angle brackets?

   6.  Is the message at Section 3.3.11 sufficiently tortuous to include
       in this document?

6. Acknowledgments

   The authors wish to thank the following individuals for their
   participation in the review of earlier versions of this document:
   Aseem Agarwal, Rafi Assadi, Gonzalo Camarillo, Ben Campbell, Cullen
   Jennings, Vijay Gurbani, Sunitha Kumar, Rohan Mahy, Jon Peterson,
   Marc Petit-Huguenin, Vidhi Rastogi, Adam Roach, Bodgey Yin Shaohua
   and Tom Taylor.

   Thanks to Neil Deason for contributing several messages and Kundan
   Singh for performing parser validation of messages in earlier
   versions..

   The following individuals provided significant comments during the
   early phases of the development of this document: Jean-Francois Mule,
   Hemant Agrawal, Henry Sinnreich, David Devanatham, Joe Pizzimenti,
   Matt Cannon, John Hearty, the whole MCI WorldCom IPOP Design team,
   Scott Orton, Greg Osterhout, Pat Sollee, Doug Weisenberg, Danny
   Mistry, Steve McKinnon, and Denise Ingram, Denise Caballero, Tom
   Redman, Ilya Slain, Pat Sollee, John Truetken, and others from MCI
   WorldCom, 3Com, Cisco, Lucent and Nortel.

Informative References

   [RFC2396]  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
              Resource Identifiers (URI): Generic Syntax", RFC 2396,
              August 1998.

   [RFC2822]  Resnick, P., "Internet Message Format", RFC 2822, April
              2001.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M. and E. Schooler,
              "SIP: Session Initiation Protocol", RFC 3261, June 2002.

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264, June
              2002.

Authors' Addresses

   Robert J. Sparks (editor)
   dynamicsoft
   5100 Tennyson Parkway
   Suite 1200
   Plano, TX  75024

   EMail: rsparks@dynamicsoft.com

   Alan Hawrylyshen
   Jasomi Networks
   2033 Gateway Place
   Suite 500
   San Jose, CA  95110

   EMail: alan@jasomi.com

   Alan Johnston
   MCI
   100 South 4th Street
   St. Louis, MO  63102

   EMail: alan.johnston@mci.com
   Jonathan Rosenberg
   dynamicsoft
   600 Lanidex Plaza
   Parsippany, NJ  07052

   Phone: +1 973 952 5000
   EMail: jdrosen@dynamicsoft.com
   URI:   http://www.jdrosen.net

   Henning Schulzrinne
   Columbia University
   Department of Computer Science
   1214 Amsterdam Ave.
   New York, NY  10027
   USA

   EMail: schulzrinne@cs.columbia.edu

Appendix A. Bit-exact archive of each test message

   The following text block is an encoded, gzip compressed TAR archive
   of files that represent each of the example messages discussed in
   Section 3.

   To recover the compressed archive file intact, the text of this
   document may be passed as input to the following Perl script (the
   output should be redirected to a file or piped to "tar -xzvf -").

   #!/usr/bin/perl
   use strict;
   my $bdata = "";
   use MIME::Base64;
   while(<>) {
    if (/-- BEGIN MESSAGE ARCHIVE --/ .. /-- END MESSAGE ARCHIVE --/) {
        if ( m/^\s*[^\s]+\s*$/) {
            $bdata = $bdata . $_;
        }
     }
   }
   print decode_base64($bdata);

                               Figure 58

   Alternatively, the base-64 encoded block can be edited by hand to
   remove document structure lines and fed as input to any base-64
   decoding utility.

A.1 Encoded Reference Messages

   -- BEGIN MESSAGE ARCHIVE --
   H4sIAANxmD8CA+xdW4/bSHbumQF2Jx00MMD+AbqxWs/YTXWxqnhTt3raY/fs
   9PgyDbvtATYb2NViUaJEkWqSktwO4iTzsNm8BLPIY/IwCBIEecoGecgGCySA
   /MdSRd0okpLY7dbFHpat1oWHlyLr++qcU6dOnRGD+C1aKRok2FhQARIAioI3
   ACtq7J0XWVI3gKpiBahAgpDJI0WSNwSwsYTS9gPiCcKGV/dbxGv40+TmbX9H
   yzcnp8ffPHoi+Far1Papd0hfkmbLpkXXqwpPjk92YRFsbT6zSGn4bffpvROh
   5voBLg5lK26zJAMF7J15xKnUyq/02i/x2f2GUW9jBBHe2nxIXopful6XeIZf
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   -- END MESSAGE ARCHIVE --

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