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openbts/SIP/SIPBNF.txt
2014-03-25 00:06:30 +01:00

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25.1 Basic Rules
The following rules are used throughout this specification to
describe basic parsing constructs. The US-ASCII coded character set
is defined by ANSI X3.4-1986.
alphanum = ALPHA / DIGIT
Rosenberg, et. al. Standards Track [Page 219]
RFC 3261 SIP: Session Initiation Protocol June 2002
Several rules are incorporated from RFC 2396 [5] but are updated to
make them compliant with RFC 2234 [10]. These include:
reserved = ";" / "/" / "?" / ":" / "@" / "&" / "=" / "+"
/ "$" / ","
unreserved = alphanum / mark
mark = "-" / "_" / "." / "!" / "~" / "*" / "'"
/ "(" / ")"
escaped = "%" HEXDIG HEXDIG
SIP header field values can be folded onto multiple lines if the
continuation line begins with a space or horizontal tab. All linear
white space, including folding, has the same semantics as SP. A
recipient MAY replace any linear white space with a single SP before
interpreting the field value or forwarding the message downstream.
This is intended to behave exactly as HTTP/1.1 as described in RFC
2616 [8]. The SWS construct is used when linear white space is
optional, generally between tokens and separators.
LWS = [*WSP CRLF] 1*WSP ; linear whitespace
SWS = [LWS] ; sep whitespace
To separate the header name from the rest of value, a colon is used,
which, by the above rule, allows whitespace before, but no line
break, and whitespace after, including a linebreak. The HCOLON
defines this construct.
HCOLON = *( SP / HTAB ) ":" SWS
The TEXT-UTF8 rule is only used for descriptive field contents and
values that are not intended to be interpreted by the message parser.
Words of *TEXT-UTF8 contain characters from the UTF-8 charset (RFC
2279 [7]). The TEXT-UTF8-TRIM rule is used for descriptive field
contents that are n t quoted strings, where leading and trailing LWS
is not meaningful. In this regard, SIP differs from HTTP, which uses
the ISO 8859-1 character set.
TEXT-UTF8-TRIM = 1*TEXT-UTF8char *(*LWS TEXT-UTF8char)
TEXT-UTF8char = %x21-7E / UTF8-NONASCII
UTF8-NONASCII = %xC0-DF 1UTF8-CONT
/ %xE0-EF 2UTF8-CONT
/ %xF0-F7 3UTF8-CONT
/ %xF8-Fb 4UTF8-CONT
/ %xFC-FD 5UTF8-CONT
UTF8-CONT = %x80-BF
Rosenberg, et. al. Standards Track [Page 220]
RFC 3261 SIP: Session Initiation Protocol June 2002
A CRLF is allowed in the definition of TEXT-UTF8-TRIM only as part of
a header field continuation. It is expected that the folding LWS
will be replaced with a single SP before interpretation of the TEXT-
UTF8-TRIM value.
Hexadecimal numeric characters are used in several protocol elements.
Some elements (authentication) force hex alphas to be lower case.
LHEX = DIGIT / %x61-66 ;lowercase a-f
Many SIP header field values consist of words separated by LWS or
special characters. Unless otherwise stated, tokens are case-
insensitive. These special characters MUST be in a quoted string to
be used within a parameter value. The word construct is used in
Call-ID to allow most separators to be used.
token = 1*(alphanum / "-" / "." / "!" / "%" / "*"
/ "_" / "+" / "`" / "'" / "~" )
separators = "(" / ")" / "<" / ">" / "@" /
"," / ";" / ":" / "\" / DQUOTE /
"/" / "[" / "]" / "?" / "=" /
"{" / "}" / SP / HTAB
word = 1*(alphanum / "-" / "." / "!" / "%" / "*" /
"_" / "+" / "`" / "'" / "~" /
"(" / ")" / "<" / ">" /
":" / "\" / DQUOTE /
"/" / "[" / "]" / "?" /
"{" / "}" )
When tokens are used or separators are used between elements,
whitespace is often allowed before or after these characters:
STAR = SWS "*" SWS ; asterisk
SLASH = SWS "/" SWS ; slash
EQUAL = SWS "=" SWS ; equal
LPAREN = SWS "(" SWS ; left parenthesis
RPAREN = SWS ")" SWS ; right parenthesis
RAQUOT = ">" SWS ; right angle quote
LAQUOT = SWS "<"; left angle quote
COMMA = SWS "," SWS ; comma
SEMI = SWS ";" SWS ; semicolon
COLON = SWS ":" SWS ; colon
LDQUOT = SWS DQUOTE; open double quotation mark
RDQUOT = DQUOTE SWS ; close double quotation mark
Rosenberg, et. al. Standards Track [Page 221]
RFC 3261 SIP: Session Initiation Protocol June 2002
Comments can be included in some SIP header fields by surrounding the
comment text with parentheses. Comments are only allowed in fields
containing "comment" as part of their field value definition. In all
other fields, parentheses are considered part of the field value.
comment = LPAREN *(ctext / quoted-pair / comment) RPAREN
ctext = %x21-27 / %x2A-5B / %x5D-7E / UTF8-NONASCII
/ LWS
ctext includes all chars except left and right parens and backslash.
A string of text is parsed as a single word if it is quoted using
double-quote marks. In quoted strings, quotation marks (") and
backslashes (\) need to be escaped.
quoted-string = SWS DQUOTE *(qdtext / quoted-pair ) DQUOTE
qdtext = LWS / %x21 / %x23-5B / %x5D-7E
/ UTF8-NONASCII
The backslash character ("\") MAY be used as a single-character
quoting mechanism only within quoted-string and comment constructs.
Unlike HTTP/1.1, the characters CR and LF cannot be escaped by this
mechanism to avoid conflict with line folding and header separation.
quoted-pair = "\" (%x00-09 / %x0B-0C
/ %x0E-7F)
SIP-URI = "sip:" [ userinfo ] hostport
uri-parameters [ headers ]
SIPS-URI = "sips:" [ userinfo ] hostport
uri-parameters [ headers ]
userinfo = ( user / telephone-subscriber ) [ ":" password ] "@"
user = 1*( unreserved / escaped / user-unreserved )
user-unreserved = "&" / "=" / "+" / "$" / "," / ";" / "?" / "/"
password = *( unreserved / escaped /
"&" / "=" / "+" / "$" / "," )
hostport = host [ ":" port ]
host = hostname / IPv4address / IPv6reference
hostname = *( domainlabel "." ) toplabel [ "." ]
domainlabel = alphanum
/ alphanum *( alphanum / "-" ) alphanum
toplabel = ALPHA / ALPHA *( alphanum / "-" ) alphanum
Rosenberg, et. al. Standards Track [Page 222]
RFC 3261 SIP: Session Initiation Protocol June 2002
IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
IPv6reference = "[" IPv6address "]"
IPv6address = hexpart [ ":" IPv4address ]
hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ]
hexseq = hex4 *( ":" hex4)
hex4 = 1*4HEXDIG
port = 1*DIGIT
The BNF for telephone-subscriber can be found in RFC 2806 [9]. Note,
however, that any characters allowed there that are not allowed in
the user part of the SIP URI MUST be escaped.
uri-parameters = *( ";" uri-parameter)
uri-parameter = transport-param / user-param / method-param
/ ttl-param / maddr-param / lr-param / other-param
transport-param = "transport="
( "udp" / "tcp" / "sctp" / "tls"
/ other-transport)
other-transport = token
user-param = "user=" ( "phone" / "ip" / other-user)
other-user = token
method-param = "method=" Method
ttl-param = "ttl=" ttl
maddr-param = "maddr=" host
lr-param = "lr"
other-param = pname [ "=" pvalue ]
pname = 1*paramchar
pvalue = 1*paramchar
paramchar = param-unreserved / unreserved / escaped
param-unreserved = "[" / "]" / "/" / ":" / "&" / "+" / "$"
headers = "?" header *( "&" header )
header = hname "=" hvalue
hname = 1*( hnv-unreserved / unreserved / escaped )
hvalue = *( hnv-unreserved / unreserved / escaped )
hnv-unreserved = "[" / "]" / "/" / "?" / ":" / "+" / "$"
SIP-message = Request / Response
Request = Request-Line
*( message-header )
CRLF
[ message-body ]
Request-Line = Method SP Request-URI SP SIP-Version CRLF
Request-URI = SIP-URI / SIPS-URI / absoluteURI
absoluteURI = scheme ":" ( hier-part / opaque-part )
hier-part = ( net-path / abs-path ) [ "?" query ]
net-path = "//" authority [ abs-path ]
abs-path = "/" path-segments
Rosenberg, et. al. Standards Track [Page 223]
RFC 3261 SIP: Session Initiation Protocol June 2002
opaque-part = uric-no-slash *uric
uric = reserved / unreserved / escaped
uric-no-slash = unreserved / escaped / ";" / "?" / ":" / "@"
/ "&" / "=" / "+" / "$" / ","
path-segments = segment *( "/" segment )
segment = *pchar *( ";" param )
param = *pchar
pchar = unreserved / escaped /
":" / "@" / "&" / "=" / "+" / "$" / ","
scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
authority = srvr / reg-name
srvr = [ [ userinfo "@" ] hostport ]
reg-name = 1*( unreserved / escaped / "$" / ","
/ ";" / ":" / "@" / "&" / "=" / "+" )
query = *uric
SIP-Version = "SIP" "/" 1*DIGIT "." 1*DIGIT
message-header = (Accept
/ Accept-Encoding
/ Accept-Language
/ Alert-Info
/ Allow
/ Authentication-Info
/ Authorization
/ Call-ID
/ Call-Info
/ Contact
/ Content-Disposition
/ Content-Encoding
/ Content-Language
/ Content-Length
/ Content-Type
/ CSeq
/ Date
/ Error-Info
/ Expires
/ From
/ In-Reply-To
/ Max-Forwards
/ MIME-Version
/ Min-Expires
/ Organization
/ Priority
/ Proxy-Authenticate
/ Proxy-Authorization
/ Proxy-Require
/ Record-Route
/ Reply-To
Rosenberg, et. al. Standards Track [Page 224]
RFC 3261 SIP: Session Initiation Protocol June 2002
/ Require
/ Retry-After
/ Route
/ Server
/ Subject
/ Supported
/ Timestamp
/ To
/ Unsupported
/ User-Agent
/ Via
/ Warning
/ WWW-Authenticate
/ extension-header) CRLF
INVITEm = %x49.4E.56.49.54.45 ; INVITE in caps
ACKm = %x41.43.4B ; ACK in caps
OPTIONSm = %x4F.50.54.49.4F.4E.53 ; OPTIONS in caps
BYEm = %x42.59.45 ; BYE in caps
CANCELm = %x43.41.4E.43.45.4C ; CANCEL in caps
REGISTERm = %x52.45.47.49.53.54.45.52 ; REGISTER in caps
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
Status-Code = Informational
/ Redirection
/ Success
/ Client-Error
/ Server-Error
/ Global-Failure
/ extension-code
extension-code = 3DIGIT
Reason-Phrase = *(reserved / unreserved / escaped
/ UTF8-NONASCII / UTF8-CONT / SP / HTAB)
Informational = "100" ; Trying
/ "180" ; Ringing
/ "181" ; Call Is Being Forwarded
/ "182" ; Queued
/ "183" ; Session Progress
Rosenberg, et. al. Standards Track [Page 225]
RFC 3261 SIP: Session Initiation Protocol June 2002
Success = "200" ; OK
Redirection = "300" ; Multiple Choices
/ "301" ; Moved Permanently
/ "302" ; Moved Temporarily
/ "305" ; Use Proxy
/ "380" ; Alternative Service
Client-Error = "400" ; Bad Request
/ "401" ; Unauthorized
/ "402" ; Payment Required
/ "403" ; Forbidden
/ "404" ; Not Found
/ "405" ; Method Not Allowed
/ "406" ; Not Acceptable
/ "407" ; Proxy Authentication Required
/ "408" ; Request Timeout
/ "410" ; Gone
/ "413" ; Request Entity Too Large
/ "414" ; Request-URI Too Large
/ "415" ; Unsupported Media Type
/ "416" ; Unsupported URI Scheme
/ "420" ; Bad Extension
/ "421" ; Extension Required
/ "423" ; Interval Too Brief
/ "480" ; Temporarily not available
/ "481" ; Call Leg/Transaction Does Not Exist
/ "482" ; Loop Detected
/ "483" ; Too Many Hops
/ "484" ; Address Incomplete
/ "485" ; Ambiguous
/ "486" ; Busy Here
/ "487" ; Request Terminated
/ "488" ; Not Acceptable Here
/ "491" ; Request Pending
/ "493" ; Undecipherable
Server-Error = "500" ; Internal Server Error
/ "501" ; Not Implemented
/ "502" ; Bad Gateway
/ "503" ; Service Unavailable
/ "504" ; Server Time-out
/ "505" ; SIP Version not supported
/ "513" ; Message Too Large
Rosenberg, et. al. Standards Track [Page 226]
RFC 3261 SIP: Session Initiation Protocol June 2002
Global-Failure = "600" ; Busy Everywhere
/ "603" ; Decline
/ "604" ; Does not exist anywhere
/ "606" ; Not Acceptable
Accept = "Accept" HCOLON
[ accept-range *(COMMA accept-range) ]
accept-range = media-range *(SEMI accept-param)
media-range = ( "*/*"
/ ( m-type SLASH "*" )
/ ( m-type SLASH m-subtype )
) *( SEMI m-parameter )
accept-param = ("q" EQUAL qvalue) / generic-param
qvalue = ( "0" [ "." 0*3DIGIT ] )
/ ( "1" [ "." 0*3("0") ] )
generic-param = token [ EQUAL gen-value ]
gen-value = token / host / quoted-string
Accept-Encoding = "Accept-Encoding" HCOLON
[ encoding *(COMMA encoding) ]
encoding = codings *(SEMI accept-param)
codings = content-coding / "*"
content-coding = token
Accept-Language = "Accept-Language" HCOLON
[ language *(COMMA language) ]
language = language-range *(SEMI accept-param)
language-range = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) / "*" )
Alert-Info = "Alert-Info" HCOLON alert-param *(COMMA alert-param)
alert-param = LAQUOT absoluteURI RAQUOT *( SEMI generic-param )
Allow = "Allow" HCOLON [Method *(COMMA Method)]
Authorization = "Authorization" HCOLON credentials
credentials = ("Digest" LWS digest-response)
/ other-response
digest-response = dig-resp *(COMMA dig-resp)
dig-resp = username / realm / nonce / digest-uri
/ dresponse / algorithm / cnonce
/ opaque / message-qop
/ nonce-count / auth-param
username = "username" EQUAL username-value
username-value = quoted-string
digest-uri = "uri" EQUAL LDQUOT digest-uri-value RDQUOT
digest-uri-value = rquest-uri ; Equal to request-uri as specified
by HTTP/1.1
message-qop = "qop" EQUAL qop-value
Rosenberg, et. al. Standards Track [Page 227]
RFC 3261 SIP: Session Initiation Protocol June 2002
cnonce = "cnonce" EQUAL cnonce-value
cnonce-value = nonce-value
nonce-count = "nc" EQUAL nc-value
nc-value = 8LHEX
dresponse = "response" EQUAL request-digest
request-digest = LDQUOT 32LHEX RDQUOT
auth-param = auth-param-name EQUAL
( token / quoted-string )
auth-param-name = token
other-response = auth-scheme LWS auth-param
*(COMMA auth-param)
auth-scheme = token
Authentication-Info = "Authentication-Info" HCOLON ainfo
*(COMMA ainfo)
ainfo = nextnonce / message-qop
/ response-auth / cnonce
/ nonce-count
nextnonce = "nextnonce" EQUAL nonce-value
response-auth = "rspauth" EQUAL response-digest
response-digest = LDQUOT *LHEX RDQUOT
Call-ID = ( "Call-ID" / "i" ) HCOLON callid
callid = word [ "@" word ]
Call-Info = "Call-Info" HCOLON info *(COMMA info)
info = LAQUOT absoluteURI RAQUOT *( SEMI info-param)
info-param = ( "purpose" EQUAL ( "icon" / "info"
/ "card" / token ) ) / generic-param
Contact = ("Contact" / "m" ) HCOLON
( STAR / (contact-param *(COMMA contact-param)))
contact-param = (name-addr / addr-spec) *(SEMI contact-params)
name-addr = [ display-name ] LAQUOT addr-spec RAQUOT
addr-spec = SIP-URI / SIPS-URI / absoluteURI
display-name = *(token LWS)/ quoted-string
contact-params = c-p-q / c-p-expires
/ contact-extension
c-p-q = "q" EQUAL qvalue
c-p-expires = "expires" EQUAL delta-seconds
contact-extension = generic-param
delta-seconds = 1*DIGIT
Content-Disposition = "Content-Disposition" HCOLON
disp-type *( SEMI disp-param )
disp-type = "render" / "session" / "icon" / "alert"
/ disp-extension-token
Rosenberg, et. al. Standards Track [Page 228]
RFC 3261 SIP: Session Initiation Protocol June 2002
disp-param = handling-param / generic-param
handling-param = "handling" EQUAL
( "optional" / "required"
/ other-handling )
other-handling = token
disp-extension-token = token
Content-Encoding = ( "Content-Encoding" / "e" ) HCOLON
content-coding *(COMMA content-coding)
Content-Language = "Content-Language" HCOLON
language-tag *(COMMA language-tag)
language-tag = primary-tag *( "-" subtag )
primary-tag = 1*8ALPHA
subtag = 1*8ALPHA
Content-Length = ( "Content-Length" / "l" ) HCOLON 1*DIGIT
Content-Type = ( "Content-Type" / "c" ) HCOLON media-type
media-type = m-type SLASH m-subtype *(SEMI m-parameter)
m-type = discrete-type / composite-type
discrete-type = "text" / "image" / "audio" / "video"
/ "application" / extension-token
composite-type = "message" / "multipart" / extension-token
extension-token = ietf-token / x-token
ietf-token = token
x-token = "x-" token
m-subtype = extension-token / iana-token
iana-token = token
m-parameter = m-attribute EQUAL m-value
m-attribute = token
m-value = token / quoted-string
CSeq = "CSeq" HCOLON 1*DIGIT LWS Method
Date = "Date" HCOLON SIP-date
SIP-date = rfc1123-date
rfc1123-date = wkday "," SP date1 SP time SP "GMT"
date1 = 2DIGIT SP month SP 4DIGIT
; day month year (e.g., 02 Jun 1982)
time = 2DIGIT ":" 2DIGIT ":" 2DIGIT
; 00:00:00 - 23:59:59
wkday = "Mon" / "Tue" / "Wed"
/ "Thu" / "Fri" / "Sat" / "Sun"
month = "Jan" / "Feb" / "Mar" / "Apr"
/ "May" / "Jun" / "Jul" / "Aug"
/ "Sep" / "Oct" / "Nov" / "Dec"
Error-Info = "Error-Info" HCOLON error-uri *(COMMA error-uri)
Rosenberg, et. al. Standards Track [Page 229]
RFC 3261 SIP: Session Initiation Protocol June 2002
error-uri = LAQUOT absoluteURI RAQUOT *( SEMI generic-param )
Expires = "Expires" HCOLON delta-seconds
From = ( "From" / "f" ) HCOLON from-spec
from-spec = ( name-addr / addr-spec )
*( SEMI from-param )
from-param = tag-param / generic-param
tag-param = "tag" EQUAL token
In-Reply-To = "In-Reply-To" HCOLON callid *(COMMA callid)
Max-Forwards = "Max-Forwards" HCOLON 1*DIGIT
MIME-Version = "MIME-Version" HCOLON 1*DIGIT "." 1*DIGIT
Min-Expires = "Min-Expires" HCOLON delta-seconds
Organization = "Organization" HCOLON [TEXT-UTF8-TRIM]
Priority = "Priority" HCOLON priority-value
priority-value = "emergency" / "urgent" / "normal"
/ "non-urgent" / other-priority
other-priority = token
Proxy-Authenticate = "Proxy-Authenticate" HCOLON challenge
challenge = ("Digest" LWS digest-cln *(COMMA digest-cln))
/ other-challenge
other-challenge = auth-scheme LWS auth-param
*(COMMA auth-param)
digest-cln = realm / domain / nonce
/ opaque / stale / algorithm
/ qop-options / auth-param
realm = "realm" EQUAL realm-value
realm-value = quoted-string
domain = "domain" EQUAL LDQUOT URI
*( 1*SP URI ) RDQUOT
URI = absoluteURI / abs-path
nonce = "nonce" EQUAL nonce-value
nonce-value = quoted-string
opaque = "opaque" EQUAL quoted-string
stale = "stale" EQUAL ( "true" / "false" )
algorithm = "algorithm" EQUAL ( "MD5" / "MD5-sess"
/ token )
qop-options = "qop" EQUAL LDQUOT qop-value
*("," qop-value) RDQUOT
qop-value = "auth" / "auth-int" / token
Proxy-Authorization = "Proxy-Authorization" HCOLON credentials
Rosenberg, et. al. Standards Track [Page 230]
RFC 3261 SIP: Session Initiation Protocol June 2002
Proxy-Require = "Proxy-Require" HCOLON option-tag
*(COMMA option-tag)
option-tag = token
Record-Route = "Record-Route" HCOLON rec-route *(COMMA rec-route)
rec-route = name-addr *( SEMI rr-param )
rr-param = generic-param
Reply-To = "Reply-To" HCOLON rplyto-spec
rplyto-spec = ( name-addr / addr-spec )
*( SEMI rplyto-param )
rplyto-param = generic-param
Require = "Require" HCOLON option-tag *(COMMA option-tag)
Retry-After = "Retry-After" HCOLON delta-seconds
[ comment ] *( SEMI retry-param )
retry-param = ("duration" EQUAL delta-seconds)
/ generic-param
Route = "Route" HCOLON route-param *(COMMA route-param)
route-param = name-addr *( SEMI rr-param )
Server = "Server" HCOLON server-val *(LWS server-val)
server-val = product / comment
product = token [SLASH product-version]
product-version = token
Subject = ( "Subject" / "s" ) HCOLON [TEXT-UTF8-TRIM]
Supported = ( "Supported" / "k" ) HCOLON
[option-tag *(COMMA option-tag)]
Timestamp = "Timestamp" HCOLON 1*(DIGIT)
[ "." *(DIGIT) ] [ LWS delay ]
delay = *(DIGIT) [ "." *(DIGIT) ]
To = ( "To" / "t" ) HCOLON ( name-addr
/ addr-spec ) *( SEMI to-param )
to-param = tag-param / generic-param
Unsupported = "Unsupported" HCOLON option-tag *(COMMA option-tag)
User-Agent = "User-Agent" HCOLON server-val *(LWS server-val)
Rosenberg, et. al. Standards Track [Page 231]
RFC 3261 SIP: Session Initiation Protocol June 2002
Via = ( "Via" / "v" ) HCOLON via-parm *(COMMA via-parm)
via-parm = sent-protocol LWS sent-by *( SEMI via-params )
via-params = via-ttl / via-maddr
/ via-received / via-branch
/ via-extension
via-ttl = "ttl" EQUAL ttl
via-maddr = "maddr" EQUAL host
via-received = "received" EQUAL (IPv4address / IPv6address)
via-branch = "branch" EQUAL token
via-extension = generic-param
sent-protocol = protocol-name SLASH protocol-version
SLASH transport
protocol-name = "SIP" / token
protocol-version = token
transport = "UDP" / "TCP" / "TLS" / "SCTP"
/ other-transport
sent-by = host [ COLON port ]
ttl = 1*3DIGIT ; 0 to 255
Warning = "Warning" HCOLON warning-value *(COMMA warning-value)
warning-value = warn-code SP warn-agent SP warn-text
warn-code = 3DIGIT
warn-agent = hostport / pseudonym
; the name or pseudonym of the server adding
; the Warning header, for use in debugging
warn-text = quoted-string
pseudonym = token
WWW-Authenticate = "WWW-Authenticate" HCOLON challenge
extension-header = header-name HCOLON header-value
header-name = token
header-value = *(TEXT-UTF8char / UTF8-CONT / LWS)
message-body = *OCTET