grammar

Sofia SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification.

 *    Accept         =  "Accept" HCOLON
 *                       [ accept-range *(COMMA accept-range) ]
 *    accept-range   =  media-range *(SEMI accept-param)
 *    ; Why not SLASH ? //PPe
 *    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
 *    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
 *    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)
 *    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
 * 
 *    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)
 * 
 *    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
 */