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560 lines
17 KiB
560 lines
17 KiB
// -*-go-*-
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//
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// Ragel SIP Message Parser
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//
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// This file is compiled into Go code by the Ragel State Machine Compiler for
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// the purpose of converting SIP messages into a Msg data structure. This
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// machine works in tandem with the Ragel machine defined in uri_parse.rl.
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//
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// Perhaps it would have been better if the authors of this protocol had chosen
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// to use a binary serialization format like protocol buffers. But instead they
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// chose to create a plaintext protocol that looks similar to HTTP requests,
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// but are phenomenally more complicated.
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//
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// SIP messages are quite insane.
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//
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// o Whitespace can be used liberally in a variety of different ways.
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//
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// - Via host:port can have whitespace, e.g. "host \t: port"
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//
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// o UTF-8 is supported in some places but not others.
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//
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// o Headers can span multiple lines.
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//
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// o Header values can contain comments, e.g. Message: lol (i'm (hidden))
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//
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// o Header names are case-insensitive and have shorthand notation.
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//
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// o There's ~50 standard headers, many of which have custom parsing rules.
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//
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// o URIs can have ;params;like=this
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//
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// - Params can belong either to a URI or Addr object, e.g. <sip:uri;param>
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// cf. <sip:uri>;param
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//
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// - Addresses may omit angle brackets, in which case params belong to the
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// Addr object.
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//
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// - URI params ;are=escaped%20like%22this but params belonging to Addr
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// ;are="escaped like\"this"
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//
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// - Backslash escaping is not like C, e.g. \t\n -> tn
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//
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// - Address display name can have whitespace without quotes, which is
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// collapsed. Quoted form is not collapsed.
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//
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// o Via and address headers can be repeated in two ways: repeating the
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// header, using commas within a single header, or both.
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//
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// See: http://www.colm.net/files/ragel/ragel-guide-6.9.pdf
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// See: http://zedshaw.com/archive/ragel-state-charts/
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package sip
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import (
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"errors"
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"fmt"
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"github.com/jart/gosip/sdp"
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)
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%% machine msg;
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%% write data;
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// ParseMsg turns a SIP message into a data structure.
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func ParseMsg(s string) (msg *Msg, err error) {
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if s == "" {
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return nil, errors.New("Empty SIP message")
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}
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return ParseMsgBytes([]byte(s))
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}
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// ParseMsg turns a SIP message byte slice into a data structure.
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func ParseMsgBytes(data []byte) (msg *Msg, err error) {
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if data == nil {
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return nil, nil
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}
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msg = new(Msg)
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viap := &msg.Via
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cs := 0
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p := 0
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pe := len(data)
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eof := len(data)
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line := 1
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linep := 0
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buf := make([]byte, len(data))
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amt := 0
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mark := 0
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clen := 0
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ctype := ""
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var name string
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var hex byte
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var value *string
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var addr **Addr
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var via *Via
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%%{
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action hold {
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fhold;
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}
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action break {
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fbreak;
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}
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action line {
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line++
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linep = p + 1
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}
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action mark {
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mark = p
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}
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action start {
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amt = 0
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}
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action append {
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buf[amt] = fc
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amt++
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}
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action space {
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buf[amt] = ' '
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amt++
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}
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action collapse {
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amt = appendCollapse(buf, amt, fc)
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}
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action hexHi {
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hex = unhex(fc) * 16
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}
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action hexLo {
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hex += unhex(fc)
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buf[amt] = hex
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amt++
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}
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action lower {
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amt = appendLower(buf, amt, fc)
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}
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action Method {
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msg.Method = string(data[mark:p])
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}
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action VersionMajor {
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msg.VersionMajor = msg.VersionMajor * 10 + (fc - 0x30)
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}
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action VersionMinor {
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msg.VersionMinor = msg.VersionMinor * 10 + (fc - 0x30)
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}
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action RequestURI {
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msg.Request, err = ParseURIBytes(data[mark:p])
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if err != nil { return nil, err }
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}
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action StatusCode {
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msg.Status = msg.Status * 10 + (int(fc) - 0x30)
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}
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action ReasonPhrase {
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msg.Phrase = string(buf[0:amt])
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}
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action Via {
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*viap = via
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viap = &via.Next
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// via = nil
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}
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action ViaProtocol {
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via.Protocol = string(data[mark:p])
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}
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action ViaVersion {
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via.Version = string(data[mark:p])
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}
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action ViaTransport {
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via.Transport = string(data[mark:p])
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}
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action ViaHost {
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via.Host = string(data[mark:p])
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}
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action ViaPort {
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via.Port = via.Port * 10 + (uint16(fc) - 0x30)
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}
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action ViaParam {
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if via.Params == nil {
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via.Params = Params{}
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}
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via.Params[name] = string(buf[0:amt])
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}
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action goto_header {
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fgoto header;
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}
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action goto_value {
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fgoto value;
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}
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action goto_via {
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via = new(Via)
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fgoto via;
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}
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action goto_via_param {
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amt = 0 // Needed so ViaParam action works when there's no value.
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fgoto via_param;
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}
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action gxh {
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fhold;
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fgoto xheader;
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}
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action name {
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name = string(data[mark:p])
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}
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action value {{
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b := data[mark:p - 1]
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if value != nil {
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*value = string(b)
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} else if addr != nil {
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*addr, err = ParseAddrBytes(b, *addr)
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if err != nil { return nil, err }
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} else {
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if msg.Headers == nil {
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msg.Headers = Headers{}
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}
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msg.Headers[name] = string(b)
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}
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}}
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action new_addr {
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addr = new(Addr)
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}
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action addr_display {
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addr.Display = strings.TrimRight(string(buf[0:amt]), " \t\r\n")
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}
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action addr_uri {
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addr.Uri, err = ParseURIBytes(data[mark:p])
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if err != nil { return nil, err }
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}
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action addr_param {
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if addr.Params == nil {
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addr.Params = Params{}
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}
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addr.Params[name] = string(buf[0:amt])
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}
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action CallID {
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msg.CallID = string(data[mark:p])
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}
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action ContentLength {
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clen = clen * 10 + (int(fc) - 0x30)
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}
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action ContentType {
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ctype = string(data[mark:p])
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}
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action CSeq {
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msg.CSeq = msg.CSeq * 10 + (int(fc) - 0x30)
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}
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action CSeqMethod {
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msg.CSeqMethod = string(data[mark:p])
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}
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action Expires {
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msg.Expires = msg.Expires * 10 + (int(fc) - 0x30)
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}
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action MaxForwards {
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msg.MaxForwards = msg.MaxForwards * 10 + (int(fc) - 0x30)
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}
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action MinExpires {
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msg.MinExpires = msg.MinExpires * 10 + (int(fc) - 0x30)
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}
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action lookAheadWSP { lookAheadWSP(data, p, pe) }
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# https://tools.ietf.org/html/rfc2234
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SP = " ";
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HTAB = "\t";
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CR = "\r";
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LF = "\n" @line;
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DQUOTE = "\"";
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CRLF = CR LF;
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WSP = SP | HTAB;
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LWS = ( WSP* ( CR when lookAheadWSP ) LF )? WSP+;
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SWS = LWS?;
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LWSCRLF_append = ( CR when lookAheadWSP ) @append LF @append;
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LWS_append = ( WSP* @append LWSCRLF_append )? WSP+ @append;
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UTF8_CONT = 0x80..0xBF @append;
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UTF8_NONASCII = 0xC0..0xDF @append UTF8_CONT {1}
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| 0xE0..0xEF @append UTF8_CONT {2}
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| 0xF0..0xF7 @append UTF8_CONT {3}
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| 0xF8..0xFb @append UTF8_CONT {4}
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| 0xFC..0xFD @append UTF8_CONT {5};
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UTF8 = 0x21..0x7F @append | UTF8_NONASCII;
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mUTF8_CONT = 0x80..0xBF;
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mUTF8_NONASCII = 0xC0..0xDF mUTF8_CONT {1}
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| 0xE0..0xEF mUTF8_CONT {2}
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| 0xF0..0xF7 mUTF8_CONT {3}
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| 0xF8..0xFb mUTF8_CONT {4}
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| 0xFC..0xFD mUTF8_CONT {5};
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mUTF8 = 0x21..0x7F | mUTF8_NONASCII;
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# https://tools.ietf.org/html/rfc3261#section-25.1
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reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" | "$" | "," ;
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mark = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")" ;
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unreserved = alnum | mark ;
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tokenc = alnum | "-" | "." | "!" | "%" | "*" | "_" | "+" | "`"
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| "'" | "~" ;
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separators = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\\"
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| "\"" | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP
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| HTAB ;
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wordc = alnum | "-" | "." | "!" | "%" | "*" | "_" | "+" | "`"
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| "'" | "~" | "(" | ")" | "<" | ">" | ":" | "\\" | "\""
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| "/" | "[" | "]" | "?" | "{" | "}" ;
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schmchars = alnum | "+" | "-" | "." ;
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word = wordc+;
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STAR = SWS "*" SWS;
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SLASH = SWS "/" SWS;
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EQUAL = SWS "=" SWS;
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LPAREN = SWS "(" SWS;
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RPAREN = SWS ")" SWS;
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RAQUOT = ">" SWS;
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LAQUOT = SWS "<";
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COMMA = SWS "," SWS;
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SEMI = SWS ";" SWS;
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COLON = SWS ":" SWS;
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HCOLON = WSP* ":" SWS;
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LDQUOT = SWS "\"";
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RDQUOT = "\"" SWS;
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escaped = "%" ( xdigit @hexHi ) ( xdigit @hexLo ) ;
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ipv4 = digit | "." ;
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ipv6 = xdigit | "." | ":" ;
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hostname = alpha | digit | "-" | "." ;
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uric = reserved | unreserved | "%" | "[" | "]";
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uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" | "&" | "="
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| "+" | "$" | "," ;
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uri = alpha schmchars* ":" uric+;
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token = tokenc+;
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tokenhost = ( tokenc | "[" | "]" | ":" )+;
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reasonc = UTF8_NONASCII | ( reserved | unreserved | SP | HTAB ) @append;
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reasonmc = escaped | reasonc;
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cid = word ( "@" word )?;
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Method = token >mark %Method;
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SIPVersionNo = digit+ @VersionMajor "." digit+ @VersionMinor;
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RequestURI = ^SP+ >mark %RequestURI;
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StatusCode = ( digit @StatusCode ) {3};
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ReasonPhrase = reasonmc+ >start %ReasonPhrase;
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hval = ( mUTF8 | LWS )* >mark;
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# Quoted strings can have just about anything, including backslash escapes,
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# which aren't quite as fancy as the ones you'd see in programming.
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qdtextc = 0x21 | 0x23..0x5B | 0x5D..0x7E;
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qdtext = UTF8_NONASCII | LWS_append | qdtextc @append;
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quoted_pair = "\\" ( 0x00..0x09 | 0x0B..0x0C | 0x0E..0x7F ) @append;
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quoted_content = ( qdtext | quoted_pair )* >start;
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quoted_string = SWS DQUOTE quoted_content DQUOTE;
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# Via Parsing
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#
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# Parsing these is kind of difficult because infinite whitespace is allowed
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# between colons, semicolons, commas, and don't forget that lines can
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# continue. So we're going to break things down into four separate machines
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# that jump between each other.
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ViaProtocol = token >mark %ViaProtocol;
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ViaVersion = token >mark %ViaVersion;
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ViaTransport = token >mark %ViaTransport;
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ViaSent = ViaProtocol SLASH ViaVersion SLASH ViaTransport;
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ViaHostIPv4 = ( digit | "." )+ >mark %ViaHost;
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ViaHostIPv6 = "[" ( xdigit | "." | ":" )+ >mark %ViaHost "]";
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ViaHostName = ( alnum | "." | "-" )+ >mark %ViaHost;
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ViaHost = ViaHostIPv4 | ViaHostIPv6 | ViaHostName;
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ViaPort = digit+ @ViaPort;
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ViaParamName = token >mark %name;
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ViaParamContent = tokenhost >start @append;
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ViaParamValue = ViaParamContent | quoted_string;
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via_param_end = CRLF @ViaParam @Via @goto_header
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| SEMI <: any @hold @ViaParam @goto_via_param
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| COMMA <: any @hold @ViaParam @Via @goto_via;
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via_param := ViaParamName (EQUAL ViaParamValue)? via_param_end;
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via_end = CRLF @Via @goto_header
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| SEMI <: any @hold @goto_via_param
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| COMMA <: any @hold @Via @goto_via;
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via := ViaSent LWS ViaHost (COLON ViaPort)? via_end;
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# Address Header Name Definitions
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#
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# These headers set the addr pointer to tell the 'value' machine where to
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# store the value after using ParseAddrBytes().
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aname = ("Contact"i | "m"i) %{addr=&msg.Contact}
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| ("From"i | "f"i) %{addr=&msg.From}
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| "P-Asserted-Identity"i %{addr=&msg.PAssertedIdentity}
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| "Record-Route"i %{addr=&msg.RecordRoute}
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| "Remote-Party-ID"i %{addr=&msg.RemotePartyID}
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| "Route"i %{addr=&msg.Route}
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| ("To"i | "t"i) %{addr=&msg.To}
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;
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# String Header Name Definitions
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#
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# These headers set the value pointer to tell the 'value' machine where to
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# store the resulting token string.
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sname = "Accept"i %{value=&msg.Accept}
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| ("Accept-Contact"i | "a"i) %{value=&msg.AcceptContact}
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| "Accept-Encoding"i %{value=&msg.AcceptEncoding}
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| "Accept-Language"i %{value=&msg.AcceptLanguage}
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| ("Allow"i | "u"i) %{value=&msg.Allow}
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| ("Allow-Events"i | "u"i) %{value=&msg.AllowEvents}
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| "Alert-Info"i %{value=&msg.AlertInfo}
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| "Authentication-Info"i %{value=&msg.AuthenticationInfo}
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| "Authorization"i %{value=&msg.Authorization}
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| "Content-Disposition"i %{value=&msg.ContentDisposition}
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| "Content-Language"i %{value=&msg.ContentLanguage}
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| ("Content-Encoding"i | "e"i) %{value=&msg.ContentEncoding}
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| "Call-Info"i %{value=&msg.CallInfo}
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| "Date"i %{value=&msg.Date}
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| "Error-Info"i %{value=&msg.ErrorInfo}
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| ("Event"i | "o"i) %{value=&msg.Event}
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| "In-Reply-To"i %{value=&msg.InReplyTo}
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| "Reply-To"i %{value=&msg.ReplyTo}
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| "MIME-Version"i %{value=&msg.MIMEVersion}
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| "Organization"i %{value=&msg.Organization}
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| "Priority"i %{value=&msg.Priority}
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| "Proxy-Authenticate"i %{value=&msg.ProxyAuthenticate}
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| "Proxy-Authorization"i %{value=&msg.ProxyAuthorization}
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| "Proxy-Require"i %{value=&msg.ProxyRequire}
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| ("Refer-To"i | "r"i) %{value=&msg.ReferTo}
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| ("Referred-By"i | "b"i) %{value=&msg.ReferredBy}
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| "Require"i %{value=&msg.Require}
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| "Retry-After"i %{value=&msg.RetryAfter}
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| "Server"i %{value=&msg.Server}
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| ("Subject"i | "s"i) %{value=&msg.Subject}
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| ("Supported"i | "k"i) %{value=&msg.Supported}
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| "Timestamp"i %{value=&msg.Timestamp}
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| "Unsupported"i %{value=&msg.Unsupported}
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| "User-Agent"i %{value=&msg.UserAgent}
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| "Warning"i %{value=&msg.Warning}
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| "WWW-Authenticate"i %{value=&msg.WWWAuthenticate}
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;
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# Custom Header Definitions
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#
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# These headers do not jump to the 'value' machine, but instead specify
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# their own special type of parsing.
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cheader = ("Call-ID"i | "i"i) $!gxh HCOLON cid >mark %CallID
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| ("Content-Length"i | "l"i) $!gxh HCOLON digit+ >{clen=0} @ContentLength
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| ("Content-Type"i | "c"i) $!gxh HCOLON <: hval %ContentType
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| "CSeq"i $!gxh HCOLON (digit+ @CSeq) LWS token >mark %CSeqMethod
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| ("Expires"i | "l"i) $!gxh HCOLON digit+ >{msg.Expires=0} @Expires
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| ("Max-Forwards"i | "l"i) $!gxh HCOLON digit+ >{msg.MaxForwards=0} @MaxForwards
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| ("Min-Expires"i | "l"i) $!gxh HCOLON digit+ >{msg.MinExpires=0} @MinExpires
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;
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# Header Parsing
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#
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# The header machine parses a single header and then jumps to itself to
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# loop. When the final CRLF is observed, we then break out of the Ragel
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# parser and let the Go code handle payload extraction.
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#
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# Parsing standard header names is a prefix trie search in generated code.
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# Lookahead to set the mark on the header name. In order to support
|
|
# extended headers, we'll use $!gxh to jump to the xheader machine when an
|
|
# unrecognized character is detected in the header name.
|
|
#
|
|
# An independent machine has been created for generic header values, so
|
|
# that it doesn't need to be duplicated for each leaf in the prefix
|
|
# trie. When the value machine has finished reading a value, it'll be
|
|
# parsed and stored based on whether the value/addr pointers are set.
|
|
#
|
|
# Header values can span multiple lines. Lookahead is used in the LWS
|
|
# definition to check for whitespace at the start of the next line upon
|
|
# encountering a line feed character, in order to determine if a line
|
|
# continuation is present.
|
|
#
|
|
# In order to concatenate across machines, we use lookahead in conjunction
|
|
# with the left-guarded concatenation operator. This pattern works is
|
|
# defined as follows: `foo <: any @hold @goto_bar`.
|
|
#
|
|
# Header names are case insensitive. Each recognized header is assigned to
|
|
# a specific field in the Msg data structure. Extended headers are stored
|
|
# to a linked list data structure with the casing preserved. This is so
|
|
# messages can be reproduced with roughly the same appearance. It is the
|
|
# responsibility of the person using Msg.Headers to do case-insensitive
|
|
# string comparisons.
|
|
value := hval <: CRLF @value @goto_header;
|
|
xheader := token %name HCOLON <: any @{value=nil;addr=nil} @hold @goto_value;
|
|
sheader = cheader <: CRLF @goto_header
|
|
| aname $!gxh HCOLON <: any @{value=nil} @hold @goto_value
|
|
| sname $!gxh HCOLON <: any @{addr=nil} @hold @goto_value
|
|
| ("Via"i | "v"i) $!gxh HCOLON <: any @hold @goto_via;
|
|
header := CRLF @break
|
|
| tokenc @mark @hold sheader;
|
|
|
|
# Start Line Parsing
|
|
#
|
|
# The Request and Response definitions are very straightforward, and the
|
|
# main machine is the union of the two. Once the line feed character has
|
|
# been observed, we then jump to the header machine.
|
|
SIPVersion = "SIP/" SIPVersionNo;
|
|
Request = Method SP RequestURI SP SIPVersion CRLF @goto_header;
|
|
Response = SIPVersion SP StatusCode SP ReasonPhrase CRLF @goto_header;
|
|
main := Request | Response;
|
|
|
|
write init;
|
|
write exec;
|
|
}%%
|
|
|
|
if cs < msg_first_final {
|
|
if p == pe {
|
|
return nil, errors.New(fmt.Sprintf("Incomplete SIP message: %s", data))
|
|
} else {
|
|
return nil, errors.New(fmt.Sprintf("Error in SIP message at line %d offset %d:\n%s", line, p - linep, data))
|
|
}
|
|
}
|
|
|
|
if clen > 0 {
|
|
if clen != len(data) - p {
|
|
return nil, errors.New(fmt.Sprintf("Content-Length incorrect: %d != %d", clen, len(data) - p))
|
|
}
|
|
if ctype == sdp.ContentType {
|
|
ms, err := sdp.Parse(string(data[p:len(data)]))
|
|
if err != nil { return nil, err }
|
|
msg.Payload = ms
|
|
} else {
|
|
msg.Payload = &MiscPayload{T: ctype, D: data[p:len(data)]}
|
|
}
|
|
}
|
|
|
|
return msg, nil
|
|
}
|
|
|
|
func lookAheadWSP(data []byte, p, pe int) bool {
|
|
return p + 2 < pe && (data[p+2] == ' ' || data[p+2] == '\t')
|
|
}
|