blob: 540368811e96735e3f510131a31652ea4b7e24db [file] [log] [blame]
// Copyright 2017 Google, Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.
package layers
import (
"bytes"
"fmt"
"io"
"strconv"
"strings"
"github.com/google/gopacket"
)
// SIPVersion defines the different versions of the SIP Protocol
type SIPVersion uint8
// Represents all the versions of SIP protocol
const (
SIPVersion1 SIPVersion = 1
SIPVersion2 SIPVersion = 2
)
func (sv SIPVersion) String() string {
switch sv {
default:
// Defaulting to SIP/2.0
return "SIP/2.0"
case SIPVersion1:
return "SIP/1.0"
case SIPVersion2:
return "SIP/2.0"
}
}
// GetSIPVersion is used to get SIP version constant
func GetSIPVersion(version string) (SIPVersion, error) {
switch strings.ToUpper(version) {
case "SIP/1.0":
return SIPVersion1, nil
case "SIP/2.0":
return SIPVersion2, nil
default:
return 0, fmt.Errorf("Unknown SIP version: '%s'", version)
}
}
// SIPMethod defines the different methods of the SIP Protocol
// defined in the different RFC's
type SIPMethod uint16
// Here are all the SIP methods
const (
SIPMethodInvite SIPMethod = 1 // INVITE [RFC3261]
SIPMethodAck SIPMethod = 2 // ACK [RFC3261]
SIPMethodBye SIPMethod = 3 // BYE [RFC3261]
SIPMethodCancel SIPMethod = 4 // CANCEL [RFC3261]
SIPMethodOptions SIPMethod = 5 // OPTIONS [RFC3261]
SIPMethodRegister SIPMethod = 6 // REGISTER [RFC3261]
SIPMethodPrack SIPMethod = 7 // PRACK [RFC3262]
SIPMethodSubscribe SIPMethod = 8 // SUBSCRIBE [RFC6665]
SIPMethodNotify SIPMethod = 9 // NOTIFY [RFC6665]
SIPMethodPublish SIPMethod = 10 // PUBLISH [RFC3903]
SIPMethodInfo SIPMethod = 11 // INFO [RFC6086]
SIPMethodRefer SIPMethod = 12 // REFER [RFC3515]
SIPMethodMessage SIPMethod = 13 // MESSAGE [RFC3428]
SIPMethodUpdate SIPMethod = 14 // UPDATE [RFC3311]
SIPMethodPing SIPMethod = 15 // PING [https://tools.ietf.org/html/draft-fwmiller-ping-03]
)
func (sm SIPMethod) String() string {
switch sm {
default:
return "Unknown method"
case SIPMethodInvite:
return "INVITE"
case SIPMethodAck:
return "ACK"
case SIPMethodBye:
return "BYE"
case SIPMethodCancel:
return "CANCEL"
case SIPMethodOptions:
return "OPTIONS"
case SIPMethodRegister:
return "REGISTER"
case SIPMethodPrack:
return "PRACK"
case SIPMethodSubscribe:
return "SUBSCRIBE"
case SIPMethodNotify:
return "NOTIFY"
case SIPMethodPublish:
return "PUBLISH"
case SIPMethodInfo:
return "INFO"
case SIPMethodRefer:
return "REFER"
case SIPMethodMessage:
return "MESSAGE"
case SIPMethodUpdate:
return "UPDATE"
case SIPMethodPing:
return "PING"
}
}
// GetSIPMethod returns the constant of a SIP method
// from its string
func GetSIPMethod(method string) (SIPMethod, error) {
switch strings.ToUpper(method) {
case "INVITE":
return SIPMethodInvite, nil
case "ACK":
return SIPMethodAck, nil
case "BYE":
return SIPMethodBye, nil
case "CANCEL":
return SIPMethodCancel, nil
case "OPTIONS":
return SIPMethodOptions, nil
case "REGISTER":
return SIPMethodRegister, nil
case "PRACK":
return SIPMethodPrack, nil
case "SUBSCRIBE":
return SIPMethodSubscribe, nil
case "NOTIFY":
return SIPMethodNotify, nil
case "PUBLISH":
return SIPMethodPublish, nil
case "INFO":
return SIPMethodInfo, nil
case "REFER":
return SIPMethodRefer, nil
case "MESSAGE":
return SIPMethodMessage, nil
case "UPDATE":
return SIPMethodUpdate, nil
case "PING":
return SIPMethodPing, nil
default:
return 0, fmt.Errorf("Unknown SIP method: '%s'", method)
}
}
// Here is a correspondance between long header names and short
// as defined in rfc3261 in section 20
var compactSipHeadersCorrespondance = map[string]string{
"accept-contact": "a",
"allow-events": "u",
"call-id": "i",
"contact": "m",
"content-encoding": "e",
"content-length": "l",
"content-type": "c",
"event": "o",
"from": "f",
"identity": "y",
"refer-to": "r",
"referred-by": "b",
"reject-contact": "j",
"request-disposition": "d",
"session-expires": "x",
"subject": "s",
"supported": "k",
"to": "t",
"via": "v",
}
// SIP object will contains information about decoded SIP packet.
// -> The SIP Version
// -> The SIP Headers (in a map[string][]string because of multiple headers with the same name
// -> The SIP Method
// -> The SIP Response code (if it's a response)
// -> The SIP Status line (if it's a response)
// You can easily know the type of the packet with the IsResponse boolean
//
type SIP struct {
BaseLayer
// Base information
Version SIPVersion
Method SIPMethod
Headers map[string][]string
// Request
RequestURI string
// Response
IsResponse bool
ResponseCode int
ResponseStatus string
// Private fields
cseq int64
contentLength int64
lastHeaderParsed string
}
// decodeSIP decodes the byte slice into a SIP type. It also
// setups the application Layer in PacketBuilder.
func decodeSIP(data []byte, p gopacket.PacketBuilder) error {
s := NewSIP()
err := s.DecodeFromBytes(data, p)
if err != nil {
return err
}
p.AddLayer(s)
p.SetApplicationLayer(s)
return nil
}
// NewSIP instantiates a new empty SIP object
func NewSIP() *SIP {
s := new(SIP)
s.Headers = make(map[string][]string)
return s
}
// LayerType returns gopacket.LayerTypeSIP.
func (s *SIP) LayerType() gopacket.LayerType {
return LayerTypeSIP
}
// Payload returns the base layer payload
func (s *SIP) Payload() []byte {
return s.BaseLayer.Payload
}
// CanDecode returns the set of layer types that this DecodingLayer can decode
func (s *SIP) CanDecode() gopacket.LayerClass {
return LayerTypeSIP
}
// NextLayerType returns the layer type contained by this DecodingLayer
func (s *SIP) NextLayerType() gopacket.LayerType {
return gopacket.LayerTypePayload
}
// DecodeFromBytes decodes the slice into the SIP struct.
func (s *SIP) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
// Init some vars for parsing follow-up
var countLines int
var line []byte
var err error
// Clean leading new line
data = bytes.Trim(data, "\n")
// Iterate on all lines of the SIP Headers
// and stop when we reach the SDP (aka when the new line
// is at index 0 of the remaining packet)
buffer := bytes.NewBuffer(data)
for {
// Read next line
line, err = buffer.ReadBytes(byte('\n'))
if err != nil {
if err == io.EOF {
break
} else {
return err
}
}
// Trim the new line delimiters
line = bytes.Trim(line, "\r\n")
// Empty line, we hit Body
// Putting packet remain in Paypload
if len(line) == 0 {
s.BaseLayer.Payload = buffer.Bytes()
break
}
// First line is the SIP request/response line
// Other lines are headers
if countLines == 0 {
err = s.ParseFirstLine(line)
if err != nil {
return err
}
} else {
err = s.ParseHeader(line)
if err != nil {
return err
}
}
countLines++
}
return nil
}
// ParseFirstLine will compute the first line of a SIP packet.
// The first line will tell us if it's a request or a response.
//
// Examples of first line of SIP Prococol :
//
// Request : INVITE bob@example.com SIP/2.0
// Response : SIP/2.0 200 OK
// Response : SIP/2.0 501 Not Implemented
//
func (s *SIP) ParseFirstLine(firstLine []byte) error {
var err error
// Splits line by space
splits := strings.SplitN(string(firstLine), " ", 3)
// We must have at least 3 parts
if len(splits) < 3 {
return fmt.Errorf("invalid first SIP line: '%s'", string(firstLine))
}
// Determine the SIP packet type
if strings.HasPrefix(splits[0], "SIP") {
// --> Response
s.IsResponse = true
// Validate SIP Version
s.Version, err = GetSIPVersion(splits[0])
if err != nil {
return err
}
// Compute code
s.ResponseCode, err = strconv.Atoi(splits[1])
if err != nil {
return err
}
// Compute status line
s.ResponseStatus = splits[2]
} else {
// --> Request
// Validate method
s.Method, err = GetSIPMethod(splits[0])
if err != nil {
return err
}
s.RequestURI = splits[1]
// Validate SIP Version
s.Version, err = GetSIPVersion(splits[2])
if err != nil {
return err
}
}
return nil
}
// ParseHeader will parse a SIP Header
// SIP Headers are quite simple, there are colon separated name and value
// Headers can be spread over multiple lines
//
// Examples of header :
//
// CSeq: 1 REGISTER
// Via: SIP/2.0/UDP there.com:5060
// Authorization:Digest username="UserB",
// realm="MCI WorldCom SIP",
// nonce="1cec4341ae6cbe5a359ea9c8e88df84f", opaque="",
// uri="sip:ss2.wcom.com", response="71ba27c64bd01de719686aa4590d5824"
//
func (s *SIP) ParseHeader(header []byte) (err error) {
// Ignore empty headers
if len(header) == 0 {
return
}
// Check if this is the following of last header
// RFC 3261 - 7.3.1 - Header Field Format specify that following lines of
// multiline headers must begin by SP or TAB
if header[0] == '\t' || header[0] == ' ' {
header = bytes.TrimSpace(header)
s.Headers[s.lastHeaderParsed][len(s.Headers[s.lastHeaderParsed])-1] += fmt.Sprintf(" %s", string(header))
return
}
// Find the ':' to separate header name and value
index := bytes.Index(header, []byte(":"))
if index >= 0 {
headerName := strings.ToLower(string(bytes.Trim(header[:index], " ")))
headerValue := string(bytes.Trim(header[index+1:], " "))
// Add header to object
s.Headers[headerName] = append(s.Headers[headerName], headerValue)
s.lastHeaderParsed = headerName
// Compute specific headers
err = s.ParseSpecificHeaders(headerName, headerValue)
if err != nil {
return err
}
}
return nil
}
// ParseSpecificHeaders will parse some specific key values from
// specific headers like CSeq or Content-Length integer values
func (s *SIP) ParseSpecificHeaders(headerName string, headerValue string) (err error) {
switch headerName {
case "cseq":
// CSeq header value is formatted like that :
// CSeq: 123 INVITE
// We split the value to parse Cseq integer value, and method
splits := strings.Split(headerValue, " ")
if len(splits) > 1 {
// Parse Cseq
s.cseq, err = strconv.ParseInt(splits[0], 10, 64)
if err != nil {
return err
}
// Validate method
if s.IsResponse {
s.Method, err = GetSIPMethod(splits[1])
if err != nil {
return err
}
}
}
case "content-length":
// Parse Content-Length
s.contentLength, err = strconv.ParseInt(headerValue, 10, 64)
if err != nil {
return err
}
}
return nil
}
// GetAllHeaders will return the full headers of the
// current SIP packets in a map[string][]string
func (s *SIP) GetAllHeaders() map[string][]string {
return s.Headers
}
// GetHeader will return all the headers with
// the specified name.
func (s *SIP) GetHeader(headerName string) []string {
headerName = strings.ToLower(headerName)
h := make([]string, 0)
if _, ok := s.Headers[headerName]; ok {
if len(s.Headers[headerName]) > 0 {
return s.Headers[headerName]
} else if len(s.Headers[compactSipHeadersCorrespondance[headerName]]) > 0 {
return s.Headers[compactSipHeadersCorrespondance[headerName]]
}
}
return h
}
// GetFirstHeader will return the first header with
// the specified name. If the current SIP packet has multiple
// headers with the same name, it returns the first.
func (s *SIP) GetFirstHeader(headerName string) string {
headerName = strings.ToLower(headerName)
if _, ok := s.Headers[headerName]; ok {
if len(s.Headers[headerName]) > 0 {
return s.Headers[headerName][0]
} else if len(s.Headers[compactSipHeadersCorrespondance[headerName]]) > 0 {
return s.Headers[compactSipHeadersCorrespondance[headerName]][0]
}
}
return ""
}
//
// Some handy getters for most used SIP headers
//
// GetAuthorization will return the Authorization
// header of the current SIP packet
func (s *SIP) GetAuthorization() string {
return s.GetFirstHeader("Authorization")
}
// GetFrom will return the From
// header of the current SIP packet
func (s *SIP) GetFrom() string {
return s.GetFirstHeader("From")
}
// GetTo will return the To
// header of the current SIP packet
func (s *SIP) GetTo() string {
return s.GetFirstHeader("To")
}
// GetContact will return the Contact
// header of the current SIP packet
func (s *SIP) GetContact() string {
return s.GetFirstHeader("Contact")
}
// GetCallID will return the Call-ID
// header of the current SIP packet
func (s *SIP) GetCallID() string {
return s.GetFirstHeader("Call-ID")
}
// GetUserAgent will return the User-Agent
// header of the current SIP packet
func (s *SIP) GetUserAgent() string {
return s.GetFirstHeader("User-Agent")
}
// GetContentLength will return the parsed integer
// Content-Length header of the current SIP packet
func (s *SIP) GetContentLength() int64 {
return s.contentLength
}
// GetCSeq will return the parsed integer CSeq header
// header of the current SIP packet
func (s *SIP) GetCSeq() int64 {
return s.cseq
}