You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
291 lines
8.1 KiB
291 lines
8.1 KiB
// SIP Transport Layer. Responsible for serializing messages to/from
|
|
// your network.
|
|
|
|
package sip
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"flag"
|
|
"fmt"
|
|
"github.com/jart/gosip/util"
|
|
"log"
|
|
"net"
|
|
"strconv"
|
|
"strings"
|
|
"time"
|
|
)
|
|
|
|
var (
|
|
tracing = flag.Bool("tracing", false, "Enable SIP message tracing")
|
|
timestampTagging = flag.Bool("timestampTagging", false, "Add microsecond timestamps to Via tags")
|
|
)
|
|
|
|
// Transport defines any object capable of sending and receiving SIP messages.
|
|
// Such objects are responsible for their own reliability. This means checking
|
|
// network errors, raising alarms, rebinding sockets, etc.
|
|
type Transport interface {
|
|
// Sends a SIP message. Will not modify msg.
|
|
Send(msg *Msg) error
|
|
|
|
// Receives a SIP message. Must only be called by one goroutine. The received
|
|
// address is injected into the first Via header as the "received" param.
|
|
Recv() (msg *Msg, err error)
|
|
|
|
// Closes underlying resources. Please make sure all calls using this
|
|
// transport complete first.
|
|
Close() error
|
|
|
|
// When you send an outbound request (not a response) you have to set the via
|
|
// tag: ``msg.Via = tport.Via().SetBranch().SetNext(msg.Via)``. The details
|
|
// of the branch parameter... are tricky.
|
|
Via() *Via
|
|
|
|
// Returns a linked list of all canonical names and/or IP addresses that may
|
|
// be used to contact *this specific* transport.
|
|
Contact() *Addr
|
|
}
|
|
|
|
// Transport implementation that serializes messages to/from a UDP socket.
|
|
type udpTransport struct {
|
|
sock *net.UDPConn // thing returned by ListenUDP
|
|
addr *net.UDPAddr // handy for getting ip (contact might be host)
|
|
buf []byte // reusable memory for serialization
|
|
via *Via // who are we?
|
|
contact *Addr // uri that points to this specific transport
|
|
}
|
|
|
|
// Creates a new stateless network mechanism for transmitting and receiving SIP
|
|
// signalling messages.
|
|
//
|
|
// 'contact' is a SIP address, e.g. "<sip:1.2.3.4>", that tells how to bind
|
|
// sockets. This value is also used for contact headers which tell other
|
|
// user-agents where to send responses and hence should only contain an IP or
|
|
// canonical address.
|
|
func NewUDPTransport(contact *Addr) (tp Transport, err error) {
|
|
saddr := util.HostPortToString(contact.Uri.Host, contact.Uri.Port)
|
|
sock, err := net.ListenPacket("udp", saddr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
addr := sock.LocalAddr().(*net.UDPAddr)
|
|
contact = contact.Copy()
|
|
contact.Uri.Port = uint16(addr.Port)
|
|
contact.Uri.Params["transport"] = addr.Network()
|
|
return &udpTransport{
|
|
sock: sock.(*net.UDPConn),
|
|
addr: addr,
|
|
buf: make([]byte, 2048),
|
|
contact: contact,
|
|
via: &Via{
|
|
Version: "2.0",
|
|
Proto: strings.ToUpper(addr.Network()),
|
|
Host: contact.Uri.Host,
|
|
Port: contact.Uri.Port,
|
|
},
|
|
}, nil
|
|
}
|
|
|
|
func (tp *udpTransport) Send(msg *Msg) error {
|
|
msg, saddr, err := tp.route(msg)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
addr, err := net.ResolveUDPAddr("ip", saddr)
|
|
if err != nil {
|
|
return errors.New(fmt.Sprintf(
|
|
"udpTransport(%s) failed to resolve %s: %s", tp.addr, saddr, err))
|
|
}
|
|
msg.MaxForwards--
|
|
ts := time.Now()
|
|
addTimestamp(msg, ts)
|
|
var b bytes.Buffer
|
|
msg.Append(&b)
|
|
if *tracing {
|
|
tp.trace("send", b.String(), addr, ts)
|
|
}
|
|
_, err = tp.sock.WriteTo(b.Bytes(), addr)
|
|
if err != nil {
|
|
return errors.New(fmt.Sprintf(
|
|
"udpTransport(%s) write failed: %s", tp.addr, err))
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (tp *udpTransport) Recv() (msg *Msg, err error) {
|
|
for {
|
|
amt, addr, err := tp.sock.ReadFromUDP(tp.buf)
|
|
if err != nil {
|
|
return nil, errors.New(fmt.Sprintf(
|
|
"udpTransport(%s) read failed: %s", tp.addr, err))
|
|
}
|
|
ts := time.Now()
|
|
packet := string(tp.buf[0:amt])
|
|
if *tracing {
|
|
tp.trace("recv", packet, addr, ts)
|
|
}
|
|
// Validation: http://tools.ietf.org/html/rfc3261#section-16.3
|
|
msg, err = ParseMsg(packet)
|
|
if err != nil {
|
|
log.Printf("udpTransport(%s) got bad message from %s: %s\n%s", tp.addr, addr, err, packet)
|
|
continue
|
|
}
|
|
if msg.Via.Host != addr.IP.String() || int(msg.Via.Port) != addr.Port {
|
|
msg.Via.Params["received"] = addr.String()
|
|
}
|
|
addTimestamp(msg, ts)
|
|
if !tp.sanityCheck(msg) {
|
|
continue
|
|
}
|
|
tp.preprocess(msg)
|
|
break
|
|
}
|
|
return msg, nil
|
|
}
|
|
|
|
func (tp *udpTransport) Via() *Via {
|
|
return tp.via
|
|
}
|
|
|
|
func (tp *udpTransport) Contact() *Addr {
|
|
return tp.contact
|
|
}
|
|
|
|
func (tp *udpTransport) Close() error {
|
|
return tp.sock.Close()
|
|
}
|
|
|
|
func (tp *udpTransport) trace(dir, pkt string, addr net.Addr, t time.Time) {
|
|
size := len(pkt)
|
|
bar := strings.Repeat("-", 72)
|
|
suffix := "\n "
|
|
if pkt[len(pkt)-1] == '\n' {
|
|
suffix = ""
|
|
}
|
|
log.Printf(
|
|
"%s %d bytes to %s/%s at %s\n"+
|
|
"%s\n"+
|
|
"%s%s"+
|
|
"%s\n",
|
|
dir, size, addr.Network(), addr.String(),
|
|
t.Format(time.RFC3339Nano),
|
|
bar,
|
|
strings.Replace(pkt, "\n", "\n ", -1), suffix,
|
|
bar)
|
|
}
|
|
|
|
// Test if this message is acceptable.
|
|
func (tp *udpTransport) sanityCheck(msg *Msg) bool {
|
|
if msg.MaxForwards <= 0 {
|
|
log.Printf("udpTransport(%s) froot loop detected\n%s", tp.addr, msg)
|
|
go tp.Send(NewResponse(msg, 483))
|
|
return false
|
|
}
|
|
if msg.IsResponse {
|
|
if msg.Status >= 700 {
|
|
log.Printf("udpTransport(%s) msg has crazy status number\n%s", tp.addr, msg)
|
|
go tp.Send(NewResponse(msg, 400))
|
|
return false
|
|
}
|
|
} else {
|
|
if msg.CSeqMethod == "" || msg.CSeqMethod != msg.Method {
|
|
log.Printf("udpTransport(%s) bad cseq number\n%s", tp.addr, msg)
|
|
go tp.Send(NewResponse(msg, 400))
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Perform some ingress message mangling.
|
|
func (tp *udpTransport) preprocess(msg *Msg) {
|
|
if tp.contact.Compare(msg.Route) {
|
|
log.Printf("udpTransport(%s) removing our route header: %s", tp.addr, msg.Route)
|
|
msg.Route = msg.Route.Next
|
|
}
|
|
if _, ok := msg.Request.Params["lr"]; ok && msg.Route != nil && tp.contact.Uri.Compare(msg.Request) {
|
|
// RFC3261 16.4 Route Information Preprocessing
|
|
// RFC3261 16.12.1.2: Traversing a Strict-Routing Proxy
|
|
var oldReq, newReq *URI
|
|
if msg.Route.Next == nil {
|
|
oldReq, newReq = msg.Request, msg.Route.Uri
|
|
msg.Request = msg.Route.Uri
|
|
msg.Route = nil
|
|
} else {
|
|
seclast := msg.Route
|
|
for ; seclast.Next.Next != nil; seclast = seclast.Next {
|
|
}
|
|
oldReq, newReq = msg.Request, seclast.Next.Uri
|
|
msg.Request = seclast.Next.Uri
|
|
seclast.Next = nil
|
|
msg.Route.Last()
|
|
}
|
|
log.Printf("udpTransport(%s) fixing request uri after strict router traversal: %s -> %s",
|
|
tp.addr, oldReq, newReq)
|
|
}
|
|
}
|
|
|
|
func (tp *udpTransport) route(old *Msg) (msg *Msg, saddr string, err error) {
|
|
var host string
|
|
var port uint16
|
|
msg = new(Msg)
|
|
*msg = *old // Shallow copy is sufficient.
|
|
if msg.IsResponse {
|
|
msg.Via = old.Via.Copy()
|
|
if msg.Via.CompareAddr(tp.via) {
|
|
// In proxy scenarios we have to remove our own Via.
|
|
msg.Via = msg.Via.Next
|
|
}
|
|
if msg.Via == nil {
|
|
return nil, "", errors.New("Ran out of Via headers when forwarding Response!")
|
|
}
|
|
if msg.Via != nil {
|
|
if received, ok := msg.Via.Params["received"]; ok {
|
|
return msg, received, nil
|
|
} else {
|
|
host, port = msg.Via.Host, msg.Via.Port
|
|
}
|
|
} else {
|
|
return nil, "", errors.New("Message missing Via header")
|
|
}
|
|
} else {
|
|
if msg.Request == nil {
|
|
return nil, "", errors.New("Missing request URI")
|
|
}
|
|
if !msg.Via.CompareAddr(tp.via) {
|
|
return nil, "", errors.New("You forgot to say: msg.Via = tp.Via(msg.Via)")
|
|
}
|
|
if msg.Route != nil {
|
|
if msg.Method == "REGISTER" {
|
|
return nil, "", errors.New("Don't loose route register requests")
|
|
}
|
|
if _, ok := msg.Route.Uri.Params["lr"]; ok {
|
|
// RFC3261 16.12.1.1 Basic SIP Trapezoid
|
|
route := msg.Route
|
|
msg.Route = msg.Route.Next
|
|
host, port = route.Uri.Host, route.Uri.Port
|
|
} else {
|
|
// RFC3261 16.12.1.2: Traversing a Strict-Routing Proxy
|
|
msg.Route = old.Route.Copy()
|
|
msg.Route.Last().Next = &Addr{Uri: msg.Request}
|
|
msg.Request = msg.Route.Uri
|
|
msg.Route = msg.Route.Next
|
|
host, port = msg.Request.Host, msg.Request.Port
|
|
}
|
|
} else {
|
|
host, port = msg.Request.Host, msg.Request.Port
|
|
}
|
|
}
|
|
if msg.OutboundProxy != "" {
|
|
saddr = msg.OutboundProxy
|
|
} else {
|
|
saddr = util.HostPortToString(host, port)
|
|
}
|
|
return
|
|
}
|
|
|
|
func addTimestamp(msg *Msg, ts time.Time) {
|
|
if *timestampTagging {
|
|
msg.Via.Params["µsi"] = strconv.FormatInt(ts.UnixNano()/int64(time.Microsecond), 10)
|
|
}
|
|
}
|