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127 lines
3.2 KiB
127 lines
3.2 KiB
// Copyright 2020 Justine Alexandra Roberts Tunney
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package dialog
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import (
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"log"
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"net"
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"strconv"
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"time"
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"github.com/jart/gosip/sip"
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)
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func ReceiveMessages(sock *net.UDPConn, c chan<- *sip.Msg, e chan<- error) {
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buf := make([]byte, 2048)
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laddr := sock.LocalAddr().(*net.UDPAddr)
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lhost := laddr.IP.String()
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lport := uint16(laddr.Port)
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for {
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amt, addr, err := sock.ReadFromUDP(buf)
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if err != nil {
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e <- err
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break
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}
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ts := time.Now()
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packet := buf[0:amt]
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if *tracing {
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trace("recv", packet, addr)
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}
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msg, err := sip.ParseMsg(packet)
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if err != nil {
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log.Printf("Dropping SIP message: %s\r\n", err)
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continue
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}
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addReceived(msg, addr)
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addTimestamp(msg, ts)
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if msg.Route != nil && msg.Route.Uri.Host == lhost && or5060(msg.Route.Uri.Port) == lport {
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msg.Route = msg.Route.Next
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}
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fixMessagesFromStrictRouters(lhost, lport, msg)
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c <- msg
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}
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close(c)
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close(e) // Must be unbuffered!
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}
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func addReceived(msg *sip.Msg, addr *net.UDPAddr) {
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if msg.IsResponse() {
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return
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}
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if int(msg.Via.Port) != addr.Port {
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rport := msg.Via.Param.Get("rport")
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port := strconv.Itoa(addr.Port)
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if rport == nil {
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msg.Via.Param = &sip.Param{
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Name: "rport",
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Value: port,
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Next: msg.Via.Param,
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}
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} else {
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// implied rport is 5060, but some NAT will use another port,we use real port instead
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if len(rport.Value) == 0 {
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rport.Value = port
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}
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}
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}
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if msg.Via.Host != addr.IP.String() {
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if msg.Via.Param.Get("received") == nil {
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msg.Via.Param = &sip.Param{
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Name: "received",
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Value: addr.IP.String(),
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Next: msg.Via.Param,
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}
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}
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}
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}
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func addTimestamp(msg *sip.Msg, ts time.Time) {
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if *timestampTagging {
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msg.Via.Param = &sip.Param{
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Name: "usi",
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Value: strconv.FormatInt(ts.UnixNano()/int64(time.Microsecond), 10),
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Next: msg.Via.Param,
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}
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}
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}
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// RFC3261 16.4 Route Information Preprocessing
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// RFC3261 16.12.1.2: Traversing a Strict-Routing Proxy
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func fixMessagesFromStrictRouters(lhost string, lport uint16, msg *sip.Msg) {
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if msg.Request != nil &&
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msg.Request.Param.Get("lr") != nil &&
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msg.Route != nil &&
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msg.Request.Host == lhost &&
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or5060(msg.Request.Port) == lport {
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var oldReq, newReq *sip.URI
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if msg.Route.Next == nil {
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oldReq, newReq = msg.Request, msg.Route.Uri
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msg.Request = msg.Route.Uri
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msg.Route = nil
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} else {
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seclast := msg.Route
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for ; seclast.Next.Next != nil; seclast = seclast.Next {
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}
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oldReq, newReq = msg.Request, seclast.Next.Uri
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msg.Request = seclast.Next.Uri
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seclast.Next = nil
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msg.Route.Last()
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}
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log.Printf("Fixing request URI after strict router traversal: %s -> %s\r\n", oldReq, newReq)
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}
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}
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