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Merge pull request #891 from mavenugo/tcpdns

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Adding TCP listener to the resolver
This commit is contained in:
aboch 2016-01-22 19:58:16 -05:00
commit 079ec162bc
1 changed files with 34 additions and 7 deletions
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41
libnetwork/resolver.go
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@ -41,11 +41,13 @@ const (
// resolver implements the Resolver interface
type resolver struct {
sb *sandbox
extDNS []string
server *dns.Server
conn *net.UDPConn
err error
sb *sandbox
extDNS []string
server *dns.Server
conn *net.UDPConn
tcpServer *dns.Server
tcpListen *net.TCPListener
err error
}
// NewResolver creates a new instance of the Resolver
@ -60,6 +62,7 @@ func (r *resolver) SetupFunc() func() {
return (func() {
var err error
// DNS operates primarily on UDP
addr := &net.UDPAddr{
IP: net.ParseIP(resolverIP),
}
@ -72,9 +75,23 @@ func (r *resolver) SetupFunc() func() {
laddr := r.conn.LocalAddr()
_, ipPort, _ := net.SplitHostPort(laddr.String())
// Listen on a TCP as well
tcpaddr := &net.TCPAddr{
IP: net.ParseIP(resolverIP),
}
r.tcpListen, err = net.ListenTCP("tcp", tcpaddr)
if err != nil {
r.err = fmt.Errorf("error in opening name TCP server socket %v", err)
return
}
ltcpaddr := r.tcpListen.Addr()
_, tcpPort, _ := net.SplitHostPort(ltcpaddr.String())
rules := [][]string{
{"-t", "nat", "-A", "OUTPUT", "-d", resolverIP, "-p", "udp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", laddr.String()},
{"-t", "nat", "-A", "POSTROUTING", "-s", resolverIP, "-p", "udp", "--sport", ipPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
{"-t", "nat", "-A", "OUTPUT", "-d", resolverIP, "-p", "tcp", "--dport", dnsPort, "-j", "DNAT", "--to-destination", ltcpaddr.String()},
{"-t", "nat", "-A", "POSTROUTING", "-s", resolverIP, "-p", "tcp", "--sport", tcpPort, "-j", "SNAT", "--to-source", ":" + dnsPort},
}
for _, rule := range rules {
@ -97,6 +114,12 @@ func (r *resolver) Start() error {
go func() {
s.ActivateAndServe()
}()
tcpServer := &dns.Server{Handler: r, Listener: r.tcpListen}
r.tcpServer = tcpServer
go func() {
tcpServer.ActivateAndServe()
}()
return nil
}
@ -104,7 +127,11 @@ func (r *resolver) Stop() {
if r.server != nil {
r.server.Shutdown()
}
if r.tcpServer != nil {
r.tcpServer.Shutdown()
}
r.conn = nil
r.tcpServer = nil
r.err = fmt.Errorf("setup not done yet")
}
@ -195,9 +222,9 @@ func (r *resolver) ServeDNS(w dns.ResponseWriter, query *dns.Msg) {
num = len(r.extDNS)
}
for i := 0; i < num; i++ {
log.Debugf("Querying ext dns %s for %s[%d]", r.extDNS[i], name, query.Question[0].Qtype)
log.Debugf("Querying ext dns %s:%s for %s[%d]", w.LocalAddr().Network(), r.extDNS[i], name, query.Question[0].Qtype)
c := &dns.Client{Net: "udp"}
c := &dns.Client{Net: w.LocalAddr().Network()}
addr := fmt.Sprintf("%s:%d", r.extDNS[i], 53)
resp, _, err = c.Exchange(query, addr)