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dns: support multiple upstream servers

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This commit is contained in:
nadoo 2018-08-05 23:41:34 +08:00
parent 2cba536ab4
commit 09b6d59394
1 changed files with 27 additions and 18 deletions
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45
dns/client.go
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@ -7,6 +7,7 @@ import (
"io"
"net"
"strings"
"time"
"github.com/nadoo/glider/common/log"
"github.com/nadoo/glider/proxy"
@ -105,7 +106,6 @@ func (c *Client) Exchange(reqBytes []byte, clientAddr string, preferTCP bool) ([
func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (server, network string, respBytes []byte, err error) {
// use tcp to connect upstream server default
network = "tcp"
dialer := c.dialer.NextDialer(qname + ":53")
// If client uses udp and no forwarders specified, use udp
@ -113,21 +113,30 @@ func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (server
network = "udp"
}
server = c.GetServer(qname)
rc, err := dialer.Dial(network, server)
if err != nil {
log.F("[dns] failed to connect to server %v: %v", server, err)
return
servers := c.GetServers(qname)
for _, server = range servers {
rc, err := dialer.Dial(network, server)
// TODO: check the timeout setting here, some dns client has 5 seconds timeout
rc.SetDeadline(time.Now().Add(time.Duration(3) * time.Second))
if err != nil {
log.F("[dns] failed to connect to server %v: %v", server, err)
continue
}
switch network {
case "tcp":
respBytes, err = c.exchangeTCP(rc, reqBytes)
case "udp":
respBytes, err = c.exchangeUDP(rc, reqBytes)
}
if err == nil {
break
}
log.F("[dns] failed to exchange with server %v: %v", server, err)
}
switch network {
case "tcp":
respBytes, err = c.exchangeTCP(rc, reqBytes)
case "udp":
respBytes, err = c.exchangeUDP(rc, reqBytes)
}
return
return server, network, respBytes, err
}
// exchangeTCP exchange with server over tcp
@ -181,20 +190,20 @@ func (c *Client) SetServer(domain string, servers ...string) {
c.upServerMap[domain] = append(c.upServerMap[domain], servers...)
}
// GetServer .
func (c *Client) GetServer(domain string) string {
// GetServers .
func (c *Client) GetServers(domain string) []string {
domainParts := strings.Split(domain, ".")
length := len(domainParts)
for i := length - 2; i >= 0; i-- {
domain := strings.Join(domainParts[i:length], ".")
if servers, ok := c.upServerMap[domain]; ok {
return servers[0]
return servers
}
}
// TODO:
return c.upServers[0]
return c.upServers
}
// AddHandler .