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dns: support multiple upstream servers

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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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25
dns/client.go
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@ -7,6 +7,7 @@ import (
"io" "io"
"net" "net"
"strings" "strings"
"time"
"github.com/nadoo/glider/common/log" "github.com/nadoo/glider/common/log"
"github.com/nadoo/glider/proxy" "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) { func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (server, network string, respBytes []byte, err error) {
// use tcp to connect upstream server default // use tcp to connect upstream server default
network = "tcp" network = "tcp"
dialer := c.dialer.NextDialer(qname + ":53") dialer := c.dialer.NextDialer(qname + ":53")
// If client uses udp and no forwarders specified, use udp // If client uses udp and no forwarders specified, use udp
@ -113,11 +113,14 @@ func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (server
network = "udp" network = "udp"
} }
server = c.GetServer(qname) servers := c.GetServers(qname)
for _, server = range servers {
rc, err := dialer.Dial(network, server) 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 { if err != nil {
log.F("[dns] failed to connect to server %v: %v", server, err) log.F("[dns] failed to connect to server %v: %v", server, err)
return continue
} }
switch network { switch network {
@ -127,7 +130,13 @@ func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (server
respBytes, err = c.exchangeUDP(rc, reqBytes) respBytes, err = c.exchangeUDP(rc, reqBytes)
} }
return if err == nil {
break
}
log.F("[dns] failed to exchange with server %v: %v", server, err)
}
return server, network, respBytes, err
} }
// exchangeTCP exchange with server over tcp // 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...) c.upServerMap[domain] = append(c.upServerMap[domain], servers...)
} }
// GetServer . // GetServers .
func (c *Client) GetServer(domain string) string { func (c *Client) GetServers(domain string) []string {
domainParts := strings.Split(domain, ".") domainParts := strings.Split(domain, ".")
length := len(domainParts) length := len(domainParts)
for i := length - 2; i >= 0; i-- { for i := length - 2; i >= 0; i-- {
domain := strings.Join(domainParts[i:length], ".") domain := strings.Join(domainParts[i:length], ".")
if servers, ok := c.upServerMap[domain]; ok { if servers, ok := c.upServerMap[domain]; ok {
return servers[0] return servers
} }
} }
// TODO: // TODO:
return c.upServers[0] return c.upServers
} }
// AddHandler . // AddHandler .