Fix #18, support custom

upstream dns port

conf/sower.toml

@@ -4,7 +4,7 @@ password="12345678"
 server_port="5533"
 # server_addr="remote-server"   # replce it to remote server
 http_proxy=":8080"              # eg: 192.168.0.2:8080
-dns_server=""                   # Keep empty for dynamic setting from net env
+dns_server=""                   # eg: 113.5.5.5:53, Keep empty for dynamic setting from net env
 client_ip="127.0.0.1"           # listen the IP, dns target is the IP
 # clear_dns_cache="pkill mDNSResponder || true"   # Windows: "ipconfig /flushdnss"
 suggest_level="SPEEDUP"         # DISABLE, BLOCK, SPEEDUP

dns/dns.go

@@ -23,7 +23,9 @@ func StartDNS(dnsServer, listenIP string, suggestCh chan<- string, level string)
 
 	dhcpCh := make(chan struct{})
 	if dnsServer != "" {
-		dnsServer = net.JoinHostPort(dnsServer, "53")
+		if !strings.ContainsRune(dnsServer, ':') {
+			dnsServer = net.JoinHostPort(dnsServer, "53")
+		}
 	} else {
 		go dynamicSetUpstreamDNS(listenIP, &dnsServer, dhcpCh)
 		dhcpCh <- struct{}{}