ginuerzh
684a0ddf65
When no forwarder or dns metadata is configured, the DNS handler now reads system nameservers from /etc/resolv.conf (Unix) before falling back to the hardcoded 127.0.0.1:53 default. This makes the DNS proxy work out-of-the-box without requiring explicit DNS server configuration. Fixes go-gost/gost#89
51 lines
1.1 KiB
Go
51 lines
1.1 KiB
Go
//go:build !windows
|
|
|
|
package dns
|
|
|
|
import (
|
|
"bufio"
|
|
"fmt"
|
|
"net"
|
|
"os"
|
|
"strings"
|
|
)
|
|
|
|
// systemNameservers reads the system DNS configuration from /etc/resolv.conf
|
|
// and returns the nameserver addresses as URL-like strings suitable for
|
|
// exchanger.NewExchanger (e.g., "udp://1.1.1.1:53").
|
|
// Returns nil if the file cannot be read or contains no nameserver entries.
|
|
func systemNameservers() []string {
|
|
f, err := os.Open("/etc/resolv.conf")
|
|
if err != nil {
|
|
return nil
|
|
}
|
|
defer f.Close()
|
|
|
|
var servers []string
|
|
scanner := bufio.NewScanner(f)
|
|
for scanner.Scan() {
|
|
line := strings.TrimSpace(scanner.Text())
|
|
if line == "" || line[0] == '#' || line[0] == ';' {
|
|
continue
|
|
}
|
|
fields := strings.Fields(line)
|
|
if len(fields) < 2 || fields[0] != "nameserver" {
|
|
continue
|
|
}
|
|
addr := fields[1]
|
|
// Verify it's a valid IP address.
|
|
if ip := net.ParseIP(addr); ip == nil {
|
|
continue
|
|
}
|
|
// If no port, default to 53.
|
|
if _, _, err := net.SplitHostPort(addr); err != nil {
|
|
addr = net.JoinHostPort(addr, "53")
|
|
}
|
|
servers = append(servers, fmt.Sprintf("udp://%s", addr))
|
|
}
|
|
if err := scanner.Err(); err != nil {
|
|
return nil
|
|
}
|
|
return servers
|
|
}
|