0fe058254c
On Android, /etc/resolv.conf does not exist, causing Go's default DNS resolution to fail. This adds an init() hook that: 1. Detects missing /etc/resolv.conf (Android environment) 2. Configures a custom resolver with PreferGo: true 3. Supports multiple DNS servers via PICOCLAW_DNS_SERVER env var - Semicolon-separated: "8.8.8.8:53;1.1.1.1:53" - Single server also works: "8.8.8.8" - Auto-appends :53 if port omitted 4. Round-robin rotation across configured servers 5. Defaults to Google DNS + Cloudflare DNS Also patches http.DefaultTransport to use the custom resolver.
64 lines
1.5 KiB
Go
64 lines
1.5 KiB
Go
package main
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import (
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"context"
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"net"
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"net/http"
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"os"
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"strings"
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"sync/atomic"
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"time"
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)
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func init() {
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// 仅在 /etc/resolv.conf 不存在时才覆盖（即 Android 环境）
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if _, err := os.Stat("/etc/resolv.conf"); err == nil {
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return
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}
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// 从环境变量获取 DNS server 列表，多个用 ; 隔开
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// 例如: PICOCLAW_DNS_SERVER="8.8.8.8:53;1.1.1.1:53;223.5.5.5:53"
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dnsEnv := os.Getenv("PICOCLAW_DNS_SERVER")
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if dnsEnv == "" {
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dnsEnv = "8.8.8.8:53;1.1.1.1:53"
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}
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var dnsServers []string
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for _, s := range strings.Split(dnsEnv, ";") {
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s = strings.TrimSpace(s)
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if s != "" {
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// 如果没有带端口号，自动补上 :53
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if _, _, err := net.SplitHostPort(s); err != nil {
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s = s + ":53"
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}
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dnsServers = append(dnsServers, s)
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}
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}
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// 轮询索引，在多个 DNS 服务器之间轮转
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var idx uint64
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customResolver := &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
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d := net.Dialer{Timeout: 5 * time.Second}
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// Round-robin: 依次尝试不同的 DNS 服务器
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server := dnsServers[atomic.AddUint64(&idx, 1)%uint64(len(dnsServers))]
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return d.DialContext(ctx, "udp", server)
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},
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}
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// 覆盖全局 DefaultResolver
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net.DefaultResolver = customResolver
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// 覆盖 http.DefaultTransport 使用自定义 DNS 解析的 DialContext
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dialer := &net.Dialer{
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Timeout: 30 * time.Second,
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KeepAlive: 30 * time.Second,
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Resolver: customResolver,
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}
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if tr, ok := http.DefaultTransport.(*http.Transport); ok {
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tr.DialContext = dialer.DialContext
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}
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}
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