🚸 取 Agent IP 优化，直接分 IPv4/IPv6 访问

cmd/agent/monitor/myip.go

@@ -1,11 +1,17 @@
 package monitor
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
+	"strings"
 	"time"
+
+	"github.com/miekg/dns"
 )
 
 type geoIP struct {
@@ -13,22 +19,24 @@ type geoIP struct {
 	IP          string `json:"ip,omitempty"`
 }
 
-var ipv4Servers = []string{
-	"https://api-ipv4.ip.sb/geoip",
-	"https://ip4.seeip.org/geoip",
-}
-
-var ipv6Servers = []string{
-	"https://ip6.seeip.org/geoip",
-	"https://api-ipv6.ip.sb/geoip",
-}
-
-var cachedIP, cachedCountry string
+var (
+	ipv4Servers = []string{
+		"https://api-ipv4.ip.sb/geoip",
+		"https://ip4.seeip.org/geoip",
+	}
+	ipv6Servers = []string{
+		"https://ip6.seeip.org/geoip",
+		"https://api-ipv6.ip.sb/geoip",
+	}
+	cachedIP, cachedCountry string
+	httpClientV4            = newHTTPClient(time.Second*20, time.Second*5, time.Second*10, false)
+	httpClientV6            = newHTTPClient(time.Second*20, time.Second*5, time.Second*10, true)
+)
 
 func UpdateIP() {
 	for {
-		ipv4 := fetchGeoIP(ipv4Servers)
-		ipv6 := fetchGeoIP(ipv6Servers)
+		ipv4 := fetchGeoIP(ipv4Servers, false)
+		ipv6 := fetchGeoIP(ipv6Servers, true)
 		cachedIP = fmt.Sprintf("ip(v4:%s,v6:%s)", ipv4.IP, ipv6.IP)
 		if ipv4.CountryCode != "" {
 			cachedCountry = ipv4.CountryCode
@@ -39,10 +47,16 @@ func UpdateIP() {
 	}
 }
 
-func fetchGeoIP(servers []string) geoIP {
+func fetchGeoIP(servers []string, isV6 bool) geoIP {
 	var ip geoIP
+	var resp *http.Response
+	var err error
 	for i := 0; i < len(servers); i++ {
-		resp, err := http.Get(servers[i])
+		if isV6 {
+			resp, err = httpClientV6.Get(servers[i])
+		} else {
+			resp, err = httpClientV4.Get(servers[i])
+		}
 		if err == nil {
 			body, err := ioutil.ReadAll(resp.Body)
 			if err != nil {
@@ -58,3 +72,70 @@ func fetchGeoIP(servers []string) geoIP {
 	}
 	return ip
 }
+
+func newHTTPClient(httpTimeout, dialTimeout, keepAliveTimeout time.Duration, ipv6 bool) *http.Client {
+	dialer := &net.Dialer{
+		Timeout:   dialTimeout,
+		KeepAlive: keepAliveTimeout,
+	}
+
+	transport := &http.Transport{
+		Proxy:             http.ProxyFromEnvironment,
+		ForceAttemptHTTP2: false,
+		DialContext: func(ctx context.Context, network string, addr string) (net.Conn, error) {
+			ip, err := resolveIP(addr, ipv6)
+			if err != nil {
+				return nil, err
+			}
+			return dialer.DialContext(ctx, network, ip)
+		},
+	}
+
+	return &http.Client{
+		Transport: transport,
+		Timeout:   httpTimeout,
+	}
+}
+
+func resolveIP(addr string, ipv6 bool) (string, error) {
+	url := strings.Split(addr, ":")
+
+	m := new(dns.Msg)
+	if ipv6 {
+		m.SetQuestion(dns.Fqdn(url[0]), dns.TypeAAAA)
+	} else {
+		m.SetQuestion(dns.Fqdn(url[0]), dns.TypeA)
+	}
+	m.RecursionDesired = true
+
+	c := new(dns.Client)
+	r, _, err := c.Exchange(m, net.JoinHostPort("1.1.1.1", "53"))
+	if err != nil {
+		return "", err
+	}
+
+	var ipv4Resolved, ipv6Resolved bool
+	for _, ans := range r.Answer {
+		if ipv6 {
+			if aaaa, ok := ans.(*dns.AAAA); ok {
+				url[0] = aaaa.AAAA.String()
+				ipv6Resolved = true
+			}
+		} else {
+			if a, ok := ans.(*dns.A); ok {
+				url[0] = a.A.String()
+				ipv4Resolved = true
+			}
+		}
+	}
+
+	if ipv6 && !ipv6Resolved {
+		return "", errors.New("the AAAA record not resolved")
+	}
+
+	if !ipv6 && !ipv4Resolved {
+		return "", errors.New("the A record not resolved")
+	}
+
+	return strings.Join(url, ":"), nil
+}