Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/repository/proxy_probe_service.go

@@ -0,0 +1,245 @@
+package repository
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/httpclient"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+)
+
+func NewProxyExitInfoProber(cfg *config.Config) service.ProxyExitInfoProber {
+	insecure := false
+	allowPrivate := false
+	validateResolvedIP := true
+	maxResponseBytes := defaultProxyProbeResponseMaxBytes
+	if cfg != nil {
+		insecure = cfg.Security.ProxyProbe.InsecureSkipVerify
+		allowPrivate = cfg.Security.URLAllowlist.AllowPrivateHosts
+		validateResolvedIP = cfg.Security.URLAllowlist.Enabled
+		if cfg.Gateway.ProxyProbeResponseReadMaxBytes > 0 {
+			maxResponseBytes = cfg.Gateway.ProxyProbeResponseReadMaxBytes
+		}
+	}
+	if insecure {
+		log.Printf("[ProxyProbe] Warning: insecure_skip_verify is not allowed and will cause probe failure.")
+	}
+	// 构建探测 URL 列表：配置存在时覆盖内置默认列表。
+	var configuredTargets []configuredProbeTarget
+	if cfg != nil && len(cfg.Security.ProxyProbe.URLs) > 0 {
+		configuredTargets = make([]configuredProbeTarget, 0, len(cfg.Security.ProxyProbe.URLs))
+		for _, u := range cfg.Security.ProxyProbe.URLs {
+			configuredTargets = append(configuredTargets, configuredProbeTarget{
+				url:    u.URL,
+				parser: u.Parser,
+			})
+		}
+	}
+
+	return &proxyProbeService{
+		insecureSkipVerify:  insecure,
+		allowPrivateHosts:   allowPrivate,
+		validateResolvedIP:  validateResolvedIP,
+		maxResponseBytes:    maxResponseBytes,
+		configuredProbeURLs: configuredTargets,
+	}
+}
+
+const (
+	defaultProxyProbeTimeout          = 10 * time.Second
+	defaultProxyProbeResponseMaxBytes = int64(1024 * 1024)
+)
+
+// probeURLs 按优先级排列的内置探测 URL 列表。
+// 某些 AI API 专用代理只允许访问特定域名，因此需要多个备选。
+var probeURLs = []struct {
+	url    string
+	parser string
+}{
+	{"http://ip-api.com/json/?lang=zh-CN", "ip-api"},
+	{"http://api64.ipify.org?format=json", "ipify"},
+}
+
+type configuredProbeTarget struct {
+	url    string
+	parser string
+}
+
+type proxyProbeService struct {
+	insecureSkipVerify  bool
+	allowPrivateHosts   bool
+	validateResolvedIP  bool
+	maxResponseBytes    int64
+	configuredProbeURLs []configuredProbeTarget
+}
+
+func (s *proxyProbeService) ProbeProxy(ctx context.Context, proxyURL string) (*service.ProxyExitInfo, int64, error) {
+	client, err := httpclient.GetClient(httpclient.Options{
+		ProxyURL:           proxyURL,
+		Timeout:            defaultProxyProbeTimeout,
+		InsecureSkipVerify: s.insecureSkipVerify,
+		ValidateResolvedIP: s.validateResolvedIP,
+		AllowPrivateHosts:  s.allowPrivateHosts,
+	})
+	if err != nil {
+		return nil, 0, fmt.Errorf("failed to create proxy client: %w", err)
+	}
+
+	var lastErr error
+	if len(s.configuredProbeURLs) > 0 {
+		for _, probe := range s.configuredProbeURLs {
+			exitInfo, latencyMs, err := s.probeWithURL(ctx, client, probe.url, probe.parser)
+			if err == nil {
+				return exitInfo, latencyMs, nil
+			}
+			lastErr = err
+		}
+		return nil, 0, fmt.Errorf("all probe URLs failed, last error: %w", lastErr)
+	}
+
+	for _, probe := range probeURLs {
+		exitInfo, latencyMs, err := s.probeWithURL(ctx, client, probe.url, probe.parser)
+		if err == nil {
+			return exitInfo, latencyMs, nil
+		}
+		lastErr = err
+	}
+
+	return nil, 0, fmt.Errorf("all probe URLs failed, last error: %w", lastErr)
+}
+
+func (s *proxyProbeService) probeWithURL(ctx context.Context, client *http.Client, url string, parser string) (*service.ProxyExitInfo, int64, error) {
+	startTime := time.Now()
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return nil, 0, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, 0, fmt.Errorf("proxy connection failed: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	latencyMs := time.Since(startTime).Milliseconds()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, latencyMs, fmt.Errorf("request failed with status: %d", resp.StatusCode)
+	}
+
+	maxResponseBytes := s.maxResponseBytes
+	if maxResponseBytes <= 0 {
+		maxResponseBytes = defaultProxyProbeResponseMaxBytes
+	}
+	body, err := io.ReadAll(io.LimitReader(resp.Body, maxResponseBytes+1))
+	if err != nil {
+		return nil, latencyMs, fmt.Errorf("failed to read response: %w", err)
+	}
+	if int64(len(body)) > maxResponseBytes {
+		return nil, latencyMs, fmt.Errorf("proxy probe response exceeds limit: %d", maxResponseBytes)
+	}
+
+	switch parser {
+	case "ip-api":
+		return s.parseIPAPI(body, latencyMs)
+	case "ipify":
+		return s.parseIPify(body, latencyMs)
+	case "chatgpt-trace":
+		return s.parseChatGPTTrace(body, latencyMs)
+	default:
+		return nil, latencyMs, fmt.Errorf("unknown parser: %s", parser)
+	}
+}
+
+func (s *proxyProbeService) parseIPAPI(body []byte, latencyMs int64) (*service.ProxyExitInfo, int64, error) {
+	var ipInfo struct {
+		Status      string `json:"status"`
+		Message     string `json:"message"`
+		Query       string `json:"query"`
+		City        string `json:"city"`
+		Region      string `json:"region"`
+		RegionName  string `json:"regionName"`
+		Country     string `json:"country"`
+		CountryCode string `json:"countryCode"`
+	}
+
+	if err := json.Unmarshal(body, &ipInfo); err != nil {
+		preview := string(body)
+		if len(preview) > 200 {
+			preview = preview[:200] + "..."
+		}
+		return nil, latencyMs, fmt.Errorf("failed to parse response: %w (body: %s)", err, preview)
+	}
+	if strings.ToLower(ipInfo.Status) != "success" {
+		if ipInfo.Message == "" {
+			ipInfo.Message = "ip-api request failed"
+		}
+		return nil, latencyMs, fmt.Errorf("ip-api request failed: %s", ipInfo.Message)
+	}
+
+	region := ipInfo.RegionName
+	if region == "" {
+		region = ipInfo.Region
+	}
+	return &service.ProxyExitInfo{
+		IP:          ipInfo.Query,
+		City:        ipInfo.City,
+		Region:      region,
+		Country:     ipInfo.Country,
+		CountryCode: ipInfo.CountryCode,
+	}, latencyMs, nil
+}
+
+func (s *proxyProbeService) parseIPify(body []byte, latencyMs int64) (*service.ProxyExitInfo, int64, error) {
+	var result struct {
+		IP string `json:"ip"`
+	}
+	if err := json.Unmarshal(body, &result); err != nil {
+		return nil, latencyMs, fmt.Errorf("failed to parse ipify response: %w", err)
+	}
+	if result.IP == "" {
+		return nil, latencyMs, fmt.Errorf("ipify: no IP found in response")
+	}
+	return &service.ProxyExitInfo{
+		IP: result.IP,
+	}, latencyMs, nil
+}
+
+// parseChatGPTTrace 解析 Cloudflare trace 端点（如 chatgpt.com/cdn-cgi/trace）的纯文本响应。
+// 响应按行给出键值对，其中 ip= 为出口 IP，loc= 为国家代码。
+func (s *proxyProbeService) parseChatGPTTrace(body []byte, latencyMs int64) (*service.ProxyExitInfo, int64, error) {
+	var ip, loc string
+	for _, line := range strings.Split(string(body), "\n") {
+		key, value, found := strings.Cut(strings.TrimSpace(line), "=")
+		if !found {
+			continue
+		}
+		switch key {
+		case "ip":
+			ip = strings.TrimSpace(value)
+		case "loc":
+			loc = strings.TrimSpace(value)
+		}
+	}
+	if ip == "" {
+		preview := string(body)
+		if len(preview) > 200 {
+			preview = preview[:200] + "..."
+		}
+		return nil, latencyMs, fmt.Errorf("chatgpt-trace: no ip= found in response (body: %s)", preview)
+	}
+	info := &service.ProxyExitInfo{
+		IP: ip,
+	}
+	if loc != "" {
+		info.CountryCode = loc
+	}
+	return info, latencyMs, nil
+}