feat: take the client address from proxies in private networks

internal/adapter/in/api/api.go

@@ -65,6 +65,8 @@ type call struct {
 	ticket string
 	// 票据是常驻房间的 API Key。
 	bot bool
+	// 发出请求的客户端地址，按来源限流时使用。
+	clientIP string
 }
 
 type handlerFunc func(ctx context.Context, c call) (any, error)
@@ -180,7 +182,7 @@ func (s *server) serve(ctx context.Context, w http.ResponseWriter, r *http.Reque
 			logCtx, err = ctx, s.panicked(ctx, r, value)
 		}
 	}()
-	c := call{r: r}
+	c := call{r: r, clientIP: clientIP(r)}
 	switch auth {
 	case protocol.AuthNone:
 	case protocol.AuthMember:

internal/adapter/in/api/clientip.go

@@ -0,0 +1,42 @@
+package api
+
+import (
+	"net/http"
+	"net/netip"
+	"strings"
+)
+
+// 只有对端是回环、私有网段或链路本地地址的代理时才读 X-Forwarded-For，因为其他来源可以随意填写它。从最右端往左跳过受信任的代理，
+// 第一个不受信任的地址就是客户端；全部受信任时取最左端的地址。受信任的代理只会写入合法的地址，
+// 遇到不合法的值说明已经到了客户端自己填写的部分，此时改用对端地址。
+func clientIP(r *http.Request) string {
+	peer, err := netip.ParseAddrPort(r.RemoteAddr)
+	if err != nil {
+		return r.RemoteAddr
+	}
+	addr := peer.Addr().Unmap()
+	if !trustedProxy(addr) {
+		return addr.String()
+	}
+	var hops []string
+	for _, v := range r.Header.Values("X-Forwarded-For") {
+		for hop := range strings.SplitSeq(v, ",") {
+			hops = append(hops, strings.TrimSpace(hop))
+		}
+	}
+	for i := len(hops) - 1; i >= 0; i-- {
+		hop, err := netip.ParseAddr(hops[i])
+		if err != nil {
+			break
+		}
+		hop = hop.Unmap()
+		if i == 0 || !trustedProxy(hop) {
+			return hop.String()
+		}
+	}
+	return addr.String()
+}
+
+func trustedProxy(addr netip.Addr) bool {
+	return addr.IsLoopback() || addr.IsPrivate() || addr.IsLinkLocalUnicast()
+}

internal/adapter/in/api/clientip_test.go

@@ -0,0 +1,41 @@
+package api
+
+import (
+	"net/http/httptest"
+	"testing"
+)
+
+func TestClientIP(t *testing.T) {
+	cases := []struct {
+		name      string
+		remote    string
+		forwarded []string
+		want      string
+	}{
+		{"公网对端不看 X-Forwarded-For", "203.0.113.7:4321", []string{"198.51.100.1"}, "203.0.113.7"},
+		{"私有网段的代理转发时取公网客户端地址", "10.42.0.153:4321", []string{"203.0.113.7"}, "203.0.113.7"},
+		{"回环对端同样可信", "127.0.0.1:4321", []string{"203.0.113.7"}, "203.0.113.7"},
+		{"IPv6 回环对端同样可信", "[::1]:4321", []string{"203.0.113.7"}, "203.0.113.7"},
+		{"链路本地对端同样可信", "[fe80::1]:4321", []string{"203.0.113.7"}, "203.0.113.7"},
+		{"链式代理跳过右端的私有地址", "127.0.0.1:4321", []string{"203.0.113.7, 10.42.0.1, 192.168.1.2"}, "203.0.113.7"},
+		{"客户端自己填在左边的地址不采用", "10.42.0.153:4321", []string{"198.51.100.1, 203.0.113.7"}, "203.0.113.7"},
+		{"多个头按顺序拼接", "10.42.0.153:4321", []string{"198.51.100.1", "203.0.113.7"}, "203.0.113.7"},
+		{"全部是私有地址时取最左端", "10.42.0.153:4321", []string{"192.168.1.5, 10.42.0.1"}, "192.168.1.5"},
+		{"没有 X-Forwarded-For 时取对端", "10.42.0.153:4321", nil, "10.42.0.153"},
+		{"遇到不合法的地址就停下，取对端", "10.42.0.153:4321", []string{"203.0.113.7, unknown, 10.42.0.1"}, "10.42.0.153"},
+		{"IPv4 映射的 IPv6 对端按 IPv4 处理", "[::ffff:10.42.0.153]:4321", []string{"::ffff:203.0.113.7"}, "203.0.113.7"},
+		{"IPv4 映射的 IPv6 私有跳按 IPv4 处理", "10.42.0.153:4321", []string{"203.0.113.7, ::ffff:10.42.0.1"}, "203.0.113.7"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			r := httptest.NewRequest("GET", "/", nil)
+			r.RemoteAddr = tc.remote
+			for _, v := range tc.forwarded {
+				r.Header.Add("X-Forwarded-For", v)
+			}
+			if got := clientIP(r); got != tc.want {
+				t.Errorf("clientIP = %q，期望 %q", got, tc.want)
+			}
+		})
+	}
+}

web/nginx/templates/alisten.d/proxy.conf.template

@@ -9,6 +9,7 @@ absolute_redirect off;
 location ^~ /api/ {
     # 不小于 serve 的请求体上限，请求体就不会写入临时文件，也就不会因此输出纯文本的 warn 日志。
     client_body_buffer_size 64k;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
     proxy_pass http://$serve;
 }
 location ^~ /media/ {