added real_ip and cloudflare_real_ip middlewares, fixed that some middlewares does not work properly

internal/net/http/middleware/cloudflare_real_ip.go

@@ -0,0 +1,118 @@
+package middleware
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/sirupsen/logrus"
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
+)
+
+const (
+	cfIPv4CIDRsEndpoint        = "https://www.cloudflare.com/ips-v4"
+	cfIPv6CIDRsEndpoint        = "https://www.cloudflare.com/ips-v6"
+	cfCIDRsUpdateInterval      = time.Hour
+	cfCIDRsUpdateRetryInterval = 3 * time.Second
+)
+
+var (
+	cfCIDRsLastUpdate time.Time
+	cfCIDRsMu         sync.Mutex
+	cfCIDRsLogger     = logrus.WithField("middleware", "CloudflareRealIP")
+)
+
+var CloudflareRealIP = &realIP{
+	m: &Middleware{
+		withOptions: NewCloudflareRealIP,
+	},
+}
+
+func NewCloudflareRealIP(_ OptionsRaw, _ *ReverseProxy) (*Middleware, E.NestedError) {
+	cri := new(realIP)
+	cri.m = &Middleware{
+		impl: cri,
+		rewrite: func(r *Request) {
+			cidrs := tryFetchCFCIDR()
+			if cidrs != nil {
+				cri.From = cidrs
+			}
+			cri.setRealIP(r)
+		},
+	}
+	cri.realIPOpts = &realIPOpts{
+		Header:    "CF-Connecting-IP",
+		Recursive: true,
+	}
+	return cri.m, nil
+}
+
+func tryFetchCFCIDR() (cfCIDRs []*net.IPNet) {
+	if time.Since(cfCIDRsLastUpdate) < cfCIDRsUpdateInterval {
+		return
+	}
+
+	cfCIDRsMu.Lock()
+	defer cfCIDRsMu.Unlock()
+
+	if time.Since(cfCIDRsLastUpdate) < cfCIDRsUpdateInterval {
+		return
+	}
+
+	if common.IsTest {
+		cfCIDRs = []*net.IPNet{
+			{IP: net.IPv4(127, 0, 0, 1), Mask: net.IPv4Mask(255, 0, 0, 0)},
+			{IP: net.IPv4(10, 0, 0, 0), Mask: net.IPv4Mask(255, 0, 0, 0)},
+			{IP: net.IPv4(172, 16, 0, 0), Mask: net.IPv4Mask(255, 255, 0, 0)},
+			{IP: net.IPv4(192, 168, 0, 0), Mask: net.IPv4Mask(255, 255, 255, 0)},
+		}
+	} else {
+		cfCIDRs = make([]*net.IPNet, 0, 30)
+		err := errors.Join(
+			fetchUpdateCFIPRange(cfIPv4CIDRsEndpoint, cfCIDRs),
+			fetchUpdateCFIPRange(cfIPv6CIDRsEndpoint, cfCIDRs),
+		)
+		if err != nil {
+			cfCIDRsLastUpdate = time.Now().Add(-cfCIDRsUpdateRetryInterval - cfCIDRsUpdateInterval)
+			cfCIDRsLogger.Errorf("failed to update cloudflare range: %s, retry in %s", err, cfCIDRsUpdateRetryInterval)
+			return nil
+		}
+	}
+
+	cfCIDRsLastUpdate = time.Now()
+	cfCIDRsLogger.Debugf("cloudflare CIDR range updated")
+	return
+}
+
+func fetchUpdateCFIPRange(endpoint string, cfCIDRs []*net.IPNet) error {
+	resp, err := http.Get(endpoint)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	for _, line := range strings.Split(string(body), "\n") {
+		if line == "" {
+			continue
+		}
+		_, cidr, err := net.ParseCIDR(line)
+		if err != nil {
+			return fmt.Errorf("cloudflare responeded an invalid CIDR: %s", line)
+		} else {
+			cfCIDRs = append(cfCIDRs, cidr)
+		}
+	}
+
+	return nil
+}