refactor and organize code

2026-04-23 08:48:32 +02:00 · 2025-02-15 05:44:47 +08:00
parent 1af6dd9cf8
commit 18d258aaa2
169 changed files with 1020 additions and 755 deletions
--- a/internal/net/gphttp/middleware/cidr_whitelist.go
+++ b/internal/net/gphttp/middleware/cidr_whitelist.go
@@ -0,0 +1,82 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/go-playground/validator/v10"
+	gphttp "github.com/yusing/go-proxy/internal/net/gphttp"
+	"github.com/yusing/go-proxy/internal/net/types"
+	"github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
+)
+
+type (
+	cidrWhitelist struct {
+		CIDRWhitelistOpts
+		Tracer
+		cachedAddr F.Map[string, bool] // cache for trusted IPs
+	}
+	CIDRWhitelistOpts struct {
+		Allow      []*types.CIDR `validate:"min=1"`
+		StatusCode int           `json:"status_code" aliases:"status" validate:"omitempty,status_code"`
+		Message    string
+	}
+)
+
+var (
+	CIDRWhiteList         = NewMiddleware[cidrWhitelist]()
+	cidrWhitelistDefaults = CIDRWhitelistOpts{
+		Allow:      []*types.CIDR{},
+		StatusCode: http.StatusForbidden,
+		Message:    "IP not allowed",
+	}
+)
+
+func init() {
+	utils.MustRegisterValidation("status_code", func(fl validator.FieldLevel) bool {
+		statusCode := fl.Field().Int()
+		return gphttp.IsStatusCodeValid(int(statusCode))
+	})
+}
+
+// setup implements MiddlewareWithSetup.
+func (wl *cidrWhitelist) setup() {
+	wl.CIDRWhitelistOpts = cidrWhitelistDefaults
+	wl.cachedAddr = F.NewMapOf[string, bool]()
+}
+
+// before implements RequestModifier.
+func (wl *cidrWhitelist) before(w http.ResponseWriter, r *http.Request) bool {
+	return wl.checkIP(w, r)
+}
+
+// checkIP checks if the IP address is allowed.
+func (wl *cidrWhitelist) checkIP(w http.ResponseWriter, r *http.Request) bool {
+	var allow, ok bool
+	if allow, ok = wl.cachedAddr.Load(r.RemoteAddr); !ok {
+		ipStr, _, err := net.SplitHostPort(r.RemoteAddr)
+		if err != nil {
+			ipStr = r.RemoteAddr
+		}
+		ip := net.ParseIP(ipStr)
+		for _, cidr := range wl.CIDRWhitelistOpts.Allow {
+			if cidr.Contains(ip) {
+				wl.cachedAddr.Store(r.RemoteAddr, true)
+				allow = true
+				wl.AddTracef("client %s is allowed", ipStr).With("allowed CIDR", cidr)
+				break
+			}
+		}
+		if !allow {
+			wl.cachedAddr.Store(r.RemoteAddr, false)
+			wl.AddTracef("client %s is forbidden", ipStr).With("allowed CIDRs", wl.CIDRWhitelistOpts.Allow)
+		}
+	}
+	if !allow {
+		http.Error(w, wl.Message, wl.StatusCode)
+		return false
+	}
+
+	return true
+}
--- a/internal/net/gphttp/middleware/cidr_whitelist_test.go
+++ b/internal/net/gphttp/middleware/cidr_whitelist_test.go
@@ -0,0 +1,91 @@
+package middleware
+
+import (
+	_ "embed"
+	"net"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/utils"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+//go:embed test_data/cidr_whitelist_test.yml
+var testCIDRWhitelistCompose []byte
+var deny, accept *Middleware
+
+func TestCIDRWhitelistValidation(t *testing.T) {
+	const testMessage = "test-message"
+	t.Run("valid", func(t *testing.T) {
+		_, err := CIDRWhiteList.New(OptionsRaw{
+			"allow":   []string{"192.168.2.100/32"},
+			"message": testMessage,
+		})
+		ExpectNoError(t, err)
+		_, err = CIDRWhiteList.New(OptionsRaw{
+			"allow":   []string{"192.168.2.100/32"},
+			"message": testMessage,
+			"status":  403,
+		})
+		ExpectNoError(t, err)
+		_, err = CIDRWhiteList.New(OptionsRaw{
+			"allow":       []string{"192.168.2.100/32"},
+			"message":     testMessage,
+			"status_code": 403,
+		})
+		ExpectNoError(t, err)
+	})
+	t.Run("missing allow", func(t *testing.T) {
+		_, err := CIDRWhiteList.New(OptionsRaw{
+			"message": testMessage,
+		})
+		ExpectError(t, utils.ErrValidationError, err)
+	})
+	t.Run("invalid cidr", func(t *testing.T) {
+		_, err := CIDRWhiteList.New(OptionsRaw{
+			"allow":   []string{"192.168.2.100/123"},
+			"message": testMessage,
+		})
+		ExpectErrorT[*net.ParseError](t, err)
+	})
+	t.Run("invalid status code", func(t *testing.T) {
+		_, err := CIDRWhiteList.New(OptionsRaw{
+			"allow":       []string{"192.168.2.100/32"},
+			"status_code": 600,
+			"message":     testMessage,
+		})
+		ExpectError(t, utils.ErrValidationError, err)
+	})
+}
+
+func TestCIDRWhitelist(t *testing.T) {
+	errs := gperr.NewBuilder("")
+	mids := BuildMiddlewaresFromYAML("", testCIDRWhitelistCompose, errs)
+	ExpectNoError(t, errs.Error())
+	deny = mids["deny@file"]
+	accept = mids["accept@file"]
+	if deny == nil || accept == nil {
+		panic("bug occurred")
+	}
+
+	t.Run("deny", func(t *testing.T) {
+		t.Parallel()
+		for range 10 {
+			result, err := newMiddlewareTest(deny, nil)
+			ExpectNoError(t, err)
+			ExpectEqual(t, result.ResponseStatus, cidrWhitelistDefaults.StatusCode)
+			ExpectEqual(t, strings.TrimSpace(string(result.Data)), cidrWhitelistDefaults.Message)
+		}
+	})
+
+	t.Run("accept", func(t *testing.T) {
+		t.Parallel()
+		for range 10 {
+			result, err := newMiddlewareTest(accept, nil)
+			ExpectNoError(t, err)
+			ExpectEqual(t, result.ResponseStatus, http.StatusOK)
+		}
+	})
+}
--- a/internal/net/gphttp/middleware/cloudflare_real_ip.go
+++ b/internal/net/gphttp/middleware/cloudflare_real_ip.go
@@ -0,0 +1,127 @@
+package middleware
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/logging"
+	"github.com/yusing/go-proxy/internal/net/types"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
+)
+
+type cloudflareRealIP struct {
+	realIP    realIP
+	Recursive bool
+}
+
+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
+)
+
+var CloudflareRealIP = NewMiddleware[cloudflareRealIP]()
+
+// setup implements MiddlewareWithSetup.
+func (cri *cloudflareRealIP) setup() {
+	cri.realIP.RealIPOpts = RealIPOpts{
+		Header:    "Cf-Connecting-Ip",
+		Recursive: cri.Recursive,
+	}
+}
+
+// before implements RequestModifier.
+func (cri *cloudflareRealIP) before(w http.ResponseWriter, r *http.Request) bool {
+	cidrs := tryFetchCFCIDR()
+	if cidrs != nil {
+		cri.realIP.From = cidrs
+	}
+	return cri.realIP.before(w, r)
+}
+
+func (cri *cloudflareRealIP) enableTrace() {
+	cri.realIP.enableTrace()
+}
+
+func (cri *cloudflareRealIP) getTracer() *Tracer {
+	return cri.realIP.getTracer()
+}
+
+func tryFetchCFCIDR() (cfCIDRs []*types.CIDR) {
+	if time.Since(cfCIDRsLastUpdate) < cfCIDRsUpdateInterval {
+		return
+	}
+
+	cfCIDRsMu.Lock()
+	defer cfCIDRsMu.Unlock()
+
+	if time.Since(cfCIDRsLastUpdate) < cfCIDRsUpdateInterval {
+		return
+	}
+
+	if common.IsTest {
+		cfCIDRs = []*types.CIDR{
+			{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([]*types.CIDR, 0, 30)
+		err := errors.Join(
+			fetchUpdateCFIPRange(cfIPv4CIDRsEndpoint, &cfCIDRs),
+			fetchUpdateCFIPRange(cfIPv6CIDRsEndpoint, &cfCIDRs),
+		)
+		if err != nil {
+			cfCIDRsLastUpdate = time.Now().Add(-cfCIDRsUpdateRetryInterval - cfCIDRsUpdateInterval)
+			logging.Err(err).Msg("failed to update cloudflare range, retry in " + strutils.FormatDuration(cfCIDRsUpdateRetryInterval))
+			return nil
+		}
+		if len(cfCIDRs) == 0 {
+			logging.Warn().Msg("cloudflare CIDR range is empty")
+		}
+	}
+
+	cfCIDRsLastUpdate = time.Now()
+	logging.Info().Msg("cloudflare CIDR range updated")
+	return
+}
+
+func fetchUpdateCFIPRange(endpoint string, cfCIDRs *[]*types.CIDR) 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 strutils.SplitLine(string(body)) {
+		if line == "" {
+			continue
+		}
+		_, cidr, err := net.ParseCIDR(line)
+		if err != nil {
+			return fmt.Errorf("cloudflare responeded an invalid CIDR: %s", line)
+		}
+
+		*cfCIDRs = append(*cfCIDRs, (*types.CIDR)(cidr))
+	}
+
+	return nil
+}
--- a/internal/net/gphttp/middleware/custom_error_page.go
+++ b/internal/net/gphttp/middleware/custom_error_page.go
@@ -0,0 +1,80 @@
+package middleware
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/logging"
+	gphttp "github.com/yusing/go-proxy/internal/net/gphttp"
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/gphttp/middleware/errorpage"
+)
+
+type customErrorPage struct{}
+
+var CustomErrorPage = NewMiddleware[customErrorPage]()
+
+const StaticFilePathPrefix = "/$gperrorpage/"
+
+// before implements RequestModifier.
+func (customErrorPage) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	return !ServeStaticErrorPageFile(w, r)
+}
+
+// modifyResponse implements ResponseModifier.
+func (customErrorPage) modifyResponse(resp *http.Response) error {
+	// only handles non-success status code and html/plain content type
+	contentType := gphttp.GetContentType(resp.Header)
+	if !gphttp.IsSuccess(resp.StatusCode) && (contentType.IsHTML() || contentType.IsPlainText()) {
+		errorPage, ok := errorpage.GetErrorPageByStatus(resp.StatusCode)
+		if ok {
+			logging.Debug().Msgf("error page for status %d loaded", resp.StatusCode)
+			_, _ = io.Copy(io.Discard, resp.Body) // drain the original body
+			resp.Body.Close()
+			resp.Body = io.NopCloser(bytes.NewReader(errorPage))
+			resp.ContentLength = int64(len(errorPage))
+			resp.Header.Set(httpheaders.HeaderContentLength, strconv.Itoa(len(errorPage)))
+			resp.Header.Set(httpheaders.HeaderContentType, "text/html; charset=utf-8")
+		} else {
+			logging.Error().Msgf("unable to load error page for status %d", resp.StatusCode)
+		}
+		return nil
+	}
+	return nil
+}
+
+func ServeStaticErrorPageFile(w http.ResponseWriter, r *http.Request) (served bool) {
+	path := r.URL.Path
+	if path != "" && path[0] != '/' {
+		path = "/" + path
+	}
+	if strings.HasPrefix(path, StaticFilePathPrefix) {
+		filename := path[len(StaticFilePathPrefix):]
+		file, ok := errorpage.GetStaticFile(filename)
+		if !ok {
+			logging.Error().Msg("unable to load resource " + filename)
+			return false
+		}
+		ext := filepath.Ext(filename)
+		switch ext {
+		case ".html":
+			w.Header().Set(httpheaders.HeaderContentType, "text/html; charset=utf-8")
+		case ".js":
+			w.Header().Set(httpheaders.HeaderContentType, "application/javascript; charset=utf-8")
+		case ".css":
+			w.Header().Set(httpheaders.HeaderContentType, "text/css; charset=utf-8")
+		default:
+			logging.Error().Msgf("unexpected file type %q for %s", ext, filename)
+		}
+		if _, err := w.Write(file); err != nil {
+			logging.Err(err).Msg("unable to write resource " + filename)
+			http.Error(w, "Error page failure", http.StatusInternalServerError)
+		}
+		return true
+	}
+	return false
+}
--- a/internal/net/gphttp/middleware/errorpage/error_page.go
+++ b/internal/net/gphttp/middleware/errorpage/error_page.go
@@ -0,0 +1,96 @@
+package errorpage
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"sync"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/logging"
+	"github.com/yusing/go-proxy/internal/task"
+	U "github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
+	W "github.com/yusing/go-proxy/internal/watcher"
+	"github.com/yusing/go-proxy/internal/watcher/events"
+)
+
+const errPagesBasePath = common.ErrorPagesBasePath
+
+var (
+	setupOnce      sync.Once
+	dirWatcher     W.Watcher
+	fileContentMap = F.NewMapOf[string, []byte]()
+)
+
+func setup() {
+	t := task.RootTask("error_page", false)
+	dirWatcher = W.NewDirectoryWatcher(t, errPagesBasePath)
+	loadContent()
+	go watchDir()
+}
+
+func GetStaticFile(filename string) ([]byte, bool) {
+	setupOnce.Do(setup)
+	return fileContentMap.Load(filename)
+}
+
+// try <statusCode>.html -> 404.html -> not ok.
+func GetErrorPageByStatus(statusCode int) (content []byte, ok bool) {
+	content, ok = GetStaticFile(fmt.Sprintf("%d.html", statusCode))
+	if !ok && statusCode != 404 {
+		return fileContentMap.Load("404.html")
+	}
+	return
+}
+
+func loadContent() {
+	files, err := U.ListFiles(errPagesBasePath, 0)
+	if err != nil {
+		logging.Err(err).Msg("failed to list error page resources")
+		return
+	}
+	for _, file := range files {
+		if fileContentMap.Has(file) {
+			continue
+		}
+		content, err := os.ReadFile(file)
+		if err != nil {
+			logging.Warn().Err(err).Msgf("failed to read error page resource %s", file)
+			continue
+		}
+		file = path.Base(file)
+		logging.Info().Msgf("error page resource %s loaded", file)
+		fileContentMap.Store(file, content)
+	}
+}
+
+func watchDir() {
+	eventCh, errCh := dirWatcher.Events(task.RootContext())
+	for {
+		select {
+		case <-task.RootContextCanceled():
+			return
+		case event, ok := <-eventCh:
+			if !ok {
+				return
+			}
+			filename := event.ActorName
+			switch event.Action {
+			case events.ActionFileWritten:
+				fileContentMap.Delete(filename)
+				loadContent()
+			case events.ActionFileDeleted:
+				fileContentMap.Delete(filename)
+				logging.Warn().Msgf("error page resource %s deleted", filename)
+			case events.ActionFileRenamed:
+				logging.Warn().Msgf("error page resource %s deleted", filename)
+				fileContentMap.Delete(filename)
+				loadContent()
+			}
+		case err := <-errCh:
+			gperr.LogError("error watching error page directory", err)
+		}
+	}
+}
--- a/internal/net/gphttp/middleware/metrics_logger/metrics_logger.go
+++ b/internal/net/gphttp/middleware/metrics_logger/metrics_logger.go
@@ -0,0 +1,44 @@
+package metricslogger
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/metrics"
+)
+
+type MetricsLogger struct {
+	ServiceName string `json:"service_name"`
+}
+
+func NewMetricsLogger(serviceName string) *MetricsLogger {
+	return &MetricsLogger{serviceName}
+}
+
+func (m *MetricsLogger) GetHandler(next http.Handler) http.HandlerFunc {
+	return func(rw http.ResponseWriter, req *http.Request) {
+		m.ServeHTTP(rw, req, next.ServeHTTP)
+	}
+}
+
+func (m *MetricsLogger) ServeHTTP(rw http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
+	visitorIP, _, err := net.SplitHostPort(req.RemoteAddr)
+	if err != nil {
+		visitorIP = req.RemoteAddr
+	}
+
+	// req.RemoteAddr had been modified by middleware (if any)
+	lbls := &metrics.HTTPRouteMetricLabels{
+		Service: m.ServiceName,
+		Method:  req.Method,
+		Host:    req.Host,
+		Visitor: visitorIP,
+		Path:    req.URL.Path,
+	}
+
+	next.ServeHTTP(newHTTPMetricLogger(rw, lbls), req)
+}
+
+func (m *MetricsLogger) ResetMetrics() {
+	metrics.GetRouteMetrics().UnregisterService(m.ServiceName)
+}
--- a/internal/net/gphttp/middleware/metrics_logger/metrics_response_writer.go
+++ b/internal/net/gphttp/middleware/metrics_logger/metrics_response_writer.go
@@ -0,0 +1,47 @@
+package metricslogger
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/yusing/go-proxy/internal/metrics"
+)
+
+type httpMetricLogger struct {
+	http.ResponseWriter
+	timestamp time.Time
+	labels    *metrics.HTTPRouteMetricLabels
+}
+
+// WriteHeader implements http.ResponseWriter.
+func (l *httpMetricLogger) WriteHeader(status int) {
+	l.ResponseWriter.WriteHeader(status)
+	duration := time.Since(l.timestamp)
+	go func() {
+		m := metrics.GetRouteMetrics()
+		m.HTTPReqTotal.Inc()
+		m.HTTPReqElapsed.With(l.labels).Set(float64(duration.Milliseconds()))
+
+		// ignore 1xx
+		switch {
+		case status >= 500:
+			m.HTTP5xx.With(l.labels).Inc()
+		case status >= 400:
+			m.HTTP4xx.With(l.labels).Inc()
+		case status >= 200:
+			m.HTTP2xx3xx.With(l.labels).Inc()
+		}
+	}()
+}
+
+func (l *httpMetricLogger) Unwrap() http.ResponseWriter {
+	return l.ResponseWriter
+}
+
+func newHTTPMetricLogger(w http.ResponseWriter, labels *metrics.HTTPRouteMetricLabels) *httpMetricLogger {
+	return &httpMetricLogger{
+		ResponseWriter: w,
+		timestamp:      time.Now(),
+		labels:         labels,
+	}
+}
--- a/internal/net/gphttp/middleware/middleware.go
+++ b/internal/net/gphttp/middleware/middleware.go
@@ -0,0 +1,237 @@
+package middleware
+
+import (
+	"encoding/json"
+	"net/http"
+	"reflect"
+	"sort"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/logging"
+	gphttp "github.com/yusing/go-proxy/internal/net/gphttp"
+	"github.com/yusing/go-proxy/internal/net/gphttp/reverseproxy"
+	"github.com/yusing/go-proxy/internal/utils"
+)
+
+type (
+	Error = gperr.Error
+
+	ReverseProxy = reverseproxy.ReverseProxy
+	ProxyRequest = reverseproxy.ProxyRequest
+
+	ImplNewFunc = func() any
+	OptionsRaw  = map[string]any
+
+	Middleware struct {
+		name      string
+		construct ImplNewFunc
+		impl      any
+		// priority is only applied for ReverseProxy.
+		//
+		// Middleware compose follows the order of the slice
+		//
+		// Default is 10, 0 is the highest
+		priority int
+	}
+	ByPriority []*Middleware
+
+	RequestModifier interface {
+		before(w http.ResponseWriter, r *http.Request) (proceed bool)
+	}
+	ResponseModifier             interface{ modifyResponse(r *http.Response) error }
+	MiddlewareWithSetup          interface{ setup() }
+	MiddlewareFinalizer          interface{ finalize() }
+	MiddlewareFinalizerWithError interface {
+		finalize() error
+	}
+	MiddlewareWithTracer interface {
+		enableTrace()
+		getTracer() *Tracer
+	}
+)
+
+const DefaultPriority = 10
+
+func (m ByPriority) Len() int           { return len(m) }
+func (m ByPriority) Swap(i, j int)      { m[i], m[j] = m[j], m[i] }
+func (m ByPriority) Less(i, j int) bool { return m[i].priority < m[j].priority }
+
+func NewMiddleware[ImplType any]() *Middleware {
+	// type check
+	t := any(new(ImplType))
+	switch t.(type) {
+	case RequestModifier:
+	case ResponseModifier:
+	default:
+		panic("must implement RequestModifier or ResponseModifier")
+	}
+	_, hasFinializer := t.(MiddlewareFinalizer)
+	_, hasFinializerWithError := t.(MiddlewareFinalizerWithError)
+	if hasFinializer && hasFinializerWithError {
+		panic("MiddlewareFinalizer and MiddlewareFinalizerWithError are mutually exclusive")
+	}
+	return &Middleware{
+		name:      strings.ToLower(reflect.TypeFor[ImplType]().Name()),
+		construct: func() any { return new(ImplType) },
+	}
+}
+
+func (m *Middleware) enableTrace() {
+	if tracer, ok := m.impl.(MiddlewareWithTracer); ok {
+		tracer.enableTrace()
+		logging.Debug().Msgf("middleware %s enabled trace", m.name)
+	}
+}
+
+func (m *Middleware) getTracer() *Tracer {
+	if tracer, ok := m.impl.(MiddlewareWithTracer); ok {
+		return tracer.getTracer()
+	}
+	return nil
+}
+
+func (m *Middleware) setParent(parent *Middleware) {
+	if tracer := m.getTracer(); tracer != nil {
+		tracer.SetParent(parent.getTracer())
+	}
+}
+
+func (m *Middleware) setup() {
+	if setup, ok := m.impl.(MiddlewareWithSetup); ok {
+		setup.setup()
+	}
+}
+
+func (m *Middleware) apply(optsRaw OptionsRaw) gperr.Error {
+	if len(optsRaw) == 0 {
+		return nil
+	}
+	priority, ok := optsRaw["priority"].(int)
+	if ok {
+		m.priority = priority
+		// remove priority for deserialization, restore later
+		delete(optsRaw, "priority")
+		defer func() {
+			optsRaw["priority"] = priority
+		}()
+	} else {
+		m.priority = DefaultPriority
+	}
+	return utils.Deserialize(optsRaw, m.impl)
+}
+
+func (m *Middleware) finalize() error {
+	if finalizer, ok := m.impl.(MiddlewareFinalizer); ok {
+		finalizer.finalize()
+		return nil
+	}
+	if finalizer, ok := m.impl.(MiddlewareFinalizerWithError); ok {
+		return finalizer.finalize()
+	}
+	return nil
+}
+
+func (m *Middleware) New(optsRaw OptionsRaw) (*Middleware, gperr.Error) {
+	if m.construct == nil { // likely a middleware from compose
+		if len(optsRaw) != 0 {
+			return nil, gperr.New("additional options not allowed for middleware ").Subject(m.name)
+		}
+		return m, nil
+	}
+	mid := &Middleware{name: m.name, impl: m.construct()}
+	mid.setup()
+	if err := mid.apply(optsRaw); err != nil {
+		return nil, err
+	}
+	if err := mid.finalize(); err != nil {
+		return nil, gperr.Wrap(err)
+	}
+	return mid, nil
+}
+
+func (m *Middleware) Name() string {
+	return m.name
+}
+
+func (m *Middleware) String() string {
+	return m.name
+}
+
+func (m *Middleware) MarshalJSON() ([]byte, error) {
+	return json.MarshalIndent(map[string]any{
+		"name":     m.name,
+		"options":  m.impl,
+		"priority": m.priority,
+	}, "", "  ")
+}
+
+func (m *Middleware) ModifyRequest(next http.HandlerFunc, w http.ResponseWriter, r *http.Request) {
+	if exec, ok := m.impl.(RequestModifier); ok {
+		if proceed := exec.before(w, r); !proceed {
+			return
+		}
+	}
+	next(w, r)
+}
+
+func (m *Middleware) ModifyResponse(resp *http.Response) error {
+	if exec, ok := m.impl.(ResponseModifier); ok {
+		return exec.modifyResponse(resp)
+	}
+	return nil
+}
+
+func (m *Middleware) ServeHTTP(next http.HandlerFunc, w http.ResponseWriter, r *http.Request) {
+	if exec, ok := m.impl.(ResponseModifier); ok {
+		w = gphttp.NewModifyResponseWriter(w, r, func(resp *http.Response) error {
+			return exec.modifyResponse(resp)
+		})
+	}
+	if exec, ok := m.impl.(RequestModifier); ok {
+		if proceed := exec.before(w, r); !proceed {
+			return
+		}
+	}
+	next(w, r)
+}
+
+func PatchReverseProxy(rp *ReverseProxy, middlewaresMap map[string]OptionsRaw) (err gperr.Error) {
+	var middlewares []*Middleware
+	middlewares, err = compileMiddlewares(middlewaresMap)
+	if err != nil {
+		return
+	}
+	patchReverseProxy(rp, middlewares)
+	return
+}
+
+func patchReverseProxy(rp *ReverseProxy, middlewares []*Middleware) {
+	sort.Sort(ByPriority(middlewares))
+	middlewares = append([]*Middleware{newSetUpstreamHeaders(rp)}, middlewares...)
+
+	mid := NewMiddlewareChain(rp.TargetName, middlewares)
+
+	if before, ok := mid.impl.(RequestModifier); ok {
+		next := rp.HandlerFunc
+		rp.HandlerFunc = func(w http.ResponseWriter, r *http.Request) {
+			if proceed := before.before(w, r); proceed {
+				next(w, r)
+			}
+		}
+	}
+
+	if mr, ok := mid.impl.(ResponseModifier); ok {
+		if rp.ModifyResponse != nil {
+			ori := rp.ModifyResponse
+			rp.ModifyResponse = func(res *http.Response) error {
+				if err := mr.modifyResponse(res); err != nil {
+					return err
+				}
+				return ori(res)
+			}
+		} else {
+			rp.ModifyResponse = mr.modifyResponse
+		}
+	}
+}
--- a/internal/net/gphttp/middleware/middleware_builder.go
+++ b/internal/net/gphttp/middleware/middleware_builder.go
@@ -0,0 +1,107 @@
+package middleware
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"sort"
+
+	"github.com/yusing/go-proxy/internal/gperr"
+	"gopkg.in/yaml.v3"
+)
+
+var ErrMissingMiddlewareUse = gperr.New("missing middleware 'use' field")
+
+func BuildMiddlewaresFromComposeFile(filePath string, eb *gperr.Builder) map[string]*Middleware {
+	fileContent, err := os.ReadFile(filePath)
+	if err != nil {
+		eb.Add(err)
+		return nil
+	}
+	return BuildMiddlewaresFromYAML(path.Base(filePath), fileContent, eb)
+}
+
+func BuildMiddlewaresFromYAML(source string, data []byte, eb *gperr.Builder) map[string]*Middleware {
+	var rawMap map[string][]map[string]any
+	err := yaml.Unmarshal(data, &rawMap)
+	if err != nil {
+		eb.Add(err)
+		return nil
+	}
+	middlewares := make(map[string]*Middleware)
+	for name, defs := range rawMap {
+		chain, err := BuildMiddlewareFromChainRaw(name, defs)
+		if err != nil {
+			eb.Add(err.Subject(source))
+		} else {
+			middlewares[name+"@file"] = chain
+		}
+	}
+	return middlewares
+}
+
+func compileMiddlewares(middlewaresMap map[string]OptionsRaw) ([]*Middleware, gperr.Error) {
+	middlewares := make([]*Middleware, 0, len(middlewaresMap))
+
+	errs := gperr.NewBuilder("middlewares compile error")
+	invalidOpts := gperr.NewBuilder("options compile error")
+
+	for name, opts := range middlewaresMap {
+		m, err := Get(name)
+		if err != nil {
+			errs.Add(err)
+			continue
+		}
+
+		m, err = m.New(opts)
+		if err != nil {
+			invalidOpts.Add(err.Subject(name))
+			continue
+		}
+		middlewares = append(middlewares, m)
+	}
+
+	if invalidOpts.HasError() {
+		errs.Add(invalidOpts.Error())
+	}
+	sort.Sort(ByPriority(middlewares))
+	return middlewares, errs.Error()
+}
+
+func BuildMiddlewareFromMap(name string, middlewaresMap map[string]OptionsRaw) (*Middleware, gperr.Error) {
+	compiled, err := compileMiddlewares(middlewaresMap)
+	if err != nil {
+		return nil, err
+	}
+	return NewMiddlewareChain(name, compiled), nil
+}
+
+// TODO: check conflict or duplicates.
+func BuildMiddlewareFromChainRaw(name string, defs []map[string]any) (*Middleware, gperr.Error) {
+	chainErr := gperr.NewBuilder("")
+	chain := make([]*Middleware, 0, len(defs))
+	for i, def := range defs {
+		if def["use"] == nil || def["use"] == "" {
+			chainErr.Add(ErrMissingMiddlewareUse.Subjectf("%s[%d]", name, i))
+			continue
+		}
+		baseName := def["use"].(string)
+		base, err := Get(baseName)
+		if err != nil {
+			chainErr.Add(err.Subjectf("%s[%d]", name, i))
+			continue
+		}
+		delete(def, "use")
+		m, err := base.New(def)
+		if err != nil {
+			chainErr.Add(err.Subjectf("%s[%d]", name, i))
+			continue
+		}
+		m.name = fmt.Sprintf("%s[%d]", name, i)
+		chain = append(chain, m)
+	}
+	if chainErr.HasError() {
+		return nil, chainErr.Error()
+	}
+	return NewMiddlewareChain(name, chain), nil
+}
--- a/internal/net/gphttp/middleware/middleware_builder_test.go
+++ b/internal/net/gphttp/middleware/middleware_builder_test.go
@@ -0,0 +1,22 @@
+package middleware
+
+import (
+	_ "embed"
+	"encoding/json"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/gperr"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+//go:embed test_data/middleware_compose.yml
+var testMiddlewareCompose []byte
+
+func TestBuild(t *testing.T) {
+	errs := gperr.NewBuilder("")
+	middlewares := BuildMiddlewaresFromYAML("", testMiddlewareCompose, errs)
+	ExpectNoError(t, errs.Error())
+	Must(json.MarshalIndent(middlewares, "", "  "))
+	// t.Log(string(data))
+	// TODO: test
+}
--- a/internal/net/gphttp/middleware/middleware_chain.go
+++ b/internal/net/gphttp/middleware/middleware_chain.go
@@ -0,0 +1,61 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/gperr"
+)
+
+type middlewareChain struct {
+	befores  []RequestModifier
+	modResps []ResponseModifier
+}
+
+// TODO: check conflict or duplicates.
+func NewMiddlewareChain(name string, chain []*Middleware) *Middleware {
+	chainMid := &middlewareChain{befores: []RequestModifier{}, modResps: []ResponseModifier{}}
+	m := &Middleware{name: name, impl: chainMid}
+
+	for _, comp := range chain {
+		if before, ok := comp.impl.(RequestModifier); ok {
+			chainMid.befores = append(chainMid.befores, before)
+		}
+		if mr, ok := comp.impl.(ResponseModifier); ok {
+			chainMid.modResps = append(chainMid.modResps, mr)
+		}
+		comp.setParent(m)
+	}
+
+	if common.IsDebug {
+		for _, child := range chain {
+			child.enableTrace()
+		}
+		m.enableTrace()
+	}
+	return m
+}
+
+// before implements RequestModifier.
+func (m *middlewareChain) before(w http.ResponseWriter, r *http.Request) (proceedNext bool) {
+	for _, b := range m.befores {
+		if proceedNext = b.before(w, r); !proceedNext {
+			return false
+		}
+	}
+	return true
+}
+
+// modifyResponse implements ResponseModifier.
+func (m *middlewareChain) modifyResponse(resp *http.Response) error {
+	if len(m.modResps) == 0 {
+		return nil
+	}
+	errs := gperr.NewBuilder("modify response errors")
+	for i, mr := range m.modResps {
+		if err := mr.modifyResponse(resp); err != nil {
+			errs.Add(gperr.Wrap(err).Subjectf("%d", i))
+		}
+	}
+	return errs.Error()
+}
--- a/internal/net/gphttp/middleware/middleware_test.go
+++ b/internal/net/gphttp/middleware/middleware_test.go
@@ -0,0 +1,37 @@
+package middleware
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+	"testing"
+
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+type testPriority struct {
+	Value int `json:"value"`
+}
+
+var test = NewMiddleware[testPriority]()
+
+func (t testPriority) before(w http.ResponseWriter, r *http.Request) bool {
+	w.Header().Add("Test-Value", strconv.Itoa(t.Value))
+	return true
+}
+
+func TestMiddlewarePriority(t *testing.T) {
+	priorities := []int{4, 7, 9, 0}
+	chain := make([]*Middleware, len(priorities))
+	for i, p := range priorities {
+		mid, err := test.New(OptionsRaw{
+			"priority": p,
+			"value":    i,
+		})
+		ExpectNoError(t, err)
+		chain[i] = mid
+	}
+	res, err := newMiddlewaresTest(chain, nil)
+	ExpectNoError(t, err)
+	ExpectEqual(t, strings.Join(res.ResponseHeaders["Test-Value"], ","), "3,0,1,2")
+}
--- a/internal/net/gphttp/middleware/middlewares.go
+++ b/internal/net/gphttp/middleware/middlewares.go
@@ -0,0 +1,104 @@
+package middleware
+
+import (
+	"path"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/logging"
+	"github.com/yusing/go-proxy/internal/utils"
+	"github.com/yusing/go-proxy/internal/utils/strutils"
+)
+
+// snakes and cases will be stripped on `Get`
+// so keys are lowercase without snake.
+var allMiddlewares = map[string]*Middleware{
+	"redirecthttp": RedirectHTTP,
+
+	"oidc": OIDC,
+
+	"request":        ModifyRequest,
+	"modifyrequest":  ModifyRequest,
+	"response":       ModifyResponse,
+	"modifyresponse": ModifyResponse,
+	"setxforwarded":  SetXForwarded,
+	"hidexforwarded": HideXForwarded,
+
+	"errorpage":       CustomErrorPage,
+	"customerrorpage": CustomErrorPage,
+
+	"realip":           RealIP,
+	"cloudflarerealip": CloudflareRealIP,
+
+	"cidrwhitelist": CIDRWhiteList,
+	"ratelimit":     RateLimiter,
+}
+
+var (
+	ErrUnknownMiddleware    = gperr.New("unknown middleware")
+	ErrDuplicatedMiddleware = gperr.New("duplicated middleware")
+)
+
+func Get(name string) (*Middleware, Error) {
+	middleware, ok := allMiddlewares[strutils.ToLowerNoSnake(name)]
+	if !ok {
+		return nil, ErrUnknownMiddleware.
+			Subject(name).
+			Withf(strutils.DoYouMean(utils.NearestField(name, allMiddlewares)))
+	}
+	return middleware, nil
+}
+
+func All() map[string]*Middleware {
+	return allMiddlewares
+}
+
+func LoadComposeFiles() {
+	errs := gperr.NewBuilder("middleware compile errors")
+	middlewareDefs, err := utils.ListFiles(common.MiddlewareComposeBasePath, 0)
+	if err != nil {
+		logging.Err(err).Msg("failed to list middleware definitions")
+		return
+	}
+	for _, defFile := range middlewareDefs {
+		voidErrs := gperr.NewBuilder("") // ignore these errors, will be added in next step
+		mws := BuildMiddlewaresFromComposeFile(defFile, voidErrs)
+		if len(mws) == 0 {
+			continue
+		}
+		for name, m := range mws {
+			name = strutils.ToLowerNoSnake(name)
+			if _, ok := allMiddlewares[name]; ok {
+				errs.Add(ErrDuplicatedMiddleware.Subject(name))
+				continue
+			}
+			allMiddlewares[name] = m
+			logging.Info().
+				Str("src", path.Base(defFile)).
+				Str("name", name).
+				Msg("middleware loaded")
+		}
+	}
+	// build again to resolve cross references
+	for _, defFile := range middlewareDefs {
+		mws := BuildMiddlewaresFromComposeFile(defFile, errs)
+		if len(mws) == 0 {
+			continue
+		}
+		for name, m := range mws {
+			name = strutils.ToLowerNoSnake(name)
+			if _, ok := allMiddlewares[name]; ok {
+				// already loaded above
+				continue
+			}
+			allMiddlewares[name] = m
+			logging.Info().
+				Str("src", path.Base(defFile)).
+				Str("name", name).
+				Msg("middleware loaded")
+		}
+	}
+	if errs.HasError() {
+		gperr.LogError(errs.About(), errs.Error())
+	}
+}
--- a/internal/net/gphttp/middleware/modify_request.go
+++ b/internal/net/gphttp/middleware/modify_request.go
@@ -0,0 +1,91 @@
+package middleware
+
+import (
+	"net/http"
+	"path/filepath"
+	"strings"
+)
+
+type (
+	modifyRequest struct {
+		ModifyRequestOpts
+		Tracer
+	}
+	// order: add_prefix -> set_headers -> add_headers -> hide_headers
+	ModifyRequestOpts struct {
+		SetHeaders  map[string]string
+		AddHeaders  map[string]string
+		HideHeaders []string
+		AddPrefix   string
+
+		needVarSubstitution bool
+	}
+)
+
+var ModifyRequest = NewMiddleware[modifyRequest]()
+
+// finalize implements MiddlewareFinalizer.
+func (mr *ModifyRequestOpts) finalize() {
+	mr.checkVarSubstitution()
+}
+
+// before implements RequestModifier.
+func (mr *modifyRequest) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	mr.AddTraceRequest("before modify request", r)
+
+	mr.addPrefix(r, nil, r.URL.Path)
+	mr.modifyHeaders(r, nil, r.Header)
+	mr.AddTraceRequest("after modify request", r)
+	return true
+}
+
+func (mr *ModifyRequestOpts) checkVarSubstitution() {
+	for _, m := range []map[string]string{mr.SetHeaders, mr.AddHeaders} {
+		for _, v := range m {
+			if strings.ContainsRune(v, '$') {
+				mr.needVarSubstitution = true
+				return
+			}
+		}
+	}
+}
+
+func (mr *ModifyRequestOpts) modifyHeaders(req *http.Request, resp *http.Response, headers http.Header) {
+	if !mr.needVarSubstitution {
+		for k, v := range mr.SetHeaders {
+			if req != nil && strings.EqualFold(k, "host") {
+				defer func() {
+					req.Host = v
+				}()
+			}
+			headers[k] = []string{v}
+		}
+		for k, v := range mr.AddHeaders {
+			headers[k] = append(headers[k], v)
+		}
+	} else {
+		for k, v := range mr.SetHeaders {
+			if req != nil && strings.EqualFold(k, "host") {
+				defer func() {
+					req.Host = varReplace(req, resp, v)
+				}()
+			}
+			headers[k] = []string{varReplace(req, resp, v)}
+		}
+		for k, v := range mr.AddHeaders {
+			headers[k] = append(headers[k], varReplace(req, resp, v))
+		}
+	}
+
+	for _, k := range mr.HideHeaders {
+		delete(headers, k)
+	}
+}
+
+func (mr *modifyRequest) addPrefix(r *http.Request, _ *http.Response, path string) {
+	if len(mr.AddPrefix) == 0 {
+		return
+	}
+
+	r.URL.Path = filepath.Join(mr.AddPrefix, path)
+}
--- a/internal/net/gphttp/middleware/modify_request_test.go
+++ b/internal/net/gphttp/middleware/modify_request_test.go
@@ -0,0 +1,145 @@
+package middleware
+
+import (
+	"bytes"
+	"net"
+	"net/http"
+	"slices"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/net/types"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestModifyRequest(t *testing.T) {
+	opts := OptionsRaw{
+		"set_headers": map[string]string{
+			"User-Agent":                 "go-proxy/v0.5.0",
+			"Host":                       VarUpstreamAddr,
+			"X-Test-Req-Method":          VarRequestMethod,
+			"X-Test-Req-Scheme":          VarRequestScheme,
+			"X-Test-Req-Host":            VarRequestHost,
+			"X-Test-Req-Port":            VarRequestPort,
+			"X-Test-Req-Addr":            VarRequestAddr,
+			"X-Test-Req-Path":            VarRequestPath,
+			"X-Test-Req-Query":           VarRequestQuery,
+			"X-Test-Req-Url":             VarRequestURL,
+			"X-Test-Req-Uri":             VarRequestURI,
+			"X-Test-Req-Content-Type":    VarRequestContentType,
+			"X-Test-Req-Content-Length":  VarRequestContentLen,
+			"X-Test-Remote-Host":         VarRemoteHost,
+			"X-Test-Remote-Port":         VarRemotePort,
+			"X-Test-Remote-Addr":         VarRemoteAddr,
+			"X-Test-Upstream-Scheme":     VarUpstreamScheme,
+			"X-Test-Upstream-Host":       VarUpstreamHost,
+			"X-Test-Upstream-Port":       VarUpstreamPort,
+			"X-Test-Upstream-Addr":       VarUpstreamAddr,
+			"X-Test-Upstream-Url":        VarUpstreamURL,
+			"X-Test-Header-Content-Type": "$header(Content-Type)",
+			"X-Test-Arg-Arg_1":           "$arg(arg_1)",
+		},
+		"add_headers":  map[string]string{"Accept-Encoding": "test-value"},
+		"hide_headers": []string{"Accept"},
+	}
+
+	t.Run("set_options", func(t *testing.T) {
+		mr, err := ModifyRequest.New(opts)
+		ExpectNoError(t, err)
+		ExpectDeepEqual(t, mr.impl.(*modifyRequest).SetHeaders, opts["set_headers"].(map[string]string))
+		ExpectDeepEqual(t, mr.impl.(*modifyRequest).AddHeaders, opts["add_headers"].(map[string]string))
+		ExpectDeepEqual(t, mr.impl.(*modifyRequest).HideHeaders, opts["hide_headers"].([]string))
+	})
+
+	t.Run("request_headers", func(t *testing.T) {
+		reqURL := types.MustParseURL("https://my.app/?arg_1=b")
+		upstreamURL := types.MustParseURL("http://test.example.com")
+		result, err := newMiddlewareTest(ModifyRequest, &testArgs{
+			middlewareOpt: opts,
+			reqURL:        reqURL,
+			upstreamURL:   upstreamURL,
+			body:          bytes.Repeat([]byte("a"), 100),
+			headers: http.Header{
+				"Content-Type": []string{"application/json"},
+			},
+		})
+		ExpectNoError(t, err)
+		ExpectEqual(t, result.RequestHeaders.Get("User-Agent"), "go-proxy/v0.5.0")
+		ExpectEqual(t, result.RequestHeaders.Get("Host"), "test.example.com")
+		ExpectTrue(t, slices.Contains(result.RequestHeaders.Values("Accept-Encoding"), "test-value"))
+		ExpectEqual(t, result.RequestHeaders.Get("Accept"), "")
+
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Method"), "GET")
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Scheme"), reqURL.Scheme)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Host"), reqURL.Hostname())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Port"), reqURL.Port())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Addr"), reqURL.Host)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Path"), reqURL.Path)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Query"), reqURL.RawQuery)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Url"), reqURL.String())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Uri"), reqURL.RequestURI())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Content-Type"), "application/json")
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Content-Length"), "100")
+
+		remoteHost, remotePort, _ := net.SplitHostPort(result.RemoteAddr)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Remote-Host"), remoteHost)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Remote-Port"), remotePort)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Remote-Addr"), result.RemoteAddr)
+
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Upstream-Scheme"), upstreamURL.Scheme)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Upstream-Host"), upstreamURL.Hostname())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Upstream-Port"), upstreamURL.Port())
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Upstream-Addr"), upstreamURL.Host)
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Upstream-Url"), upstreamURL.String())
+
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Header-Content-Type"), "application/json")
+
+		ExpectEqual(t, result.RequestHeaders.Get("X-Test-Arg-Arg_1"), "b")
+	})
+
+	t.Run("add_prefix", func(t *testing.T) {
+		tests := []struct {
+			name         string
+			path         string
+			expectedPath string
+			upstreamURL  string
+			addPrefix    string
+		}{
+			{
+				name:         "no prefix",
+				path:         "/foo",
+				expectedPath: "/foo",
+				upstreamURL:  "http://test.example.com",
+			},
+			{
+				name:         "slash only",
+				path:         "/",
+				expectedPath: "/",
+				upstreamURL:  "http://test.example.com",
+				addPrefix:    "/", // should not change anything
+			},
+			{
+				name:         "some prefix",
+				path:         "/test",
+				expectedPath: "/foo/test",
+				upstreamURL:  "http://test.example.com",
+				addPrefix:    "/foo",
+			},
+		}
+
+		for _, tt := range tests {
+			t.Run(tt.name, func(t *testing.T) {
+				reqURL := types.MustParseURL("https://my.app" + tt.path)
+				upstreamURL := types.MustParseURL(tt.upstreamURL)
+
+				opts["add_prefix"] = tt.addPrefix
+				result, err := newMiddlewareTest(ModifyRequest, &testArgs{
+					middlewareOpt: opts,
+					reqURL:        reqURL,
+					upstreamURL:   upstreamURL,
+				})
+				ExpectNoError(t, err)
+				ExpectEqual(t, result.RequestHeaders.Get("X-Test-Req-Path"), tt.expectedPath)
+			})
+		}
+	})
+}
--- a/internal/net/gphttp/middleware/modify_response.go
+++ b/internal/net/gphttp/middleware/modify_response.go
@@ -0,0 +1,20 @@
+package middleware
+
+import (
+	"net/http"
+)
+
+type modifyResponse struct {
+	ModifyRequestOpts
+	Tracer
+}
+
+var ModifyResponse = NewMiddleware[modifyResponse]()
+
+// modifyResponse implements ResponseModifier.
+func (mr *modifyResponse) modifyResponse(resp *http.Response) error {
+	mr.AddTraceResponse("before modify response", resp)
+	mr.modifyHeaders(resp.Request, resp, resp.Header)
+	mr.AddTraceResponse("after modify response", resp)
+	return nil
+}
--- a/internal/net/gphttp/middleware/modify_response_test.go
+++ b/internal/net/gphttp/middleware/modify_response_test.go
@@ -0,0 +1,108 @@
+package middleware
+
+import (
+	"bytes"
+	"net"
+	"net/http"
+	"slices"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/net/types"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestModifyResponse(t *testing.T) {
+	opts := OptionsRaw{
+		"set_headers": map[string]string{
+			"X-Test-Resp-Status":              VarRespStatusCode,
+			"X-Test-Resp-Content-Type":        VarRespContentType,
+			"X-Test-Resp-Content-Length":      VarRespContentLen,
+			"X-Test-Resp-Header-Content-Type": "$resp_header(Content-Type)",
+
+			"X-Test-Req-Method":          VarRequestMethod,
+			"X-Test-Req-Scheme":          VarRequestScheme,
+			"X-Test-Req-Host":            VarRequestHost,
+			"X-Test-Req-Port":            VarRequestPort,
+			"X-Test-Req-Addr":            VarRequestAddr,
+			"X-Test-Req-Path":            VarRequestPath,
+			"X-Test-Req-Query":           VarRequestQuery,
+			"X-Test-Req-Url":             VarRequestURL,
+			"X-Test-Req-Uri":             VarRequestURI,
+			"X-Test-Req-Content-Type":    VarRequestContentType,
+			"X-Test-Req-Content-Length":  VarRequestContentLen,
+			"X-Test-Remote-Host":         VarRemoteHost,
+			"X-Test-Remote-Port":         VarRemotePort,
+			"X-Test-Remote-Addr":         VarRemoteAddr,
+			"X-Test-Upstream-Scheme":     VarUpstreamScheme,
+			"X-Test-Upstream-Host":       VarUpstreamHost,
+			"X-Test-Upstream-Port":       VarUpstreamPort,
+			"X-Test-Upstream-Addr":       VarUpstreamAddr,
+			"X-Test-Upstream-Url":        VarUpstreamURL,
+			"X-Test-Header-Content-Type": "$header(Content-Type)",
+			"X-Test-Arg-Arg_1":           "$arg(arg_1)",
+		},
+		"add_headers":  map[string]string{"Accept-Encoding": "test-value"},
+		"hide_headers": []string{"Accept"},
+	}
+
+	t.Run("set_options", func(t *testing.T) {
+		mr, err := ModifyResponse.New(opts)
+		ExpectNoError(t, err)
+		ExpectDeepEqual(t, mr.impl.(*modifyResponse).SetHeaders, opts["set_headers"].(map[string]string))
+		ExpectDeepEqual(t, mr.impl.(*modifyResponse).AddHeaders, opts["add_headers"].(map[string]string))
+		ExpectDeepEqual(t, mr.impl.(*modifyResponse).HideHeaders, opts["hide_headers"].([]string))
+	})
+
+	t.Run("response_headers", func(t *testing.T) {
+		reqURL := types.MustParseURL("https://my.app/?arg_1=b")
+		upstreamURL := types.MustParseURL("http://test.example.com")
+		result, err := newMiddlewareTest(ModifyResponse, &testArgs{
+			middlewareOpt: opts,
+			reqURL:        reqURL,
+			upstreamURL:   upstreamURL,
+			body:          bytes.Repeat([]byte("a"), 100),
+			headers: http.Header{
+				"Content-Type": []string{"application/json"},
+			},
+			respHeaders: http.Header{
+				"Content-Type": []string{"application/json"},
+			},
+			respBody:   bytes.Repeat([]byte("a"), 50),
+			respStatus: http.StatusOK,
+		})
+		ExpectNoError(t, err)
+		ExpectTrue(t, slices.Contains(result.ResponseHeaders.Values("Accept-Encoding"), "test-value"))
+		ExpectEqual(t, result.ResponseHeaders.Get("Accept"), "")
+
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Resp-Status"), "200")
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Resp-Content-Type"), "application/json")
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Resp-Content-Length"), "50")
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Resp-Header-Content-Type"), "application/json")
+
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Method"), http.MethodGet)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Scheme"), reqURL.Scheme)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Host"), reqURL.Hostname())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Port"), reqURL.Port())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Addr"), reqURL.Host)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Path"), reqURL.Path)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Query"), reqURL.RawQuery)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Url"), reqURL.String())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Uri"), reqURL.RequestURI())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Content-Type"), "application/json")
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Req-Content-Length"), "100")
+
+		remoteHost, remotePort, _ := net.SplitHostPort(result.RemoteAddr)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Remote-Host"), remoteHost)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Remote-Port"), remotePort)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Remote-Addr"), result.RemoteAddr)
+
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Upstream-Scheme"), upstreamURL.Scheme)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Upstream-Host"), upstreamURL.Hostname())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Upstream-Port"), upstreamURL.Port())
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Upstream-Addr"), upstreamURL.Host)
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Upstream-Url"), upstreamURL.String())
+
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Header-Content-Type"), "application/json")
+		ExpectEqual(t, result.ResponseHeaders.Get("X-Test-Arg-Arg_1"), "b")
+	})
+}
--- a/internal/net/gphttp/middleware/oidc.go
+++ b/internal/net/gphttp/middleware/oidc.go
@@ -0,0 +1,91 @@
+package middleware
+
+import (
+	"net/http"
+	"sync"
+	"sync/atomic"
+
+	"github.com/yusing/go-proxy/internal/api/v1/auth"
+	"github.com/yusing/go-proxy/internal/gperr"
+)
+
+type oidcMiddleware struct {
+	AllowedUsers  []string `json:"allowed_users"`
+	AllowedGroups []string `json:"allowed_groups"`
+
+	auth    auth.Provider
+	authMux *http.ServeMux
+
+	isInitialized int32
+	initMu        sync.Mutex
+}
+
+var OIDC = NewMiddleware[oidcMiddleware]()
+
+func (amw *oidcMiddleware) finalize() error {
+	if !auth.IsOIDCEnabled() {
+		return gperr.New("OIDC not enabled but OIDC middleware is used")
+	}
+	return nil
+}
+
+func (amw *oidcMiddleware) init() error {
+	if atomic.LoadInt32(&amw.isInitialized) == 1 {
+		return nil
+	}
+
+	return amw.initSlow()
+}
+
+func (amw *oidcMiddleware) initSlow() error {
+	amw.initMu.Lock()
+	if amw.isInitialized == 1 {
+		amw.initMu.Unlock()
+		return nil
+	}
+
+	defer func() {
+		amw.isInitialized = 1
+		amw.initMu.Unlock()
+	}()
+
+	authProvider, err := auth.NewOIDCProviderFromEnv()
+	if err != nil {
+		return err
+	}
+
+	authProvider.SetIsMiddleware(true)
+	if len(amw.AllowedUsers) > 0 {
+		authProvider.SetAllowedUsers(amw.AllowedUsers)
+	}
+	if len(amw.AllowedGroups) > 0 {
+		authProvider.SetAllowedGroups(amw.AllowedGroups)
+	}
+
+	amw.authMux = http.NewServeMux()
+	amw.authMux.HandleFunc(auth.OIDCMiddlewareCallbackPath, authProvider.LoginCallbackHandler)
+	amw.authMux.HandleFunc(auth.OIDCLogoutPath, func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+	})
+	amw.authMux.HandleFunc("/", authProvider.RedirectLoginPage)
+	amw.auth = authProvider
+	return nil
+}
+
+func (amw *oidcMiddleware) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	if err := amw.init(); err != nil {
+		// no need to log here, main OIDC may already failed and logged
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return false
+	}
+
+	if err := amw.auth.CheckToken(r); err != nil {
+		amw.authMux.ServeHTTP(w, r)
+		return false
+	}
+	if r.URL.Path == auth.OIDCLogoutPath {
+		amw.auth.LogoutCallbackHandler(w, r)
+		return false
+	}
+	return true
+}
--- a/internal/net/gphttp/middleware/rate_limit.go
+++ b/internal/net/gphttp/middleware/rate_limit.go
@@ -0,0 +1,73 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+	"sync"
+	"time"
+
+	"golang.org/x/time/rate"
+)
+
+type (
+	requestMap  = map[string]*rate.Limiter
+	rateLimiter struct {
+		RateLimiterOpts
+		Tracer
+
+		requestMap requestMap
+		mu         sync.Mutex
+	}
+
+	RateLimiterOpts struct {
+		Average int           `validate:"min=1,required"`
+		Burst   int           `validate:"min=1,required"`
+		Period  time.Duration `validate:"min=1s"`
+	}
+)
+
+var (
+	RateLimiter            = NewMiddleware[rateLimiter]()
+	rateLimiterOptsDefault = RateLimiterOpts{
+		Period: time.Second,
+	}
+)
+
+// setup implements MiddlewareWithSetup.
+func (rl *rateLimiter) setup() {
+	rl.RateLimiterOpts = rateLimiterOptsDefault
+	rl.requestMap = make(requestMap, 0)
+}
+
+// before implements RequestModifier.
+func (rl *rateLimiter) before(w http.ResponseWriter, r *http.Request) bool {
+	return rl.limit(w, r)
+}
+
+func (rl *rateLimiter) newLimiter() *rate.Limiter {
+	return rate.NewLimiter(rate.Limit(rl.Average)*rate.Every(rl.Period), rl.Burst)
+}
+
+func (rl *rateLimiter) limit(w http.ResponseWriter, r *http.Request) bool {
+	host, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		rl.AddTracef("unable to parse remote address %s", r.RemoteAddr)
+		http.Error(w, "Internal error", http.StatusInternalServerError)
+		return false
+	}
+
+	rl.mu.Lock()
+	limiter, ok := rl.requestMap[host]
+	if !ok {
+		limiter = rl.newLimiter()
+		rl.requestMap[host] = limiter
+	}
+	rl.mu.Unlock()
+
+	if limiter.Allow() {
+		return true
+	}
+
+	http.Error(w, "rate limit exceeded", http.StatusTooManyRequests)
+	return false
+}
--- a/internal/net/gphttp/middleware/rate_limit_test.go
+++ b/internal/net/gphttp/middleware/rate_limit_test.go
@@ -0,0 +1,27 @@
+package middleware
+
+import (
+	"net/http"
+	"testing"
+
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestRateLimit(t *testing.T) {
+	opts := OptionsRaw{
+		"average": "10",
+		"burst":   "10",
+		"period":  "1s",
+	}
+
+	rl, err := RateLimiter.New(opts)
+	ExpectNoError(t, err)
+	for range 10 {
+		result, err := newMiddlewareTest(rl, nil)
+		ExpectNoError(t, err)
+		ExpectEqual(t, result.ResponseStatus, http.StatusOK)
+	}
+	result, err := newMiddlewareTest(rl, nil)
+	ExpectNoError(t, err)
+	ExpectEqual(t, result.ResponseStatus, http.StatusTooManyRequests)
+}
--- a/internal/net/gphttp/middleware/real_ip.go
+++ b/internal/net/gphttp/middleware/real_ip.go
@@ -0,0 +1,116 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/types"
+)
+
+// https://nginx.org/en/docs/http/ngx_http_realip_module.html
+
+type (
+	realIP struct {
+		RealIPOpts
+		Tracer
+	}
+	RealIPOpts struct {
+		// Header is the name of the header to use for the real client IP
+		Header string `validate:"required"`
+		// From is a list of Address / CIDRs to trust
+		From []*types.CIDR `validate:"required,min=1"`
+		/*
+			If recursive search is disabled,
+			the original client address that matches one of the trusted addresses is replaced by
+			the last address sent in the request header field defined by the Header field.
+			If recursive search is enabled,
+			the original client address that matches one of the trusted addresses is replaced by
+			the last non-trusted address sent in the request header field.
+		*/
+		Recursive bool
+	}
+)
+
+var (
+	RealIP            = NewMiddleware[realIP]()
+	realIPOptsDefault = RealIPOpts{
+		Header: "X-Real-IP",
+		From:   []*types.CIDR{},
+	}
+)
+
+// setup implements MiddlewareWithSetup.
+func (ri *realIP) setup() {
+	ri.RealIPOpts = realIPOptsDefault
+}
+
+// before implements RequestModifier.
+func (ri *realIP) before(w http.ResponseWriter, r *http.Request) bool {
+	ri.setRealIP(r)
+	return true
+}
+
+func (ri *realIP) isInCIDRList(ip net.IP) bool {
+	for _, CIDR := range ri.From {
+		if CIDR.Contains(ip) {
+			return true
+		}
+	}
+	// not in any CIDR
+	return false
+}
+
+func (ri *realIP) setRealIP(req *http.Request) {
+	clientIPStr, _, err := net.SplitHostPort(req.RemoteAddr)
+	if err != nil {
+		clientIPStr = req.RemoteAddr
+	}
+
+	clientIP := net.ParseIP(clientIPStr)
+	isTrusted := false
+
+	for _, CIDR := range ri.From {
+		if CIDR.Contains(clientIP) {
+			isTrusted = true
+			break
+		}
+	}
+	if !isTrusted {
+		ri.AddTracef("client ip %s is not trusted", clientIP).With("allowed CIDRs", ri.From)
+		return
+	}
+
+	realIPs := req.Header.Values(ri.Header)
+	lastNonTrustedIP := ""
+
+	if len(realIPs) == 0 {
+		// try non-canonical key
+		realIPs = req.Header[ri.Header]
+	}
+
+	if len(realIPs) == 0 {
+		ri.AddTracef("no real ip found in header %s", ri.Header).WithRequest(req)
+		return
+	}
+
+	if !ri.Recursive {
+		lastNonTrustedIP = realIPs[len(realIPs)-1]
+	} else {
+		for _, r := range realIPs {
+			if !ri.isInCIDRList(net.ParseIP(r)) {
+				lastNonTrustedIP = r
+			}
+		}
+	}
+
+	if lastNonTrustedIP == "" {
+		ri.AddTracef("no non-trusted ip found").With("allowed CIDRs", ri.From).With("ips", realIPs)
+		return
+	}
+
+	req.RemoteAddr = lastNonTrustedIP
+	req.Header.Set(ri.Header, lastNonTrustedIP)
+	req.Header.Set(httpheaders.HeaderXRealIP, lastNonTrustedIP)
+	ri.AddTracef("set real ip %s", lastNonTrustedIP)
+}
--- a/internal/net/gphttp/middleware/real_ip_test.go
+++ b/internal/net/gphttp/middleware/real_ip_test.go
@@ -0,0 +1,77 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/types"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestSetRealIPOpts(t *testing.T) {
+	opts := OptionsRaw{
+		"header": httpheaders.HeaderXRealIP,
+		"from": []string{
+			"127.0.0.0/8",
+			"192.168.0.0/16",
+			"172.16.0.0/12",
+		},
+		"recursive": true,
+	}
+	optExpected := &RealIPOpts{
+		Header: httpheaders.HeaderXRealIP,
+		From: []*types.CIDR{
+			{
+				IP:   net.ParseIP("127.0.0.0"),
+				Mask: net.IPv4Mask(255, 0, 0, 0),
+			},
+			{
+				IP:   net.ParseIP("192.168.0.0"),
+				Mask: net.IPv4Mask(255, 255, 0, 0),
+			},
+			{
+				IP:   net.ParseIP("172.16.0.0"),
+				Mask: net.IPv4Mask(255, 240, 0, 0),
+			},
+		},
+		Recursive: true,
+	}
+
+	ri, err := RealIP.New(opts)
+	ExpectNoError(t, err)
+	ExpectEqual(t, ri.impl.(*realIP).Header, optExpected.Header)
+	ExpectEqual(t, ri.impl.(*realIP).Recursive, optExpected.Recursive)
+	for i, CIDR := range ri.impl.(*realIP).From {
+		ExpectEqual(t, CIDR.String(), optExpected.From[i].String())
+	}
+}
+
+func TestSetRealIP(t *testing.T) {
+	const (
+		testHeader = httpheaders.HeaderXRealIP
+		testRealIP = "192.168.1.1"
+	)
+	opts := OptionsRaw{
+		"header": testHeader,
+		"from":   []string{"0.0.0.0/0"},
+	}
+	optsMr := OptionsRaw{
+		"set_headers": map[string]string{testHeader: testRealIP},
+	}
+	realip, err := RealIP.New(opts)
+	ExpectNoError(t, err)
+
+	mr, err := ModifyRequest.New(optsMr)
+	ExpectNoError(t, err)
+
+	mid := NewMiddlewareChain("test", []*Middleware{mr, realip})
+
+	result, err := newMiddlewareTest(mid, nil)
+	ExpectNoError(t, err)
+	t.Log(traces)
+	ExpectEqual(t, result.ResponseStatus, http.StatusOK)
+	ExpectEqual(t, strings.Split(result.RemoteAddr, ":")[0], testRealIP)
+}
--- a/internal/net/gphttp/middleware/redirect_http.go
+++ b/internal/net/gphttp/middleware/redirect_http.go
@@ -0,0 +1,29 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/logging"
+)
+
+type redirectHTTP struct{}
+
+var RedirectHTTP = NewMiddleware[redirectHTTP]()
+
+// before implements RequestModifier.
+func (redirectHTTP) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	if r.TLS != nil {
+		return true
+	}
+	r.URL.Scheme = "https"
+	host := r.Host
+	if i := strings.Index(host, ":"); i != -1 {
+		host = host[:i] // strip port number if present
+	}
+	r.URL.Host = host + ":" + common.ProxyHTTPSPort
+	logging.Debug().Str("url", r.URL.String()).Msg("redirect to https")
+	http.Redirect(w, r, r.URL.String(), http.StatusTemporaryRedirect)
+	return true
+}
--- a/internal/net/gphttp/middleware/redirect_http_test.go
+++ b/internal/net/gphttp/middleware/redirect_http_test.go
@@ -0,0 +1,27 @@
+package middleware
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/net/types"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+func TestRedirectToHTTPs(t *testing.T) {
+	result, err := newMiddlewareTest(RedirectHTTP, &testArgs{
+		reqURL: types.MustParseURL("http://example.com"),
+	})
+	ExpectNoError(t, err)
+	ExpectEqual(t, result.ResponseStatus, http.StatusTemporaryRedirect)
+	ExpectEqual(t, result.ResponseHeaders.Get("Location"), "https://example.com:"+common.ProxyHTTPSPort)
+}
+
+func TestNoRedirect(t *testing.T) {
+	result, err := newMiddlewareTest(RedirectHTTP, &testArgs{
+		reqURL: types.MustParseURL("https://example.com"),
+	})
+	ExpectNoError(t, err)
+	ExpectEqual(t, result.ResponseStatus, http.StatusOK)
+}
--- a/internal/net/gphttp/middleware/set_upstream_headers.go
+++ b/internal/net/gphttp/middleware/set_upstream_headers.go
@@ -0,0 +1,37 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+	"github.com/yusing/go-proxy/internal/net/gphttp/reverseproxy"
+)
+
+// internal use only.
+type setUpstreamHeaders struct {
+	Name, Scheme, Host, Port string
+}
+
+var suh = NewMiddleware[setUpstreamHeaders]()
+
+func newSetUpstreamHeaders(rp *reverseproxy.ReverseProxy) *Middleware {
+	m, err := suh.New(OptionsRaw{
+		"name":   rp.TargetName,
+		"scheme": rp.TargetURL.Scheme,
+		"host":   rp.TargetURL.Hostname(),
+		"port":   rp.TargetURL.Port(),
+	})
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
+// before implements RequestModifier.
+func (s setUpstreamHeaders) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	r.Header.Set(httpheaders.HeaderUpstreamName, s.Name)
+	r.Header.Set(httpheaders.HeaderUpstreamScheme, s.Scheme)
+	r.Header.Set(httpheaders.HeaderUpstreamHost, s.Host)
+	r.Header.Set(httpheaders.HeaderUpstreamPort, s.Port)
+	return true
+}
--- a/internal/net/gphttp/middleware/test_data/cidr_whitelist_test.yml
+++ b/internal/net/gphttp/middleware/test_data/cidr_whitelist_test.yml
@@ -0,0 +1,23 @@
+deny:
+  - use: ModifyRequest
+    setHeaders:
+      X-Real-IP: 192.168.1.1:1234
+  - use: RealIP
+    header: X-Real-IP
+    from:
+      - 0.0.0.0/0
+  - use: CIDRWhitelist
+    allow:
+      - 192.168.0.0/24
+accept:
+  - use: ModifyRequest
+    setHeaders:
+      X-Real-IP: 192.168.0.1:1234
+  - use: RealIP
+    header: X-Real-IP
+    from:
+      - 0.0.0.0/0
+  - use: CIDRWhitelist
+    allow:
+      - 192.168.0.0/24
+      - 127.0.0.1
--- a/internal/net/gphttp/middleware/test_data/middleware_compose.yml
+++ b/internal/net/gphttp/middleware/test_data/middleware_compose.yml
@@ -0,0 +1,41 @@
+theGreatPretender:
+  - use: HideXForwarded
+  - use: ModifyRequest
+    setHeaders:
+      X-Real-IP: 6.6.6.6
+  - use: ModifyResponse
+    hideHeaders:
+      - X-Test3
+      - X-Test4
+
+notAuthenticAuthentik:
+  - use: RedirectHTTP
+  - use: ForwardAuth
+    address: https://authentik.company
+    trustForwardHeader: true
+    addAuthCookiesToResponse:
+      - session_id
+      - user_id
+    authResponseHeaders:
+      - X-Auth-SessionID
+      - X-Auth-UserID
+  - use: CustomErrorPage
+
+realIPAuthentik:
+  - use: RedirectHTTP
+  - use: RealIP
+    header: X-Real-IP
+    from:
+      - "127.0.0.0/8"
+      - "192.168.0.0/16"
+      - "172.16.0.0/12"
+    recursive: true
+  - use: ForwardAuth
+    address: https://authentik.company
+    trustForwardHeader: true
+
+testFakeRealIP:
+  - use: ModifyRequest
+    setHeaders:
+      CF-Connecting-IP: 127.0.0.1
+  - use: CloudflareRealIP
--- a/internal/net/gphttp/middleware/test_data/sample_headers.json
+++ b/internal/net/gphttp/middleware/test_data/sample_headers.json
@@ -0,0 +1,17 @@
+{
+    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7",
+    "Accept-Encoding": "gzip, deflate, br, zstd",
+    "Accept-Language": "en,zh-HK;q=0.9,zh-TW;q=0.8,zh-CN;q=0.7,zh;q=0.6",
+    "Dnt": "1",
+    "Host": "localhost",
+    "Priority": "u=0, i",
+    "Sec-Ch-Ua": "\"Chromium\";v=\"129\", \"Not=A?Brand\";v=\"8\"",
+    "Sec-Ch-Ua-Mobile": "?0",
+    "Sec-Ch-Ua-Platform": "\"Windows\"",
+    "Sec-Fetch-Dest": "document",
+    "Sec-Fetch-Mode": "navigate",
+    "Sec-Fetch-Site": "none",
+    "Sec-Fetch-User": "?1",
+    "Upgrade-Insecure-Requests": "1",
+    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36"
+}
--- a/internal/net/gphttp/middleware/test_utils.go
+++ b/internal/net/gphttp/middleware/test_utils.go
@@ -0,0 +1,176 @@
+package middleware
+
+import (
+	"bytes"
+	_ "embed"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/gperr"
+	"github.com/yusing/go-proxy/internal/net/gphttp/reverseproxy"
+	"github.com/yusing/go-proxy/internal/net/types"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
+)
+
+//go:embed test_data/sample_headers.json
+var testHeadersRaw []byte
+var testHeaders http.Header
+
+func init() {
+	if !common.IsTest {
+		return
+	}
+	tmp := map[string]string{}
+	err := json.Unmarshal(testHeadersRaw, &tmp)
+	if err != nil {
+		panic(err)
+	}
+	testHeaders = http.Header{}
+	for k, v := range tmp {
+		testHeaders.Set(k, v)
+	}
+}
+
+type requestRecorder struct {
+	args *testArgs
+
+	parent     http.RoundTripper
+	headers    http.Header
+	remoteAddr string
+}
+
+func newRequestRecorder(args *testArgs) *requestRecorder {
+	return &requestRecorder{args: args}
+}
+
+func (rt *requestRecorder) RoundTrip(req *http.Request) (resp *http.Response, err error) {
+	rt.headers = req.Header
+	rt.remoteAddr = req.RemoteAddr
+	if rt.parent != nil {
+		resp, err = rt.parent.RoundTrip(req)
+	} else {
+		resp = &http.Response{
+			Status:        http.StatusText(rt.args.respStatus),
+			StatusCode:    rt.args.respStatus,
+			Header:        testHeaders,
+			Body:          io.NopCloser(bytes.NewReader(rt.args.respBody)),
+			ContentLength: int64(len(rt.args.respBody)),
+			Request:       req,
+			TLS:           req.TLS,
+		}
+	}
+	if err == nil {
+		for k, v := range rt.args.respHeaders {
+			resp.Header[k] = v
+		}
+	}
+	return resp, nil
+}
+
+type TestResult struct {
+	RequestHeaders  http.Header
+	ResponseHeaders http.Header
+	ResponseStatus  int
+	RemoteAddr      string
+	Data            []byte
+}
+
+type testArgs struct {
+	middlewareOpt OptionsRaw
+	upstreamURL   *types.URL
+
+	realRoundTrip bool
+
+	reqURL    *types.URL
+	reqMethod string
+	headers   http.Header
+	body      []byte
+
+	respHeaders http.Header
+	respBody    []byte
+	respStatus  int
+}
+
+func (args *testArgs) setDefaults() {
+	if args.reqURL == nil {
+		args.reqURL = Must(types.ParseURL("https://example.com"))
+	}
+	if args.reqMethod == "" {
+		args.reqMethod = http.MethodGet
+	}
+	if args.upstreamURL == nil {
+		args.upstreamURL = Must(types.ParseURL("https://10.0.0.1:8443")) // dummy url, no actual effect
+	}
+	if args.respHeaders == nil {
+		args.respHeaders = http.Header{}
+	}
+	if args.respBody == nil {
+		args.respBody = []byte("OK")
+	}
+	if args.respStatus == 0 {
+		args.respStatus = http.StatusOK
+	}
+}
+
+func (args *testArgs) bodyReader() io.Reader {
+	if args.body != nil {
+		return bytes.NewReader(args.body)
+	}
+	return nil
+}
+
+func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, gperr.Error) {
+	if args == nil {
+		args = new(testArgs)
+	}
+	args.setDefaults()
+
+	mid, setOptErr := middleware.New(args.middlewareOpt)
+	if setOptErr != nil {
+		return nil, setOptErr
+	}
+
+	return newMiddlewaresTest([]*Middleware{mid}, args)
+}
+
+func newMiddlewaresTest(middlewares []*Middleware, args *testArgs) (*TestResult, gperr.Error) {
+	if args == nil {
+		args = new(testArgs)
+	}
+	args.setDefaults()
+
+	req := httptest.NewRequest(args.reqMethod, args.reqURL.String(), args.bodyReader())
+	for k, v := range args.headers {
+		req.Header[k] = v
+	}
+
+	w := httptest.NewRecorder()
+
+	rr := newRequestRecorder(args)
+	if args.realRoundTrip {
+		rr.parent = http.DefaultTransport
+	}
+
+	rp := reverseproxy.NewReverseProxy("test", args.upstreamURL, rr)
+	patchReverseProxy(rp, middlewares)
+	rp.ServeHTTP(w, req)
+
+	resp := w.Result()
+	defer resp.Body.Close()
+
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, gperr.Wrap(err)
+	}
+
+	return &TestResult{
+		RequestHeaders:  rr.headers,
+		ResponseHeaders: resp.Header,
+		ResponseStatus:  resp.StatusCode,
+		RemoteAddr:      rr.remoteAddr,
+		Data:            data,
+	}, nil
+}
--- a/internal/net/gphttp/middleware/trace.go
+++ b/internal/net/gphttp/middleware/trace.go
@@ -0,0 +1,87 @@
+package middleware
+
+import (
+	"net/http"
+	"sync"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+)
+
+type (
+	Trace struct {
+		Time        string            `json:"time,omitempty"`
+		Caller      string            `json:"caller,omitempty"`
+		URL         string            `json:"url,omitempty"`
+		Message     string            `json:"msg"`
+		ReqHeaders  map[string]string `json:"req_headers,omitempty"`
+		RespHeaders map[string]string `json:"resp_headers,omitempty"`
+		RespStatus  int               `json:"resp_status,omitempty"`
+		Additional  map[string]any    `json:"additional,omitempty"`
+	}
+	Traces []*Trace
+)
+
+var (
+	traces   = make(Traces, 0)
+	tracesMu sync.Mutex
+)
+
+const MaxTraceNum = 100
+
+func GetAllTrace() []*Trace {
+	return traces
+}
+
+func (tr *Trace) WithRequest(req *http.Request) *Trace {
+	if tr == nil {
+		return nil
+	}
+	tr.URL = req.RequestURI
+	tr.ReqHeaders = httpheaders.HeaderToMap(req.Header)
+	return tr
+}
+
+func (tr *Trace) WithResponse(resp *http.Response) *Trace {
+	if tr == nil {
+		return nil
+	}
+	tr.URL = resp.Request.RequestURI
+	tr.ReqHeaders = httpheaders.HeaderToMap(resp.Request.Header)
+	tr.RespHeaders = httpheaders.HeaderToMap(resp.Header)
+	tr.RespStatus = resp.StatusCode
+	return tr
+}
+
+func (tr *Trace) With(what string, additional any) *Trace {
+	if tr == nil {
+		return nil
+	}
+
+	if tr.Additional == nil {
+		tr.Additional = map[string]any{}
+	}
+	tr.Additional[what] = additional
+	return tr
+}
+
+func (tr *Trace) WithError(err error) *Trace {
+	if tr == nil {
+		return nil
+	}
+
+	if tr.Additional == nil {
+		tr.Additional = map[string]any{}
+	}
+	tr.Additional["error"] = err.Error()
+	return tr
+}
+
+func addTrace(t *Trace) *Trace {
+	tracesMu.Lock()
+	defer tracesMu.Unlock()
+	if len(traces) > MaxTraceNum {
+		traces = traces[1:]
+	}
+	traces = append(traces, t)
+	return t
+}
--- a/internal/net/gphttp/middleware/tracer.go
+++ b/internal/net/gphttp/middleware/tracer.go
@@ -0,0 +1,62 @@
+package middleware
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/yusing/go-proxy/internal/utils/strutils"
+)
+
+type Tracer struct {
+	name    string
+	enabled bool
+}
+
+func _() {
+	var _ MiddlewareWithTracer = &Tracer{}
+}
+
+func (t *Tracer) enableTrace() {
+	t.enabled = true
+}
+
+func (t *Tracer) getTracer() *Tracer {
+	return t
+}
+
+func (t *Tracer) SetParent(parent *Tracer) {
+	if parent == nil {
+		return
+	}
+	t.name = parent.name + "." + t.name
+}
+
+func (t *Tracer) addTrace(msg string) *Trace {
+	return addTrace(&Trace{
+		Time:    strutils.FormatTime(time.Now()),
+		Caller:  t.name,
+		Message: msg,
+	})
+}
+
+func (t *Tracer) AddTracef(msg string, args ...any) *Trace {
+	if !t.enabled {
+		return nil
+	}
+	return t.addTrace(fmt.Sprintf(msg, args...))
+}
+
+func (t *Tracer) AddTraceRequest(msg string, req *http.Request) *Trace {
+	if !t.enabled {
+		return nil
+	}
+	return t.addTrace(msg).WithRequest(req)
+}
+
+func (t *Tracer) AddTraceResponse(msg string, resp *http.Response) *Trace {
+	if !t.enabled {
+		return nil
+	}
+	return t.addTrace(msg).WithResponse(resp)
+}
--- a/internal/net/gphttp/middleware/vars.go
+++ b/internal/net/gphttp/middleware/vars.go
@@ -0,0 +1,175 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+)
+
+type (
+	reqVarGetter  func(*http.Request) string
+	respVarGetter func(*http.Response) string
+)
+
+var (
+	reArg        = regexp.MustCompile(`\$arg\([\w-_]+\)`)
+	reReqHeader  = regexp.MustCompile(`\$header\([\w-]+\)`)
+	reRespHeader = regexp.MustCompile(`\$resp_header\([\w-]+\)`)
+	reStatic     = regexp.MustCompile(`\$[\w_]+`)
+)
+
+const (
+	VarRequestMethod      = "$req_method"
+	VarRequestScheme      = "$req_scheme"
+	VarRequestHost        = "$req_host"
+	VarRequestPort        = "$req_port"
+	VarRequestPath        = "$req_path"
+	VarRequestAddr        = "$req_addr"
+	VarRequestQuery       = "$req_query"
+	VarRequestURL         = "$req_url"
+	VarRequestURI         = "$req_uri"
+	VarRequestContentType = "$req_content_type"
+	VarRequestContentLen  = "$req_content_length"
+	VarRemoteHost         = "$remote_host"
+	VarRemotePort         = "$remote_port"
+	VarRemoteAddr         = "$remote_addr"
+
+	VarUpstreamName   = "$upstream_name"
+	VarUpstreamScheme = "$upstream_scheme"
+	VarUpstreamHost   = "$upstream_host"
+	VarUpstreamPort   = "$upstream_port"
+	VarUpstreamAddr   = "$upstream_addr"
+	VarUpstreamURL    = "$upstream_url"
+
+	VarRespContentType = "$resp_content_type"
+	VarRespContentLen  = "$resp_content_length"
+	VarRespStatusCode  = "$status_code"
+)
+
+var staticReqVarSubsMap = map[string]reqVarGetter{
+	VarRequestMethod: func(req *http.Request) string { return req.Method },
+	VarRequestScheme: func(req *http.Request) string {
+		if req.TLS != nil {
+			return "https"
+		}
+		return "http"
+	},
+	VarRequestHost: func(req *http.Request) string {
+		reqHost, _, err := net.SplitHostPort(req.Host)
+		if err != nil {
+			return req.Host
+		}
+		return reqHost
+	},
+	VarRequestPort: func(req *http.Request) string {
+		_, reqPort, _ := net.SplitHostPort(req.Host)
+		return reqPort
+	},
+	VarRequestAddr:        func(req *http.Request) string { return req.Host },
+	VarRequestPath:        func(req *http.Request) string { return req.URL.Path },
+	VarRequestQuery:       func(req *http.Request) string { return req.URL.RawQuery },
+	VarRequestURL:         func(req *http.Request) string { return req.URL.String() },
+	VarRequestURI:         func(req *http.Request) string { return req.URL.RequestURI() },
+	VarRequestContentType: func(req *http.Request) string { return req.Header.Get("Content-Type") },
+	VarRequestContentLen:  func(req *http.Request) string { return strconv.FormatInt(req.ContentLength, 10) },
+	VarRemoteHost: func(req *http.Request) string {
+		clientIP, _, err := net.SplitHostPort(req.RemoteAddr)
+		if err == nil {
+			return clientIP
+		}
+		return ""
+	},
+	VarRemotePort: func(req *http.Request) string {
+		_, clientPort, err := net.SplitHostPort(req.RemoteAddr)
+		if err == nil {
+			return clientPort
+		}
+		return ""
+	},
+	VarRemoteAddr:     func(req *http.Request) string { return req.RemoteAddr },
+	VarUpstreamName:   func(req *http.Request) string { return req.Header.Get(httpheaders.HeaderUpstreamName) },
+	VarUpstreamScheme: func(req *http.Request) string { return req.Header.Get(httpheaders.HeaderUpstreamScheme) },
+	VarUpstreamHost:   func(req *http.Request) string { return req.Header.Get(httpheaders.HeaderUpstreamHost) },
+	VarUpstreamPort:   func(req *http.Request) string { return req.Header.Get(httpheaders.HeaderUpstreamPort) },
+	VarUpstreamAddr: func(req *http.Request) string {
+		upHost := req.Header.Get(httpheaders.HeaderUpstreamHost)
+		upPort := req.Header.Get(httpheaders.HeaderUpstreamPort)
+		if upPort != "" {
+			return upHost + ":" + upPort
+		}
+		return upHost
+	},
+	VarUpstreamURL: func(req *http.Request) string {
+		upScheme := req.Header.Get(httpheaders.HeaderUpstreamScheme)
+		if upScheme == "" {
+			return ""
+		}
+		upHost := req.Header.Get(httpheaders.HeaderUpstreamHost)
+		upPort := req.Header.Get(httpheaders.HeaderUpstreamPort)
+		upAddr := upHost
+		if upPort != "" {
+			upAddr += ":" + upPort
+		}
+		return upScheme + "://" + upAddr
+	},
+}
+
+var staticRespVarSubsMap = map[string]respVarGetter{
+	VarRespContentType: func(resp *http.Response) string { return resp.Header.Get("Content-Type") },
+	VarRespContentLen:  func(resp *http.Response) string { return strconv.FormatInt(resp.ContentLength, 10) },
+	VarRespStatusCode:  func(resp *http.Response) string { return strconv.Itoa(resp.StatusCode) },
+}
+
+func varReplace(req *http.Request, resp *http.Response, s string) string {
+	if req != nil {
+		// Replace query parameters
+		s = reArg.ReplaceAllStringFunc(s, func(match string) string {
+			name := match[5 : len(match)-1]
+			for k, v := range req.URL.Query() {
+				if strings.EqualFold(k, name) {
+					return v[0]
+				}
+			}
+			return ""
+		})
+
+		// Replace request headers
+		s = reReqHeader.ReplaceAllStringFunc(s, func(match string) string {
+			header := http.CanonicalHeaderKey(match[8 : len(match)-1])
+			return req.Header.Get(header)
+		})
+	}
+
+	if resp != nil {
+		// Replace response headers
+		s = reRespHeader.ReplaceAllStringFunc(s, func(match string) string {
+			header := http.CanonicalHeaderKey(match[13 : len(match)-1])
+			return resp.Header.Get(header)
+		})
+	}
+
+	// Replace static variables
+	if req != nil {
+		s = reStatic.ReplaceAllStringFunc(s, func(match string) string {
+			if fn, ok := staticReqVarSubsMap[match]; ok {
+				return fn(req)
+			}
+			return match
+		})
+	}
+
+	if resp != nil {
+		s = reStatic.ReplaceAllStringFunc(s, func(match string) string {
+			if fn, ok := staticRespVarSubsMap[match]; ok {
+				return fn(resp)
+			}
+			return match
+		})
+	}
+
+	return s
+}
--- a/internal/net/gphttp/middleware/x_forwarded.go
+++ b/internal/net/gphttp/middleware/x_forwarded.go
@@ -0,0 +1,45 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+	"strings"
+
+	"github.com/yusing/go-proxy/internal/net/gphttp/httpheaders"
+)
+
+type (
+	setXForwarded  struct{}
+	hideXForwarded struct{}
+)
+
+var (
+	SetXForwarded  = NewMiddleware[setXForwarded]()
+	HideXForwarded = NewMiddleware[hideXForwarded]()
+)
+
+// before implements RequestModifier.
+func (setXForwarded) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	r.Header.Del(httpheaders.HeaderXForwardedFor)
+	clientIP, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err == nil {
+		r.Header.Set(httpheaders.HeaderXForwardedFor, clientIP)
+	}
+	return true
+}
+
+// before implements RequestModifier.
+func (hideXForwarded) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
+	toDelete := make([]string, 0, len(r.Header))
+	for k := range r.Header {
+		if strings.HasPrefix(k, "X-Forwarded-") {
+			toDelete = append(toDelete, k)
+		}
+	}
+
+	for _, k := range toDelete {
+		r.Header.Del(k)
+	}
+
+	return true
+}