Merge pull request #87 from infinite-iroha/feat/headers-ops-v1

feat: 反向代理头部操作功能 (Headers Operations)

reverseproxy.go

@@ -20,6 +20,7 @@ import (
 	"net/netip"
 	"net/textproto"
 	"net/url"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -67,6 +68,9 @@ type ReverseProxyConfig struct {
 	ForwardedBy string
 	Via string
 	PreserveHost bool
+
+	RequestHeaders *HeaderOps
+	ResponseHeaders *RespHeaderOps
 }
 
 var (
@@ -76,6 +80,244 @@ var (
 	errReverseProxyNoAvailableUpstreams = errors.New("reverse proxy has no available upstreams")
 )
 
+type HeaderOps struct {
+	Add     map[string][]string
+	Set     map[string][]string
+	Delete  []string
+	Replace map[string][]Replacement
+}
+
+type Replacement struct {
+	Search       string
+	Replace      string
+	SearchRegexp string
+	re           *regexp.Regexp
+}
+
+type RespHeaderOps struct {
+	*HeaderOps
+	Deferred bool
+}
+
+func (ops *HeaderOps) applyToRequest(req *http.Request) {
+	if ops == nil {
+		return
+	}
+	ops.applyTo(req.Header, newReverseProxyReplacer(req))
+}
+
+func (ops *RespHeaderOps) applyToResponse(hdr http.Header) {
+	if ops == nil {
+		return
+	}
+	ops.applyTo(hdr, newReverseProxyReplacerFromHeader(hdr))
+}
+
+func (ops *HeaderOps) applyTo(hdr http.Header, repl *reverseProxyReplacer) {
+	if ops == nil {
+		return
+	}
+	if repl == nil {
+		repl = &reverseProxyReplacer{}
+	}
+	
+	for fieldName, vals := range ops.Add {
+		fieldName = repl.Replace(fieldName)
+		for _, v := range vals {
+			hdr.Add(fieldName, repl.Replace(v))
+		}
+	}
+	
+	for fieldName, vals := range ops.Set {
+		fieldName = repl.Replace(fieldName)
+		hdr.Del(fieldName)
+		for _, v := range vals {
+			hdr.Add(fieldName, repl.Replace(v))
+		}
+	}
+	
+	var deleteAll bool
+	var exactDeletes []string
+	var suffixPatterns, prefixPatterns, containsPatterns []string
+
+	for _, fieldName := range ops.Delete {
+		fieldName = strings.ToLower(repl.Replace(fieldName))
+		if fieldName == "*" {
+			deleteAll = true
+			break
+		}
+		switch {
+		case strings.HasPrefix(fieldName, "*") && strings.HasSuffix(fieldName, "*"):
+			containsPatterns = append(containsPatterns, fieldName[1:len(fieldName)-1])
+		case strings.HasPrefix(fieldName, "*"):
+			suffixPatterns = append(suffixPatterns, fieldName[1:])
+		case strings.HasSuffix(fieldName, "*"):
+			prefixPatterns = append(prefixPatterns, fieldName[:len(fieldName)-1])
+		default:
+			exactDeletes = append(exactDeletes, fieldName)
+		}
+	}
+
+	if deleteAll {
+		for k := range hdr {
+			hdr.Del(k)
+		}
+	} else if len(exactDeletes) > 0 || len(suffixPatterns) > 0 || len(prefixPatterns) > 0 || len(containsPatterns) > 0 {
+		toDelete := make([]string, 0, len(exactDeletes))
+		for k := range hdr {
+			kl := strings.ToLower(k)
+			for _, d := range exactDeletes {
+				if kl == d {
+					toDelete = append(toDelete, k)
+					goto skip
+				}
+			}
+			for _, p := range containsPatterns {
+				if strings.Contains(kl, p) {
+					toDelete = append(toDelete, k)
+					goto skip
+				}
+			}
+			for _, p := range suffixPatterns {
+				if strings.HasSuffix(kl, p) {
+					toDelete = append(toDelete, k)
+					goto skip
+				}
+			}
+			for _, p := range prefixPatterns {
+				if strings.HasPrefix(kl, p) {
+					toDelete = append(toDelete, k)
+					goto skip
+				}
+			}
+		skip:
+		}
+		for _, k := range toDelete {
+			hdr.Del(k)
+		}
+	}
+
+	ops.applyReplace(hdr, repl)
+}
+
+func (ops *HeaderOps) applyReplace(hdr http.Header, repl *reverseProxyReplacer) {
+	if ops == nil || len(ops.Replace) == 0 {
+		return
+	}
+	for fieldName, replacements := range ops.Replace {
+		fieldName = http.CanonicalHeaderKey(repl.Replace(fieldName))
+		if fieldName == "*" {
+			for fn, vals := range hdr {
+				for i := range vals {
+					for _, r := range replacements {
+						hdr[fn][i] = r.apply(vals[i])
+					}
+				}
+			}
+			continue
+		}
+		vals, ok := hdr[fieldName]
+		if !ok {
+			continue
+		}
+		for i := range vals {
+			for _, r := range replacements {
+				hdr[fieldName][i] = r.apply(vals[i])
+			}
+		}
+	}
+}
+
+func (r *Replacement) apply(s string) string {
+	if r == nil || s == "" {
+		return s
+	}
+	if r.SearchRegexp != "" && r.re != nil {
+		return r.re.ReplaceAllString(s, r.Replace)
+	}
+	if r.Search != "" {
+		return strings.ReplaceAll(s, r.Search, r.Replace)
+	}
+	return s
+}
+
+func (ops *HeaderOps) Provision() error {
+	if ops == nil {
+		return nil
+	}
+	for fieldName, replacements := range ops.Replace {
+		for i, r := range replacements {
+			if r.SearchRegexp == "" {
+				continue
+			}
+			if r.Search != "" {
+				return fmt.Errorf("replacement %d for header field %q: cannot specify both Search and SearchRegexp", i, fieldName)
+			}
+			re, err := regexp.Compile(r.SearchRegexp)
+			if err != nil {
+				return fmt.Errorf("replacement %d for header field %q: %v", i, fieldName, err)
+			}
+			replacements[i].re = re
+		}
+	}
+	return nil
+}
+
+type reverseProxyReplacer struct {
+	method, host, path, query, scheme, uri, proto string
+}
+
+func newReverseProxyReplacer(req *http.Request) *reverseProxyReplacer {
+	if req == nil || req.URL == nil {
+		return &reverseProxyReplacer{}
+	}
+	uri := req.RequestURI
+	if uri == "" {
+		uri = req.URL.RequestURI()
+	}
+	return &reverseProxyReplacer{
+		method: req.Method,
+		host:   req.Host,
+		path:   req.URL.EscapedPath(),
+		query:  req.URL.RawQuery,
+		scheme: reverseProxyRequestScheme(req),
+		uri:    uri,
+		proto:  req.Proto,
+	}
+}
+
+func newReverseProxyReplacerFromHeader(hdr http.Header) *reverseProxyReplacer {
+	return &reverseProxyReplacer{}
+}
+
+func (r *reverseProxyReplacer) Replace(s string) string {
+	if r == nil || s == "" {
+		return s
+	}
+	if r.method != "" {
+		s = strings.ReplaceAll(s, "{method}", r.method)
+	}
+	if r.host != "" {
+		s = strings.ReplaceAll(s, "{host}", r.host)
+	}
+	if r.path != "" {
+		s = strings.ReplaceAll(s, "{path}", r.path)
+	}
+	if r.query != "" {
+		s = strings.ReplaceAll(s, "{query}", r.query)
+	}
+	if r.scheme != "" {
+		s = strings.ReplaceAll(s, "{scheme}", r.scheme)
+	}
+	if r.uri != "" {
+		s = strings.ReplaceAll(s, "{uri}", r.uri)
+	}
+	if r.proto != "" {
+		s = strings.ReplaceAll(s, "{proto}", r.proto)
+	}
+	return s
+}
+
 type reverseProxyHandler struct {
 	config      ReverseProxyConfig
 	upstreams   []*reverseProxyUpstream
@@ -256,6 +498,19 @@ func newReverseProxyHandler(config ReverseProxyConfig) *reverseProxyHandler {
 		receivedBy: reverseProxyReceivedBy(config.Via),
 	}
 
+	if config.RequestHeaders != nil {
+		if err := config.RequestHeaders.Provision(); err != nil {
+			proxy.configError = err
+			return proxy
+		}
+	}
+	if config.ResponseHeaders != nil && config.ResponseHeaders.HeaderOps != nil {
+		if err := config.ResponseHeaders.HeaderOps.Provision(); err != nil {
+			proxy.configError = err
+			return proxy
+		}
+	}
+
 	upstreams, err := buildReverseProxyUpstreams(config)
 	if err != nil {
 		proxy.configError = err
@@ -573,6 +828,10 @@ func (p *reverseProxyHandler) buildOutgoingRequest(c *Context, ctx context.Conte
 		outreq.Header.Set("User-Agent", "")
 	}
 
+	if p.config.RequestHeaders != nil {
+		p.config.RequestHeaders.applyToRequest(outreq)
+	}
+
 	if p.config.ModifyRequest != nil {
 		p.config.ModifyRequest(outreq)
 	}
@@ -808,7 +1067,14 @@ func appendXForwardedFor(header http.Header, clientIP string) {
 }
 
 func (p *reverseProxyHandler) modifyResponse(c *Context, res *http.Response, req *http.Request) bool {
+	if p.config.ResponseHeaders != nil && !p.config.ResponseHeaders.Deferred {
+		p.config.ResponseHeaders.applyToResponse(res.Header)
+	}
+
 	if p.config.ModifyResponse == nil {
+		if p.config.ResponseHeaders != nil && p.config.ResponseHeaders.Deferred {
+			p.config.ResponseHeaders.applyToResponse(res.Header)
+		}
 		return true
 	}
 	if err := p.config.ModifyResponse(res); err != nil {
@@ -816,6 +1082,9 @@ func (p *reverseProxyHandler) modifyResponse(c *Context, res *http.Response, req
 		p.handleError(c, err)
 		return false
 	}
+	if p.config.ResponseHeaders != nil && p.config.ResponseHeaders.Deferred {
+		p.config.ResponseHeaders.applyToResponse(res.Header)
+	}
 	return true
 }
 

reverseproxy_headers_replace_test.go

@@ -0,0 +1,530 @@
+package touka
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"regexp"
+	"testing"
+)
+
+func TestReverseProxyHeaderOpsReplaceSubstring(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("X-Server"); got != "Caddy" {
+			t.Errorf("expected X-Server=Caddy, got %q", got)
+		}
+		if got := r.Header.Get("X-Location"); got != "/api/v2/resource" {
+			t.Errorf("expected X-Location=/api/v2/resource, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Replace: map[string][]Replacement{
+				"X-Server":   {{Search: "NGINX", Replace: "Caddy"}},
+				"X-Location": {{Search: "v1", Replace: "v2"}},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	req.Header.Set("X-Server", "NGINX")
+	req.Header.Set("X-Location", "/api/v1/resource")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyHeaderOpsReplaceRegexp(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("X-Route"); got != "/proxy-upstream" {
+			t.Errorf("expected X-Route=/proxy-upstream, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Replace: map[string][]Replacement{
+				"X-Route": {{SearchRegexp: `^/([^/]+)/(.+)$`, Replace: "/proxy-$2"}},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	req.Header.Set("X-Route", "/original/upstream")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyHeaderOpsReplaceWildcard(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("X-Host-A"); got != "new.example.com" {
+			t.Errorf("expected X-Host-A=new.example.com, got %q", got)
+		}
+		if got := r.Header.Get("X-Host-B"); got != "new.example.com" {
+			t.Errorf("expected X-Host-B=new.example.com, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Replace: map[string][]Replacement{
+				"*": {{Search: "old.example.com", Replace: "new.example.com"}},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	req.Header.Set("X-Host-A", "old.example.com")
+	req.Header.Set("X-Host-B", "old.example.com")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyHeaderOpsReplaceResponse(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Backend", "backend-internal:8080")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		ResponseHeaders: &RespHeaderOps{
+			HeaderOps: &HeaderOps{
+				Replace: map[string][]Replacement{
+					"X-Backend": {{Search: "backend-internal:8080", Replace: "public.example.com"}},
+				},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	resp, err := http.Get(proxy.URL + "/test")
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if got := resp.Header.Get("X-Backend"); got != "public.example.com" {
+		t.Errorf("expected X-Backend=public.example.com, got %q", got)
+	}
+}
+
+func TestReverseProxyHeaderOpsProvisionInvalidRegexp(t *testing.T) {
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Replace: map[string][]Replacement{
+				"X-Test": {{SearchRegexp: "[invalid"}},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusInternalServerError {
+		t.Errorf("expected status 500, got %d", resp.StatusCode)
+	}
+}
+
+func TestReplacementApply(t *testing.T) {
+	tests := []struct {
+		name string
+		r    *Replacement
+		s    string
+		want string
+	}{
+		{name: "nil replacement", r: nil, s: "hello", want: "hello"},
+		{name: "empty string", r: &Replacement{Search: "x", Replace: "y"}, s: "", want: ""},
+		{name: "substring match", r: &Replacement{Search: "world", Replace: "go"}, s: "hello world", want: "hello go"},
+		{name: "substring no match", r: &Replacement{Search: "foo", Replace: "bar"}, s: "hello world", want: "hello world"},
+		{name: "substring multiple", r: &Replacement{Search: "a", Replace: "b"}, s: "aaa", want: "bbb"},
+		{name: "regexp match", r: &Replacement{SearchRegexp: `\d+`, Replace: "N", re: regexp.MustCompile(`\d+`)}, s: "abc123def", want: "abcNdef"},
+		{name: "regexp no match", r: &Replacement{SearchRegexp: `z+`, Replace: "Z", re: regexp.MustCompile(`z+`)}, s: "abc", want: "abc"},
+		{name: "empty search and regexp", r: &Replacement{}, s: "unchanged", want: "unchanged"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.r.apply(tt.s); got != tt.want {
+				t.Errorf("Replacement.apply() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func BenchmarkHeaderOpsAdd(b *testing.B) {
+	ops := &HeaderOps{
+		Add: map[string][]string{
+			"X-Custom-1": {"value-1"},
+			"X-Custom-2": {"value-2"},
+			"X-Custom-3": {"value-3"},
+		},
+	}
+	hdr := make(http.Header)
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr = make(http.Header)
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsSet(b *testing.B) {
+	ops := &HeaderOps{
+		Set: map[string][]string{
+			"X-Frame-Options":    {"DENY"},
+			"X-Content-Type-Options": {"nosniff"},
+			"X-XSS-Protection":   {"1; mode=block"},
+		},
+	}
+	hdr := make(http.Header)
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr = make(http.Header)
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsDeleteSingle(b *testing.B) {
+	ops := &HeaderOps{
+		Delete: []string{"X-Powered-By"},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("X-Powered-By", "Express")
+		hdr.Set("X-Keep", "value")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsDeleteWildcard(b *testing.B) {
+	ops := &HeaderOps{
+		Delete: []string{"X-Debug-*"},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("X-Debug-1", "v1")
+		hdr.Set("X-Debug-2", "v2")
+		hdr.Set("X-Keep", "value")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsReplaceSubstring(b *testing.B) {
+	ops := &HeaderOps{
+		Replace: map[string][]Replacement{
+			"Location": {{Search: "http://internal:8080", Replace: "https://public.example.com"}},
+		},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("Location", "http://internal:8080/api/v1/users")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsReplaceRegexp(b *testing.B) {
+	re := regexp.MustCompile(`^http://([^/]+)(/.*)$`)
+	ops := &HeaderOps{
+		Replace: map[string][]Replacement{
+			"Location": {{SearchRegexp: `^http://([^/]+)(/.*)$`, Replace: "https://public.example.com$2", re: re}},
+		},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("Location", "http://internal:8080/api/v1/users")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsReplaceWildcard(b *testing.B) {
+	ops := &HeaderOps{
+		Replace: map[string][]Replacement{
+			"*": {{Search: "internal.example.com", Replace: "public.example.com"}},
+		},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("X-Host", "internal.example.com")
+		hdr.Set("X-Origin", "internal.example.com")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkHeaderOpsMixed(b *testing.B) {
+	ops := &HeaderOps{
+		Add: map[string][]string{
+			"X-Request-ID": {"req-123"},
+		},
+		Set: map[string][]string{
+			"X-Frame-Options": {"DENY"},
+		},
+		Delete: []string{"X-Powered-By"},
+		Replace: map[string][]Replacement{
+			"Location": {{Search: "http://internal:8080", Replace: "https://public.example.com"}},
+		},
+	}
+	repl := &reverseProxyReplacer{}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		hdr := make(http.Header)
+		hdr.Set("X-Powered-By", "Express")
+		hdr.Set("Location", "http://internal:8080/api")
+		ops.applyTo(hdr, repl)
+	}
+}
+
+func BenchmarkReplacementApplySubstring(b *testing.B) {
+	r := &Replacement{Search: "old.example.com", Replace: "new.example.com"}
+	s := "https://old.example.com/api/v1/resource"
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = r.apply(s)
+	}
+}
+
+func BenchmarkReplacementApplyRegexp(b *testing.B) {
+	r := &Replacement{SearchRegexp: `^https?://[^/]+`, Replace: "https://new.example.com", re: regexp.MustCompile(`^https?://[^/]+`)}
+	s := "https://old.example.com/api/v1/resource"
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = r.apply(s)
+	}
+}
+
+func TestReverseProxyReplacerDynamicVars(t *testing.T) {
+	req, _ := http.NewRequest(http.MethodGet, "http://example.com/api/v1/users?sort=name&limit=10", nil)
+	req.Host = "example.com"
+	repl := newReverseProxyReplacer(req)
+
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{"method", "{method}", "GET"},
+		{"host", "{host}", "example.com"},
+		{"path", "{path}", "/api/v1/users"},
+		{"query", "{query}", "sort=name&limit=10"},
+		{"scheme", "{scheme}", "http"},
+		{"proto", "{proto}", "HTTP/1.1"},
+		{"combined", "X-{method}-{path}", "X-GET-/api/v1/users"},
+		{"no vars", "static-value", "static-value"},
+		{"empty", "", ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := repl.Replace(tt.input); got != tt.want {
+				t.Errorf("Replace(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestReverseProxyReplacerNilRequest(t *testing.T) {
+	repl := newReverseProxyReplacer(nil)
+	if got := repl.Replace("{method}"); got != "{method}" {
+		t.Errorf("expected unchanged string with nil request, got %q", got)
+	}
+}
+
+func TestReverseProxyReplacerNilReplacer(t *testing.T) {
+	var repl *reverseProxyReplacer
+	if got := repl.Replace("{method}"); got != "{method}" {
+		t.Errorf("expected unchanged string with nil replacer, got %q", got)
+	}
+}
+
+func TestReverseProxyReplacerFromHeader(t *testing.T) {
+	hdr := make(http.Header)
+	repl := newReverseProxyReplacerFromHeader(hdr)
+	if got := repl.Replace("{method}"); got != "{method}" {
+		t.Errorf("expected unchanged string from header replacer, got %q", got)
+	}
+}
+
+func TestReverseProxyHeaderOpsWithDynamicVars(t *testing.T) {
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("X-Forwarded-Path"); got != "/dynamic/path" {
+			t.Errorf("expected X-Forwarded-Path=/dynamic/path, got %q", got)
+		}
+		if got := r.Header.Get("X-Forwarded-Method"); got != "GET" {
+			t.Errorf("expected X-Forwarded-Method=GET, got %q", got)
+		}
+		if got := r.Header.Get("X-Forwarded-Host"); got != "client.example" {
+			t.Errorf("expected X-Forwarded-Host=client.example, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/dynamic/path", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Add: map[string][]string{
+				"X-Forwarded-Path":   {"{path}"},
+				"X-Forwarded-Method": {"{method}"},
+				"X-Forwarded-Host":   {"{host}"},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/dynamic/path", nil)
+	req.Host = "client.example"
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}

reverseproxy_headers_test.go

@@ -0,0 +1,220 @@
+package touka
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+)
+
+func TestReverseProxyHeaderOpsAdd(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("X-Custom-Header"); got != "test-value" {
+			t.Errorf("expected X-Custom-Header=test-value, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Add: map[string][]string{
+				"X-Custom-Header": {"test-value"},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	resp, err := http.Get(proxy.URL + "/test")
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyHeaderOpsDelete(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("X-Sensitive") != "" {
+			t.Errorf("expected X-Sensitive header to be deleted, got %q", r.Header.Get("X-Sensitive"))
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Delete: []string{"X-Sensitive"},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	req.Header.Set("X-Sensitive", "should-be-removed")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyHeaderOpsSet(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		got := r.Header.Get("X-Replace")
+		if got != "new-value" {
+			t.Errorf("expected X-Replace=new-value, got %q", got)
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		RequestHeaders: &HeaderOps{
+			Set: map[string][]string{
+				"X-Replace": {"new-value"},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	req, _ := http.NewRequest(http.MethodGet, proxy.URL+"/test", nil)
+	req.Header.Set("X-Replace", "old-value")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestReverseProxyResponseHeaderOps(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Backend", "backend-server")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		ResponseHeaders: &RespHeaderOps{
+			HeaderOps: &HeaderOps{
+				Set: map[string][]string{
+					"X-Custom": {"custom-value"},
+				},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	resp, err := http.Get(proxy.URL + "/test")
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if got := resp.Header.Get("X-Custom"); got != "custom-value" {
+		t.Errorf("expected X-Custom=custom-value, got %q", got)
+	}
+}
+
+func TestReverseProxyResponseHeaderOpsDelete(t *testing.T) {
+	t.Helper()
+
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Powered-By", "Express")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	}))
+	defer backend.Close()
+
+	target, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse target: %v", err)
+	}
+
+	engine := New()
+	engine.GET("/test", ReverseProxy(ReverseProxyConfig{
+		Target: target,
+		ResponseHeaders: &RespHeaderOps{
+			HeaderOps: &HeaderOps{
+				Delete: []string{"X-Powered-By"},
+			},
+		},
+	}))
+
+	proxy := httptest.NewServer(engine)
+	defer proxy.Close()
+
+	resp, err := http.Get(proxy.URL + "/test")
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
+	defer resp.Body.Close()
+	_, _ = io.ReadAll(resp.Body)
+
+	if got := resp.Header.Get("X-Powered-By"); got != "" {
+		t.Errorf("expected X-Powered-By to be deleted, got %q", got)
+	}
+}