add http body rewrite for forward handler

config/config.go

@@ -376,6 +376,13 @@ type HTTPURLRewriteConfig struct {
 	Replacement string
 }
 
+type HTTPBodyRewriteConfig struct {
+	// filter by MIME types
+	Type        string
+	Match       string
+	Replacement string
+}
+
 type NodeFilterConfig struct {
 	Host     string `yaml:",omitempty" json:"host,omitempty"`
 	Protocol string `yaml:",omitempty" json:"protocol,omitempty"`
@@ -383,10 +390,16 @@ type NodeFilterConfig struct {
 }
 
 type HTTPNodeConfig struct {
-	Host    string                 `yaml:",omitempty" json:"host,omitempty"`
+	// rewrite host header
-	Header  map[string]string      `yaml:",omitempty" json:"header,omitempty"`
+	Host string `yaml:",omitempty" json:"host,omitempty"`
+	// additional request header
+	Header map[string]string `yaml:",omitempty" json:"header,omitempty"`
+	// rewrite URL
 	Rewrite []HTTPURLRewriteConfig `yaml:",omitempty" json:"rewrite,omitempty"`
-	Auth    *AuthConfig            `yaml:",omitempty" json:"auth,omitempty"`
+	// rewrite response body
+	RewriteBody []HTTPBodyRewriteConfig `yaml:"rewriteBody,omitempty" json:"rewriteBody,omitempty"`
+	// HTTP basic auth
+	Auth *AuthConfig `yaml:",omitempty" json:"auth,omitempty"`
 }
 
 type TLSNodeConfig struct {

config/parsing/node/parse.go

@@ -193,12 +193,21 @@ func ParseNode(hop string, cfg *config.NodeConfig, log logger.Logger) (*chain.No
 		}
 		for _, v := range cfg.HTTP.Rewrite {
 			if pattern, _ := regexp.Compile(v.Match); pattern != nil {
-				settings.Rewrite = append(settings.Rewrite, chain.HTTPURLRewriteSetting{
+				settings.RewriteURL = append(settings.RewriteURL, chain.HTTPURLRewriteSetting{
 					Pattern:     pattern,
 					Replacement: v.Replacement,
 				})
 			}
 		}
+		for _, v := range cfg.HTTP.RewriteBody {
+			if pattern, _ := regexp.Compile(v.Match); pattern != nil {
+				settings.RewriteBody = append(settings.RewriteBody, chain.HTTPBodyRewriteSettings{
+					Type:        v.Type,
+					Pattern:     pattern,
+					Replacement: []byte(v.Replacement),
+				})
+			}
+		}
 		opts = append(opts, chain.HTTPNodeOption(settings))
 	}
 

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/asaskevich/govalidator v0.0.0-20210307081110-f21760c49a8d
 	github.com/gin-contrib/cors v1.6.0
 	github.com/gin-gonic/gin v1.9.1
-	github.com/go-gost/core v0.1.0
+	github.com/go-gost/core v0.1.1
 	github.com/go-gost/gosocks4 v0.0.1
 	github.com/go-gost/gosocks5 v0.4.2
 	github.com/go-gost/plugin v0.0.0-20240103125338-9c84e29cb81a

go.sum

@@ -53,8 +53,8 @@ github.com/gin-contrib/sse v0.1.0 h1:Y/yl/+YNO8GZSjAhjMsSuLt29uWRFHdHYUb5lYOV9qE
 github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
 github.com/gin-gonic/gin v1.9.1 h1:4idEAncQnU5cB7BeOkPtxjfCSye0AAm1R0RVIqJ+Jmg=
 github.com/gin-gonic/gin v1.9.1/go.mod h1:hPrL7YrpYKXt5YId3A/Tnip5kqbEAP+KLuI3SUcPTeU=
-github.com/go-gost/core v0.1.0 h1:LJJc8PIlRflE8ZIpxls+wYX1e8OGB0nUKJYh8HevM4U=
+github.com/go-gost/core v0.1.1 h1:8joR9KJYBvpurNu3i0zqN9orQthVzOjhtT4STumwNF0=
-github.com/go-gost/core v0.1.0/go.mod h1:WGI43jOka7FAsSAwi/fSMaqxdR+E339ycb4NBGlFr6A=
+github.com/go-gost/core v0.1.1/go.mod h1:WGI43jOka7FAsSAwi/fSMaqxdR+E339ycb4NBGlFr6A=
 github.com/go-gost/gosocks4 v0.0.1 h1:+k1sec8HlELuQV7rWftIkmy8UijzUt2I6t+iMPlGB2s=
 github.com/go-gost/gosocks4 v0.0.1/go.mod h1:3B6L47HbU/qugDg4JnoFPHgJXE43Inz8Bah1QaN9qCc=
 github.com/go-gost/gosocks5 v0.4.2 h1:IianxHTkACPqCwiOAT3MHoMdSUl+SEPSRu1ikawC1Pc=

handler/forward/local/handler.go

@@ -2,6 +2,7 @@ package local
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"crypto/tls"
 	"errors"
@@ -179,8 +180,9 @@ func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...hand
 func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remoteAddr net.Addr, log logger.Logger) (err error) {
 	br := bufio.NewReader(rw)
 
-	var cc net.Conn
 	for {
+		var cc net.Conn
+
 		resp := &http.Response{
 			ProtoMajor: 1,
 			ProtoMinor: 1,
@@ -241,6 +243,7 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 			})
 			log.Debugf("find node for host %s -> %s(%s)", req.Host, target.Name, target.Addr)
 
+			var bodyRewrites []chain.HTTPBodyRewriteSettings
 			if httpSettings := target.Options().HTTP; httpSettings != nil {
 				if auther := httpSettings.Auther; auther != nil {
 					username, password, _ := req.BasicAuth()
@@ -261,7 +264,7 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 					req.Header.Set(k, v)
 				}
 
-				for _, re := range httpSettings.Rewrite {
+				for _, re := range httpSettings.RewriteURL {
 					if re.Pattern.MatchString(req.URL.Path) {
 						if s := re.Pattern.ReplaceAllString(req.URL.Path, re.Replacement); s != "" {
 							req.URL.Path = s
@@ -269,6 +272,8 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 						}
 					}
 				}
+
+				bodyRewrites = httpSettings.RewriteBody
 			}
 
 			cc, err = h.options.Router.Dial(ctx, "tcp", target.Addr)
@@ -329,6 +334,11 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 					log.Trace(string(dump))
 				}
 
+				if err := h.rewriteBody(res, bodyRewrites...); err != nil {
+					log.Errorf("rewrite body: %v", err)
+					return
+				}
+
 				if err = res.Write(rw); err != nil {
 					log.Errorf("write response from node %s(%s): %v", target.Name, target.Addr, err)
 				}
@@ -348,6 +358,54 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 	return
 }
 
+func (h *forwardHandler) rewriteBody(resp *http.Response, rewrites ...chain.HTTPBodyRewriteSettings) error {
+	if resp == nil || len(rewrites) == 0 || resp.ContentLength <= 0 {
+		return nil
+	}
+
+	if encoding := resp.Header.Get("Content-Encoding"); encoding != "" {
+		return nil
+	}
+
+	body, err := drainBody(resp.Body)
+	if err != nil || body == nil {
+		return err
+	}
+
+	contentType, _, _ := strings.Cut(resp.Header.Get("Content-Type"), ";")
+	for _, rewrite := range rewrites {
+		rewriteType := rewrite.Type
+		if rewriteType == "" {
+			rewriteType = "text/html"
+		}
+		if rewriteType != "*" && !strings.Contains(rewriteType, contentType) {
+			continue
+		}
+
+		body = rewrite.Pattern.ReplaceAll(body, rewrite.Replacement)
+	}
+
+	resp.Body = io.NopCloser(bytes.NewReader(body))
+	resp.ContentLength = int64(len(body))
+
+	return nil
+}
+
+func drainBody(b io.ReadCloser) (body []byte, err error) {
+	if b == nil || b == http.NoBody {
+		// No copying needed. Preserve the magic sentinel meaning of NoBody.
+		return nil, nil
+	}
+	var buf bytes.Buffer
+	if _, err = buf.ReadFrom(b); err != nil {
+		return nil, err
+	}
+	if err = b.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
 func (h *forwardHandler) checkRateLimit(addr net.Addr) bool {
 	if h.options.RateLimiter == nil {
 		return true

handler/forward/remote/handler.go

@@ -2,6 +2,7 @@ package remote
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"crypto/tls"
 	"errors"
@@ -179,9 +180,9 @@ func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...hand
 
 func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remoteAddr net.Addr, localAddr net.Addr, log logger.Logger) (err error) {
 	br := bufio.NewReader(rw)
-	var cc net.Conn
 
 	for {
+		var cc net.Conn
 		resp := &http.Response{
 			ProtoMajor: 1,
 			ProtoMinor: 1,
@@ -242,6 +243,7 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 			})
 			log.Debugf("find node for host %s -> %s(%s)", req.Host, target.Name, target.Addr)
 
+			var bodyRewrites []chain.HTTPBodyRewriteSettings
 			if httpSettings := target.Options().HTTP; httpSettings != nil {
 				if auther := httpSettings.Auther; auther != nil {
 					username, password, _ := req.BasicAuth()
@@ -261,7 +263,7 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 					req.Header.Set(k, v)
 				}
 
-				for _, re := range httpSettings.Rewrite {
+				for _, re := range httpSettings.RewriteURL {
 					if re.Pattern.MatchString(req.URL.Path) {
 						if s := re.Pattern.ReplaceAllString(req.URL.Path, re.Replacement); s != "" {
 							req.URL.Path = s
@@ -269,6 +271,8 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 						}
 					}
 				}
+
+				bodyRewrites = httpSettings.RewriteBody
 			}
 
 			cc, err = h.options.Router.Dial(ctx, "tcp", target.Addr)
@@ -331,6 +335,11 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 					log.Trace(string(dump))
 				}
 
+				if err := h.rewriteBody(res, bodyRewrites...); err != nil {
+					log.Errorf("rewrite body: %v", err)
+					return
+				}
+
 				if err = res.Write(rw); err != nil {
 					log.Errorf("write response from node %s(%s): %v", target.Name, target.Addr, err)
 				}
@@ -350,6 +359,50 @@ func (h *forwardHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, remot
 	return
 }
 
+func (h *forwardHandler) rewriteBody(resp *http.Response, rewrites ...chain.HTTPBodyRewriteSettings) error {
+	if resp == nil || len(rewrites) == 0 || resp.ContentLength <= 0 {
+		return nil
+	}
+
+	body, err := drainBody(resp.Body)
+	if err != nil || body == nil {
+		return err
+	}
+
+	contentType, _, _ := strings.Cut(resp.Header.Get("Content-Type"), ";")
+	for _, rewrite := range rewrites {
+		rewriteType := rewrite.Type
+		if rewriteType == "" {
+			rewriteType = "text/html"
+		}
+		if rewriteType != "*" && !strings.Contains(rewriteType, contentType) {
+			continue
+		}
+
+		body = rewrite.Pattern.ReplaceAll(body, rewrite.Replacement)
+	}
+
+	resp.Body = io.NopCloser(bytes.NewReader(body))
+	resp.ContentLength = int64(len(body))
+
+	return nil
+}
+
+func drainBody(b io.ReadCloser) (body []byte, err error) {
+	if b == nil || b == http.NoBody {
+		// No copying needed. Preserve the magic sentinel meaning of NoBody.
+		return nil, nil
+	}
+	var buf bytes.Buffer
+	if _, err = buf.ReadFrom(b); err != nil {
+		return nil, err
+	}
+	if err = b.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
 func (h *forwardHandler) checkRateLimit(addr net.Addr) bool {
 	if h.options.RateLimiter == nil {
 		return true