From 6d704b9cd174d0a5827959c5f1897fb12f9ba4c4 Mon Sep 17 00:00:00 2001
From: MetaCubeX <maze.y2b@github.com>
Date: Mon, 2 May 2022 05:10:18 +0800
Subject: [PATCH] feat: sniffer support http

---
 component/sniffer/http_sniffer.go | 109 ++++++++++++++++++++++++++++++
 component/sniffer/quic_sniffer.go |   3 +
 constant/sniffer.go               |   4 +-
 3 files changed, 115 insertions(+), 1 deletion(-)
 create mode 100644 component/sniffer/http_sniffer.go
 create mode 100644 component/sniffer/quic_sniffer.go

diff --git a/component/sniffer/http_sniffer.go b/component/sniffer/http_sniffer.go
new file mode 100644
index 000000000..84ab41032
--- /dev/null
+++ b/component/sniffer/http_sniffer.go
@@ -0,0 +1,109 @@
+package sniffer
+
+import (
+	"bytes"
+	"errors"
+	C "github.com/Dreamacro/clash/constant"
+	"net"
+	"strconv"
+	"strings"
+)
+
+var (
+	// refer to https://pkg.go.dev/net/http@master#pkg-constants
+	methods          = [...]string{"get", "post", "head", "put", "delete", "options", "connect", "patch", "trace"}
+	errNotHTTPMethod = errors.New("not an HTTP method")
+)
+
+type version byte
+
+const (
+	HTTP1 version = iota
+	HTTP2
+)
+
+type HTTPSniffer struct {
+	version version
+	host    string
+}
+
+func (http *HTTPSniffer) Protocol() string {
+	switch http.version {
+	case HTTP1:
+		return "http1"
+	case HTTP2:
+		return "http2"
+	default:
+		return "unknown"
+	}
+}
+
+func (http *HTTPSniffer) SupportNetwork() C.NetWork {
+	return C.TCP
+}
+
+func (http *HTTPSniffer) SniffTCP(bytes []byte) (string, error) {
+	domain, err := SniffHTTP(bytes)
+	if err == nil {
+		return *domain, nil
+	} else {
+		return "", err
+	}
+}
+
+func beginWithHTTPMethod(b []byte) error {
+	for _, m := range &methods {
+		if len(b) >= len(m) && strings.EqualFold(string(b[:len(m)]), m) {
+			return nil
+		}
+
+		if len(b) < len(m) {
+			return ErrNoClue
+		}
+	}
+	return errNotHTTPMethod
+}
+
+func SniffHTTP(b []byte) (*string, error) {
+	if err := beginWithHTTPMethod(b); err != nil {
+		return nil, err
+	}
+
+	_ = &HTTPSniffer{
+		version: HTTP1,
+	}
+
+	headers := bytes.Split(b, []byte{'\n'})
+	for i := 1; i < len(headers); i++ {
+		header := headers[i]
+		if len(header) == 0 {
+			break
+		}
+		parts := bytes.SplitN(header, []byte{':'}, 2)
+		if len(parts) != 2 {
+			continue
+		}
+		key := strings.ToLower(string(parts[0]))
+		if key == "host" {
+			port := 80
+			rawHost := strings.ToLower(string(bytes.TrimSpace(parts[1])))
+			host, rawPort, err := net.SplitHostPort(rawHost)
+			if err != nil {
+				if addrError, ok := err.(*net.AddrError); ok && strings.Contains(addrError.Err, "missing port") {
+					host = rawHost
+				} else {
+					return nil, err
+				}
+			} else if len(rawPort) > 0 {
+				intPort, err := strconv.ParseUint(rawPort, 0, 16)
+				if err != nil {
+					return nil, err
+				}
+				port = int(intPort)
+			}
+			host = net.JoinHostPort(host, strconv.Itoa(port))
+			return &host, nil
+		}
+	}
+	return nil, ErrNoClue
+}
diff --git a/component/sniffer/quic_sniffer.go b/component/sniffer/quic_sniffer.go
new file mode 100644
index 000000000..de78cf821
--- /dev/null
+++ b/component/sniffer/quic_sniffer.go
@@ -0,0 +1,3 @@
+package sniffer
+
+//TODO
diff --git a/constant/sniffer.go b/constant/sniffer.go
index 5454279aa..c19b068cd 100644
--- a/constant/sniffer.go
+++ b/constant/sniffer.go
@@ -11,7 +11,7 @@ const (
 )
 
 var (
-	SnifferList = []SnifferType{TLS}
+	SnifferList = []SnifferType{TLS, HTTP}
 )
 
 type SnifferType int
@@ -20,6 +20,8 @@ func (rt SnifferType) String() string {
 	switch rt {
 	case TLS:
 		return "TLS"
+	case HTTP:
+		return "HTTP"
 	default:
 		return "Unknown"
 	}