From e5c4a6a8d1e06a21bd3e3139d89f02c33dc9d275 Mon Sep 17 00:00:00 2001
From: Mayank Pande <mayankpande88@gmail.com>
Date: Thu, 4 Apr 2024 23:06:50 +0530
Subject: [PATCH] fix: fix for host header parsing

---
 containers/container.go  |  4 ++--
 containers/l7.go         |  6 +++---
 ebpftracer/l7/http.go    | 32 ++++++++++++++++++++++++--------
 ebpftracer/l7/l7_test.go |  6 ------
 4 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/containers/container.go b/containers/container.go
index 01ed8a6f..17f64a26 100644
--- a/containers/container.go
+++ b/containers/container.go
@@ -610,9 +610,9 @@ func (c *Container) onL7Request(pid uint32, fd uint64, timestamp uint64, r *l7.R
 	}
 
 	if conn.dstWorkload.Namespace == "external" && (r.Protocol == l7.ProtocolHTTP || r.Protocol == l7.ProtocolHTTP2) {
-		request, error := l7.ParseHttpRequest(string(r.Payload))
+		host, error := l7.ParseHostFromHttpRequest(string(r.Payload))
 		if error == nil {
-			conn.dstWorkload.Name = request.Host
+			conn.dstWorkload.Name = host
 		}
 	}
 	stats := c.l7Stats.get(r.Protocol, conn.Dest, conn.ActualDest, r, conn.srcWorkload, conn.dstWorkload, conn.actualDestWorkload)
diff --git a/containers/l7.go b/containers/l7.go
index 2ec65278..2fb5be74 100644
--- a/containers/l7.go
+++ b/containers/l7.go
@@ -72,9 +72,9 @@ func (s L7Stats) get(protocol l7.Protocol, destination, actualDestination netadd
 			constLabels["path"] = path
 			constLabels["method"] = method
 			if dstWorkload.Namespace == "external" {
-				request, error := l7.ParseHttpRequest(string(r.Payload))
-				if error == nil {
-					constLabels["destination_workload_name"] = request.Host
+				host, err := l7.ParseHostFromHttpRequest(string(r.Payload))
+				if err == nil {
+					constLabels["destination_workload_name"] = host
 				}
 			}
 			hOpts := L7Latency[protocol]
diff --git a/ebpftracer/l7/http.go b/ebpftracer/l7/http.go
index a5f31be8..64ff3dfc 100644
--- a/ebpftracer/l7/http.go
+++ b/ebpftracer/l7/http.go
@@ -1,11 +1,10 @@
 package l7
 
 import (
-	"bufio"
 	"bytes"
 	"encoding/base64"
+	"errors"
 	"log"
-	"net/http"
 	"regexp"
 	"strings"
 )
@@ -51,14 +50,31 @@ func ParseHttpAndRest(payload []byte) (string, string, string, string) {
 	return string(method), string(uri), string(headers), string(d)
 }
 
-func ParseHttpRequest(request string) (*http.Request, error) {
-	request = strings.ReplaceAll(request, "\\n", "\r\n")
-	req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(request)))
-	if err != nil {
-		return nil, err
+func ParseHostFromHttpRequest(request string) (string, error) {
+	// Split the request string into lines
+	lines := strings.Split(request, "\n")
+
+	// Search for the Host header within the lines
+	var host string
+	for _, line := range lines {
+		if strings.HasPrefix(line, "Host:") {
+			parts := strings.SplitN(line, ": ", 2)
+			if len(parts) == 2 {
+				host = parts[1]
+				break
+			}
+		}
+	}
+
+	// Check if the Host header is found
+	if host == "" {
+		err := errors.New("host header not found")
+		return "", err
 	}
-	return req, nil
+
+	return host, nil
 }
+
 func SanitizeString(input string) string {
 	// Regular expression patterns to match various sensitive data formats
 	sensitivePatterns := []*regexp.Regexp{
diff --git a/ebpftracer/l7/l7_test.go b/ebpftracer/l7/l7_test.go
index aa47237b..6c1f60a7 100644
--- a/ebpftracer/l7/l7_test.go
+++ b/ebpftracer/l7/l7_test.go
@@ -88,9 +88,3 @@ func TestParseMongo(t *testing.T) {
 	binary.LittleEndian.PutUint32(payload[mongoHeaderLength+mongoSectionKindLength:], dataSize+1)
 	assert.Equal(t, `<truncated>`, ParseMongo(payload))
 }
-
-func TestParseRequest(t *testing.T) {
-	m, _ := ParseHttpRequest(`HEAD /1 HTTP/1.1\nHost: 127.0.0.1\nUser-Agent: curl/8.0.1\nAccept: */*\n\nxzxxxxxxzx`)
-	assert.Equal(t, "HEAD", m.Method)
-	assert.Equal(t, "127.0.0.1", m.Host)
-}