fix: truncated body dump error

[yuweizzz]

this is the extend of #572 .

The request/response body may be truncated in events, so the 'Content-Length' header value not match the real data length, ReadAll/Close will always raise UnexpectedEOF error. #572 can only fix the real data length is 0, the pr will fix the others.

[cfc4n]

Can you add a unit test? Cover both cases where Content-Length is 0 and not 0.

[yuweizzz]

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
)

func main() {
	// normal
	const body = "abcde"
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
		fmt.Fprintln(w, body)
	}))
	defer ts.Close()
	resp, err := http.Get(ts.URL)
	if err != nil {
		fmt.Println(err)
	}
	defer resp.Body.Close()

	dump, err := httputil.DumpResponse(resp, true)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(string(dump))

	rd := bytes.NewReader(dump)
	buf := bufio.NewReader(rd)
	read_resp, err := http.ReadResponse(buf, nil)
	if err != nil {
		fmt.Println(err)
	}
	data, err := io.ReadAll(read_resp.Body)
	// normal, err is nil
	fmt.Println(data, err)
	fmt.Println("-------------------")

	// normal, content-length is 0
	ts = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
	}))
	defer ts.Close()
	resp, err = http.Get(ts.URL)
	if err != nil {
		fmt.Println(err)
	}
	defer resp.Body.Close()

	dump, err = httputil.DumpResponse(resp, true)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(string(dump))

	rd = bytes.NewReader(dump)
	buf = bufio.NewReader(rd)
	read_resp, err = http.ReadResponse(buf, nil)
	if err != nil {
		fmt.Println(err)
	}
	data, err = io.ReadAll(read_resp.Body)
	// normal, err is nil
	fmt.Println(data, err)
	fmt.Println("-------------------")

	// head method respone, content-length is 6, real length is 0
	ts = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
		fmt.Fprintln(w, body)
	}))
	defer ts.Close()
	resp, err = http.Head(ts.URL)
	if err != nil {
		fmt.Println(err)
	}
	defer resp.Body.Close()

	dump, err = httputil.DumpResponse(resp, true)
	if err != nil {
		fmt.Println(err)
	}
	// head method respone
	fmt.Println(string(dump))

	rd = bytes.NewReader(dump)
	buf = bufio.NewReader(rd)
	read_resp, err = http.ReadResponse(buf, nil)
	if err != nil {
		fmt.Println(err)
	}
	data, err = io.ReadAll(read_resp.Body)
	// head method respone, but DumpResponse required body, err is ErrUnexpectedEOF
	fmt.Println(data, err)
	fmt.Println("-------------------")

	// chunked respone, no content-length
	ts1 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
		w.Header().Set("Content-Length", "")
		fmt.Fprintln(w, body)
	}))
	defer ts1.Close()
	resp, err = http.Get(ts1.URL)
	if err != nil {
		fmt.Println(err)
	}
	defer resp.Body.Close()

	dump, err = httputil.DumpResponse(resp, true)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(string(dump))

	rd = bytes.NewReader(dump)
	buf = bufio.NewReader(rd)
	read_resp, err = http.ReadResponse(buf, nil)
	if err != nil {
		fmt.Println(err)
	}
	data, err = io.ReadAll(read_resp.Body)
	// chunked respone, err is nil
	fmt.Println(data, err)
	fmt.Println("-------------------")

	// truncated respone, real data length smaller than content-length
	t := "HTTP/1.1 200 OK\r\nContent-Length: 9999\r\nContent-Type: text/plain; charset=utf-8\r\nDate: Wed, 19 Jul 1972 19:00:00 GMT\r\n\r\nabcde\n"
	rd = bytes.NewReader([]byte(t))
	buf = bufio.NewReader(rd)
	read_resp, err = http.ReadResponse(buf, nil)
	if err != nil {
		fmt.Println(err)
	}
	data, err = io.ReadAll(read_resp.Body)
	// truncated respone, err is ErrUnexpectedEOF
	fmt.Println(data, err)
}

[cfc4n]

Is the code from lines 108 to 143 merely for parsing packerType?

[cfc4n]

Why is 'false' used here?

[cfc4n]

@yuweizzz Thank you for your contribution. What I mean is "Could you add some unit tests in the PR to verify your code?"

[cfc4n]

Merge this PR first, and I will add unit tests. thanks.