response.go

// From Go net/http package
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Modified by domosekai 2020

package main

import (
	"bufio"
	"fmt"
	"io"
	"net/http"
	"net/textproto"
	"strconv"
	"strings"

	"golang.org/x/net/http/httpguts"
)

type badStringError struct {
	what string
	str  string
}

func (e *badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }

func readResponseStatus(r *bufio.Reader) (*http.Response, error) {
	tp := textproto.NewReader(r)
	resp := &http.Response{}

	// Parse the first line of the response.
	line, err := tp.ReadLine()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return nil, err
	}
	if i := strings.IndexByte(line, ' '); i == -1 {
		return nil, &badStringError{"malformed HTTP response", line}
	} else {
		resp.Proto = line[:i]
		resp.Status = strings.TrimLeft(line[i+1:], " ")
	}
	statusCode := resp.Status
	if i := strings.IndexByte(resp.Status, ' '); i != -1 {
		statusCode = resp.Status[:i]
	}
	if len(statusCode) != 3 {
		return nil, &badStringError{"malformed HTTP status code", statusCode}
	}
	resp.StatusCode, err = strconv.Atoi(statusCode)
	if err != nil || resp.StatusCode < 0 {
		return nil, &badStringError{"malformed HTTP status code", statusCode}
	}
	var ok bool
	if resp.ProtoMajor, resp.ProtoMinor, ok = http.ParseHTTPVersion(resp.Proto); !ok {
		return nil, &badStringError{"malformed HTTP version", resp.Proto}
	}

	return resp, nil
}

// Determine whether to hang up after sending a request and body, or
// receiving a response and body
// 'header' is the request headers
func shouldClose(major, minor int, header http.Header) bool {
	if major < 1 {
		return true
	}

	conv := header["Connection"]
	hasClose := httpguts.HeaderValuesContainsToken(conv, "close")
	if major == 1 && minor == 0 {
		return hasClose || !httpguts.HeaderValuesContainsToken(conv, "keep-alive")
	}

	return hasClose
}