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proxyutil.go
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proxyutil.go
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// Copyright 2015 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/*
Package proxyutil provides functionality for building proxies.
*/
package proxyutil
import (
"bytes"
_ "embed"
"fmt"
"html"
"io"
"io/ioutil"
"net/http"
"regexp"
"strconv"
"strings"
"time"
)
//go:embed template.html
var templateBody string
func NewResponseFromOldResponse(code int, body io.Reader, req *http.Request, oldRsp *http.Response) *http.Response {
// If Content-Type is not text, we will not provide body
// This is to prevent parsing errors in some js/css responses
if !strings.Contains(oldRsp.Header.Get("Content-Type"), "text") {
body = nil
}
return NewResponse(code, body, req)
}
// NewResponse builds new HTTP responses.
// If body is nil, an empty byte.Buffer will be provided to be consistent with
// the guarantees provided by http.Transport and http.Client.
func NewResponse(code int, body io.Reader, req *http.Request) *http.Response {
if body == nil {
body = &bytes.Buffer{}
}
rc, ok := body.(io.ReadCloser)
if !ok {
rc = ioutil.NopCloser(body)
}
headers := http.Header{}
headers["Content-Type"] = []string{"text/html;charset=utf-8"}
res := &http.Response{
StatusCode: code,
Status: fmt.Sprintf("%d %s", code, http.StatusText(code)),
Proto: "HTTP/1.1",
ProtoMajor: 1,
ProtoMinor: 1,
Header: headers,
Body: rc,
Request: req,
}
if req != nil {
res.Close = req.Close
res.Proto = req.Proto
res.ProtoMajor = req.ProtoMajor
res.ProtoMinor = req.ProtoMinor
}
return res
}
// Warning adds an error to the Warning header in the format: 199 "martian"
// "error message" "date".
func Warning(header http.Header, err error) {
date := header.Get("Date")
if date == "" {
date = time.Now().Format(http.TimeFormat)
}
w := fmt.Sprintf(`199 "martian" %q %q`, err.Error(), date)
header.Add("Warning", w)
}
// GetRangeStart returns the byte index of the start of the range, if it has one.
// Returns 0 if the range header is absent, and -1 if the range header is invalid or
// has multi-part ranges.
func GetRangeStart(res *http.Response) int64 {
if res.StatusCode != http.StatusPartialContent {
return 0
}
if strings.Contains(res.Header.Get("Content-Type"), "multipart/byteranges") {
return -1
}
re := regexp.MustCompile(`bytes (\d+)-\d+/\d+`)
matchSlice := re.FindStringSubmatch(res.Header.Get("Content-Range"))
if len(matchSlice) < 2 {
return -1
}
num, err := strconv.ParseInt(matchSlice[1], 10, 64)
if err != nil {
return -1
}
return num
}
func GetPrettyErrorRsp(msg string) string {
msg = html.EscapeString(msg)
return strings.ReplaceAll(templateBody, "{{content}}", msg)
}