mirror of
https://github.com/willnorris/imageproxy.git
synced 2025-02-03 23:10:17 -05:00
11370ac826
Adds: - github.com/kr/http/transport - github.com/sqs/s3 - github.com/sqs/s3/s3util - sourcegraph.com/sourcegraph/s3cache
132 lines
3 KiB
Go
132 lines
3 KiB
Go
// Copyright 2014 The transport Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package transport provides a general-purpose wapper for
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// http.RoundTripper. It implements the pattern of taking a
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// request, modifying a copy, and passing the modified copy to an
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// underlying RoundTripper, including bookkeeping necessary to
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// cancel in-flight requests.
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package transport
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import (
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"errors"
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"io"
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"net/http"
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"sync"
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)
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// Wrapper is an http.RoundTripper that makes HTTP requests,
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// wrapping a base RoundTripper and altering every outgoing
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// request in some way.
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type Wrapper struct {
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// Modify alters the request as needed.
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Modify func(*http.Request) error
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// Base is the base RoundTripper used to make HTTP requests.
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// If nil, http.DefaultTransport is used.
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Base http.RoundTripper
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mu sync.Mutex // guards modReq
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modReq map[*http.Request]*http.Request // original -> modified
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}
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// RoundTrip provides a copy of req
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// to the underlying RoundTripper,
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// altered in some way by Modify.
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func (t *Wrapper) RoundTrip(req *http.Request) (*http.Response, error) {
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if t.Modify == nil {
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return nil, errors.New("transport: Wrapper's Modify is nil")
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}
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req2 := cloneRequest(req) // per RoundTripper contract
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err := t.Modify(req2)
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if err != nil {
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return nil, err
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}
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t.setModReq(req, req2)
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res, err := t.base().RoundTrip(req2)
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if err != nil {
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t.setModReq(req, nil)
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return nil, err
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}
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res.Body = &onEOFReader{
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rc: res.Body,
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fn: func() { t.setModReq(req, nil) },
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}
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return res, nil
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}
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// CancelRequest cancels an in-flight request by closing its connection.
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func (t *Wrapper) CancelRequest(req *http.Request) {
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type canceler interface {
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CancelRequest(*http.Request)
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}
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if cr, ok := t.base().(canceler); ok {
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t.mu.Lock()
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modReq := t.modReq[req]
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delete(t.modReq, req)
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t.mu.Unlock()
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cr.CancelRequest(modReq)
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}
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}
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func (t *Wrapper) base() http.RoundTripper {
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if t.Base != nil {
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return t.Base
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}
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return http.DefaultTransport
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}
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func (t *Wrapper) setModReq(orig, mod *http.Request) {
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t.mu.Lock()
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defer t.mu.Unlock()
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if t.modReq == nil {
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t.modReq = make(map[*http.Request]*http.Request)
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}
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if mod == nil {
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delete(t.modReq, orig)
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} else {
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t.modReq[orig] = mod
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}
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}
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// cloneRequest returns a clone of the provided *http.Request.
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// The clone is a shallow copy of the struct and its Header map.
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func cloneRequest(r *http.Request) *http.Request {
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// shallow copy of the struct
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r2 := new(http.Request)
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*r2 = *r
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// deep copy of the Header
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r2.Header = make(http.Header, len(r.Header))
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for k, s := range r.Header {
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r2.Header[k] = append([]string(nil), s...)
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}
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return r2
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}
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type onEOFReader struct {
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rc io.ReadCloser
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fn func()
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}
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func (r *onEOFReader) Read(p []byte) (n int, err error) {
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n, err = r.rc.Read(p)
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if err == io.EOF {
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r.runFunc()
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}
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return
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}
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func (r *onEOFReader) Close() error {
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err := r.rc.Close()
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r.runFunc()
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return err
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}
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func (r *onEOFReader) runFunc() {
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if fn := r.fn; fn != nil {
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fn()
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r.fn = nil
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}
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}
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