148 lines
3.2 KiB
Go
148 lines
3.2 KiB
Go
package transport
|
|
|
|
import (
|
|
"io"
|
|
"net/http"
|
|
"sync"
|
|
)
|
|
|
|
// RequestModifier represents an object which will do an inplace
|
|
// modification of an HTTP request.
|
|
type RequestModifier interface {
|
|
ModifyRequest(*http.Request) error
|
|
}
|
|
|
|
type headerModifier http.Header
|
|
|
|
// NewHeaderRequestModifier returns a new RequestModifier which will
|
|
// add the given headers to a request.
|
|
func NewHeaderRequestModifier(header http.Header) RequestModifier {
|
|
return headerModifier(header)
|
|
}
|
|
|
|
func (h headerModifier) ModifyRequest(req *http.Request) error {
|
|
for k, s := range http.Header(h) {
|
|
req.Header[k] = append(req.Header[k], s...)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// NewTransport creates a new transport which will apply modifiers to
|
|
// the request on a RoundTrip call.
|
|
func NewTransport(base http.RoundTripper, modifiers ...RequestModifier) http.RoundTripper {
|
|
return &transport{
|
|
Modifiers: modifiers,
|
|
Base: base,
|
|
}
|
|
}
|
|
|
|
// transport is an http.RoundTripper that makes HTTP requests after
|
|
// copying and modifying the request
|
|
type transport struct {
|
|
Modifiers []RequestModifier
|
|
Base http.RoundTripper
|
|
|
|
mu sync.Mutex // guards modReq
|
|
modReq map[*http.Request]*http.Request // original -> modified
|
|
}
|
|
|
|
// RoundTrip authorizes and authenticates the request with an
|
|
// access token. If no token exists or token is expired,
|
|
// tries to refresh/fetch a new token.
|
|
func (t *transport) RoundTrip(req *http.Request) (*http.Response, error) {
|
|
req2 := cloneRequest(req)
|
|
for _, modifier := range t.Modifiers {
|
|
if err := modifier.ModifyRequest(req2); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
t.setModReq(req, req2)
|
|
res, err := t.base().RoundTrip(req2)
|
|
if err != nil {
|
|
t.setModReq(req, nil)
|
|
return nil, err
|
|
}
|
|
res.Body = &onEOFReader{
|
|
rc: res.Body,
|
|
fn: func() { t.setModReq(req, nil) },
|
|
}
|
|
return res, nil
|
|
}
|
|
|
|
// CancelRequest cancels an in-flight request by closing its connection.
|
|
func (t *transport) CancelRequest(req *http.Request) {
|
|
type canceler interface {
|
|
CancelRequest(*http.Request)
|
|
}
|
|
if cr, ok := t.base().(canceler); ok {
|
|
t.mu.Lock()
|
|
modReq := t.modReq[req]
|
|
delete(t.modReq, req)
|
|
t.mu.Unlock()
|
|
cr.CancelRequest(modReq)
|
|
}
|
|
}
|
|
|
|
func (t *transport) base() http.RoundTripper {
|
|
if t.Base != nil {
|
|
return t.Base
|
|
}
|
|
return http.DefaultTransport
|
|
}
|
|
|
|
func (t *transport) setModReq(orig, mod *http.Request) {
|
|
t.mu.Lock()
|
|
defer t.mu.Unlock()
|
|
if t.modReq == nil {
|
|
t.modReq = make(map[*http.Request]*http.Request)
|
|
}
|
|
if mod == nil {
|
|
delete(t.modReq, orig)
|
|
} else {
|
|
t.modReq[orig] = mod
|
|
}
|
|
}
|
|
|
|
// cloneRequest returns a clone of the provided *http.Request.
|
|
// The clone is a shallow copy of the struct and its Header map.
|
|
func cloneRequest(r *http.Request) *http.Request {
|
|
// shallow copy of the struct
|
|
r2 := new(http.Request)
|
|
*r2 = *r
|
|
// deep copy of the Header
|
|
r2.Header = make(http.Header, len(r.Header))
|
|
for k, s := range r.Header {
|
|
r2.Header[k] = append([]string(nil), s...)
|
|
}
|
|
|
|
return r2
|
|
}
|
|
|
|
type onEOFReader struct {
|
|
rc io.ReadCloser
|
|
fn func()
|
|
}
|
|
|
|
func (r *onEOFReader) Read(p []byte) (n int, err error) {
|
|
n, err = r.rc.Read(p)
|
|
if err == io.EOF {
|
|
r.runFunc()
|
|
}
|
|
return
|
|
}
|
|
|
|
func (r *onEOFReader) Close() error {
|
|
err := r.rc.Close()
|
|
r.runFunc()
|
|
return err
|
|
}
|
|
|
|
func (r *onEOFReader) runFunc() {
|
|
if fn := r.fn; fn != nil {
|
|
fn()
|
|
r.fn = nil
|
|
}
|
|
}
|