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/*
GoToSocial
Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package transport
import (
"context"
"crypto"
"crypto/x509"
"errors"
"io"
"net/http"
"net/url"
"strings"
"sync"
"time"
errorsv2 "codeberg.org/gruf/go-errors/v2"
"codeberg.org/gruf/go-kv"
"github.com/go-fed/httpsig"
"github.com/superseriousbusiness/activity/pub"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/httpclient"
"github.com/superseriousbusiness/gotosocial/internal/log"
)
// Transport wraps the pub.Transport interface with some additional functionality for fetching remote media.
//
// Since the transport has the concept of 'shortcuts' for fetching data locally rather than remotely, it is
// not *always* the case that calling a Transport function does an http call, but it usually will for remote
// hosts or resources for which a shortcut isn't provided by the transport controller (also in this package).
type Transport interface {
pub.Transport
// DereferenceMedia fetches the given media attachment IRI, returning the reader and filesize.
DereferenceMedia(ctx context.Context, iri *url.URL) (io.ReadCloser, int64, error)
// DereferenceInstance dereferences remote instance information, first by checking /api/v1/instance, and then by checking /.well-known/nodeinfo.
DereferenceInstance(ctx context.Context, iri *url.URL) (*gtsmodel.Instance, error)
// Finger performs a webfinger request with the given username and domain, and returns the bytes from the response body.
Finger(ctx context.Context, targetUsername string, targetDomains string) ([]byte, error)
}
// transport implements the Transport interface
type transport struct {
controller *controller
pubKeyID string
privkey crypto.PrivateKey
signerExp time.Time
getSigner httpsig.Signer
postSigner httpsig.Signer
signerMu sync.Mutex
}
// GET will perform given http request using transport client, retrying on certain preset errors, or if status code is among retryOn.
func (t *transport) GET(r *http.Request, retryOn ...int) (*http.Response, error) {
if r.Method != http.MethodGet {
return nil, errors.New("must be GET request")
}
return t.do(r, func(r *http.Request) error {
return t.signGET(r)
}, retryOn...)
}
// POST will perform given http request using transport client, retrying on certain preset errors, or if status code is among retryOn.
func (t *transport) POST(r *http.Request, body []byte, retryOn ...int) (*http.Response, error) {
if r.Method != http.MethodPost {
return nil, errors.New("must be POST request")
}
return t.do(r, func(r *http.Request) error {
return t.signPOST(r, body)
}, retryOn...)
}
func (t *transport) do(r *http.Request, signer func(*http.Request) error, retryOn ...int) (*http.Response, error) {
const maxRetries = 5
backoff := time.Second * 2
// Start a log entry for this request
l := log.WithFields(kv.Fields{
{"pubKeyID", t.pubKeyID},
{"method", r.Method},
{"url", r.URL.String()},
}...)
for i := 0; i < maxRetries; i++ {
// Reset signing header fields
now := t.controller.clock.Now().UTC()
r.Header.Set("Date", now.Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
r.Header.Del("Signature")
r.Header.Del("Digest")
// Perform request signing
if err := signer(r); err != nil {
return nil, err
}
l.Infof("performing request")
// Attempt to perform request
rsp, err := t.controller.client.Do(r)
if err == nil { //nolint shutup linter
// TooManyRequest means we need to slow
// down and retry our request. Codes over
// 500 generally indicate temp. outages.
if code := rsp.StatusCode; code < 500 &&
code != http.StatusTooManyRequests &&
!containsInt(retryOn, rsp.StatusCode) {
return rsp, nil
}
// Generate error from status code for logging
err = errors.New(`http response "` + rsp.Status + `"`)
} else if errorsv2.Is(err,
context.DeadlineExceeded,
context.Canceled,
httpclient.ErrInvalidRequest,
httpclient.ErrBodyTooLarge,
httpclient.ErrReservedAddr,
) {
// Return on non-retryable errors
return nil, err
} else if strings.Contains(err.Error(), "stopped after 10 redirects") {
// Don't bother if net/http returned after too many redirects
return nil, err
} else if errors.As(err, &x509.UnknownAuthorityError{}) {
// Unknown authority errors we do NOT recover from
return nil, err
}
l.Errorf("backing off for %s after http request error: %v", backoff.String(), err)
select {
// Request ctx cancelled
case <-r.Context().Done():
return nil, r.Context().Err()
// Backoff for some time
case <-time.After(backoff):
backoff *= 2
}
}
return nil, errors.New("transport reached max retries")
}
// signGET will safely sign an HTTP GET request.
func (t *transport) signGET(r *http.Request) (err error) {
t.safesign(func() {
err = t.getSigner.SignRequest(t.privkey, t.pubKeyID, r, nil)
})
return
}
// signPOST will safely sign an HTTP POST request for given body.
func (t *transport) signPOST(r *http.Request, body []byte) (err error) {
t.safesign(func() {
err = t.postSigner.SignRequest(t.privkey, t.pubKeyID, r, body)
})
return
}
// safesign will perform sign function within mutex protection,
// and ensured that httpsig.Signers are up-to-date.
func (t *transport) safesign(sign func()) {
// Perform within mu safety
t.signerMu.Lock()
defer t.signerMu.Unlock()
if now := time.Now(); now.After(t.signerExp) {
const expiry = 120
// Signers have expired and require renewal
t.getSigner, _ = NewGETSigner(expiry)
t.postSigner, _ = NewPOSTSigner(expiry)
t.signerExp = now.Add(time.Second * expiry)
}
// Perform signing
sign()
}
// containsInt checks if slice contains check.
func containsInt(slice []int, check int) bool {
for _, i := range slice {
if i == check {
return true
}
}
return false
}
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