forgejo/modules/activitypub/client.go
Gergely Nagy cd17eb0fa7
activitypub: Sign the Host header too
Mastodon with `AUTHORIZED_FETCH` enabled requires the `Host` header to
be signed too, add it to the default for `setting.Federation.GetHeaders`
and `setting.Federation.PostHeaders`.

For this to work, we need to sign the request later: not immediately
after `NewRequest`, but just before sending them out with `client.Do`.
Doing so also lets us use `setting.Federation.GetHeaders` (we were using
`.PostHeaders` even for GET requests before).

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>
2024-08-04 23:57:48 +02:00

187 lines
5.3 KiB
Go

// Copyright 2022 The Gitea Authors. All rights reserved.
// Copyright 2024 The Forgejo Authors. All rights reserved.
// SPDX-License-Identifier: MIT
// TODO: Think about whether this should be moved to services/activitypub (compare to exosy/services/activitypub/client.go)
package activitypub
import (
"bytes"
"context"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"fmt"
"io"
"net/http"
"strings"
"time"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/proxy"
"code.gitea.io/gitea/modules/setting"
"github.com/go-fed/httpsig"
)
const (
// ActivityStreamsContentType const
ActivityStreamsContentType = `application/ld+json; profile="https://www.w3.org/ns/activitystreams"`
httpsigExpirationTime = 60
)
func CurrentTime() string {
return time.Now().UTC().Format(http.TimeFormat)
}
func containsRequiredHTTPHeaders(method string, headers []string) error {
var hasRequestTarget, hasDate, hasDigest, hasHost bool
for _, header := range headers {
hasRequestTarget = hasRequestTarget || header == httpsig.RequestTarget
hasDate = hasDate || header == "Date"
hasDigest = hasDigest || header == "Digest"
hasHost = hasHost || header == "Host"
}
if !hasRequestTarget {
return fmt.Errorf("missing http header for %s: %s", method, httpsig.RequestTarget)
} else if !hasDate {
return fmt.Errorf("missing http header for %s: Date", method)
} else if !hasHost {
return fmt.Errorf("missing http header for %s: Host", method)
} else if !hasDigest && method != http.MethodGet {
return fmt.Errorf("missing http header for %s: Digest", method)
}
return nil
}
// Client struct
type Client struct {
client *http.Client
algs []httpsig.Algorithm
digestAlg httpsig.DigestAlgorithm
getHeaders []string
postHeaders []string
priv *rsa.PrivateKey
pubID string
}
// NewClient function
func NewClient(ctx context.Context, user *user_model.User, pubID string) (c *Client, err error) {
if err = containsRequiredHTTPHeaders(http.MethodGet, setting.Federation.GetHeaders); err != nil {
return nil, err
} else if err = containsRequiredHTTPHeaders(http.MethodPost, setting.Federation.PostHeaders); err != nil {
return nil, err
}
priv, err := GetPrivateKey(ctx, user)
if err != nil {
return nil, err
}
privPem, _ := pem.Decode([]byte(priv))
privParsed, err := x509.ParsePKCS1PrivateKey(privPem.Bytes)
if err != nil {
return nil, err
}
c = &Client{
client: &http.Client{
Transport: &http.Transport{
Proxy: proxy.Proxy(),
},
Timeout: 5 * time.Second,
},
algs: setting.HttpsigAlgs,
digestAlg: httpsig.DigestAlgorithm(setting.Federation.DigestAlgorithm),
getHeaders: setting.Federation.GetHeaders,
postHeaders: setting.Federation.PostHeaders,
priv: privParsed,
pubID: pubID,
}
return c, err
}
// NewRequest function
func (c *Client) newRequest(method string, b []byte, to string) (req *http.Request, err error) {
buf := bytes.NewBuffer(b)
req, err = http.NewRequest(method, to, buf)
if err != nil {
return nil, err
}
req.Header.Add("Accept", "application/json, "+ActivityStreamsContentType)
req.Header.Add("Date", CurrentTime())
req.Header.Add("Host", req.URL.Host)
req.Header.Add("User-Agent", "Gitea/"+setting.AppVer)
req.Header.Add("Content-Type", ActivityStreamsContentType)
return req, err
}
// Post function
func (c *Client) Post(b []byte, to string) (resp *http.Response, err error) {
var req *http.Request
if req, err = c.newRequest(http.MethodPost, b, to); err != nil {
return nil, err
}
signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.postHeaders, httpsig.Signature, httpsigExpirationTime)
if err != nil {
return nil, err
}
if err := signer.SignRequest(c.priv, c.pubID, req, b); err != nil {
return nil, err
}
resp, err = c.client.Do(req)
return resp, err
}
// Create an http GET request with forgejo/gitea specific headers
func (c *Client) Get(to string) (resp *http.Response, err error) {
var req *http.Request
if req, err = c.newRequest(http.MethodGet, nil, to); err != nil {
return nil, err
}
signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.getHeaders, httpsig.Signature, httpsigExpirationTime)
if err != nil {
return nil, err
}
if err := signer.SignRequest(c.priv, c.pubID, req, nil); err != nil {
return nil, err
}
resp, err = c.client.Do(req)
return resp, err
}
// Create an http GET request with forgejo/gitea specific headers
func (c *Client) GetBody(uri string) ([]byte, error) {
response, err := c.Get(uri)
if err != nil {
return nil, err
}
log.Debug("Client: got status: %v", response.Status)
if response.StatusCode != 200 {
err = fmt.Errorf("got non 200 status code for id: %v", uri)
return nil, err
}
defer response.Body.Close()
body, err := io.ReadAll(response.Body)
if err != nil {
return nil, err
}
log.Debug("Client: got body: %v", charLimiter(string(body), 120))
return body, nil
}
// Limit number of characters in a string (useful to prevent log injection attacks and overly long log outputs)
// Thanks to https://www.socketloop.com/tutorials/golang-characters-limiter-example
func charLimiter(s string, limit int) string {
reader := strings.NewReader(s)
buff := make([]byte, limit)
n, _ := io.ReadAtLeast(reader, buff, limit)
if n != 0 {
return fmt.Sprint(string(buff), "...")
}
return s
}