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// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package gitea
import (
"bytes"
"crypto/hmac"
"crypto/sha256"
"encoding/hex"
"io"
"net/http"
)
// VerifyWebhookSignature verifies that a payload matches the X-Gitea-Signature based on a secret
func VerifyWebhookSignature(secret, expected string, payload []byte) (bool, error) {
hash := hmac.New(sha256.New, []byte(secret))
if _, err := hash.Write(payload); err != nil {
return false, err
}
expectedSum, err := hex.DecodeString(expected)
if err != nil {
return false, err
}
return hmac.Equal(hash.Sum(nil), expectedSum), nil
}
// VerifyWebhookSignatureMiddleware is a http.Handler for verifying X-Gitea-Signature on incoming webhooks
func VerifyWebhookSignatureMiddleware(secret string) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var b bytes.Buffer
if _, err := io.Copy(&b, r.Body); err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
expected := r.Header.Get("X-Gitea-Signature")
if expected == "" {
http.Error(w, "no signature found", http.StatusBadRequest)
return
}
ok, err := VerifyWebhookSignature(secret, expected, b.Bytes())
if err != nil {
http.Error(w, err.Error(), http.StatusUnauthorized)
return
}
if !ok {
http.Error(w, "invalid payload", http.StatusUnauthorized)
return
}
r.Body = io.NopCloser(&b)
next.ServeHTTP(w, r)
})
}
}
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