From 40dec17b5c8fd7e79e7a0a397311d68a0587f095 Mon Sep 17 00:00:00 2001 From: Snowball_233 Date: Sat, 21 Jun 2025 04:09:03 +0800 Subject: [PATCH] Fix Feishu webhook signature verification (#34788) # Fix Feishu Webhook Signature Verification This PR implements proper signature verification for Feishu (Lark) webhooks according to the [official documentation](https://open.feishu.cn/document/client-docs/bot-v3/add-custom-bot). ## Changes - Implemented the `GenSign` function based on Feishu's official Go sample code - Modified the webhook request creation to include timestamp and signature in the payload when a secret is configured - Fixed the signature generation algorithm to properly use HMAC-SHA256 with the correct string format ## Implementation Details The signature verification works as follows: 1. When a webhook secret is provided, a timestamp is generated 2. The signature string is created using `timestamp + "\n" + secret` 3. The HMAC-SHA256 algorithm is applied to an empty string using the signature string as the key 4. The result is Base64 encoded to produce the final signature 5. Both timestamp and signature are added to the payload According to Feishu's documentation, the timestamp must be within 1 hour (3600 seconds) of the current time to be considered valid. ## Security Note Feishu emphasizes the importance of keeping webhook URLs secure. Do not disclose them on GitHub, blogs, or any public sites to prevent unauthorized use. ## References - [Feishu Custom Bot Documentation](https://open.feishu.cn/document/client-docs/bot-v3/add-custom-bot) --------- Co-authored-by: hiifong Co-authored-by: wxiaoguang --- services/webhook/feishu.go | 36 ++++++++++++++++++++++++++++----- services/webhook/feishu_test.go | 6 +++++- services/webhook/payloader.go | 3 +++ 3 files changed, 39 insertions(+), 6 deletions(-) diff --git a/services/webhook/feishu.go b/services/webhook/feishu.go index c7d2309ac4..b6ee80c44c 100644 --- a/services/webhook/feishu.go +++ b/services/webhook/feishu.go @@ -5,9 +5,13 @@ package webhook import ( "context" + "crypto/hmac" + "crypto/sha256" + "encoding/base64" "fmt" "net/http" "strings" + "time" webhook_model "code.gitea.io/gitea/models/webhook" "code.gitea.io/gitea/modules/git" @@ -16,10 +20,12 @@ import ( ) type ( - // FeishuPayload represents + // FeishuPayload represents the payload for Feishu webhook FeishuPayload struct { - MsgType string `json:"msg_type"` // text / post / image / share_chat / interactive / file /audio / media - Content struct { + Timestamp int64 `json:"timestamp,omitempty"` // Unix timestamp for signature verification + Sign string `json:"sign,omitempty"` // Signature for verification + MsgType string `json:"msg_type"` // text / post / image / share_chat / interactive / file /audio / media + Content struct { Text string `json:"text"` } `json:"content"` } @@ -184,9 +190,29 @@ func (feishuConvertor) WorkflowJob(p *api.WorkflowJobPayload) (FeishuPayload, er return newFeishuTextPayload(text), nil } +// feishuGenSign generates a signature for Feishu webhook +// https://open.feishu.cn/document/client-docs/bot-v3/add-custom-bot +func feishuGenSign(secret string, timestamp int64) string { + // key="{timestamp}\n{secret}", then hmac-sha256, then base64 encode + stringToSign := fmt.Sprintf("%d\n%s", timestamp, secret) + h := hmac.New(sha256.New, []byte(stringToSign)) + return base64.StdEncoding.EncodeToString(h.Sum(nil)) +} + func newFeishuRequest(_ context.Context, w *webhook_model.Webhook, t *webhook_model.HookTask) (*http.Request, []byte, error) { - var pc payloadConvertor[FeishuPayload] = feishuConvertor{} - return newJSONRequest(pc, w, t, true) + payload, err := newPayload(feishuConvertor{}, []byte(t.PayloadContent), t.EventType) + if err != nil { + return nil, nil, err + } + + // Add timestamp and signature if secret is provided + if w.Secret != "" { + timestamp := time.Now().Unix() + payload.Timestamp = timestamp + payload.Sign = feishuGenSign(w.Secret, timestamp) + } + + return prepareJSONRequest(payload, w, t, false /* no default headers */) } func init() { diff --git a/services/webhook/feishu_test.go b/services/webhook/feishu_test.go index c4249bdb30..7e200ea132 100644 --- a/services/webhook/feishu_test.go +++ b/services/webhook/feishu_test.go @@ -168,6 +168,7 @@ func TestFeishuJSONPayload(t *testing.T) { URL: "https://feishu.example.com/", Meta: `{}`, HTTPMethod: "POST", + Secret: "secret", } task := &webhook_model.HookTask{ HookID: hook.ID, @@ -183,10 +184,13 @@ func TestFeishuJSONPayload(t *testing.T) { assert.Equal(t, "POST", req.Method) assert.Equal(t, "https://feishu.example.com/", req.URL.String()) - assert.Equal(t, "sha256=", req.Header.Get("X-Hub-Signature-256")) assert.Equal(t, "application/json", req.Header.Get("Content-Type")) var body FeishuPayload err = json.NewDecoder(req.Body).Decode(&body) assert.NoError(t, err) assert.Equal(t, "[test/repo:test] \r\n[2020558](http://localhost:3000/test/repo/commit/2020558fe2e34debb818a514715839cabd25e778) commit message - user1\r\n[2020558](http://localhost:3000/test/repo/commit/2020558fe2e34debb818a514715839cabd25e778) commit message - user1", body.Content.Text) + assert.Equal(t, feishuGenSign(hook.Secret, body.Timestamp), body.Sign) + + // a separate sign test, the result is generated by official python code, so the algo must be correct + assert.Equal(t, "rWZ84lcag1x9aBFhn1gtV4ZN+4gme3pilfQNMk86vKg=", feishuGenSign("a", 1)) } diff --git a/services/webhook/payloader.go b/services/webhook/payloader.go index c25d700c23..b607bf3250 100644 --- a/services/webhook/payloader.go +++ b/services/webhook/payloader.go @@ -95,7 +95,10 @@ func newJSONRequest[T any](pc payloadConvertor[T], w *webhook_model.Webhook, t * if err != nil { return nil, nil, err } + return prepareJSONRequest(payload, w, t, withDefaultHeaders) +} +func prepareJSONRequest[T any](payload T, w *webhook_model.Webhook, t *webhook_model.HookTask, withDefaultHeaders bool) (*http.Request, []byte, error) { body, err := json.MarshalIndent(payload, "", " ") if err != nil { return nil, nil, err