gitea/services/webhook/feishu.go
Snowball_233 40dec17b5c
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 <i@hiif.ong>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
2025-06-20 13:09:03 -07:00

220 lines
7.6 KiB
Go

// Copyright 2020 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
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"
api "code.gitea.io/gitea/modules/structs"
webhook_module "code.gitea.io/gitea/modules/webhook"
)
type (
// FeishuPayload represents the payload for Feishu webhook
FeishuPayload 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"`
}
)
func newFeishuTextPayload(text string) FeishuPayload {
return FeishuPayload{
MsgType: "text",
Content: struct {
Text string `json:"text"`
}{
Text: strings.TrimSpace(text),
},
}
}
type feishuConvertor struct{}
// Create implements PayloadConvertor Create method
func (fc feishuConvertor) Create(p *api.CreatePayload) (FeishuPayload, error) {
// created tag/branch
refName := git.RefName(p.Ref).ShortName()
text := fmt.Sprintf("[%s] %s %s created", p.Repo.FullName, p.RefType, refName)
return newFeishuTextPayload(text), nil
}
// Delete implements PayloadConvertor Delete method
func (fc feishuConvertor) Delete(p *api.DeletePayload) (FeishuPayload, error) {
// created tag/branch
refName := git.RefName(p.Ref).ShortName()
text := fmt.Sprintf("[%s] %s %s deleted", p.Repo.FullName, p.RefType, refName)
return newFeishuTextPayload(text), nil
}
// Fork implements PayloadConvertor Fork method
func (fc feishuConvertor) Fork(p *api.ForkPayload) (FeishuPayload, error) {
text := fmt.Sprintf("%s is forked to %s", p.Forkee.FullName, p.Repo.FullName)
return newFeishuTextPayload(text), nil
}
// Push implements PayloadConvertor Push method
func (fc feishuConvertor) Push(p *api.PushPayload) (FeishuPayload, error) {
var (
branchName = git.RefName(p.Ref).ShortName()
commitDesc string
)
text := fmt.Sprintf("[%s:%s] %s\r\n", p.Repo.FullName, branchName, commitDesc)
// for each commit, generate attachment text
for i, commit := range p.Commits {
var authorName string
if commit.Author != nil {
authorName = " - " + commit.Author.Name
}
text += fmt.Sprintf("[%s](%s) %s", commit.ID[:7], commit.URL,
strings.TrimRight(commit.Message, "\r\n")) + authorName
// add linebreak to each commit but the last
if i < len(p.Commits)-1 {
text += "\r\n"
}
}
return newFeishuTextPayload(text), nil
}
// Issue implements PayloadConvertor Issue method
func (fc feishuConvertor) Issue(p *api.IssuePayload) (FeishuPayload, error) {
title, link, by, operator, result, assignees := getIssuesInfo(p)
if assignees != "" {
if p.Action == api.HookIssueAssigned || p.Action == api.HookIssueUnassigned || p.Action == api.HookIssueMilestoned {
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, result, assignees, p.Issue.Body)), nil
}
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, assignees, p.Issue.Body)), nil
}
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, p.Issue.Body)), nil
}
// IssueComment implements PayloadConvertor IssueComment method
func (fc feishuConvertor) IssueComment(p *api.IssueCommentPayload) (FeishuPayload, error) {
title, link, by, operator := getIssuesCommentInfo(p)
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, p.Comment.Body)), nil
}
// PullRequest implements PayloadConvertor PullRequest method
func (fc feishuConvertor) PullRequest(p *api.PullRequestPayload) (FeishuPayload, error) {
title, link, by, operator, result, assignees := getPullRequestInfo(p)
if assignees != "" {
if p.Action == api.HookIssueAssigned || p.Action == api.HookIssueUnassigned || p.Action == api.HookIssueMilestoned {
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, result, assignees, p.PullRequest.Body)), nil
}
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, assignees, p.PullRequest.Body)), nil
}
return newFeishuTextPayload(fmt.Sprintf("%s\n%s\n%s\n%s\n\n%s", title, link, by, operator, p.PullRequest.Body)), nil
}
// Review implements PayloadConvertor Review method
func (fc feishuConvertor) Review(p *api.PullRequestPayload, event webhook_module.HookEventType) (FeishuPayload, error) {
action, err := parseHookPullRequestEventType(event)
if err != nil {
return FeishuPayload{}, err
}
title := fmt.Sprintf("[%s] Pull request review %s : #%d %s", p.Repository.FullName, action, p.Index, p.PullRequest.Title)
text := p.Review.Content
return newFeishuTextPayload(title + "\r\n\r\n" + text), nil
}
// Repository implements PayloadConvertor Repository method
func (fc feishuConvertor) Repository(p *api.RepositoryPayload) (FeishuPayload, error) {
var text string
switch p.Action {
case api.HookRepoCreated:
text = fmt.Sprintf("[%s] Repository created", p.Repository.FullName)
return newFeishuTextPayload(text), nil
case api.HookRepoDeleted:
text = fmt.Sprintf("[%s] Repository deleted", p.Repository.FullName)
return newFeishuTextPayload(text), nil
}
return FeishuPayload{}, nil
}
// Wiki implements PayloadConvertor Wiki method
func (fc feishuConvertor) Wiki(p *api.WikiPayload) (FeishuPayload, error) {
text, _, _ := getWikiPayloadInfo(p, noneLinkFormatter, true)
return newFeishuTextPayload(text), nil
}
// Release implements PayloadConvertor Release method
func (fc feishuConvertor) Release(p *api.ReleasePayload) (FeishuPayload, error) {
text, _ := getReleasePayloadInfo(p, noneLinkFormatter, true)
return newFeishuTextPayload(text), nil
}
func (fc feishuConvertor) Package(p *api.PackagePayload) (FeishuPayload, error) {
text, _ := getPackagePayloadInfo(p, noneLinkFormatter, true)
return newFeishuTextPayload(text), nil
}
func (fc feishuConvertor) Status(p *api.CommitStatusPayload) (FeishuPayload, error) {
text, _ := getStatusPayloadInfo(p, noneLinkFormatter, true)
return newFeishuTextPayload(text), nil
}
func (feishuConvertor) WorkflowRun(p *api.WorkflowRunPayload) (FeishuPayload, error) {
text, _ := getWorkflowRunPayloadInfo(p, noneLinkFormatter, true)
return newFeishuTextPayload(text), nil
}
func (feishuConvertor) WorkflowJob(p *api.WorkflowJobPayload) (FeishuPayload, error) {
text, _ := getWorkflowJobPayloadInfo(p, noneLinkFormatter, true)
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) {
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() {
RegisterWebhookRequester(webhook_module.FEISHU, newFeishuRequest)
}