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Harden webhook example request validation #4

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rekurt merged 1 commit into from
Apr 7, 2026
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Harden webhook example request validation #4

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22 changes: 20 additions & 2 deletions examples/webhook/main.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package main

import (
"crypto/subtle"
"encoding/json"
"fmt"
"io"
Expand All @@ -17,12 +18,17 @@
// Minimal webhook receiver: starts HTTP server, parses updates from YM and replies via SendToChat.
// Env:
// YM_TOKEN (required), YM_REPLY_CHAT (optional default from incoming update),
// YM_WEBHOOK_SECRET (required, value expected in X-Webhook-Secret header),
// YM_PORT (default 8080).
func main() {
token := os.Getenv("YM_TOKEN")
if token == "" {
log.Fatal("YM_TOKEN is required")
}
webhookSecret := os.Getenv("YM_WEBHOOK_SECRET")
if webhookSecret == "" {
log.Fatal("YM_WEBHOOK_SECRET is required")
}
port := os.Getenv("YM_PORT")
if port == "" {
port = "8080"
Expand All @@ -35,10 +41,22 @@

http.HandleFunc("/webhook", func(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
body, _ := io.ReadAll(r.Body)
if subtle.ConstantTimeCompare([]byte(r.Header.Get("X-Webhook-Secret")), []byte(webhookSecret)) != 1 {
http.Error(w, "unauthorized", http.StatusUnauthorized)

return
}

r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
body, err := io.ReadAll(r.Body)
if err != nil {
http.Error(w, "bad request", http.StatusBadRequest)

return
}

var upd ym.Update
if err := json.Unmarshal(body, &upd); err != nil {

Check failure on line 59 in examples/webhook/main.go

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shadow: declaration of "err" shadows declaration at line 51 (govet)
http.Error(w, "bad request", http.StatusBadRequest)

return
Expand All @@ -52,7 +70,7 @@
target = ym.ChatID(replyChat)
}

_, err := s.Messages.SendToChat(r.Context(), target, "echo: "+upd.Text, &messages.SendMessageOptions{

Check failure on line 73 in examples/webhook/main.go

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GitHub Actions / Lint 

shadow: declaration of "err" shadows declaration at line 51 (govet)
ReplyToMessageID: fmt.Sprintf("%d", upd.MessageID),
})
if err != nil {
Expand All @@ -61,7 +79,7 @@
}

w.WriteHeader(http.StatusOK)
_, err := w.Write([]byte(`{"ok":true}`))
_, err = w.Write([]byte(`{"ok":true}`))
if err != nil {
log.Printf("write failed: %v", err)

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