57 lines
1.7 KiB
Go
57 lines
1.7 KiB
Go
// Copyright (c) 2025-2026 Probo Inc <hello@getprobo.com>.
|
|
//
|
|
// Permission to use, copy, modify, and/or distribute this software for any
|
|
// purpose with or without fee is hereby granted, provided that the above
|
|
// copyright notice and this permission notice appear in all copies.
|
|
//
|
|
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
|
|
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
|
|
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
|
|
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
|
|
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
|
|
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
|
|
// PERFORMANCE OF THIS SOFTWARE.
|
|
|
|
package slack
|
|
|
|
import (
|
|
"crypto/hmac"
|
|
"crypto/sha256"
|
|
"encoding/hex"
|
|
"fmt"
|
|
"strconv"
|
|
"time"
|
|
)
|
|
|
|
// VerifySignature implements the verification algorithm described in https://api.slack.com/authentication/verifying-requests-from-slack
|
|
func VerifySignature(signingSecret, timestamp, signature string, body []byte) error {
|
|
// Check timestamp to prevent replay attacks
|
|
ts, err := strconv.ParseInt(timestamp, 10, 64)
|
|
if err != nil {
|
|
return fmt.Errorf("invalid timestamp: %w", err)
|
|
}
|
|
|
|
now := time.Now().Unix()
|
|
if abs(now-ts) > 60*5 { // 5 minutes
|
|
return fmt.Errorf("request timestamp too old")
|
|
}
|
|
|
|
baseString := fmt.Sprintf("v0:%s:%s", timestamp, body)
|
|
h := hmac.New(sha256.New, []byte(signingSecret))
|
|
h.Write([]byte(baseString))
|
|
expected := "v0=" + hex.EncodeToString(h.Sum(nil))
|
|
|
|
if !hmac.Equal([]byte(expected), []byte(signature)) {
|
|
return fmt.Errorf("signature mismatch")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func abs(n int64) int64 {
|
|
if n < 0 {
|
|
return -n
|
|
}
|
|
return n
|
|
}
|