fix #1676

Fix various pagination issues with CHATHISTORY; also undo #491
(msgid munging).

irc/utils/crypto.go

@@ -42,29 +42,6 @@ func GenerateSecretToken() string {
 	return B32Encoder.EncodeToString(buf[:])
 }
 
-// "munge" a secret token to a new value. requirements:
-// 1. MUST be roughly as unlikely to collide with `GenerateSecretToken` outputs
-// as those outputs are with each other
-// 2. SHOULD be deterministic (motivation: if a JOIN line has msgid x,
-// create a deterministic msgid y for the fake HistServ PRIVMSG that "replays" it)
-// 3. SHOULD be in the same "namespace" as `GenerateSecretToken` outputs
-// (same length and character set)
-func MungeSecretToken(token string) (result string) {
-	bytes, err := B32Encoder.DecodeString(token)
-	if err != nil {
-		// this should never happen
-		return GenerateSecretToken()
-	}
-	// add 1 with carrying
-	for i := len(bytes) - 1; 0 <= i; i -= 1 {
-		bytes[i] += 1
-		if bytes[i] != 0 {
-			break
-		} // else: overflow, carry to the next place
-	}
-	return B32Encoder.EncodeToString(bytes)
-}
-
 // securely check if a supplied token matches a stored token
 func SecretTokensMatch(storedToken string, suppliedToken string) bool {
 	// XXX fix a potential gotcha: if the stored token is uninitialized,