Blst Module - Blocklist Management

Andrei Pelinescu-Onciul

iptelorg GmbH

Table of Contents

1. Admin Guide
1. Overview
2. Functions
2.1. blst_add([timeout])
2.2. blst_add_retry_after(min, max)
2.3. blst_del()
2.4. blst_is_blocklisted()
2.5. blst_set_ignore([flags])
2.6. blst_rpl_set_ignore([flags])
2.7. blst_clear_ignore([flags])
2.8. blst_rpl_clear_ignore([flags])

List of Examples

1.1. blst_add usage
1.2. blst_add_retry_after usage
1.3. blst_del usage
1.4. blst_is_blocklisted usage
1.5. blst_set_ignore usage
1.6. blst_clear_ignore usage

Chapter 1. Admin Guide

1. Overview

This module exports blocklist related functions to the script.

2. Functions

2.1.  blst_add([timeout])

Adds the source of the current message to the blocklist for timeout seconds. If timeout is missing or 0 it uses the default blocklist timeout (dst_blocklist_expire).

Example 1.1. blst_add usage

if (src_ip==
    blst_add(30); # 30 s
    blst_add();  # use default blocklist timeout

2.2.  blst_add_retry_after(min, max)

Adds the source of the current message to the blocklist for the time interval specified in the Retry-After header. If the Retry-After header is missing, it will fail (returns false). If the Retry-After value is less than min, then min seconds will be used instead. If the Retry-After value is greater than max, then max seconds will be used instead.

Example 1.2. blst_add_retry_after usage

# on_reply route
if (msg_status==503){ # blocklist 503 source for Retry-After seconds
    if (! blst_add_retry_after(30, 3600))
        blst_add(60); # if no retry_after header add it for 60s

2.3.  blst_del()

Removes the source of the current message from the blocklist. If the address is not present in the blocklist at the time of the call it returns false.

Example 1.3. blst_del usage


2.4.  blst_is_blocklisted()

Returns true if the source of the current message is blocklisted.

Example 1.4. blst_is_blocklisted usage

    if (blst_is_blocklisted()){
        log("message from a blocklisted source");

2.5.  blst_set_ignore([flags])

Set errors that will not be taken into account when deciding whether to blocklist a destination for the current message or a local reply to the current message.

blst_set_ignore(..) works for forwarding the current message and blst_rpl_set_ignore(...) works for local replies to the current message.

The variants of these functions with no parameters will ignore everything (equivalent to passing 0xff).

The flags are stored internally as a bitmask, and are applied by bitwise ANDing them together. The following flags are available:

  • 0x02 - generic send error (send denied/ failed).
  • 0x04 - connect failed (TCP, TLS or SCTP).
  • 0x08 - ICMP error (not currently used).
  • 0x10 - SIP transaction timeout.
  • 0x20 - 503 reply (stateful mode only). For more details see tmblst_503.


TCP and TLS send and connect errors are handled per connection and not per message. The connection blocklist ignore flags are inherited from the message that caused the connection establishment.

Example 1.5. blst_set_ignore usage

    blst_set_ignore(6); # ignore send and connect errors

2.6.  blst_rpl_set_ignore([flags])

See function blst_set_ignore([flags]).

2.7.  blst_clear_ignore([flags])

Clears blocklist ignore flags previously set by the corresponding blst_set_ignore(...) or blst_rpl_set_ignore(...) functions.

See also blst_set_ignore.

Example 1.6. blst_clear_ignore usage

    blst_clear_ignore(4); # ignore connect errors

2.8.  blst_rpl_clear_ignore([flags])

See function blst_clear_ignore([flags]).