Nginx udplog module

This module provides simple UDP logging of incoming HTTP requests' uris (ngx_http_request_t.uri) and their CRC-32 checksums for nginx web server.

Tested with mainline nginx version 1.11.5.

Description

Packets are sent over UDP during log phase (NGX_HTTP_LOG_PHASE) since it's made specially for such kind of things. There is one memory allocation per incoming request to include uri's CRC-32 checksum. It possibly can be avoided at the cost of destructive changes of uri's data field. To achieve this we need to write extra 4 bytes for CRC-32, so uri itself can be compressed somehow to become 4 bytes less, but it barely works for short uris (e.g. uri / is 1 byte long). Another possible approach is to preallocate enough buffers and use them to serve requests.

Configuration directives

syntax: udplog <hostname> <port>

context: main

Example configuration

http {

    [...]
    
    udplog 127.0.0.1 9999;

    server {
        [...]
    }
}

Testing

This module can be tested in two ways: with netcat utility or with server.py.

netcat

To test module locally, use:

$ netcat -ul PORT

e.g. $ netcat -ul 9999 to listen on localhost

server.py

This is a python3 script, adjust HOST and PORT variables in it and you are ready to go. Defaults are localhost and port 9999.