iwscan-xml — wireless network scanner with XML-formatted output

This repository contatins the results of the work I did in 2016 and which was mostly finished. So it may be usable... or may be not, depending of what you need.

Problem

Main goal of this project is to implement scanning for wireless networks with machine-readable output format, primarily for use in Python scripts. Solutions which parses iwlist scan output directly are not robust enough, because such output primarily designed to be human-readable, and may be hard for a correct and reliable machine parsing.

So it has been decided to modify iwlist scan source code to fit our purposes.

Why not JSON?

• Main reason not to use JSON is its design limitation: it doesn't allow to place multiple elements with identical names in the same object. This is a serious problem due to implementation specific of iwlist scan: it gets scan results from kernel via socket and parses it with state machine. So, if one of the data blocks ("events") contains e.g. list of frequencies, we cannot know whether the next block will contain a continuation of this list, or some other data. The most robust way is to close list after reaching end of data block, but it may leads to the appearance of several lists with the same name, containing fragments of one whole. This is not the problem for XML/XPath, but is a big problem for JSON.
• Second reason is possibility to easy transform XML with XSLT, e.g. to merge sets of "same" elements noted above into single ones (see ./stuff/iwscan-group-same.xslt).
• Another reason is the existence of XPath query language, which allows to easily search and extract various data from parsed XML tree (for very simple example see ./stuff/iwscan.py).
• And some minor issues which mostly fixed in JSON5 (e.g. trailing commas) which however can bring a lot of pain with some "modern" JSON parsers.

TL;DR: JSON is great, but inappropriate for this particular task.

How it works?

• iwscan is a simple console tool that works like iwlist scan excepting for output format (XML). See ./man/iwscan.{1,html} for details.
• iwscand uses the same code (iwscanlib.c -> libiwscan.so.0.1), but works in a different manner: it starts as a daemon and waits for SIGUSR1. After receiving this signal, it performs a scan and dumps results to the given file (which can be ordinary file or FIFO). If you want to stop it, use SIGTERM. See ./man/iwscand.{1,html} for details.

Format

XML format of the scan results is described in man/iwscan-xml-format.{7,html}.

Also note that formatting must match to the scheme given in ./stuff/iwscan.xsd and can be validated using xmllint.

Installing

See ./INSTALL.md.

Licensing

Since this work is derivative from wireless-tools which licensed under GPLv2, iwscan-xml also licensed under the same license.

But there are modern tools like "iw"!

Yes. But this project uses obsolete wireless-tools as a base. This is a "fait accompli". Simply, do not use iwscan-xml if it doesn't fits your problem.

Current status

Work was finished in the beginning of 2016, and I didn't touch the code since that time. If you want to modify the code for your goal, do not consider yourself obliged to send me a pull requests, since I have not been working on this project for a long time... Excepting for fixing bugs and vulnerabilities, because it definitely deserve attention.