Code Snippets Archives - Philipp's Tech Blog

Dec 17 / 2020
Comments Off on Snippet 0x0F: Recursive search/replace tool “re”

Snippet 0x0F: Recursive search/replace tool “re”

Two and a half years ago, I wrote my first Go program. I wanted to learn another language, and Go looked like a ton of fun: straight forward, easy to learn, and a static binary with no runtime shenanigans. I picked a project and I started hacking. Looking back, the code I wrote is a little cringy, but not terrible. I’d surely do things differently these days, now that I have more Go experience. But we all start somewhere.

However, the tool that I wrote, a recursive search/replace tool which I intelligently dubbed re, is actually incredibly useful: to my own surprise, I use it every day. I haven’t made a single modification to it in all that time (until today for this post). And since I’m in the sharing mood today, I thought I’d share it with the millions of people (cough) that come here every day. Ha!

Aug 06 / 2018
Comments Off on Snippet 0x0E: Booting image files and ISOs with KVM/QEMU (EFI and BIOS)

Code Snippets, Linux, Virtualization

Snippet 0x0E: Booting image files and ISOs with KVM/QEMU (EFI and BIOS)

For my job, I work with file systems and image files a lot: Every day, we mess with Grub, the partition tables (MBR/GPT), EFI and BIOS systems, etc. So pretty much every day, I need to boot some image file or investigate why some image didn’t boot.

This (super duper) short post shows how to boot image files using straight kvm commands.

Dec 04 / 2015
4

Administration, Code Snippets, Linux, Scripting, Security

Snippet 0x0D: Let’s Encrypt – 5 min guide to set up cronjob based certificate renewal

Let’s Encrypt was officially released to the open public today. That means the Internet can finally get free, trusted SSL/TLS certificates. This quick guide shows how to set up Let’s Encrypt with auto-renewal through a cronjob — using the simp_le client, an alternative client developed by one of the same authors who develop the official client.

Aug 22 / 2015
1

Code Snippets, Programming

Snippet 0x0C: Load multiple composer.json files at runtime

Remember the times when we copied PHP “libraries” into our project folder, or we copy and pasted code from some random site into our project? Those times are over. Composer and Packagist are the modern way to manage PHP dependencies. They are great. Almost as good as The Maven repos and their build tools in the Java world. However, while Composer is really good at managing the dependencies of a single project, i.e. one composer.json file, it does not play well if you want to plug different projects together at runtime. And by “does not play well” I mean it simply doesn’t work if you have two or more composer.json files. This quick post demonstrates a way around this limitation. Quick and dirty. Just like the foundations of PHP :-)

Mar 24 / 2015
2

Code Snippets, Linux, Scripting

Snippet 0x0B: Bash completion with sub-commands and dynamic options

Every system administrator, most programmers and countless of command line surfing Linux/Mac users use it every day without thinking twice. Hitting the tab key twice, [TAB][TAB], has become the most common thing in the world. Bash completion is the magic behind the tab key. It’s easy to use, but it’s a pain to write. This tiny post demonstrates how to write scripts for bash completion, with sub-commands and dynamic parameters. A working script is embedded in my open source file sync software Syncany.

Mar 23 / 2015
Comments Off on Snippet 0x0A: Cryptography DOs and DON’Ts

Code Snippets, Security

Snippet 0x0A: Cryptography DOs and DON’Ts

This tiny post is meant as a loose collection of DOs and DON’Ts I’ve come across when I implemented the cryptography concept for Syncany, my open source file sync software. I’m not a cryptography expert, so take my advice with caution — and correct me if you know more than I do.

Jan 24 / 2015
Comments Off on Snippet 0x09: Reading a ZIP/JAR file with PHP (here: a JAR manifest)

Code Snippets, Programming

Snippet 0x09: Reading a ZIP/JAR file with PHP (here: a JAR manifest)

For my open source file sync software Syncany, I have integrated the automatic plugin build process (we provide plugin repository and an easy plugin API to download plugins) with an upload to the Syncany API server. Plugins (JAR files) are uploaded by Travis (example: Samba plugin) to the Syncany server. To serve meta data on through the plugin API, I need to parse the plugins’ MANIFEST.MF files and store them in a database.

This tiny blog post shows you how to read a ZIP/JAR file entry with PHP, and parse JAR manifest (MANIFEST.MF) file. That’s it. Nothing fancy.

Oct 30 / 2014
1

Code Snippets, Programming

Snippet 0x08: HTTP Basic Auth for secure WebSocket connections (with Undertow)

For my open source file sync software Syncany, I use the embedded web server and web socket server Undertow to provide a websocket and REST based interface by the Syncany daemon. Syncany clients (such as the GUI, or potentially a web interface) connect to this daemon, send requests and receive asynchronous events. Syncany’s GUI client also uses the Undertow websocket client to connect to the above mentioned daemon.

To authenticate the websocket client with the daemon, the simple HTTP basic authentication mechanism over HTTPS is used. This tiny post shows you how to authenticate against a websocket server with HTTP basic auth using the Undertow websocket client.

Oct 25 / 2014
Comments Off on Snippet 0x07: Restart Docky from a cronjob (when it crashed)

Code Snippets, Scripting

Snippet 0x07: Restart Docky from a cronjob (when it crashed)

I recently updated from Linux Mint 16 Petra to Linux Mint 17 Qiana. Everything went smoothly, except for my dock Docky. For some reason, Docky decides to crash every once in a while with some error message.

Instead of fixing this error or reporting it, I decided to find the easy way out and simple set up a cronjob to restart Docky every minute (if it has crashed).

Oct 17 / 2014
Comments Off on Snippet 0x06: Disable SSLv3 in Firefox to protect against POODLE attack

Code Snippets, Security

Snippet 0x06: Disable SSLv3 in Firefox to protect against POODLE attack

The recent POODLE attack (Padding Oracle On Downgraded Legacy Encryption) exploits a vulnerability of an older version of SSL (SSLv3) by performing a padding oracle attack — and thereby allowing a man-in-the-middle scenario.

To be vulnerable, both client (browser) and server have to support SSLv3. If either one does not support or has disabled the protocol, this vulnerability cannot be exploited. This tiny article shows you how to disable SSLv3 in Firefox — thereby effectively making your browser POODLE-safe.

Posts Categorized / Code Snippets

Snippet 0x0F: Recursive search/replace tool “re”

Snippet 0x0E: Booting image files and ISOs with KVM/QEMU (EFI and BIOS)

Snippet 0x0D: Let’s Encrypt – 5 min guide to set up cronjob based certificate renewal

Snippet 0x0C: Load multiple composer.json files at runtime

Snippet 0x0B: Bash completion with sub-commands and dynamic options

Snippet 0x0A: Cryptography DOs and DON’Ts

Snippet 0x09: Reading a ZIP/JAR file with PHP (here: a JAR manifest)

Snippet 0x08: HTTP Basic Auth for secure WebSocket connections (with Undertow)

Snippet 0x07: Restart Docky from a cronjob (when it crashed)

Snippet 0x06: Disable SSLv3 in Firefox to protect against POODLE attack

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