hooktftp

Hooktftp is a dynamic read-only TFTP server. It's dynamic in a sense it is executes hooks matched on read requests (RRQ) instead of reading files from the file system. Hooks are matched with regular expressions and on match hooktftp will execute a script, issue a HTTP GET request or just reads the file from the filesystem.

This is inspired by puavo-tftp. It's written in Go in the hope of being faster and more stable.

Usage

hooktftp [-v] [config]

Config will be read from /etc/hooktftp.yml by default. Verbose option -v print log to stderr insteadof syslog.

Configuration

Configuration file is in yaml format and it can contain following keys:

• port: Port to listen (required)
• user: User to drop privileges to
• hooks: Array of hooks. One or more is required

Hooks

Hooks consists of following keys:

• type: Type of the hook
  • file: Get response from the file system
  • http: Get response from a HTTP server
  • shell: Get response from external application
• regexp: Regexp matcher
  • Hook is executed when this regexp matches the requested path
• template: A template where the regexp is expanded

Regexp can be expanded to the template using the $0, $1, $2 etc. variables. $0 is the full matched regexp and rest are the matched regexp groups.

Example

To share files from /var/lib/tftpboot add following hook:

type: file
regexp: ^.*$
template: /var/lib/tftpboot/$0

Share custom boot configurations for PXELINUX from a custom http server:

type: http
regexp: pxelinux.cfg\/01-(([0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2})
template: http://localhost:8080/boot/$1

The order of the hooks matter. The first one matched is used.

To put it all together:

port: 69
user: hooktftp
hooks:
  - type: http
    regexp: pxelinux.cfg\/01-(([0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2})
    template: http://localhost:8080/boot/$1

  - type: file
    regexp: ^.*$
    template: /var/lib/tftpboot/$0

Install

Compiling from sources

Install Go, make sure you have git and bazaar too. Assuming you've successfully set up GOPATH and have GOPATH/bin on your path, simply:

$ make build

Now you should have a standalone hooktftp binary on your path.

$ hooktftp -h
Usage: hooktftp [-v] [config]

You can use gox to create Darwin and Linux executables:

$ brew install gox
$ make gox
$ tree
bin
├── darwin_amd64
│   └── hooktftp
└── linux_amd64
    └── hooktftp

2 directories, 2 files

Docker

Try hooktftp by using the official Docker image:

$> docker pull tftpgoteam/hooktftp
$> docker run --rm -ti -v /tmp/myfiles:/var/lib/tftpboot tftpgoteam/hooktftp

Build Debian package

The package has been created with devscripts and dh-make. To build it:

debuild -e GOPATH=$PWD -us -uc

History

Please read debian changelog file.

Tests

You can start unit and end-to-end test with Makefile target test:

make test

Hack with Docker

The easiest way to start hacking with hooktftp is to use Docker.

# Clone the repository
[host]> git clone git@github.com:tftp-go-team/hooktftp.git
[host]> cd hooktftp

# Create the configuration file. Edit this file later to change hooktftp configuration.
[host]> touch /tmp/hooktftp.yml

# Run the official golang image
[host]> docker run --rm -ti \
    --name tftp-server \
    -v /tmp/hooktftp.yml:/etc/hooktftp.yml:ro \
    -v `pwd`:/go/src/github.com/tftp-go-team/hooktftp \
    golang

# From the container, run hooktftp
[container]> cd src/github.com/tftp-go-team/hooktftp/
[container]> make
[container]> ./src/hooktftp -v

# To query the TFTP server, run the client on another container
[host]> docker run --rm -ti --link tftp-server ubuntu bash
[container]> apt-get update && apt-get install -y tftp-hpa
[container]> echo binary $'\n' get myfile | tftp tftp-server