serval-dna/doc/Development.md

Notes for Serval DNA Developers

Serval Project, September 2016

Introduction

This document is intended for all developers of Serval DNA, and also for non-developers who are experiencing errors in the build process.

Autoconf

The configure.ac file is an autoconf script that contains instructions for adapting the build of Serval DNA to different platforms and CPU architectures. This script makes use of many GNU M4 macros, each of which tests an aspect of the build environment, such as the make and version of the C compiler (eg, GCC, Clang), the availability of headers, functions and system calls in the standard library, and so forth.

Most of these M4 macros are standard, either supplied with autoconf or from the autoconf macro archive. Some macros are specific to Serval DNA, either to improve on a standard macro or perform a test for which no standard macro exists. These extra macros are locally defined in files within the m4 sub-directory.

The autoreconf command used in the build instructions generates an aclocal.m4 file that includes all the necessary files from the m4 directory. In turn, it then includes this aclocal.m4 file when invoking GNU M4 to convert the configure.ac file into the ./configure script.

Internally, autoconf generates the aclocal.m4 file by invoking the aclocal utility. Used without arguments, aclocal may emit some warning messages that look like this:

$ cd serval-dna
$ aclocal
configure.ac:18: warning: Unsupported attribute section, the test may fail
../../lib/autoconf/lang.m4:224: AC_LANG_SOURCE is expanded from...
../../lib/autoconf/lang.m4:241: AC_LANG_PROGRAM is expanded from...
../../lib/autoconf/lang.m4:193: AC_LANG_CONFTEST is expanded from...
../../lib/autoconf/general.m4:2672: _AC_LINK_IFELSE is expanded from...
../../lib/autoconf/general.m4:2689: AC_LINK_IFELSE is expanded from...
../../lib/m4sugar/m4sh.m4:639: AS_IF is expanded from...
../../lib/autoconf/general.m4:2042: AC_CACHE_VAL is expanded from...
../../lib/autoconf/general.m4:2063: AC_CACHE_CHECK is expanded from...
/usr/share/aclocal/ax_gcc_var_attribute.m4:57: AX_GCC_VAR_ATTRIBUTE is expanded from...
configure.ac:18: the top level
$

These messages are harmless; the correct aclocal.m4 is still generated. To suppress most of these messages from the output of aclocal and autoreconf, give the -I m4 option:

$ cd serval-dna
$ autoreconf -f -i -I m4
$

libsodium

Libsodium is the cryptographic library that Serval DNA uses for all its encryption, authentication and secure hashing.

libsodium is a portable, cross-compilable fork of NaCl, with a compatible API. The design choices in NaCl-libsodium, particularly in regard to the Curve25519 Diffie-Hellman function, emphasise security, and the “magic constants" in NaCl-libsodium have clear rationales. By contrast, the NIST standard curves emphasise “performance" at the cost of security and do not describe the specific origins of certain constants. Despite the emphasis on higher security, NaCl-libsodium primitives are faster across-the-board than most implementations of the NIST standards.

• In order to build Serval DNA, the libsodium development files must be available, such as the source header file <sodium.h> and the static library libsodium.a.

• In order to run Serval DNA, the libsodium run-time files must be available, such as the dynamic library libsodium.so.

libsodium-dev

On systems that provide a libsodium development package, simply install that package. For example, on Debian and Ubuntu:

$ sudo apt-get install libsodium-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  libsodium-dev
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Selecting previously unselected package libsodium-dev:amd64.
(Reading database ... 223406 files and directories currently installed.)
Preparing to unpack .../libsodium-dev_1.0.11-1_amd64.deb ...
Unpacking libsodium-dev:amd64 (1.0.11-1) ...
Setting up libsodium-dev:amd64 (1.0.11-1) ...
$

build-libsodium.sh

On systems that do not provide a libsodium development package (even though they may provide a run-time package), such as Mac OS X, the libsodium development files can be locally installed by downloading the libsodium source code and building it. The build-libsodium.sh script will do this:

$ ./build-libsodium.sh
...
The libsodium run-time and development files have been installed in:
/absolute/path/name/serval-dna/libsodium

To use this installation of libsodium, set up the environment using the
shell's "dot" command to source its settings.sh script, for example:

   . libsodium/settings.sh ; ./configure

$

In the event of failure, check that:

• the github.com web site can be reached
• there is at least 60 MB of available disk space
• there is no other libsodium development package already installed

For more information, refer to the libsodium installation documentation and the script's help message:

$ ./build-libsodium.sh --help
...
$

Debian/Ubuntu

A single apt-get command will install all mandatory and testing dependencies before building on Debian and Ubuntu systems:

$ sudo apt-get --yes install libc6-dev libsodium-dev jq curl
Reading package lists... Done
Building dependency tree
Reading state information... Done
libc6-dev is already the newest version (2.23-5).
The following NEW packages will be installed:
  curl jq libsodium-dev
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 544 kB of archives.
After this operation, 1,683 kB of additional disk space will be used.
Get:1 http://ftp.us.debian.org/debian testing/main amd64 curl amd64 7.50.1-1 [218 kB]
Get:2 http://ftp.us.debian.org/debian testing/main amd64 jq amd64 1.5+dfsg-1 [156 kB]
Get:3 http://ftp.us.debian.org/debian testing/main amd64 libsodium-dev amd64 1.0.11-1 [170 kB]
Fetched 544 kB in 1s (304 kB/s)
Selecting previously unselected package curl.
(Reading database ... 205089 files and directories currently installed.)
Preparing to unpack .../0-curl_7.50.1-1_amd64.deb ...
Unpacking curl (7.50.1-1) ...
Selecting previously unselected package jq.
Preparing to unpack .../1-jq_1.5+dfsg-1_amd64.deb ...
Unpacking jq (1.5+dfsg-1) ...
Selecting previously unselected package libsodium-dev:amd64.
Preparing to unpack .../2-libsodium-dev_1.0.11-1_amd64.deb ...
Unpacking libsodium-dev:amd64 (1.0.11-1) ...
Setting up jq (1.5+dfsg-1) ...
Setting up curl (7.50.1-1) ...
Setting up libsodium-dev:amd64 (1.0.11-1) ...
Processing triggers for man-db (2.7.5-1) ...
$

Apple Mac OS X

libsodium for OS X

Although the libsodium package is available for Mac OS X using the homebrew package manager, that package only provides the run-time library, not the development files; for example, it does not provide the #include <sodium.h> header.

The libsodium development files can be installed locally on Mac OS X using the build-libsodium.sh script.

Test utilities

The OS X grep(1) , OS X sed(1) and OS X awk(1) tools provided by Apple Mac OS X are the BSD variants. The test scripts require the GNU variants with the names ggrep, gsed and gawk, which can be installed on Mac OS X using the homebrew package manager:

$ brew tap homebrew/dupes
==> Tapping homebrew/dupes
Cloning into '/usr/local/Library/Taps/homebrew/homebrew-dupes'...
remote: Counting objects: 42, done.
remote: Compressing objects: 100% (42/42), done.
remote: Total 42 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (42/42), done.
Checking connectivity... done.
Tapped 38 formulae (103 files, 120.0K)

$ brew install grep
==> Installing grep from homebrew/dupes
==> Installing dependencies for homebrew/dupes/grep: pcre
==> Installing homebrew/dupes/grep dependency: pcre
==> Downloading https://homebrew.bintray.com/bottles/pcre-8.38.el_capitan.bottle.tar.gz
==> Pouring pcre-8.38.el_capitan.bottle.tar.gz
/usr/local/Cellar/pcre/8.38: 146 files, 5.4M
==> Installing homebrew/dupes/grep
==> Downloading https://homebrew.bintray.com/bottles-dupes/grep-2.22.el_capitan.bottle.tar.gz
==> Pouring grep-2.22.el_capitan.bottle.tar.gz
==> Caveats
The command has been installed with the prefix "g".
If you do not want the prefix, install using the "with-default-names" option.
==> Summary
/usr/local/Cellar/grep/2.22: 14 files, 756.5K

$ brew install gnu-sed
==> Downloading https://homebrew.bintray.com/bottles/gnu-sed-4.2.2.el_capitan.bottle.2.tar.gz
==> Pouring gnu-sed-4.2.2.el_capitan.bottle.2.tar.gz
tar: Failed to set default locale
==> Caveats
The command has been installed with the prefix "g".
If you do not want the prefix, install using the "with-default-names" option.
If you need to use these commands with their normal names, you
can add a "gnubin" directory to your PATH from your bashrc like:
PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"
Additionally, you can access their man pages with normal names if you add
the "gnuman" directory to your MANPATH from your bashrc as well:
MANPATH="/usr/local/opt/gnu-sed/libexec/gnuman:$MANPATH"
==> Summary
/usr/local/Cellar/gnu-sed/4.2.2: 9 files, 452K

$ brew install gawk
==> Downloading https://homebrew.bintray.com/bottles/gawk-4.1.3.el_capitan.bottle.tar.gz
==> Pouring gawk-4.1.3.el_capitan.bottle.tar.gz
/usr/local/Cellar/gawk/4.1.3: 63 files, 3.2M

$

The jq(1) tool is not provided by Apple Mac OS X, so it must be installed using the homebrew package manager:

$ brew install jq
==> Installing dependencies for jq: oniguruma
==> Installing jq dependency: oniguruma
==> Downloading https://homebrew.bintray.com/bottles/oniguruma-6.1.1.el_capitan.bottle.tag.gz
==> Pouring oniguruma-6.1.1.el_capitan.bottle.tag.gz
/usr/local/Cellar/oniguruma/6.1.1: 16 files, 1.3M
==> Installing jq
==> Downloading https://homebrew.bintray.com/bottles/jq-1.5_2.el_capitan.bottle.tag.gz
==> Pouring jq-1.5_2.el_capitan.bottle.tag.gz
/usr/local/Cellar/jq/1.5_2: 18 files, 958K
$

About the examples

The examples in this document are Bourne shell commands, using standard quoting and variable expansion. Commands issued by the user are prefixed with the shell prompt $ to distinguish them from the output of the command. Single and double quotes around arguments are part of the shell syntax, so are not seen by the command. Lines ending in backslash \ continue the command on the next line.

The directory paths used in the examples are for illustrative purposes only, and may need to be changed for your particular circumstances.

---

Copyright 2015 Serval Project Inc.
Copyright 2016 Flinders University
Available under the Creative Commons Attribution 4.0 International licence.