dnsmasq packaged for the Zig build system

This is dnsmasq, a lightweight DNS forwarder, DHCP, TFTP and router advertisement server, packaged for Zig. It builds the dnsmasq executable from the upstream release, so that it can be cross-compiled and used from other Zig projects, for example to run it in their tests.

Status

Architecture \ OS	Linux	macOS	FreeBSD	NetBSD	OpenBSD
x86_64	✅	?	✅	✅	✅
arm 64	✅	✅	✅	✅	✅

Also builds for Linux on arm, x86, riscv64, powerpc64le, s390x and loongarch64, with both glibc and musl.

Refname	dnsmasq version	Zig 0.18-dev	Zig 0.17.x	Zig 0.16.x
master, 2.93	v2.93	✅	✅	✅

Install

Clone this repository, and install to a prefix of your choice, for example ~/.local:

zig build -p ~/.local -Doptimize=ReleaseSafe -Dstrip=true

This installs dnsmasq in ~/.local/bin, and its manual page in ~/.local/share/man/man8. The prefix defaults to zig-out. Zig downloads the dnsmasq sources itself: there is nothing else to install.

To build for another machine, add -Dtarget and copy the prefix over, for example -Dtarget=aarch64-linux-musl for a statically linked executable that runs on any 64-bit ARM Linux. Zig can only target macOS from a Mac, and only for the Mac itself: see Limitations.

Options are given the same way, for example -Dtftp=false to leave the TFTP server out: see Options.

Use as a dependency

Add the dependency to your build.zig.zon by running the following command:

zig fetch --save git+https://github.com/allyourcodebase/dnsmasq#master

Then, from your build.zig, get the executable to install it, or to run it:

const dnsmasq = b.dependency("dnsmasq", .{
    .target = target,
    .optimize = optimize,
});

b.installArtifact(dnsmasq.artifact("dnsmasq"));

const run = b.addRunArtifact(dnsmasq.artifact("dnsmasq"));
run.addArgs(&.{ "--keep-in-foreground", "--port=5353" });

zig build test runs smoke tests: the version it reports, and that it accepts both upstream's example configuration and one using the enabled features.

Options

  -Dstrip=[bool]               Omit debug information
  -Dpic=[bool]                 Produce Position Independent Code. Defaults to the target's default
  -Dbroken_rtc=[bool]          For systems without a real-time clock keeping time across reboots: use uptime, and store lease lengths instead of expiry times. Defaults to false
  -Ddhcp=[bool]                Enable the DHCPv4 server (disabling it also disables DHCPv6). Defaults to true
  -Ddhcp6=[bool]               Enable the DHCPv6 server and router advertisements. Defaults to true
  -Dtftp=[bool]                Enable the TFTP server. Defaults to true
  -Dscript=[bool]              Enable calling a script on DHCP lease changes. Defaults to true
  -Dauth=[bool]                Enable the authoritative DNS mode. Defaults to true
  -Dipset=[bool]               Enable adding resolved addresses to ipsets (Linux and BSD only). Defaults to true
  -Dloop=[bool]                Enable forwarding loop detection. Defaults to true
  -Ddumpfile=[bool]            Enable dumping packets to a pcap file. Defaults to true
  -Dinotify=[bool]             Enable watching configuration files with inotify (Linux and FreeBSD 15 or later only). Defaults to true
  -Did=[bool]                  Enable answering the id.server, version.bind, etc. CHAOS queries. Defaults to true

These map to the NO_* compile-time options of upstream's config.h, and the defaults are upstream's.

Limitations

Optional dependencies

The features of dnsmasq which need an external library are not built: DNSSEC (nettle), D-Bus, ubus, IDN and IDN2, Lua scripts, conntrack and nftables sets. Translations are not built either.

macOS

Zig's bundled copy of the macOS headers lacks some networking ones dnsmasq needs (netinet/ip6.h), so the build relies on the Xcode SDK, which Zig only finds when building for the host. Build without -Dtarget, or with only -Dcpu, -Doptimize, etc. Explicitly targeting macOS, including from an Intel Mac for an ARM one, or cross-compiling to it from another OS, fails to compile.

Undefined behavior

Upstream relies on undefined behavior (misaligned accesses, for one), which Zig's default sanitizer for C turns into a crash in Debug and ReleaseSafe builds. It is disabled for dnsmasq's sources, as it is in upstream's own build.

Other operating systems

Zig cannot provide a libc for DragonFly BSD or illumos, so they are not supported, nor are Windows and WASI, which dnsmasq does not support.

License

The build scripts are MIT licensed. dnsmasq itself is licensed under the GPL, version 2 or 3: see its COPYING.