DNS Client Application
======================

The DNS resolver or DNS client application demonstrates how to use the
DNS resolver API.

The DNS API allows to recover IPv4 and IPv6 addresses.


API Return Codes
================

API return codes are documented in the API (see include/iot/dns_client.h).

Macro	|   Value   |	Description
------------------------------------------------------------------------
O			is always success
-EINVAL	    -22		if an invalid parameter was detected
-EIO	    -5		network error
-ENOMEM	    -12		memory error, perhaps related to network buffers


Requirements
============

'net_tools':

    https://wiki.zephyrproject.org/view/Networking-with-Qemu

'dnsmasq' application. The dnsmasq version used in this sample is:

    dnsmasq -v
    Dnsmasq version 2.76  Copyright (c) 2000-2016 Simon Kelley


Building Instructions
=====================

Read src/config.h, change the IP addresses according to the LAN
environment.

In a terminal window, type make pristine && make to build this sample.


Usage
=====

Run 'loop_socat.sh' and 'loop-slip-tap.sh' as indicated at:

    https://gerrit.zephyrproject.org/r/gitweb?p=net-tools.git;a=blob;f=README

Set the IPv4 ip address:

    ip addr add 192.0.2.2/24 dev tap0

Open a terminal window and type:

    dnsmasq -i tap0 -p 5353 -d

NOTE: some systems may require root privileges to run dnsmaq, use sudo or su.

If dnsmasq fails to start with an error like this:

    dnsmasq: failed to create listening socket for port 5353: Address already in use

open a terminal window and type:

    killall -s KILL dnsmasq

For QEMU, type:

    make qemu


Sample Output (CONFIG_NET_IPV6=n, CONFIG_NET_IPV4=y)
====================================================

To exit from QEMU enter: 'CTRL+a, x'
[QEMU] CPU: qemu32

-------------------------------------------
[run_dns:127] name: not_a_real_domain_name
rc: -22

-------------------------------------------
[run_dns:127] name: zephyrproject.org
[run_dns:151] 140.211.169.8

-------------------------------------------
[run_dns:127] name: www.zephyrproject.org
[run_dns:151] 140.211.169.8

-------------------------------------------
[run_dns:127] name: gerrit.zephyrproject.org
[run_dns:151] 199.19.213.246

-------------------------------------------
[run_dns:127] name: jira.zephyrproject.org
[run_dns:151] 199.19.213.246

-------------------------------------------
[run_dns:127] name: jenkins.zephyrproject.org
[run_dns:151] 199.19.213.246

-------------------------------------------
[run_dns:127] name: linuxfoundation.org
rc: -5

-------------------------------------------
[run_dns:127] name: www.linuxfoundation.org
[run_dns:151] 140.211.169.4

-------------------------------------------
[run_dns:127] name: collabprojects.linuxfoundation.org
[run_dns:151] 140.211.169.4

-------------------------------------------
[run_dns:127] name: events.linuxfoundation.org
[run_dns:151] 140.211.169.4

-------------------------------------------
[run_dns:127] name: training.linuxfoundation.org
[run_dns:151] 140.211.169.4

Bye!

Known Issues
============

The above sample contains a rc: -22 (-EINVAL). This is the expected behavior
for that domain name.