Socket HTTP GET Example

Overview

The sockets/http_get sample application for Zephyr implements a simple HTTP GET client using a BSD Sockets compatible API. The purpose of this sample is to show how it’s possible to develop a sockets application portable to both POSIX and Zephyr. As such, it is kept minimal and supports only IPv4.

The source code for this sample application can be found at: samples/net/sockets/http_get.

Requirements

  • Networking with the host system
  • or, a board with hardware networking
  • NAT/routing should be set up to allow connections to the Internet
  • DNS server should be available on the host to resolve domain names

Building and Running

Build the Zephyr version of the application like this:

west build -b <board_to_use> samples/net/sockets/http_get

board_to_use defaults to qemu_x86. In this case, you can run the application in QEMU using make run. If you used another BOARD, you will need to consult its documentation for application deployment instructions. You can read about Zephyr support for specific boards in the documentation at Supported Boards.

After the sample starts, it issues HTTP GET request to “google.com:80” and dumps the response. You can edit the source code to issue a request to any other site on the Internet (or on the local network, in which case no NAT/routing setup is needed). Exit QEMU by pressing CTRL+A x.

Enabling TLS support

Enable TLS support in the sample by building the project with the overlay-tls.conf overlay file enabled, for example, using these commands:

west build -b qemu_x86 samples/net/sockets/http_get -- -DCONF_FILE="prj.conf overlay-tls.conf"

An alternative way is to specify -DOVERLAY_CONFIG=overlay-tls.conf when running west build or cmake.

The certificate used by the sample can be found in the sample’s src directory. The certificate was selected to enable access to the default website configured in the sample (https://google.com). To access a different web page over TLS, provide an appropriate certificate to authenticate to that web server.

Note, that TLS support in the sample depends on non-posix, TLS socket functionality. Therefore, it is only possible to run TLS in this sample on Zephyr.

Running application on POSIX Host

The same application source code can be built for a POSIX system, e.g. Linux. (Note: if you look at the source, you will see that the code is the same except the header files are different for Zephyr vs POSIX.)

To build for a host POSIX OS:

$ make -f Makefile.posix

To run:

$ ./http_get

As can be seen, the behavior of the application is the same as the Zephyr version.