CPP_HTTP_Client

This is a side project for me to gain a deeper understanding of low-level networking concepts as well as the HTTP spec.

Note This library only works on Linux and macOS!

Dependencies

• openssl development library
• C++20
• cmake 3.23.2 (for integrating this library into your project)
• spdlog for logging (can be bundled automatically by CMake)

Features ✨

• GET/POST/PUT/DELETE requests for HTTP and HTTPS connections
• Redirect handling (for 3XX codes)
• Configure requests with ease
• Configurable logging of low-level details

Hello World Example

#include <HttpClient.hpp>
#include <iostream>

int main() {
  HttpClient client{"https://jsonplaceholder.typicode.com"};
  auto res = client.get("/todos/1");
  std::cout << res.body << '\n';
}

Design

Instead of making requests with a single url i.e.

client.get("https://jsonplaceholder.typicode.com/todos/1");

The base url is first set, and then requests are made using the uri. The base_url consists of the scheme e.g. https or http and the host name e.g. jsonplaceholder.typicode.com i.e.

HttpClient client{"https://jsonplaceholder.typicode.com"};
client.get("/todos/1");

It is designed this way so that each client is bound to a single TCP connection which can be re-used for multiple requests to the same domain.

Installation

CMake Integration

This project should be used through its CMake integration.
Simply add the following lines to your project CMakeLists.txt file:

include(FetchContent)

cmake_minimum_required(VERSION 3.23.2)

project(<Your Project Name> CXX)

FetchContent_Declare(
  HttpClient
  GIT_REPOSITORY https://github.com/WilsonOh/CPP_HTTP_Client.git
  GIT_TAG main
)

FetchContent_MakeAvailable(HttpClient)

add_executable(${PROJECT_NAME} <Your Source Files>...)

target_link_libraries(${PROJECT_NAME} PRIVATE HttpClient)

The manual way

You can also git clone this repo and simply include all the source files under src/ for complilation

More examples

Configuring the logging level of a HttpClient instance

By default, each HttpClient instance has its logging level set to spdlog::level::off, thus silencing all logs.

#include <HttpClient.hpp>
#include <iostream>

int main() {
  // Set logging level of this client to `debug`
  HttpClient client("https://jsonplaceholder.typicode.com",
                    spdlog::level::debug);
  auto res = client.post("/posts", R"({
    title: 'foo',
    body: 'bar',
    userId: 1,
  })");
  std::cout << res.body << '\n';
}

The logs provide an easy way for users to debug a failed HTTP request for example. At the debug logging level, things like the IP address of the domain connected, the raw HTTP request being sent to the server, the raw HTTP response headers recieved from the server will be logged out!

Checking the response

#include <HttpClient.hpp>
#include <iostream>

int main() {
  HttpClient client{"https://jsonplaceholder.typicode.com"};
  auto res = client.get("/todos/1");
  if (res.statuscode != 200) {
    ...
  }
  if (res.headers["Content-Type"] != "application/json") {
    ...
  }
  std::cout << res.body << '\n';
}

Adding headers

#include "HttpClient.hpp"
#include <iostream>

int main() {
  HttpClient client{"https://jsonplaceholder.typicode.com"};
  auto res = client.get("/todos/1", {{"Accept", "application/json"}});
  std::cout << res.body << '\n';
}

Sending a request body

#include "HttpClient.hpp"
#include <iostream>

int main() {
  HttpClient client{"https://jsonplaceholder.typicode.com"};
  auto res = client.post("/posts", R"({
    title: 'foo',
    body: 'bar',
    userId: 1,
  })");
  std::cout << res.body << '\n';
}

Sending a request body with headers

#include "HttpClient.hpp"
#include <iostream>

int main() {
  HttpClient client{"https://jsonplaceholder.typicode.com"};
  auto res = client.post("/posts", R"({
    title: 'foo',
    body: 'bar',
    userId: 1,
  })",
  {{"Content-type", "application/json; charset=UTF-8"}}
  );
  std::cout << res.body << '\n';
}