cHTTP

cHTTP is an HTTP client and server library for C with minimal dependencies and distributed as a single chttp.c file.

Here is a list of features:

HTTP 1.1 client and server
Fully non-blocking
Cross-Platform (Windows & Linux)
HTTPS support (using OpenSSL)
Virtual Hosts
Single-threaded
Zero-copy interface

Getting Started

The library is distributed as a single amalgamated chttp.c file or as a static library, so you can:

Download chttp.c and chttp.h from the repository (no need to clone the project) and include them in your soource tree
or clone the project and build the static library by running:

make libchttp.a

If you used the amalgamated files, these are the flags required to build a project:

# Linux
gcc your_app.c chttp.c

# Windows
gcc your_app.c chttp.c -lws2_32

If you are using the static library, instead of adding chttp.c, you will need to add the -lchttp flag.

By default, the library is built without HTTPS. To enable it, add the flags -DHTTPS_ENABLED -lssl -lcrypto.

# Linux + HTTPS
gcc your_app.c chttp.c -DHTTPS_ENABLED -lssl -lcrypto

# Windows + HTTPS
gcc your_app.c chttp.c -lws2_32 -DHTTPS_ENABLED -lssl -lcrypto

Example

To give you a feel of the library, here are some examples of programs using cHTTP. To learn more, you can look at the files in examples/ (they are intended to be skimmed in order).

Here is a client performing a GET request:

#include <stdio.h>
#include <chttp.h>

int main(void)
{
    http_global_init();

    HTTP_String url = HTTP_STR("http://example.com/index.html");

    HTTP_String headers[] = {
        HTTP_STR("User-Agent: cHTTP"),
    };

    HTTP_Response *res = http_get(url, headers, 1);

    fwrite(res->body.ptr, 1, res->body.len, stdout);

    http_response_free(res);
    http_global_free();
    return 0;
}

And this is a server:

#include <chttp.h>

int main(void)
{
    http_global_init();
    HTTP_Server *server = http_server_init(HTTP_STR("127.0.0.1"), 8080);

    for (;;) {

        HTTP_Request *req;
        HTTP_ResponseBuilder builder;
        http_server_wait(server, &req, &builder);

        http_response_builder_status(builder, 200);
        http_response_builder_header(builder, "Content-Type: text/plain");
        http_response_builder_body(builder, HTTP_STR("Hello, world!"));
        http_response_builder_done(builder);
    }

    http_server_free(server);
    http_global_free();
    return 0;
}

Platform Support

cHTTP officially supports Linux and Windows.

HTTPS support

Currently, HTTPS is implemented using OpenSSL. If you are on Windows, you'll need to install it manually.

Scalability

cHTTP is designed to reach moderate scale to allow a compact and easy to work with implementation. The non-blocking I/O is based on poll() which I would say works up to about 500 concurrent connections. If you have more than that, you should consider APIs like epoll, io_uring, and I/O completion ports. If you do go that route, you can still reuse the cHTTP I/O independent core (see HTTP_Engine) to handle the HTTP protocol for you, both for client and server.

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