cHTTP

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

Features & Limitations

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

Example

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 which comes preinstalled on Linux but not Windows. It must be enabled by passing the -DHTTPS_ENABLED flag to gcc when building.

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 independant core (see HTTP_Engine) to handle the HTTP protocol for you, both for client and server.

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