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chttp is a simple HTTP server library developed in C. It allows for simple request routing.

It is currently being developed and tested on MacOS and FreeBSD.


#include <chttp/CHTTP.c>

// Handler for '/' returns the client's user agent.
Result indexHandler(Request req, Response res) {
  Header_set(&res->headers, "Content-type", "text/html");

  char *ua = Header_get(&req->headers, "User-agent");
  Response_printf(res, "Your user-agent is: <b>%s</b>", ua);

  return ResultOK(NULL)

// Handler for Error 404
Result errorHandler404(Request req, Response res) {
  Header_set(&res->headers, "Content-type", "text/html");
  Response_printf(res, "<h1>Error 404</h1><b>Route Not Found</b>");
  return ResultOK(NULL);

int main () {
  // Create a server.
  Server server = Server_new();

  // Set up a route.
  Server_route(server, "/", indexHandler);
  // Set up Error 404 Handler
  Server_route404(server, errorHandler404);

  // Try to listen on port 8080, or handle the error if one occurs.
  // The first argument to OkOr is the result type on success - Server_listen
  // doesn't return anything meaningful, so we set it to void*.
  OkOr(void*, (Server_listen(server, 8080)), {
      fprintf(stderr, "Error in Server_listen: %s\n", OkOrMessage);


chttp can be included with:

#include <chttp/CHTTP.c>

chttp operates through a Server object, which is used to configure the server:

Server server = Server_new();

Result Type

chttp communicates error states through a special type, Result. A Result contains either a value pointer, when successful, or an error string, when failing. The value pointer can be NULL when no real result value is needed.

Checking for errors can be done with the OkOr macro, which is used as follows:

OkOr(Result Type, (Statement), { Error Handler });

If the result of Statement is successful, the result value will be cast to Result Type and made available as the value of the statement.

If the result is a failure, the code within Error Handler will be run. Within this block, the macro OkOrMessage refers to the error message, as a char*, and the macro OkOrResult refers to the entire result object.

A success result can be created using ResultOK(value), and an error result can be created with ResultError("message").

Starting the Server

To start the server, execute Server_listen(server, port). This returns a Result<void>, which can be handled like so:

OkOr(void*, (Server_listen(server, 8080)), {
    fprintf(stderr, "%s\n", OkOrMessage);
    return 1;

The server will run until interrupted with SIGINT, or with Server_stop(server). Interrupt handlers can be disabled if necessary.


Routes are regular functions with this signature:

Result (Request, Response)

These are registered using the function Server_route(server, path, handler). These should return ResultOK(NULL). If they return an error, the server will fall back to the Error 500 handler.

Error Handling

Special routes for Error 404 and 500 can be registered with Server_route404(server, handler) and Server_route500(server, handler).

Configuring the Server

Before starting the server, you may configure several settings:

Verbosity impacts the amount of logging the server will output. '0' is the default, and '3' will produce incredibly verbose logs. This is set with Server_setVerbosity(server, value).

Hooks impacts whether or not the server will listen for SIGINT and handle it. The default is 1, and it can be changed with Server_setHooks(server, useHooks).

Checking Request Information

  • request.path contains the path being routed.
  • Header_get(&request->headers, "name") can be used to get the value of an HTTP Request header. Returns NULL on failure. All headers are in lowercase, and Header_get is case-sensitive!
  • request.method contains the HTTP request method being used. This can be:
    • HTTPMethodGET - HTTP GET request
    • HTTPMethodPOST - HTTP POST request
    • HTTPMethodHEAD - HTTP HEAD request, same as GET except returns size sans-data
    • HTTPMethodUnknown - Any other HTTP request method.

Setting Response Information

  • response.status contains the HTTP response status code. This defaults to 200, except within error handlers.
  • Response_write(response, void *buffer, size_t size) can append information to the response body.
  • Response_printf(response, "format string", ...) can append text to the response body, using the same format as printf.
  • Header_set(&response->headers, "name", "value") can set a response header. All headers must be in LOWERCASE.


For an example, see test.c.


  • Add GET and POST parameter support
  • Add routing pattern matching, e.g. "/user/<userid>/profile"
  • Allow routes to filter by request method.


Simple C HTTP Server Library







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