Micro TCP is a network stack designed to be easily embeddable, portable and thoroughly tested. It implements ARP, IP, ICMP and TCP. The ideal use-cases are user-space networking and using it in bare-metal microcontrollers.

Usage

To use it, you need to instanciate a microtcp_t structure using either the microtcp_create or microtcp_create_using_callbacks constructor.

The basic constructor microtcp_create behaves differently based on your platform because it needs to plug the stack to the system. At the moment it's assumed a Linux host and the instanciated stack is associated to a tap device tap0 with IP 10.0.0.5/24. The stack produces packets with IP 10.0.0.4/24 (being honest, this configuration is only useful for testing).

It's also possible to configure the stack explicitly using the microtcp_create_using_callbacks, which lets the caller provide the callbacks to input the ethernet frames to the stack and send frames back on the wire. Each system will need it's specific implementation of these callbacks.

Each instance of MicroTCP (without considering the callbacks) is completely isolated from the others, therefore, if your specific callback implementation allows it, you can have as many instances as you like! Usually the callbacks introduce a dependency between the stacks because the system is one big global state.

Once instanciated, you can free the stack using microtcp_destroy.

Once a microtcp_t instance is created, you can create and use sockets with methods analogous to the BSD socket API. For instance, here's a simple TCP echo server which replies to messages with the message itself prefixed with "echo: ":

#include <microtcp.h>

int main(void)
{
    microtcp_t *mtcp = microtcp_create();
    
    uint16_t port = 80;
    microtcp_socket_t *server = microtcp_open(mtcp, port, NULL);
    
    while (1) {

        microtcp_socket_t *client = microtcp_accept(server, false, NULL);

        char buffer[1024];
        size_t num = microtcp_recv(client, buffer, sizeof(buffer), NULL);
        microtcp_send(client, "echo: ", 6, NULL);
        microtcp_send(client, buffer, num, NULL);

        microtcp_close(client);
    }
    
    microtcp_close(server);
    microtcp_destroy(mtcp);
    return 0;
}

// NOTE: Errors checks were omitted for readability's sake.
//       If you want to use this code, you probably want to
//       add some checks!

Contributing

The build result is a header and a .c obtained as an amalgamation of all the source files. Any header included in the source files must be guarded by a #ifndef MICROTCP_AMALGAMATION.