C - iroh

Platform	Architectures
Linux	x86_64 (glibc)
macOS	arm64
Windows	x86_64

Header: irohnet.h, checked into the repo
Examples: main.c and the multi-thread examples
All languages: platform support matrix

iroh-c-ffi is a raw C API generated with safer-ffi — unlike the Python, Swift, Kotlin, and JavaScript bindings, it isn’t built on iroh-ffi/uniffi. There are no prebuilt binaries; you build the static/shared library from source and link against it.

Install

git clone https://github.com/n0-computer/iroh-c-ffi
cd iroh-c-ffi
cargo build --release

This produces target/release/libiroh_c_ffi.{a,so,dylib}. The matching header is already checked in as irohnet.h; regenerate it only if you’re tracking an API change:

cargo run --features headers --bin generate_headers --release

Hello, iroh

#include <stdio.h>
#include <string.h>
#include "irohnet.h"

int main(void) {
  char alpn[] = "hello-c-ffi/0";
  slice_ref_uint8_t alpn_slice;
  alpn_slice.ptr = (uint8_t *) alpn;
  alpn_slice.len = strlen(alpn);

  EndpointConfig_t config = endpoint_config_default();
  endpoint_config_add_alpn(&config, alpn_slice);

  Endpoint_t *ep = endpoint_default();
  if (endpoint_bind(&config, NULL, NULL, &ep) != 0) {
    fprintf(stderr, "failed to bind\n");
    return 1;
  }
  endpoint_online(&ep, 5000);

  EndpointAddr_t addr = endpoint_addr_default();
  endpoint_addr(&ep, &addr);
  printf("endpoint id: %s\n", public_key_as_base32(&addr.id));

  endpoint_free(ep);
  endpoint_config_free(config);
  return 0;
}

Build and link against the library from the previous step:

cc -o hello hello.c -L target/release -liroh_c_ffi -lm

This binds an endpoint with a single ALPN, waits up to 5 seconds for a home relay, and prints the endpoint id. See the CI workflow for the extra link flags Windows needs.

Next steps

main.c example

A full server/client pair: bind, accept, send, and receive over uni- and bi-directional streams.

Multi-threaded examples

multi-thread-server.c, multi-thread-client.c, and single-thread-server.c for handling concurrent connections.

iroh-c-ffi repository

Source, generated header, and issue tracker for the C bindings.

​Install

​Hello, iroh

​Next steps