echo_server.c

#include <stdio.h>
#include <stdlib.h>

#include <uv.h>
// ------------------------------------------------------------------------------------------------
typedef struct {
	uv_write_t req;
	uv_buf_t   buf;
} write_req_t;

void cb_alloc_buffer(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf);
void cb_echo_write(uv_write_t* req, int status);
void cb_echo_read(uv_stream_t* client, ssize_t nread, const uv_buf_t* buf);
void cb_on_new_connection(uv_stream_t* server, int status);
void free_write_req(uv_write_t* req);
// ------------------------------------------------------------------------------------------------
int main() {
	uv_loop_t* loop = uv_default_loop();

	uv_tcp_t server;
	uv_tcp_init(loop, &server);

	struct sockaddr_in addr;
	uv_ip4_addr("0.0.0.0", 12345, &addr);
	uv_tcp_bind(&server, (const struct sockaddr*)&addr, 0);

	int r = uv_listen((uv_stream_t*)&server, 2, cb_on_new_connection);
	if (r) {
		fprintf(stderr, "Listen error %s\n", uv_strerror(r));
		return 1;
	}
	return uv_run(loop, UV_RUN_DEFAULT);
}
// ------------------------------------------------------------------------------------------------
// allocate buffer callback
void cb_alloc_buffer(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
	buf->base = (char*)malloc(suggested_size);
	buf->len  = suggested_size;
}

// echo write callback
void cb_echo_write(uv_write_t* req, int status) {
	if (status) {
		fprintf(stderr, "Write error %s\n", uv_strerror(status));
	}
	free_write_req(req);
}

// echo read callback
void cb_echo_read(uv_stream_t* client, ssize_t nread, const uv_buf_t* buf) {
	if (nread > 0) {
		write_req_t* req = (write_req_t*)malloc(sizeof(write_req_t));
		req->buf         = uv_buf_init(buf->base, nread);
		uv_write((uv_write_t*)req, client, &req->buf, 1, cb_echo_write);
		return;
	}
	if (nread < 0) {
		if (nread != UV_EOF)
			fprintf(stderr, "Read error %s\n", uv_err_name(nread));
		uv_close((uv_handle_t*)client, NULL);
	}

	free(buf->base);
}

void cb_on_new_connection(uv_stream_t* server, int status) {
	if (status < 0) {
		fprintf(stderr, "New connection error %s\n", uv_strerror(status));
		return;
	}
	uv_loop_t* loop = uv_default_loop();

	uv_tcp_t* client = (uv_tcp_t*)malloc(sizeof(uv_tcp_t));
	uv_tcp_init(loop, client);
	if (uv_accept(server, (uv_stream_t*)client) == 0) {
		uv_read_start((uv_stream_t*)client, cb_alloc_buffer, cb_echo_read);
	}
	else {
		uv_close((uv_handle_t*)client, NULL);
	}
}

void free_write_req(uv_write_t* req) {
	write_req_t* wr = (write_req_t*)req;
	free(wr->buf.base);
	free(wr);
}