libevent websocket client test

ws-client.cpp

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/event.h>
#include <event2/dns.h>

#include <arpa/inet.h>

#include <iostream>
using namespace std;

#define htonll(x) ((1==htonl(1)) ? (x) : ((uint64_t)htonl((x) & 0xFFFFFFFF) << 32) | htonl((x) >> 32))
#define ntohll(x) htonll(x)

const char* uri = "/echo";
const char* host = "127.0.0.1";
unsigned short port = 1234;

const char* fixed_key = "dGhlIHNhbXBsZSBub25jZQ==";
const char* fixed_accept = "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=";

bool upgraded = false;

static void send(evbuffer* buf, const char* msg){

	size_t len = strlen(msg);

	uint8_t a = 0;
	a |= 1 << 7;  //fin
	a |= 1; //text frame
	
	uint8_t b = 0;
	b |= 1 << 7; //mask
	
	uint16_t c = 0;
	uint64_t d = 0;

	//payload len
	if(len < 126){
		b |= len; 
	}
	else if(len < (1 << 16)){
		b |= 126;
		c = htons(len);
	}else{
		b |= 127;
		d = htonll(len);
	}

	
	evbuffer_add(buf, &a, 1);
	evbuffer_add(buf, &b, 1);

	if(c) evbuffer_add(buf, &c, sizeof(c));
	else if(d) evbuffer_add(buf, &d, sizeof(d));

	uint8_t mask_key[4] = {1, 2, 3, 4};  //should be random
	evbuffer_add(buf, &mask_key, 4);

	uint8_t m;
	for(int i = 0; i < len; i++){
		m = msg[i] ^ mask_key[i%4];
		evbuffer_add(buf, &m, 1); 
	}	
}

static void receive(evbuffer* buf){
	auto data_len = evbuffer_get_length(buf);
	if(data_len < 2)
		return;

	unsigned char* data = evbuffer_pullup(buf, data_len);

	int fin = !!(*data & 0x80);
	int opcode = *data & 0x0F;
	int mask = !!(*(data+1) & 0x80);
	uint64_t payload_len =  *(data+1) & 0x7F;

	size_t header_len = 2 + (mask ? 4 : 0);
	
	if(payload_len < 126){
		if(header_len > data_len)
			return;

	}else if(payload_len == 126){
		header_len += 2;
		if(header_len > data_len)
			return;

		payload_len = ntohs(*(uint16_t*)(data+2));

	}else if(payload_len == 127){
		header_len += 8;
		if(header_len > data_len)
			return;

		payload_len = ntohll(*(uint64_t*)(data+2));
	}

	if(header_len + payload_len > data_len)
		return;


	const unsigned char* mask_key = data + header_len - 4;

	cout << "data_len " << data_len << " mask " << mask << " head_len " << header_len << " payload_len " << payload_len << endl;

	for(int i = 0; mask && i < payload_len; i++)
		data[header_len + i] ^= mask_key[i%4];


	if(opcode == 0x01)
		cout << ">" <<string((const char*)data + header_len, payload_len) << "<"<< endl;



	if(!fin){
		cout << "fram to be continue..." << endl;
	}

	
	evbuffer_drain(buf, header_len + payload_len);

	//next frame
	receive(buf);
}


static void request(bufferevent* bev){

	cout << "request" << endl;

	auto out = bufferevent_get_output(bev);
	evbuffer_add_printf(out, "GET %s HTTP/1.1\r\n", uri);
	evbuffer_add_printf(out, "Host:%s:%d\r\n",host, port);
	evbuffer_add_printf(out, "Upgrade:websocket\r\n");
	evbuffer_add_printf(out, "Connection:upgrade\r\n");
	evbuffer_add_printf(out, "Sec-WebSocket-Key:%s\r\n", fixed_key);
	evbuffer_add_printf(out, "Sec-WebSocket-Version:13\r\n");
	evbuffer_add_printf(out, "Origin:http://%s:%d\r\n",host, port); //missing this key will lead to 403 response.

	evbuffer_add_printf(out, "\r\n");
}

static void read_cb(bufferevent* bev, void* ptr){

	cout << "read cb" << endl;
	auto input = bufferevent_get_input(bev);


	if(!upgraded){

		auto data_len = evbuffer_get_length(input);
		unsigned char* data = evbuffer_pullup(input, data_len);

		if(!strstr((const char*)data, "\r\n\r\n"))
			return;

		if(strncmp((const char*)data, "HTTP/1.1 101", strlen("HTTP/1.1 101")) != 0
				|| !strstr((const char*)data, fixed_accept)){
			cout << string((const char*)data, data_len) << endl;
			cout << "websocket upgrade fail!" << endl;
		}else{
			//drain 
			evbuffer_drain(input, data_len);

			upgraded = true;

			send(bufferevent_get_output(bev), "hello");

			char long_msg[1024];
			memset(long_msg, '#', sizeof(long_msg));
			long_msg[0]= 'A';
			long_msg[sizeof(long_msg)-2]= 'E';
			long_msg[sizeof(long_msg)-1]= 0;

			send(bufferevent_get_output(bev), long_msg);

			char longlong_msg[(1<< 16) + 10];
			memset(longlong_msg, '#', sizeof(longlong_msg));
			longlong_msg[0]= 'A';
			longlong_msg[sizeof(longlong_msg)-2]= 'X';
			longlong_msg[sizeof(longlong_msg)-1]= 0;

			send(bufferevent_get_output(bev), longlong_msg);

		}
	}else{
		//handle frame
		receive(input);
	}

	
}

static void write_cb(bufferevent* bev, void* ptr){
	cout << "write cb" << endl;
}

static void event_cb(bufferevent* bev, short events, void* ptr){
	if(events & BEV_EVENT_CONNECTED){
		cout << "connected" << endl;
		request(bev);
	}else{
		cout << "diconnected " << events << endl;
	}
}


int main(){

	auto base = event_base_new();
	auto dns_base = evdns_base_new(base, 1);

	auto bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE|BEV_OPT_DEFER_CALLBACKS);

	bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
	bufferevent_enable(bev, EV_READ|EV_WRITE);

	bufferevent_socket_connect_hostname(bev, dns_base, AF_INET, host, port); 
	
	
	event_base_dispatch(base);

	return 0;
}

ws-server.go

package main

import (
        "golang.org/x/net/websocket"
        "log"
        "net/http"
)

func EchoServer(ws *websocket.Conn) {

        for {
                var msg string
                if err := websocket.Message.Receive(ws, &msg); err != nil {
                        log.Println("receive msg fail!!!")
                        return
                } else {
                        log.Println("msg len", len(msg))
                        log.Println(msg)

                        websocket.Message.Send(ws, msg)
                }
        }
}

func main() {
        http.Handle("/echo", websocket.Handler(EchoServer))
        log.Fatal(http.ListenAndServe(":1234", nil))
}

Reference: https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers