#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <lwip/tcpip.h>
#include <lwip/sockets.h>
#include <netif/tapif.h>

struct netif netif;
unsigned char ipaddr[] = {192, 168, 101, 42};
unsigned char gw[] = {192, 168, 101, 1};
unsigned char netmask[] = {255, 255, 255, 0};
unsigned short port=4242;

static void init_func(void *arg){
	struct netif *rv = netif_add(&netif, 
			(void *) ipaddr,
			(void *) netmask,
			(void *) gw,
			NULL, tapif_init, tcpip_input);
	if (rv) {
		netif_set_default(&netif);
		netif_set_up(&netif);
		netif_set_link_up(&netif);
	}
}

int main(int argc, char *argv[]) {
	tcpip_init(init_func, NULL);
	sleep(1);
	int s = lwip_socket(AF_INET, SOCK_DGRAM, 0);
	printf("s=%d\n", s);
	struct sockaddr_in bindaddr = {
		.sin_family = AF_INET,
		.sin_port = htons(port),
		.sin_addr = IPADDR_ANY
	};
	struct sockaddr_in sender;
	unsigned int senderlen = sizeof(sender);
	lwip_bind(s, (void *) &bindaddr, sizeof(bindaddr));
	for (;;) {
		char buf[1024];
		int rv = lwip_recvfrom(s, buf, sizeof(buf) - 1, 0, (void *) &sender, &senderlen);
		if (rv > 0) {
			buf[rv] = 0;
			printf("echo %s\n", buf);
			lwip_sendto(s, buf, rv, 0, (void *) &sender, senderlen); 
		}
	}
	lwip_close(s);
}