#define _GNU_SOURCE

#include <sys/socket.h>

#include <dlfcn.h>

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include <netinet/in.h>

static int

port_is_okay(unsigned short port)

{

	char *p, *q;

	long l;

	p = getenv("NOPORT");

	while ((p != NULL) && (*p != '\0')) {

		l = strtol(p, &q, 10);

		if ((q == NULL) || (q == p)) {

			break;

		}

		if ((*q == '\0') || (*q == ',')) {

			if (port == l) {

				errno = ECONNREFUSED;

				return -1;

			}

		}

		p = q;

		p += strspn(p, ",");

	}

	return 0;

}

int

connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)

{

	unsigned short port;

	static int (*next_connect)(int, const struct sockaddr *, socklen_t);

	if (next_connect == NULL) {

		next_connect = dlsym(RTLD_NEXT, "connect");

		if (next_connect == NULL) {

			errno = ENOSYS;

			return -1;

		}

	}

	if (getenv("NOPORT") == NULL) {

		return next_connect(sockfd, addr, addrlen);

	}

	switch (addr->sa_family) {

	case AF_INET:

		port = ntohs(((struct sockaddr_in *)addr)->sin_port);

		if (port_is_okay(port) != 0) {

			return -1;

		}

		break;

	case AF_INET6:

		port = ntohs(((struct sockaddr_in6 *)addr)->sin6_port);

		if (port_is_okay(port) != 0) {

			return -1;

		}

		break;

	default:

		break;

	}

	return next_connect(sockfd, addr, addrlen);

}

ssize_t

sendto(int sockfd, const void *buf, size_t len, int flags,

       const struct sockaddr *dest_addr, socklen_t addrlen)

{

	unsigned short port;

	static int (*next_sendto)(int, const void *, size_t, int,

				  const struct sockaddr *, socklen_t);

	if (next_sendto == NULL) {

		next_sendto = dlsym(RTLD_NEXT, "sendto");

		if (next_sendto == NULL) {

			errno = ENOSYS;

			return -1;

		}

	}

	if (getenv("NOPORT") == NULL) {

		return next_sendto(sockfd, buf, len, flags, dest_addr, addrlen);

	}

	if (dest_addr != NULL) {

		switch (dest_addr->sa_family) {

		case AF_INET:

			port = ((struct sockaddr_in *)dest_addr)->sin_port;

			port = ntohs(port);

			if (port_is_okay(port) != 0) {

				return -1;

			}

			break;

		case AF_INET6:

			port = ((struct sockaddr_in6 *)dest_addr)->sin6_port;

			port = ntohs(port);

			if (port_is_okay(port) != 0) {

				return -1;

			}

			break;

		default:

			break;

		}

	}

	return next_sendto(sockfd, buf, len, flags, dest_addr, addrlen);

}