boot-it/boot-it.c

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

#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#include "bootp.h"

static void usage(int argc, char **argv)
{
	const char *name = argc ? argv[0] : "boot-it";

	printf("usage: %s [-H <bind to this host>] [-P <bind to this port>]\n",
			name);
	exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
	int c;
	int errct = 0;
	const char *bind_host = NULL;
	const char *bind_port = BOOTP_SERVER_PORT;

	while ((c = getopt(argc, argv, ":H:p:h")) != -1) {
		switch (c) {
		case 'H':
			bind_host = optarg;
			break;
		case 'p':
			bind_port = optarg;
			break;
		case ':':
			fprintf(stderr, "option -%c requries an operand\n", optopt);
			errct++;
			break;
		case '?':
			fprintf(stderr, "unrecognized option -%c\n", optopt);
			errct++;
			break;
		case 'h':
			usage(argc, argv);
		}
	}

	if (errct)
		usage(argc, argv);


	struct addrinfo hint = {
		.ai_family = AF_INET,
		.ai_socktype = SOCK_DGRAM,
		.ai_flags = AI_PASSIVE,
	};
	struct addrinfo *res;
	int s = getaddrinfo(bind_host, bind_port, &hint, &res);
	if (s != 0) {
		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
		exit(EXIT_FAILURE);
	}

	int sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
	if (sock == -1) {
		fprintf(stderr, "could get socket: %s\n", strerror(errno));
		return 1;
	}

	s = bind(sock, res->ai_addr, res->ai_addrlen);
	if (!s) {
		fprintf(stderr, "bind failed: %s\n", strerror(errno));
		return 1;
	}

	freeaddrinfo(res);

	for (;;) {
		struct sockaddr_storage peer_addr;
		socklen_t peer_addr_len = sizeof(peer_addr);
		char buf[512];
		ssize_t nread = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *)&peer_addr, &peer_addr_len);
		if (nread == -1)
			continue;

		char host[NI_MAXHOST], service[NI_MAXSERV];

		s = getnameinfo((struct sockaddr *)&peer_addr,
				peer_addr_len, host, NI_MAXHOST,
				service, NI_MAXSERV, NI_NUMERICSERV|NI_NUMERICHOST);

		if (!s) {
			fprintf(stderr, "getnameinfo: %s\n", gai_strerror(s));
			strncpy(host, "(unknown host)", sizeof(host));
			strncpy(service, "(unknown service)", sizeof(service));
		}

		printf("recv %zd bytes from %s:%s\n", nread, host, service);
	}

	return 0;
}