inz

snmpcproxy.c (raw)

/* 
 * Copyright (c) 2015 Santtu Lakkala
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#include <netinet/in.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <poll.h>
 
#include <stdio.h>
 
#define MAX_AGENTS 64
 
struct agent {
	const char *community;
	size_t c_len;
	struct sockaddr_in agent;
	struct sockaddr_in client;
};
 
int strmatchn(const char *a, size_t a_len, const char *b, size_t b_len)
{
	return a_len == b_len && !strncmp(a, b, a_len);
}
 
size_t find_agent(struct agent *agents, size_t n_agents, const char *community, size_t c_len)
{
	size_t i;
 
	for (i = 0; i < n_agents; i++) {
		if (strmatchn(agents[i].community, agents[i].c_len, community, c_len))
			break;
	}
	return i;
}
 
int set_agent(struct agent *agents, size_t *n_agents, const char *details)
{
	const char *colon = strchr(details, ':');
	size_t i;
	char buffer[256];
 
	if (!colon)
		return 0;
	i = find_agent(agents, *n_agents, details, colon - details);
	if (i == *n_agents) {
		if (i == MAX_AGENTS)
			return 0;
		(*n_agents)++;
		agents[i].community = details;
		agents[i].c_len = colon - details;
	}
 
	memset(&agents[i].client, 0, sizeof(agents[i].client));
	memset(&agents[i].agent, 0, sizeof(agents[i].agent));
 
	details = colon + 1;
	colon = strchr(details, ':');
 
	if (colon) {
		memcpy(buffer, details, colon - details);
		buffer[colon - details] = '\0';
 
		inet_aton(buffer, &agents[i].agent.sin_addr);
		agents[i].agent.sin_port = htons(atoi(colon + 1));
	} else {
		inet_aton(details, &agents[i].agent.sin_addr);
		agents[i].agent.sin_port = htons(161);
	}
 
	return 1;
 
}
 
int running = 1;
 
void sighand(int signo)
{
	(void)signo;
	running = 0;
}
 
int main(int argc, char **argv)
{
	struct agent agents[MAX_AGENTS];
	size_t n_agents;
	char buffer[8192];
	struct sockaddr_in serv = { 0 };
	struct pollfd pfds[MAX_AGENTS + 1];
 
	int i;
 
	serv.sin_family = AF_INET;
	serv.sin_addr.s_addr = htonl(INADDR_ANY);
	serv.sin_port = htons(161);
 
	signal(SIGINT, sighand);
 
	for (i = 1; i < argc; i++) {
		if (*argv[i] == '-') {
			const char *o = &argv[i][1];
			while (*o) {
				if (i + 1 >= argc)
					return 1;
 
				switch (*o++) {
				case 'l':
					if (!inet_aton(argv[++i], &serv.sin_addr))
						return 1;
					break;
				case 'p':
					serv.sin_port = htons(atoi(argv[++i]));
					break;
				case 'a':
					set_agent(agents, &n_agents, argv[++i]);
					break;
				default:
					return 1;
					break;
				}
			}
		} else {
			return 1;
		}
	}
 
	if ((pfds[0].fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror("Failed to create socket for listening: ");
		return 1;
	}
	pfds[0].events = POLLIN;
 
	for (i = 0; i < n_agents; i++) {
		if ((pfds[i + 1].fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
			perror("Failed to create socket for listening: ");
			return 1;
		}
		pfds[i + 1].events = POLLIN;
	}
 
	if (bind(pfds[0].fd, (const struct sockaddr *)&serv, sizeof(serv)) < 0) {
		perror("Failed to bind: ");
		return 1;
	}
 
	while (running) {
		int n;
 
		n = poll(pfds, n_agents + 1, -1);
 
		if (pfds[0].revents & POLLIN) {
			struct sockaddr_in c;
			socklen_t len = sizeof(c);
			ssize_t r = recvfrom(pfds[0].fd, buffer, sizeof(buffer), 0,
					     (struct sockaddr *)&c, &len);
			if (r == 0)
				break;
			if (r > 6) {
				int len = (unsigned char)buffer[6];
				if (r > 6 + len) {
					i = find_agent(agents, n_agents, buffer + 7, len);
 
					if (i < n_agents) {
						memcpy(&agents[i].client, &c, len);
						sendto(pfds[i + 1].fd, buffer, r, 0,
						       (const struct sockaddr *)&agents[i].agent, sizeof(struct sockaddr_in));
					}
				}
				printf("%.*s\n", len, buffer + 7);
			}
			n--;
		}
 
		for (i = 0; n && i < n_agents; i++) {
			if (pfds[i + 1].revents & POLLIN) {
				ssize_t r = recv(pfds[i + 1].fd, buffer, sizeof(buffer), 0);
				if (r == 0)
					break;
				if (r > 0)
					sendto(pfds[0].fd, buffer, r, 0, (const struct sockaddr *)&agents[i].client, sizeof(struct sockaddr_in));
				n--;
			}
		}
	}
 
	return 0;
}