1/*
2 * Copyright (c) 2003
3 *	Fraunhofer Institute for Open Communication Systems (FhG Fokus).
4 *	All rights reserved.
5 *
6 * Author: Harti Brandt <harti@freebsd.org>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $Begemot: bsnmp/snmpd/trans_udp.c,v 1.5 2005/10/04 08:46:56 brandt_h Exp $
30 *
31 * UDP transport
32 */
33#include <sys/types.h>
34#include <sys/queue.h>
35#include <sys/ucred.h>
36
37#include <stdbool.h>
38#include <stdlib.h>
39#include <syslog.h>
40#include <string.h>
41#include <errno.h>
42#include <unistd.h>
43
44#include <netinet/in.h>
45#include <arpa/inet.h>
46
47#include "snmpmod.h"
48#include "snmpd.h"
49#include "trans_udp.h"
50#include "tree.h"
51#include "oid.h"
52
53static int udp_start(void);
54static int udp_stop(int);
55static void udp_close_port(struct tport *);
56static int udp_init_port(struct tport *);
57static ssize_t udp_send(struct tport *, const u_char *, size_t,
58    const struct sockaddr *, size_t);
59static ssize_t udp_recv(struct tport *, struct port_input *);
60
61/* exported */
62const struct transport_def udp_trans = {
63	"udp",
64	OIDX_begemotSnmpdTransUdp,
65	udp_start,
66	udp_stop,
67	udp_close_port,
68	udp_init_port,
69	udp_send,
70	udp_recv
71};
72static struct transport *my_trans;
73
74static int
75udp_start(void)
76{
77	return (trans_register(&udp_trans, &my_trans));
78}
79
80static int
81udp_stop(int force __unused)
82{
83	if (my_trans != NULL)
84		if (trans_unregister(my_trans) != 0)
85			return (SNMP_ERR_GENERR);
86	return (SNMP_ERR_NOERROR);
87}
88
89/*
90 * A UDP port is ready
91 */
92static void
93udp_input(int fd __unused, void *udata)
94{
95	struct udp_port *p = udata;
96
97	p->input.peerlen = sizeof(p->ret);
98	snmpd_input(&p->input, &p->tport);
99}
100
101/*
102 * Create a UDP socket and bind it to the given port
103 */
104static int
105udp_init_port(struct tport *tp)
106{
107	struct udp_port *p = (struct udp_port *)tp;
108	struct sockaddr_in addr;
109	u_int32_t ip;
110	const int on = 1;
111
112	if ((p->input.fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
113		syslog(LOG_ERR, "creating UDP socket: %m");
114		return (SNMP_ERR_RES_UNAVAIL);
115	}
116	ip = (p->addr[0] << 24) | (p->addr[1] << 16) | (p->addr[2] << 8) |
117	    p->addr[3];
118	memset(&addr, 0, sizeof(addr));
119	addr.sin_addr.s_addr = htonl(ip);
120	addr.sin_port = htons(p->port);
121	addr.sin_family = AF_INET;
122	addr.sin_len = sizeof(addr);
123	if (addr.sin_addr.s_addr == INADDR_ANY) {
124		if (setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
125		    sizeof(on)) == -1) {
126			syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
127			close(p->input.fd);
128			p->input.fd = -1;
129			return (SNMP_ERR_GENERR);
130		}
131		p->recvdstaddr = true;
132	}
133	if (bind(p->input.fd, (struct sockaddr *)&addr, sizeof(addr))) {
134		if (errno == EADDRNOTAVAIL) {
135			close(p->input.fd);
136			p->input.fd = -1;
137			return (SNMP_ERR_INCONS_NAME);
138		}
139		syslog(LOG_ERR, "bind: %s:%u %m", inet_ntoa(addr.sin_addr),
140		    p->port);
141		close(p->input.fd);
142		p->input.fd = -1;
143		return (SNMP_ERR_GENERR);
144	}
145	if ((p->input.id = fd_select(p->input.fd, udp_input,
146	    p, NULL)) == NULL) {
147		close(p->input.fd);
148		p->input.fd = -1;
149		return (SNMP_ERR_GENERR);
150	}
151	return (SNMP_ERR_NOERROR);
152}
153
154/*
155 * Create a new SNMP Port object and start it, if we are not
156 * in initialization mode. The arguments are in host byte order.
157 */
158static int
159udp_open_port(u_int8_t *addr, u_int32_t udp_port, struct udp_port **pp)
160{
161	struct udp_port *port;
162	int err;
163
164	if (udp_port > 0xffff)
165		return (SNMP_ERR_NO_CREATION);
166	if ((port = malloc(sizeof(*port))) == NULL)
167		return (SNMP_ERR_GENERR);
168	memset(port, 0, sizeof(*port));
169
170	/* initialize common part */
171	port->tport.index.len = 5;
172	port->tport.index.subs[0] = addr[0];
173	port->tport.index.subs[1] = addr[1];
174	port->tport.index.subs[2] = addr[2];
175	port->tport.index.subs[3] = addr[3];
176	port->tport.index.subs[4] = udp_port;
177
178	port->addr[0] = addr[0];
179	port->addr[1] = addr[1];
180	port->addr[2] = addr[2];
181	port->addr[3] = addr[3];
182	port->port = udp_port;
183
184	port->input.fd = -1;
185	port->input.id = NULL;
186	port->input.stream = 0;
187	port->input.cred = 0;
188	port->input.peer = (struct sockaddr *)&port->ret;
189	port->input.peerlen = sizeof(port->ret);
190
191	trans_insert_port(my_trans, &port->tport);
192
193	if (community != COMM_INITIALIZE &&
194	    (err = udp_init_port(&port->tport)) != SNMP_ERR_NOERROR) {
195		udp_close_port(&port->tport);
196		return (err);
197	}
198	*pp = port;
199	return (SNMP_ERR_NOERROR);
200}
201
202/*
203 * Close an SNMP port
204 */
205static void
206udp_close_port(struct tport *tp)
207{
208	struct udp_port *port = (struct udp_port *)tp;
209
210	snmpd_input_close(&port->input);
211	trans_remove_port(tp);
212	free(port);
213}
214
215/*
216 * Send something
217 */
218static ssize_t
219udp_send(struct tport *tp, const u_char *buf, size_t len,
220    const struct sockaddr *addr, size_t addrlen)
221{
222	struct udp_port *p = (struct udp_port *)tp;
223	struct cmsghdr *cmsg;
224	struct msghdr msg;
225	char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
226	struct iovec iov;
227
228	iov.iov_base = __DECONST(void*, buf);
229	iov.iov_len = len;
230
231	msg.msg_flags = 0;
232	msg.msg_iov = &iov;
233	msg.msg_iovlen = 1;
234	msg.msg_name = __DECONST(void *, addr);
235	msg.msg_namelen = addrlen;
236
237	if (p->recvdstaddr) {
238		msg.msg_control = cbuf;
239		msg.msg_controllen = sizeof(cbuf);
240
241		cmsg = CMSG_FIRSTHDR(&msg);
242		cmsg->cmsg_level = IPPROTO_IP;
243		cmsg->cmsg_type = IP_SENDSRCADDR;
244		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
245		memcpy(CMSG_DATA(cmsg), &p->dstaddr, sizeof(struct in_addr));
246	} else {
247		msg.msg_control = NULL;
248		msg.msg_controllen = 0;
249	}
250
251	return (sendmsg(p->input.fd, &msg, 0));
252}
253
254static void
255check_priv_dgram(struct port_input *pi, struct sockcred *cred)
256{
257
258	/* process explicitly sends credentials */
259	if (cred)
260		pi->priv = (cred->sc_euid == 0);
261	else
262		pi->priv = 0;
263}
264
265/*
266 * Input from a datagram socket.
267 * Each receive should return one datagram.
268 */
269static ssize_t
270udp_recv(struct tport *tp, struct port_input *pi)
271{
272	u_char embuf[1000];
273	char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
274	    CMSG_SPACE(sizeof(struct in_addr))];
275	struct udp_port *p = (struct udp_port *)tp;
276	struct msghdr msg;
277	struct iovec iov[1];
278	ssize_t len;
279	struct cmsghdr *cmsg;
280	struct sockcred *cred = NULL;
281
282	if (pi->buf == NULL) {
283		/* no buffer yet - allocate one */
284		if ((pi->buf = buf_alloc(0)) == NULL) {
285			/* ups - could not get buffer. Read away input
286			 * and drop it */
287			(void)recvfrom(pi->fd, embuf, sizeof(embuf),
288			    0, NULL, NULL);
289			/* return error */
290			return (-1);
291		}
292		pi->buflen = buf_size(0);
293	}
294
295	/* try to get a message */
296	msg.msg_name = pi->peer;
297	msg.msg_namelen = pi->peerlen;
298	msg.msg_iov = iov;
299	msg.msg_iovlen = 1;
300	memset(cbuf, 0, sizeof(cbuf));
301	msg.msg_control = cbuf;
302	msg.msg_controllen = sizeof(cbuf);
303	msg.msg_flags = 0;
304
305	iov[0].iov_base = pi->buf;
306	iov[0].iov_len = pi->buflen;
307
308	len = recvmsg(pi->fd, &msg, 0);
309
310	if (len == -1 || len == 0)
311		/* receive error */
312		return (-1);
313
314	if (msg.msg_flags & MSG_TRUNC) {
315		/* truncated - drop */
316		snmpd_stats.silentDrops++;
317		snmpd_stats.inTooLong++;
318		return (-1);
319	}
320
321	pi->length = (size_t)len;
322
323	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
324	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
325		if (cmsg->cmsg_level == IPPROTO_IP &&
326		    cmsg->cmsg_type == IP_RECVDSTADDR)
327			memcpy(&p->dstaddr, CMSG_DATA(cmsg),
328			    sizeof(struct in_addr));
329		if (cmsg->cmsg_level == SOL_SOCKET &&
330		    cmsg->cmsg_type == SCM_CREDS)
331			cred = (struct sockcred *)CMSG_DATA(cmsg);
332	}
333
334	if (pi->cred)
335		check_priv_dgram(pi, cred);
336
337	return (0);
338}
339
340/*
341 * Port table
342 */
343int
344op_snmp_port(struct snmp_context *ctx, struct snmp_value *value,
345    u_int sub, u_int iidx, enum snmp_op op)
346{
347	asn_subid_t which = value->var.subs[sub-1];
348	struct udp_port *p;
349	u_int8_t addr[4];
350	u_int32_t port;
351
352	switch (op) {
353
354	  case SNMP_OP_GETNEXT:
355		if ((p = (struct udp_port *)trans_next_port(my_trans,
356		    &value->var, sub)) == NULL)
357			return (SNMP_ERR_NOSUCHNAME);
358		index_append(&value->var, sub, &p->tport.index);
359		break;
360
361	  case SNMP_OP_GET:
362		if ((p = (struct udp_port *)trans_find_port(my_trans,
363		    &value->var, sub)) == NULL)
364			return (SNMP_ERR_NOSUCHNAME);
365		break;
366
367	  case SNMP_OP_SET:
368		p = (struct udp_port *)trans_find_port(my_trans,
369		    &value->var, sub);
370		ctx->scratch->int1 = (p != NULL);
371
372		if (which != LEAF_begemotSnmpdPortStatus)
373			abort();
374		if (!TRUTH_OK(value->v.integer))
375			return (SNMP_ERR_WRONG_VALUE);
376
377		ctx->scratch->int2 = TRUTH_GET(value->v.integer);
378
379		if (ctx->scratch->int2) {
380			/* open an SNMP port */
381			if (p != NULL)
382				/* already open - do nothing */
383				return (SNMP_ERR_NOERROR);
384
385			if (index_decode(&value->var, sub, iidx, addr, &port))
386				return (SNMP_ERR_NO_CREATION);
387			return (udp_open_port(addr, port, &p));
388
389		} else {
390			/* close SNMP port - do in commit */
391		}
392		return (SNMP_ERR_NOERROR);
393
394	  case SNMP_OP_ROLLBACK:
395		p = (struct udp_port *)trans_find_port(my_trans,
396		    &value->var, sub);
397		if (ctx->scratch->int1 == 0) {
398			/* did not exist */
399			if (ctx->scratch->int2 == 1) {
400				/* created */
401				if (p != NULL)
402					udp_close_port(&p->tport);
403			}
404		}
405		return (SNMP_ERR_NOERROR);
406
407	  case SNMP_OP_COMMIT:
408		p = (struct udp_port *)trans_find_port(my_trans,
409		    &value->var, sub);
410		if (ctx->scratch->int1 == 1) {
411			/* did exist */
412			if (ctx->scratch->int2 == 0) {
413				/* delete */
414				if (p != NULL)
415					udp_close_port(&p->tport);
416			}
417		}
418		return (SNMP_ERR_NOERROR);
419
420	  default:
421		abort();
422	}
423
424	/*
425	 * Come here to fetch the value
426	 */
427	switch (which) {
428
429	  case LEAF_begemotSnmpdPortStatus:
430		value->v.integer = 1;
431		break;
432
433	  default:
434		abort();
435	}
436
437	return (SNMP_ERR_NOERROR);
438}
439