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	NULL
72};
73static struct transport *my_trans;
74
75static int
76udp_start(void)
77{
78	return (trans_register(&udp_trans, &my_trans));
79}
80
81static int
82udp_stop(int force __unused)
83{
84	if (my_trans != NULL)
85		if (trans_unregister(my_trans) != 0)
86			return (SNMP_ERR_GENERR);
87	return (SNMP_ERR_NOERROR);
88}
89
90/*
91 * A UDP port is ready
92 */
93static void
94udp_input(int fd __unused, void *udata)
95{
96	struct udp_port *p = udata;
97
98	p->input.peerlen = sizeof(p->ret);
99	snmpd_input(&p->input, &p->tport);
100}
101
102/*
103 * Create a UDP socket and bind it to the given port
104 */
105static int
106udp_init_port(struct tport *tp)
107{
108	struct udp_port *p = (struct udp_port *)tp;
109	struct sockaddr_in addr;
110	u_int32_t ip;
111	const int on = 1;
112
113	if ((p->input.fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
114		syslog(LOG_ERR, "creating UDP socket: %m");
115		return (SNMP_ERR_RES_UNAVAIL);
116	}
117	ip = (p->addr[0] << 24) | (p->addr[1] << 16) | (p->addr[2] << 8) |
118	    p->addr[3];
119	memset(&addr, 0, sizeof(addr));
120	addr.sin_addr.s_addr = htonl(ip);
121	addr.sin_port = htons(p->port);
122	addr.sin_family = AF_INET;
123	addr.sin_len = sizeof(addr);
124	if (addr.sin_addr.s_addr == INADDR_ANY) {
125		if (setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
126		    sizeof(on)) == -1) {
127			syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
128			close(p->input.fd);
129			p->input.fd = -1;
130			return (SNMP_ERR_GENERR);
131		}
132		p->recvdstaddr = true;
133	}
134	if (bind(p->input.fd, (struct sockaddr *)&addr, sizeof(addr))) {
135		if (errno == EADDRNOTAVAIL) {
136			close(p->input.fd);
137			p->input.fd = -1;
138			return (SNMP_ERR_INCONS_NAME);
139		}
140		syslog(LOG_ERR, "bind: %s:%u %m", inet_ntoa(addr.sin_addr),
141		    p->port);
142		close(p->input.fd);
143		p->input.fd = -1;
144		return (SNMP_ERR_GENERR);
145	}
146	if ((p->input.id = fd_select(p->input.fd, udp_input,
147	    p, NULL)) == NULL) {
148		close(p->input.fd);
149		p->input.fd = -1;
150		return (SNMP_ERR_GENERR);
151	}
152	return (SNMP_ERR_NOERROR);
153}
154
155/*
156 * Create a new SNMP Port object and start it, if we are not
157 * in initialization mode. The arguments are in host byte order.
158 */
159static int
160udp_open_port(u_int8_t *addr, u_int32_t udp_port, struct udp_port **pp)
161{
162	struct udp_port *port;
163	int err;
164
165	if (udp_port > 0xffff)
166		return (SNMP_ERR_NO_CREATION);
167	if ((port = malloc(sizeof(*port))) == NULL)
168		return (SNMP_ERR_GENERR);
169	memset(port, 0, sizeof(*port));
170
171	/* initialize common part */
172	port->tport.index.len = 5;
173	port->tport.index.subs[0] = addr[0];
174	port->tport.index.subs[1] = addr[1];
175	port->tport.index.subs[2] = addr[2];
176	port->tport.index.subs[3] = addr[3];
177	port->tport.index.subs[4] = udp_port;
178
179	port->addr[0] = addr[0];
180	port->addr[1] = addr[1];
181	port->addr[2] = addr[2];
182	port->addr[3] = addr[3];
183	port->port = udp_port;
184
185	port->input.fd = -1;
186	port->input.id = NULL;
187	port->input.stream = 0;
188	port->input.cred = 0;
189	port->input.peer = (struct sockaddr *)&port->ret;
190	port->input.peerlen = sizeof(port->ret);
191
192	trans_insert_port(my_trans, &port->tport);
193
194	if (community != COMM_INITIALIZE &&
195	    (err = udp_init_port(&port->tport)) != SNMP_ERR_NOERROR) {
196		udp_close_port(&port->tport);
197		return (err);
198	}
199	*pp = port;
200	return (SNMP_ERR_NOERROR);
201}
202
203/*
204 * Close an SNMP port
205 */
206static void
207udp_close_port(struct tport *tp)
208{
209	struct udp_port *port = (struct udp_port *)tp;
210
211	snmpd_input_close(&port->input);
212	trans_remove_port(tp);
213	free(port);
214}
215
216/*
217 * Send something
218 */
219static ssize_t
220udp_send(struct tport *tp, const u_char *buf, size_t len,
221    const struct sockaddr *addr, size_t addrlen)
222{
223	struct udp_port *p = (struct udp_port *)tp;
224	struct cmsghdr *cmsg;
225	struct msghdr msg;
226	char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
227	struct iovec iov;
228
229	iov.iov_base = __DECONST(void*, buf);
230	iov.iov_len = len;
231
232	msg.msg_flags = 0;
233	msg.msg_iov = &iov;
234	msg.msg_iovlen = 1;
235	msg.msg_name = __DECONST(void *, addr);
236	msg.msg_namelen = addrlen;
237
238	if (p->recvdstaddr) {
239		msg.msg_control = cbuf;
240		msg.msg_controllen = sizeof(cbuf);
241
242		cmsg = CMSG_FIRSTHDR(&msg);
243		cmsg->cmsg_level = IPPROTO_IP;
244		cmsg->cmsg_type = IP_SENDSRCADDR;
245		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
246		memcpy(CMSG_DATA(cmsg), &p->dstaddr, sizeof(struct in_addr));
247	} else {
248		msg.msg_control = NULL;
249		msg.msg_controllen = 0;
250	}
251
252	return (sendmsg(p->input.fd, &msg, 0));
253}
254
255static void
256check_priv_dgram(struct port_input *pi, struct sockcred *cred)
257{
258
259	/* process explicitly sends credentials */
260	if (cred)
261		pi->priv = (cred->sc_euid == 0);
262	else
263		pi->priv = 0;
264}
265
266/*
267 * Input from a datagram socket.
268 * Each receive should return one datagram.
269 */
270static ssize_t
271udp_recv(struct tport *tp, struct port_input *pi)
272{
273	u_char embuf[1000];
274	char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
275	    CMSG_SPACE(sizeof(struct in_addr))];
276	struct udp_port *p = (struct udp_port *)tp;
277	struct msghdr msg;
278	struct iovec iov[1];
279	ssize_t len;
280	struct cmsghdr *cmsg;
281	struct sockcred *cred = NULL;
282
283	if (pi->buf == NULL) {
284		/* no buffer yet - allocate one */
285		if ((pi->buf = buf_alloc(0)) == NULL) {
286			/* ups - could not get buffer. Read away input
287			 * and drop it */
288			(void)recvfrom(pi->fd, embuf, sizeof(embuf),
289			    0, NULL, NULL);
290			/* return error */
291			return (-1);
292		}
293		pi->buflen = buf_size(0);
294	}
295
296	/* try to get a message */
297	msg.msg_name = pi->peer;
298	msg.msg_namelen = pi->peerlen;
299	msg.msg_iov = iov;
300	msg.msg_iovlen = 1;
301	memset(cbuf, 0, sizeof(cbuf));
302	msg.msg_control = cbuf;
303	msg.msg_controllen = sizeof(cbuf);
304	msg.msg_flags = 0;
305
306	iov[0].iov_base = pi->buf;
307	iov[0].iov_len = pi->buflen;
308
309	len = recvmsg(pi->fd, &msg, 0);
310
311	if (len == -1 || len == 0)
312		/* receive error */
313		return (-1);
314
315	if (msg.msg_flags & MSG_TRUNC) {
316		/* truncated - drop */
317		snmpd_stats.silentDrops++;
318		snmpd_stats.inTooLong++;
319		return (-1);
320	}
321
322	pi->length = (size_t)len;
323
324	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
325	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
326		if (cmsg->cmsg_level == IPPROTO_IP &&
327		    cmsg->cmsg_type == IP_RECVDSTADDR)
328			memcpy(&p->dstaddr, CMSG_DATA(cmsg),
329			    sizeof(struct in_addr));
330		if (cmsg->cmsg_level == SOL_SOCKET &&
331		    cmsg->cmsg_type == SCM_CREDS)
332			cred = (struct sockcred *)(void *)CMSG_DATA(cmsg);
333	}
334
335	if (pi->cred)
336		check_priv_dgram(pi, cred);
337
338	return (0);
339}
340
341/*
342 * Port table
343 */
344int
345op_snmp_port(struct snmp_context *ctx, struct snmp_value *value,
346    u_int sub, u_int iidx, enum snmp_op op)
347{
348	asn_subid_t which = value->var.subs[sub-1];
349	struct udp_port *p;
350	u_int8_t addr[4];
351	u_int32_t port;
352
353	switch (op) {
354
355	  case SNMP_OP_GETNEXT:
356		if ((p = (struct udp_port *)trans_next_port(my_trans,
357		    &value->var, sub)) == NULL)
358			return (SNMP_ERR_NOSUCHNAME);
359		index_append(&value->var, sub, &p->tport.index);
360		break;
361
362	  case SNMP_OP_GET:
363		if ((p = (struct udp_port *)trans_find_port(my_trans,
364		    &value->var, sub)) == NULL)
365			return (SNMP_ERR_NOSUCHNAME);
366		break;
367
368	  case SNMP_OP_SET:
369		p = (struct udp_port *)trans_find_port(my_trans,
370		    &value->var, sub);
371		ctx->scratch->int1 = (p != NULL);
372
373		if (which != LEAF_begemotSnmpdPortStatus)
374			abort();
375		if (!TRUTH_OK(value->v.integer))
376			return (SNMP_ERR_WRONG_VALUE);
377
378		ctx->scratch->int2 = TRUTH_GET(value->v.integer);
379
380		if (ctx->scratch->int2) {
381			/* open an SNMP port */
382			if (p != NULL)
383				/* already open - do nothing */
384				return (SNMP_ERR_NOERROR);
385
386			if (index_decode(&value->var, sub, iidx, addr, &port))
387				return (SNMP_ERR_NO_CREATION);
388			return (udp_open_port(addr, port, &p));
389
390		} else {
391			/* close SNMP port - do in commit */
392		}
393		return (SNMP_ERR_NOERROR);
394
395	  case SNMP_OP_ROLLBACK:
396		p = (struct udp_port *)trans_find_port(my_trans,
397		    &value->var, sub);
398		if (ctx->scratch->int1 == 0) {
399			/* did not exist */
400			if (ctx->scratch->int2 == 1) {
401				/* created */
402				if (p != NULL)
403					udp_close_port(&p->tport);
404			}
405		}
406		return (SNMP_ERR_NOERROR);
407
408	  case SNMP_OP_COMMIT:
409		p = (struct udp_port *)trans_find_port(my_trans,
410		    &value->var, sub);
411		if (ctx->scratch->int1 == 1) {
412			/* did exist */
413			if (ctx->scratch->int2 == 0) {
414				/* delete */
415				if (p != NULL)
416					udp_close_port(&p->tport);
417			}
418		}
419		return (SNMP_ERR_NOERROR);
420
421	  default:
422		abort();
423	}
424
425	/*
426	 * Come here to fetch the value
427	 */
428	switch (which) {
429
430	  case LEAF_begemotSnmpdPortStatus:
431		value->v.integer = 1;
432		break;
433
434	  default:
435		abort();
436	}
437
438	return (SNMP_ERR_NOERROR);
439}
440