trans_udp.c revision 312265 
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 <stdlib.h>
38#include <syslog.h>
39#include <string.h>
40#include <errno.h>
41#include <unistd.h>
42
43#include <netinet/in.h>
44#include <arpa/inet.h>
45
46#include "snmpmod.h"
47#include "snmpd.h"
48#include "trans_udp.h"
49#include "tree.h"
50#include "oid.h"
51
52static int udp_start(void);
53static int udp_stop(int);
54static void udp_close_port(struct tport *);
55static int udp_init_port(struct tport *);
56static ssize_t udp_send(struct tport *, const u_char *, size_t,
57    const struct sockaddr *, size_t);
58static ssize_t udp_recv(struct tport *, struct port_input *);
59
60/* exported */
61const struct transport_def udp_trans = {
62	"udp",
63	OIDX_begemotSnmpdTransUdp,
64	udp_start,
65	udp_stop,
66	udp_close_port,
67	udp_init_port,
68	udp_send,
69	udp_recv
70};
71static struct transport *my_trans;
72
73static int
74udp_start(void)
75{
76	return (trans_register(&udp_trans, &my_trans));
77}
78
79static int
80udp_stop(int force __unused)
81{
82	if (my_trans != NULL)
83		if (trans_unregister(my_trans) != 0)
84			return (SNMP_ERR_GENERR);
85	return (SNMP_ERR_NOERROR);
86}
87
88/*
89 * A UDP port is ready
90 */
91static void
92udp_input(int fd __unused, void *udata)
93{
94	struct udp_port *p = udata;
95
96	p->input.peerlen = sizeof(p->ret);
97	snmpd_input(&p->input, &p->tport);
98}
99
100/*
101 * Create a UDP socket and bind it to the given port
102 */
103static int
104udp_init_port(struct tport *tp)
105{
106	struct udp_port *p = (struct udp_port *)tp;
107	struct sockaddr_in addr;
108	u_int32_t ip;
109	const int on = 1;
110
111	if ((p->input.fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
112		syslog(LOG_ERR, "creating UDP socket: %m");
113		return (SNMP_ERR_RES_UNAVAIL);
114	}
115	ip = (p->addr[0] << 24) | (p->addr[1] << 16) | (p->addr[2] << 8) |
116	    p->addr[3];
117	memset(&addr, 0, sizeof(addr));
118	addr.sin_addr.s_addr = htonl(ip);
119	addr.sin_port = htons(p->port);
120	addr.sin_family = AF_INET;
121	addr.sin_len = sizeof(addr);
122	if (addr.sin_addr.s_addr == INADDR_ANY &&
123	    setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
124	    sizeof(on)) == -1) {
125		syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
126		close(p->input.fd);
127		p->input.fd = -1;
128		return (SNMP_ERR_GENERR);
129	}
130	if (bind(p->input.fd, (struct sockaddr *)&addr, sizeof(addr))) {
131		if (errno == EADDRNOTAVAIL) {
132			close(p->input.fd);
133			p->input.fd = -1;
134			return (SNMP_ERR_INCONS_NAME);
135		}
136		syslog(LOG_ERR, "bind: %s:%u %m", inet_ntoa(addr.sin_addr),
137		    p->port);
138		close(p->input.fd);
139		p->input.fd = -1;
140		return (SNMP_ERR_GENERR);
141	}
142	if ((p->input.id = fd_select(p->input.fd, udp_input,
143	    p, NULL)) == NULL) {
144		close(p->input.fd);
145		p->input.fd = -1;
146		return (SNMP_ERR_GENERR);
147	}
148	return (SNMP_ERR_NOERROR);
149}
150
151/*
152 * Create a new SNMP Port object and start it, if we are not
153 * in initialization mode. The arguments are in host byte order.
154 */
155static int
156udp_open_port(u_int8_t *addr, u_int32_t udp_port, struct udp_port **pp)
157{
158	struct udp_port *port;
159	int err;
160
161	if (udp_port > 0xffff)
162		return (SNMP_ERR_NO_CREATION);
163	if ((port = malloc(sizeof(*port))) == NULL)
164		return (SNMP_ERR_GENERR);
165	memset(port, 0, sizeof(*port));
166
167	/* initialize common part */
168	port->tport.index.len = 5;
169	port->tport.index.subs[0] = addr[0];
170	port->tport.index.subs[1] = addr[1];
171	port->tport.index.subs[2] = addr[2];
172	port->tport.index.subs[3] = addr[3];
173	port->tport.index.subs[4] = udp_port;
174
175	port->addr[0] = addr[0];
176	port->addr[1] = addr[1];
177	port->addr[2] = addr[2];
178	port->addr[3] = addr[3];
179	port->port = udp_port;
180
181	port->input.fd = -1;
182	port->input.id = NULL;
183	port->input.stream = 0;
184	port->input.cred = 0;
185	port->input.peer = (struct sockaddr *)&port->ret;
186	port->input.peerlen = sizeof(port->ret);
187
188	trans_insert_port(my_trans, &port->tport);
189
190	if (community != COMM_INITIALIZE &&
191	    (err = udp_init_port(&port->tport)) != SNMP_ERR_NOERROR) {
192		udp_close_port(&port->tport);
193		return (err);
194	}
195	*pp = port;
196	return (SNMP_ERR_NOERROR);
197}
198
199/*
200 * Close an SNMP port
201 */
202static void
203udp_close_port(struct tport *tp)
204{
205	struct udp_port *port = (struct udp_port *)tp;
206
207	snmpd_input_close(&port->input);
208	trans_remove_port(tp);
209	free(port);
210}
211
212/*
213 * Send something
214 */
215static ssize_t
216udp_send(struct tport *tp, const u_char *buf, size_t len,
217    const struct sockaddr *addr, size_t addrlen)
218{
219	struct udp_port *p = (struct udp_port *)tp;
220	struct cmsghdr *cmsg;
221	struct in_addr *src_addr;
222	struct msghdr msg;
223	char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
224	struct iovec iov;
225
226	iov.iov_base = __DECONST(void*, buf);
227	iov.iov_len = len;
228
229	msg.msg_iov = &iov;
230	msg.msg_iovlen = 1;
231	msg.msg_name = __DECONST(void *, addr);
232	msg.msg_namelen = addrlen;
233	msg.msg_control = cbuf;
234	msg.msg_controllen = sizeof(cbuf);
235
236	cmsg = CMSG_FIRSTHDR(&msg);
237	cmsg->cmsg_level = IPPROTO_IP;
238	cmsg->cmsg_type = IP_SENDSRCADDR;
239	cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
240	src_addr = (struct in_addr *)(void*)CMSG_DATA(cmsg);
241	memcpy(src_addr, &p->recv_addr, sizeof(struct in_addr));
242
243	return (sendmsg(p->input.fd, &msg, 0));
244}
245
246static void
247check_priv_dgram(struct port_input *pi, struct sockcred *cred)
248{
249
250	/* process explicitly sends credentials */
251	if (cred)
252		pi->priv = (cred->sc_euid == 0);
253	else
254		pi->priv = 0;
255}
256
257/*
258 * Input from a datagram socket.
259 * Each receive should return one datagram.
260 */
261static ssize_t
262recv_dgram(struct port_input *pi, struct in_addr *laddr)
263{
264	u_char embuf[1000];
265	char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
266	    CMSG_SPACE(sizeof(struct in_addr))];
267	struct msghdr msg;
268	struct iovec iov[1];
269	ssize_t len;
270	struct cmsghdr *cmsg;
271	struct sockcred *cred = NULL;
272
273	if (pi->buf == NULL) {
274		/* no buffer yet - allocate one */
275		if ((pi->buf = buf_alloc(0)) == NULL) {
276			/* ups - could not get buffer. Read away input
277			 * and drop it */
278			(void)recvfrom(pi->fd, embuf, sizeof(embuf),
279			    0, NULL, NULL);
280			/* return error */
281			return (-1);
282		}
283		pi->buflen = buf_size(0);
284	}
285
286	/* try to get a message */
287	msg.msg_name = pi->peer;
288	msg.msg_namelen = pi->peerlen;
289	msg.msg_iov = iov;
290	msg.msg_iovlen = 1;
291	memset(cbuf, 0, sizeof(cbuf));
292	msg.msg_control = cbuf;
293	msg.msg_controllen = sizeof(cbuf);
294	msg.msg_flags = 0;
295
296	iov[0].iov_base = pi->buf;
297	iov[0].iov_len = pi->buflen;
298
299	len = recvmsg(pi->fd, &msg, 0);
300
301	if (len == -1 || len == 0)
302		/* receive error */
303		return (-1);
304
305	if (msg.msg_flags & MSG_TRUNC) {
306		/* truncated - drop */
307		snmpd_stats.silentDrops++;
308		snmpd_stats.inTooLong++;
309		return (-1);
310	}
311
312	pi->length = (size_t)len;
313
314	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
315	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
316		if (cmsg->cmsg_level == IPPROTO_IP &&
317		    cmsg->cmsg_type == IP_RECVDSTADDR)
318			memcpy(laddr, CMSG_DATA(cmsg), sizeof(struct in_addr));
319		if (cmsg->cmsg_level == SOL_SOCKET &&
320		    cmsg->cmsg_type == SCM_CREDS)
321			cred = (struct sockcred *)CMSG_DATA(cmsg);
322	}
323
324	if (pi->cred)
325		check_priv_dgram(pi, cred);
326
327	return (0);
328}
329
330/*
331 * Receive something
332 */
333static ssize_t
334udp_recv(struct tport *tp, struct port_input *pi)
335{
336	struct udp_port *p = (struct udp_port *)tp;
337	struct in_addr *laddr;
338	struct msghdr msg;
339	char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
340	struct cmsghdr *cmsgp;
341	ssize_t ret;
342
343	memset(cbuf, 0, sizeof(cbuf));
344
345	msg.msg_control = cbuf;
346	msg.msg_controllen = sizeof(cbuf);
347
348	cmsgp = CMSG_FIRSTHDR(&msg);
349	cmsgp->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
350	cmsgp->cmsg_level = IPPROTO_IP;
351	cmsgp->cmsg_type = IP_SENDSRCADDR;
352	laddr = (struct in_addr *)CMSG_DATA(cmsgp);
353
354	ret = recv_dgram(pi, laddr);
355
356	memcpy(&p->recv_addr, laddr, sizeof(struct in_addr));
357
358	if (laddr->s_addr == INADDR_ANY) {
359		msg.msg_control = NULL;
360		msg.msg_controllen = 0;
361	}
362
363	return (ret);
364}
365
366/*
367 * Port table
368 */
369int
370op_snmp_port(struct snmp_context *ctx, struct snmp_value *value,
371    u_int sub, u_int iidx, enum snmp_op op)
372{
373	asn_subid_t which = value->var.subs[sub-1];
374	struct udp_port *p;
375	u_int8_t addr[4];
376	u_int32_t port;
377
378	switch (op) {
379
380	  case SNMP_OP_GETNEXT:
381		if ((p = (struct udp_port *)trans_next_port(my_trans,
382		    &value->var, sub)) == NULL)
383			return (SNMP_ERR_NOSUCHNAME);
384		index_append(&value->var, sub, &p->tport.index);
385		break;
386
387	  case SNMP_OP_GET:
388		if ((p = (struct udp_port *)trans_find_port(my_trans,
389		    &value->var, sub)) == NULL)
390			return (SNMP_ERR_NOSUCHNAME);
391		break;
392
393	  case SNMP_OP_SET:
394		p = (struct udp_port *)trans_find_port(my_trans,
395		    &value->var, sub);
396		ctx->scratch->int1 = (p != NULL);
397
398		if (which != LEAF_begemotSnmpdPortStatus)
399			abort();
400		if (!TRUTH_OK(value->v.integer))
401			return (SNMP_ERR_WRONG_VALUE);
402
403		ctx->scratch->int2 = TRUTH_GET(value->v.integer);
404
405		if (ctx->scratch->int2) {
406			/* open an SNMP port */
407			if (p != NULL)
408				/* already open - do nothing */
409				return (SNMP_ERR_NOERROR);
410
411			if (index_decode(&value->var, sub, iidx, addr, &port))
412				return (SNMP_ERR_NO_CREATION);
413			return (udp_open_port(addr, port, &p));
414
415		} else {
416			/* close SNMP port - do in commit */
417		}
418		return (SNMP_ERR_NOERROR);
419
420	  case SNMP_OP_ROLLBACK:
421		p = (struct udp_port *)trans_find_port(my_trans,
422		    &value->var, sub);
423		if (ctx->scratch->int1 == 0) {
424			/* did not exist */
425			if (ctx->scratch->int2 == 1) {
426				/* created */
427				if (p != NULL)
428					udp_close_port(&p->tport);
429			}
430		}
431		return (SNMP_ERR_NOERROR);
432
433	  case SNMP_OP_COMMIT:
434		p = (struct udp_port *)trans_find_port(my_trans,
435		    &value->var, sub);
436		if (ctx->scratch->int1 == 1) {
437			/* did exist */
438			if (ctx->scratch->int2 == 0) {
439				/* delete */
440				if (p != NULL)
441					udp_close_port(&p->tport);
442			}
443		}
444		return (SNMP_ERR_NOERROR);
445
446	  default:
447		abort();
448	}
449
450	/*
451	 * Come here to fetch the value
452	 */
453	switch (which) {
454
455	  case LEAF_begemotSnmpdPortStatus:
456		value->v.integer = 1;
457		break;
458
459	  default:
460		abort();
461	}
462
463	return (SNMP_ERR_NOERROR);
464}
465