trans_udp.c revision 312057 
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 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
221	return (sendto(p->input.fd, buf, len, 0, addr, addrlen));
222}
223
224static void
225check_priv_dgram(struct port_input *pi, struct sockcred *cred)
226{
227
228	/* process explicitly sends credentials */
229	if (cred)
230		pi->priv = (cred->sc_euid == 0);
231	else
232		pi->priv = 0;
233}
234
235/*
236 * Input from a datagram socket.
237 * Each receive should return one datagram.
238 */
239static ssize_t
240recv_dgram(struct port_input *pi, struct in_addr *laddr)
241{
242	u_char embuf[1000];
243	char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
244	    CMSG_SPACE(sizeof(struct in_addr))];
245	struct msghdr msg;
246	struct iovec iov[1];
247	ssize_t len;
248	struct cmsghdr *cmsg;
249	struct sockcred *cred = NULL;
250
251	if (pi->buf == NULL) {
252		/* no buffer yet - allocate one */
253		if ((pi->buf = buf_alloc(0)) == NULL) {
254			/* ups - could not get buffer. Read away input
255			 * and drop it */
256			(void)recvfrom(pi->fd, embuf, sizeof(embuf),
257			    0, NULL, NULL);
258			/* return error */
259			return (-1);
260		}
261		pi->buflen = buf_size(0);
262	}
263
264	/* try to get a message */
265	msg.msg_name = pi->peer;
266	msg.msg_namelen = pi->peerlen;
267	msg.msg_iov = iov;
268	msg.msg_iovlen = 1;
269	memset(cbuf, 0, sizeof(cbuf));
270	msg.msg_control = cbuf;
271	msg.msg_controllen = sizeof(cbuf);
272	msg.msg_flags = 0;
273
274	iov[0].iov_base = pi->buf;
275	iov[0].iov_len = pi->buflen;
276
277	len = recvmsg(pi->fd, &msg, 0);
278
279	if (len == -1 || len == 0)
280		/* receive error */
281		return (-1);
282
283	if (msg.msg_flags & MSG_TRUNC) {
284		/* truncated - drop */
285		snmpd_stats.silentDrops++;
286		snmpd_stats.inTooLong++;
287		return (-1);
288	}
289
290	pi->length = (size_t)len;
291
292	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
293	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
294		if (cmsg->cmsg_level == IPPROTO_IP &&
295		    cmsg->cmsg_type == IP_RECVDSTADDR)
296			memcpy(laddr, CMSG_DATA(cmsg), sizeof(struct in_addr));
297		if (cmsg->cmsg_level == SOL_SOCKET &&
298		    cmsg->cmsg_type == SCM_CREDS)
299			cred = (struct sockcred *)CMSG_DATA(cmsg);
300	}
301
302	if (pi->cred)
303		check_priv_dgram(pi, cred);
304
305	return (0);
306}
307
308/*
309 * Receive something
310 */
311static ssize_t
312udp_recv(struct port_input *pi)
313{
314	struct in_addr *laddr;
315	struct msghdr msg;
316	char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
317	struct cmsghdr *cmsgp;
318	ssize_t ret;
319
320	memset(cbuf, 0, sizeof(cbuf));
321
322	msg.msg_control = cbuf;
323	msg.msg_controllen = sizeof(cbuf);
324
325	cmsgp = CMSG_FIRSTHDR(&msg);
326	cmsgp->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
327	cmsgp->cmsg_level = IPPROTO_IP;
328	cmsgp->cmsg_type = IP_SENDSRCADDR;
329	laddr = (struct in_addr *)CMSG_DATA(cmsgp);
330
331	ret = recv_dgram(pi, laddr);
332
333	if (laddr->s_addr == INADDR_ANY) {
334		msg.msg_control = NULL;
335		msg.msg_controllen = 0;
336	}
337
338	return (ret);
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