pdu.c revision 4f90901ff7a0693b0be018de6dcfff7c6e11d734
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* SNMP PDU and packet transport related routines
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "asn1.h"
#include "pdu.h"
#include "debug.h"
/*
* Static declarations
*/
static int snmp_add_null_vars(snmp_pdu_t *, char *, int, int);
static oid *snmp_oidstr_to_oid(int, char *, int, size_t *);
static uchar_t *snmp_build_pdu(snmp_pdu_t *, uchar_t *, size_t *);
static uchar_t *snmp_build_variable(uchar_t *, size_t *, oid *, size_t,
uchar_t, void *, size_t);
static uchar_t *snmp_parse_pdu(int, uchar_t *, size_t *, snmp_pdu_t *);
static uchar_t *snmp_parse_variable(uchar_t *, size_t *, pdu_varlist_t *);
static void snmp_free_null_vars(pdu_varlist_t *);
static uchar_t *snmp_def_community = (uchar_t *)SNMP_DEF_COMMUNITY;
/*
* Allocates and creates a PDU for the specified SNMP command. Currently
* only SNMP_MSG_GET, SNMP_MSG_GETNEXT and SNMP_MSG_GETBULK are supported
*/
snmp_pdu_t *
snmp_create_pdu(int cmd, int max_reps, char *oidstrs, int n_oids, int row)
{
snmp_pdu_t *pdu;
if ((cmd != SNMP_MSG_GET) && (cmd != SNMP_MSG_GETNEXT) &&
(cmd != SNMP_MSG_GETBULK)) {
return (NULL);
}
pdu = (snmp_pdu_t *)calloc(1, sizeof (snmp_pdu_t));
if (pdu == NULL)
return (NULL);
if (cmd == SNMP_MSG_GET || cmd == SNMP_MSG_GETNEXT) {
pdu->version = SNMP_VERSION_1;
pdu->errstat = 0;
pdu->errindex = 0;
} else if (cmd == SNMP_MSG_GETBULK) {
pdu->version = SNMP_VERSION_2c;
pdu->non_repeaters = 0;
pdu->max_repetitions = max_reps ?
max_reps : SNMP_DEF_MAX_REPETITIONS;
}
pdu->command = cmd;
pdu->reqid = snmp_get_reqid();
pdu->community = snmp_def_community;
pdu->community_len = SNMP_DEF_COMMUNITY_LEN;
if (snmp_add_null_vars(pdu, oidstrs, n_oids, row) < 0) {
free((void *) pdu);
return (NULL);
}
pdu->req_pkt = NULL;
pdu->req_pktsz = 0;
pdu->reply_pkt = NULL;
pdu->reply_pktsz = 0;
return (pdu);
}
/*
* Builds a complete ASN.1 encoded snmp message packet out of the PDU.
* Currently the maximum request packet is limited to SNMP_DEF_PKTBUF_SZ.
* Since we only send SNMP_MSG_GET, SNMP_MSG_GETNEXT and SNMP_MSG_GETBULK,
* as long as the number of bulk oids are not *too* many, we're safe with
* this limit (the typical packet size of a bulk request of 10 vars is
* around 250 bytes).
*/
int
snmp_make_packet(snmp_pdu_t *pdu)
{
uchar_t *buf, *p;
uchar_t *msg_seq_end;
uchar_t id;
size_t bufsz = SNMP_DEF_PKTBUF_SZ;
size_t seqlen;
if ((buf = (uchar_t *)calloc(1, SNMP_DEF_PKTBUF_SZ)) == NULL)
return (-1);
/*
* Let's start with the ASN sequence tag. Set the length
* to 0 initially and fill it up once the message packetizing
* is complete.
*/
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_build_sequence(buf, &bufsz, id, 0)) == NULL) {
free((void *) buf);
return (-1);
}
msg_seq_end = p;
/*
* Store the version
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER;
if ((p = asn_build_int(p, &bufsz, id, pdu->version)) == NULL) {
free((void *) buf);
return (-1);
}
/*
* Store the community string
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR;
p = asn_build_string(p, &bufsz, id, pdu->community, pdu->community_len);
if (p == NULL) {
free((void *) buf);
return (-1);
}
/*
* Build the PDU
*/
if ((p = snmp_build_pdu(pdu, p, &bufsz)) == NULL) {
free((void *) buf);
return (-1);
}
/*
* Complete the message pkt by updating the message sequence length
*/
seqlen = p - msg_seq_end;
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
(void) asn_build_sequence(buf, NULL, id, seqlen);
/*
* Calculate packet size and return
*/
pdu->req_pkt = buf;
pdu->req_pktsz = p - buf;
return (0);
}
/*
* Makes a PDU out of a reply packet. The reply message is parsed
* and if the reqid of the incoming packet does not match the reqid
* we're waiting for, an error is returned. The PDU is allocated
* inside this routine and must be freed by the caller once it is no
* longer needed.
*/
snmp_pdu_t *
snmp_parse_reply(int reqid, uchar_t *reply_pkt, size_t reply_pktsz)
{
snmp_pdu_t *reply_pdu;
uchar_t *p;
size_t msgsz = reply_pktsz;
uchar_t exp_id;
reply_pdu = (snmp_pdu_t *)calloc(1, sizeof (snmp_pdu_t));
if (reply_pdu == NULL)
return (NULL);
/*
* Try to parse the ASN sequence out of the beginning of the reply
* packet. If we don't find a sequence at the beginning, something's
* wrong.
*/
exp_id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_parse_sequence(reply_pkt, &msgsz, exp_id)) == NULL) {
snmp_free_pdu(reply_pdu);
return (NULL);
}
/*
* Now try to parse the version out of the packet
*/
if ((p = asn_parse_int(p, &msgsz, &reply_pdu->version)) == NULL) {
snmp_free_pdu(reply_pdu);
return (NULL);
}
if ((reply_pdu->version != SNMP_VERSION_1) &&
(reply_pdu->version != SNMP_VERSION_2c)) {
snmp_free_pdu(reply_pdu);
return (NULL);
}
/*
* Parse the community string (space allocated by asn_parse_string)
*/
p = asn_parse_string(p, &msgsz, &reply_pdu->community,
&reply_pdu->community_len);
if (p == NULL) {
snmp_free_pdu(reply_pdu);
return (NULL);
}
/*
* Parse the PDU part of the message
*/
if ((p = snmp_parse_pdu(reqid, p, &msgsz, reply_pdu)) == NULL) {
snmp_free_pdu(reply_pdu);
return (NULL);
}
return (reply_pdu);
}
/*
* Convert the OID strings into the standard PDU oid form (sequence of
* integer subids) and add them to the PDU's variable list. Note that
* this is used only for preparing the request messages (GET, GETNEXT
* and GETBULK), so the values of the variables are always null.
*/
static int
snmp_add_null_vars(snmp_pdu_t *pdu, char *oidstrs, int n_oids, int row)
{
pdu_varlist_t *vp, *prev;
pdu_varlist_t *varblock_p = NULL;
char *p;
int i;
prev = NULL;
p = oidstrs;
for (i = 0; i < n_oids; i++) {
if ((vp = calloc(1, sizeof (pdu_varlist_t))) == NULL) {
snmp_free_null_vars(varblock_p);
return (-1);
} else if (i == 0) {
varblock_p = vp;
} else {
prev->nextvar = vp;
}
vp->name = snmp_oidstr_to_oid(pdu->command,
p, row, &vp->name_len);
if (vp->name == NULL) {
snmp_free_null_vars(varblock_p);
return (-1);
}
vp->val.str = NULL;
vp->val_len = 0;
vp->type = ASN_NULL;
vp->nextvar = NULL;
LOGVAR(TAG_NULL_VAR, vp);
prev = vp;
p += strlen(p) + 1;
}
/*
* append the varlist to the PDU
*/
if (pdu->vars == NULL)
pdu->vars = varblock_p;
else {
for (vp = pdu->vars; vp->nextvar; vp = vp->nextvar)
;
vp->nextvar = varblock_p;
}
return (0);
}
/*
* Some assumptions are in place here to eliminate unnecessary complexity.
* All OID strings passed are assumed to be in the numeric string form, have
* no leading/trailing '.' or spaces. Since PICL plugin is currently the
* only customer, this is quite reasonable.
*/
static oid *
snmp_oidstr_to_oid(int cmd, char *oidstr, int row, size_t *n_subids)
{
int i, count;
char *p, *q;
char *oidstr_dup;
oid *objid;
if ((oidstr == NULL) || (n_subids == NULL))
return (NULL);
for (count = 1, p = oidstr; p; count++, p++) {
if ((p = strchr(p, '.')) == NULL)
break;
}
/*
* Add one more to count for 'row'. Need special processing
* for SNMP_MSG_GETNEXT and SNMP_MSG_GETBULK requests; see
* comment below.
*/
if ((cmd == SNMP_MSG_GET) || (cmd == SNMP_MSG_GETBULK && row > 0) ||
(cmd == SNMP_MSG_GETNEXT && row >= 0)) {
count++;
}
if ((oidstr_dup = strdup(oidstr)) == NULL)
return (NULL);
objid = (oid *) calloc(count, sizeof (oid));
if (objid == NULL) {
free((void *) p);
return (NULL);
}
p = oidstr_dup;
for (i = 0; i < count - 1; i++) {
if (q = strchr(p, '.'))
*q = 0;
objid[i] = (oid) strtoul(p, NULL, 10);
p = q + 1;
}
/*
* For SNMP_MSG_GET, the leaf subid will simply be the row#.
*
* For SNMP_MSG_GETBULK, if the row# passed is greater than 0,
* we pass 'row-1' as the leaf subid, to include the item that
* is of interest to us. If the row# is less than or equal to 0,
* we will simply ignore it and pass only the prefix part of the
* oidstr. For this case, our count would have been 1 less than
* usual, and we are yet to save the last subid.
*
* For SNMP_MSG_GETNEXT, if the row# passed is less than 0,
* we'll simply ignore it and pass only the prefix part of the
* oidstr. For this case, our count would have been 1 less than
* usual, and we are yet to save the last subid. If the row#
* passed is greater than or equal to 0, we'll simply pass it
* verbatim, as the leaf subid.
*/
switch (cmd) {
case SNMP_MSG_GET:
objid[i] = (oid) row;
break;
case SNMP_MSG_GETBULK:
if (row > 0)
objid[i] = (oid) (row - 1);
else
objid[i] = (oid) strtoul(p, NULL, 10);
break;
case SNMP_MSG_GETNEXT:
if (row < 0)
objid[i] = (oid) strtoul(p, NULL, 10);
else
objid[i] = (oid) row;
break;
}
*n_subids = count;
free((void *) oidstr_dup);
return (objid);
}
/*
* Builds the PDU part of the snmp message packet.
*/
static uchar_t *
snmp_build_pdu(snmp_pdu_t *pdu, uchar_t *buf, size_t *bufsz_p)
{
uchar_t *p;
uchar_t *pdu_seq_begin, *pdu_seq_end;
uchar_t *varlist_seq_begin, *varlist_seq_end;
uchar_t id;
size_t seqlen;
pdu_varlist_t *vp;
/*
* Build ASN sequence for the PDU command (length will be
* updated later once the entire command is completely formed)
*/
pdu_seq_begin = buf;
p = asn_build_sequence(buf, bufsz_p, (uchar_t)pdu->command, 0);
if (p == NULL)
return (NULL);
pdu_seq_end = p;
/*
* Build the request id
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER;
if ((p = asn_build_int(p, bufsz_p, id, pdu->reqid)) == NULL)
return (NULL);
/*
* Build the non-repeaters and max-repetitions for SNMP_MSG_GETBULK
* (same as error status and error index for other message types)
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER;
if ((p = asn_build_int(p, bufsz_p, id, pdu->non_repeaters)) == NULL)
return (NULL);
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER;
if ((p = asn_build_int(p, bufsz_p, id, pdu->max_repetitions)) == NULL)
return (NULL);
/*
* Build ASN sequence for the variables list (update length
* after building the varlist)
*/
varlist_seq_begin = p;
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_build_sequence(p, bufsz_p, id, 0)) == NULL)
return (NULL);
varlist_seq_end = p;
/*
* Build the variables list
*/
for (vp = pdu->vars; vp; vp = vp->nextvar) {
p = snmp_build_variable(p, bufsz_p, vp->name, vp->name_len,
vp->type, vp->val.str, vp->val_len);
if (p == NULL)
return (NULL);
}
/*
* Now update the varlist sequence length
*/
seqlen = p - varlist_seq_end;
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
(void) asn_build_sequence(varlist_seq_begin, NULL, id, seqlen);
/*
* And finally, update the length for the PDU sequence
*/
seqlen = p - pdu_seq_end;
(void) asn_build_sequence(pdu_seq_begin, NULL, (uchar_t)pdu->command,
seqlen);
return (p);
}
/*
* Builds an object variable into the snmp message packet. Although the
* code is here to build variables of basic types such as integer, object id
* and strings, the only type of variable we ever send via snmp request
* messages is the ASN_NULL type.
*/
static uchar_t *
snmp_build_variable(uchar_t *buf, size_t *bufsz_p, oid *name, size_t name_len,
uchar_t val_type, void *val, size_t val_len)
{
uchar_t *p, *varseq_end;
size_t seqlen;
uchar_t id;
/*
* Each variable binding is in turn defined as a 'SEQUENCE of' by
* the SNMP PDU format, so we'll prepare the sequence and fill up
* the length later. Sigh!
*/
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_build_sequence(buf, bufsz_p, id, 0)) == NULL)
return (NULL);
varseq_end = p;
/*
* Build the object id
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OBJECT_ID;
if ((p = asn_build_objid(p, bufsz_p, id, name, name_len)) == NULL)
return (NULL);
/*
* Currently we only ever build ASN_NULL vars while sending requests,
* since we support only SNMP_MSG_GET, SNMP_MSG_GETNEXT and
* SNMP_MSG_GETBULK.
*/
id = ASN_UNIVERSAL | ASN_PRIMITIVE | val_type;
switch (val_type) {
case ASN_INTEGER:
p = asn_build_int(p, bufsz_p, id, *((int *)val));
if (p == NULL)
return (NULL);
break;
case ASN_OBJECT_ID:
p = asn_build_objid(p, bufsz_p, id, val,
val_len / sizeof (oid));
if (p == NULL)
return (NULL);
break;
case ASN_OCTET_STR:
p = asn_build_string(p, bufsz_p, id, (uchar_t *)val, val_len);
if (p == NULL)
return (NULL);
break;
case ASN_NULL:
if ((p = asn_build_null(p, bufsz_p, id)) == NULL)
return (NULL);
break;
default:
return (NULL);
}
/*
* Rebuild the variable sequence length
*/
seqlen = p - varseq_end;
id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
(void) asn_build_sequence(buf, NULL, id, seqlen);
return (p);
}
/*
* Parse the PDU portion of the incoming snmp message into the reply_pdu.
* Space for all structure members are allocated as needed and must be freed
* by the caller when these are no longer needed.
*/
static uchar_t *
snmp_parse_pdu(int reqid, uchar_t *msg, size_t *msgsz_p, snmp_pdu_t *reply_pdu)
{
uchar_t *p;
uchar_t id, exp_id;
pdu_varlist_t *newvp, *vp = NULL;
/*
* Parse the PDU header out of the message
*/
if ((p = asn_parse_header(msg, msgsz_p, &id)) == NULL)
return (NULL);
if (id != SNMP_MSG_RESPONSE && id != SNMP_MSG_REPORT)
return (NULL);
reply_pdu->command = (int)id;
/*
* Parse the request id and verify that this is the response
* we're expecting.
*/
if ((p = asn_parse_int(p, msgsz_p, &reply_pdu->reqid)) == NULL)
return (NULL);
if (reply_pdu->reqid != reqid)
return (NULL);
/*
* Parse the error-status and error-index values
*/
if ((p = asn_parse_int(p, msgsz_p, &reply_pdu->errstat)) == NULL)
return (NULL);
if ((p = asn_parse_int(p, msgsz_p, &reply_pdu->errindex)) == NULL)
return (NULL);
/*
* Parse the header for the variables list sequence.
*/
exp_id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_parse_sequence(p, msgsz_p, exp_id)) == NULL)
return (NULL);
while (((int)*msgsz_p) > 0) {
if ((newvp = calloc(1, sizeof (pdu_varlist_t))) == NULL)
return (NULL);
if (vp == NULL)
reply_pdu->vars = newvp;
else
vp->nextvar = newvp;
vp = newvp;
if ((p = snmp_parse_variable(p, msgsz_p, vp)) == NULL)
return (NULL);
LOGVAR(TAG_RESPONSE_VAR, vp);
}
return (p);
}
/*
* Allocate and parse the next variable into the varlist
*/
static uchar_t *
snmp_parse_variable(uchar_t *msg, size_t *msgsz_p, pdu_varlist_t *vp)
{
uchar_t *p;
uchar_t exp_id;
/*
* Parse this variable's sequence
*/
exp_id = ASN_UNIVERSAL | ASN_CONSTRUCTOR | ASN_SEQUENCE;
if ((p = asn_parse_sequence(msg, msgsz_p, exp_id)) == NULL)
return (NULL);
/*
* Parse the variable's object identifier
*/
p = asn_parse_objid(p, msgsz_p, &vp->name, &vp->name_len);
if (p == NULL)
return (NULL);
/*
* Parse the object's value
*/
if ((p = asn_parse_objval(p, msgsz_p, vp)) == NULL)
return (NULL);
return (p);
}
void
snmp_free_pdu(snmp_pdu_t *pdu)
{
pdu_varlist_t *vp, *nxt;
if (pdu) {
if ((pdu->community) && (pdu->community != snmp_def_community))
free((void *) pdu->community);
for (vp = pdu->vars; vp; vp = nxt) {
nxt = vp->nextvar;
if (vp->name)
free((void *) vp->name);
if (vp->val.str)
free((void *) vp->val.str);
free((void *) vp);
}
if (pdu->req_pkt)
free((void *) pdu->req_pkt);
if (pdu->reply_pkt)
free((void *) pdu->reply_pkt);
free((void *) pdu);
}
}
static void
snmp_free_null_vars(pdu_varlist_t *varblock_p)
{
pdu_varlist_t *vp, *nxt;
for (vp = varblock_p; vp; vp = nxt) {
nxt = vp->nextvar;
if (vp->name)
free(vp->name);
free(vp);
}
}