int snmp_msg_read(pool *p, unsigned char **buf, size_t *buflen,
char **community, unsigned int *community_len, long *snmp_version,
struct snmp_pdu **pdu) {
unsigned char asn1_type;
unsigned int asn1_len;
int res;
res = snmp_asn1_read_header(p, buf, buflen, &asn1_type, &asn1_len, 0);
if (res < 0) {
return -1;
}
if (asn1_type != (SNMP_ASN1_TYPE_SEQUENCE|SNMP_ASN1_CONSTRUCT)) {
pr_trace_msg(trace_channel, 3,
"unable to read SNMP message (tag '%s')",
snmp_asn1_get_tagstr(p, asn1_type));
errno = EINVAL;
return -1;
}
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type, snmp_version, 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 17,
"read SNMP message for %s", snmp_msg_get_versionstr(*snmp_version));
/* XXX Don't support SNMPv3 yet. */
if (*snmp_version != SNMP_PROTOCOL_VERSION_1 &&
*snmp_version != SNMP_PROTOCOL_VERSION_2) {
(void) pr_log_writefile(snmp_logfd, MOD_SNMP_VERSION,
"%s messages not currently supported, dropping packet",
snmp_msg_get_versionstr(*snmp_version));
res = snmp_db_incr_value(p, SNMP_DB_SNMP_F_PKTS_DROPPED_TOTAL, 1);
if (res < 0) {
(void) pr_log_writefile(snmp_logfd, MOD_SNMP_VERSION,
"error incrementing snmp.packetsDroppedTotal: %s", strerror(errno));
}
errno = ENOSYS;
return -1;
}
res = snmp_asn1_read_string(p, buf, buflen, &asn1_type, community,
community_len);
if (res < 0) {
return -1;
}
/* Check that asn1_type is a UNIVERSTAL/PRIMITIVE/OCTETSTRING. */
if (!(asn1_type == (SNMP_ASN1_CLASS_UNIVERSAL|SNMP_ASN1_PRIMITIVE|SNMP_ASN1_TYPE_OCTETSTRING))) {
pr_trace_msg(trace_channel, 3,
"unable to read OCTET_STRING (received type '%s')",
snmp_asn1_get_tagstr(p, asn1_type));
errno = EINVAL;
return -1;
}
pr_trace_msg(trace_channel, 17,
"read %s message: community = '%s'",
snmp_msg_get_versionstr(*snmp_version), *community);
res = snmp_pdu_read(p, buf, buflen, pdu, *snmp_version);
if (res < 0) {
return -1;
}
return 0;
}
int snmp_pdu_read(pool *p, unsigned char **buf, size_t *buflen,
struct snmp_pdu **pdu, long snmp_version) {
unsigned char asn1_type;
unsigned int asn1_len;
int flags, res;
/* Since the "type" in this header is the PDU request type, the trace logging
* of the ASN.1 type will be wrong. That being the case, simply tell the
* readers to not trace log that wrong invalid ASN.1 type. Makes the
* trace logging confusing and incorrect.
*/
flags = SNMP_ASN1_FL_NO_TRACE_TYPESTR;
res = snmp_asn1_read_header(p, buf, buflen, &asn1_type, &asn1_len, flags);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read in PDU (0x%02x), length %u bytes", asn1_type, asn1_len);
*pdu = snmp_pdu_create(p, asn1_type);
switch (asn1_type) {
case SNMP_PDU_RESPONSE:
case SNMP_PDU_TRAP_V1:
case SNMP_PDU_TRAP_V2:
case SNMP_PDU_INFORM:
case SNMP_PDU_REPORT:
pr_trace_msg(trace_channel, 1,
"handling '%s' PDU not currently supported",
snmp_pdu_get_request_type_desc((*pdu)->request_type));
errno = ENOSYS;
return -1;
case SNMP_PDU_GETBULK:
/* Request ID */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->request_id), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU request ID: %ld", (*pdu)->request_id);
/* Non-repeaters */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->non_repeaters), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU non-repeaters: %ld", (*pdu)->non_repeaters);
/* As per RFC1905, if non_repeaters is negative, it is set to zero. */
if ((*pdu)->non_repeaters < 0) {
(*pdu)->non_repeaters = 0;
}
/* Max-repetitions */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->max_repetitions), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU max-repetitions: %ld", (*pdu)->max_repetitions);
/* As per RFC1905, if max_repetitions is negative, it is set to zero. */
if ((*pdu)->max_repetitions < 0) {
(*pdu)->max_repetitions = 0;
}
break;
default:
/* Request ID */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->request_id), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU request ID: %ld", (*pdu)->request_id);
/* Error Status/Code */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->err_code), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU error status/code: %ld", (*pdu)->err_code);
/* XXX What if err_code is non-zero? */
/* Error Index */
res = snmp_asn1_read_int(p, buf, buflen, &asn1_type,
&((*pdu)->err_idx), 0);
if (res < 0) {
return -1;
}
pr_trace_msg(trace_channel, 19,
"read PDU error index: %ld", (*pdu)->err_idx);
/* XXX What if err_idx is non-zero? */
break;
}
res = snmp_smi_read_vars(p, buf, buflen, &((*pdu)->varlist), snmp_version);
if (res < 0) {
return -1;
}
(*pdu)->varlistlen = res;
pr_trace_msg(trace_channel, 17,
"read %d %s from %s message", res,
res != 1 ? "variables" : "variable",
snmp_msg_get_versionstr(snmp_version));
return 0;
}
