int snmp_msg_write(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;
unsigned char *msg_ptr, *msg_hdr_start, *msg_hdr_end;
size_t msg_hdr_startlen, msg_len;
int res;
if (p == NULL ||
buf == NULL ||
buflen == NULL ||
community == NULL ||
pdu == NULL) {
errno = EINVAL;
return -1;
}
msg_ptr = msg_hdr_start = *buf;
msg_hdr_startlen = *buflen;
asn1_type = (SNMP_ASN1_TYPE_SEQUENCE|SNMP_ASN1_CONSTRUCT);
asn1_len = 0;
res = snmp_asn1_write_header(p, buf, buflen, asn1_type, asn1_len, 0);
if (res < 0) {
return -1;
}
msg_hdr_end = *buf;
asn1_type = (SNMP_ASN1_CLASS_UNIVERSAL|SNMP_ASN1_PRIMITIVE|SNMP_ASN1_TYPE_INTEGER);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type, snmp_version, 0);
if (res < 0) {
return -1;
}
asn1_type = (SNMP_ASN1_CLASS_UNIVERSAL|SNMP_ASN1_PRIMITIVE|SNMP_ASN1_TYPE_OCTETSTRING);
res = snmp_asn1_write_string(p, buf, buflen, asn1_type, community,
community_len);
if (res < 0) {
return -1;
}
if (pdu != NULL) {
res = snmp_pdu_write(p, buf, buflen, pdu, snmp_version);
if (res < 0) {
return -1;
}
}
/* Calculate the full message length, for use later. */
msg_len = (*buf - msg_hdr_start);
/* Having written out the entire message now, we can go back and fill
* in the appropriate length in the header.
*/
asn1_type = (SNMP_ASN1_TYPE_SEQUENCE|SNMP_ASN1_CONSTRUCT);
asn1_len = (*buf - msg_hdr_end);
pr_trace_msg(trace_channel, 18,
"updating SNMP message header to have length %u", asn1_len);
res = snmp_asn1_write_header(p, &msg_hdr_start, &msg_hdr_startlen,
asn1_type, asn1_len, 0);
if (res < 0) {
return -1;
}
/* XXX This is a bit of a hack here. We started with a buflen, and steadily
* decremented that value as we wrote data into the buffer.
*
* However, buflen needs to the amount of data IN the buffer once we return
* the caller, NOT the amount of data REMAINING in the buffer. So we
* cheat here.
*
* We also cheat by resetting buf to point to the start of the message.
*/
*buflen = msg_len;
*buf = msg_ptr;
return 0;
}
int snmp_pdu_write(pool *p, unsigned char **buf, size_t *buflen,
struct snmp_pdu *pdu, long snmp_version) {
unsigned char asn1_type, *pdu_hdr_start, *pdu_hdr_end;
size_t pdu_hdr_startlen;
unsigned int asn1_len;
int flags, res;
pr_trace_msg(trace_channel, 19,
"writing %s PDU (0x%02x)",
snmp_pdu_get_request_type_desc(pdu->request_type), pdu->request_type);
/* 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
* writers to not trace log that wrong invalid ASN.1 type. Makes the
* trace logging confusing and incorrect.
*/
flags = SNMP_ASN1_FL_NO_TRACE_TYPESTR;
asn1_type = pdu->request_type;
asn1_len = 0;
pdu_hdr_start = *buf;
pdu_hdr_startlen = *buflen;
res = snmp_asn1_write_header(p, buf, buflen, asn1_type, asn1_len, flags);
if (res < 0) {
return -1;
}
pdu_hdr_end = *buf;
switch (pdu->request_type) {
case SNMP_PDU_GETBULK:
asn1_type = (SNMP_ASN1_CLASS_UNIVERSAL|SNMP_ASN1_PRIMITIVE|SNMP_ASN1_TYPE_INTEGER);
/* Request ID */
pr_trace_msg(trace_channel, 19,
"writing PDU request ID: %ld", pdu->request_id);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type, pdu->request_id, 0);
if (res < 0) {
return -1;
}
/* Non-repeaters */
pr_trace_msg(trace_channel, 19,
"writing PDU non-repeaters: %ld", pdu->non_repeaters);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type,
pdu->non_repeaters, 0);
if (res < 0) {
return -1;
}
/* Max-repetitions */
pr_trace_msg(trace_channel, 19,
"writing PDU max-repetitions: %ld", pdu->max_repetitions);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type,
pdu->max_repetitions, 0);
if (res < 0) {
return -1;
}
/* XXX write varlist? */
break;
default:
/* "Normal" PDU formatting. */
asn1_type = (SNMP_ASN1_CLASS_UNIVERSAL|SNMP_ASN1_PRIMITIVE|SNMP_ASN1_TYPE_INTEGER);
/* Request ID */
pr_trace_msg(trace_channel, 19,
"writing PDU request ID: %ld", pdu->request_id);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type, pdu->request_id, 0);
if (res < 0) {
return -1;
}
/* Error Status/Code */
pr_trace_msg(trace_channel, 19,
"writing PDU error status/code: %ld", pdu->err_code);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type, pdu->err_code, 0);
if (res < 0) {
return -1;
}
/* Error Index */
pr_trace_msg(trace_channel, 19,
"writing PDU error index: %ld", pdu->err_idx);
res = snmp_asn1_write_int(p, buf, buflen, asn1_type, pdu->err_idx, 0);
if (res < 0) {
return -1;
}
/* Variable bindings list */
pr_trace_msg(trace_channel, 19,
"writing PDU variable binding list: (%u %s)", pdu->varlistlen,
pdu->varlistlen != 1 ? "variables" : "variable");
res = snmp_smi_write_vars(p, buf, buflen, pdu->varlist, snmp_version);
if (res < 0) {
return -1;
}
break;
}
/* Rewrite the PDU header, this time with the length of the entire PDU. */
asn1_type = pdu->request_type;
asn1_len = (*buf - pdu_hdr_end);
pr_trace_msg(trace_channel, 18,
"updating PDU header to have length %u", asn1_len);
res = snmp_asn1_write_header(p, &pdu_hdr_start, &pdu_hdr_startlen, asn1_type,
asn1_len, flags);
if (res < 0) {
return -1;
}
return 0;
}
