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Commit 78e85350 authored by Adam Wujek's avatar Adam Wujek 💬
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lib/snmp: return response with error when oid not found 

Signed-off-by: Adam Wujek's avatarAdam Wujek <adam.wujek@cern.ch>
parent 1d3a29bb
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Showing with 41 additions and 6 deletions
lib/snmp.c
View file @ 78e85350
......@@ -32,6 +32,16 @@
#define ASN_UNSIGNED (ASN_APPLICATION | 2) /* RFC 1902 - same as GAUGE */
#define ASN_TIMETICKS (ASN_APPLICATION | 3)
#define ASN_COUNTER64 (ASN_APPLICATION | 6)
/*
* (error codes from net-snmp's snmp.h)
* Error codes (the value of the field error-status in PDUs)
*/
#define SNMP_ERR_NOERROR (0)
#define SNMP_ERR_TOOBIG (1)
#define SNMP_ERR_NOSUCHNAME (2)
#define SNMP_ERR_BADVALUE (3)
#define SNMP_ERR_READONLY (4)
#define SNMP_ERR_GENERR (5)
#define SNMP_GET 0xA0
#define SNMP_GET_NEXT 0xA1
......@@ -249,7 +259,7 @@ static struct snmp_oid oid_array[] = {
* A0 1C get request of 0x1c
* 02 04 27 05 36 A9 int of 4: request ID
* 02 01 00 int of 1: error
* 02 01 00 int of 1: error
* 02 01 00 int of 1: error index
* 30 0E sequence of 0x0e
* 30 0C sequence of 0x0c
* 06 08 2B 06 01 02 01 01 05 00 oid of 8: .1.3.6.1.2.1.1.5.0
......@@ -278,14 +288,22 @@ static struct snmp_oid oid_array[] = {
#define BYTE_SIZE 0xff
#define BYTE_IGNORE 0xfe
#define BYTE_PDU 0xfd
#define BYTE_ERROR 0xfc
#define BYTE_ERROR_INDEX 0xfb
/* indexes of bytes in snmp packet */
#define BYTE_PACKET_SIZE_i 1
#define BYTE_PDU_i 13
#define BYTE_ERROR_i 23
#define BYTE_ERROR_INDEX_i 26
static uint8_t match_array[] = {
0x30, BYTE_SIZE,
0x02, 0x01, 0x00,
0x04, 0x06, 0x70, 0x75, 0x62, 0x6C, 0x69, 0x63,
BYTE_PDU, BYTE_SIZE,
0x02, 0x04, BYTE_IGNORE, BYTE_IGNORE, BYTE_IGNORE, BYTE_IGNORE,
0x02, 0x01, 0x00,
0x02, 0x01, 0x00,
0x02, 0x01, BYTE_ERROR,
0x02, 0x01, BYTE_ERROR_INDEX,
0x30, BYTE_SIZE,
0x30, BYTE_SIZE,
0x06, BYTE_IGNORE, /* oid follows */
......@@ -300,6 +318,19 @@ static void print_oid_verbose(uint8_t *oid, int len) {
snmp_verbose(".%d", *(oid + i));
}
/* prepare packet to return error, leave the rest of packet as it was */
static uint8_t snmp_prepare_error(uint8_t *buf, uint8_t error)
{
uint8_t ret_size;
buf[BYTE_PDU_i] = SNMP_GET_RESPONSE;
buf[BYTE_ERROR_i] = error;
buf[BYTE_ERROR_INDEX_i] = 1;
ret_size = buf[BYTE_PACKET_SIZE_i] + 2;
snmp_verbose("%s: error returning %i bytes\n", __func__, ret_size);
return ret_size;
}
/* And, now, work out your generic frame responder... */
static int snmp_respond(uint8_t *buf)
{
......@@ -313,6 +344,8 @@ static int snmp_respond(uint8_t *buf)
switch (match_array[i]) {
case BYTE_SIZE:
case BYTE_IGNORE:
case BYTE_ERROR:
case BYTE_ERROR_INDEX:
continue;
case BYTE_PDU:
if (buf[i] != SNMP_GET && buf[i] != SNMP_GET_NEXT)
......@@ -333,14 +366,16 @@ static int snmp_respond(uint8_t *buf)
if (oid->oid_len == incoming_oid_len &&
!memcmp(oid->oid_match, newbuf, oid->oid_len))
break;
if (!oid->oid_len)
return -1;
if (!oid->oid_len) {
snmp_verbose("%s: OID not found!\n", __func__);
return snmp_prepare_error(buf, SNMP_ERR_NOSUCHNAME);
}
if (snmp_mode == SNMP_GET_NEXT) {
/* for SNMP_GET_NEXT go to next OID */
oid++;
if (!oid->oid_len) {
/* we got request with last available OID */
return -1;
return snmp_prepare_error(buf, SNMP_ERR_NOSUCHNAME);
}
memcpy(newbuf, oid->oid_match, oid->oid_len);
/* update OID len, since it might be different */
......
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