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snmp: added helper functions to encode/decode BITS pseudo type, added define for Counter64 type, minor layout changes

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This commit is contained in:
goldsimon 2015-09-30 17:24:53 +02:00
parent df1f12778f
commit 96847c1199
3 changed files with 103 additions and 12 deletions
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47
src/core/snmp/asn1_dec.c
View File

@ -654,4 +654,51 @@ snmp_asn1_dec_raw(struct pbuf *p, u16_t ofs, u16_t len, u16_t raw_len, u8_t *raw
}
}
/**
* Decodes BITS pseudotype value from ASN.1 OctetString.
*
* @note Because BITS pseudo type is encoded as OCTET STRING, it cannot directly
* be encoded/decoded by the agent. Instead call this function as required from
* get/test/set methods.
*
* @param buf points to a buffer holding the ASN1 octet string
* @param buf_len length of octet string
* @param bit_value decoded Bit value with Bit0 == LSB
* @return ERR_OK if successful, ERR_ARG if bit value contains more than 32 bit
*/
err_t
snmp_asn1_dec_bits(const u8_t *buf, u32_t buf_len, u32_t *bit_value)
{
u8_t b;
u8_t bits_processed = 0;
*bit_value = 0;
while (buf_len > 0) {
/* any bit set in this byte? */
if (*buf != 0x00) {
if (bits_processed >= 32) {
/* accept more than 4 bytes, but only when no bits are set */
return ERR_ARG;
}
b = *buf;
do {
if (b & 0x80) {
*bit_value |= (1 << bits_processed);
}
bits_processed++;
b <<= 1;
}
while ((bits_processed % 8) != 0);
} else {
bits_processed += 8;
}
buf_len--;
buf++;
}
return ERR_OK;
}
#endif /* LWIP_SNMP */

40
src/core/snmp/asn1_enc.c
View File

@ -608,4 +608,44 @@ snmp_asn1_enc_raw(struct pbuf *p, u16_t ofs, u16_t raw_len, const u8_t *raw)
return ERR_ARG;
}
/**
* Encodes BITS pseudotype value into ASN.1 OctetString.
*
* @note Because BITS pseudo type is encoded as OCTET STRING, it cannot directly
* be encoded/decoded by the agent. Instead call this function as required from
* get/test/set methods.
*
* @param buf points to a buffer where the resulting ASN1 octet string is stored to
* @param buf_len max length of the bufffer
* @param bit_value Bit value to encode with Bit0 == LSB
* @return number of bytes used from buffer to store the resulting OctetString
*/
u8_t
snmp_asn1_enc_bits(u8_t *buf, u32_t buf_len, u32_t bit_value)
{
int i = 0;
u8_t len = 0;
u8_t *buf_ptr = (u8_t *)buf;
while ((buf_len > 0) && (bit_value != 0x00)) {
*buf_ptr = 0x00;
i = 8;
while (i > 0) {
if (bit_value & 0x01) {
*buf_ptr |= 0x01;
}
bit_value >>= 1;
*buf_ptr <<= 1;
i--;
}
buf_ptr++;
buf_len--;
len++;
}
return len;
}
#endif /* LWIP_SNMP */

28
src/include/lwip/snmp_asn1.h
View File

@ -53,26 +53,27 @@ extern "C" {
#define SNMP_ASN1_CONSTR (0x20) /* ( 0x20) */
#define SNMP_ASN1_PRIMIT (0) /* (!0x20) */
/* universal tags */
/* universal tags (from ASN.1 spec.) */
#define SNMP_ASN1_INTEG 2
#define SNMP_ASN1_OC_STR 4
#define SNMP_ASN1_NUL 5
#define SNMP_ASN1_OBJ_ID 6
#define SNMP_ASN1_SEQ 16
/* application specific (SNMP) tags */
#define SNMP_ASN1_IPADDR 0 /* octet string size(4) */
#define SNMP_ASN1_COUNTER 1 /* u32_t */
#define SNMP_ASN1_GAUGE 2 /* u32_t */
#define SNMP_ASN1_TIMETICKS 3 /* u32_t */
#define SNMP_ASN1_OPAQUE 4 /* octet string */
/* application specific (SNMP) tags (from SNMPv2-SMI) */
#define SNMP_ASN1_IPADDR 0 /* [APPLICATION 0] IMPLICIT OCTET STRING (SIZE (4)) */
#define SNMP_ASN1_COUNTER 1 /* [APPLICATION 1] IMPLICIT INTEGER (0..4294967295) => u32_t */
#define SNMP_ASN1_GAUGE 2 /* [APPLICATION 2] IMPLICIT INTEGER (0..4294967295) => u32_t */
#define SNMP_ASN1_TIMETICKS 3 /* [APPLICATION 3] IMPLICIT INTEGER (0..4294967295) => u32_t */
#define SNMP_ASN1_OPAQUE 4 /* [APPLICATION 4] IMPLICIT OCTET STRING */
#define SNMP_ASN1_COUNTER64 6 /* [APPLICATION 6] IMPLICIT INTEGER (0..18446744073709551615) */
/* context specific (SNMP) tags */
#define SNMP_ASN1_PDU_GET_REQ 0
/* context specific (SNMP) tags (from SNMP spec. RFC1157) */
#define SNMP_ASN1_PDU_GET_REQ 0
#define SNMP_ASN1_PDU_GET_NEXT_REQ 1
#define SNMP_ASN1_PDU_GET_RESP 2
#define SNMP_ASN1_PDU_SET_REQ 3
#define SNMP_ASN1_PDU_TRAP 4
#define SNMP_ASN1_PDU_GET_RESP 2
#define SNMP_ASN1_PDU_SET_REQ 3
#define SNMP_ASN1_PDU_TRAP 4
err_t snmp_asn1_dec_type(struct pbuf *p, u16_t ofs, u8_t *type);
err_t snmp_asn1_dec_length(struct pbuf *p, u16_t ofs, u8_t *octets_used, u16_t *length);
@ -92,6 +93,9 @@ err_t snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, s32_t v
err_t snmp_asn1_enc_oid(struct pbuf *p, u16_t ofs, u16_t ident_len, const s32_t *ident);
err_t snmp_asn1_enc_raw(struct pbuf *p, u16_t ofs, u16_t raw_len, const u8_t *raw);
err_t snmp_asn1_dec_bits(const u8_t *buf, u32_t buf_len, u32_t *bit_value);
u8_t snmp_asn1_enc_bits(u8_t *buf, u32_t buf_len, u32_t bit_value);
#ifdef __cplusplus
}
#endif