--- /dev/null
+/**
+ * @file
+ * Abstract Syntax Notation One (ISO 8824, 8825) encoding
+ *
+ * @todo not optimised (yet), favor correctness over speed, favor speed over size
+ */
+
+/*
+ * Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * Author: Christiaan Simons <christiaan.simons@axon.tv>
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/snmp_asn1.h"
+
+/**
+ * Returns octet count for length.
+ *
+ * @param length
+ * @param octets_needed points to the return value
+ */
+void
+snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
+{
+ if (length < 0x80U)
+ {
+ *octets_needed = 1;
+ }
+ else if (length < 0x100U)
+ {
+ *octets_needed = 2;
+ }
+ else
+ {
+ *octets_needed = 3;
+ }
+}
+
+/**
+ * Returns octet count for an u32_t.
+ *
+ * @param value
+ * @param octets_needed points to the return value
+ *
+ * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
+ * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
+ * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
+ */
+void
+snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
+{
+ if (value < 0x80UL)
+ {
+ *octets_needed = 1;
+ }
+ else if (value < 0x8000UL)
+ {
+ *octets_needed = 2;
+ }
+ else if (value < 0x800000UL)
+ {
+ *octets_needed = 3;
+ }
+ else if (value < 0x80000000UL)
+ {
+ *octets_needed = 4;
+ }
+ else
+ {
+ *octets_needed = 5;
+ }
+}
+
+/**
+ * Returns octet count for an s32_t.
+ *
+ * @param value
+ * @param octets_needed points to the return value
+ *
+ * @note ASN coded integers are _always_ signed.
+ */
+void
+snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
+{
+ if (value < 0)
+ {
+ value = ~value;
+ }
+ if (value < 0x80L)
+ {
+ *octets_needed = 1;
+ }
+ else if (value < 0x8000L)
+ {
+ *octets_needed = 2;
+ }
+ else if (value < 0x800000L)
+ {
+ *octets_needed = 3;
+ }
+ else
+ {
+ *octets_needed = 4;
+ }
+}
+
+/**
+ * Returns octet count for an object identifier.
+ *
+ * @param ident_len object identifier array length
+ * @param ident points to object identifier array
+ * @param octets_needed points to the return value
+ */
+void
+snmp_asn1_enc_oid_cnt(u8_t ident_len, s32_t *ident, u16_t *octets_needed)
+{
+ s32_t sub_id;
+ u8_t cnt;
+
+ cnt = 0;
+ if (ident_len > 1)
+ {
+ /* compressed prefix in one octet */
+ cnt++;
+ ident_len -= 2;
+ ident += 2;
+ }
+ while(ident_len > 0)
+ {
+ ident_len--;
+ sub_id = *ident;
+
+ sub_id >>= 7;
+ cnt++;
+ while(sub_id > 0)
+ {
+ sub_id >>= 7;
+ cnt++;
+ }
+ ident++;
+ }
+ *octets_needed = cnt;
+}
+
+/**
+ * Encodes ASN type field into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode value into
+ * @param ofs points to the offset within the pbuf chain
+ * @param type input ASN1 type
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ */
+err_t
+snmp_asn1_enc_type(struct pbuf *p, u16_t ofs, u8_t type)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+ *msg_ptr = type;
+ return ERR_OK;
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+/**
+ * Encodes host order length field into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode length into
+ * @param ofs points to the offset within the pbuf chain
+ * @param length is the host order length to be encoded
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ */
+err_t
+snmp_asn1_enc_length(struct pbuf *p, u16_t ofs, u16_t length)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+
+ if (length < 0x80)
+ {
+ *msg_ptr = length;
+ return ERR_OK;
+ }
+ else if (length < 0x100)
+ {
+ *msg_ptr = 0x81;
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ *msg_ptr = length;
+ return ERR_OK;
+ }
+ else
+ {
+ u8_t i;
+
+ /* length >= 0x100 && length <= 0xFFFF */
+ *msg_ptr = 0x82;
+ i = 2;
+ while (i > 0)
+ {
+ i--;
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ if (i == 0)
+ {
+ /* least significant length octet */
+ *msg_ptr = length;
+ }
+ else
+ {
+ /* most significant length octet */
+ *msg_ptr = length >> 8;
+ }
+ }
+ return ERR_OK;
+ }
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+/**
+ * Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode value into
+ * @param ofs points to the offset within the pbuf chain
+ * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
+ * @param value is the host order u32_t value to be encoded
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ *
+ * @see snmp_asn1_enc_u32t_cnt()
+ */
+err_t
+snmp_asn1_enc_u32t(struct pbuf *p, u16_t ofs, u8_t octets_needed, u32_t value)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+
+ if (octets_needed == 5)
+ {
+ /* not enough bits in 'value' add leading 0x00 */
+ octets_needed--;
+ *msg_ptr = 0x00;
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ while (octets_needed > 1)
+ {
+ octets_needed--;
+ *msg_ptr = value >> (octets_needed << 3);
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ /* (only) one least significant octet */
+ *msg_ptr = value;
+ return ERR_OK;
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+/**
+ * Encodes s32_t integer into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode value into
+ * @param ofs points to the offset within the pbuf chain
+ * @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
+ * @param value is the host order s32_t value to be encoded
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ *
+ * @see snmp_asn1_enc_s32t_cnt()
+ */
+err_t
+snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u8_t octets_needed, s32_t value)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+
+ while (octets_needed > 1)
+ {
+ octets_needed--;
+ *msg_ptr = value >> (octets_needed << 3);
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ /* (only) one least significant octet */
+ *msg_ptr = value;
+ return ERR_OK;
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+/**
+ * Encodes object identifier into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode oid into
+ * @param ofs points to the offset within the pbuf chain
+ * @param ident_len object identifier array length
+ * @param ident points to object identifier array
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ */
+err_t
+snmp_asn1_enc_oid(struct pbuf *p, u16_t ofs, u8_t ident_len, s32_t *ident)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+
+ if (ident_len > 1)
+ {
+ if ((ident[0] == 1) && (ident[1] == 3))
+ {
+ /* compressed (most common) prefix .iso.org */
+ *msg_ptr = 0x2b;
+ }
+ else
+ {
+ /* calculate prefix */
+ *msg_ptr = (ident[0] * 40) + ident[1];
+ }
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ ident_len -= 2;
+ ident += 2;
+ }
+ else
+ {
+/* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
+ /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
+ return ERR_ARG;
+ }
+ while (ident_len > 0)
+ {
+ s32_t sub_id;
+ u8_t shift, tail;
+
+ ident_len--;
+ sub_id = *ident;
+ tail = 0;
+ shift = 28;
+ while(shift > 0)
+ {
+ u8_t code;
+
+ code = sub_id >> shift;
+ if ((code != 0) || (tail != 0))
+ {
+ tail = 1;
+ *msg_ptr = code | 0x80;
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ shift -= 7;
+ }
+ *msg_ptr = (u8_t)sub_id & 0x7F;
+ if (ident_len > 0)
+ {
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ /* proceed to next sub-identifier */
+ ident++;
+ }
+ return ERR_OK;
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+/**
+ * Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
+ *
+ * @param p points to output pbuf to encode raw data into
+ * @param ofs points to the offset within the pbuf chain
+ * @param raw_len raw data length
+ * @param raw points raw data
+ * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
+ */
+err_t
+snmp_asn1_enc_raw(struct pbuf *p, u16_t ofs, u8_t raw_len, u8_t *raw)
+{
+ u16_t plen, base;
+ u8_t *msg_ptr;
+
+ plen = 0;
+ while (p != NULL)
+ {
+ base = plen;
+ plen += p->len;
+ if (ofs < plen)
+ {
+ msg_ptr = p->payload;
+ msg_ptr += ofs - base;
+
+ while (raw_len > 1)
+ {
+ /* copy raw_len - 1 octets */
+ raw_len--;
+ *msg_ptr = *raw;
+ raw++;
+ ofs += 1;
+ if (ofs >= plen)
+ {
+ /* next octet in next pbuf */
+ p = p->next;
+ if (p == NULL) { return ERR_ARG; }
+ msg_ptr = p->payload;
+ plen += p->len;
+ }
+ else
+ {
+ /* next octet in same pbuf */
+ msg_ptr++;
+ }
+ }
+ if (raw_len > 0)
+ {
+ /* copy last or single octet */
+ *msg_ptr = *raw;
+ }
+ return ERR_OK;
+ }
+ p = p->next;
+ }
+ /* p == NULL, ofs >= plen */
+ return ERR_ARG;
+}
+
+#endif /* LWIP_SNMP */
