/**
 * @file
 * SNMP Agent message handling structures.
 */

/*
 * 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>
 */

#ifndef __LWIP_SNMP_MSG_H__
#define __LWIP_SNMP_MSG_H__

#include "lwip/opt.h"
#include "lwip/snmp.h"
#include "lwip/snmp_structs.h"

#if SNMP_PRIVATE_MIB
#include "private_mib.h"
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* The listen port of the SNMP agent. Clients have to make their requests to
   this port. Most standard clients won't work if you change this! */
#ifndef SNMP_IN_PORT
#define SNMP_IN_PORT 161
#endif
/* The remote port the SNMP agent sends traps to. Most standard trap sinks won't
   work if you change this! */
#ifndef SNMP_TRAP_PORT
#define SNMP_TRAP_PORT 162
#endif

#define SNMP_ES_NOERROR 0
#define SNMP_ES_TOOBIG 1
#define SNMP_ES_NOSUCHNAME 2
#define SNMP_ES_BADVALUE 3
#define SNMP_ES_READONLY 4
#define SNMP_ES_GENERROR 5

#define SNMP_GENTRAP_COLDSTART 0
#define SNMP_GENTRAP_WARMSTART 1
#define SNMP_GENTRAP_AUTHFAIL 4
#define SNMP_GENTRAP_ENTERPRISESPC 6

struct snmp_varbind
{
  /* next pointer, NULL for last in list */
  struct snmp_varbind *next;
  /* previous pointer, NULL for first in list */
  struct snmp_varbind *prev;

  /* object identifier length (in s32_t) */
  u8_t ident_len;
  /* object identifier array */
  s32_t *ident;

  /* object value ASN1 type */
  u8_t value_type;
  /* object value length (in u8_t) */
  u8_t value_len;
  /* object value */
  void *value;

  /* encoding varbind seq length length */
  u8_t seqlenlen;
  /* encoding object identifier length length */
  u8_t olenlen;
  /* encoding object value length length */
  u8_t vlenlen;
  /* encoding varbind seq length */
  u16_t seqlen;
  /* encoding object identifier length */
  u16_t olen;
  /* encoding object value length */
  u16_t vlen;
};

struct snmp_varbind_root
{
  struct snmp_varbind *head;
  struct snmp_varbind *tail;
  /* number of variable bindings in list */
  u8_t count;
  /* encoding varbind-list seq length length */
  u8_t seqlenlen;
  /* encoding varbind-list seq length */
  u16_t seqlen;
};

/** output response message header length fields */
struct snmp_resp_header_lengths
{
  /* encoding error-index length length */
  u8_t erridxlenlen;
  /* encoding error-status length length */
  u8_t errstatlenlen;
  /* encoding request id length length */
  u8_t ridlenlen;
  /* encoding pdu length length */
  u8_t pdulenlen;
  /* encoding community length length */
  u8_t comlenlen;
  /* encoding version length length */
  u8_t verlenlen;
  /* encoding sequence length length */
  u8_t seqlenlen;

  /* encoding error-index length */
  u16_t erridxlen;
  /* encoding error-status length */
  u16_t errstatlen;
  /* encoding request id length */
  u16_t ridlen;
  /* encoding pdu length */
  u16_t pdulen;
  /* encoding community length */
  u16_t comlen;
  /* encoding version length */
  u16_t verlen;
  /* encoding sequence length */
  u16_t seqlen;
};

/** output response message header length fields */
struct snmp_trap_header_lengths
{
  /* encoding timestamp length length */
  u8_t tslenlen;
  /* encoding specific-trap length length */
  u8_t strplenlen;
  /* encoding generic-trap length length */
  u8_t gtrplenlen;
  /* encoding agent-addr length length */
  u8_t aaddrlenlen;
  /* encoding enterprise-id length length */
  u8_t eidlenlen;
  /* encoding pdu length length */
  u8_t pdulenlen;
  /* encoding community length length */
  u8_t comlenlen;
  /* encoding version length length */
  u8_t verlenlen;
  /* encoding sequence length length */
  u8_t seqlenlen;

  /* encoding timestamp length */
  u16_t tslen;
  /* encoding specific-trap length */
  u16_t strplen;
  /* encoding generic-trap length */
  u16_t gtrplen;
  /* encoding agent-addr length */
  u16_t aaddrlen;
  /* encoding enterprise-id length */
  u16_t eidlen;
  /* encoding pdu length */
  u16_t pdulen;
  /* encoding community length */
  u16_t comlen;
  /* encoding version length */
  u16_t verlen;
  /* encoding sequence length */
  u16_t seqlen;
};

/* Accepting new SNMP messages. */
#define SNMP_MSG_EMPTY                 0
/* Search for matching object for variable binding. */
#define SNMP_MSG_SEARCH_OBJ            1
/* Perform SNMP operation on in-memory object.
   Pass-through states, for symmetry only. */
#define SNMP_MSG_INTERNAL_GET_OBJDEF   2
#define SNMP_MSG_INTERNAL_GET_VALUE    3
#define SNMP_MSG_INTERNAL_SET_TEST     4
#define SNMP_MSG_INTERNAL_GET_OBJDEF_S 5
#define SNMP_MSG_INTERNAL_SET_VALUE    6
/* Perform SNMP operation on object located externally.
   In theory this could be used for building a proxy agent.
   Practical use is for an enterprise spc. app. gateway. */
#define SNMP_MSG_EXTERNAL_GET_OBJDEF   7
#define SNMP_MSG_EXTERNAL_GET_VALUE    8
#define SNMP_MSG_EXTERNAL_SET_TEST     9
#define SNMP_MSG_EXTERNAL_GET_OBJDEF_S 10
#define SNMP_MSG_EXTERNAL_SET_VALUE    11

#define SNMP_COMMUNITY_STR_LEN 64
struct snmp_msg_pstat
{
  /* lwIP local port (161) binding */
  struct udp_pcb *pcb;
  /* source IP address */
  struct ip_addr sip;
  /* source UDP port */
  u16_t sp;
  /* request type */
  u8_t rt;
  /* request ID */
  s32_t rid;
  /* error status */
  s32_t error_status;
  /* error index */
  s32_t error_index;
  /* community name (zero terminated) */
  u8_t community[SNMP_COMMUNITY_STR_LEN + 1];
  /* community string length (exclusive zero term) */
  u8_t com_strlen;
  /* one out of MSG_EMPTY, MSG_DEMUX, MSG_INTERNAL, MSG_EXTERNAL_x */
  u8_t state;
  /* saved arguments for MSG_EXTERNAL_x */
  struct mib_external_node *ext_mib_node;
  struct snmp_name_ptr ext_name_ptr;
  struct obj_def ext_object_def;
  struct snmp_obj_id ext_oid;
  /* index into input variable binding list */
  u8_t vb_idx;
  /* ptr into input variable binding list */
  struct snmp_varbind *vb_ptr;
  /* list of variable bindings from input */
  struct snmp_varbind_root invb;
  /* list of variable bindings to output */
  struct snmp_varbind_root outvb;
  /* output response lengths used in ASN encoding */
  struct snmp_resp_header_lengths rhl;
};

struct snmp_msg_trap
{
  /* lwIP local port (161) binding */
  struct udp_pcb *pcb;
  /* destination IP address in network order */
  struct ip_addr dip;

  /* source enterprise ID (sysObjectID) */
  struct snmp_obj_id *enterprise;
  /* source IP address, raw network order format */
  u8_t sip_raw[4];
  /* generic trap code */
  u32_t gen_trap;
  /* specific trap code */
  u32_t spc_trap;
  /* timestamp */
  u32_t ts;
  /* list of variable bindings to output */
  struct snmp_varbind_root outvb;
  /* output trap lengths used in ASN encoding */
  struct snmp_trap_header_lengths thl;
};

/** Agent Version constant, 0 = v1 oddity */
extern const s32_t snmp_version;
/** Agent default "public" community string */
extern const char snmp_publiccommunity[7];

extern struct snmp_msg_trap trap_msg;

/** Agent setup, start listening to port 161. */
void snmp_init(void);
void snmp_trap_dst_enable(u8_t dst_idx, u8_t enable);
void snmp_trap_dst_ip_set(u8_t dst_idx, struct ip_addr *dst);

/** Varbind-list functions. */
struct snmp_varbind* snmp_varbind_alloc(struct snmp_obj_id *oid, u8_t type, u8_t len);
void snmp_varbind_free(struct snmp_varbind *vb);
void snmp_varbind_list_free(struct snmp_varbind_root *root);
void snmp_varbind_tail_add(struct snmp_varbind_root *root, struct snmp_varbind *vb);
struct snmp_varbind* snmp_varbind_tail_remove(struct snmp_varbind_root *root);

/** Handle an internal (recv) or external (private response) event. */
void snmp_msg_event(u8_t request_id);
err_t snmp_send_response(struct snmp_msg_pstat *m_stat);
err_t snmp_send_trap(s8_t generic_trap, struct snmp_obj_id *eoid, s32_t specific_trap);
void snmp_coldstart_trap(void);
void snmp_authfail_trap(void);

#ifdef __cplusplus
}
#endif

#endif /* __LWIP_SNMP_MSG_H__ */
