/*      $OpenBSD: snmp.h,v 1.7 2020/01/17 09:52:44 martijn Exp $        */

/*
 * Copyright (c) 2019 Martijn van Duren <martijn@openbsd.org>
 * Copyright (c) 2007, 2008, 2012 Reyk Floeter <reyk@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef SNMPD_SNMP_H
#define SNMPD_SNMP_H

#include <sys/types.h>
#include <sys/queue.h>
#include <endian.h>

#include <time.h>

#define READ_BUF_SIZE 65535

#define SNMP_MAX_OID_STRLEN     128     /* max size of the OID _string_ */

/*
 * SNMP BER types
 */

enum snmp_version {
        SNMP_V1                 = 0,
        SNMP_V2C                = 1,    /* SNMPv2c */
        SNMP_V3                 = 3
};

enum snmp_context {
        SNMP_C_GETREQ           = 0,
        SNMP_C_GETNEXTREQ       = 1,
        SNMP_C_GETRESP          = 2,
        SNMP_C_SETREQ           = 3,
        SNMP_C_TRAP             = 4,

        /* SNMPv2 */
        SNMP_C_GETBULKREQ       = 5,
        SNMP_C_INFORMREQ        = 6,
        SNMP_C_TRAPV2           = 7,
        SNMP_C_REPORT           = 8
};

enum snmp_application {
        SNMP_T_IPADDR           = 0,
        SNMP_T_COUNTER32        = 1,
        SNMP_T_GAUGE32          = 2,
        SNMP_T_UNSIGNED32       = 2,
        SNMP_T_TIMETICKS        = 3,
        SNMP_T_OPAQUE           = 4,
        SNMP_T_NSAPADDR         = 5,
        SNMP_T_COUNTER64        = 6,
        SNMP_T_UINTEGER32       = 7
};

enum snmp_generic_trap {
        SNMP_TRAP_COLDSTART     = 0,
        SNMP_TRAP_WARMSTART     = 1,
        SNMP_TRAP_LINKDOWN      = 2,
        SNMP_TRAP_LINKUP        = 3,
        SNMP_TRAP_AUTHFAILURE   = 4,
        SNMP_TRAP_EGPNEIGHLOSS  = 5,
        SNMP_TRAP_ENTERPRISE    = 6
};

enum snmp_error {
        SNMP_ERROR_NONE         = 0,
        SNMP_ERROR_TOOBIG       = 1,
        SNMP_ERROR_NOSUCHNAME   = 2,
        SNMP_ERROR_BADVALUE     = 3,
        SNMP_ERROR_READONLY     = 4,
        SNMP_ERROR_GENERR       = 5,

        /* SNMPv2 */
        SNMP_ERROR_NOACCESS     = 6,
        SNMP_ERROR_WRONGTYPE    = 7,
        SNMP_ERROR_WRONGLENGTH  = 8,
        SNMP_ERROR_WRONGENC     = 9,
        SNMP_ERROR_WRONGVALUE   = 10,
        SNMP_ERROR_NOCREATION   = 11,
        SNMP_ERROR_INCONVALUE   = 12,
        SNMP_ERROR_RESUNAVAIL   = 13, /* EGAIN */
        SNMP_ERROR_COMMITFAILED = 14,
        SNMP_ERROR_UNDOFAILED   = 15,
        SNMP_ERROR_AUTHERROR    = 16,
        SNMP_ERROR_NOTWRITABLE  = 17,
        SNMP_ERROR_INCONNAME    = 18
};

enum snmp_security_model {
        SNMP_SEC_ANY            = 0,
        SNMP_SEC_SNMPv1         = 1,
        SNMP_SEC_SNMPv2c        = 2,
        SNMP_SEC_USM            = 3,
        SNMP_SEC_TSM            = 4
};

enum snmp_application_exception {
        SNMP_E_NOSUCHOBJECT     = 0,
        SNMP_E_NOSUCHINSTANCE   = 1,
        SNMP_E_ENDOFMIB         = 2
};

struct snmp_agent;

struct snmp_sec {
        enum snmp_security_model model;
        int (*init)(struct snmp_agent *);
        char *(*genparams)(struct snmp_agent *, size_t *, void **);
        struct ber_element *(*encpdu)(struct snmp_agent *,
            struct ber_element *, void *);
        int (*finalparams)(struct snmp_agent *, char *, size_t, size_t, void *);
        int (*parseparams)(struct snmp_agent *, char *, size_t, off_t, char *,
            size_t, uint8_t, void **);
        struct ber_element *(*decpdu)(struct snmp_agent *, char *, size_t,
            void *);
        void (*free)(void *);
        void (*freecookie)(void *);
        void *data;
};

struct snmp_v3 {
        uint8_t level;
        char *ctxname;
        size_t ctxnamelen;
        int engineidset;
        char *engineid;
        size_t engineidlen;
        struct snmp_sec *sec;
};

struct snmp_agent {
        int fd;
        int timeout;
        int retries;
        enum snmp_version version;
/* SNMP_V1 & SNMP_V2C */
        char *community;
/* SNMP_V3 */
        struct snmp_v3 *v3;
};

#define SNMP_MSGFLAG_AUTH       0x01
#define SNMP_MSGFLAG_PRIV       0x02
#define SNMP_MSGFLAG_SECMASK    (SNMP_MSGFLAG_AUTH | SNMP_MSGFLAG_PRIV)
#define SNMP_MSGFLAG_REPORT     0x04

#define SNMP_MAX_TIMEWINDOW     150     /* RFC3414 */

struct snmp_v3 *snmp_v3_init(int, const char *, size_t, struct snmp_sec *);
int snmp_v3_setengineid(struct snmp_v3 *, char *, size_t);
struct snmp_agent *snmp_connect_v12(int, enum snmp_version, const char *);
struct snmp_agent *snmp_connect_v3(int, struct snmp_v3 *);
void snmp_free_agent(struct snmp_agent *);
struct ber_element *
    snmp_get(struct snmp_agent *agent, struct ber_oid *oid, size_t len);
struct ber_element *snmp_getnext(struct snmp_agent *, struct ber_oid *, size_t);
struct ber_element *
    snmp_getbulk(struct snmp_agent *, struct ber_oid *, size_t, int, int);
struct ber_element *snmp_set(struct snmp_agent *, struct ber_element *);
int snmp_trap(struct snmp_agent *, struct timespec *, struct ber_oid *,
    struct ber_element *);

ssize_t ber_copy_writebuf(struct ber *, void **);

#endif /* SNMPD_SNMP_H */