/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright 2017 Tintri by DDN, Inc. All rights reserved.
 *
 * convert binary audit records to syslog messages and
 * send them off to syslog
 *
 */

/*
 * auditd_plugin_open(), auditd_plugin() and auditd_plugin_close()
 * implement a replacable library for use by auditd; they are a
 * project private interface and may change without notice.
 *
 */
#define DEBUG   0
#if DEBUG
#define DPRINT(x) { (void) fprintf x; }
#else
#define DPRINT(x)
#endif

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <libintl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pthread.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#include <bsm/audit.h>
#include <bsm/audit_record.h>
#include <security/auditd.h>

#include "toktable.h"
#include "sysplugin.h"
#include "systoken.h"
#include <audit_plugin.h>

/* gettext() obfuscation routine for lint */
#ifdef __lint
#define gettext(x)      x
#endif

#if DEBUG
static FILE     *dbfp;                  /* debug file */
#endif

extern void init_tokens();
extern int parse_token(parse_context_t *);

static au_mask_t        mask;
static int              initialized = 0;
static size_t           maxavail;
static pthread_mutex_t  log_mutex;

#define ELLIPSIS        "..."
#define ELLIPSIS_SIZE   (sizeof (ELLIPSIS) - 1)

/*
 * simple hashing for uid and hostname lookup
 *
 * performance tests showed that cacheing the hostname, uid, and gid
 * make about a 40% difference for short audit records and regularly
 * repeating hostname, uid, etc
 *
 * ht_type and ht_ip are only used for hostname lookup cacheing.
 */
typedef struct hashtable {
        uint32_t        ht_key;
        uint32_t        ht_type;
        uint32_t        ht_ip[4];
        char            *ht_value;
        size_t          ht_length;
} hashtable_t;
#define HOSTHASHSIZE    128
#define UIDHASHSIZE     128
#define GIDHASHSIZE     32

static hashtable_t      uidhash[UIDHASHSIZE];
static hashtable_t      gidhash[GIDHASHSIZE];
static hashtable_t      hosthash[HOSTHASHSIZE];

#define STRCONSTARGS(s) (s), (sizeof (s) - 1)
/*
 * the hash "handles" collisions by overwriting the old
 * hash entry with the new.  Perfection is not the goal.
 *
 * the key (s) is a 32 bit integer, handled here as
 * four bytes.  If the hash size is increased beyond
 * 256, this macro will need some work.
 */
#define HASH(s,  r, m)  {\
                                uint32_t        _mush = 0;\
                                int             _i;\
                                for (_i = 0; _i < 4; _i++) {\
                                        _mush ^= *(s)++;\
                                }\
                                r = _mush % m;\
                        }


/*
 * The default mask for sysplugin is to reject all record types.
 * The parameters input here select which classes to allow.
 *
 * getauditflgsbin() outputs error messages to syslog.
 *
 * caller must hold log_mutex
 */

static auditd_rc_t
setmask(const char *flags)
{
        au_mask_t tmask;
        char    *input, *ip, c;
        auditd_rc_t     rc = AUDITD_SUCCESS;

        mask.am_success = 0x0;
        mask.am_failure = 0x0;

        if (flags != NULL) {
                /*
                 * getauditflagsbin doesn't like blanks, but admins do
                 */
                input = malloc(strlen(flags) + 1);
                if (input == NULL)
                        return (AUDITD_NO_MEMORY);

                ip = input;

                for (; (c = *flags) != '\0'; flags++) {
                        if (c == ' ')
                                continue;
                        *ip++ = c;
                }
                *ip = '\0';
                if (getauditflagsbin(input, &tmask) == 0) {
                        mask.am_success |= tmask.am_success;
                        mask.am_failure |= tmask.am_failure;
                }
        }
        if ((mask.am_success | mask.am_failure) == 0) {
                rc = AUDITD_INVALID;
                __audit_syslog("audit_syslog.so", LOG_CONS | LOG_NDELAY,
                    LOG_DAEMON, LOG_ERR,
                    gettext("plugin is configured with empty class mask\n"));
        }
        free(input);
        return (rc);
}

/*
 * based on the current value of mask, either keep or toss the
 * current audit record.  The input is 1 for success, -1 for
 * failure.  0 means no exit or return token was seen.
 *
 * au_preselect returns 1 for keep it, 0 for delete it, and
 * -1 for some sort of error.  Here, 1 and -1 are considered
 * equivalent.  tossit() returns 1 for delete it and 0 for
 * keep it.
 */

static int
tossit(au_event_t id, int passfail)
{
        int     rc;
        int     selFlag;

        switch (passfail) {
        case 1:
                selFlag = AU_PRS_SUCCESS;
                break;
        case -1:
                selFlag = AU_PRS_FAILURE;
                break;
        default:                /* no exit or return token */
                selFlag = AU_PRS_BOTH;
                break;
        }
        (void) pthread_mutex_lock(&log_mutex);
        rc = au_preselect(id, &mask, selFlag, AU_PRS_USECACHE);
        (void) pthread_mutex_unlock(&log_mutex);

        return (rc == 0);
}

/*
 * the three bytes for ellipsis could potentially be longer than the
 * space available for text if maxavail is within two bytes of
 * OUTPUT_BUF_SIZE, which can happen if the hostname is one or two
 * characters long.  If there isn't room for ellipsis, there isn't
 * room for the data, so it is simply dropped.
 */

static size_t
fromleft(char *p, size_t avail, char *attrname, size_t attrlen, char *txt,
    size_t txtlen)
{
        size_t  len;

        if (avail < attrlen + ELLIPSIS_SIZE)
                return (0);

        (void) memcpy(p, attrname, attrlen);
        p += attrlen;
        avail -= attrlen;
        if (txtlen > avail) {
                (void) memcpy(p, ELLIPSIS, ELLIPSIS_SIZE);
                txt += txtlen - (avail - ELLIPSIS_SIZE);
                (void) memcpy(p + ELLIPSIS_SIZE, txt, avail - ELLIPSIS_SIZE);
                len = attrlen + avail;
                p += avail;
        } else {
                (void) memcpy(p, txt, txtlen);
                len = attrlen + txtlen;
                p += txtlen;
        }
        *p = '\0';
        return (len);
}

static size_t
fromright(char *p, size_t avail, char *attrname, size_t attrlen, char *txt,
    size_t txtlen)
{
        size_t  len;

        if (avail < attrlen + ELLIPSIS_SIZE)
                return (0);

        (void) memcpy(p, attrname, attrlen);
        p += attrlen;
        avail -= attrlen;
        if (txtlen > avail) {
                (void) memcpy(p, txt, avail - ELLIPSIS_SIZE);
                (void) memcpy(p + (avail - ELLIPSIS_SIZE),
                    ELLIPSIS, ELLIPSIS_SIZE);
                len = attrlen + avail;
                p += avail;
        } else {
                (void) memcpy(p, txt, txtlen);
                p += txtlen;
                len = attrlen + txtlen;
        }
        *p = '\0';
        return (len);
}

static int
init_hash(hashtable_t *table, int bad_key, int table_length,
    size_t max_value)
{
        int     i;

        for (i = 0; i < table_length; i++) {
                table[i].ht_value = malloc(max_value + 1);
                table[i].ht_key = bad_key;
                table[i].ht_length = 0;
                if (table[i].ht_value == NULL) {
                        int     j;
                        for (j = 0; j < i; j++)
                                free(table[j].ht_value);
                        return (-1);
                }
                *(table[i].ht_value) = '\0';
        }
        return (0);
}

static void
free_hash(hashtable_t *table, int table_length)
{
        int     i;

        for (i = 0; i < table_length; i++) {
                free(table[i].ht_value);
        }
}


/*
 * do IP -> hostname lookup
 */
#define UNKNOWN         "unknown"
#define UNKNOWN_LEN     (sizeof (UNKNOWN))

static size_t
gethname(au_tid_addr_t *tid, char *p, size_t max, char *prefix,
    size_t prefix_len)
{
        size_t                  len, l;
        struct hostent          *host;
        int                     rc;
        int                     af;
        int                     ix;
        char                    *hash_key;
        uint32_t                key;
        int                     match;

        if (prefix_len > max)
                return (0);

        (void) memcpy(p, prefix, prefix_len);
        p += prefix_len;
        max -= prefix_len;

        if (tid->at_type == AU_IPv6) {
                key = tid->at_addr[0] ^
                    tid->at_addr[1] ^
                    tid->at_addr[2] ^
                    tid->at_addr[3];
        } else
                key = (tid->at_addr[0]);

        hash_key = (char *)&key;

        HASH(hash_key, ix, HOSTHASHSIZE);

        match = 0;

        if (key == 0) {
                l = UNKNOWN_LEN;        /* includes end of string */
                if (l > max)
                        l = max;
                len = prefix_len + strlcpy(p, UNKNOWN, l);
                return (len);
        }

        if (tid->at_type == AU_IPv6) {
                if ((key == hosthash[ix].ht_key) &&
                    (hosthash[ix].ht_type == tid->at_type)) {
                        int i;
                        match = 1;
                        for (i = 0; i < 4; i++) {
                                if (hosthash[ix].ht_ip[i] != tid->at_addr[i]) {
                                        match = 0;
                                        break;
                                }
                        }
                }
        } else if (key == hosthash[ix].ht_key) {
                match = 1;
        }
        if (!match) {
                hosthash[ix].ht_key = key;
                hosthash[ix].ht_type = tid->at_type;

                if (tid->at_type == AU_IPv4) {
                        hosthash[ix].ht_ip[0] = tid->at_addr[0];
                        af = AF_INET;
                } else {
                        (void) memcpy((char *)hosthash[ix].ht_ip,
                            (char *)tid->at_addr, AU_IPv6);
                        af = AF_INET6;
                }
                host = getipnodebyaddr((const void *)tid->at_addr,
                    tid->at_type, af, &rc);

                if (host == NULL) {
                        (void) inet_ntop(af, (void *)tid->at_addr,
                            hosthash[ix].ht_value, MAXHOSTNAMELEN);
                        hosthash[ix].ht_length = strlen(hosthash[ix].ht_value);
                } else {
                        hosthash[ix].ht_length = strlcpy(hosthash[ix].ht_value,
                            host->h_name,  MAXHOSTNAMELEN);
                        freehostent(host);
                }
        }
        l = hosthash[ix].ht_length + 1;
        if (l > max)
                l = max;

        len = prefix_len + strlcpy(p, hosthash[ix].ht_value, l);

        return (len);
}
/*
 * the appropriate buffer length for getpwuid_r() isn't documented;
 * 1024 should be enough.
 */
#define GETPWUID_BUFF_LEN       1024
#define USERNAMELEN             256
#define GIDNAMELEN              256

static size_t
getuname(uid_t uid, gid_t gid, char *p, size_t max, char *prefix,
    size_t prefix_len)
{
        struct passwd           pw;
        char                    pw_buf[GETPWUID_BUFF_LEN];
        size_t                  len, l;
        struct group            gr;
        int                     ix;
        char                    *hash_key;

        if (prefix_len > max)
                return (0);

        len = prefix_len;

        (void) memcpy(p, prefix, len);
        p += len;
        max -= len;

        hash_key = (char *)&uid;

        HASH(hash_key, ix, UIDHASHSIZE);

        if (uid != uidhash[ix].ht_key) {
                uidhash[ix].ht_key = uid;

                if ((getpwuid_r(uid, &pw, pw_buf, GETPWUID_BUFF_LEN)) == NULL)
                        l = snprintf(uidhash[ix].ht_value, USERNAMELEN,
                            "%d", uid);
                else
                        l = strlcpy(uidhash[ix].ht_value, pw.pw_name,
                            USERNAMELEN);

                uidhash[ix].ht_length = l;
        }
        l = uidhash[ix].ht_length + 1;
        if (l > max)
                l = max;
        (void) memcpy(p, uidhash[ix].ht_value, l);
        len += l - 1;

        if (gid != (gid_t)-2) {
                p += l - 1;
                max -= l - 1;
                if (max < 2)
                        return (len);

                hash_key = (char *)&gid;
                HASH(hash_key, ix, GIDHASHSIZE);

                if (gid != gidhash[ix].ht_key) {
                        gidhash[ix].ht_key = gid;

                        if (getgrgid_r(gid, &gr,  pw_buf, GETPWUID_BUFF_LEN) ==
                            NULL)
                                gidhash[ix].ht_length =
                                    snprintf(gidhash[ix].ht_value, GIDNAMELEN,
                                    "%d", gid);
                        else
                                gidhash[ix].ht_length =
                                    strlcpy(gidhash[ix].ht_value,
                                    gr.gr_name, GIDNAMELEN);
                }
                *p++ = ':';
                len++;
                max--;

                l = gidhash[ix].ht_length + 1;
                if (l > max)
                        l = max;
                (void) memcpy(p, gidhash[ix].ht_value, l);
                len += l - 1;
        }
        return (len);
}

/*
 * filter() parse input; toss if not wanted.
 *
 * the input value sequence is a number generated when the buffer
 * was queued.  ctx.out.sf_sequence, if not -1, is the sequence number
 * generated in c2audit.  It is not part of the "official" syslog
 * output but is included if DEBUG is on.
 */
#define EVENT_NAME_LEN  32

static auditd_rc_t
filter(const char *input, uint64_t sequence, char *output,
    size_t in_len, size_t out_len)
{
        parse_context_t         ctx;
        char                    *bp;
        auditd_rc_t             rc = AUDITD_SUCCESS;
        auditd_rc_t             rc_ret = AUDITD_SUCCESS;
        size_t                  used, remaining;
        char                    *last_adr; /* infinite loop check */
        int                     token_count = 0;
        int                     parse_rc;

        static parse_context_t  initial_ctx;
        static int              first = 1;

        if (first) {
                first = 0;

                /*
                 * Any member or submember of parse_context_t which utilizes
                 * allocated memory must free() the memory after calling
                 * parse_token() for both the preselected and non-preselected
                 * cases.
                 * New additions to parse_context_t or its submembers need to
                 * have this same treatment.
                 */
                initial_ctx.out.sf_eventid = 0;
                initial_ctx.out.sf_reclen = 0;
                initial_ctx.out.sf_pass = 0;
                initial_ctx.out.sf_asid = 0;
                initial_ctx.out.sf_auid = (uid_t)-2;
                initial_ctx.out.sf_euid = (uid_t)-2;
                initial_ctx.out.sf_egid = (gid_t)-2;
                initial_ctx.out.sf_tid.at_type = 0;
                initial_ctx.out.sf_pauid = (uid_t)-2;
                initial_ctx.out.sf_peuid = (uid_t)-2;
                initial_ctx.out.sf_uauthlen = 0;
                initial_ctx.out.sf_uauth = NULL;
                initial_ctx.out.sf_pathlen = 0;
                initial_ctx.out.sf_path = NULL;
                initial_ctx.out.sf_atpathlen = 0;
                initial_ctx.out.sf_atpath = NULL;
                initial_ctx.out.sf_textlen = 0;
                initial_ctx.out.sf_text = NULL;
                initial_ctx.out.sf_sequence = -1;
                initial_ctx.out.sf_zonelen = 0;
                initial_ctx.out.sf_zonename = NULL;

                init_tokens();          /* cmd/praudit/toktable.c */
        }
        (void) memcpy(&ctx, &initial_ctx, sizeof (parse_context_t));
        ctx.id = sequence;
        ctx.adr.adr_stream = (char *)input;
        ctx.adr.adr_now = (char *)input;

        last_adr = NULL;
        while ((ctx.adr.adr_now - ctx.adr.adr_stream) < in_len) {
                assert(last_adr != ctx.adr.adr_now);
                token_count++;
                last_adr = ctx.adr.adr_now;
                if ((parse_rc = parse_token(&ctx)) != 0) {
                        char    message[256];
                        au_event_ent_t  *event;
                        char    event_name[EVENT_NAME_LEN];
                        char    sequence_str[EVENT_NAME_LEN];

                        if (cacheauevent(&event, ctx.out.sf_eventid) < 0)
                                (void) snprintf(event_name, EVENT_NAME_LEN,
                                    "%hu", ctx.out.sf_eventid);
                        else
                                (void) strlcpy(event_name, event->ae_desc,
                                    EVENT_NAME_LEN);

                        if (token_count < 2)
                                /* leave rc_ret unchanged */
                                rc = AUDITD_INVALID;

                        if (ctx.out.sf_sequence != -1)
                                (void) snprintf(sequence_str, EVENT_NAME_LEN,
                                    " (seq=%u) ", ctx.out.sf_sequence);
                        else
                                sequence_str[0] = '\0';

                        (void) snprintf(message, 256,
                            gettext("error before token %d (previous token=%d)"
                            " of record type %s%s\n"),
                            token_count, parse_rc, event_name, sequence_str);

#if DEBUG
                        /*LINTED*/
                        (void) fprintf(dbfp, message);
#endif

                        __audit_syslog("audit_syslog.so",
                            LOG_PID | LOG_ODELAY | LOG_CONS,
                            LOG_DAEMON, LOG_ALERT, message);
                        break;
                }
        }
        if (rc == AUDITD_SUCCESS) {
                if (tossit(ctx.out.sf_eventid, ctx.out.sf_pass)) {
#if DEBUG
                        if (ctx.out.sf_sequence != -1)
                                (void) fprintf(dbfp,
                                    "syslog tossed (event=%hu) record %u "
                                    "/ buffer %llu\n",
                                    ctx.out.sf_eventid, ctx.out.sf_sequence,
                                    sequence);
                        else
                                (void) fprintf(dbfp,
                                    "syslog tossed (event=%hu) buffer %llu\n",
                                    ctx.out.sf_eventid, sequence);
#endif

                        /*
                         * Members or submembers of parse_context_t which
                         * utilize allocated memory need to free() the memory
                         * here to handle the case of not being preselected as
                         * well as below for when the event is preselected.
                         * New additions to parse_context_t or any of its
                         * submembers need to get the same treatment.
                         */
                        if (ctx.out.sf_uauthlen > 0) {
                                free(ctx.out.sf_uauth);
                                ctx.out.sf_uauth = NULL;
                                ctx.out.sf_uauthlen = 0;
                        }
                        if (ctx.out.sf_pathlen > 0) {
                                free(ctx.out.sf_path);
                                ctx.out.sf_path = NULL;
                                ctx.out.sf_pathlen = 0;
                        }
                        if (ctx.out.sf_atpathlen > 0) {
                                free(ctx.out.sf_atpath);
                                ctx.out.sf_atpath = NULL;
                                ctx.out.sf_atpathlen = 0;
                        }
                        if (ctx.out.sf_textlen > 0) {
                                free(ctx.out.sf_text);
                                ctx.out.sf_text = NULL;
                                ctx.out.sf_textlen = 0;
                        }
                        if (ctx.out.sf_zonelen > 0) {
                                free(ctx.out.sf_zonename);
                                ctx.out.sf_zonename = NULL;
                                ctx.out.sf_zonelen = 0;
                        }

                        return (AUDITD_DISCARD);
                }
                bp = output;
                remaining = out_len;

                if (ctx.out.sf_eventid != 0) {
                        au_event_ent_t  *event;

                        if (cacheauevent(&event, ctx.out.sf_eventid) < 0)
                                used = snprintf(bp, remaining, "%hu",
                                    ctx.out.sf_eventid);
                        else
                                used = strlcpy(bp, event->ae_desc, remaining);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_pass != 0) {
                        if (ctx.out.sf_pass < 0)
                                used = strlcpy(bp, " failed", remaining);
                        else
                                used = strlcpy(bp, " ok", remaining);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_asid != 0) {
                        used = snprintf(bp, remaining, " session %u",
                            ctx.out.sf_asid);
                        remaining -= used;
                        bp += used;
                }
                if (ctx.out.sf_auid != (uid_t)-2) {
                        used = getuname(ctx.out.sf_auid, -2, bp, remaining,
                            STRCONSTARGS(" by "));
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_euid != (uid_t)-2) {
                        /* 4 = strlen(" as ") */
                        used = getuname(ctx.out.sf_euid, ctx.out.sf_egid, bp,
                            remaining, STRCONSTARGS(" as "));
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_zonename != NULL) {
                        used = fromright(bp, remaining,
                            STRCONSTARGS(" in "),
                            ctx.out.sf_zonename, ctx.out.sf_zonelen);
                        free(ctx.out.sf_zonename);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_tid.at_type != 0) {
                        /* 6 = strlen(" from ") */
                        used = gethname(&(ctx.out.sf_tid), bp, remaining,
                            STRCONSTARGS(" from "));
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_pauid != (uid_t)-2) {
                        /* 11 = strlen(" proc_auid ") */
                        used = getuname(ctx.out.sf_pauid, -2, bp, remaining,
                            STRCONSTARGS(" proc_auid "));
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_peuid != (uid_t)-2) {
                        used = getuname(ctx.out.sf_peuid, -2, bp, remaining,
                            STRCONSTARGS(" proc_uid "));
                        bp += used;
                        remaining -= used;
                }
#if DEBUG
                /*
                 * with performance testing, this has the effect of
                 * making that each message is unique, so syslogd
                 * won't collect a series of messages as "last message
                 * repeated n times," another reason why DEBUG 0
                 * should perform better than DEBUG 1.  However the
                 * intention is to help debug lost data problems
                 */
                if (ctx.out.sf_sequence != -1) {
                        (void) fprintf(dbfp,
                            "syslog writing record %u / buffer %llu\n",
                            ctx.out.sf_sequence, sequence);
                        used = snprintf(bp, remaining, "  seq %u",
                            ctx.out.sf_sequence, sequence);
                        remaining -= used;
                        bp += used;
                } else
                        (void) fprintf(dbfp, "syslog writing buffer %llu\n",
                            sequence);
#endif
                /*
                 * Long fields that may need truncation go here in
                 * order of decreasing priority.  Paths are truncated
                 * from the left, text from the right.
                 */
                if (ctx.out.sf_path != NULL) {
                        used = fromleft(bp, remaining, STRCONSTARGS(" obj "),
                            ctx.out.sf_path, ctx.out.sf_pathlen);
                        free(ctx.out.sf_path);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_atpath != NULL) {
                        used = fromleft(bp, remaining,
                            STRCONSTARGS(" attr_obj "),
                            ctx.out.sf_atpath, ctx.out.sf_atpathlen);
                        free(ctx.out.sf_atpath);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_uauth != NULL) {
                        used = fromright(bp, remaining, STRCONSTARGS(" uauth "),
                            ctx.out.sf_uauth, ctx.out.sf_uauthlen);
                        free(ctx.out.sf_path);
                        bp += used;
                        remaining -= used;
                }
                if (ctx.out.sf_text != NULL) {
                        used = fromright(bp, remaining,
                            STRCONSTARGS(AU_TEXT_NAME),
                            ctx.out.sf_text, ctx.out.sf_textlen);
                        free(ctx.out.sf_text);
                        bp += used;
                        remaining -= used;
                }
        }
        return (rc_ret);
}

/*
 * 1024 is max syslog record size, 48 is minimum header length,
 * assuming a hostname length of 0.  maxavail reduces use of the
 * allocated space by the length of the hostname (see maxavail)
 */
#define OUTPUT_BUF_SIZE 1024 - 48

/* ARGSUSED */
auditd_rc_t
auditd_plugin(const char *input, size_t in_len, uint64_t sequence, char **error)
{
        char            *outbuf;
        auditd_rc_t     rc = AUDITD_SUCCESS;
#if DEBUG
        static  uint64_t        last_sequence = 0;
        static  uint64_t        write_count = 0;
        static  uint64_t        toss_count = 0;

        if ((last_sequence > 0) && (sequence != last_sequence + 1))
                (void) fprintf(dbfp,
                    "syslog: buffer sequence=%llu but prev=%llu\n",
                    sequence, last_sequence);
        last_sequence = sequence;
#endif

        *error = NULL;

        outbuf = malloc(OUTPUT_BUF_SIZE);
        if (outbuf == NULL) {
                DPRINT((dbfp, "syslog: out of memory; seq=%llu\n",
                    sequence));
                rc = AUDITD_NO_MEMORY;
                *error = strdup(gettext("Can't allocate buffers"));
        } else {
                rc = filter(input, sequence, outbuf, in_len, maxavail);

                if (rc == AUDITD_SUCCESS) {
                        __audit_syslog("audit", LOG_NDELAY,
                            LOG_AUDIT, LOG_NOTICE, outbuf);
                        DPRINT((dbfp, "syslog: write_count=%llu, "
                            "buffer=%llu, tossed=%llu\n",
                            ++write_count, sequence, toss_count));
                } else if (rc != AUDITD_DISCARD) {
                        DPRINT((dbfp, "syslog: parse failed for buffer %llu\n",
                            sequence));
                        *error = strdup(gettext(
                            "Unable to parse audit record"));
                } else {
                        DPRINT((dbfp, "syslog: rc = %d (%d is discard), "
                            "sequence=%llu, toss_count=%llu\n",
                            rc, AUDITD_DISCARD, sequence, ++toss_count));
                        rc = AUDITD_SUCCESS;
                }
                free(outbuf);
        }
        return (rc);
}

auditd_rc_t
auditd_plugin_open(const kva_t *kvlist, char **ret_list, char **error)
{
        char            localname[MAXHOSTNAMELEN + 1];
        auditd_rc_t     rc;
        char            *value;
        /* kva_match doesn't do const, so copy the pointer */
        kva_t           *kva = (kva_t *)kvlist;

        *error = NULL;
        *ret_list = NULL;

        if ((kvlist == NULL) || ((value = kva_match(kva, "p_flags")) == NULL)) {
                *error = strdup(gettext(
                    "The \"p_flags\" attribute is missing."));
                return (AUDITD_INVALID);
        }
        if (!initialized) {
#if DEBUG
                dbfp = __auditd_debug_file_open();
#endif
                initialized = 1;
                (void) pthread_mutex_init(&log_mutex, NULL);
                /*
                 * calculate length of the local hostname for adjusting the
                 * estimate of how much space is taken by the syslog header.
                 * If the local hostname isn't available, leave some room
                 * anyway.  (The -2 is for the blanks on either side of the
                 * hostname in the syslog message.)
                 */
                (void) pthread_mutex_lock(&log_mutex);
                if (gethostname(localname, MAXHOSTNAMELEN))
                        maxavail = OUTPUT_BUF_SIZE - 20;
                else
                        maxavail = OUTPUT_BUF_SIZE - strlen(localname) - 2;
                (void) pthread_mutex_unlock(&log_mutex);

                if (init_hash(hosthash, 0, HOSTHASHSIZE, MAXHOSTNAMELEN))
                        return (AUDITD_NO_MEMORY);

                if (init_hash(uidhash, -2, UIDHASHSIZE, USERNAMELEN))
                        return (AUDITD_NO_MEMORY);

                if (init_hash(gidhash, -2, GIDHASHSIZE, GIDNAMELEN))
                        return (AUDITD_NO_MEMORY);
        }
        (void) pthread_mutex_lock(&log_mutex);
        if ((rc = setmask(value)) != AUDITD_SUCCESS)
                *error = strdup(gettext(
                    "incorrect p_flags setting; no records will be output"));

        (void) pthread_mutex_unlock(&log_mutex);

        return (rc);
}

auditd_rc_t
auditd_plugin_close(char **error)
{
        *error = NULL;

        if (initialized) {
                (void) pthread_mutex_destroy(&log_mutex);

                free_hash(hosthash, HOSTHASHSIZE);
                free_hash(uidhash, UIDHASHSIZE);
                free_hash(gidhash, GIDHASHSIZE);
        }
        initialized = 0;

        return (AUDITD_SUCCESS);
}