/*
 * Copyright (c) 2006, Stefan Walter
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above
 *       copyright notice, this list of conditions and the
 *       following disclaimer.
 *     * 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.
 *     * The names of contributors to this software may not be
 *       used to endorse or promote products derived from this
 *       software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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
 * COPYRIGHT OWNER OR CONTRIBUTORS 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.
 *
 *
 * CONTRIBUTORS
 *  Stef Walter <stef@memberwebs.com>
 */

#include "usuals.h"

#include <sys/types.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/un.h>
#include <syslog.h>
#include <unistd.h>
#include <stdarg.h>
#include <ctype.h>
#include <fcntl.h>

#include <bsnmp/snmpmod.h>

#include "sysctl_sup.h"

#include "sysctl_tree.h"
#include "sysctl_oid.h"

#define DEFAULT_CONFIG      "/usr/local/etc" "/bsnmp-sysctl.conf"
#define DEFAULT_CACHE       10

/* our module handle */
static struct lmodule *module;

/* OIDs */
static const struct asn_oid oid_sysctl = OIDX_sysctl;

/* the Object Resource registration index */
static u_int reg_index = 0;

struct data_entry {
    uint32_t                index;
    TAILQ_ENTRY(data_entry) link;

    char                    *descr;
    char                    *fmt;
    u_int                   type;

    uint64_t                cache;
    int                     error;

    char                    *sysctl;
    int                     *name;
    u_int                   namelen;

    uint64_t                last_update;
    int64_t                 value_int;
    char                    *value_raw;
    size_t                  value_rawlen;
    char                    *value_str;
    size_t                  value_strlen;
};

TAILQ_HEAD(data_entry_list, data_entry);

/* list of sysctls */
static struct data_entry_list entries = TAILQ_HEAD_INITIALIZER(entries);
static uint32_t entry_count = 0;

/* configuration */
static u_char *sysctl_config = NULL;
static char *config_memory = NULL;
static uint64_t option_cache = DEFAULT_CACHE;

/* -----------------------------------------------------------------------------
 * HELPERS
 */

static void
emsg(const char *format, ...)
{
    va_list va;
    va_start(va, format);
    vsyslog(LOG_ERR, format, va);
    va_end(va);
}

static void
strcln (char* data, char ch)
{
    char* p;
    for (p = data; *data; data++, p++) {
        while (*data == ch)
            data++;
        *p = *data;
    }
    /* null terminate */
    *p = 0;
}

static void
stretrim (char* data)
{
    char* t = data + strlen (data);
    while (t > data && isspace (*(t - 1))) {
        t--;
        *t = 0;
    }
}

static char*
strbtrim (char* data)
{
    while (*data && isspace (*data))
        ++data;
    return (char*)data;
}

static char*
strtrim (char* data)
{
    data = (char*)strbtrim (data);
    stretrim (data);
    return data;
}

static uint64_t
getcurrticks (void)
{
    return get_ticks ();
}

/* -----------------------------------------------------------------------------
 * CONFIG PARSING
 */

static void
config_free (struct data_entry *data)
{

    free(data->name);
    free(data->fmt);
    free (data->value_str);
    free (data->value_raw);

    free (data);
}

static void
config_free_all (void)
{
    struct data_entry *data;
    while ((data = TAILQ_FIRST(&entries)) != NULL) {
        TAILQ_REMOVE (&entries, data, link);
        config_free (data);
    }
}

static int
config_entry (struct data_entry *data, char *name, char *value,
              int line)
{

    ASSERT (data);
    ASSERT (name);
    ASSERT (value);

    (void)value;

    /* The name */
    data->descr = name;        /* XXX - from sysctl desc */
    data->sysctl = name;
    data->error = 0;

    /* Parse the sysctl */
    data->namelen = CTL_MAXNAME;
    data->name = malloc(sizeof *data->name * data->namelen);
    data->fmt = NULL;
    data->value_str = NULL;
    data->value_raw = NULL;

    if (data->name == NULL) {
        emsg ("out of memory parsing config file");
        return -1;
    }
    do {
        if (sysctlnametomib(name, data->name, &data->namelen) == -1) {
            emsg ("[line %d] sysctlnametomib: %s", line, strerror(errno));
            break;
        }

        data->name = realloc(data->name, sizeof *data->name * data->namelen);

        if (sysctl_oidfmt(data->name, data->namelen, &data->fmt, &data->type)) {
            emsg ("[line %d] sysctl_oidfmt: %s", line, strerror(errno));
            break;
        }

        /* Options */
        data->cache = option_cache;

        return 0;
    } while (0);

    free(data->name);
    free(data->fmt);
    return -1;
}

static int
config_line (char *name, char *value, int line)
{
    struct data_entry *data;
    int r;

    /* config_parse trims this for us */
    ASSERT (!isspace(value[0]));

    /* Now populate an entry */
    data = (struct data_entry*)calloc(1, sizeof *data);
    if (!data) {
        emsg ("out of memory");
        return -1;
    }

    /* Now make an entry out of it all */
    r = config_entry (data, name, value, line);

    if (r < 0) {
        free (data);
        return r;
    }

    /* Put it in our table */
    data->index = entry_count++;
    INSERT_OBJECT_INT (data, &entries);

    return 0;
}

static void
config_var (char *name, char *value, int line)
{
    char *t2;
    int i;

    /* The cache variable */
    if (strcmp (name, "cache") == 0) {

        i = strtol (value, &t2, 10);
        if (i <= 0 || *t2)
            emsg("[line %d] invalid value for '%s' variable. ignoring: %s",
                line, name, value);
        else
            option_cache = i * 100;
        return;
    }

    emsg ("unknown or invalid variable. ignoring: %s", name);
}

static int
config_read (void)
{
    FILE *f = NULL;
    long len;

    ASSERT (sysctl_config && sysctl_config[0]);

    f = fopen (sysctl_config, "r");
    if (f == NULL) {
        emsg ("couldn't open config file: %s", sysctl_config);
        return -1;
    }

    /* Figure out size */
    if (fseek (f, 0, SEEK_END) == -1 || (len = ftell (f)) == -1 || fseek (f, 0, SEEK_SET) == -1) {
        emsg ("couldn't seek config file: %s", sysctl_config);
        return -1;
    }

    ASSERT (!config_memory);

    if ((config_memory = (char*)malloc (len + 2)) == NULL) {
        emsg ("out of memory");
        return -1;
    }

    /* And read in one block */
    if(fread(config_memory, 1, len, f) != (size_t)len) {
        emsg ("couldn't read config file: %s", sysctl_config);
        free (config_memory);
        config_memory = NULL;
        return -1;
    }

    fclose (f);

    /* Null terminate the data */
    config_memory[len] = '\n';
    config_memory[len + 1] = 0;

    return 0;
}

static int
config_parse (void)
{
    char* next;
    char* p;
    char* t;
    int line = 0;
    int var = 0;
    int r;

    config_free_all ();

    /* Reads raw config file into config_memory */
    if (config_read () < 0)
        return -1;

    ASSERT (config_memory);

   /* Remove nasty dos line endings */
    strcln(config_memory, '\r');

    next = config_memory;
    while ((t = strchr (next, '\n')) != NULL) {

        *t = 0;
        p = next;
        next = t + 1;
        t = strbtrim (p);
        line++;

        /* blank lines, comments */
        if (!*t || *t == '#')
            continue;

        t = t + strcspn (t, ":=");
        if (!*t) {
            emsg ("invalid config line: %s", p);
            return -1;
        }

        /* Equal sign denotes a variable */
        var = (*t == '=');
        *t = 0;
        t++;

        /* Pass variables to the appropriate place */
        if (var) {
            config_var (strtrim (p), strtrim (t), line);

        /* And config lines to the appropriate place */
        } else {

            r = config_line (strtrim (p), strtrim (t), line);
            if (r < 0) {

                /* If -2 was returned, no error message was printed */
                if (r == -2)
                    emsg ("[line %d] invalid configuration file", line);

                return -1;
            }
        }
    }

    return 0;
}


/* -----------------------------------------------------------------------------
 * CALLBACKS
 */

int
op_sysctlconfig (struct snmp_context *ctx, struct snmp_value *value,
                u_int sub, u_int iidx, enum snmp_op op)
{
    asn_subid_t which = value->var.subs[sub - 1];
    int r = SNMP_ERR_NOERROR;

    (void)iidx;

    switch (which) {
    case LEAF_sysctlConfig:

        if (op == SNMP_OP_GET)
            return string_get (value, sysctl_config, -1);

        /* Remainder only at initialization */
        if (community != COMM_INITIALIZE)
            return SNMP_ERR_NOT_WRITEABLE;

        switch (op) {
        case SNMP_OP_SET:
            if ((r = string_save (value, ctx, -1, &sysctl_config)) == SNMP_ERR_NOERROR) {
                if (!sysctl_config[0])
                    r = SNMP_ERR_WRONG_VALUE;
                else if (config_parse () < 0)
                    r = SNMP_ERR_GENERR;
            }
            if (r != SNMP_ERR_NOERROR)
                string_rollback (ctx, &sysctl_config);
            break;
        case SNMP_OP_COMMIT:
            string_commit (ctx);
            break;
        case SNMP_OP_ROLLBACK:
            string_rollback (ctx, &sysctl_config);
            break;
        default:
            ASSERT(0);
            break;
        }

        return r;

    }

    ASSERT(0);
    return -1;
}

int
op_sysctl (struct snmp_context *ctx, struct snmp_value *value,
          u_int sub, u_int iidx, enum snmp_op op)
{
    asn_subid_t which = value->var.subs[sub - 1];
    int stdval = 0x01234567;

    (void)ctx;
    (void)iidx;

    switch (op) {
    case SNMP_OP_GET:
        break;

    case SNMP_OP_SET:
        /* XXX - maybe in the future */
        return SNMP_ERR_NOT_WRITEABLE;

    case SNMP_OP_ROLLBACK:
    case SNMP_OP_COMMIT:
        return SNMP_ERR_NOERROR;

    default:
        ASSERT(0);
        break;
    }

    switch (which) {
    case LEAF_sysctlCount:
        value->v.integer = entry_count;
        break;

    case LEAF_sysctlEndian:
        return string_get(value, (char *)&stdval, sizeof stdval);
        break;

    default:
        ASSERT(0);
        break;
    }

    return SNMP_ERR_NOERROR;
}

#if 0
static int
strisprint(char *str, size_t buflen)
{

        while (buflen--) {
                if (!isprint(*str) && !isspace(*str))
                        return 0;
                str++;
        }

        return 1;
}
#endif

static char *
makehexstr(unsigned char *buf, size_t buflen)
{
        char *ostr, *str;

        ostr = str = malloc(buflen * 2 + 1);

        while (buflen--) {
                sprintf(str, "%02x", (unsigned)*buf++);
                str += 2;
        }

        str[0] = '\x00';

        return ostr;
}

int
op_sysctlentry (struct snmp_context *ctx, struct snmp_value *value,
             u_int sub, u_int iidx, enum snmp_op op)
{
    char buffer[512];
    asn_subid_t which = value->var.subs[sub - 1];
    struct data_entry *data;
    uint64_t ticks;
    size_t buflen;
    int fetch = 1;

    (void)ctx;

    switch (op) {
    case SNMP_OP_GETNEXT:
        data = NEXT_OBJECT_INT (&entries, &value->var, sub);
        if (data == NULL)
            return SNMP_ERR_NOSUCHNAME;
        value->var.len = sub + 1;
        value->var.subs[sub] = data->index;
        break;

    case SNMP_OP_GET:
        data = FIND_OBJECT_INT (&entries, &value->var, sub);
        if (data == NULL)
            return SNMP_ERR_NOSUCHNAME;
        break;

    case SNMP_OP_SET:
        if (index_decode (&value->var, sub, iidx, &data))
            return SNMP_ERR_NO_CREATION;
        data = FIND_OBJECT_INT (&entries, &value->var, sub);
        if (data != NULL)
            return SNMP_ERR_NOT_WRITEABLE;
        return SNMP_ERR_NO_CREATION;

    default:
        ASSERT(0);
        break;
    }

    /* Figure out if we should fetch or not */
    /* XXX - only fetch on value fetches? */
    ticks = getcurrticks ();
    if (ticks == 0)
        return SNMP_ERR_GENERR;
    if (data->cache && data->last_update) {
        if (ticks < (data->last_update + data->cache))
            fetch = 0;
    }

    if (fetch) {
        free(data->value_raw);
        data->value_raw = NULL;
        data->value_rawlen = 0;

        free(data->value_str);
        data->value_str = NULL;
        data->value_strlen = 0;

        /* XXX - oidfmt and friends from sysctl */
        /* XXX - length */
        buflen = sizeof buffer;
        if (sysctl(data->name, data->namelen, buffer, &buflen, NULL, 0) == -1) {
            data->error = errno;
            data->value_int = 0;
        } else {
            data->last_update = getcurrticks();
            data->error = 0;

            data->value_raw = malloc(buflen);
            data->value_rawlen = buflen;
            memcpy(data->value_raw, buffer, buflen);

            data->value_int = 0;

            emsg("test: buflen %d, sysctl: %s, ticks: %llu, lu: %llu", buflen, data->descr, ticks, data->last_update);

            if (strcmp("A", data->fmt) == 0) {
                data->value_str = malloc(buflen);
                strlcpy(data->value_str, buffer, buflen);
            } else if (strcmp("I", data->fmt) == 0) {
                data->value_int = *(int32_t *)buffer;
            } else {
                    data->value_str = makehexstr(buffer, buflen);
            }
        }
    }

    if (data->value_str == NULL)
            asprintf(&data->value_str, "%jd", (intmax_t)data->value_int);

    data->value_strlen = strlen(data->value_str);

    switch (which) {
    case LEAF_sysctlIndex:
        value->v.integer = data->index;
        break;

    case LEAF_sysctlDescr:
        return (string_get (value, data->descr, -1));

    case LEAF_sysctlType:
        value->v.uint32 = data->type;
        break;

    case LEAF_sysctlFmt:
        return (string_get (value, data->fmt, -1));

    case LEAF_sysctlErrno:
        value->v.uint32 = data->error;
        break;

    case LEAF_sysctlLast:
        if (data->last_update)
            value->v.uint32 = (ticks - data->last_update);
        else
            value->v.uint32 = 0;
        break;

    case LEAF_sysctlInteger:
        value->v.uint32 = data->value_int;
        break;

    case LEAF_sysctlValue:
        return string_get(value, data->value_str, data->value_strlen);

    case LEAF_sysctlRaw:
        return string_get(value, data->value_raw, data->value_rawlen);

    case LEAF_sysctlCounter:
        value->v.counter64 = data->value_int;
        break;

    default:
        ASSERT(0);
        break;
    };

    return SNMP_ERR_NOERROR;
}

/* -----------------------------------------------------------------------------
 * MODULE
 */

/* the initialisation function */
static int
module_init(struct lmodule *mod, int argc, char *argv[])
{

    (void)argv;

    module = mod;

    if (argc != 0) {
        syslog(LOG_ERR, "bad number of arguments for %s", __func__);
        return EINVAL;
    }

    sysctl_config = strdup(DEFAULT_CONFIG);
    if (!sysctl_config)
        return ENOMEM;

    return 0;
}

/* Module is started */
static void
module_start (void)
{
    reg_index = or_register (&oid_sysctl, "The MIB for sysctl data.", module);
}

/* Called, when the module is to be unloaded after it was successfully loaded */
static int
module_fini (void)
{
    if (reg_index)
        or_unregister (reg_index);

    ASSERT (sysctl_config);
    free (sysctl_config);

    config_free_all ();

    return 0;
}

const struct snmp_module config = {
    .comment =      "This module implements SNMP listing of data from sysctl.",
    .init =         module_init,
    .start =        module_start,
    .fini =         module_fini,
    .tree =         sysctl_ctree,
    .tree_size =    sysctl_CTREE_SIZE,
};