/*
 * Copyright (c) 2016 MariaDB Corporation Ab
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
 *
 * Change Date: 2020-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2 or later of the General
 * Public License.
 */


/**
 * @file mysql_utils.c  - Binary MySQL data processing utilities
 *
 * This file contains functions that are used when processing binary format
 * information. The MySQL protocol uses the binary format in result sets and
 * row based replication.
 */

#include <maxscale/mysql_utils.h>

#include <string.h>
#include <strings.h>
#include <stdbool.h>
#include <errmsg.h>

#include <maxscale/alloc.h>
#include <maxscale/config.h>
#include <maxscale/debug.h>
#include <maxscale/log_manager.h>

namespace
{

struct THIS_UNIT
{
    bool log_statements; // Should all statements sent to server be logged?
};

static THIS_UNIT this_unit =
{
    false
};

}

/**
 * @brief Calculate the length of a length-encoded integer in bytes
 *
 * @param ptr Start of the length encoded value
 * @return Number of bytes before the actual value
 */
size_t mxs_leint_bytes(const uint8_t* ptr)
{
    uint8_t val = *ptr;
    if (val < 0xfb)
    {
        return 1;
    }
    else if (val == 0xfc)
    {
        return 3;
    }
    else if (val == 0xfd)
    {
        return 4;
    }
    else
    {
        return 9;
    }
}

/**
 * @brief Converts a length-encoded integer to @c uint64_t
 *
 * @see https://dev.mysql.com/doc/internals/en/integer.html
 * @param c Pointer to the first byte of a length-encoded integer
 * @return The value converted to a standard unsigned integer
 */
uint64_t mxs_leint_value(const uint8_t* c)
{
    uint64_t sz = 0;

    if (*c < 0xfb)
    {
        sz = *c;
    }
    else if (*c == 0xfc)
    {
        memcpy(&sz, c + 1, 2);
    }
    else if (*c == 0xfd)
    {
        memcpy(&sz, c + 1, 3);
    }
    else if (*c == 0xfe)
    {
        memcpy(&sz, c + 1, 8);
    }
    else
    {
        ss_dassert(*c == 0xff);
        MXS_ERROR("Unexpected length encoding '%x' encountered when reading "
                  "length-encoded integer.", *c);
    }

    return sz;
}

/**
 * Converts a length-encoded integer into a standard unsigned integer
 * and advances the pointer to the next unrelated byte.
 *
 * @param c Pointer to the first byte of a length-encoded integer
 */
uint64_t mxs_leint_consume(uint8_t ** c)
{
    uint64_t rval = mxs_leint_value(*c);
    *c += mxs_leint_bytes(*c);
    return rval;
}

/**
 * @brief Consume and duplicate a length-encoded string
 *
 * Converts a length-encoded string to a C string and advances the pointer to
 * the first byte after the string. The caller is responsible for freeing
 * the returned string.
 * @param c Pointer to the first byte of a valid packet.
 * @return The newly allocated string or NULL if memory allocation failed
 */
char* mxs_lestr_consume_dup(uint8_t** c)
{
    uint64_t slen = mxs_leint_consume(c);
    char *str = (char*)MXS_MALLOC((slen + 1) * sizeof(char));

    if (str)
    {
        memcpy(str, *c, slen);
        str[slen] = '\0';
        *c += slen;
    }

    return str;
}

/**
 * @brief Consume a length-encoded string
 *
 * Converts length-encoded strings to character strings and advanced
 * the pointer to the next unrelated byte.
 * @param c Pointer to the start of the length-encoded string
 * @param size Pointer to a variable where the size of the string is stored
 * @return Pointer to the start of the string
 */
char* mxs_lestr_consume(uint8_t** c, size_t *size)
{
    uint64_t slen = mxs_leint_consume(c);
    *size = slen;
    char* start = (char*) *c;
    *c += slen;
    return start;
}

MYSQL *mxs_mysql_real_connect(MYSQL *con, SERVER *server, const char *user, const char *passwd)
{
    SSL_LISTENER *listener = server->server_ssl;

    if (listener)
    {
        mysql_ssl_set(con, listener->ssl_key, listener->ssl_cert, listener->ssl_ca_cert, NULL, NULL);
    }

    char yes = 1;
    mysql_optionsv(con, MYSQL_OPT_RECONNECT, &yes);
    mysql_optionsv(con, MYSQL_INIT_COMMAND, "SET SQL_MODE=''");

    MXS_CONFIG* config = config_get_global_options();

    if (config->local_address)
    {
        if (mysql_optionsv(con, MYSQL_OPT_BIND, config->local_address) != 0)
        {
            MXS_ERROR("'local_address' specified in configuration file, but could not "
                      "configure MYSQL handle. MaxScale will try to connect using default "
                      "address.");
        }
    }

    MYSQL* mysql = mysql_real_connect(con, server->name, user, passwd, NULL, server->port, NULL, 0);

    if (mysql)
    {
        /** Copy the server charset */
        MY_CHARSET_INFO cs_info;
        mysql_get_character_set_info(mysql, &cs_info);
        server->charset = cs_info.number;

        if (listener && mysql_get_ssl_cipher(con) == NULL)
        {
            if (server->log_warning.ssl_not_enabled)
            {
                server->log_warning.ssl_not_enabled = false;
                MXS_ERROR("An encrypted connection to '%s' could not be created, "
                          "ensure that TLS is enabled on the target server.",
                          server->unique_name);
            }
            // Don't close the connection as it is closed elsewhere, just set to NULL
            mysql = NULL;
        }
    }

    return mysql;
}

static bool is_connection_error(int errcode)
{
    switch (errcode)
    {
        case CR_SOCKET_CREATE_ERROR:
        case CR_CONNECTION_ERROR:
        case CR_CONN_HOST_ERROR:
        case CR_IPSOCK_ERROR:
        case CR_SERVER_GONE_ERROR:
        case CR_TCP_CONNECTION:
        case CR_SERVER_LOST:
            return true;

        default:
            return false;
    }
}

int mxs_mysql_query(MYSQL* conn, const char* query)
{
    MXS_CONFIG* cnf = config_get_global_options();
    time_t start = time(NULL);
    int rc = mysql_query(conn, query);

    for (int n = 0; rc != 0 && n < cnf->query_retries &&
         is_connection_error(mysql_errno(conn)) &&
         time(NULL) - start < cnf->query_retry_timeout; n++)
    {
        rc = mysql_query(conn, query);
    }

    if (this_unit.log_statements)
    {
        const char* host;
        if (mariadb_get_info(conn, MARIADB_CONNECTION_HOST, &host) != 0)
        {
            // No idea about the host, but let's use something that looks like
            // an IP-address as a placeholder.
            host = "0.0.0.0";
        }

        MXS_NOTICE("SQL(%s): %d, \"%s\"", host, rc, query);
    }

    return rc;
}

const char* mxs_mysql_get_value(MYSQL_RES* result, MYSQL_ROW row, const char* key)
{
    MYSQL_FIELD* f = mysql_fetch_fields(result);
    int nfields = mysql_num_fields(result);

    for (int i = 0; i < nfields; i++)
    {
        if (strcasecmp(f[i].name, key) == 0)
        {
            return row[i];
        }
    }

    return NULL;
}

bool mxs_mysql_trim_quotes(char *s)
{
    bool dequoted = true;

    char *i = s;
    char *end = s + strlen(s);

    // Remove space from the beginning
    while (*i && isspace(*i))
    {
        ++i;
    }

    if (*i)
    {
        // Remove space from the end
        while (isspace(*(end - 1)))
        {
            *(end - 1) = 0;
            --end;
        }

        ss_dassert(end > i);

        char quote;

        switch (*i)
        {
        case '\'':
        case '"':
        case '`':
            quote = *i;
            ++i;
            break;

        default:
            quote = 0;
        }

        if (quote)
        {
            --end;

            if (*end == quote)
            {
                *end = 0;

                memmove(s, i, end - i + 1);
            }
            else
            {
                dequoted = false;
            }
        }
        else if (i != s)
        {
            memmove(s, i, end - i + 1);
        }
    }
    else
    {
        *s = 0;
    }

    return dequoted;
}


mxs_mysql_name_kind_t mxs_mysql_name_to_pcre(char *pcre,
                                             const char *mysql,
                                             mxs_pcre_quote_approach_t approach)
{
    mxs_mysql_name_kind_t rv = MXS_MYSQL_NAME_WITHOUT_WILDCARD;

    while (*mysql)
    {
        switch (*mysql)
        {
        case '%':
            if (approach == MXS_PCRE_QUOTE_WILDCARD)
            {
                *pcre = '.';
                pcre++;
                *pcre = '*';
            }
            rv = MXS_MYSQL_NAME_WITH_WILDCARD;
            break;

        case '\'':
        case '^':
        case '.':
        case '$':
        case '|':
        case '(':
        case ')':
        case '[':
        case ']':
        case '*':
        case '+':
        case '?':
        case '{':
        case '}':
            *pcre++ = '\\';
        // Flowthrough
        default:
            *pcre = *mysql;
        }

        ++pcre;
        ++mysql;
    }

    *pcre = 0;

    return rv;
}

void mxs_mysql_set_server_version(MYSQL* mysql, SERVER* server)
{
    const char* version_string = mysql_get_server_info(mysql);

    if (version_string)
    {
        unsigned long version = mysql_get_server_version(mysql);

        server_set_version(server, version_string, version);
    }
}

void mxs_mysql_set_log_statements(bool enable)
{
    this_unit.log_statements = enable;
}

bool mxs_mysql_get_log_statements()
{
    return this_unit.log_statements;
}