snort_ftptelnet.c

Snort为国际上著名的轻量型入侵防御系统,为国内多家著名“自主知识产权”网络安全公司所使用。

        pcToken = NextToken( CONF_SEPARATORS);
        if(!pcToken)
        {
            snprintf(ErrorString, ErrStrLen,
                    "Invalid cmd list format.");

            return FTPP_FATAL_ERR;
        }

        iLength = strtol(pcToken, &pcEnd, 10);

        /*
         * Let's check to see if the entire string was valid.
         * If there is an address here, then there was an
         * invalid character in the string.
         */
        if((*pcEnd) || (iLength < 0))
        {
            snprintf(ErrorString, ErrStrLen,
                    "Invalid argument to token '%s'.  "
                    "Length must be a positive number",
                    confOption);

            return FTPP_FATAL_ERR;
        }
    }

    if (require_cmds)
    {
        pcToken = NextToken( CONF_SEPARATORS);
        if(!pcToken)
        {
            snprintf(ErrorString, ErrStrLen,
                    "Invalid cmd list format.");

            return FTPP_FATAL_ERR;
        }

        if(strcmp(START_PORT_LIST, pcToken))
        {
            snprintf(ErrorString, ErrStrLen,
                    "Must start a cmd list with the '%s' token.",
                    START_PORT_LIST);

            return FTPP_FATAL_ERR;
        }
    
        while((pcToken = NextToken( CONF_SEPARATORS)))
        {
            if(!strcmp(END_PORT_LIST, pcToken))
            {
                iEndCmds = 1;
                break;
            }

            cmd = pcToken;

            if (strlen(cmd) > 4)
            {
                snprintf(ErrorString, ErrStrLen,
                        "FTP Commands are no longer than 4 characters: '%s'.",
                        cmd);

                return FTPP_FATAL_ERR;
            }

            FTPCmd = ftp_cmd_lookup_find(ServerConf->cmd_lookup, cmd,
                                         strlen(cmd), &iRet);

            if (FTPCmd == NULL)
            {
                /* Add it to the list  */
                FTPCmd = (FTP_CMD_CONF *)malloc(sizeof(FTP_CMD_CONF));
                memset(FTPCmd, 0, sizeof(FTP_CMD_CONF));
                strcpy(FTPCmd->cmd_name, cmd);

                ftp_cmd_lookup_add(ServerConf->cmd_lookup, cmd,
                                   strlen(cmd), FTPCmd);
                FTPCmd->max_param_len = ServerConf->def_max_param_len;
            }

            if (require_length)
            {
                FTPCmd->max_param_len = iLength;
                FTPCmd->max_param_len_overridden = 1;
            }
        }

        if(!iEndCmds)
        {
            snprintf(ErrorString, ErrStrLen,
                    "Must end '%s' configuration with '%s'.",
                    FTP_CMDS, END_PORT_LIST);

            return FTPP_FATAL_ERR;
        }
    }

    if (!strcmp(confOption, MAX_PARAM_LEN))
    {
        ServerConf->def_max_param_len = iLength;
        /* Reset the max length to the default for all existing commands  */
        FTPCmd = ftp_cmd_lookup_first(ServerConf->cmd_lookup, &iRet);
        while (FTPCmd)
        {
            if (!FTPCmd->max_param_len_overridden)
            {
                FTPCmd->max_param_len = ServerConf->def_max_param_len;
            }
            FTPCmd = ftp_cmd_lookup_next(ServerConf->cmd_lookup, &iRet);
        }
    }

    return FTPP_SUCCESS;
}

/*
 * Function: ResetStringFormat (FTP_PARAM_FMT *Fmt)
 *
 * Purpose: Recursively sets nodes that allow strings to nodes that check
 *          for a string format attack within the FTP parameter validation tree
 *
 * Arguments: Fmt       => pointer to the FTP Parameter configuration
 *
 * Returns: None
 *
 */
void ResetStringFormat (FTP_PARAM_FMT *Fmt)
{
    int i;
    if (!Fmt)
        return;

    if (Fmt->type == e_unrestricted)
        Fmt->type = e_strformat;

    ResetStringFormat(Fmt->optional_fmt);
    for (i=0;i<Fmt->numChoices;i++)
    {
        ResetStringFormat(Fmt->choices[i]);
    }
    ResetStringFormat(Fmt->next_param_fmt);
}

/*
 * Function: ProcessFTPDataChanCmdsList(FTP_SERVER_PROTO_CONF *ServerConf,
 *                             char *confOption,
 *                             char *ErrorString, int ErrStrLen)
 *
 * Purpose: Process the FTP cmd lists for the client configuration.
 *          This configuration is an indicator of data channels, data transfer,
 *          string format, encryption, or login commands.
 *
 * Arguments: ServerConf    => pointer to the FTP server configuration
 *            confOption    => pointer to the name of the option
 *            ErrorString   => error string buffer
 *            ErrStrLen     => the length of the error string buffer
 *
 * Returns: int     => an error code integer (0 = success,
 *                     >0 = non-fatal error, <0 = fatal error)
 *
 */
static int ProcessFTPDataChanCmdsList(FTP_SERVER_PROTO_CONF *ServerConf,
                                      char *confOption, 
                                      char *ErrorString, int ErrStrLen)
{
    FTP_CMD_CONF *FTPCmd = NULL;
    char *pcToken;
    char *cmd;
    int  iEndCmds = 0;
    int  iRet;

    pcToken = NextToken( CONF_SEPARATORS);
    if(!pcToken)
    {
        snprintf(ErrorString, ErrStrLen,
                "Invalid %s list format.", confOption);

        return FTPP_FATAL_ERR;
    }

    if(strcmp(START_PORT_LIST, pcToken))
    {
        snprintf(ErrorString, ErrStrLen,
                "Must start a %s list with the '%s' token.",
                confOption, START_PORT_LIST);

        return FTPP_FATAL_ERR;
    }
    
    while((pcToken = NextToken( CONF_SEPARATORS)))
    {
        if(!strcmp(END_PORT_LIST, pcToken))
        {
            iEndCmds = 1;
            break;
        }

        cmd = pcToken;

        if (strlen(cmd) > 4)
        {
            snprintf(ErrorString, ErrStrLen,
                    "FTP Commands are no longer than 4 characters: '%s'.",
                    cmd);

            return FTPP_FATAL_ERR;
        }

        FTPCmd = ftp_cmd_lookup_find(ServerConf->cmd_lookup, cmd,
                                     strlen(cmd), &iRet);

        if (FTPCmd == NULL)
        {
            /* Add it to the list  */
            FTPCmd = (FTP_CMD_CONF *)malloc(sizeof(FTP_CMD_CONF));
            memset(FTPCmd, 0, sizeof(FTP_CMD_CONF));
            strcpy(FTPCmd->cmd_name, cmd);
            FTPCmd->max_param_len = ServerConf->def_max_param_len;

            ftp_cmd_lookup_add(ServerConf->cmd_lookup, cmd,
                               strlen(cmd), FTPCmd);
        }

        if (!strcmp(confOption, DATA_CHAN_CMD))
            FTPCmd->data_chan_cmd = 1;
        else if (!strcmp(confOption, DATA_XFER_CMD))
            FTPCmd->data_xfer_cmd = 1;
        else if (!strcmp(confOption, STRING_FORMAT))
        {
            FTP_PARAM_FMT *Fmt = FTPCmd->param_format;
            if (Fmt)
            {
                ResetStringFormat(Fmt);
            }
            else
            {
                Fmt = malloc(sizeof(FTP_PARAM_FMT));
                memset(Fmt, 0, sizeof(FTP_PARAM_FMT));
                Fmt->type = e_head;
                FTPCmd->param_format = Fmt;
                Fmt = malloc(sizeof(FTP_PARAM_FMT));
                memset(Fmt, 0, sizeof(FTP_PARAM_FMT));
                Fmt->type = e_strformat;
                FTPCmd->param_format->next_param_fmt = Fmt;
                Fmt->prev_param_fmt = FTPCmd->param_format;
            }
            FTPCmd->check_validity = 1;
        }
        else if (!strcmp(confOption, ENCR_CMD))
            FTPCmd->encr_cmd = 1;
        else if (!strcmp(confOption, LOGIN_CMD))
            FTPCmd->login_cmd = 1;
    }

    if(!iEndCmds)
    {
        snprintf(ErrorString, ErrStrLen,
                "Must end '%s' configuration with '%s'.",
                confOption, END_PORT_LIST);

        return FTPP_FATAL_ERR;
    }

    return FTPP_SUCCESS;
}

/*
 * Function: ProcessFTPDirCmdsList(FTP_SERVER_PROTO_CONF *ServerConf,
 *                             char *confOption,
 *                             char *ErrorString, int ErrStrLen)
 *
 * Purpose: Process the FTP cmd lists for the client configuration.
 *          This configuration is an indicator of commands used to
 *          retrieve or update the current directory.
 *
 * Arguments: ServerConf    => pointer to the FTP server configuration
 *            confOption    => pointer to the name of the option
 *            ErrorString   => error string buffer
 *            ErrStrLen     => the length of the error string buffer
 *
 * Returns: int     => an error code integer (0 = success,
 *                     >0 = non-fatal error, <0 = fatal error)
 *
 */
static int ProcessFTPDirCmdsList(FTP_SERVER_PROTO_CONF *ServerConf,
                                 char *confOption, 
                                 char *ErrorString, int ErrStrLen)
{
    FTP_CMD_CONF *FTPCmd = NULL;
    char *pcToken;
    char *pcEnd = NULL;
    char *cmd;
    int  iCode;
    int  iEndCmds = 0;
    int  iRet;

    pcToken = NextToken( CONF_SEPARATORS);
    if(!pcToken)
    {
        snprintf(ErrorString, ErrStrLen,
                "Invalid %s list format.", confOption);

        return FTPP_FATAL_ERR;
    }

    if(strcmp(START_PORT_LIST, pcToken))
    {
        snprintf(ErrorString, ErrStrLen,
                "Must start a %s list with the '%s' token.",
                confOption, START_PORT_LIST);

        return FTPP_FATAL_ERR;
    }
    
    while((pcToken = NextToken( CONF_SEPARATORS)))
    {
        if(!strcmp(END_PORT_LIST, pcToken))
        {
            iEndCmds = 1;
            break;
        }

        cmd = pcToken;

        if (strlen(cmd) > 4)
        {
            snprintf(ErrorString, ErrStrLen,
                    "FTP Commands are no longer than 4 characters: '%s'.",
                    cmd);

            return FTPP_FATAL_ERR;
        }

        FTPCmd = ftp_cmd_lookup_find(ServerConf->cmd_lookup, cmd,
                                     strlen(cmd), &iRet);

        if (FTPCmd == NULL)
        {
            /* Add it to the list  */
            FTPCmd = (FTP_CMD_CONF *)malloc(sizeof(FTP_CMD_CONF));
            memset(FTPCmd, 0, sizeof(FTP_CMD_CONF));
            strcpy(FTPCmd->cmd_name, cmd);
            FTPCmd->max_param_len = ServerConf->def_max_param_len;

            ftp_cmd_lookup_add(ServerConf->cmd_lookup, cmd,
                               strlen(cmd), FTPCmd);
        }

        pcToken = NextToken( CONF_SEPARATORS);

        if (!pcToken)
        {
            snprintf(ErrorString, ErrStrLen,
                    "FTP Dir Cmds must have associated response code: '%s'.",
                    cmd);

            return FTPP_FATAL_ERR;
        }

        iCode = strtol(pcToken, &pcEnd, 10);

        /*
         * Let's check to see if the entire string was valid.
         * If there is an address here, then there was an
         * invalid character in the string.
         */
        if((*pcEnd) || (iCode < 0))
        {
            snprintf(ErrorString, ErrStrLen,
                    "Invalid argument to token '%s'.  "
                    "Code must be a positive number",
                    confOption);

            return FTPP_FATAL_ERR;
        }

        FTPCmd->dir_response = iCode;
    }

    if(!iEndCmds)
    {
        snprintf(ErrorString, ErrStrLen,
                "Must end '%s' configuration with '%s'.",
                confOption, END_PORT_LIST);

        return FTPP_FATAL_ERR;
    }

    return FTPP_SUCCESS;
}

/*
 * Function: SetOptionalsNext(FTP_PARAM_FMT *ThisFmt,
 *                            FTP_PARAM_FMT *NextFmt,
 *                            FTP_PARAM_FMT **choices,
 *                            int numChoices)
 *
 * Purpose: Recursively updates the next value for nodes in the FTP
 *          Parameter validation tree.
 *
 * Arguments: ThisFmt       => pointer to an FTP parameter validation node
 *            NextFmt       => pointer to an FTP parameter validation node
 *            choices       => pointer to a list of FTP parameter
 *                             validation nodes
 *            numChoices    => the number of nodes in the list
 *
 * Returns: int     => an error code integer (0 = success,
 *                     >0 = non-fatal error, <0 = fatal error)
 *
 */
static void SetOptionalsNext(FTP_PARAM_FMT *ThisFmt, FTP_PARAM_FMT *NextFmt,
                             FTP_PARAM_FMT **choices, int numChoices)
{
    if (!ThisFmt)
        return;

    if (ThisFmt->optional)
    {
        if (ThisFmt->next_param_fmt == NULL)
        {
            ThisFmt->next_param_fmt = NextFmt;
            if (numChoices)
            {
                ThisFmt->numChoices = numChoices;
                ThisFmt->choices = malloc(sizeof(FTP_PARAM_FMT *) *
                                          numChoices);
                memcpy(ThisFmt->choices, choices,
                    sizeof(FTP_PARAM_FMT *) * numChoices);
            }
        }
        else
        {
            SetOptionalsNext(ThisFmt->next_param_fmt, NextFmt,
                choices, numChoices);
        }
    }
    else
    {
        int i;
        SetOptionalsNext(ThisFmt->optional_fmt, ThisFmt->next_param_fmt,
            ThisFmt->choices, ThisFmt->numChoices);
        for (i=0;i<ThisFmt->numChoices;i++)
        {
            SetOptionalsNext(ThisFmt->choices[i], ThisFmt,
                choices, numChoices);
        }
        SetOptionalsNext(ThisFmt->next_param_fmt, ThisFmt,
            choices, numChoices);
    }