qvalue.c

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/*
 * $Id: qvalue.c,v 1.2 2005/02/18 18:16:48 janakj Exp $
 *
 * Handling of the q value
 *
 * Copyright (C) 2004 FhG FOKUS
 *
 * This file is part of ser, a free SIP server.
 *
 * ser is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * For a license to use the ser software under conditions
 * other than those described here, or to purchase support for this
 * software, please contact iptel.org by e-mail at the following addresses:
 *    info@iptel.org
 *
 * ser is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History
 * ------
 * 2004-04-25 created (janakj)
 */

#include "error.h"
#include "qvalue.h"


/*
 * Convert string representation of q parameter in qvalue_t
 */
int str2q(qvalue_t* q, char* s, int len)
{
        int i, digits, order;

             /* States and equivalent regular expressions of input */
        enum {
                ST_START,   /* (SPC|TAB)* */
                ST_0,       /* 0+ */
                ST_1,       /* 1 */
                ST_0_PT,    /* 0*\. */
                ST_1_PT,    /* 1\. */
                ST_1_PT_0,  /* 1\.0+ */
                ST_0_PT_N   /* 0*\.[0-9]+ */
        } state = ST_START;

        if (!q || !s) {
                return E_INVALID_PARAMS;
        }

        digits = 1;
        order = 100;
        for(i = 0; i < len; i++) {
                switch(state) {
                case ST_START:
                        switch(s[i]) {
                        case ' ':
                        case '\t':
                                break;

                        case '0':
                                *q = 0;
                                state = ST_0;
                                break;

                        case '1':
                                *q = 1000;
                                state = ST_1;
                                break;

                        case '.':
                                state = ST_0_PT;
                                break;

                        default:
                                return E_Q_INV_CHAR;
                        }
                        break;

                case ST_0:
                        switch(s[i]) {
                        case '0':
                                break;

                        case '.':
                                state = ST_0_PT;
                                break;

                        case '1':
                                *q = 1000;
                                state = ST_1;
                                break;

                        default:
                                if (s[i] >= '2' && s[i] <= '9') {
                                        return E_Q_TOO_BIG;
                                } else {
                                        return E_Q_INV_CHAR;
                                }
                        }
                        break;

                case ST_1:
                        if (s[i] == '.') {
                                state = ST_1_PT;
                                break;
                        } else {
                                if (s[i] >= '0' && s[i] <= '9') {
                                        return E_Q_TOO_BIG;
                                } else {
                                        return E_Q_INV_CHAR;
                                }
                        }
                        break;

                case ST_0_PT:
                        if (s[i] >= '0' && s[i] <= '9') {
                                *q =  (s[i] - '0') * order;
                                order /= 10;
                                state = ST_0_PT_N;
                        } else {
                                return E_Q_INV_CHAR;
                        }
                        break;

                case ST_1_PT:
                        if (s[i] == '0') {
                                state = ST_1_PT_0;
                        } else {
                                if (s[i] >= '1' && s[i] <= '9') {
                                        return E_Q_TOO_BIG;
                                } else {
                                        return E_Q_INV_CHAR;
                                }
                        }
                        break;

                case ST_1_PT_0:
                        if (s[i] == '0') {
                                break;
                        } else {
                                if (s[i] >= '1' && s[i] <= '9') {
                                        return E_Q_TOO_BIG;
                                } else {
                                        return E_Q_INV_CHAR;
                                }
                        }
                        break;

                case ST_0_PT_N:
                        if (s[i] >= '0' && s[i] <= '9') {
                                if (digits <= 3) {
                                        *q += (s[i] - '0') * order;
                                        order /= 10;
                                        digits++;
                                }
                        } else {
                                return E_Q_INV_CHAR;
                        }
                        break;
                }
        }

        switch(state) {
        case ST_START:
                return E_Q_EMPTY;
                
        case ST_0_PT:
        case ST_1_PT:
                return E_Q_DEC_MISSING;
                
        default:
                return 0;
        }
}

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