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Annotation of libwww/Library/src/HTEscape.c, revision 2.6

2.2       frystyk     1: /*                                                                  HTEscape.c
                      2: **     ESCAPE AND UNESACPE ILLEGAL CHARACTERS IN A URI
                      3: **
2.5       frystyk     4: **     (c) COPYRIGHT MIT 1995.
2.2       frystyk     5: **     Please first read the full copyright statement in the file COPYRIGH.
2.1       frystyk     6: **
                      7: ** history:
                      8: **     Nov 13 94       Spawned from HTParse, as it then can be used in utility
                      9: **                     programs without loading the whole library
                     10: */
                     11: 
2.4       frystyk    12: /* Library include files */
                     13: #include "tcp.h"
2.1       frystyk    14: #include "HTUtils.h"
                     15: #include "HTEscape.h"                                   /* Implemented here */
                     16: 
                     17: #define HEX_ESCAPE '%'
2.6     ! frystyk    18: #define ACCEPTABLE(a)  ( a>=32 && a<128 && ((isAcceptable[a-32]) & mask))
        !            19: 
        !            20: /*
        !            21: **  Not BOTH static AND const at the same time in gcc :-(, Henrik 18/03-94 
        !            22: **  code gen error in gcc when making random access to static const table(!!)
        !            23: */
        !            24: 
        !            25: /*
        !            26: **     Bit 0           xalpha          -- see HTFile.h
        !            27: **     Bit 1           xpalpha         -- as xalpha but with plus.
        !            28: **     Bit 2 ...       path            -- as xpalpha but with /
        !            29: */
        !            30: PRIVATE unsigned char isAcceptable[96] =
        !            31: {/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
        !            32:     0,0,0,0,0,0,0,0,0,0,7,6,0,7,7,4,           /* 2x   !"#$%&'()*+,-./  */
        !            33:     7,7,7,7,7,7,7,7,7,7,0,0,0,0,0,0,           /* 3x  0123456789:;<=>?  */
        !            34:     7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,           /* 4x  @ABCDEFGHIJKLMNO  */
        !            35:     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,7,           /* 5X  PQRSTUVWXYZ[\]^_  */
        !            36:     0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,           /* 6x  `abcdefghijklmno  */
        !            37:     7,7,7,7,7,7,7,7,7,7,7,0,0,0,0,0            /* 7X  pqrstuvwxyz{\}~  DEL */
        !            38: };
        !            39: PRIVATE char *hex = "0123456789ABCDEF";
2.1       frystyk    40: 
                     41: /* ------------------------------------------------------------------------- */
                     42: 
                     43: /*             Escape undesirable characters using %           HTEscape()
                     44: **             -------------------------------------
                     45: **
                     46: **     This function takes a pointer to a string in which
                     47: **     some characters may be unacceptable unescaped.
                     48: **     It returns a string which has these characters
                     49: **     represented by a '%' character followed by two hex digits.
                     50: **
                     51: **     In the tradition of being conservative in what you do and liberal
                     52: **     in what you accept, we encode some characters which in fact are
                     53: **     allowed in URLs unencoded -- so DON'T use the table below for
                     54: **     parsing! 
                     55: **
                     56: **     Unlike HTUnEscape(), this routine returns a malloced string.
                     57: **
                     58: */
2.6     ! frystyk    59: PUBLIC char * HTEscape (CONST char * str, HTURIEncoding mask)
2.1       frystyk    60: {
                     61:     CONST char * p;
                     62:     char * q;
                     63:     char * result;
                     64:     int unacceptable = 0;
                     65:     for(p=str; *p; p++)
                     66:         if (!ACCEPTABLE((unsigned char)TOASCII(*p)))
                     67:                unacceptable++;
                     68:     result = (char *) malloc(p-str + unacceptable+ unacceptable + 1);
                     69:     if (result == NULL) outofmem(__FILE__, "HTEscape");
                     70:     for(q=result, p=str; *p; p++) {
                     71:        unsigned char a = TOASCII(*p);
                     72:        if (!ACCEPTABLE(a)) {
                     73:            *q++ = HEX_ESCAPE;  /* Means hex commming */
                     74:            *q++ = hex[a >> 4];
                     75:            *q++ = hex[a & 15];
                     76:        }
                     77:        else *q++ = *p;
                     78:     }
                     79:     *q++ = 0;                  /* Terminate */
                     80:     return result;
                     81: }
                     82: 
                     83: 
                     84: /*             Decode %xx escaped characters                   HTUnEscape()
                     85: **             -----------------------------
                     86: **
                     87: **     This function takes a pointer to a string in which some
                     88: **     characters may have been encoded in %xy form, where xy is
                     89: **     the acsii hex code for character 16x+y.
                     90: **     The string is converted in place, as it will never grow.
                     91: */
                     92: 
                     93: PRIVATE char from_hex ARGS1(char, c)
                     94: {
                     95:     return  c >= '0' && c <= '9' ?  c - '0' 
                     96:            : c >= 'A' && c <= 'F'? c - 'A' + 10
                     97:            : c - 'a' + 10;     /* accept small letters just in case */
                     98: }
                     99: 
                    100: PUBLIC char * HTUnEscape ARGS1( char *, str)
                    101: {
                    102:     char * p = str;
                    103:     char * q = str;
                    104: 
                    105:     if (!str) {                                              /* Just for safety ;-) */
                    106:        if (URI_TRACE)
2.4       frystyk   107:            fprintf(TDEST, "HTUnEscape.. Called with NULL argument.\n");
2.1       frystyk   108:        return "";
                    109:     }
                    110:     while(*p) {
                    111:         if (*p == HEX_ESCAPE) {
                    112:            p++;
                    113:            if (*p) *q = from_hex(*p++) * 16;
                    114:            if (*p) *q = FROMASCII(*q + from_hex(*p++));
                    115:            q++;
                    116:        } else {
                    117:            *q++ = *p++; 
                    118:        }
                    119:     }
                    120:     
                    121:     *q++ = 0;
                    122:     return str;
                    123:     
                    124: } /* HTUnEscape */
                    125: