f0577d8ea0
The functions encode and decode are now capable of processing larger buffers with less conditional logic. Input and output functions need to follow suit to make better use of this next. Encode without line wrapping already makes use of these improvements, because input and output are now entirely handled by <stdio.h> functions.
103 lines
2.6 KiB
C
103 lines
2.6 KiB
C
#include "encode.h"
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#define PADDING '='
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unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"+/";
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unsigned char b64url[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"-_";
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int
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encode(unsigned char *op, int olen, unsigned char *sp, int url)
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{
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int tmp;
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unsigned char *table;
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unsigned char *sbeg;
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unsigned char *tend;
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table = (!url) ? b64 : b64url;
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sbeg = sp;
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tend = op + olen - (olen % 3);
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while (op < tend) {
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*sp++ = table[(*op & ~3) >> 2];
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tmp = (*op++ & 3) << 4;
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*sp++ = table[tmp + ((*op & ~15) >> 4)];
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tmp = (*op++ & 15) << 2;
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*sp++ = table[tmp + ((*op & 192) >> 6)];
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*sp++ = table[*op++ & ~192];
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}
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switch (olen % 3) {
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case 2:
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*sp++ = table[(*op & ~3) >> 2];
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tmp = (*op++ & 3) << 4;
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*sp++ = table[tmp + ((*op & ~15) >> 4)];
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*sp++ = table[(*op & 15) << 2];
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*sp++ = PADDING;
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break;
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case 1:
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*sp++ = table[(*op & ~3) >> 2];
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*sp++ = table[(*op & 3) << 4];
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*sp++ = PADDING;
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*sp++ = PADDING;
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break;
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}
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return sp-sbeg;
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}
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int
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decode(unsigned char *sp, int slen, unsigned char *op, int url)
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{
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int tmp, b, atob(int c, int url);
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unsigned char *obeg;
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unsigned char *qend;
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obeg = op;
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qend = sp + slen - (slen % 4);
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while (sp < qend) {
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tmp = atob(*sp++, url) << 2;
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b = atob(*sp++, url);
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*op++ = tmp + ((b & ~15) >> 4);
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tmp = (b & 15) << 4;
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b = atob(*sp++, url);
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*op++ = tmp + ((b & ~3) >> 2);
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*op++ = ((b & 3) << 6) + atob(*sp++, url);
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}
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switch (slen % 4) {
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case 3:
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tmp = atob(*sp++, url) << 2;
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b = atob(*sp++, url);
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*op++ = tmp + ((b & ~15) >> 4);
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tmp = (b & 15) << 4;
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*op++ = tmp + ((atob(*sp++, url) & ~3) >> 2);
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break;
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case 2:
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tmp = atob(*sp++, url) << 2;
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*op++ = tmp + ((atob(*sp++, url) & ~15) >> 4);
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break;
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}
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return op-obeg;
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}
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int atob(int c, int url)
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{
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if (c >= 'A' && c <= 'Z')
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c -= 'A';
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else if (c >= 'a' && c <= 'z')
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c = c - 'a' + 26;
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else if (c >= '0' && c <= '9')
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c = c - '0' + 26 * 2;
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else if (c == ((!url) ? '+' : '-'))
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c = 62;
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else
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c = 63;
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return c;
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}
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