42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
#include "asn1.h"
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static size_t tagintlen(unsigned long l) {
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size_t i;
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size_t needed=((sizeof l)*8)/7+1;
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for (i=1; i<needed; ++i)
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if (!(l>>(i*7)))
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break;
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return i;
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}
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/* Common integer storing method, used in tags >= 0x1f and OIDs */
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/* Store big endian, 7 bits at a time, set high bit in all but last byte */
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/* Return number of bytes needed. Only write if dest!=NULL */
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size_t fmt_asn1tagint(char* dest,unsigned long l) {
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size_t bytes = tagintlen(l);
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if (dest) {
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size_t i, j=bytes, k=bytes;
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for (i=0; i<k; ++i) {
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--j;
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dest[i]=((l>>(j*7))&0x7f) + (j?0x80:0);
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}
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}
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return bytes;
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}
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#ifdef UNITTEST
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#include <assert.h>
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#include <string.h>
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int main() {
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char buf[10];
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assert(tagintlen(0xfffffffful)==5);
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assert(fmt_asn1tagint(buf,0xfffffffful)==5 && !memcmp(buf,"\x8f\xff\xff\xff\x7f",5));
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if (sizeof(long)==8) assert(fmt_asn1tagint(buf,0xfffffffffffffffful)==10 && !memcmp(buf,"\x81\xff\xff\xff\xff\xff\xff\xff\xff\x7f",10));
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assert(fmt_asn1tagint(buf,1)==1 && !memcmp(buf,"\x01",1));
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assert(fmt_asn1tagint(buf,0x7f)==1 && !memcmp(buf,"\x7f",1));
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assert(fmt_asn1tagint(buf,0x80)==2 && !memcmp(buf,"\x81\x00",2));
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assert(fmt_asn1tagint(buf,0xffffffff)==5 && !memcmp(buf,"\x8f\xff\xff\xff\x7f",5));
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}
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#endif
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