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much shorter way to do the same thing

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This commit is contained in:
leitner 2014-04-15 20:36:50 +00:00
parent 708c358a74
commit cf1406735c
1 changed files with 5 additions and 19 deletions
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24
scan/scan_asn1dertag.c
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@ -2,25 +2,10 @@
size_t scan_asn1dertag(const char* src,size_t len,unsigned long long* length) { size_t scan_asn1dertag(const char* src,size_t len,unsigned long long* length) {
size_t n; size_t n;
unsigned long long l; unsigned long long l=0;
unsigned int bits=0; if (len==0 || (unsigned char)src[0]==0x80) return 0; // catch non-minimal encoding
if (len==0) return 0; for (n=0; n<len; ++n) {
{ if (l>>(sizeof(l)*8-7)) return 0; // catch integer overflow
unsigned int k=src[0]&0x7f;
if (!(src[0]&0x80)) {
*length=k;
return 1;
}
if (!(l=k)) return 0; // non-minimal encoding
while (k) { // count bits in leading byte
++bits;
k>>=1;
}
bits=sizeof(l)*8-bits;
}
for (n=1; n<len; ++n) {
if (bits<7) return 0;
bits-=7;
l=(l<<7) | (src[n]&0x7f); l=(l<<7) | (src[n]&0x7f);
if (!(src[n]&0x80)) { if (!(src[n]&0x80)) {
*length=l; *length=l;
@ -29,3 +14,4 @@ size_t scan_asn1dertag(const char* src,size_t len,unsigned long long* length) {
} }
return 0; return 0;
} }