scan_asn1dertag - decode an unsigned integer from ASN.1 DER length encoding

       scan_asn1dertag  decodes  an unsigned integer in ASN.1 DER tag encoding from a memory area holding binary
       data.  It writes the decode value in dest and returns the number of bytes it read from src.

       scan_asn1dertag never reads more than len bytes from src.  If the sequence is longer than  that,  or  the
       memory area contains an invalid sequence, scan_asn1dertag returns 0 and does not touch dest.

       The  length  of  the longest ASN.1 DER length sequence is 128 bytes.  In practice the largest sequence is
       sizeof(*dest)+1.

       scan_asn1dertag - decode an unsigned integer from ASN.1 DER length encoding

fmt_asn1dertag(3)

                                                                                              scan_asn1dertag(3)

#include<libowfat/scan.h>

       size_t scan_asn1dertag(const char *src,size_t len,unsigned long long *dest);