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fix BER tag length check when length is between 0x80 and 0xFF #68

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fix BER tag length check when length is between 0x80 and 0xFF #68

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8 changes: 4 additions & 4 deletions ber.go
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Original file line number Diff line number Diff line change
Expand Up @@ -181,20 +181,20 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
if numberOfBytes > 4 { // int is only guaranteed to be 32bit
return nil, 0, errors.New("ber2der: BER tag length too long")
}
if offset+numberOfBytes > berLen {
return nil, 0, errors.New("ber2der: cannot move offset forward, end of ber data reached")
}
if numberOfBytes == 4 && (int)(ber[offset]) > 0x7F {
return nil, 0, errors.New("ber2der: BER tag length is negative")
}
if (int)(ber[offset]) == 0x0 {
if ber[offset] == 0x0 && (numberOfBytes == 1 || ber[offset+1] <= 0x7F) {
return nil, 0, errors.New("ber2der: BER tag length has leading zero")
}
debugprint("--> (compute length) indicator byte: %x\n", l)
debugprint("--> (compute length) length bytes: % X\n", ber[offset:offset+numberOfBytes])
for i := 0; i < numberOfBytes; i++ {
length = length*256 + (int)(ber[offset])
offset++
if offset > berLen {
return nil, 0, errors.New("ber2der: cannot move offset forward, end of ber data reached")
}
}
} else if l == 0x80 {
indefinite = true
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