/usr/share/gocode/src/github.com/miekg/dns/rawmsg.go is in golang-github-miekg-dns-dev 0.0~git20170501.0.f282f80-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | package dns
import "encoding/binary"
// rawSetRdlength sets the rdlength in the header of
// the RR. The offset 'off' must be positioned at the
// start of the header of the RR, 'end' must be the
// end of the RR.
func rawSetRdlength(msg []byte, off, end int) bool {
l := len(msg)
Loop:
for {
if off+1 > l {
return false
}
c := int(msg[off])
off++
switch c & 0xC0 {
case 0x00:
if c == 0x00 {
// End of the domainname
break Loop
}
if off+c > l {
return false
}
off += c
case 0xC0:
// pointer, next byte included, ends domainname
off++
break Loop
}
}
// The domainname has been seen, we at the start of the fixed part in the header.
// Type is 2 bytes, class is 2 bytes, ttl 4 and then 2 bytes for the length.
off += 2 + 2 + 4
if off+2 > l {
return false
}
//off+1 is the end of the header, 'end' is the end of the rr
//so 'end' - 'off+2' is the length of the rdata
rdatalen := end - (off + 2)
if rdatalen > 0xFFFF {
return false
}
binary.BigEndian.PutUint16(msg[off:], uint16(rdatalen))
return true
}
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