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Avoid using a goto loop in unpackDataOpt (#1505)

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We definitely shouldn't be using goto for a simple loop.

This is technically a behaviour change when off == len(msg), but we're
always called with off < len(msg) so this is unobservable.
This commit is contained in:
Tom Thorogood 2023-11-06 16:56:49 +10:30 committed by GitHub
parent 1c418a37a5
commit 3996b17d19
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 17 additions and 22 deletions
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39
msg_helpers.go
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@ -406,29 +406,24 @@ func packStringTxt(s []string, msg []byte, off int) (int, error) {
func unpackDataOpt(msg []byte, off int) ([]EDNS0, int, error) {
var edns []EDNS0
Option:
var code uint16
if off+4 > len(msg) {
return nil, len(msg), &Error{err: "overflow unpacking opt"}
for off < len(msg) {
if off+4 > len(msg) {
return nil, len(msg), &Error{err: "overflow unpacking opt"}
}
code := binary.BigEndian.Uint16(msg[off:])
off += 2
optlen := binary.BigEndian.Uint16(msg[off:])
off += 2
if off+int(optlen) > len(msg) {
return nil, len(msg), &Error{err: "overflow unpacking opt"}
}
opt := makeDataOpt(code)
if err := opt.unpack(msg[off : off+int(optlen)]); err != nil {
return nil, len(msg), err
}
edns = append(edns, opt)
off += int(optlen)
}
code = binary.BigEndian.Uint16(msg[off:])
off += 2
optlen := binary.BigEndian.Uint16(msg[off:])
off += 2
if off+int(optlen) > len(msg) {
return nil, len(msg), &Error{err: "overflow unpacking opt"}
}
e := makeDataOpt(code)
if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
return nil, len(msg), err
}
edns = append(edns, e)
off += int(optlen)
if off < len(msg) {
goto Option
}
return edns, off, nil
}