The `IPv4Address(_ bytes: [UInt8])` initializer in
ContainerizationExtras shifts the third octet by 16 bits instead of 8:
```swift
self.value =
(UInt32(bytes[0]) << 24)
| (UInt32(bytes[1]) << 16)
| (UInt32(bytes[2]) << 16) // should be << 8
| UInt32(bytes[3])
```
Because `bytes[2]` lands in the same bit range as `bytes[1]`, the second
octet gets corrupted by the OR, the third octet is dropped, and bits 8
through 15 are always left zero. Concretely, decoding `[192, 168, 1, 1]`
yields `192.169.0.1` instead of `192.168.1.1`, and `[18, 52, 86, 120]`
yields `18.118.0.120` instead of `18.52.86.120`.
This went unnoticed because the `bytes` computed property getter uses
the correct `>> 8` for the third octet, but there was no test exercising
the byte-array initializer, so the encode and decode paths were never
checked against each other. The sibling `IPv6Address(_ bytes:)`
initializer uses the correct descending shifts (`<< 120, << 112, ... <<
8, << 0`), which is what the IPv4 version should mirror.
The fix changes the third octet shift to 8 bits so the initializer is
the exact inverse of the `bytes` property. I also added two tests to the
initializer suite: a valid-input test that asserts both the resulting
`value` and that `init(bytes).bytes == bytes` round-trips, and an
invalid-length test. The round-trip test fails on the current code and
passes with the fix.
Verification: `swift test --filter ContainerizationExtrasTests` passes
221 tests in 26 suites (the IPv4Address suite goes from 23 to 25 tests).
The new round-trip test fails before the one-line change and passes
after.
Signed-off-by: Aditya Singh <adisin650@gmail.com>
- Bindable is generally useful, so it makes sense to move it out of the
netlink library. Removed Equatable conformance from Bindable as this
isn't generally necessary (it's only used for unit tests in netlink).
- Fix some offset checks in a couple data binding functions and improve
the unit tests.
- Simplifies processing and validation of MAC addresses for
apple/container#1005, where we need to create MAC addresses and
corresponding link local IPv6 addresses.
- Adds Codable for IPAddress and CIDR for apple/container#1006, so we
can parse and relay IP addresses regardless of address family for port
forwards.
This change adds extension to the CIDR and IPAddress types to implement
custom encode/decode functions for `Codable` conformance to use their
string representation as the output from encode and input to decode.
This would make the output from encoding this type (e.g. JSON) more
human-readable rather than using the internal integer representation.
These types can benefit from swift's automatic
synthesis as the properties already conform to Codable. This will give
some flexibility for clients using these types to not have to add
extension and implement the encoding / decoding separately.
Aditya Singh