- The switch should now forward packets along a single path more consistently in cases where congestion is low and multiple equal-length paths exist, which should improve stability and result in fewer out-of-order packets
- Sessions should now be more tolerant of out-of-order packets, by replacing a bitmask with a variable sized heap+map structure to track recently received nonces, which should reduce the number of packets dropped due to reordering when multiple paths are used or multiple independent flows are transmitted through the same session
- In low-traffic scenarios where there are multiple peerings between a pair of nodes, Yggdrasil now prefers the most active peering instead of the least active, helping to reduce packet reordering
- The `Listen` statement, when configured as a string rather than an array, will now be parsed correctly
- The admin socket now returns `coords` as a correct array of unsigned 64-bit integers, rather than the internal representation
- Yggdrasil now has a public API with interfaces such as `yggdrasil.ConnDialer`, `yggdrasil.ConnListener` and `yggdrasil.Conn` for using Yggdrasil as a transport directly within applications
- Session gatekeeper functions, part of the API, which can be used to control whether to allow or reject incoming or outgoing sessions dynamically (compared to the previous fixed whitelist/blacklist approach)
- Support for logging to files or syslog (where supported)
- Platform defaults now include the ability to set sane defaults for multicast interfaces
### Changed
- Following a massive refactoring exercise, Yggdrasil's codebase has now been broken out into modules
- Core node functionality in the `yggdrasil` package with a public API
- This allows Yggdrasil to be integrated directly into other applications and used as a transport
- IP-specific code has now been moved out of the core `yggdrasil` package, making Yggdrasil effectively protocol-agnostic
- Multicast peer discovery functionality is now in the `multicast` package
- Admin socket functionality is now in the `admin` package and uses the Yggdrasil public API
- TUN/TAP, ICMPv6 and all IP-specific functionality is now in the `tuntap` package
-`PPROF` debug output is now sent to `stderr` instead of `stdout`
- Node IPv6 addresses on macOS are now configured as `secured`
- Upstream dependency references have been updated, which includes a number of fixes in the Water library
### Fixed
- Multicast discovery is no longer disabled if the nominated interfaces aren't available on the system yet, e.g. during boot
- Multicast interfaces are now re-evaluated more frequently so that Yggdrasil doesn't need to be restarted to use interfaces that have become available since startup
- Admin socket error cases are now handled better
- Various fixes in the TUN/TAP module, particularly surrounding Windows platform support
- Invalid keys will now cause the node to fail to start, rather than starting but silently not working as before
- Session MTUs are now always calculated correctly, in some cases they were incorrectly defaulting to 1280 before
- Multiple searches now don't take place for a single connection
- The `AllowedEncryptionPublicKeys` option has now been fixed to handle incoming connections properly and no longer blocks outgoing connections (this was broken in v0.3.4)
- Multicast TCP listeners will now be stopped correctly when the link-local address on the interface changes or disappears altogether
- On macOS, Yggdrasil will now try to wake up AWDL on start-up when `awdl0` is a configured multicast interface, to keep it awake after system sleep, and to stop waking it when no longer needed
- Added `LinkLocalTCPPort` option for controlling the port number that link-local TCP listeners will listen on by default when setting up `MulticastInterfaces` (a node restart is currently required for changes to `LinkLocalTCPPort` to take effect - it cannot be updated by reloading config during runtime)
- The `Listen` configuration statement is now an array instead of a string
- The `Listen` configuration statement should now conform to the same formatting as peers with the protocol prefix, e.g. `tcp://[::]:0`
- Session workers are now non-blocking
- Multicast interval is now fixed at every 15 seconds and network interfaces are reevaluated for eligibility on each interval (where before the interval depended upon the number of configured multicast interfaces and evaluation only took place at startup)
- Dead connections are now closed in the link handler as opposed to the switch
- Peer forwarding is now prioritised instead of randomised
### Fixed
- Admin socket `getTunTap` call now returns properly instead of claiming no interface is enabled in all cases
- Handling of `getRoutes` etc in `yggdrasilctl` is now working
- Local interface names are no longer leaked in multicast packets
- Link-local TCP connections, particularly those initiated because of multicast beacons, are now always correctly scoped for the target interface
- Yggdrasil now correctly responds to multicast interfaces going up and down during runtime
- Dynamic reconfiguration, which allows reloading the configuration file to make changes during runtime by sending a `SIGHUP` signal (note: this only works with `-useconffile` and not `-useconf` and currently reconfiguring TUN/TAP is not supported)
- Support for building Yggdrasil as an iOS or Android framework if the appropriate tools (e.g. `gomobile`/`gobind` + SDKs) are available
- Connection contexts used for TCP connections which allow more exotic socket options to be set, e.g.
- Reusing the multicast socket to allow multiple running Yggdrasil instances without having to disable multicast
- Allowing supported Macs to peer with other nearby Macs that aren't even on the same Wi-Fi network using AWDL
- Flexible logging support, which allows for logging at different levels of verbosity
### Changed
- Switch changes to improve parent selection
- Node configuration is now stored centrally, rather than having fragments/copies distributed at startup time
- Significant refactoring in various areas, including for link types (TCP, AWDL etc), generic streams and adapters
- macOS builds through CircleCI are now 64-bit only
- The admin socket is now multithreaded, greatly improving performance of the crawler and allowing concurrent lookups to take place
- The ability to hide NodeInfo defaults through either setting the `NodeInfoPrivacy` option or through setting individual `NodeInfo` attributes to `null`
### Changed
- The `armhf` build now targets ARMv6 instead of ARMv7, adding support for Raspberry Pi Zero and other older models, amongst others
### Fixed
- DHT entries are now populated using a copy in memory to fix various potential DHT bugs
- DHT traffic should now throttle back exponentially to reduce idle traffic
- Adjust how nodes are inserted into the DHT which should help to reduce some incorrect DHT traffic
- In TAP mode, the NDP target address is now correctly used when populating the peer MAC table. This fixes serious connectivity problems when in TAP mode, particularly on BSD
- In TUN mode, ICMPv6 packets are now ignored whereas they were incorrectly processed before
- The address range was moved from `fd00::/8` to `200::/7`. This range was chosen as it is marked as deprecated. The change prevents overlap with other ULA privately assigned ranges.
- UTF-16 detection conversion for configuration files, which can particularly be a problem on Windows 10 if a configuration file is generated from within PowerShell.
- Exchange version information during connection setup, to prevent connections with incompatible versions.
### Changed
- Wire format changes (backwards incompatible).
- Less maintenance traffic per peer.
- Exponential back-off for DHT maintenance traffic (less maintenance traffic for known good peers).
- Iterative DHT (added some time between v0.1.0 and here).
- Use local queue sizes for a sort of local-only backpressure routing, instead of the removed bandwidth estimates, when deciding where to send a packet.
### Removed
- UDP peering, this may be added again if/when a better implementation appears.
