Make the net package address-family aware instead of IPv4-only: DialTCP,
listenTCP and DialUDP now choose AF_INET or AF_INET6 from the target address
(socketFamily), the "only ipv4 supported" guard is replaced by a 4-or-16 byte
check, and "tcp6"/"udp6" network names are accepted.
In the host netdev, sockaddrFromParts builds a SockaddrInet6 for IPv6 addresses
(SockaddrInet4 otherwise), Accept decodes both families, GetHostByName and the
/etc/hosts lookup accept IPv6, and the stub resolver now queries AAAA after A.
Name resolution still prefers IPv4, so the "4"/"6" suffix is advisory for host
names; this is documented on Dial/Listen. Link-local IPv6 zones are not mapped
to a scope id.
Verified on linux/amd64 with tinygo: IPv6 loopback Listen/Accept/Dial over
[::1], AAAA fallback for an IPv6-only host name, and IPv4 behaviour unchanged.
On the native linux target the net package defaulted to a NOP netdev that
returns "Netdev not set" for every operation, so net.Dial/Listen, DNS and
anything built on them (net/http, tls) failed at runtime.
Native linux does not override the syscall package, and the TinyGo compiler
lowers syscall.Syscall/RawSyscall into real system calls, so the standard
library socket functions work directly (musl's omitted network module is not
needed). Register a default netdev implementing the netdever interface on top
of syscall.Socket/Connect/Bind/Listen/Accept/Send/Recv/SetSockOpt, plus a
small UDP DNS resolver (/etc/hosts, /etc/resolv.conf) for GetHostByName. Also
restore the net.DNSError type used by resolution errors.
Blocking sockets under the threads scheduler; IPv4 only. This avoids the
internal/poll netpoller dependency that blocked the upstream-net approach.
Refs tinygo-org/net#28
Moses Narrow