OXIESEC PANEL

Name	Size	Modified	Perms
📁 ..	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 addrselect.go	9.69 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 addrselect_test.go	8.5 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_aix.go	582 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_android.go	272 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_bsd.go	343 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_darwin.go	298 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_linux.go	642 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_netbsd.go	276 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_openbsd.go	276 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_resnew.go	580 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_resold.go	579 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_socknew.go	753 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_sockold.go	842 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_solaris.go	343 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_stub.go	1.33 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix.go	11.35 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_cgo.go	2.24 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_cgo_darwin.go	461 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_cgo_res.go	911 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_cgo_resn.go	998 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_syscall.go	2.99 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 cgo_unix_test.go	1.44 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 conf.go	15.63 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 conf_test.go	12.28 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 conn_test.go	1.82 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dial.go	25.68 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dial_test.go	30.14 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dial_unix_test.go	2.77 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsclient.go	5.65 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsclient_test.go	1.51 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsclient_unix.go	24.26 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsclient_unix_test.go	69.13 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsconfig.go	1.73 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsconfig_unix.go	4.16 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsconfig_unix_test.go	7.07 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsconfig_windows.go	1.6 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 dnsname_test.go	1.96 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_plan9.go	224 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_plan9_test.go	437 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_posix.go	543 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_posix_test.go	981 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_test.go	20.32 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_unix.go	382 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_unix_test.go	723 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_windows.go	355 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 error_windows_test.go	757 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 example_test.go	8.45 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 external_test.go	4.05 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_fake.go	3.79 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_js.go	627 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_plan9.go	3.56 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_posix.go	4.29 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_unix.go	5.43 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_wasip1.go	496 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 fd_windows.go	6.14 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file.go	1.69 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_plan9.go	2.72 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_stub.go	481 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_test.go	6.43 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_unix.go	2.5 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_unix_test.go	2.07 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_wasip1.go	2.2 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_wasip1_test.go	3.76 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 file_windows.go	521 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 hook.go	894 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 hook_plan9.go	211 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 hook_unix.go	658 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 hook_windows.go	720 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 hosts.go	3.48 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 hosts_test.go	5.6 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 http	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 interface.go	7.26 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_aix.go	4.46 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_bsd.go	2.82 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_bsd_test.go	1.44 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_bsdvar.go	718 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_darwin.go	1.29 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_freebsd.go	1.29 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_linux.go	6.96 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_linux_test.go	3.65 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_plan9.go	4.71 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_solaris.go	2.13 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_stub.go	814 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_test.go	9.76 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_unix_test.go	4.85 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 interface_windows.go	5.43 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 internal	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 ip.go	13.88 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 ip_test.go	25.6 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 iprawsock.go	7.11 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 iprawsock_plan9.go	874 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 iprawsock_posix.go	3.89 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 iprawsock_test.go	5.98 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 ipsock.go	9.05 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 ipsock_plan9.go	7.48 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 ipsock_plan9_test.go	645 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 ipsock_posix.go	7.86 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 ipsock_test.go	6.81 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 listen_test.go	20.5 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup.go	29.04 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup_plan9.go	9.94 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup_test.go	40.62 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup_unix.go	3.35 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup_windows.go	13.8 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 lookup_windows_test.go	8.93 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mac.go	1.88 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mac_test.go	3.26 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 mail	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 main_cloexec_test.go	693 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_conf_test.go	1.39 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_noconf_test.go	467 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_plan9_test.go	392 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_posix_test.go	1.37 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_test.go	7.53 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_unix_test.go	1.19 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_wasm_test.go	284 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 main_windows_test.go	1 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mockserver_test.go	10.77 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mptcpsock_linux.go	3.96 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mptcpsock_linux_test.go	4.06 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 mptcpsock_stub.go	542 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 net.go	24.56 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 net_fake.go	26.36 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 net_fake_test.go	2.79 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 net_test.go	14 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 net_windows_test.go	16.28 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 netcgo_off.go	222 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 netcgo_on.go	220 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 netgo_netcgo.go	453 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 netgo_off.go	220 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 netgo_on.go	218 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📁 netip	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 nss.go	5.48 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 nss_test.go	3.4 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 packetconn_test.go	3.02 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 parse.go	6.04 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 parse_test.go	1.55 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 pipe.go	5.43 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 pipe_test.go	1.2 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 platform_test.go	4.33 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 port.go	1.46 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 port_test.go	1.34 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 port_unix.go	1.24 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 protoconn_test.go	7.44 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 rawconn.go	2.7 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 rawconn_stub_test.go	631 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 rawconn_test.go	4.33 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 rawconn_unix_test.go	2.96 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 rawconn_windows_test.go	3.12 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 resolverdialfunc_test.go	8.25 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 rlimit_js.go	346 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 rlimit_unix.go	1.1 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 rpc	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 sendfile_linux.go	1.12 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sendfile_linux_test.go	1.93 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sendfile_stub.go	344 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sendfile_test.go	8.25 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sendfile_unix_alt.go	2.04 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sendfile_windows.go	1.02 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 server_test.go	11.67 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 smtp	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 sock_bsd.go	918 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_cloexec.go	1.38 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_linux.go	993 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_linux_test.go	575 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_plan9.go	262 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_posix.go	6.29 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_stub.go	390 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sock_windows.go	802 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockaddr_posix.go	1.45 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_aix.go	1.43 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_bsd.go	2.21 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_fake.go	955 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_linux.go	1.25 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_plan9.go	406 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_posix.go	2.13 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_solaris.go	1.25 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockopt_windows.go	1.51 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockoptip_bsdvar.go	867 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockoptip_linux.go	735 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockoptip_posix.go	1.38 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockoptip_stub.go	769 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 sockoptip_windows.go	786 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 splice_linux.go	1.69 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 splice_stub.go	376 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 splice_test.go	13.48 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 sys_cloexec.go	962 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsock.go	11.75 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsock_plan9.go	2.18 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsock_posix.go	6.16 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsock_test.go	17.68 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsock_unix_test.go	2.34 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_darwin.go	770 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_dragonfly.go	698 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_openbsd.go	365 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_plan9.go	525 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_posix.go	442 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_solaris.go	1.15 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_stub.go	399 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_unix.go	722 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 tcpsockopt_windows.go	741 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📁 testdata	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📁 textproto	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 timeout_test.go	29.11 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 udpsock.go	11.83 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 udpsock_plan9.go	4.64 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 udpsock_plan9_test.go	1.31 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 udpsock_posix.go	7.53 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 udpsock_test.go	17.24 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock.go	10.12 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_linux_test.go	2.29 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_plan9.go	1.24 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_posix.go	6.64 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_readmsg_cloexec.go	654 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_readmsg_cmsg_cloexec.go	332 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_readmsg_other.go	275 bytes	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_readmsg_test.go	2.51 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_test.go	10.64 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 unixsock_windows_test.go	2.03 KB	02/02/2024 06:09:55 PM	rw-r--r--
📁 url	-	02/02/2024 06:09:55 PM	rwxr-xr-x
📄 write_unix_test.go	1.61 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 writev_test.go	5.03 KB	02/02/2024 06:09:55 PM	rw-r--r--
📄 writev_unix.go	666 bytes	02/02/2024 06:09:55 PM	rw-r--r--

Editing: udpsock_plan9.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package net

import (
	"context"
	"errors"
	"net/netip"
	"os"
	"syscall"
)

func (c *UDPConn) readFrom(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
	buf := make([]byte, udpHeaderSize+len(b))
	m, err := c.fd.Read(buf)
	if err != nil {
		return 0, nil, err
	}
	if m < udpHeaderSize {
		return 0, nil, errors.New("short read reading UDP header")
	}
	buf = buf[:m]

h, buf := unmarshalUDPHeader(buf)
	n := copy(b, buf)
	*addr = UDPAddr{IP: h.raddr, Port: int(h.rport)}
	return n, addr, nil
}

func (c *UDPConn) readFromAddrPort(b []byte) (int, netip.AddrPort, error) {
	// TODO: optimize. The equivalent code on posix is alloc-free.
	buf := make([]byte, udpHeaderSize+len(b))
	m, err := c.fd.Read(buf)
	if err != nil {
		return 0, netip.AddrPort{}, err
	}
	if m < udpHeaderSize {
		return 0, netip.AddrPort{}, errors.New("short read reading UDP header")
	}
	buf = buf[:m]

h, buf := unmarshalUDPHeader(buf)
	n := copy(b, buf)
	ip, _ := netip.AddrFromSlice(h.raddr)
	addr := netip.AddrPortFrom(ip, h.rport)
	return n, addr, nil
}

func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
	return 0, 0, 0, netip.AddrPort{}, syscall.EPLAN9
}

func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
	if addr == nil {
		return 0, errMissingAddress
	}
	h := new(udpHeader)
	h.raddr = addr.IP.To16()
	h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
	h.ifcaddr = IPv6zero // ignored (receive only)
	h.rport = uint16(addr.Port)
	h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)

buf := make([]byte, udpHeaderSize+len(b))
	i := copy(buf, h.Bytes())
	copy(buf[i:], b)
	if _, err := c.fd.Write(buf); err != nil {
		return 0, err
	}
	return len(b), nil
}

func (c *UDPConn) writeToAddrPort(b []byte, addr netip.AddrPort) (int, error) {
	return c.writeTo(b, UDPAddrFromAddrPort(addr)) // TODO: optimize instead of allocating
}

func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
	return 0, 0, syscall.EPLAN9
}

func (c *UDPConn) writeMsgAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn int, err error) {
	return 0, 0, syscall.EPLAN9
}

func (sd *sysDialer) dialUDP(ctx context.Context, laddr, raddr *UDPAddr) (*UDPConn, error) {
	fd, err := dialPlan9(ctx, sd.network, laddr, raddr)
	if err != nil {
		return nil, err
	}
	return newUDPConn(fd), nil
}

const udpHeaderSize = 16*3 + 2*2

type udpHeader struct {
	raddr, laddr, ifcaddr IP
	rport, lport          uint16
}

func (h *udpHeader) Bytes() []byte {
	b := make([]byte, udpHeaderSize)
	i := 0
	i += copy(b[i:i+16], h.raddr)
	i += copy(b[i:i+16], h.laddr)
	i += copy(b[i:i+16], h.ifcaddr)
	b[i], b[i+1], i = byte(h.rport>>8), byte(h.rport), i+2
	b[i], b[i+1], i = byte(h.lport>>8), byte(h.lport), i+2
	return b
}

func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
	h := new(udpHeader)
	h.raddr, b = IP(b[:16]), b[16:]
	h.laddr, b = IP(b[:16]), b[16:]
	h.ifcaddr, b = IP(b[:16]), b[16:]
	h.rport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
	h.lport, b = uint16(b[0])<<8|uint16(b[1]), b[2:]
	return h, b
}

func (sl *sysListener) listenUDP(ctx context.Context, laddr *UDPAddr) (*UDPConn, error) {
	l, err := listenPlan9(ctx, sl.network, laddr)
	if err != nil {
		return nil, err
	}
	_, err = l.ctl.WriteString("headers")
	if err != nil {
		return nil, err
	}
	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
	if err != nil {
		return nil, err
	}
	fd, err := l.netFD()
	return newUDPConn(fd), err
}

func (sl *sysListener) listenMulticastUDP(ctx context.Context, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
	// Plan 9 does not like announce command with a multicast address,
	// so do not specify an IP address when listening.
	l, err := listenPlan9(ctx, sl.network, &UDPAddr{IP: nil, Port: gaddr.Port, Zone: gaddr.Zone})
	if err != nil {
		return nil, err
	}
	_, err = l.ctl.WriteString("headers")
	if err != nil {
		return nil, err
	}
	var addrs []Addr
	if ifi != nil {
		addrs, err = ifi.Addrs()
		if err != nil {
			return nil, err
		}
	} else {
		addrs, err = InterfaceAddrs()
		if err != nil {
			return nil, err
		}
	}

have4 := gaddr.IP.To4() != nil
	for _, addr := range addrs {
		if ipnet, ok := addr.(*IPNet); ok && (ipnet.IP.To4() != nil) == have4 {
			_, err = l.ctl.WriteString("addmulti " + ipnet.IP.String() + " " + gaddr.IP.String())
			if err != nil {
				return nil, &OpError{Op: "addmulti", Net: "", Source: nil, Addr: ipnet, Err: err}
			}
		}
	}
	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
	if err != nil {
		return nil, err
	}
	fd, err := l.netFD()
	if err != nil {
		return nil, err
	}
	return newUDPConn(fd), nil
}