Add ping client

ping/socket_unix.go

@@ -0,0 +1,86 @@
+//go:build unix
+
+package ping
+
+import (
+	"net"
+	"net/netip"
+	"os"
+	"runtime"
+	"syscall"
+
+	"github.com/sagernet/sing/common/control"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	"golang.org/x/sys/unix"
+)
+
+func connect(privileged bool, controlFunc control.Func, destination netip.Addr) (net.Conn, error) {
+	var (
+		network string
+		fd      int
+		err     error
+	)
+	if destination.Is4() {
+		network = "ip4:icmp"
+		if !privileged {
+			fd, err = unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_ICMP)
+		} else {
+			fd, err = unix.Socket(unix.AF_INET, unix.SOCK_RAW, unix.IPPROTO_ICMP)
+		}
+	} else {
+		network = "ip6:icmp"
+		if !privileged {
+			fd, err = unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_ICMPV6)
+		} else {
+			fd, err = unix.Socket(unix.AF_INET6, unix.SOCK_RAW, unix.IPPROTO_ICMPV6)
+		}
+	}
+	if err != nil {
+		return nil, E.Cause(err, "socket()")
+	}
+	file := os.NewFile(uintptr(fd), "datagram-oriented icmp")
+	defer file.Close()
+	err = unix.Connect(fd, M.AddrPortToSockaddr(netip.AddrPortFrom(destination, 0)))
+	if err != nil {
+		return nil, E.Cause(err, "connect()")
+	}
+
+	if destination.Is4() && runtime.GOOS == "linux" {
+		//err = unix.SetsockoptInt(fd, unix.IPPROTO_IP, unix.IP_RECVTOS, 1)
+		//if err != nil {
+		//	return nil, err
+		//}
+		err = unix.SetsockoptInt(fd, unix.IPPROTO_IP, unix.IP_RECVTTL, 1)
+		if err != nil {
+			return nil, E.Cause(err, "setsockopt()")
+		}
+	}
+	if destination.Is6() {
+		err = unix.SetsockoptInt(fd, unix.IPPROTO_IPV6, unix.IPV6_RECVHOPLIMIT, 1)
+		if err != nil {
+			return nil, E.Cause(err, "setsockopt()")
+		}
+		err = unix.SetsockoptInt(fd, unix.IPPROTO_IPV6, unix.IPV6_RECVTCLASS, 1)
+		if err != nil {
+			return nil, E.Cause(err, "setsockopt()")
+		}
+	}
+
+	conn, err := net.FileConn(file)
+	if err != nil {
+		return nil, err
+	}
+	if controlFunc != nil {
+		var syscallConn syscall.RawConn
+		syscallConn, err = conn.(syscall.Conn).SyscallConn()
+		if err != nil {
+			return nil, err
+		}
+		err = controlFunc(network, destination.String(), syscallConn)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return conn, nil
+}