wip v1.0.0

2025-12-08 22:23:45 +08:00
commit bece440c47
35 changed files with 4893 additions and 0 deletions
--- a/internal/vrrp/socket.go
+++ b/internal/vrrp/socket.go
@@ -0,0 +1,141 @@
+package vrrp
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"syscall"
+
+	"golang.org/x/net/ipv4"
+)
+
+const (
+	VRRPMulticastAddr = "224.0.0.18"
+)
+
+type Socket struct {
+	conn     *ipv4.RawConn
+	iface    *net.Interface
+	localIP  net.IP
+	groupIP  net.IP
+}
+
+func NewSocket(ifaceName string) (*Socket, error) {
+	iface, err := net.InterfaceByName(ifaceName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get interface %s: %w", ifaceName, err)
+	}
+
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get addresses for %s: %w", ifaceName, err)
+	}
+
+	var localIP net.IP
+	for _, addr := range addrs {
+		if ipNet, ok := addr.(*net.IPNet); ok {
+			if ipv4 := ipNet.IP.To4(); ipv4 != nil {
+				localIP = ipv4
+				break
+			}
+		}
+	}
+
+	if localIP == nil {
+		return nil, fmt.Errorf("no IPv4 address found on interface %s", ifaceName)
+	}
+
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_RAW, VRRPProtocolNumber)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create raw socket: %w", err)
+	}
+
+	if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
+		syscall.Close(fd)
+		return nil, fmt.Errorf("failed to set SO_REUSEADDR: %w", err)
+	}
+
+	file := os.NewFile(uintptr(fd), "vrrp-socket")
+	defer file.Close()
+
+	packetConn, err := net.FilePacketConn(file)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create packet connection: %w", err)
+	}
+
+	rawConn, err := ipv4.NewRawConn(packetConn)
+	if err != nil {
+		packetConn.Close()
+		return nil, fmt.Errorf("failed to create raw connection: %w", err)
+	}
+
+	groupIP := net.ParseIP(VRRPMulticastAddr).To4()
+	if groupIP == nil {
+		rawConn.Close()
+		return nil, fmt.Errorf("invalid multicast address: %s", VRRPMulticastAddr)
+	}
+
+	if err := rawConn.JoinGroup(iface, &net.IPAddr{IP: groupIP}); err != nil {
+		rawConn.Close()
+		return nil, fmt.Errorf("failed to join multicast group: %w", err)
+	}
+
+	if err := rawConn.SetControlMessage(ipv4.FlagTTL|ipv4.FlagSrc|ipv4.FlagDst|ipv4.FlagInterface, true); err != nil {
+		rawConn.Close()
+		return nil, fmt.Errorf("failed to set control message: %w", err)
+	}
+
+	return &Socket{
+		conn:    rawConn,
+		iface:   iface,
+		localIP: localIP,
+		groupIP: groupIP,
+	}, nil
+}
+
+func (s *Socket) Send(pkt *VRRPPacket) error {
+	data, err := pkt.Marshal()
+	if err != nil {
+		return fmt.Errorf("failed to marshal packet: %w", err)
+	}
+
+	header := &ipv4.Header{
+		Version:  ipv4.Version,
+		Len:      ipv4.HeaderLen,
+		TOS:      0xC0,
+		TotalLen: ipv4.HeaderLen + len(data),
+		TTL:      255,
+		Protocol: VRRPProtocolNumber,
+		Dst:      s.groupIP,
+		Src:      s.localIP,
+	}
+
+	if err := s.conn.WriteTo(header, data, nil); err != nil {
+		return fmt.Errorf("failed to send packet: %w", err)
+	}
+
+	return nil
+}
+
+func (s *Socket) Receive() (*VRRPPacket, net.IP, error) {
+	buf := make([]byte, 1500)
+
+	header, payload, _, err := s.conn.ReadFrom(buf)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to receive packet: %w", err)
+	}
+
+	pkt, err := Unmarshal(payload)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to unmarshal packet: %w", err)
+	}
+
+	return pkt, header.Src, nil
+}
+
+func (s *Socket) Close() error {
+	if err := s.conn.LeaveGroup(s.iface, &net.IPAddr{IP: s.groupIP}); err != nil {
+		return err
+	}
+	return s.conn.Close()
+}