1 files changed, 109 insertions, 0 deletions
diff --git a/dhcpv4/bsdp_client.go b/dhcpv4/bsdp_client.go
new file mode 100644
index 0000000..5c4dc00
--- /dev/null
+++ b/dhcpv4/bsdp_client.go
@@ -0,0 +1,109 @@
+// +build darwin
+
+package dhcpv4
+
+import (
+	"fmt"
+	"net"
+	"syscall"
+)
+
+// BSDPExchange runs a full BSDP exchange (Inform[list], Ack, Inform[select],
+// Ack). Returns a list of DHCPv4 structures representing the exchange.
+func (c *Client) BSDPExchange(ifname string, d *DHCPv4) ([]DHCPv4, error) {
+	conversation := make([]DHCPv4, 1)
+	var err error
+
+	// INFORM[LIST]
+	if d == nil {
+		d, err = NewInformListForInterface(ifname, ClientPort)
+	}
+	conversation[0] = *d
+
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
+	if err != nil {
+		return conversation, err
+	}
+	err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
+	if err != nil {
+		return conversation, err
+	}
+	err = syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_HDRINCL, 1)
+	if err != nil {
+		return conversation, err
+	}
+	err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)
+	if err != nil {
+		return conversation, err
+	}
+	err = BindToInterface(fd, ifname)
+	if err != nil {
+		return conversation, err
+	}
+
+	daddr := syscall.SockaddrInet4{Port: ClientPort, Addr: [4]byte{255, 255, 255, 255}}
+	packet, err := makeRawBroadcastPacket(d.ToBytes())
+	if err != nil {
+		return conversation, err
+	}
+	err = syscall.Sendto(fd, packet, 0, &daddr)
+	if err != nil {
+		return conversation, err
+	}
+
+	// ACK 1
+	conn, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4(0, 0, 0, 0), Port: ClientPort})
+	if err != nil {
+		return conversation, err
+	}
+	defer conn.Close()
+
+	buf := make([]byte, maxUDPReceivedPacketSize)
+	oobdata := []byte{} // ignoring oob data
+	n, _, _, _, err := conn.ReadMsgUDP(buf, oobdata)
+	ack1, err := FromBytes(buf[:n])
+	if err != nil {
+		return conversation, err
+	}
+	// TODO match the packet content
+	// TODO check that the peer address matches the declared server IP and port
+	conversation = append(conversation, *ack1)
+
+	// Parse boot images sent back by server
+	bootImages, err := ParseBootImageListFromAck(*ack1)
+	fmt.Println(bootImages)
+	if err != nil {
+		return conversation, err
+	}
+	if len(bootImages) == 0 {
+		return conversation, fmt.Errorf("Got no BootImages from server")
+	}
+
+	// INFORM[SELECT]
+	request, err := InformSelectForAck(*ack1, ClientPort, bootImages[0])
+	if err != nil {
+		return conversation, err
+	}
+	conversation = append(conversation, *request)
+	packet, err = makeRawBroadcastPacket(request.ToBytes())
+	if err != nil {
+		return conversation, err
+	}
+	err = syscall.Sendto(fd, packet, 0, &daddr)
+	if err != nil {
+		return conversation, err
+	}
+
+	// ACK 2
+	buf = make([]byte, maxUDPReceivedPacketSize)
+	n, _, _, _, err = conn.ReadMsgUDP(buf, oobdata)
+	acknowledge, err := FromBytes(buf[:n])
+	if err != nil {
+		return conversation, err
+	}
+	// TODO match the packet content
+	// TODO check that the peer address matches the declared server IP and port
+	conversation = append(conversation, *acknowledge)
+
+	return conversation, nil
+}