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package bsdp
import (
"errors"
"fmt"
"net"
"github.com/insomniacslk/dhcp/dhcpv4"
)
// Client represents a BSDP client that can perform BSDP exchanges via the
// broadcast address.
type Client dhcpv4.Client
// NewClient constructs a new client with default read and write timeouts from
// dhcpv4.Client.
func NewClient() *Client {
c := dhcpv4.NewClient()
return &Client{
ReadTimeout: c.ReadTimeout,
WriteTimeout: c.WriteTimeout,
}
}
func castVendorOpt(ack *dhcpv4.DHCPv4) {
opts := ack.Options()
for i := 0; i < len(opts); i++ {
if opts[i].Code() == dhcpv4.OptionVendorSpecificInformation {
vendorOpt, err := ParseOptVendorSpecificInformation(opts[i].ToBytes())
// Oh well, we tried
if err != nil {
return
}
opts[i] = vendorOpt
}
}
}
// Exchange runs a full BSDP exchange (Inform[list], Ack, Inform[select],
// Ack). Returns a list of DHCPv4 structures representing the exchange.
func (c *Client) Exchange(ifname string, informList *dhcpv4.DHCPv4) ([]dhcpv4.DHCPv4, error) {
conversation := make([]dhcpv4.DHCPv4, 1)
var err error
// Get our file descriptor for the broadcast socket.
sendFd, err := dhcpv4.MakeBroadcastSocket(ifname)
if err != nil {
return conversation, err
}
recvFd, err := dhcpv4.MakeListeningSocket(ifname)
if err != nil {
return conversation, err
}
iface, err := net.InterfaceByName(ifname)
if err != nil {
return conversation, err
}
// Get currently configured IP.
addrs, err := iface.Addrs()
if err != nil {
return conversation, err
}
localIPs, err := dhcpv4.GetExternalIPv4Addrs(addrs)
if err != nil {
return conversation, fmt.Errorf("could not get local IPv4 addr for %s: %v", iface.Name, err)
}
// INFORM[LIST]
if informList == nil {
informList, err = NewInformList(iface.HardwareAddr, localIPs[0], dhcpv4.ClientPort)
if err != nil {
return conversation, err
}
}
conversation[0] = *informList
// ACK[LIST]
ackForList, err := dhcpv4.BroadcastSendReceive(sendFd, recvFd, informList, c.ReadTimeout, c.WriteTimeout, dhcpv4.MessageTypeAck)
if err != nil {
return conversation, err
}
// Rewrite vendor-specific option for pretty printing.
castVendorOpt(ackForList)
conversation = append(conversation, *ackForList)
// Parse boot images sent back by server
bootImages, err := ParseBootImageListFromAck(*ackForList)
if err != nil {
return conversation, err
}
if len(bootImages) == 0 {
return conversation, errors.New("got no BootImages from server")
}
// INFORM[SELECT]
informSelect, err := InformSelectForAck(*ackForList, dhcpv4.ClientPort, bootImages[0])
if err != nil {
return conversation, err
}
conversation = append(conversation, *informSelect)
// ACK[SELECT]
ackForSelect, err := dhcpv4.BroadcastSendReceive(sendFd, recvFd, informSelect, c.ReadTimeout, c.WriteTimeout, dhcpv4.MessageTypeAck)
castVendorOpt(ackForSelect)
if err != nil {
return conversation, err
}
return append(conversation, *ackForSelect), nil
}
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