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* POST /control/dhcp/find_active_dhcp: add dhcpv6 server info

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This commit is contained in:
Simon Zolin
2020-08-13 18:45:27 +03:00
parent 23752377b7
commit e7bef3a448
5 changed files with 225 additions and 59 deletions
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104
dhcpd/check_other_dhcp.go
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@@ -13,12 +13,14 @@ import (
"github.com/AdguardTeam/golibs/log"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv4/nclient4"
"github.com/insomniacslk/dhcp/dhcpv6"
"github.com/insomniacslk/dhcp/dhcpv6/nclient6"
"github.com/insomniacslk/dhcp/iana"
)
// CheckIfOtherDHCPServersPresent sends a DHCP request to the specified network interface,
// CheckIfOtherDHCPServersPresentV4 sends a DHCP request to the specified network interface,
// and waits for a response for a period defined by defaultDiscoverTime
func CheckIfOtherDHCPServersPresent(ifaceName string) (bool, error) {
func CheckIfOtherDHCPServersPresentV4(ifaceName string) (bool, error) {
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return false, wrapErrPrint(err, "Couldn't find interface by name %s", ifaceName)
@@ -66,12 +68,12 @@ func CheckIfOtherDHCPServersPresent(ifaceName string) (bool, error) {
// bind to 0.0.0.0:68
log.Tracef("Listening to udp4 %+v", udpAddr)
c, err := nclient4.NewRawUDPConn(ifaceName, 68)
if c != nil {
defer c.Close()
}
if err != nil {
return false, wrapErrPrint(err, "Couldn't listen on :68")
}
if c != nil {
defer c.Close()
}
// send to 255.255.255.255:67
_, err = c.WriteTo(req.ToBytes(), dstAddr)
@@ -119,3 +121,95 @@ func CheckIfOtherDHCPServersPresent(ifaceName string) (bool, error) {
return true, nil
}
}
// CheckIfOtherDHCPServersPresentV6 sends a DHCP request to the specified network interface,
// and waits for a response for a period defined by defaultDiscoverTime
func CheckIfOtherDHCPServersPresentV6(ifaceName string) (bool, error) {
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return false, fmt.Errorf("DHCPv6: net.InterfaceByName: %s: %s", ifaceName, err)
}
ifaceIPNet := getIfaceIPv6(*iface)
if len(ifaceIPNet) == 0 {
return false, fmt.Errorf("DHCPv6: couldn't find IPv6 address of interface %s %+v", ifaceName, iface)
}
srcIP := ifaceIPNet[0]
src := net.JoinHostPort(srcIP.String(), "546")
dst := "[ff02::1:2]:547"
req, err := dhcpv6.NewSolicit(iface.HardwareAddr)
if err != nil {
return false, fmt.Errorf("DHCPv6: dhcpv6.NewSolicit: %s", err)
}
udpAddr, err := net.ResolveUDPAddr("udp6", src)
if err != nil {
return false, wrapErrPrint(err, "DHCPv6: Couldn't resolve UDP address %s", src)
}
if !udpAddr.IP.To16().Equal(srcIP) {
return false, wrapErrPrint(err, "DHCPv6: Resolved UDP address is not %s", src)
}
dstAddr, err := net.ResolveUDPAddr("udp6", dst)
if err != nil {
return false, fmt.Errorf("DHCPv6: Couldn't resolve UDP address %s: %s", dst, err)
}
log.Debug("DHCPv6: Listening to udp6 %+v", udpAddr)
c, err := nclient6.NewIPv6UDPConn(ifaceName, dhcpv6.DefaultClientPort)
if err != nil {
return false, fmt.Errorf("DHCPv6: Couldn't listen on :546: %s", err)
}
if c != nil {
defer c.Close()
}
_, err = c.WriteTo(req.ToBytes(), dstAddr)
if err != nil {
return false, fmt.Errorf("DHCPv6: Couldn't send a packet to %s: %s", dst, err)
}
for {
log.Debug("DHCPv6: Waiting %v for an answer", defaultDiscoverTime)
b := make([]byte, 4096)
_ = c.SetReadDeadline(time.Now().Add(defaultDiscoverTime))
n, _, err := c.ReadFrom(b)
if isTimeout(err) {
log.Debug("DHCPv6: didn't receive DHCP response")
return false, nil
}
if err != nil {
return false, wrapErrPrint(err, "Couldn't receive packet")
}
log.Debug("DHCPv6: Received packet (%v bytes)", n)
resp, err := dhcpv6.FromBytes(b[:n])
if err != nil {
log.Debug("DHCPv6: dhcpv6.FromBytes: %s", err)
continue
}
log.Debug("DHCPv6: received message from server: %s", resp.Summary())
cid := req.Options.ClientID()
msg, err := resp.GetInnerMessage()
if err != nil {
log.Debug("DHCPv6: resp.GetInnerMessage: %s", err)
continue
}
rcid := msg.Options.ClientID()
if resp.Type() == dhcpv6.MessageTypeAdvertise &&
msg.TransactionID == req.TransactionID &&
rcid != nil &&
cid.Equal(*rcid) {
log.Debug("DHCPv6: The packet is from an active DHCP server")
return true, nil
}
log.Debug("DHCPv6: received message from server doesn't match our request")
}
}