Created examples directory and adjusted README

7 files changed, 182 insertions, 0 deletions

diff --git a/examples/client6/README.md b/examples/client6/README.md
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+# DHCPv6 client
+
+A minimal DHCPv6 client can be implemented in a few lines of code, by using the default
+client parameters. The example in [main.go](./main.go) lets you specify the
+interface to send packets through, and defaults to `eth0`.
diff --git a/examples/client6/main.go b/examples/client6/main.go
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+package main
+
+import (
+	"flag"
+	"log"
+
+	"github.com/insomniacslk/dhcp/dhcpv6/client6"
+)
+
+var (
+	iface = flag.String("i", "eth0", "Interface to configure via DHCPv6")
+)
+
+func main() {
+	flag.Parse()
+	log.Printf("Starting DHCPv6 client on interface %s", *iface)
+
+	// NewClient sets up a new DHCPv6 client with default values
+	// for read and write timeouts, for destination address and listening
+	// address
+	client := client6.NewClient()
+
+	// Exchange runs a Solicit-Advertise-Request-Reply transaction on the
+	// specified network interface, and returns a list of DHCPv6 packets
+	// (a "conversation") and an error if any. Notice that Exchange may
+	// return a non-empty packet list even if there is an error. This is
+	// intended, because the transaction may fail at any point, and we
+	// still want to know what packets were exchanged until then.
+	// A default Solicit packet will be used during the "conversation",
+	// which can be manipulated by using modifiers.
+	conversation, err := client.Exchange(*iface)
+
+	// Summary() prints a verbose representation of the exchanged packets.
+	for _, packet := range conversation {
+		log.Print(packet.Summary())
+	}
+	// error handling is done *after* printing, so we still print the
+	// exchanged packets if any, as explained above.
+	if err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/examples/packetcrafting6/README.md b/examples/packetcrafting6/README.md
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+# DHCPv6 packet crafting
+
+It is easy to parse, create and manipulate DHCPv6 packets. The `DHCPv6`
+interface is the central way to move packets around. Two concrete
+implementations, `DHCPv6Message` and `DHCPv6Relay` take care of the
+details. The example in [main.go](./main.go) shows how to craft a DHCP6
+Solicit message with a custom DUID_LLT, encapsulate it in a Relay message,
+and print its details.
+
+
+The output (slightly modified for readability) is
+```
+$ go run main.go
+2018/11/08 13:56:31 DHCPv6Relay
+  messageType=RELAY-FORW
+  hopcount=0
+  linkaddr=2001:db8::1
+  peeraddr=2001:db8::2
+  options=[OptRelayMsg{relaymsg=DHCPv6Message(messageType=SOLICIT transactionID=0x9e0242, 4 options)}]
+
+2018/11/08 13:56:31 [12 0 32 1 13 184 0 0 0 0 0 0 0 0 0 0 0 1 32 1 13 184
+                     0 0 0 0 0 0 0 0 0 0 0 2 0 9 0 52 1 158 2 66 0 1 0 14
+                     0 1 0 1 35 118 253 15 0 250 206 176 12 0 0 6 0 4 0 23
+                     0 24 0 8 0 2 0 0 0 3 0 12 250 206 176 12 0 0 14 16 0
+                     0 21 24]
+```
diff --git a/examples/packetcrafting6/main.go b/examples/packetcrafting6/main.go
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+++ b/examples/packetcrafting6/main.go
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+package main
+
+import (
+	"log"
+	"net"
+
+	"github.com/insomniacslk/dhcp/dhcpv6"
+	"github.com/insomniacslk/dhcp/iana"
+)
+
+func main() {
+	// In this example we create and manipulate a DHCPv6 solicit packet
+	// and encapsulate it in a relay packet. To to this, we use
+	// `dhcpv6.DHCPv6Message` and `dhcpv6.DHCPv6Relay`, two structures
+	// that implement the `dhcpv6.DHCPv6` interface.
+	// Then print the wire-format representation of the packet.
+
+	// Create the DHCPv6 Solicit first, using the interface "eth0"
+	// to get the MAC address
+	msg, err := dhcpv6.NewSolicitForInterface("eth0")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// In this example I want to redact the MAC address of my
+	// network interface, so instead of replacing it manually,
+	// I will show how to use modifiers for the purpose.
+	// A Modifier is simply a function that can be applied on
+	// a DHCPv6 object to manipulate it. Here we use it to
+	// replace the MAC address with a dummy one.
+	// Modifiers can be passed to many functions, for example
+	// to constructors, `Exchange()`, `Solicit()`, etc. Check
+	// the source code to know where to use them.
+	// Existing modifiers are implemented in dhcpv6/modifiers.go .
+	mac, err := net.ParseMAC("00:fa:ce:b0:0c:00")
+	if err != nil {
+		log.Fatal(err)
+	}
+	duid := dhcpv6.Duid{
+		Type:          dhcpv6.DUID_LLT,
+		HwType:        iana.HWTypeEthernet,
+		Time:          dhcpv6.GetTime(),
+		LinkLayerAddr: mac,
+	}
+	// As suggested above, an alternative is to call
+	// dhcpv6.NewSolicitForInterface("eth0", dhcpv6.WithCLientID(duid))
+	msg = dhcpv6.WithClientID(duid)(msg)
+
+	// Now encapsulate the message in a DHCPv6 relay.
+	// As per RFC3315, the link-address and peer-address have
+	// to be set by the relay agent. We use dummy values here.
+	linkAddr := net.ParseIP("2001:0db8::1")
+	peerAddr := net.ParseIP("2001:0db8::2")
+	relay, err := dhcpv6.EncapsulateRelay(msg, dhcpv6.MessageTypeRelayForward, linkAddr, peerAddr)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Print a verbose representation of the relay packet, that will also
+	// show a short representation of the inner Solicit message.
+	// To print a detailed summary of the inner packet, extract it
+	// first from the relay using `relay.GetInnerMessage()`.
+	log.Print(relay.Summary())
+
+	// And finally, print the bytes that would be sent on the wire
+	log.Print(relay.ToBytes())
+
+	// Note: there are many more functions in the library, check them
+	// out in the source code. For example, if you want to decode a
+	// byte stream into a DHCPv6 message or relay, you can use
+	// `dhcpv6.FromBytes`.
+}
diff --git a/examples/server6/README.md b/examples/server6/README.md
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+# DHCPv6 server
+
+A DHCPv6 server requires the user to implement a request handler. Basically the
+user has to provide the logic to answer to each packet. The library offers a few
+facilities to forge response packets, e.g. `NewAdvertiseFromSolicit`,
+`NewReplyFromDHCPv6Message` and so on. Look at the source code to see what's
+available.
+
+An example server that will print (but not reply to) the client's request is
+shown in [main.go](./main.go)
diff --git a/examples/server6/main.go b/examples/server6/main.go
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+++ b/examples/server6/main.go
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+package main
+
+import (
+	"log"
+	"net"
+
+	"github.com/insomniacslk/dhcp/dhcpv6"
+	"github.com/insomniacslk/dhcp/dhcpv6/server6"
+)
+
+func handler(conn net.PacketConn, peer net.Addr, m dhcpv6.DHCPv6) {
+	// this function will just print the received DHCPv6 message, without replying
+	log.Print(m.Summary())
+}
+
+func main() {
+	laddr := net.UDPAddr{
+		IP:   net.ParseIP("::1"),
+		Port: dhcpv6.DefaultServerPort,
+	}
+	server := server6.NewServer(laddr, handler)
+
+	defer server.Close()
+	if err := server.ActivateAndServe(); err != nil {
+		log.Panic(err)
+	}
+}
diff --git a/examples/server6/server6 b/examples/server6/server6
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+++ b/examples/server6/server6