dhcpv4: Add go-fuzz endpoint

Signed-off-by: Anatole Denis <natolumin@unverle.fr>

1 files changed, 41 insertions, 0 deletions

diff --git a/dhcpv4/fuzz.go b/dhcpv4/fuzz.go
new file mode 100644
index 0000000..cf62ba5
--- /dev/null
+++ b/dhcpv4/fuzz.go
@@ -0,0 +1,41 @@
+// +build gofuzz
+
+package dhcpv4
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// Fuzz is the entrypoint for go-fuzz
+func Fuzz(data []byte) int {
+	msg, err := FromBytes(data)
+	if err != nil {
+		return 0
+	}
+
+	serialized := msg.ToBytes()
+
+	// Compared to dhcpv6, dhcpv4 has padding and fixed-size fields containing
+	// variable-length data; We can't expect the library to output byte-for-byte
+	// identical packets after a round-trip.
+	// Instead, we check that after a round-trip, the packet reserializes to the
+	// same internal representation
+	rtMsg, err := FromBytes(serialized)
+
+	if err != nil || !reflect.DeepEqual(msg, rtMsg) {
+		fmt.Printf("Input:      %x\n", data)
+		fmt.Printf("Round-trip: %x\n", serialized)
+		fmt.Println("Message: ", msg.Summary())
+		fmt.Printf("Go repr: %#v\n", msg)
+		fmt.Println("Reserialized: ", rtMsg.Summary())
+		fmt.Printf("Go repr: %#v\n", rtMsg)
+		if err != nil {
+			fmt.Printf("Got error while reserializing: %v\n", err)
+			panic("round-trip error: " + err.Error())
+		}
+		panic("round-trip different: " + msg.Summary())
+	}
+
+	return 1
+}