Add fuzzer

Signed-off-by: Alexey Palazhchenko <[email protected]>

Author: AlekSi

protocol/handler_fuzz.go

@@ -2,6 +2,63 @@
 
 package protocol
 
+import (
+	"bytes"
+	"encoding/hex"
+	"io"
+	"log"
+	"strings"
+
+	"github.com/GopherConRu/pb-fuzz-workshop/kv"
+)
+
 func Fuzz(data []byte) int {
-	return 0
+	kv, err := kv.NewInMemoryBadgerKV()
+	if err != nil {
+		panic(err)
+	}
+	defer func() {
+		if err := kv.Close(); err != nil {
+			panic(err)
+		}
+	}()
+
+	h := NewHandler(kv)
+	input, output := h.NewConn()
+
+	cmds := strings.Split(string(data), "\n")
+	cmds = append(cmds, "PING")
+
+	readDone := make(chan int)
+	go func() {
+		b, err := io.ReadAll(output)
+		if err != nil {
+			panic(err)
+		}
+
+		if !bytes.HasSuffix(b, []byte("+PONG\n")) {
+			log.Printf("Input: %q", cmds)
+			log.Printf("Output: %q", strings.Split(string(b), "\n"))
+			panic("Raw output:\n" + hex.Dump(b))
+		}
+
+		if bytes.Contains(b, []byte("-ERR")) {
+			readDone <- 0
+			return
+		}
+
+		readDone <- 1
+	}()
+
+	for _, cmd := range cmds {
+		if _, err := input.Write([]byte(cmd + "\n")); err != nil {
+			panic(err)
+		}
+	}
+
+	if err := input.Close(); err != nil {
+		panic(err)
+	}
+
+	return <-readDone
 }