make handshake and crypto internal packages

internal/crypto/cert_cache.go

@@ -0,0 +1,48 @@
+package crypto
+
+import (
+	"fmt"
+	"hash/fnv"
+
+	"github.com/hashicorp/golang-lru"
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+)
+
+var (
+	compressedCertsCache *lru.Cache
+)
+
+func getCompressedCert(chain [][]byte, pCommonSetHashes, pCachedHashes []byte) ([]byte, error) {
+	// Hash all inputs
+	hasher := fnv.New64a()
+	for _, v := range chain {
+		hasher.Write(v)
+	}
+	hasher.Write(pCommonSetHashes)
+	hasher.Write(pCachedHashes)
+	hash := hasher.Sum64()
+
+	var result []byte
+
+	resultI, isCached := compressedCertsCache.Get(hash)
+	if isCached {
+		result = resultI.([]byte)
+	} else {
+		var err error
+		result, err = compressChain(chain, pCommonSetHashes, pCachedHashes)
+		if err != nil {
+			return nil, err
+		}
+		compressedCertsCache.Add(hash, result)
+	}
+
+	return result, nil
+}
+
+func init() {
+	var err error
+	compressedCertsCache, err = lru.New(protocol.NumCachedCertificates)
+	if err != nil {
+		panic(fmt.Sprintf("fatal error in quic-go: could not create lru cache: %s", err.Error()))
+	}
+}