u.Hash - error

the u.Hash error can be safely ignored (panic) because multihash
only fails from the selection of hash function. If the fn + length
are valid, it won't error.

cc @whyrusleeping

blocks/blocks.go

@@ -13,11 +13,7 @@ type Block struct {
 
 // NewBlock creates a Block object from opaque data. It will hash the data.
 func NewBlock(data []byte) (*Block, error) {
-	h, err := u.Hash(data)
-	if err != nil {
-		return nil, err
-	}
-	return &Block{Data: data, Multihash: h}, nil
+	return &Block{Data: data, Multihash: u.Hash(data)}, nil
 }
 
 // Key returns the block's Multihash as a Key value.

blockservice/blocks_test.go

@@ -23,12 +23,7 @@ func TestBlocks(t *testing.T) {
 		return
 	}
 
-	h, err := u.Hash([]byte("beep boop"))
-	if err != nil {
-		t.Error("failed to hash data", err)
-		return
-	}
-
+	h := u.Hash([]byte("beep boop"))
 	if !bytes.Equal(b.Multihash, h) {
 		t.Error("Block Multihash and data multihash not equal")
 	}

crypto/key.go

@@ -249,5 +249,5 @@ func KeyHash(k Key) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return u.Hash(kb)
+	return u.Hash(kb), nil
 }

crypto/spipe/handshake.go

@@ -292,25 +292,15 @@ func IDFromPubKey(pk ci.PubKey) (peer.ID, error) {
 	if err != nil {
 		return nil, err
 	}
-	hash, err := u.Hash(b)
-	if err != nil {
-		return nil, err
-	}
+	hash := u.Hash(b)
 	return peer.ID(hash), nil
 }
 
 // Determines which algorithm to use.  Note:  f(a, b) = f(b, a)
 func selectBest(myPrefs, theirPrefs string) (string, error) {
 	// Person with greatest hash gets first choice.
-	myHash, err := u.Hash([]byte(myPrefs))
-	if err != nil {
-		return "", err
-	}
-
-	theirHash, err := u.Hash([]byte(theirPrefs))
-	if err != nil {
-		return "", err
-	}
+	myHash := u.Hash([]byte(myPrefs))
+	theirHash := u.Hash([]byte(theirPrefs))
 
 	cmp := bytes.Compare(myHash, theirHash)
 	var firstChoiceArr, secChoiceArr []string

merkledag/merkledag.go

@@ -130,7 +130,7 @@ func (n *Node) Multihash() (mh.Multihash, error) {
 		return nil, err
 	}
 
-	return u.Hash(b)
+	return u.Hash(b), nil
 }
 
 // Key returns the Multihash as a key, for maps.

namesys/publisher.go

@@ -42,16 +42,9 @@ func (p *ipnsPublisher) Publish(k ci.PrivKey, value string) error {
 		return nil
 	}
 
-	nameb, err := u.Hash(pkbytes)
-	if err != nil {
-		return nil
-	}
+	nameb := u.Hash(pkbytes)
 	namekey := u.Key(nameb).Pretty()
-
-	ipnskey, err := u.Hash([]byte("/ipns/" + namekey))
-	if err != nil {
-		return err
-	}
+	ipnskey := u.Hash([]byte("/ipns/" + namekey))
 
 	// Store associated public key
 	timectx, _ := context.WithDeadline(ctx, time.Now().Add(time.Second*4))

namesys/resolve_test.go

@@ -48,11 +48,7 @@ func TestRoutingResolve(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	pkhash, err := u.Hash(pubkb)
-	if err != nil {
-		t.Fatal(err)
-	}
-
+	pkhash := u.Hash(pubkb)
 	res, err := resolve.Resolve(u.Key(pkhash).Pretty())
 	if err != nil {
 		t.Fatal(err)

namesys/routing.go

@@ -45,10 +45,7 @@ func (r *RoutingResolver) Resolve(name string) (string, error) {
 
 	// use the routing system to get the name.
 	// /ipns/<name>
-	h, err := u.Hash([]byte("/ipns/" + name))
-	if err != nil {
-		return "", err
-	}
+	h := u.Hash([]byte("/ipns/" + name))
 
 	ipnsKey := u.Key(h)
 	val, err := r.routing.GetValue(ctx, ipnsKey)

peer/queue/queue_test.go

@@ -68,7 +68,7 @@ func TestQueue(t *testing.T) {
 
 func newPeerTime(t time.Time) *peer.Peer {
 	s := fmt.Sprintf("hmmm time: %v", t)
-	h, _ := u.Hash([]byte(s))
+	h := u.Hash([]byte(s))
 	return &peer.Peer{ID: peer.ID(h)}
 }
 

util/util.go

@@ -54,8 +54,15 @@ func KeyFromDsKey(dsk ds.Key) Key {
 }
 
 // Hash is the global IPFS hash function. uses multihash SHA2_256, 256 bits
-func Hash(data []byte) (mh.Multihash, error) {
-	return mh.Sum(data, mh.SHA2_256, -1)
+func Hash(data []byte) mh.Multihash {
+	h, err := mh.Sum(data, mh.SHA2_256, -1)
+	if err != nil {
+		// this error can be safely ignored (panic) because multihash only fails
+		// from the selection of hash function. If the fn + length are valid, it
+		// won't error.
+		panic("multihash failed to hash using SHA2_256.")
+	}
+	return h
 }
 
 // IsValidHash checks whether a given hash is valid (b58 decodable, len > 0)