v0.4.1

Co-authored-by: Rod Vagg <rod@vagg.org>

cid.go

@@ -37,10 +37,32 @@ import (
 // UnsupportedVersionString just holds an error message
 const UnsupportedVersionString = "<unsupported cid version>"
 
+// ErrInvalidCid is an error that indicates that a CID is invalid.
+type ErrInvalidCid struct {
+	Err error
+}
+
+func (e ErrInvalidCid) Error() string {
+	return fmt.Sprintf("invalid cid: %s", e.Err)
+}
+
+func (e ErrInvalidCid) Unwrap() error {
+	return e.Err
+}
+
+func (e ErrInvalidCid) Is(err error) bool {
+	switch err.(type) {
+	case ErrInvalidCid, *ErrInvalidCid:
+		return true
+	default:
+		return false
+	}
+}
+
 var (
 	// ErrCidTooShort means that the cid passed to decode was not long
 	// enough to be a valid Cid
-	ErrCidTooShort = errors.New("cid too short")
+	ErrCidTooShort = ErrInvalidCid{errors.New("cid too short")}
 
 	// ErrInvalidEncoding means that selected encoding is not supported
 	// by this Cid version
@@ -90,10 +112,10 @@ func tryNewCidV0(mhash mh.Multihash) (Cid, error) {
 	// incorrectly detect it as CidV1 in the Version() method
 	dec, err := mh.Decode(mhash)
 	if err != nil {
-		return Undef, err
+		return Undef, ErrInvalidCid{err}
 	}
 	if dec.Code != mh.SHA2_256 || dec.Length != 32 {
-		return Undef, fmt.Errorf("invalid hash for cidv0 %d-%d", dec.Code, dec.Length)
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid hash for cidv0 %d-%d", dec.Code, dec.Length)}
 	}
 	return Cid{string(mhash)}, nil
 }
@@ -177,7 +199,7 @@ func Parse(v interface{}) (Cid, error) {
 	case Cid:
 		return v2, nil
 	default:
-		return Undef, fmt.Errorf("can't parse %+v as Cid", v2)
+		return Undef, ErrInvalidCid{fmt.Errorf("can't parse %+v as Cid", v2)}
 	}
 }
 
@@ -210,7 +232,7 @@ func Decode(v string) (Cid, error) {
 	if len(v) == 46 && v[:2] == "Qm" {
 		hash, err := mh.FromB58String(v)
 		if err != nil {
-			return Undef, err
+			return Undef, ErrInvalidCid{err}
 		}
 
 		return tryNewCidV0(hash)
@@ -218,7 +240,7 @@ func Decode(v string) (Cid, error) {
 
 	_, data, err := mbase.Decode(v)
 	if err != nil {
-		return Undef, err
+		return Undef, ErrInvalidCid{err}
 	}
 
 	return Cast(data)
@@ -240,7 +262,7 @@ func ExtractEncoding(v string) (mbase.Encoding, error) {
 	// check encoding is valid
 	_, err := mbase.NewEncoder(encoding)
 	if err != nil {
-		return -1, err
+		return -1, ErrInvalidCid{err}
 	}
 
 	return encoding, nil
@@ -260,11 +282,11 @@ func ExtractEncoding(v string) (mbase.Encoding, error) {
 func Cast(data []byte) (Cid, error) {
 	nr, c, err := CidFromBytes(data)
 	if err != nil {
-		return Undef, err
+		return Undef, ErrInvalidCid{err}
 	}
 
 	if nr != len(data) {
-		return Undef, fmt.Errorf("trailing bytes in data buffer passed to cid Cast")
+		return Undef, ErrInvalidCid{fmt.Errorf("trailing bytes in data buffer passed to cid Cast")}
 	}
 
 	return c, nil
@@ -434,7 +456,7 @@ func (c Cid) Equals(o Cid) bool {
 // UnmarshalJSON parses the JSON representation of a Cid.
 func (c *Cid) UnmarshalJSON(b []byte) error {
 	if len(b) < 2 {
-		return fmt.Errorf("invalid cid json blob")
+		return ErrInvalidCid{fmt.Errorf("invalid cid json blob")}
 	}
 	obj := struct {
 		CidTarget string `json:"/"`
@@ -442,7 +464,7 @@ func (c *Cid) UnmarshalJSON(b []byte) error {
 	objptr := &obj
 	err := json.Unmarshal(b, &objptr)
 	if err != nil {
-		return err
+		return ErrInvalidCid{err}
 	}
 	if objptr == nil {
 		*c = Cid{}
@@ -450,12 +472,12 @@ func (c *Cid) UnmarshalJSON(b []byte) error {
 	}
 
 	if obj.CidTarget == "" {
-		return fmt.Errorf("cid was incorrectly formatted")
+		return ErrInvalidCid{fmt.Errorf("cid was incorrectly formatted")}
 	}
 
 	out, err := Decode(obj.CidTarget)
 	if err != nil {
-		return err
+		return ErrInvalidCid{err}
 	}
 
 	*c = out
@@ -542,12 +564,12 @@ func (p Prefix) Sum(data []byte) (Cid, error) {
 	if p.Version == 0 && (p.MhType != mh.SHA2_256 ||
 		(p.MhLength != 32 && p.MhLength != -1)) {
 
-		return Undef, fmt.Errorf("invalid v0 prefix")
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid v0 prefix")}
 	}
 
 	hash, err := mh.Sum(data, p.MhType, length)
 	if err != nil {
-		return Undef, err
+		return Undef, ErrInvalidCid{err}
 	}
 
 	switch p.Version {
@@ -556,7 +578,7 @@ func (p Prefix) Sum(data []byte) (Cid, error) {
 	case 1:
 		return NewCidV1(p.Codec, hash), nil
 	default:
-		return Undef, fmt.Errorf("invalid cid version")
+		return Undef, ErrInvalidCid{fmt.Errorf("invalid cid version")}
 	}
 }
 
@@ -586,22 +608,22 @@ func PrefixFromBytes(buf []byte) (Prefix, error) {
 	r := bytes.NewReader(buf)
 	vers, err := varint.ReadUvarint(r)
 	if err != nil {
-		return Prefix{}, err
+		return Prefix{}, ErrInvalidCid{err}
 	}
 
 	codec, err := varint.ReadUvarint(r)
 	if err != nil {
-		return Prefix{}, err
+		return Prefix{}, ErrInvalidCid{err}
 	}
 
 	mhtype, err := varint.ReadUvarint(r)
 	if err != nil {
-		return Prefix{}, err
+		return Prefix{}, ErrInvalidCid{err}
 	}
 
 	mhlen, err := varint.ReadUvarint(r)
 	if err != nil {
-		return Prefix{}, err
+		return Prefix{}, ErrInvalidCid{err}
 	}
 
 	return Prefix{
@@ -615,12 +637,12 @@ func PrefixFromBytes(buf []byte) (Prefix, error) {
 func CidFromBytes(data []byte) (int, Cid, error) {
 	if len(data) > 2 && data[0] == mh.SHA2_256 && data[1] == 32 {
 		if len(data) < 34 {
-			return 0, Undef, fmt.Errorf("not enough bytes for cid v0")
+			return 0, Undef, ErrInvalidCid{fmt.Errorf("not enough bytes for cid v0")}
 		}
 
 		h, err := mh.Cast(data[:34])
 		if err != nil {
-			return 0, Undef, err
+			return 0, Undef, ErrInvalidCid{err}
 		}
 
 		return 34, Cid{string(h)}, nil
@@ -628,21 +650,21 @@ func CidFromBytes(data []byte) (int, Cid, error) {
 
 	vers, n, err := varint.FromUvarint(data)
 	if err != nil {
-		return 0, Undef, err
+		return 0, Undef, ErrInvalidCid{err}
 	}
 
 	if vers != 1 {
-		return 0, Undef, fmt.Errorf("expected 1 as the cid version number, got: %d", vers)
+		return 0, Undef, ErrInvalidCid{fmt.Errorf("expected 1 as the cid version number, got: %d", vers)}
 	}
 
 	_, cn, err := varint.FromUvarint(data[n:])
 	if err != nil {
-		return 0, Undef, err
+		return 0, Undef, ErrInvalidCid{err}
 	}
 
 	mhnr, _, err := mh.MHFromBytes(data[n+cn:])
 	if err != nil {
-		return 0, Undef, err
+		return 0, Undef, ErrInvalidCid{err}
 	}
 
 	l := n + cn + mhnr
@@ -695,6 +717,9 @@ func (r *bufByteReader) ReadByte() (byte, error) {
 // It's recommended to supply a reader that buffers and implements io.ByteReader,
 // as CidFromReader has to do many single-byte reads to decode varints.
 // If the argument only implements io.Reader, single-byte Read calls are used instead.
+//
+// If the Reader is found to yield zero bytes, an io.EOF error is returned directly, in all
+// other error cases, an ErrInvalidCid, wrapping the original error, is returned.
 func CidFromReader(r io.Reader) (int, Cid, error) {
 	// 64 bytes is enough for any CIDv0,
 	// and it's enough for most CIDv1s in practice.
@@ -705,32 +730,37 @@ func CidFromReader(r io.Reader) (int, Cid, error) {
 	// The varint package wants a io.ByteReader, so we must wrap our io.Reader.
 	vers, err := varint.ReadUvarint(br)
 	if err != nil {
-		return len(br.dst), Undef, err
+		if err == io.EOF {
+			// First-byte read in ReadUvarint errors with io.EOF, so reader has no data.
+			// Subsequent reads with an EOF will return io.ErrUnexpectedEOF and be wrapped here.
+			return 0, Undef, err
+		}
+		return len(br.dst), Undef, ErrInvalidCid{err}
 	}
 
 	// If we have a CIDv0, read the rest of the bytes and cast the buffer.
 	if vers == mh.SHA2_256 {
 		if n, err := io.ReadFull(r, br.dst[1:34]); err != nil {
-			return len(br.dst) + n, Undef, err
+			return len(br.dst) + n, Undef, ErrInvalidCid{err}
 		}
 
 		br.dst = br.dst[:34]
 		h, err := mh.Cast(br.dst)
 		if err != nil {
-			return len(br.dst), Undef, err
+			return len(br.dst), Undef, ErrInvalidCid{err}
 		}
 
 		return len(br.dst), Cid{string(h)}, nil
 	}
 
 	if vers != 1 {
-		return len(br.dst), Undef, fmt.Errorf("expected 1 as the cid version number, got: %d", vers)
+		return len(br.dst), Undef, ErrInvalidCid{fmt.Errorf("expected 1 as the cid version number, got: %d", vers)}
 	}
 
 	// CID block encoding multicodec.
 	_, err = varint.ReadUvarint(br)
 	if err != nil {
-		return len(br.dst), Undef, err
+		return len(br.dst), Undef, ErrInvalidCid{err}
 	}
 
 	// We could replace most of the code below with go-multihash's ReadMultihash.
@@ -741,19 +771,19 @@ func CidFromReader(r io.Reader) (int, Cid, error) {
 	// Multihash hash function code.
 	_, err = varint.ReadUvarint(br)
 	if err != nil {
-		return len(br.dst), Undef, err
+		return len(br.dst), Undef, ErrInvalidCid{err}
 	}
 
 	// Multihash digest length.
 	mhl, err := varint.ReadUvarint(br)
 	if err != nil {
-		return len(br.dst), Undef, err
+		return len(br.dst), Undef, ErrInvalidCid{err}
 	}
 
 	// Refuse to make large allocations to prevent OOMs due to bugs.
 	const maxDigestAlloc = 32 << 20 // 32MiB
 	if mhl > maxDigestAlloc {
-		return len(br.dst), Undef, fmt.Errorf("refusing to allocate %d bytes for a digest", mhl)
+		return len(br.dst), Undef, ErrInvalidCid{fmt.Errorf("refusing to allocate %d bytes for a digest", mhl)}
 	}
 
 	// Fine to convert mhl to int, given maxDigestAlloc.
@@ -772,7 +802,7 @@ func CidFromReader(r io.Reader) (int, Cid, error) {
 	if n, err := io.ReadFull(r, br.dst[prefixLength:cidLength]); err != nil {
 		// We can't use len(br.dst) here,
 		// as we've only read n bytes past prefixLength.
-		return prefixLength + n, Undef, err
+		return prefixLength + n, Undef, ErrInvalidCid{err}
 	}
 
 	// This simply ensures the multihash is valid.
@@ -780,7 +810,7 @@ func CidFromReader(r io.Reader) (int, Cid, error) {
 	// for now, it helps ensure consistency with CidFromBytes.
 	_, _, err = mh.MHFromBytes(br.dst[mhStart:])
 	if err != nil {
-		return len(br.dst), Undef, err
+		return len(br.dst), Undef, ErrInvalidCid{err}
 	}
 
 	return len(br.dst), Cid{string(br.dst)}, nil

cid_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	crand "crypto/rand"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math/rand"
@@ -162,6 +163,9 @@ func TestBasesMarshaling(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected too-short error from ExtractEncoding")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 	if ee != -1 {
 		t.Fatal("expected -1 from too-short ExtractEncoding")
 	}
@@ -227,6 +231,9 @@ func TestEmptyString(t *testing.T) {
 	if err == nil {
 		t.Fatal("shouldnt be able to parse an empty cid")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("error must be ErrInvalidCid")
+	}
 }
 
 func TestV0Handling(t *testing.T) {
@@ -282,6 +289,9 @@ func TestV0ErrorCases(t *testing.T) {
 	if err == nil {
 		t.Fatal("should have failed to decode that ref")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("error must be ErrInvalidCid")
+	}
 }
 
 func TestNewPrefixV1(t *testing.T) {
@@ -372,6 +382,9 @@ func TestInvalidV0Prefix(t *testing.T) {
 		if err == nil {
 			t.Fatalf("should error (index %d)", i)
 		}
+		if !errors.Is(err, ErrInvalidCid{}) {
+			t.Fatal("expected error to be ErrInvalidCid")
+		}
 	}
 }
 
@@ -381,6 +394,9 @@ func TestBadPrefix(t *testing.T) {
 	if err == nil {
 		t.Fatalf("expected error on v3 prefix Sum")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 }
 
 func TestPrefixRoundtrip(t *testing.T) {
@@ -417,18 +433,30 @@ func TestBadPrefixFromBytes(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for bad byte 0")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 	_, err = PrefixFromBytes([]byte{0x01, 0x80})
 	if err == nil {
 		t.Fatal("expected error for bad byte 1")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 	_, err = PrefixFromBytes([]byte{0x01, 0x01, 0x80})
 	if err == nil {
 		t.Fatal("expected error for bad byte 2")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 	_, err = PrefixFromBytes([]byte{0x01, 0x01, 0x01, 0x80})
 	if err == nil {
 		t.Fatal("expected error for bad byte 3")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 }
 
 func Test16BytesVarint(t *testing.T) {
@@ -455,6 +483,9 @@ func TestParse(t *testing.T) {
 	if !strings.Contains(err.Error(), "can't parse 123 as Cid") {
 		t.Fatalf("expected int error, got %s", err.Error())
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatalf("expected ErrInvalidCid, got %s", err.Error())
+	}
 
 	theHash := "QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n"
 	h, err := mh.FromB58String(theHash)
@@ -572,17 +603,29 @@ func TestJsonRoundTrip(t *testing.T) {
 		t.Fatal("cids not equal for Cid")
 	}
 
-	if err = actual2.UnmarshalJSON([]byte("1")); err == nil {
+	err = actual2.UnmarshalJSON([]byte("1"))
+	if err == nil {
 		t.Fatal("expected error for too-short JSON")
 	}
-
-	if err = actual2.UnmarshalJSON([]byte(`{"nope":"nope"}`)); err == nil {
-		t.Fatal("expected error for bad CID JSON")
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
 	}
 
-	if err = actual2.UnmarshalJSON([]byte(`bad "" json!`)); err == nil {
+	err = actual2.UnmarshalJSON([]byte(`{"nope":"nope"}`))
+	if err == nil {
+		t.Fatal("expected error for bad CID JSON")
+	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
+
+	err = actual2.UnmarshalJSON([]byte(`bad "" json!`))
+	if err == nil {
 		t.Fatal("expected error for bad JSON")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("expected error to be ErrInvalidCid")
+	}
 
 	var actual3 Cid
 	enc, err = actual3.MarshalJSON()
@@ -740,6 +783,30 @@ func TestBadCidInput(t *testing.T) {
 	}
 }
 
+func TestFromReaderNoData(t *testing.T) {
+	// Reading no data from io.Reader should return io.EOF, not ErrInvalidCid.
+	n, cid, err := CidFromReader(bytes.NewReader(nil))
+	if err != io.EOF {
+		t.Fatal("Expected io.EOF error")
+	}
+	if cid != Undef {
+		t.Fatal("Expected Undef CID")
+	}
+	if n != 0 {
+		t.Fatal("Expected 0 data")
+	}
+
+	// Read byte indicatiing more data to and check error is ErrInvalidCid.
+	_, _, err = CidFromReader(bytes.NewReader([]byte{0x80}))
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("Expected ErrInvalidCid error")
+	}
+	// Check for expected wrapped error.
+	if !errors.Is(err, io.ErrUnexpectedEOF) {
+		t.Fatal("Expected error", io.ErrUnexpectedEOF)
+	}
+}
+
 func TestBadParse(t *testing.T) {
 	hash, err := mh.Sum([]byte("foobar"), mh.SHA3_256, -1)
 	if err != nil {
@@ -749,6 +816,9 @@ func TestBadParse(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected to fail to parse an invalid CIDv1 CID")
 	}
+	if !errors.Is(err, ErrInvalidCid{}) {
+		t.Fatal("error must be ErrInvalidCid")
+	}
 }
 
 func TestLoggable(t *testing.T) {
@@ -763,3 +833,80 @@ func TestLoggable(t *testing.T) {
 		t.Fatalf("did not get expected loggable form (got %v)", actual)
 	}
 }
+
+func TestErrInvalidCidIs(t *testing.T) {
+	for i, test := range []struct {
+		err    error
+		target error
+	}{
+		{&ErrInvalidCid{}, ErrInvalidCid{}},
+		{ErrInvalidCid{}, &ErrInvalidCid{}},
+		{ErrInvalidCid{}, ErrInvalidCid{}},
+		{&ErrInvalidCid{}, &ErrInvalidCid{}},
+	} {
+		if !errors.Is(test.err, test.target) {
+			t.Fatalf("expected error to be ErrInvalidCid, case %d", i)
+		}
+	}
+}
+
+func TestErrInvalidCid(t *testing.T) {
+	run := func(err error) {
+		if err == nil {
+			t.Fatal("expected error")
+		}
+
+		if !strings.HasPrefix(err.Error(), "invalid cid: ") {
+			t.Fatal(`expected error message to contain "invalid cid: "`)
+		}
+
+		is := errors.Is(err, ErrInvalidCid{})
+		if !is {
+			t.Fatal("expected error to be ErrInvalidCid")
+		}
+
+		if !errors.Is(err, &ErrInvalidCid{}) {
+			t.Fatal("expected error to be &ErrInvalidCid")
+		}
+	}
+
+	_, err := Decode("")
+	run(err)
+
+	_, err = Decode("not-a-cid")
+	run(err)
+
+	_, err = Decode("bafyInvalid")
+	run(err)
+
+	_, err = Decode("QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zIII")
+	run(err)
+
+	_, err = Cast([]byte("invalid"))
+	run(err)
+
+	_, err = Parse("not-a-cid")
+	run(err)
+
+	_, err = Parse("bafyInvalid")
+	run(err)
+
+	_, err = Parse("QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zIII")
+	run(err)
+
+	_, err = Parse(123)
+	run(err)
+
+	_, _, err = CidFromBytes([]byte("invalid"))
+	run(err)
+
+	_, err = Prefix{}.Sum([]byte("data"))
+	run(err)
+
+	_, err = PrefixFromBytes([]byte{0x80})
+	run(err)
+
+	_, err = ExtractEncoding("invalid ")
+	run(err)
+
+}

version.json

@@ -1,3 +1,3 @@
 {
-  "version": "v0.3.2"
+  "version": "v0.4.1"
 }