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Add WithTrustedCar() reader option #381

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merged 4 commits into from
Mar 6, 2023
Merged

Add WithTrustedCar() reader option #381

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72ca565
Add NextInsecure() method
hsanjuan Feb 27, 2023
b0c4055
Add TrustedCAR option to BlockReader (remove NextInsecure())
hsanjuan Feb 28, 2023
0f53819
Add test for TrustedCAR option
hsanjuan Mar 6, 2023
74ad50b
fix: apply suggestions from code review
rvagg Mar 6, 2023
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14 changes: 8 additions & 6 deletions v2/block_reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -120,13 +120,15 @@ func (br *BlockReader) Next() (blocks.Block, error) {
return nil, err
}

hashed, err := c.Prefix().Sum(data)
if err != nil {
return nil, err
}
if !br.opts.TrustedCAR {
hashed, err := c.Prefix().Sum(data)
if err != nil {
return nil, err
}

if !hashed.Equals(c) {
return nil, fmt.Errorf("mismatch in content integrity, expected: %s, got: %s", c, hashed)
if !hashed.Equals(c) {
return nil, fmt.Errorf("mismatch in content integrity, expected: %s, got: %s", c, hashed)
}
}

ss := uint64(c.ByteLen()) + uint64(len(data))
Expand Down
34 changes: 34 additions & 0 deletions v2/block_reader_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -179,6 +179,40 @@ func TestMaxSectionLength(t *testing.T) {
require.True(t, bytes.Equal(block, readBlock.RawData()))
}

func TestTrustedCAR(t *testing.T) {
// headerHex is the zero-roots CARv1 header
const headerHex = "11a265726f6f7473806776657273696f6e01"
headerBytes, _ := hex.DecodeString(headerHex)
// block of zeros
block := make([]byte, 5)
// CID for that block
pfx := cid.NewPrefixV1(cid.Raw, mh.SHA2_256)
cid, err := pfx.Sum(block)
require.NoError(t, err)

// Modify the block so it won't match CID anymore
block[2] = 0xFF
// construct CAR
var buf bytes.Buffer
buf.Write(headerBytes)
buf.Write(varint.ToUvarint(uint64(len(cid.Bytes()) + len(block))))
buf.Write(cid.Bytes())
buf.Write(block)

// try to read it as trusted
car, err := carv2.NewBlockReader(bytes.NewReader(buf.Bytes()), carv2.WithTrustedCAR(true))
require.NoError(t, err)
_, err = car.Next()
require.NoError(t, err)

// Try to read it as untrusted - should fail
car, err = carv2.NewBlockReader(bytes.NewReader(buf.Bytes()), carv2.WithTrustedCAR(false))
require.NoError(t, err)
// error should occur on first section read
_, err = car.Next()
require.EqualError(t, err, "mismatch in content integrity, expected: bafkreieikviivlpbn3cxhuq6njef37ikoysaqxa2cs26zxleqxpay2bzuq, got: bafkreidgklrppelx4fxcsna7cxvo3g7ayedfojkqeuus6kz6e4hy7gukmy")
}

func TestMaxHeaderLength(t *testing.T) {
// headerHex is the is a 5 root CARv1 header
const headerHex = "de01a265726f6f747385d82a58250001711220785197229dc8bb1152945da58e2348f7e279eeded06cc2ca736d0e879858b501d82a58250001711220785197229dc8bb1152945da58e2348f7e279eeded06cc2ca736d0e879858b501d82a58250001711220785197229dc8bb1152945da58e2348f7e279eeded06cc2ca736d0e879858b501d82a58250001711220785197229dc8bb1152945da58e2348f7e279eeded06cc2ca736d0e879858b501d82a58250001711220785197229dc8bb1152945da58e2348f7e279eeded06cc2ca736d0e879858b5016776657273696f6e01"
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9 changes: 9 additions & 0 deletions v2/options.go
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@ type Options struct {
MaxTraversalLinks uint64
WriteAsCarV1 bool
TraversalPrototypeChooser traversal.LinkTargetNodePrototypeChooser
TrustedCAR bool

MaxAllowedHeaderSize uint64
MaxAllowedSectionSize uint64
Expand Down Expand Up @@ -160,6 +161,14 @@ func WithTraversalPrototypeChooser(t traversal.LinkTargetNodePrototypeChooser) O
}
}

// WithTrustedCAR specifies whether CIDs match the block data as they are read
// from the CAR files.
func WithTrustedCAR(t bool) Option {
return func(o *Options) {
o.TrustedCAR = t
}
}

// MaxAllowedHeaderSize overrides the default maximum size (of 32 MiB) that a
// CARv1 decode (including within a CARv2 container) will allow a header to be
// without erroring.
Expand Down