CBOR is a concise binary alternative to JSON. This library makes CBOR easy to use.
This library is designed to be:
- Easy -- idiomatic API like
encoding/json. - Safe and reliable -- no
unsafepkg, test coverage at ~90%, and 10+ hrs of fuzzing with RFC 7049 test vectors. - Standards-compliant -- supports RFC 7049 and canonical CBOR encodings (both RFC 7049 and CTAP2).
- Small and self-contained -- pkg compiles to under 0.5 MB with no external dependencies.
cbor balances speed, safety (no unsafe pkg) and compiled size. To keep size small, it doesn't use code generation. For speed, it caches struct field types, bypasses reflect when appropriate, and uses sync.Pool to reuse transient objects.
Sept 11, 2019: Current version is expected to be released as 1.0 this month unless changes are requested by the Go community. It passed 10+ hours of fuzzing and appears to be ready for production use on linux_amd64.
Program size comparison (linux_amd64, Go 1.12) doing the same CBOR encoding and decoding:
- 2.6 MB program using fxamacker/cbor
- 11.9 MB program using ugorji/go
Library size comparison (linux_amd64, Go 1.12):
- 0.45 MB pkg -- fxamacker/cbor
- 2.9 MB pkg -- ugorji/go without code generation (
go install --tags "notfastpath") - 5.7 MB pkg -- ugorji/go with code generation (default build)
- Idiomatic API as in
jsonpackage. - No external dependencies.
- No use of
unsafepackage. - Tested with RFC 7049 test vectors.
- Test coverage at ~90%, and fuzzed 9+ hours using cbor-fuzz.
- Decode slices, maps, and structs in-place.
- Decode into struct with field name case-insensitive match.
- Support canonical CBOR encoding for map/struct.
- Support both "cbor" and "json" keys for struct field format tags.
- Encode anonymous struct fields by
jsonpackage struct fields visibility rules. - Encode and decode nil slice/map/pointer/interface values correctly.
- Encode and decode indefinite length bytes/string/array/map ("streaming").
- Encode and decode time.Time as RFC 3339 formatted text string or Unix time.
This library implements CBOR as specified in RFC 7049, with minor limitations.
It also supports canonical CBOR encodings (both RFC 7049 and CTAP2). CTAP2 canonical CBOR encoding is used by CTAP and WebAuthn in FIDO2 framework.
- This package doesn't support CBOR tag encoding.
- Decoder ignores CBOR tag and decodes tagged data following the tag.
- Signed integer values incompatible with Go's int64 are not supported.
- RFC 7049 test vectors with signed integer values incompatible with Go's int64 are skipped. For example, the signed integer result -18446744073709551616 is incompatible with Go's int64 data type (cannot be assigned without overflow).
This project uses Semantic Versioning, so the API is always backwards compatible unless the major version number changes.
See API docs for more details.
package cbor // import "github.com/fxamacker/cbor"
func Marshal(v interface{}, encOpts EncOptions) ([]byte, error)
func Unmarshal(data []byte, v interface{}) error
func Valid(data []byte) (rest []byte, err error)
type Decoder struct{ ... }
func NewDecoder(r io.Reader) *Decoder
func (dec *Decoder) Decode(v interface{}) (err error)
func (dec *Decoder) NumBytesRead() int
type EncOptions struct{ ... }
type Encoder struct{ ... }
func NewEncoder(w io.Writer, encOpts EncOptions) *Encoder
func (enc *Encoder) Encode(v interface{}) error
func (enc *Encoder) StartIndefiniteByteString() error
func (enc *Encoder) StartIndefiniteTextString() error
func (enc *Encoder) StartIndefiniteArray() error
func (enc *Encoder) StartIndefiniteMap() error
func (enc *Encoder) EndIndefinite() error
type InvalidUnmarshalError struct{ ... }
type InvalidValueError struct{ ... }
type SemanticError struct{ ... }
type SyntaxError struct{ ... }
type UnmarshalTypeError struct{ ... }
type UnsupportedTypeError struct{ ... }
go get github.com/fxamacker/cbor
See examples.
Using decoder:
// create a decoder
dec := cbor.NewDecoder(reader)
// decode into empty interface
var i interface{}
err = dec.Decode(&i)
// decode into struct
var stru ExampleStruct
err = dec.Decode(&stru)
// decode into map
var m map[string]string
err = dec.Decode(&m)
// decode into primitives
var f float32
err = dec.Decode(&f)
Using encoder:
// create an encoder with canonical CBOR encoding enabled
enc := cbor.NewEncoder(writer, cbor.EncOptions{Canonical: true})
// encode struct
err = enc.Encode(stru)
// encode map
err = enc.Encode(m)
// encode primitives
err = enc.Encode(f)
Encoding indefinite length array:
enc := cbor.NewEncoder(writer, cbor.EncOptions{})
// start indefinite length array encoding
err = enc.StartIndefiniteArray()
// encode array element
err = enc.Encode(1)
// encode array element
err = enc.Encode([]int{2, 3})
// start nested indefinite length array as array element
err = enc.StartIndefiniteArray()
// encode nested array element
err = enc.Encode(4)
// encode nested array element
err = enc.Encode(5)
// close nested indefinite length array
err = enc.EndIndefinite()
// close outer indefinite length array
err = enc.EndIndefinite()
See bench_test.go.
Unmarshal benchmarks are made on CBOR data representing the following values:
- Boolean:
true - Positive integer:
18446744073709551615 - Negative integer:
-1000 - Float:
-4.1 - Byte string:
h'0102030405060708090a0b0c0d0e0f101112131415161718191a' - Text string:
"The quick brown fox jumps over the lazy dog" - Array:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26] - Map:
{"a": "A", "b": "B", "c": "C", "d": "D", "e": "E", "f": "F", "g": "G", "h": "H", "i": "I", "j": "J", "l": "L", "m": "M", "n": "N"}}
Marshal benchmarks are made on Go values representing the same values.
Benchmarks shows that decoding into struct is >50% faster than decoding into map, and encoding struct is >70% faster than encoding map.
BenchmarkUnmarshal/CBOR_boolean_to_Go_interface_{}-2 10000000 132 ns/op 16 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_boolean_to_Go_bool-2 20000000 76.1 ns/op 1 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_positive_integer_to_Go_interface_{}-2 10000000 159 ns/op 24 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_positive_integer_to_Go_uint64-2 20000000 82.3 ns/op 8 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_negative_integer_to_Go_interface_{}-2 10000000 160 ns/op 24 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_negative_integer_to_Go_int64-2 20000000 83.8 ns/op 8 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_float_to_Go_interface_{}-2 10000000 159 ns/op 24 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_float_to_Go_float64-2 20000000 81.4 ns/op 8 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_byte_string_to_Go_interface_{}-2 10000000 214 ns/op 80 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_byte_string_to_Go_[]uint8-2 10000000 159 ns/op 64 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_byte_string_indefinite_length_to_Go_interface_{}-2 2000000 738 ns/op 112 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_byte_string_indefinite_length_to_Go_[]uint8-2 2000000 687 ns/op 96 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_text_string_to_Go_interface_{}-2 5000000 248 ns/op 80 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_text_string_to_Go_string-2 10000000 176 ns/op 64 B/op 2 allocs/op
BenchmarkUnmarshal/CBOR_text_string_indefinite_length_to_Go_interface_{}-2 1000000 1147 ns/op 144 B/op 4 allocs/op
BenchmarkUnmarshal/CBOR_text_string_indefinite_length_to_Go_string-2 1000000 1075 ns/op 128 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_array_to_Go_interface_{}-2 1000000 1156 ns/op 672 B/op 29 allocs/op
BenchmarkUnmarshal/CBOR_array_to_Go_[]int-2 1000000 1075 ns/op 272 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_array_indefinite_length_to_Go_interface_{}-2 1000000 1347 ns/op 672 B/op 29 allocs/op
BenchmarkUnmarshal/CBOR_array_indefinite_length_to_Go_[]int-2 1000000 1275 ns/op 272 B/op 3 allocs/op
BenchmarkUnmarshal/CBOR_map_to_Go_interface_{}-2 500000 3094 ns/op 1420 B/op 30 allocs/op
BenchmarkUnmarshal/CBOR_map_to_Go_map[string]interface_{}-2 300000 4064 ns/op 964 B/op 19 allocs/op
BenchmarkUnmarshal/CBOR_map_to_Go_map[string]string-2 500000 2808 ns/op 740 B/op 5 allocs/op
BenchmarkUnmarshal/CBOR_map_to_Go_cbor_test.strc-2 1000000 1624 ns/op 208 B/op 1 allocs/op
BenchmarkUnmarshal/CBOR_map_indefinite_length_to_Go_interface_{}-2 300000 4236 ns/op 2607 B/op 33 allocs/op
BenchmarkUnmarshal/CBOR_map_indefinite_length_to_Go_map[string]interface_{}-2 300000 5819 ns/op 2422 B/op 22 allocs/op
BenchmarkUnmarshal/CBOR_map_indefinite_length_to_Go_map[string]string-2 300000 4268 ns/op 2183 B/op 7 allocs/op
BenchmarkUnmarshal/CBOR_map_indefinite_length_to_Go_cbor_test.strc-2 1000000 1860 ns/op 208 B/op 1 allocs/op
BenchmarkMarshal/Go_bool_to_CBOR_boolean-2 20000000 62.8 ns/op 1 B/op 1 allocs/op
BenchmarkMarshal/Go_uint64_to_CBOR_positive_integer-2 20000000 73.4 ns/op 16 B/op 1 allocs/op
BenchmarkMarshal/Go_int64_to_CBOR_negative_integer-2 20000000 64.7 ns/op 3 B/op 1 allocs/op
BenchmarkMarshal/Go_float64_to_CBOR_float-2 20000000 70.4 ns/op 16 B/op 1 allocs/op
BenchmarkMarshal/Go_[]uint8_to_CBOR_byte_string-2 20000000 105 ns/op 32 B/op 1 allocs/op
BenchmarkMarshal/Go_string_to_CBOR_text_string-2 20000000 95.0 ns/op 48 B/op 1 allocs/op
BenchmarkMarshal/Go_[]int_to_CBOR_array-2 3000000 599 ns/op 32 B/op 1 allocs/op
BenchmarkMarshal/Go_map[string]string_to_CBOR_map-2 500000 3276 ns/op 576 B/op 28 allocs/op
BenchmarkMarshal/Go_cbor_test.strc_to_CBOR_map-2 2000000 868 ns/op 64 B/op 1 allocs/op
Copyright (c) 2019 Faye Amacker
Licensed under MIT License
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