encoding/asn1: slice is lost during marshal/unmarshal

[Dmitry Vyukov]

The following program:

package main

import (
    "encoding/asn1"
    "fmt"
    "reflect"
)

func main() {
    data := []byte("\x06\x010")
    var v interface{}
    _, err := asn1.Unmarshal(data, &v)
    if err != nil {
        return
    }
    data1, err := asn1.Marshal(v)
    if err != nil {
        panic(err)
    }
    var v1 interface{}
    _, err = asn1.Unmarshal(data1, &v1)
    if err != nil {
        panic(err)
    }
    if !reflect.DeepEqual(v, v1) {
        fmt.Printf("v0: %#v data=%q\n", v, data)
        fmt.Printf("v1: %#v data=%q\n", v1, data1)
        panic("not equal")
    }
}

prints:

v0: []int{1, 8} data="\x06\x010"
v1: <nil> data="0\x06\x02\x01\x01\x02\x01\b"
panic: not equal

The slice should not get lost during marshal/unmarshal.

on commit b0532a9

[GopherBot]

Change https://golang.org/cl/113837 mentions this issue: encoding/asn1: fix returned type for an Object Identifier

[Constantin Konstantinidis]

Unmarshal/Marshal/Unmarshal was not idempotent as the Object Identifier type was not returned through the interface. The limit case OID = 0 returns an error. The zero OID is {0.0}

If bytes are transmitted to Marshal, a sequence of bytes is returned and not an OID and this is the intended behavior. Object Identifier is a list of int and the example submitted translates to
\x06\x010 = \x06\x01 + "0" which is OID {1,8} coded as \x06\x01\x30