v/vlib/x/encoding/asn1/examples/examples0.v

114 lines
3.7 KiB
V

module main
import x.encoding.asn1
// Previously, defined type KerberosString = asn1.GeneralString directly
// without reduplicating required Element methods, would produces
// RUNTIME ERROR: invalid memory access.
// **Updates**
// Its has been resolved in [22901](https://github.com/vlang/v/issues/22901)
// Thanks to @felipensp
type KerberosString = asn1.GeneralString
fn KerberosString.new(s string) !KerberosString {
return KerberosString(asn1.GeneralString.new(s)!)
}
type KerberosStringList = []KerberosString
fn (ksl KerberosStringList) tag() asn1.Tag {
return asn1.default_sequence_tag
}
fn (ksl KerberosStringList) payload() ![]u8 {
mut out := []u8{}
for item in ksl {
// maybe produces x00000000: at ???: RUNTIME ERROR: invalid memory access
// `item` cannot be used as interface object outside `unsafe` blocks as it
// might be stored on stack. Consider declaring `KerberosString` as `@[heap]`
obj := unsafe { item }
out << asn1.encode(obj)!
}
return out
}
// PrincipalName ::= SEQUENCE {
// name-type [0] Int32,
// name-string [1] SEQUENCE OF KerberosString
// }
struct PrincipalName {
name_type asn1.Integer @[context_specific: 0; explicit; inner: 2] // integer tag = (universal, false, 2)
// defines name_string as asn1.SequenceOf[KerberosString] would produces unexpected result
// when you build payload with `asn1.make_payload`,
// see issues at https://github.com/vlang/v/issues/22721
// so we build with KerberosStringList
name_string KerberosStringList @[context_specific: 1; explicit; inner: 16] // sequence tag = (universal, true, 16)
}
fn (pn PrincipalName) tag() asn1.Tag {
return asn1.default_sequence_tag
}
fn (pn PrincipalName) payload() ![]u8 {
kd := asn1.new_key_default()
payload := asn1.make_payload[PrincipalName](pn, kd)!
return payload
}
fn PrincipalName.decode(bytes []u8) !PrincipalName {
// decode should produces Sequence type
elem := asn1.decode(bytes)!
assert elem.tag().equal(asn1.default_sequence_tag)
// cast it into Sequence type and get the fields
seq := elem.into_object[asn1.Sequence]()!
fields := seq.fields()
// every fields of the sequence is raw of wrapped element, so we should unwrap it with
// the same options used to wrap in encode step, and turn to the real underlying object.
el_name_type := fields[0].unwrap_with_options('context_specific: 0; explicit; inner: 2')!
name_type := el_name_type.into_object[asn1.Integer]()!
// tag 16 is sequence tag, its decoded into Sequence type
el_name_string := fields[1].unwrap_with_options('context_specific: 1; explicit; inner: 16')!
el_seq := el_name_string.into_object[asn1.Sequence]()!
// KerberosString string has a general_string tag, so it would be parsed as asn1.GeneralString
// so, we transforms it into KerberosString back and build KerberosStringList.
mut a := []KerberosString{}
for item in el_seq.fields() {
gst := item.into_object[asn1.GeneralString]()!
obj := KerberosString(gst)
a << obj
}
name_string_list := KerberosStringList(a)
return PrincipalName{
name_type: name_type
name_string: name_string_list
}
}
fn main() {
// Basically this is a Kerberos PrincipalName data
data := [u8(0x30), 0x15, 0xa0, 0x03, 0x02, 0x01, 0x01, 0xa1, 0x0e, 0x30, 0x0c, 0x1b, 0x0a,
0x62, 0x6f, 0x62, 0x62, 0x61, 0x2d, 0x66, 0x65, 0x74, 0x74]
els := [KerberosString.new('bobba-fett')!]
pn := PrincipalName{
name_type: asn1.Integer.from_int(1)
name_string: KerberosStringList(els)
}
out1 := asn1.encode(pn)!
back := PrincipalName.decode(data)!
dump(back == pn) // should assert to true
dump(out1.hex() == data.hex()) // should assert to true
// run this produces:
// [examples/examples_0.v:128] back == pn: true
// [examples/examples_0.v:129] out1.hex() == data.hex(): true
}