tls

func Marshal ¶

func Marshal(val interface{}) ([]byte, error)

Marshal returns the TLS encoding of val.

func MarshalWithParams ¶

func MarshalWithParams(val interface{}, params string) ([]byte, error)

MarshalWithParams returns the TLS encoding of val, and allows field parameters to be specified for the top-level element. The form of the params is the same as the field tags.

func Unmarshal ¶

func Unmarshal(b []byte, val interface{}) ([]byte, error)

Unmarshal parses the TLS-encoded data in b and uses the reflect package to fill in an arbitrary value pointed at by val. Because Unmarshal uses the reflect package, the structs being written to must use exported fields (upper case names).

The mappings between TLS types and Go types is as follows; some fields must have tags (to indicate their encoded size).

TLS		Go		Required Tags
opaque		byte / uint8
uint8		byte / uint8
uint16		uint16
uint24		tls.Uint24
uint32		uint32
uint64		uint64
enum		tls.Enum	size:S or maxval:N
Type<N,M>	[]Type		minlen:N,maxlen:M
opaque[N]	[N]byte / [N]uint8
uint8[N]	[N]byte / [N]uint8
struct { }	struct { }
select(T) {
 case e1: Type	*T		selector:Field,val:e1
}

TLS variants (RFC 5246 s4.6.1) are only supported when the value of the associated enumeration type is available earlier in the same enclosing struct, and each possible variant is marked with a selector tag (to indicate which field selects the variants) and a val tag (to indicate what value of the selector picks this particular field).

For example, a TLS structure:

enum { e1(1), e2(2) } EnumType;
struct {
   EnumType sel;
   select(sel) {
      case e1: uint16
      case e2: uint32
   } data;
} VariantItem;

would have a corresponding Go type:

type VariantItem struct {
   Sel    tls.Enum  `tls:"maxval:2"`
   Data16 *uint16   `tls:"selector:Sel,val:1"`
   Data32 *uint32   `tls:"selector:Sel,val:2"`
 }

TLS fixed-length vectors of types other than opaque or uint8 are not supported.

For TLS variable-length vectors that are themselves used in other vectors, create a single-field structure to represent the inner type. For example, for:

opaque InnerType<1..65535>;
struct {
  InnerType inners<1,65535>;
} Something;

convert to:

type InnerType struct {
   Val    []byte       `tls:"minlen:1,maxlen:65535"`
}
type Something struct {
   Inners []InnerType  `tls:"minlen:1,maxlen:65535"`
}

If the encoded value does not fit in the Go type, Unmarshal returns a parse error.

func UnmarshalWithParams ¶

func UnmarshalWithParams(b []byte, val interface{}, params string) ([]byte, error)

UnmarshalWithParams allows field parameters to be specified for the top-level element. The form of the params is the same as the field tags.