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package netlink_test
import (
"fmt"
"log"
"github.com/mdlayher/netlink"
)
// decodeNested is a nested structure within decodeOut.
type decodeNested struct {
A, B uint32
}
// decodeOut is an example structure we will use to unpack netlink attributes.
type decodeOut struct {
Number uint16
String string
Nested decodeNested
}
// decode is an example function used to adapt the ad.Nested method to decode an
// arbitrary structure.
func (n *decodeNested) decode(ad *netlink.AttributeDecoder) error {
// Iterate over the attributes, checking the type of each attribute and
// decoding them as appropriate.
for ad.Next() {
switch ad.Type() {
// A and B are both uint32 values, so decode them as such.
case 1:
n.A = ad.Uint32()
case 2:
n.B = ad.Uint32()
}
}
// No need to call ad.Err directly.
return nil
}
// This example demonstrates using a netlink.AttributeDecoder to decode packed
// netlink attributes in a message payload.
func ExampleAttributeDecoder_decode() {
// Create a netlink.AttributeDecoder using some example attribute bytes
// that are prepared for this example.
ad, err := netlink.NewAttributeDecoder(exampleAttributes())
if err != nil {
log.Fatalf("failed to create attribute decoder: %v", err)
}
// Iterate attributes until completion, checking the type of each and
// decoding them as appropriate.
var out decodeOut
for ad.Next() {
// Check the type of the current attribute with ad.Type. Typically you
// will find netlink attribute types and data values in C headers as
// constants.
switch ad.Type() {
case 1:
// Number is a uint16.
out.Number = ad.Uint16()
case 2:
// String is a string.
out.String = ad.String()
case 3:
// Nested is a nested structure, so we will use a method on the
// nested type along with ad.Do to decode it in a concise way.
ad.Nested(out.Nested.decode)
}
}
// Any errors encountered during decoding (including any errors from
// decoding the nested attributes) will be returned here.
if err := ad.Err(); err != nil {
log.Fatalf("failed to decode attributes: %v", err)
}
fmt.Printf(`Number: %d
String: %q
Nested:
- A: %d
- B: %d`,
out.Number, out.String, out.Nested.A, out.Nested.B,
)
// Output:
// Number: 1
// String: "hello world"
// Nested:
// - A: 2
// - B: 3
}
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