1// Amazon's application extension to TLVs for NLB VPC endpoint services
2// https://docs.aws.amazon.com/elasticloadbalancing/latest/network/load-balancer-target-groups.html#proxy-protocol
3
4package tlvparse
5
6import (
7	"regexp"
8
9	"github.com/pires/go-proxyproto"
10)
11
12const (
13	// Amazon's extension
14	PP2_TYPE_AWS            = 0xEA
15	PP2_SUBTYPE_AWS_VPCE_ID = 0x01
16)
17
18var vpceRe = regexp.MustCompile("^[A-Za-z0-9-]*$")
19
20func IsAWSVPCEndpointID(tlv proxyproto.TLV) bool {
21	return tlv.Type == PP2_TYPE_AWS && len(tlv.Value) > 0 && tlv.Value[0] == PP2_SUBTYPE_AWS_VPCE_ID
22}
23
24func AWSVPCEndpointID(tlv proxyproto.TLV) (string, error) {
25	if !IsAWSVPCEndpointID(tlv) {
26		return "", proxyproto.ErrIncompatibleTLV
27	}
28	vpce := string(tlv.Value[1:])
29	if !vpceRe.MatchString(vpce) {
30		return "", proxyproto.ErrMalformedTLV
31	}
32	return vpce, nil
33}
34
35// FindAWSVPCEndpointID returns the first AWS VPC ID in the TLV if it exists and is well-formed.
36func FindAWSVPCEndpointID(tlvs []proxyproto.TLV) string {
37	for _, tlv := range tlvs {
38		if vpc, err := AWSVPCEndpointID(tlv); err == nil && vpc != "" {
39			return vpc
40		}
41	}
42	return ""
43}
44