feat: provide public IP discovered from the server

Discovery Service provides public IP as seen by the server.

This public IP can be used to provide additional information to the
node.

Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>

pkg/client/client.go

@@ -71,6 +71,7 @@ type Client struct {
 
 	discoveredMu         sync.Mutex
 	discoveredAffiliates map[string]*Affiliate
+	discoveredPublicIP   []byte
 
 	gcm     cipher.AEAD
 	backoff *backoff.ExponentialBackOff
@@ -222,6 +223,14 @@ func (client *Client) GetAffiliates() []*Affiliate {
 	return result
 }
 
+// GetPublicIP returns client's discovered public IP.
+func (client *Client) GetPublicIP() []byte {
+	client.discoveredMu.Lock()
+	defer client.discoveredMu.Unlock()
+
+	return append([]byte(nil), client.discoveredPublicIP...)
+}
+
 // Run the client loop.
 //
 // Client automatically keeps the connection, refreshes data based on TTL.
@@ -470,6 +479,10 @@ func (client *Client) sendHello(ctx context.Context, discoveryClient serverpb.Cl
 		return "", err
 	}
 
+	client.discoveredMu.Lock()
+	client.discoveredPublicIP = resp.ClientIp
+	client.discoveredMu.Unlock()
+
 	if resp.Redirect != nil {
 		return resp.Redirect.Endpoint, nil
 	}