UDP protocol on connect agnhost command

build/dependencies.yaml

@@ -1,7 +1,7 @@
 dependencies:
   # agnhost: bump this one first
   - name: "agnhost"
-    version: "2.27"
+    version: "2.28"
     refPaths:
     - path: test/images/agnhost/VERSION
       match: \d.\d

test/images/agnhost/VERSION

@@ -1 +1 @@
-2.27
+2.28

test/images/agnhost/agnhost.go

@@ -51,7 +51,7 @@ import (
 func main() {
 	rootCmd := &cobra.Command{
 		Use:     "app",
-		Version: "2.27",
+		Version: "2.28",
 	}
 
 	rootCmd.AddCommand(auditproxy.CmdAuditProxy)

test/images/agnhost/connect/connect.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"strings"
 	"syscall"
 	"time"
 
@@ -30,8 +31,8 @@ import (
 // CmdConnect is used by agnhost Cobra.
 var CmdConnect = &cobra.Command{
 	Use:   "connect [host:port]",
-	Short: "Attempts a TCP or SCTP connection and returns useful errors",
-	Long: `Tries to open a TCP or SCTP connection to the given host and port. On error it prints an error message prefixed with a specific fixed string that test cases can check for:
+	Short: "Attempts a TCP, UDP or SCTP connection and returns useful errors",
+	Long: `Tries to open a TCP, UDP or SCTP connection to the given host and port. On error it prints an error message prefixed with a specific fixed string that test cases can check for:
 
 * UNKNOWN - Generic/unknown (non-network) error (eg, bad arguments)
 * TIMEOUT - The connection attempt timed out
@@ -42,19 +43,25 @@ var CmdConnect = &cobra.Command{
 	Run:  main,
 }
 
-var timeout time.Duration
-var protocol string
+var (
+	timeout  time.Duration
+	protocol string
+	udpData  string
+)
 
 func init() {
 	CmdConnect.Flags().DurationVar(&timeout, "timeout", time.Duration(0), "Maximum time before returning an error")
-	CmdConnect.Flags().StringVar(&protocol, "protocol", "tcp", "The protocol to use to perform the connection, can be tcp or sctp")
+	CmdConnect.Flags().StringVar(&protocol, "protocol", "tcp", "The protocol to use to perform the connection, can be tcp, udp or sctp")
+	CmdConnect.Flags().StringVar(&udpData, "udp-data", "hostname", "The UDP payload send to the server")
 }
 
 func main(cmd *cobra.Command, args []string) {
 	dest := args[0]
 	switch protocol {
 	case "", "tcp":
 		connectTCP(dest, timeout)
+	case "udp":
+		connectUDP(dest, timeout, udpData)
 	case "sctp":
 		connectSCTP(dest, timeout)
 	default:
@@ -125,3 +132,54 @@ func connectSCTP(dest string, timeout time.Duration) {
 		os.Exit(1)
 	}
 }
+
+func connectUDP(dest string, timeout time.Duration, data string) {
+	var (
+		readBytes int
+		buf       = make([]byte, 1024)
+	)
+
+	if _, err := net.ResolveUDPAddr("udp", dest); err != nil {
+		fmt.Fprintf(os.Stderr, "DNS: %v\n", err)
+		os.Exit(1)
+	}
+
+	conn, err := net.Dial("udp", dest)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "OTHER: %v\n", err)
+		os.Exit(1)
+	}
+
+	if timeout > 0 {
+		if err = conn.SetDeadline(time.Now().Add(timeout)); err != nil {
+			fmt.Fprintf(os.Stderr, "OTHER: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	if _, err = conn.Write([]byte(fmt.Sprintf("%s\n", data))); err != nil {
+		parseUDPErrorAndExit(err)
+	}
+
+	if readBytes, err = conn.Read(buf); err != nil {
+		parseUDPErrorAndExit(err)
+	}
+
+	// ensure the response from UDP server
+	if readBytes == 0 {
+		fmt.Fprintf(os.Stderr, "OTHER: No data received from the server. Cannot guarantee the server received the request.\n")
+		os.Exit(1)
+	}
+}
+
+func parseUDPErrorAndExit(err error) {
+	neterr, ok := err.(net.Error)
+	if ok && neterr.Timeout() {
+		fmt.Fprintf(os.Stderr, "TIMEOUT: %v\n", err)
+	} else if strings.Contains(err.Error(), "connection refused") {
+		fmt.Fprintf(os.Stderr, "REFUSED: %v\n", err)
+	} else {
+		fmt.Fprintf(os.Stderr, "UNKNOWN: %v\n", err)
+	}
+	os.Exit(1)
+}