ISAKMP: Fix printing Delete payload SPI when size is zero

Print Security Parameter Index(es) only if the SPI Size is non zero.

Author: fxlb

print-isakmp.c

@@ -1884,14 +1884,16 @@ ikev1_d_print(netdissect_options *ndo, u_char tpay _U_,
 	ND_PRINT(" spilen=%u", spi_size);
 	num_spi = GET_BE_U_2(p->num_spi);
 	ND_PRINT(" nspi=%u", num_spi);
-	ND_PRINT(" spi=");
 	q = (const uint8_t *)(p + 1);
-	for (i = 0; i < num_spi; i++) {
-		if (i != 0)
-			ND_PRINT(",");
-		if (!rawprint(ndo, (const uint8_t *)q, spi_size))
-			goto trunc;
-		q += spi_size;
+	if (spi_size) {
+		ND_PRINT(" spi=");
+		for (i = 0; i < num_spi; i++) {
+			if (i != 0)
+				ND_PRINT(",");
+			if (!rawprint(ndo, (const uint8_t *)q, spi_size))
+				goto trunc;
+			q += spi_size;
+		}
 	}
 	return q;
 trunc: