add netem limit

docs/pages/introduction/feature.txt

@@ -19,6 +19,7 @@ The following parameters can be set to network interfaces:
 - Packet corruption rate ``[%]``
 - Packet duplicate rate ``[%]``
 - Packet reordering rate  ``[%]``
+- Packet limit count  ``[COUNT]``
 
 Targets
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

docs/pages/usage/tcset/tcset_help_output.txt

@@ -1,7 +1,7 @@
 ::
 
     usage: tcset [-h] [-V] [--tc-command | --tc-script] [--debug | --quiet] [--debug-query] [--stacktrace] [--import-setting] [--overwrite | --change | --add] [--rate BANDWIDTH_RATE] [--delay LATENCY_TIME] [--delay-distro LATENCY_DISTRO_TIME] [--delay-distribution {normal,pareto,paretonormal}] [--loss PACKET_LOSS_RATE] [--duplicate PACKET_DUPLICATE_RATE]
-                 [--corrupt CORRUPTION_RATE] [--reordering REORDERING_RATE] [--shaping-algo {htb,tbf}] [--iptables] [--direction {outgoing,incoming}] [--network DST_NETWORK] [--src-network SRC_NETWORK] [--port DST_PORT] [--src-port SRC_PORT] [--ipv6] [--exclude-dst-network EXCLUDE_DST_NETWORK] [--exclude-src-network EXCLUDE_SRC_NETWORK]
+                 [--corrupt CORRUPTION_RATE] [--reordering REORDERING_RATE] [--limit PACKET_LIMIT_COUNT] [--shaping-algo {htb,tbf}] [--iptables] [--direction {outgoing,incoming}] [--network DST_NETWORK] [--src-network SRC_NETWORK] [--port DST_PORT] [--src-port SRC_PORT] [--ipv6] [--exclude-dst-network EXCLUDE_DST_NETWORK] [--exclude-src-network EXCLUDE_SRC_NETWORK]
                  [--exclude-dst-port EXCLUDE_DST_PORT] [--exclude-src-port EXCLUDE_SRC_PORT] [--docker] [--src-container SRC_CONTAINER] [--dst-container DST_CONTAINER]
                  device
 
@@ -42,6 +42,8 @@
                             packet corruption rate [%]. the valid range is from 0 to 100. packet corruption means a single-bit error at a random offset in the packet. (default=0)
       --reordering REORDERING_RATE
                             packet reordering rate [%]. the valid range is from 0 to 100. (default=0)
+      --limit PACKET_LIMIT_COUNT
+                            limits the maximum number of packets the qdisc may hold when doing delay. the minimum value is 1. (default=0)
       --shaping-algo {htb,tbf}
                             shaping algorithm. defaults to htb (recommended).
       --iptables            use iptables for traffic control.

tcconfig/_netem_param.py

@@ -51,6 +51,7 @@ def __init__(
         packet_duplicate_rate=None,
         corruption_rate=None,
         reordering_rate=None,
+        packet_limit_count=None,
     ):
         self.__device = device
 
@@ -59,6 +60,7 @@ def __init__(
         self.__packet_duplicate_rate = convert_rate_to_f(packet_duplicate_rate)  # [%]
         self.__corruption_rate = convert_rate_to_f(corruption_rate)  # [%]
         self.__reordering_rate = convert_rate_to_f(reordering_rate)  # [%]
+        self.__packet_limit_count = convert_rate_to_f(packet_limit_count)  # [COUNT]
 
         self.__latency_time = None
         if latency_time:
@@ -106,12 +108,14 @@ def validate_netem_parameter(self):
         self.__validate_corruption_rate()
         self.__validate_reordering_rate()
         self.__validate_reordering_and_delay()
+        self.__validate_packet_limit_count()
 
         netem_param_values = [
             self.__packet_loss_rate,
             self.__packet_duplicate_rate,
             self.__corruption_rate,
             self.__reordering_rate,
+            self.__packet_limit_count,
         ]
         if self.__bandwidth_rate:
             netem_param_values.append(self.__bandwidth_rate.kilo_bps)
@@ -128,7 +132,7 @@ def validate_netem_parameter(self):
             raise hr.ParameterError(
                 "there are no valid net emulation parameters found. "
                 "at least one or more following parameters are required: "
-                "--rate, --delay, --loss, --duplicate, --corrupt, --reordering"
+                "--rate, --delay, --loss, --duplicate, --corrupt, --reordering, --limit"
             )
 
     def validate_bandwidth_rate(self):
@@ -175,6 +179,8 @@ def make_param_name(self):
         if self.__reordering_rate:
             item_list.append(f"reordering{self.__reordering_rate}")
 
+        if self.__packet_limit_count:
+            item_list.append(f"limit{self.__packet_limit_count}")
         return "_".join(item_list)
 
     def make_netem_command_parts(self):
@@ -205,6 +211,8 @@ def make_netem_command_parts(self):
         if self.__reordering_rate > 0:
             item_list.append(f"reorder {self.__reordering_rate:f}%")
 
+        if self.__packet_limit_count > 0:
+            item_list.append(f"limit {self.__packet_limit_count:f}")
         return " ".join(item_list)
 
     def calc_hash(self, extra=""):
@@ -274,3 +282,7 @@ def __validate_reordering_rate(self):
     def __validate_reordering_and_delay(self):
         if self.__reordering_rate and self.__latency_time and self.__latency_time.milliseconds <= 0:
             raise hr.ParameterError("reordering needs latency to be specified: set latency > 0")
+
+    def __validate_packet_limit_count(self):
+        if self.__packet_limit_count and self.__packet_limit_count <= 0:
+            raise hr.ParameterError("packets limit count can't be less than 1: set limit > 0")

tcconfig/parser/_model.py

@@ -30,3 +30,4 @@ class Qdisc(Model):
     corrupt = Text()
     reorder = Text()
     rate = Text()
+    limit = Integer()

tcconfig/parser/_qdisc.py

@@ -59,6 +59,7 @@ def parse(self, device, text):
             self.__parse_netem_param(line, "duplicate", pp.nums + ".%")
             self.__parse_netem_param(line, "corrupt", pp.nums + ".%")
             self.__parse_netem_param(line, "reorder", pp.nums + ".%")
+            self.__parse_netem_param(line, "limit", pp.nums)
             self.__parse_bandwidth_rate(line)
 
             logger.debug(f"parse a qdisc entry: {self.__parsed_param}")

tcconfig/tcset.py

@@ -171,6 +171,14 @@ def get_arg_parser():
         to {:d}. (default=%(default)s)
         """.format(MIN_REORDERING_RATE, MAX_REORDERING_RATE),
     )
+    group.add_argument(
+        "--limit",
+        dest="packet_limit_count",
+        default=0,
+        help="""limits the maximum number of packets the qdisc may hold when doing delay.
+        the minimum value is {:d}. (default=%(default)s)
+        """.format(1),
+    )
     group.add_argument(
         "--shaping-algo",
         dest="shaping_algorithm",
@@ -309,6 +317,7 @@ def __create_tc(self, device):
                 packet_duplicate_rate=options.packet_duplicate_rate,
                 corruption_rate=options.corruption_rate,
                 reordering_rate=options.reordering_rate,
+                packet_limit_count=options.packet_limit_count,
             ),
             dst_network=self._extract_dst_network(),
             exclude_dst_network=options.exclude_dst_network,

tcconfig/tcshow.py

@@ -47,6 +47,7 @@ class ShapingRuleModel(Model):
     corrupt = Text()
     reorder = Text()
     rate = Text()
+    limit = Text()
 
 
 def parse_option():

test/common.py

@@ -28,8 +28,8 @@ def print_test_result(expected, actual, error=None):
         print(error, file=sys.stderr)
 
 
-def is_invalid_param(rate, delay, packet_loss, packet_duplicate, corrupt, reordering):
-    param_values = [packet_loss, packet_duplicate, corrupt, reordering]
+def is_invalid_param(rate, delay, packet_loss, packet_duplicate, corrupt, reordering, packet_limit):
+    param_values = [packet_loss, packet_duplicate, corrupt, reordering, packet_limit]
 
     print(f"rate={rate}, params={param_values}")
 

test/parser/test_shaping_rule.py

@@ -34,6 +34,7 @@ def test_normal(self, device_value):
                 packet_duplicate_rate=0,
                 corruption_rate=0,
                 reordering_rate=0,
+                packet_limit_count=0,
             ),
             src_network="192.168.3.188",
             dst_port=5201,
@@ -51,6 +52,7 @@ def test_normal(self, device_value):
                 packet_duplicate_rate=0,
                 corruption_rate=0,
                 reordering_rate=0,
+                packet_limit_count=0,
             ),
             dst_network="192.168.3.188",
         )

test/test_parser.py

@@ -501,6 +501,7 @@ class Test_TcQdiscParser_parse:
                             Tc.Param.HANDLE: "2007:",
                             Tc.Param.PARENT: "1f87:2",
                             "direct_qlen": 1000,
+                            "limit": 1000,
                         }
                     )
                 ],
@@ -518,6 +519,7 @@ class Test_TcQdiscParser_parse:
                             Tc.Param.HANDLE: "1a9a:",
                             Tc.Param.PARENT: "1a1a:2",
                             "direct_qlen": 1000,
+                            "limit": 1000,
                         }
                     )
                 ],
@@ -538,6 +540,7 @@ class Test_TcQdiscParser_parse:
                             Tc.Param.HANDLE: "2007:",
                             Tc.Param.PARENT: "1f87:2",
                             "direct_qlen": 1000,
+                            "limit": 1000,
                         }
                     ),
                     Qdisc(
@@ -548,6 +551,7 @@ class Test_TcQdiscParser_parse:
                             "delay-distro": "1.0ms",
                             Tc.Param.HANDLE: "2008:",
                             Tc.Param.PARENT: "1f87:3",
+                            "limit": 1000,
                         }
                     ),
                 ],
@@ -568,6 +572,7 @@ class Test_TcQdiscParser_parse:
                             Tc.Param.HANDLE: "2007:",
                             Tc.Param.PARENT: "1f87:2",
                             "direct_qlen": 1000,
+                            "limit": 1000,
                         }
                     ),
                     Qdisc(
@@ -578,6 +583,7 @@ class Test_TcQdiscParser_parse:
                             "delay-distro": "1.0ms",
                             Tc.Param.HANDLE: "2008:",
                             Tc.Param.PARENT: "1f87:3",
+                            "limit": 1000,
                         }
                     ),
                 ],

test/test_traffic_control.py

@@ -229,7 +229,7 @@ def test_normal(
             shaping_algorithm=shaping_algorithm,
         )
 
-        if is_invalid_param(rate, delay, loss, duplicate, corrupt, reordering=None):
+        if is_invalid_param(rate, delay, loss, duplicate, corrupt, reordering=None, limit=None):
             with pytest.raises(ParameterError):
                 tc_obj.validate()
         else: