1..  SPDX-License-Identifier: BSD-3-Clause
2    Copyright 2017 Mellanox Technologies, Ltd
3
4Basic RTE Flow Filtering Sample Application
5===========================================
6
7The Basic RTE flow filtering sample application is a simple example of a
8creating a RTE flow rule.
9
10It is intended as a demonstration of the basic components RTE flow rules.
11
12
13Compiling the Application
14-------------------------
15
16To compile the sample application see :doc:`compiling`.
17
18
19Running the Application
20-----------------------
21
22To run the example in a ``linux`` environment:
23
24.. code-block:: console
25
26    ./<build_dir>/examples/dpdk-flow_filtering -l 1 -n 1
27
28Refer to *DPDK Getting Started Guide* for general information on running
29applications and the Environment Abstraction Layer (EAL) options.
30
31
32Explanation
33-----------
34
35The example is built from 2 files,
36``main.c`` which holds the example logic and ``flow_blocks.c`` that holds the
37implementation for building the flow rule.
38
39The following sections provide an explanation of the main components of the
40code.
41
42All DPDK library functions used in the sample code are prefixed with ``rte_``
43and are explained in detail in the *DPDK API Documentation*.
44
45
46The Main Function
47~~~~~~~~~~~~~~~~~
48
49The ``main()`` function located in ``main.c`` file performs the initialization
50and runs the main loop function.
51
52The first task is to initialize the Environment Abstraction Layer (EAL).  The
53``argc`` and ``argv`` arguments are provided to the ``rte_eal_init()``
54function. The value returned is the number of parsed arguments:
55
56.. literalinclude:: ../../../examples/flow_filtering/main.c
57    :language: c
58    :start-after: Initialize EAL. 8<
59    :end-before: >8 End of Initialization of EAL.
60    :dedent: 1
61
62
63The ``main()`` also allocates a mempool to hold the mbufs (Message Buffers)
64used by the application:
65
66.. literalinclude:: ../../../examples/flow_filtering/main.c
67    :language: c
68    :start-after: Allocates a mempool to hold the mbufs. 8<
69    :end-before: >8 End of allocating a mempool to hold the mbufs.
70    :dedent: 1
71
72Mbufs are the packet buffer structure used by DPDK. They are explained in
73detail in the "Mbuf Library" section of the *DPDK Programmer's Guide*.
74
75The ``main()`` function also initializes all the ports using the user defined
76``init_port()`` function which is explained in the next section:
77
78.. literalinclude:: ../../../examples/flow_filtering/main.c
79    :language: c
80    :start-after: Initializes all the ports using the user defined init_port(). 8<
81    :end-before: >8 End of Initializing the ports using user defined init_port().
82    :dedent: 1
83
84Once the initialization is complete, we set the flow rule using the
85following code:
86
87.. literalinclude:: ../../../examples/flow_filtering/main.c
88    :language: c
89    :start-after: Create flow for send packet with. 8<
90    :end-before: >8 End of creating flow for send packet with.
91    :dedent: 1
92
93In the last part the application is ready to launch the
94``main_loop()`` function. Which is explained below.
95
96
97.. literalinclude:: ../../../examples/flow_filtering/main.c
98    :language: c
99    :start-after: Launching main_loop(). 8<
100    :end-before: >8 End of launching main_loop().
101    :dedent: 1
102
103The Port Initialization  Function
104~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
105
106The main functional part of the port initialization used in the flow filtering
107application is shown below:
108
109.. literalinclude:: ../../../examples/flow_filtering/main.c
110    :language: c
111    :start-after: Port initialization used in flow filtering. 8<
112    :end-before: >8 End of Port initialization used in flow filtering.
113
114The Ethernet port is configured with default settings using the
115``rte_eth_dev_configure()`` function and the ``port_conf_default`` struct:
116
117.. literalinclude:: ../../../examples/flow_filtering/main.c
118    :language: c
119    :start-after: Ethernet port configured with default settings. 8<
120    :end-before: >8 End of ethernet port configured with default settings.
121    :dedent: 1
122
123For this example we are configuring number of rx and tx queues that are connected
124to a single port.
125
126.. literalinclude:: ../../../examples/flow_filtering/main.c
127    :language: c
128    :start-after: Configuring number of RX and TX queues connected to single port. 8<
129    :end-before: >8 End of Configuring RX and TX queues connected to single port.
130    :dedent: 1
131
132In the next step we create and apply the flow rule. which is to send packets
133with destination ip equals to 192.168.1.1 to queue number 1. The detail
134explanation of the ``generate_ipv4_flow()`` appears later in this document:
135
136.. literalinclude:: ../../../examples/flow_filtering/main.c
137    :language: c
138    :start-after: Create flow for send packet with. 8<
139    :end-before: >8 End of create flow and the flow rule.
140    :dedent: 1
141
142We are setting the RX port to promiscuous mode:
143
144.. literalinclude:: ../../../examples/flow_filtering/main.c
145    :language: c
146    :start-after: Setting the RX port to promiscuous mode. 8<
147    :end-before: >8 End of setting the RX port to promiscuous mode.
148    :dedent: 1
149
150The last step is to start the port.
151
152.. literalinclude:: ../../../examples/flow_filtering/main.c
153    :language: c
154    :start-after: Starting the port. 8<
155    :end-before: >8 End of starting the port.
156    :dedent: 1
157
158
159The main_loop function
160~~~~~~~~~~~~~~~~~~~~~~
161
162As we saw above the ``main()`` function calls an application function to handle
163the main loop. For the flow filtering application the main_loop function
164looks like the following:
165
166.. literalinclude:: ../../../examples/flow_filtering/main.c
167    :language: c
168    :start-after: Main_loop for flow filtering. 8<
169    :end-before: >8 End of reading the packets from all queues.
170
171The main work of the application is reading the packets from all
172queues and printing for each packet the destination queue:
173
174.. literalinclude:: ../../../examples/flow_filtering/main.c
175    :language: c
176    :start-after: Reading the packets from all queues. 8<
177    :end-before: >8 End of main_loop for flow filtering.
178
179
180The forwarding loop can be interrupted and the application closed using
181``Ctrl-C``. Which results in closing the port and the device using
182``rte_eth_dev_stop`` and ``rte_eth_dev_close``
183
184The generate_ipv4_flow function
185~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
186
187The generate_ipv4_flow function is responsible for creating the flow rule.
188This function is located in the ``flow_blocks.c`` file.
189
190.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
191    :language: c
192    :start-after: Function responsible for creating the flow rule. 8<
193    :end-before: >8 End of function responsible for creating the flow rule.
194
195The first part of the function is declaring the structures that will be used.
196
197.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
198    :language: c
199    :start-after: Declaring structs being used. 8<
200    :end-before: >8 End of declaring structs being used.
201    :dedent: 1
202
203The following part create the flow attributes, in our case ingress.
204
205.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
206    :language: c
207    :start-after: Set the rule attribute, only ingress packets will be checked. 8<
208    :end-before: >8 End of setting the rule attribute.
209    :dedent: 1
210
211The third part defines the action to be taken when a packet matches
212the rule. In this case send the packet to queue.
213
214.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
215    :language: c
216    :start-after: Function responsible for creating the flow rule. 8<
217    :end-before: >8 End of setting the rule attribute.
218
219The fourth part is responsible for creating the pattern and is built from
220number of steps. In each step we build one level of the pattern starting with
221the lowest one.
222
223Setting the first level of the pattern ETH:
224
225.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
226    :language: c
227    :start-after: Set this level to allow all. 8<
228    :end-before: >8 End of setting the first level of the pattern.
229    :dedent: 1
230
231Setting the second level of the pattern IP:
232
233.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
234    :language: c
235    :start-after: Setting the second level of the pattern. 8<
236    :end-before: >8 End of setting the second level of the pattern.
237    :dedent: 1
238
239Closing the pattern part.
240
241.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
242    :language: c
243    :start-after: The final level must be always type end. 8<
244    :end-before: >8 End of final level must be always type end.
245    :dedent: 1
246
247The last part of the function is to validate the rule and create it.
248
249.. literalinclude:: ../../../examples/flow_filtering/flow_blocks.c
250    :language: c
251    :start-after: Validate the rule and create it. 8<
252    :end-before: >8 End of validation the rule and create it.
253    :dedent: 1
254