Add digest example

Add digest example that redirects a packet and sends a digest message
that contains the source mac address and the ingress port (port where
the packet arrived)

digest/Makefile

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+## call with make PROG=xxx to build
+##  make PROG=xxx clean|generate|realclean
+#
+## Argument for the CLANG compiler
+CLANG ?= clang
+P4C_PNA_P4TC ?= p4c-pna-p4tc
+PROG ?= digest
+#we need to have a headers package instead of this..
+INCLUDES= -I../include
+# Optimization flags to save space
+CFLAGS+= -O2 -g -c -D__KERNEL__ -D__ASM_SYSREG_H -DBTF \
+	 -Wno-unused-value  -Wno-pointer-sign \
+	 -Wno-compare-distinct-pointer-types \
+	 -Wno-gnu-variable-sized-type-not-at-end \
+	 -Wno-address-of-packed-member -Wno-tautological-compare \
+	 -Wno-unknown-warning-option -Wnoparentheses-equality
+
+TMPL+=generated/$(PROG).template
+TMPL+=generated/$(PROG).json
+SRCS+=generated/$(PROG)_parser.c
+SRCS+=generated/$(PROG)_control_blocks.c
+OBJS=$(SRCS:.c=.o)
+all: $(OBJS)
+
+$(OBJS): %.o : %.c
+	$(CLANG) $(CFLAGS) $(INCLUDES) --target=bpf -mcpu=probe -c $< -o $@
+
+generate:
+	$(P4C_PNA_P4TC) $(PROG).p4 -o generated/
+
+clean:
+	rm -f $(OBJS)
+
+realclean:
+	rm -f $(OBJS) $(SRCS) $(TMPL) $(PROG)_parser.h

digest/README.md

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+# digest
+
+The *digest* program first parses ethernet <u>ipv4</u> packets. Any other packets are
+rejected. After the parser recognizes an ipv4 packet, the src ip address is used as a lookup
+key for table *nh_table*. On a table hit, the programmed action *send_nh(port, srcMac, dstMac)* instance is executed.
+The action first sets the src and destination mac address, then redirects the packet to a specified port, sets the ingress_port, sets `send_digest` to true and redirects the packet. On a table miss the packet is simply dropped.
+`my_ingress_metadata_t` will hold the port on where the packet arrived and `send_digest`. `send_digest` signals to the deparser to send a digest message to user space. This digest message will hold the source mac address and the port where the packet arrived:
+
+```
+struct mac_learn_digest_t {
+    @tc_type("macaddr") bit<48> srcAddr;
+    @tc_type("dev") PortId_t ingress_port;
+};
+```
+
+## Setup Requirements
+
+Make sure that the p4node basic container has already been created at this point(as per instructions found in [p4node](https://github.com/p4tc-dev/p4tc-examples-pub.git)). To run the sample described setup here requires 4 terminals, three terminals inside the container and one on the VM side to generate traffic.
+
+### Terminal 1 (observation of tc commands on p4node).
+
+Enter the container p4node:
+
+`sudo ip netns exec p4node /bin/bash`
+
+setup path for TC binary
+
+`TC="/usr/sbin/tc"`
+
+setup the path to where the json introspection file can be found..
+
+```
+cd /home/vagrant/p4tc-examples-pub/digest/generated
+export INTROSPECTION=.
+```
+run TC monitor:
+`$TC mon p4 events`
+
+### Terminal 2 (observation of p4 digest events on p4node).
+
+First enter the container and make sure you have the introspection path setup
+
+Enter the container p4node:
+
+`sudo ip netns exec p4node /bin/bash`
+
+setup path for TC binary
+
+`TC="/usr/sbin/tc"`
+
+setup the path to where the json introspection file can be found..
+
+```
+cd /home/vagrant/p4tc-examples-pub/digest/generated
+export INTROSPECTION=.
+```
+
+run TC monitor for digest events:
+`$TC mon p4 digest`
+
+### Terminal 3 (observes incoming traffic into p4node)
+
+First enter the container and make sure you have the introspection path setup
+
+`sudo ip netns exec p4node /bin/bash`
+
+Now let's listen to traffic on port0
+
+```
+DEV=port0
+tcpdump -n -i $DEV -e
+```
+
+### Terminal 4 (to instantiate and runtime control the program)
+
+We will run commands to first load the prog and then do required runtime setup.
+
+First enter the container
+
+```
+sudo ip netns exec p4node /bin/bash
+cd /home/vagrant/p4tc-examples-pub/digest
+```
+
+```
+modprobe ext_Digest
+```
+
+Compile the parser and control blocks programs if you have not already
+
+`make`
+
+Make sure you have the introspection path setup and load the *digest* program
+
+```
+cd generated
+export INTROSPECTION=.
+TC="/usr/sbin/tc"
+./digest.template
+```
+
+now instantiate the prog
+
+```
+$TC filter add block 21 ingress protocol all prio 10 p4 pname digest \
+action bpf obj digest_parser.o section p4tc/parse \
+action bpf obj digest_control_blocks.o section p4tc/main
+```
+
+### Terminal 5 (on the VM side)
+
+Try sending a message of packets which will be dropped by the parser (observe tcpdump on terminal 3)..
+
+`ping -I p4port0 10.0.1.2 -c 1`
+
+Let's check some stats, below shows 3 packets dropped by the parser on <u>terminal 3</u>:
+
+```
+$TC -s filter ls block 21 ingress
+filter protocol all pref 10 p4 chain 0
+filter protocol all pref 10 p4 chain 0 handle 0x1 pname digest
+	action order 1: bpf digest_parser.o:[p4tc/parse] id 92 name tc_parse_func tag 1bd66321c5ad54e4 jited default-action pipe
+	index 1 ref 1 bind 1 installed 590 sec used 293 sec firstused 295 sec
+	Action statistics:
+	Sent 84 bytes 3 pkt (dropped 3, overlimits 0 requeues 0)
+	backlog 0b 0p requeues 0
+
+	action order 2: bpf digest_control_blocks.o:[p4tc/main] id 94 name tc_ingress_func tag 42e6e971daa41152 jited default-action pipe
+	 index 2 ref 1 bind 1 installed 590 sec used 590 sec
+	Action statistics:
+	Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
+	backlog 0b 0p requeues 0
+```
+
+Ok, back on <u>terminal 4</u> let's create an entry to match on the dst address *10.0.0.2* and rewrite the src mac to *00:01:02:03:04:05* and dst mac *06:07:08:09:11:12* then send out on *port1* - watch <u>terminal 1</u> for events.
+
+```
+$TC p4ctrl create digest/table/ingress/nh_table \
+dstAddr 10.0.0.2 \
+action send_nh param port port1 param srcMac 06:07:08:09:11:12 param dstMac 00:01:02:03:04:05
+```
+
+On <u>terminal 4</u> watch *port1* traffic (recall that you are watching incoming traffic on <u>terminal 2</u> on *port0*):
+
+`tcpdump -n -i port1 -e`
+
+Now you can see the rewritten mac address when you generate traffic on terminal 5 as follows:
+
+```
+cd /home/vagrant/p4tc-examples-pub/digest
+
+sudo ../../sendpacket/sendpacket.py ./testpkt.yml
+```
+
+On <u>terminal 2</u> look for the digest event
+
+## General help on runtime CLI
+
+First just dump all possible tables in this program
+
+*$TC p4ctrl create digest/table help*
+
+```
+Tables for pipeline digest:
+	  table name ingress/nh_table
+	  table id 1
+```
+
+As we can see, there is only one with a path ingress/nh_table
+
+Now let's get help on the *create* command for this table:
+
+*$TC p4ctrl create digest/table/ingress/nh_table help*
+
+```
+Key fields for table nh_table:
+	 key name dstAddr
+	 key id 1
+	 key type ipv4
+	 key match type 	 exact
+
+Actions for table nh_table:
+	  act name ingress/send_nh
+	  act id 1
+
+	  Params for ingress/send_nh:
+	    param name port
+	    param id 1
+	    param type dev
+
+	    param name srcMac
+	    param id 2
+	    param type macaddr
+
+	    param name dstMac
+	    param id 3
+	    param type macaddr
+
+          act name ingress/drop
+          act id 2
+```
+
+Above is indicating the table has a key called dstAddr which is of type ipv4 address and that it takes one action:
+  - *send_nh* which takes 3 params 1)*port*, a linux netdev 2) *srcMac*, a mac address 3) *dstMac*, also a mac address
+
+And help on the *delete* command:
+
+*$TC p4ctrl delete digest/table/ingress/nh_table help*
+
+```
+Key fields for table nh_table:
+	 key name dstAddr
+	 key id 1
+	 key type ipv4
+	 key match type  exact
+```
+
+This shows the key name "dstAddr" as an exact IPv4 address.
+Example to delete the entry we created:
+
+*$TC p4ctrl delete digest/table/ingress/nh_table dstAddr 10.0.0.2*
+
+And to delete/flush the whole table:
+
+*$TC p4ctrl delete digest/table/ingress/nh_table
+
+And help on the *get* command:
+
+*$TC p4ctrl get digest/table/ingress/nh_table help*
+
+```
+Key fields for table nh_table:
+	 key name dstAddr
+	 key id 1
+	 key type ipv4
+	 key match type 	 exact
+```
+
+This shows the key name "dstAddr" as an exact IPv4 address.
+For example to retrieve the entry we created using our key of 10.0.0.2:
+
+*$TC p4ctrl get digest/table/ingress/nh_table dstAddr 10.0.0.2*
+
+Note, we can dump the whole table as such:
+
+*$TC p4ctrl get digest/table/ingress/nh_table*
+
+
+To cleanup
+----------
+To clean up you need to run the following script on Terminal 4, where the template was installed and the program was instantiated:
+
+`./digest.purge`

digest/digest.p4

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+/* -*- P4_16 -*- */
+
+#include <core.p4>
+#include <tc/pna.p4>
+#include "digest_metadata.p4"
+#include "digest_parser.p4"
+
+#define L3_TABLE_SIZE 2048
+
+struct mac_learn_digest_t {
+    @tc_type("macaddr") bit<48> srcAddr;
+    @tc_type("dev") PortId_t ingress_port;
+};
+
+/***************** M A T C H - A C T I O N  *********************/
+
+control ingress(
+    inout my_ingress_headers_t  hdr,
+    inout my_ingress_metadata_t meta,
+    in    pna_main_input_metadata_t  istd,
+    inout pna_main_output_metadata_t ostd
+)
+{
+   action send_nh(@tc_type("dev") PortId_t port, @tc_type("macaddr") bit<48> srcMac, @tc_type("macaddr") bit<48> dstMac) {
+        hdr.ethernet.srcAddr = srcMac;
+        hdr.ethernet.dstAddr = dstMac;
+        meta.ingress_port = istd.input_port;
+        meta.send_digest = true;
+        send_to_port(port);
+   }
+
+   action drop() {
+        drop_packet();
+   }
+
+    table nh_table {
+        key = {
+            hdr.ipv4.dstAddr : exact @tc_type("ipv4") @name("dstAddr");
+        }
+        actions = {
+            send_nh;
+            drop;
+        }
+        size = L3_TABLE_SIZE;
+        const default_action = drop;
+    }
+
+    apply {
+        if (hdr.ipv4.isValid()) {
+            nh_table.apply();
+        }
+    }
+}
+
+    /*********************  D E P A R S E R  ************************/
+
+control Ingress_Deparser(
+    packet_out pkt,
+    inout    my_ingress_headers_t hdr,
+    in    my_ingress_metadata_t meta,
+    in    pna_main_output_metadata_t ostd)
+{
+   Digest<mac_learn_digest_t>() digest_inst;
+
+   apply {
+       pkt.emit(hdr.ethernet);
+       pkt.emit(hdr.ipv4);
+       if (meta.send_digest) {
+           mac_learn_digest_t mac_learn_digest;
+           mac_learn_digest.srcAddr = hdr.ethernet.srcAddr;
+           mac_learn_digest.ingress_port = meta.ingress_port;
+           digest_inst.pack(mac_learn_digest);
+       }
+   }
+}
+
+/************ F I N A L   P A C K A G E ******************************/
+
+PNA_NIC(
+    Ingress_Parser(),
+    ingress(),
+    Ingress_Deparser()
+) main;

digest/digest_metadata.p4

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+/* -*- P4_16 -*- */
+
+    /******  G L O B A L   I N G R E S S   M E T A D A T A  *********/
+
+struct my_ingress_metadata_t {
+    @tc_type("dev") PortId_t ingress_port;
+    bool send_digest;
+}