Created new subdirectory for Fall developer day. (#60)

P4D2_2017_Fall/exercises/source_routing/README.md

@@ -0,0 +1,147 @@
+# Implementing Source Routing
+
+## Introduction
+
+The objective of this exercise is to implement source routing.  With
+source routing, the source host guides each switch in the network to
+send the packet to a specific port. The host puts a stack of output
+ports in the packet. In this example, we just put the stack after
+Ethernet header and select a special etherType to indicate that.  Each
+switch pops an item from the stack and forwards the packet according
+to the specified port number.
+
+Your switch must parse the source routing stack. Each item has a bos
+(bottom of stack) bit and a port number. The bos bit is 1 only for the
+last entry of stack.  Then at ingress, it should pop an entry from the
+stack and set the egress port accordingly.  Note that the last hop can
+also revert back the etherType to `TYPE_IPV4`.
+
+> **Spoiler alert:** There is a reference solution in the `solution`
+> sub-directory. Feel free to compare your implementation to the
+> reference.
+
+## Step 1: Run the (incomplete) starter code
+
+The directory with this README also contains a skeleton P4 program,
+`source_routing.p4`, which initially drops all packets. Your job (in
+the next step) will be to extend it to properly to route packets.
+
+Before that, let's compile the incomplete `source_routing.p4` and
+bring up a network in Mininet to test its behavior.
+
+1. In your shell, run:
+   ```bash
+   ./run.sh
+   ```
+   This will:
+   * compile `source_routing.p4`, and
+   * start a Mininet instance with three switches (`s1`, `s2`, `s3`) configured
+     in a triangle, each connected to one host (`h1`, `h2`, `h3`).
+     Check the network topology using the `net` command in mininet.
+     You can also change the topology in p4app.json
+   * The hosts are assigned IPs of `10.0.1.1`, `10.0.2.2`, etc
+     (`10.0.<Switchid>.<hostID>`).
+
+2. You should now see a Mininet command prompt. Open two terminals for
+   `h1` and `h2`, respectively:
+   ```bash
+   mininet> xterm h1 h2
+   ```
+3. Each host includes a small Python-based messaging client and
+   server. In `h2`'s xterm, start the server:
+   ```bash
+   ./receive.py
+   ```
+4. In `h1`'s xterm, send a message from the client:
+   ```bash
+   ./send.py 10.0.2.2
+   ```
+
+5. Type a list of port numbers. say `2 3 2 2 1`.  This should send the
+   packet through `h1`, `s1`, `s2`, `s3`, `s1`, `s2`, and
+   `h2`. However, `h2` will not receive the message.
+   
+6. Type `q` to exit send.py and type `exit` to leave each xterm and
+   the Mininet command line.
+
+The message was not received because each switch is programmed with
+`source_routing.p4`, which drops all packets on arrival.  You can
+verify this by looking at `build/logs/s1.log`.  Your job is to extend
+the P4 code so packets are delivered to their destination.
+
+## Step 2: Implement source routing
+
+The `source_routing.p4` file contains a skeleton P4 program with key
+pieces of logic replaced by `TODO` comments.  These should guide your
+implementation---replace each `TODO` with logic implementing the
+missing piece.
+
+A complete `source_routing.p4` will contain the following components:
+
+1. Header type definitions for Ethernet (`ethernet_t`) and IPv4
+   (`ipv4_t`) and Source Route (`srcRoute_t`).
+2. **TODO:** Parsers for Ethernet and Source Route that populate
+   `ethernet` and `srcRoutes` fields.
+3. An action to drop a packet, using `mark_to_drop()`.
+4. **TODO:** An action (called `srcRoute_nhop`), which will:
+	1. Set the egress port for the next hop. 
+	2. remove the first entry of srcRoutes
+5. A control with an `apply` block that:
+    1. checks the existance of source routes.
+    2. **TODO:** if statement to change etherent.etherType if it is the last hop
+    3. **TODO:** call srcRoute_nhop action
+6. A deparser that selects the order in which fields inserted into the outgoing
+   packet.
+7. A `package` instantiation supplied with the parser, control, and deparser.
+    > In general, a package also requires instances of checksum verification
+    > and recomputation controls.  These are not necessary for this tutorial
+    > and are replaced with instantiations of empty controls.
+
+## Step 3: Run your solution
+
+Follow the instructions from Step 1. This time, your message from `h1`
+should be delivered to `h2`.
+
+Check the `ttl` of the IP header. Each hop decrements `ttl`.  The port
+sequence `2 3 2 2 1`, forces the packet to have a loop, so the `ttl`
+should be 59 at `h2`.  Can you find the port sequence for the shortest
+path?
+
+### Food for thought
+* Can we change the program to handle both IPv4 forwarding and source
+routing at the same time?
+* How would you enhance your program to let the first switch add the
+path, so that source routing would be transparent to end-hosts?
+
+### Troubleshooting
+
+There are several ways that problems might manifest:
+
+1. `source_routing.p4` fails to compile. In this case, `run.sh` will
+   report the error emitted from the compiler and stop.
+2. `source_routing.p4` compiles but switches or mininet do not start.
+   Do you have another instance of mininet running? Did the previous
+   run of mininet crash?  if yes, check "Cleaning up Mininet" bellow.
+3. `source_routing.p4` compiles but the switch does not process
+   packets in the desired way. The `build/logs/<switch-name>.log`
+   files contain trace messages describing how each switch processes
+   each packet. The output is detailed and can help pinpoint logic
+   errors in your implementation.  The
+   `build/<switch-name>-<interface-name>.pcap` also contains the pcap
+   of packets on each interface. Use `tcpdump -r <filename> -xxx` to
+   print the hexdump of the packets.
+
+#### Cleaning up Mininet
+
+In the cases above, `run.sh` may leave a Mininet instance running in
+the background.  Use the following command to clean up these
+instances:
+
+```bash
+mn -c
+```
+
+## Next Steps
+
+Congratulations, your implementation works!  Move on to
+[Calculator](../calc).

P4D2_2017_Fall/exercises/source_routing/p4app.json

@@ -0,0 +1,30 @@
+{
+    "program": "source_routing.p4",
+    "language": "p4-16",
+    "targets": {
+      "multiswitch": {
+          "auto-control-plane": true,
+          "cli": true,
+          "pcap_dump": true,
+          "bmv2_log": true,
+          "links": [["h1", "s1"], ["s1", "s2"], ["s1", "s3"], ["s3", "s2"], ["s2", "h2"], ["s3", "h3"]],
+          "hosts": {
+            "h1": {
+            },
+            "h2": {
+            },
+            "h3": {
+            }
+
+          },
+          "switches": {
+              "s1": {
+              },
+              "s2": {
+              },
+              "s3": {
+              }
+          }
+	    }
+    }
+}

P4D2_2017_Fall/exercises/source_routing/receive.py

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+#!/usr/bin/env python
+import sys
+import struct
+
+from scapy.all import sniff, sendp, hexdump, get_if_list, get_if_hwaddr, bind_layers
+from scapy.all import Packet, IPOption
+from scapy.all import IP, UDP, Raw, Ether
+from scapy.layers.inet import _IPOption_HDR
+from scapy.fields import *
+
+def get_if():
+    ifs=get_if_list()
+    iface=None
+    for i in get_if_list():
+        if "eth0" in i:
+            iface=i
+            break;
+    if not iface:
+        print "Cannot find eth0 interface"
+        exit(1)
+    return iface
+
+class IPOption_MRI(IPOption):
+    name = "MRI"
+    option = 31
+    fields_desc = [ _IPOption_HDR,
+                    FieldLenField("length", None, fmt="B",
+                                  length_of="swids",
+                                  adjust=lambda pkt,l:l+4),
+                    ShortField("count", 0),
+                    FieldListField("swids",
+                                   [],
+                                   IntField("", 0),
+                                   length_from=lambda pkt:pkt.count*4) ]
+def handle_pkt(pkt):
+    print "got a packet"
+    pkt.show2()
+#    hexdump(pkt)
+    sys.stdout.flush()
+
+class SourceRoute(Packet):
+   fields_desc = [ BitField("bos", 0, 1),
+                   BitField("port", 0, 15)]
+class SourceRoutingTail(Packet):
+   fields_desc = [ XShortField("etherType", 0x800)]
+
+bind_layers(Ether, SourceRoute, type=0x1234)
+bind_layers(SourceRoute, SourceRoute, bos=0)
+bind_layers(SourceRoute, SourceRoutingTail, bos=1)
+
+def main():
+    iface = 'h2-eth0'
+    print "sniffing on %s" % iface
+    sys.stdout.flush()
+    sniff(filter="udp and port 4321", iface = iface,
+          prn = lambda x: handle_pkt(x))
+
+if __name__ == '__main__':
+    main()

P4D2_2017_Fall/exercises/source_routing/run.sh

@@ -0,0 +1,5 @@
+P4APPRUNNER=../../utils/p4apprunner.py
+mkdir -p build
+tar -czf build/p4app.tgz * --exclude='build'
+#cd build
+sudo python $P4APPRUNNER p4app.tgz --build-dir ./build

P4D2_2017_Fall/exercises/source_routing/send.py

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+#!/usr/bin/env python
+import argparse
+import sys
+import socket
+import random
+import struct
+
+from scapy.all import sendp, send, get_if_list, get_if_hwaddr, bind_layers
+from scapy.all import Packet
+from scapy.all import Ether, IP, UDP
+from scapy.fields import *
+import readline
+
+def get_if():
+    ifs=get_if_list()
+    iface=None # "h1-eth0"
+    for i in get_if_list():
+        if "eth0" in i:
+            iface=i
+            break;
+    if not iface:
+        print "Cannot find eth0 interface"
+        exit(1)
+    return iface
+
+class SourceRoute(Packet):
+   fields_desc = [ BitField("bos", 0, 1),
+                   BitField("port", 0, 15)]
+
+bind_layers(Ether, SourceRoute, type=0x1234)
+bind_layers(SourceRoute, SourceRoute, bos=0)
+bind_layers(SourceRoute, IP, bos=1)
+
+def main():
+
+    if len(sys.argv)<2:
+        print 'pass 2 arguments: <destination>'
+        exit(1)
+
+    addr = socket.gethostbyname(sys.argv[1])
+    iface = get_if()
+    print "sending on interface %s to %s" % (iface, str(addr))
+
+    while True:
+        print
+        s = str(raw_input('Type space separated port nums '
+                          '(example: "2 3 2 2 1") or "q" to quit: '))
+        if s == "q":
+            break;
+        print
+
+        i = 0
+        pkt =  Ether(src=get_if_hwaddr(iface), dst='ff:ff:ff:ff:ff:ff');
+        for p in s.split(" "):
+            try:
+                pkt = pkt / SourceRoute(bos=0, port=int(p))
+                i = i+1
+            except ValueError:
+                pass
+        if pkt.haslayer(SourceRoute):
+            pkt.getlayer(SourceRoute, i).bos = 1
+
+        pkt = pkt / IP(dst=addr) / UDP(dport=4321, sport=1234)
+        pkt.show2()
+        sendp(pkt, iface=iface, verbose=False)
+
+    #pkt = pkt / SourceRoute(bos=0, port=2) / SourceRoute(bos=0, port=3);
+    #pkt = pkt / SourceRoute(bos=0, port=2) / SourceRoute(bos=0, port=2);
+    #pkt = pkt / SourceRoute(bos=1, port=1)
+
+
+if __name__ == '__main__':
+    main()

P4D2_2017_Fall/exercises/source_routing/solution/source_routing.p4

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+/* -*- P4_16 -*- */
+#include <core.p4>
+#include <v1model.p4>
+
+const bit<16> TYPE_IPV4 = 0x800;
+const bit<16> TYPE_SRCROUTING = 0x1234;
+
+#define MAX_HOPS 9
+
+/*************************************************************************
+*********************** H E A D E R S  ***********************************
+*************************************************************************/
+
+typedef bit<9>  egressSpec_t;
+typedef bit<48> macAddr_t;
+typedef bit<32> ip4Addr_t;
+
+header ethernet_t {
+    macAddr_t dstAddr;
+    macAddr_t srcAddr;
+    bit<16>   etherType;
+}
+
+header srcRoute_t {
+    bit<1>    bos;
+    bit<15>   port;
+}
+
+header ipv4_t {
+    bit<4>    version;
+    bit<4>    ihl;
+    bit<8>    diffserv;
+    bit<16>   totalLen;
+    bit<16>   identification;
+    bit<3>    flags;
+    bit<13>   fragOffset;
+    bit<8>    ttl;
+    bit<8>    protocol;
+    bit<16>   hdrChecksum;
+    ip4Addr_t srcAddr;
+    ip4Addr_t dstAddr;
+}
+
+struct metadata {
+    /* empty */
+}
+
+struct headers {
+    ethernet_t              ethernet;
+    srcRoute_t[MAX_HOPS]    srcRoutes;
+    ipv4_t                  ipv4;
+}
+
+/*************************************************************************
+*********************** P A R S E R  ***********************************
+*************************************************************************/
+
+parser MyParser(packet_in packet,
+                out headers hdr,
+                inout metadata meta,
+                inout standard_metadata_t standard_metadata) {
+    
+    state start {
+        transition parse_ethernet;
+    }
+
+    state parse_ethernet {
+        packet.extract(hdr.ethernet);
+        transition select(hdr.ethernet.etherType) {
+            TYPE_SRCROUTING: parse_srcRouting;
+            default: accept;
+        }
+    }
+
+    state parse_srcRouting {
+        packet.extract(hdr.srcRoutes.next);
+        transition select(hdr.srcRoutes.last.bos) {
+            1: parse_ipv4;
+            default: parse_srcRouting;
+        }
+    }
+
+    state parse_ipv4 {
+        packet.extract(hdr.ipv4);
+        transition accept;
+    }
+
+}
+
+
+/*************************************************************************
+************   C H E C K S U M    V E R I F I C A T I O N   *************
+*************************************************************************/
+
+control MyVerifyChecksum(inout headers hdr, inout metadata meta) {   
+    apply {  }
+}
+
+
+/*************************************************************************
+**************  I N G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyIngress(inout headers hdr,
+                  inout metadata meta,
+                  inout standard_metadata_t standard_metadata) {
+
+    action drop() {
+        mark_to_drop();
+    }
+    
+    action srcRoute_nhop() {
+        standard_metadata.egress_spec = (bit<9>)hdr.srcRoutes[0].port;
+        hdr.srcRoutes.pop_front(1);
+    }
+
+    action srcRoute_finish() {
+        hdr.ethernet.etherType = TYPE_IPV4;
+    }
+
+    action update_ttl(){
+        hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
+    }
+    
+    apply {
+        if (hdr.srcRoutes[0].isValid()){
+            if (hdr.srcRoutes[0].bos == 1){
+                srcRoute_finish();
+            }
+            srcRoute_nhop();
+            if (hdr.ipv4.isValid()){
+                update_ttl();
+            }
+        }else{
+            drop();
+        } 
+    }
+}
+
+/*************************************************************************
+****************  E G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyEgress(inout headers hdr,
+                 inout metadata meta,
+                 inout standard_metadata_t standard_metadata) {
+    apply {  }
+}
+
+/*************************************************************************
+*************   C H E C K S U M    C O M P U T A T I O N   **************
+*************************************************************************/
+
+control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
+    apply {  }
+}
+
+/*************************************************************************
+***********************  D E P A R S E R  *******************************
+*************************************************************************/
+
+control MyDeparser(packet_out packet, in headers hdr) {
+    apply {
+        packet.emit(hdr.ethernet);
+        packet.emit(hdr.srcRoutes);
+        packet.emit(hdr.ipv4);
+    }
+}
+
+/*************************************************************************
+***********************  S W I T C H  *******************************
+*************************************************************************/
+
+V1Switch(
+MyParser(),
+MyVerifyChecksum(),
+MyIngress(),
+MyEgress(),
+MyComputeChecksum(),
+MyDeparser()
+) main;

P4D2_2017_Fall/exercises/source_routing/source_routing.p4

@@ -0,0 +1,191 @@
+/* -*- P4_16 -*- */
+#include <core.p4>
+#include <v1model.p4>
+
+const bit<16> TYPE_IPV4 = 0x800;
+const bit<16> TYPE_SRCROUTING = 0x1234;
+
+#define MAX_HOPS 9
+
+/*************************************************************************
+*********************** H E A D E R S  ***********************************
+*************************************************************************/
+
+typedef bit<9>  egressSpec_t;
+typedef bit<48> macAddr_t;
+typedef bit<32> ip4Addr_t;
+
+header ethernet_t {
+    macAddr_t dstAddr;
+    macAddr_t srcAddr;
+    bit<16>   etherType;
+}
+
+header srcRoute_t {
+    bit<1>    bos;
+    bit<15>   port;
+}
+
+header ipv4_t {
+    bit<4>    version;
+    bit<4>    ihl;
+    bit<8>    diffserv;
+    bit<16>   totalLen;
+    bit<16>   identification;
+    bit<3>    flags;
+    bit<13>   fragOffset;
+    bit<8>    ttl;
+    bit<8>    protocol;
+    bit<16>   hdrChecksum;
+    ip4Addr_t srcAddr;
+    ip4Addr_t dstAddr;
+}
+
+struct metadata {
+    /* empty */
+}
+
+struct headers {
+    ethernet_t              ethernet;
+    srcRoute_t[MAX_HOPS]    srcRoutes;
+    ipv4_t                  ipv4;
+}
+
+/*************************************************************************
+*********************** P A R S E R  ***********************************
+*************************************************************************/
+
+parser MyParser(packet_in packet,
+                out headers hdr,
+                inout metadata meta,
+                inout standard_metadata_t standard_metadata) {
+
+    
+    state start {
+        transition parse_ethernet;
+    }
+
+    state parse_ethernet {
+        packet.extract(hdr.ethernet);
+        /*
+         * TODO: Modify the next line to select on hdr.ethernet.etherType
+         * If the value is TYPE_SRCROUTING transition to parse_srcRouting
+         * otherwise transition to accept.
+         */
+        transition accept;
+    }
+
+    state parse_srcRouting {
+        /*
+         * TODO: extract the next entry of hdr.srcRoutes
+         * while hdr.srcRoutes.last.bos is 0 transition to this state
+         * otherwise parse ipv4
+         */
+        transition accept;
+    }
+
+    state parse_ipv4 {
+        packet.extract(hdr.ipv4);
+        transition accept;
+    }
+
+}
+
+
+/*************************************************************************
+************   C H E C K S U M    V E R I F I C A T I O N   *************
+*************************************************************************/
+
+control MyVerifyChecksum(inout headers hdr, inout metadata meta) {   
+    apply {  }
+}
+
+
+/*************************************************************************
+**************  I N G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyIngress(inout headers hdr,
+                  inout metadata meta,
+                  inout standard_metadata_t standard_metadata) {
+
+    action drop() {
+        mark_to_drop();
+    }
+    
+    action srcRoute_nhop() {
+        /*
+         * TODO: set standard_metadata.egress_spec 
+         * to the port in hdr.srcRoutes[0] and
+         * pop an entry from hdr.srcRoutes
+         */
+    }
+
+    action srcRoute_finish() {
+        hdr.ethernet.etherType = TYPE_IPV4;
+    }
+
+    action update_ttl(){
+        hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
+    }
+    
+    apply {
+        if (hdr.srcRoutes[0].isValid()){
+            /*
+             * TODO: add logic to:
+             * - If final srcRoutes (top of stack has bos==1):
+             *   - change etherType to IP
+             * - choose next hop and remove top of srcRoutes stack
+             */
+
+            if (hdr.ipv4.isValid()){
+                update_ttl();
+            }
+        }else{
+            drop();
+        } 
+    }
+}
+
+/*************************************************************************
+****************  E G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyEgress(inout headers hdr,
+                 inout metadata meta,
+                 inout standard_metadata_t standard_metadata) {
+    apply {  }
+}
+
+/*************************************************************************
+*************   C H E C K S U M    C O M P U T A T I O N   **************
+*************************************************************************/
+
+control MyComputeChecksum(inout headers hdr, inout metadata meta) {
+    apply {  }
+}
+
+/*************************************************************************
+***********************  D E P A R S E R  *******************************
+*************************************************************************/
+
+control MyDeparser(packet_out packet, in headers hdr) {
+    apply {
+        packet.emit(hdr.ethernet);
+        packet.emit(hdr.srcRoutes);
+        packet.emit(hdr.ipv4);
+    }
+}
+
+/*************************************************************************
+***********************  S W I T C H  *******************************
+*************************************************************************/
+
+V1Switch(
+MyParser(),
+MyVerifyChecksum(),
+MyIngress(),
+MyEgress(),
+MyComputeChecksum(),
+MyDeparser()
+) main;