Pythonify shunt setup methods and integrate into tests (#927)

bin/shunt_functions

@@ -7,6 +7,7 @@ function build_vxlan_ssh_conn {
     SSH_IN_PORT=$1
     SSH_OUT_PORT=$2
     LOCAL_VXLAN_IP=${3:-"192.168.1.2"}
+    VNI=${4:-0}
     REMOTE_IP=${4:-"192.168.21.1"}
     LOCAL_IP=${5:-"192.168.21.2"}
 
@@ -16,7 +17,7 @@ function build_vxlan_ssh_conn {
     sudo ip link set ep0 up
 
     # socat session to move packets from ssh tunnel to UDP port
-    socat -T15 tcp4-listen:30001,reuseaddr,fork UDP:localhost:4789 &
+    socat -T15 tcp4-listen:$SSH_IN_PORT,reuseaddr,fork UDP:localhost:4789 &
 
     # iptables command to change source IP from localhost
     sudo iptables -t nat -A POSTROUTING -p udp -d 127.0.0.1 --dport 4789 -j SNAT --to-source $REMOTE_IP:38000-45000
@@ -25,10 +26,10 @@ function build_vxlan_ssh_conn {
     sudo iptables -t nat -A OUTPUT -o ep0 -p udp --dport 4789 -j REDIRECT --to-ports 20000
 
     # socat session to move packets from UDP port to ssh session
-    socat -T15 udp4-recvfrom:20000,reuseaddr,fork tcp:localhost:30000 &
+    socat -T15 udp4-recvfrom:20000,reuseaddr,fork tcp:localhost:$SSH_OUT_PORT &
 
     # create vxlan tunnel
-    sudo ip link add vxlan type vxlan id 0 remote $REMOTE_IP dstport 4789 srcport 4789 4789 nolearning
+    sudo ip link add vxlan type vxlan id $VNI remote $REMOTE_IP dstport 4789 srcport 4789 4789 nolearning
     sudo ip addr add $LOCAL_VXLAN_IP/24 dev vxlan
     sudo ip link set vxlan up
 }
@@ -57,7 +58,6 @@ function build_ssh_tunnel {
     SSH_OUT_PORT=$2
     REMOTE_HOST=$3
 
-    sleep 5
     ssh -o StrictHostKeyChecking=no -L $SSH_OUT_PORT:127.0.0.1:$SSH_IN_PORT -N -f $REMOTE_HOST
     ssh -o StrictHostKeyChecking=no -R $SSH_OUT_PORT:127.0.0.1:$SSH_IN_PORT -N -f $REMOTE_HOST
 }

shunt/__init__.py

@@ -0,0 +1,3 @@
+"""Shunt module"""
+
+pass

shunt/shell_command_helper.py

@@ -0,0 +1,94 @@
+"""Module to help run shell commands and retrieve output"""
+
+from __future__ import absolute_import
+import subprocess
+import multiprocessing
+
+
+class ShellCommandHelper():
+    """Hosts methods to run shell commands and retrieve output"""
+
+    TEN_MIN_SEC = 10 * 60
+
+    def __init__(self):
+        pass
+
+    def _run_process_command(self, command, capture=False):
+        """
+        Args:
+            command: Takes an str line or list[str] to be run in shell
+            capture: Setting to True captures stdout, stderr and return code
+        returns:
+            Popen object
+        """
+        command_list = command.split() if isinstance(command, str) else command
+        pipeout = subprocess.PIPE if capture else None
+        return subprocess.Popen(command_list, stdout=pipeout, stderr=pipeout)
+
+    def _reap_process_command(self, process):
+        """
+        Args:
+            process: Popen object to reap
+        returns:
+            return code of command, stdout, stderr
+        """
+        process.wait(timeout=self.TEN_MIN_SEC)
+        stdout, stderr = process.communicate()
+        strout = str(stdout, 'utf-8') if stdout else None
+        strerr = str(stderr, 'utf-8') if stderr else None
+        return process.returncode, strout, strerr
+
+    # pylint: disable=too-many-arguments
+    def run_cmd(self, cmd, arglist=None, strict=True,
+                capture=False, docker_container=None, detach=False):
+        """
+        Args:
+            cmd: command to be executed
+            arglist: Additional arguments to add to command
+            strict: Raises exception if command execution fails
+            capture: Prints out and captures stdout and stderr output of command
+            docker_container: Set if command needs to be run within a docker container
+        returns:
+            return code of command, stdout, stderr
+        """
+        command = ("docker exec %s " % docker_container) if docker_container else ""
+        command = command.split() + ([cmd] + arglist) if arglist else command + cmd
+        if detach:
+            self._run_process_command(command, capture=capture)
+            return None, None, None
+        retcode, out, err = self._reap_process_command(
+            self._run_process_command(command, capture=capture))
+        if strict and retcode:
+            if capture:
+                print('stdout: \n%s' % out)
+                print('stderr: \n%s' % err)
+            raise Exception('Command execution failed: %s' % str(command))
+        return retcode, out, err
+
+    def parallelize(self, target, target_args, batch_size=200):
+        """
+        Parallelizes multiple runs of a target method with multiprocessing.
+        Args:
+            target_args: List of tuples which serve as args for target.
+                        List size determines number of jobs
+            target: Target method
+            batch_size: Thread pool size
+        """
+        jobs = []
+        for arg_tuple in target_args:
+            process = multiprocessing.Process(target=target, args=arg_tuple)
+            jobs.append(process)
+
+        batch_start = 0
+        while batch_start <= len(jobs):
+            batch_end = batch_start + batch_size
+            batch_jobs = jobs[batch_start:batch_end]
+
+            for job in batch_jobs:
+                job.start()
+
+            for job in batch_jobs:
+                job.join()
+                job.close()
+
+            batch_start = batch_end

shunt/vxlan_over_ssh.py

@@ -0,0 +1,145 @@
+"""Module to build VxLAN tunnels over SSH tunnels using shell commands"""
+
+from __future__ import absolute_import
+from shunt.shell_command_helper import ShellCommandHelper
+
+
+def build_ssh_tunnel(ssh_in_port, ssh_out_port, remote_host, reverse=False):
+    """
+    Args:
+        ssh_in_port: Destination port for tunnel
+        ssh_out_port: Source port for tunnel
+        remote_host: Remote host IP
+        reverse: Boolean. Creates reverse forwarding tunnel if True.
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    direction = 'R' if reverse else 'L'
+    shellcmd.run_cmd("ssh -o StrictHostKeyChecking=no -%s %s:127.0.0.1:%s -N -f %s"
+                     % (direction, ssh_out_port, ssh_in_port, remote_host))
+
+
+def build_bidirectional_ssh_tunnel(ssh_in_port, ssh_out_port, remote_host):
+    """
+    Args:
+        ssh_in_port: Incoming traffice port
+        ssh_out_port: Outgoing traffic port
+        remote_host: Remote host IP
+    Returns: None
+    """
+    build_ssh_tunnel(ssh_in_port, ssh_out_port, remote_host, reverse=False)
+    build_ssh_tunnel(ssh_in_port, ssh_out_port, remote_host, reverse=True)
+
+
+def create_virtual_if(if_name, if_ip):
+    """
+    Args:
+        if_name: interface name
+        if_ip: interface IP
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd("sudo ip link add %s type dummy" % (if_name))
+    shellcmd.run_cmd("sudo ip addr add %s/24 dev %s" % (if_ip, if_name))
+    shellcmd.run_cmd("sudo ip link set %s up" % (if_name))
+
+
+def socat_tcp_to_udp(src_port, dst_port):
+    """
+    Socat command to map TCP port to UDP port
+    Args:
+        src_port: Source TCP port
+        dst_port: Destination UDP port
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd("socat -T15 tcp4-listen:%s,reuseaddr,fork udp:localhost:%s"
+                     % (src_port, dst_port), detach=True)
+
+
+def socat_udp_to_tcp(src_port, dst_port):
+    """
+    Socat command to map UDP port to TCP port
+    Args:
+        src_port: Source UDP port
+        dst_port: Destincation TCP port
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd("socat -T15 udp4-listen:%s,reuseaddr,fork tcp:localhost:%s"
+                     % (src_port, dst_port), detach=True)
+
+
+def iptables_udp_change_source(dst_ip, dst_port, src_ip_port):
+    """
+    iptables command to change source IP/ports of UDP packets
+    Args:
+        dst_ip: Destination IP of packet to be changed
+        dst_port: Destination port of packet to be changed
+        src_ip_port: <source_ip_to_be_added>:<source port range> e.g. 192.168.1.2:38000-45000
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd(
+        "sudo iptables -t nat -A POSTROUTING -p udp -d %s --dport %s -j SNAT --to-source %s"
+        % (dst_ip, dst_port, src_ip_port))
+
+
+def iptables_udp_divert_iface_traffic(iface, dst_port, target_dst_port):
+    """
+    iptables command to divert udp traffic egressing from an interface to a different port
+    Args:
+        iface: Interface packets are egressign from
+        dst_port: Destination port of packets to be diverted
+        target_dst_port: Destination port packets are diverted to
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd(
+        "sudo iptables -t nat -A OUTPUT -o %s -p udp --dport %s -j REDIRECT --to-ports %s"
+        % (iface, dst_port, target_dst_port))
+
+
+def create_vxlan_tunnel(vni, remote_ip, vxlan_port, vtep_ip):
+    """
+    Method to create a VxLAN tunnel and assign an IP to the VTEP
+    Args:
+        vni: VNI of tunnel to be created
+        remote_ip: Remote IP address for underlay network
+        vxlan_port: Remote destination port for VxLAN tunnel
+    Returns: None
+    """
+    shellcmd = ShellCommandHelper()
+    shellcmd.run_cmd(
+        "sudo ip link add vxlan type vxlan id %s remote %s dstport %s srcport %s %s nolearning"
+        % (vni, remote_ip, vxlan_port, vxlan_port, vxlan_port))
+    shellcmd.run_cmd("sudo ip addr add %s/24 dev vxlan" % (vtep_ip))
+    shellcmd.run_cmd("sudo ip link set vxlan up")
+
+
+def build_vxlan_ssh_conn(conn_params):
+    """
+    Args:
+        conn_params: JSON. Format:{  # TODO: Turn into a proto for easy config exchange.
+                virt_if_name: Interface name of virtual interface for underlay n/w
+                virt_if_ip: IP for virtual interface
+                ssh_in_port: Port for incoming traffic
+                ssh_out_port: Port for outgoing traffic
+                remote_ip: Remote IP of underlay n/w
+                vni: VxLAN identifier
+                vxlan_if_ip: VxLAN interface IP
+        }
+    Returns: None
+    """
+    VXLAN_PORT = '4789'
+    LOCAL_HOST = '127.0.0.1'
+    VXLAN_SOURCE_PORT_RANGE = "38000-45000"
+    INTERMEDIATE_PORT = "20000"
+    create_virtual_if(conn_params['virt_if_name'], conn_params['virt_if_ip'])
+    socat_tcp_to_udp(conn_params['ssh_in_port'], VXLAN_PORT)
+    source_ip_port = conn_params['remote_ip'] + ":" + VXLAN_SOURCE_PORT_RANGE
+    iptables_udp_change_source(LOCAL_HOST, VXLAN_PORT, source_ip_port)
+    iptables_udp_divert_iface_traffic(conn_params['virt_if_name'], VXLAN_PORT, INTERMEDIATE_PORT)
+    socat_udp_to_tcp(INTERMEDIATE_PORT, conn_params['ssh_out_port'])
+    create_vxlan_tunnel(
+        conn_params['vni'], conn_params['remote_ip'], VXLAN_PORT, conn_params['vxlan_if_ip'])

testing/shunt/Dockerfile.shunthost

@@ -5,13 +5,20 @@
 
 FROM daqf/aardvark
 
-RUN $AG update && $AG install openssh-server socat sudo iptables
+RUN $AG update && $AG install openssh-server socat sudo iptables python3-dev
 
 COPY ./testing/shunt/id_rsa .ssh/
 COPY ./testing/shunt/id_rsa.pub .ssh/
 COPY ./testing/shunt/authorized_keys .ssh/
 COPY ./testing/shunt/start_shunt_host ./
 
+RUN mkdir -p shunt
+RUN mkdir -p testing
+RUN mkdir -p testing/shunt
+
+COPY ./shunt shunt
+COPY ./testing/shunt testing/shunt
+
 RUN chmod -R 700 .ssh
 
 RUN service ssh start

testing/shunt/build_vxlan_ssh_conn.py

@@ -0,0 +1,41 @@
+"""Script to build vxlan over ssh for testing across docker hosts"""
+
+
+from __future__ import absolute_import
+import sys
+from shunt.vxlan_over_ssh import build_vxlan_ssh_conn, build_bidirectional_ssh_tunnel
+
+CONN_PARAMS = {
+    'virt_if_name': 'ep0',
+    'ssh_in_port': '30001',
+    'ssh_out_port': '30000',
+    'vni': '0'
+}
+
+CONN_PARAMS_CLIENT = {
+    'virt_if_ip': '192.168.21.2',
+    'remote_ip': '192.168.21.1',
+    'vxlan_if_ip': '192.168.1.2'
+}
+CONN_PARAMS_CLIENT.update(CONN_PARAMS)
+
+CONN_PARAMS_SERVER = {
+    'virt_if_ip': '192.168.21.1',
+    'remote_ip': '192.168.21.2',
+    'vxlan_if_ip': '192.168.1.1'
+}
+CONN_PARAMS_SERVER.update(CONN_PARAMS)
+
+
+def main():
+    """Build vxlan over ssh for client/server"""
+    if sys.argv[1] == 'client':
+        build_bidirectional_ssh_tunnel(
+            CONN_PARAMS['ssh_in_port'], CONN_PARAMS['ssh_out_port'], 'shunt_host_server_1')
+        build_vxlan_ssh_conn(CONN_PARAMS_CLIENT)
+    elif sys.argv[1] == 'server':
+        build_vxlan_ssh_conn(CONN_PARAMS_SERVER)
+
+
+if __name__ == "__main__":
+    main()

testing/shunt/docker-compose.yaml

@@ -1,17 +1,21 @@
 version: '2'
 
 services:
-    host1:
+    host_client:
         build:
             context: ../..
             dockerfile: ./testing/shunt/Dockerfile.shunthost
-        command: bash -c "./start_shunt_host 1"
+        depends_on:
+            - "host_server"
+        command: bash -c "./start_shunt_host client"
+        #command: bash -c "tail -f"
         cap_add:
             - ALL
-    host2:
+    host_server:
         build:
             context: ../..
             dockerfile: ./testing/shunt/Dockerfile.shunthost
-        command: bash -c "./start_shunt_host 2"
+        command: bash -c "./start_shunt_host server"
+        #command: bash -c "tail -f"
         cap_add:
             - ALL

testing/shunt/start_shunt_host

@@ -3,13 +3,9 @@
 
 host=$1
 service ssh start
-source bin/shunt_functions
-
-if [ $host -eq 1 ]; then
-    build_ssh_tunnel 30001 30000 shunt_host2_1
-    build_vxlan_ssh_conn 30001 30000 192.168.1.1
-else
-    build_vxlan_ssh_conn 30001 30000 192.168.1.2
-fi
+
+export PYTHONPATH=$PYTHONPATH:/root/shunt
+
+python3 testing/shunt/build_vxlan_ssh_conn.py $host
 
 tail -f /dev/null