Method for start / stop capture on a link

Ref https://github.com/GNS3/gns3-gui/issues/1117

gns3server/controller/link.py

@@ -15,16 +15,18 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
 import uuid
 import asyncio
 
 
 class Link:
 
-    def __init__(self, project):
+    def __init__(self, project, data_link_type="DLT_EN10MB"):
         self._id = str(uuid.uuid4())
         self._vms = []
         self._project = project
+        self._data_link_type = data_link_type
 
     @asyncio.coroutine
     def addVM(self, vm, adapter_number, port_number):
@@ -51,6 +53,35 @@ class Link:
         """
         raise NotImplementedError
 
+    @asyncio.coroutine
+    def start_capture(self):
+        """
+        Start capture on the link
+
+        :returns: Capture object
+        """
+        raise NotImplementedError
+
+    @asyncio.coroutine
+    def stop_capture(self):
+        """
+        Stop capture on the link
+        """
+        raise NotImplementedError
+
+    def capture_file_name(self):
+        """
+        :returns: File name for a capture on this link
+        """
+        capture_file_name = "{}_{}-{}_to_{}_{}-{}".format(
+            self._vms[0]["vm"].name,
+            self._vms[0]["adapter_number"],
+            self._vms[0]["port_number"],
+            self._vms[1]["vm"].name,
+            self._vms[1]["adapter_number"],
+            self._vms[1]["port_number"])
+        return re.sub("[^0-9A-Za-z_-]", "", capture_file_name) + ".pcap"
+
     @property
     def id(self):
         return self._id
@@ -63,4 +94,4 @@ class Link:
                 "adapter_number": side["adapter_number"],
                 "port_number": side["port_number"]
             })
-        return {"vms": res, "link_id": self._id}
+        return {"vms": res, "link_id": self._id, "data_link_type": self._data_link_type}

gns3server/controller/udp_link.py

@@ -16,6 +16,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import asyncio
+import aiohttp
 
 
 from .link import Link
@@ -23,8 +24,9 @@ from .link import Link
 
 class UDPLink(Link):
 
-    def __init__(self, project):
-        super().__init__(project)
+    def __init__(self, project, data_link_type="DLT_EN10MB"):
+        super().__init__(project, data_link_type)
+        self._capture_vm = None
 
     @asyncio.coroutine
     def create(self):
@@ -76,3 +78,45 @@ class UDPLink(Link):
 
         yield from vm1.delete("/adapters/{adapter_number}/ports/{port_number}/nio".format(adapter_number=adapter_number1, port_number=port_number1))
         yield from vm2.delete("/adapters/{adapter_number}/ports/{port_number}/nio".format(adapter_number=adapter_number2, port_number=port_number2))
+
+    @asyncio.coroutine
+    def start_capture(self):
+        """
+        Start capture on a link
+        """
+        self._capture_vm = self._choose_capture_side()
+        data = {
+            "capture_file_name": self.capture_file_name(),
+            "data_link_type": self._data_link_type
+        }
+        yield from self._capture_vm["vm"].post("/adapters/{adapter_number}/ports/{port_number}/start_capture".format(adapter_number=self._capture_vm["adapter_number"], port_number=self._capture_vm["port_number"]), data=data)
+
+    @asyncio.coroutine
+    def stop_capture(self):
+        """
+        Stop capture on a link
+        """
+        if self._capture_vm:
+            yield from self._capture_vm["vm"].post("/adapters/{adapter_number}/ports/{port_number}/stop_capture".format(adapter_number=self._capture_vm["adapter_number"], port_number=self._capture_vm["port_number"]))
+            self._capture_vm = None
+
+    def _choose_capture_side(self):
+        """
+        Run capture on the best candidate.
+
+        The ideal candidate is a node who support capture on controller
+        server
+
+        :returns: VM where the capture should run
+        """
+
+        # For saving bandwith we use the local node first
+        for vm in self._vms:
+            if vm["vm"].compute.id == "local" and vm["vm"].vm_type not in ["qemu", "vpcs"]:
+                return vm
+
+        for vm in self._vms:
+            if vm["vm"].vm_type not in ["qemu", "vpcs"]:
+                return vm
+
+        raise aiohttp.web.HTTPConflict(text="Capture is not supported for this link")

gns3server/controller/vm.py

@@ -216,6 +216,9 @@ class VM:
         else:
             return (yield from self._compute.delete("/projects/{}/{}/vms/{}{}".format(self._project.id, self._vm_type, self._id, path)))
 
+    def __repr__(self):
+        return "<gns3server.controller.VM {} {}>".format(self._vm_type, self._name)
+
     def __json__(self):
         return {
             "compute_id": self._compute.id,