pcap: pass complete filter string to PcapRecorder

Composing the filter in gen_filter() is more complex than we need. We pass the
address and potentially further filter elements separately, and then
gen_filter() has to guess how to combine these. Instead, have just a filter
string to use right from the start, so that the caller has full control (and
full responsibility).

Remove the addr argument, which was only used for filtering.

This is my conclusion of looking at the patches with change Ids
I62a6ae7bd3a84baceb684c26727d2269c86ed023 (PS 1) and
Icbb0f8d2058fa7ebb7f0f731645f9266cacdb120

I62... PS 2 will add the SSH filtering.

The name 'filter' is a python built-in, which is why I chose the argument
name 'filters' instead. It works with 'filter' as well, but let's try to
avoid naming conflicts like that.

Change-Id: Iff7ddf51d3bf0189ce07b488a3dcdcfce6907aba

src/osmo_gsm_tester/osmo_nitb.py

@@ -52,8 +52,8 @@ class OsmoNitb(log.Origin):
             raise RuntimeError('No lib/ in %r' % inst)
 
         iface = util.ip_to_iface(self.addr())
-        pcap_recorder.PcapRecorder(self.suite_run, self.run_dir.new_dir('pcap'),
-                                   iface, self.addr())
+        pcap_recorder.PcapRecorder(self.suite_run, self.run_dir.new_dir('pcap'), iface,
+                                   'host %s' % self.addr())
 
         env = { 'LD_LIBRARY_PATH': util.prepend_library_path(lib) }
 

src/osmo_gsm_tester/pcap_recorder.py

@@ -26,13 +26,13 @@ from . import log, util, config, template, process, osmo_ctrl
 
 class PcapRecorder(log.Origin):
 
-    def __init__(self, suite_run, run_dir, iface=None, addr=None):
+    def __init__(self, suite_run, run_dir, iface=None, filters=''):
         self.suite_run = suite_run
         self.run_dir = run_dir
         self.iface = iface
         if not self.iface:
             self.iface = "any"
-        self.addr = addr
+        self.filters = filters
         self.set_log_category(log.C_RUN)
         self.set_name('pcap-recorder_%s' % self.iface)
         self.start()
@@ -44,17 +44,10 @@ class PcapRecorder(log.Origin):
                                        ('tcpdump', '-n',
                                        '-i', self.iface,
                                        '-w', dumpfile,
-                                       self.gen_filter())
-                                       )
+                                       self.filters))
         self.suite_run.remember_to_stop(self.process)
         self.process.launch()
 
-    def gen_filter(self):
-        filter = ""
-        if self.addr:
-            filter += 'host ' + self.addr
-        return filter
-
     def running(self):
         return not self.process.terminated()