Test: add first version of packet decode diagnostic utility

doc/installation.rst

@@ -927,6 +927,13 @@ with Doxygen, Sphinx and Read-the-Docs:
     (bliss) lid10eiger1:~ % pip install sphinx_rtd_theme breathe
     ...
 
+Include the Python *Scapy* interface por network packet capture and decoding:
+
+::
+
+    (bliss) lid10eiger1:~ % pip install scapy
+    ...
+
 Eiger calibration development: *Seaborn* and *Spyder*
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

test/packet.py

+import sys
+import os
+import struct
+import glob
+from scipy import stats
+from scapy.all import rdpcap, IP, UDP
+
+HEADER_PACKET_SIZE = 40
+DATA_PACKET_HEADER_SIZE = 48
+DATA_PACKET_DATA_SIZE = 4096
+DATA_PACKET_SIZE = DATA_PACKET_HEADER_SIZE + DATA_PACKET_DATA_SIZE
+
+TSTAMP_CLOCK_FREQ = 10e6
+NOMINAL_PACKET_XFER_TIME = 7.646e-6
+
+pixel_depth = 16
+frame_packets = 4 * pixel_depth
+
+addr_map = {}
+for d in glob.glob('/sys/class/net/*'):
+    name = os.path.basename(d)
+    addrfname = os.path.join(d, 'address')
+    addr = open(addrfname).readline().strip()
+    if addr != ':'.join(['00'] * 6):
+        addr_map[addr] = name
+
+fname = sys.argv[1]
+capfile = rdpcap(fname)
+
+ifaces = {}
+start_ts = None
+for i, x in enumerate(capfile):
+    if not x.haslayer(IP):
+        continue
+    if start_ts is None:
+        start_ts = x.time
+    if not x.haslayer(UDP):
+        continue
+    u = x.getlayer(UDP)
+
+    addr = x.dst
+    iface = addr_map[addr]
+
+    if iface not in ifaces:
+        ifaces[iface] = {'ports': {}, 'start_dtime': None}
+    idata = ifaces[iface]
+    ports = idata['ports']
+
+    port = u.dport
+    if port not in ports:
+        ports[port] = {'packets': []}
+
+    p = u.payload
+    if len(p) == HEADER_PACKET_SIZE:
+        f = '>' + 'L' * 10
+        d = struct.unpack(f, str(p))
+        fnum = d[5]
+        continue
+    elif len(p) != DATA_PACKET_SIZE:
+        raise ValueError('Invalid packet')
+
+    h = str(p)[:DATA_PACKET_HEADER_SIZE]
+    f = '<' + 'QLLQQHHHHLHBB'
+    d = struct.unpack(f, h)
+    fnum, explen, pnum, bunchid, dtime, modid, cx, cy, cz = d[0:9]
+    debug, rrnum, dtype, ver = d[9:13]
+
+    dtime /= TSTAMP_CLOCK_FREQ
+
+    if idata['start_dtime'] is None:
+        idata['start_dtime'] = dtime
+
+    t = x.time - start_ts
+    dt = dtime - idata['start_dtime']
+
+    ports[port]['packets'].append([fnum, pnum, t, dt])
+
+for iface, idata in ifaces.items():
+    for port, d in idata['ports'].items():
+        fnum, pnum, t, dt = d['packets'][-1]
+        x_0 = int(0.4 * fnum * frame_packets)
+
+        xfer_times = []
+        xfer_delays = []
+
+        def calc_xfer_time(data):
+            if len(data[0]) < 2:
+                return None
+            slope, intercept, r_value, p_value, std_err = stats.linregress(*data)
+            xfer_times.append(slope)
+            xfer_delays.append(intercept)
+
+        data = [[], []]
+        for fnum, pnum, t, dt in d['packets']:
+            x = fnum * frame_packets
+            if (x < x_0) or (data[0] and (data[0][-1] == x)):
+                continue
+            if data[0]:
+                xfer_time = (dt - data[1][-1]) / (x - data[0][-1])
+                err = abs((xfer_time - NOMINAL_PACKET_XFER_TIME) / xfer_time)
+                if err > 0.05:
+                    calc_xfer_time(data)
+                    data = [[], []]
+
+            data[0].append(x)
+            data[1].append(dt)
+        calc_xfer_time(data)
+        nb_xfer_times = len(xfer_times)
+        if nb_xfer_times > 0:
+            d['packet_xfer_time'] = sum(xfer_times) / nb_xfer_times
+        else:
+            d['packet_xfer_time'] = NOMINAL_PACKET_XFER_TIME
+        delay_str = ''
+        if nb_xfer_times > 1:
+             x = stats.linregress(range(nb_xfer_times), xfer_delays)
+             delay_str = ':%.5f' % x[0]
+        print "packet_xfer_time[%d:%d%s]=%s" % (port, nb_xfer_times, delay_str,
+                                                d['packet_xfer_time'])
+        ofname = '.'.join(fname.split('.')[:-1]) + '_%s_%d.dat' % (iface, port)
+        d['out_fname'] = ofname
+        d['out_file'] = open(d['out_fname'], 'wt')
+
+for iface, idata in ifaces.items():
+    for port, d in idata['ports'].items():
+        for fnum, pnum, t, dt in d['packets']:
+            xt = fnum * frame_packets * d['packet_xfer_time']
+            fnum += float(pnum) / frame_packets - 1
+            ofile = d['out_file']
+            ofile.write('%6.2f\t%13.9f\t%11.7f\t%11.7f\t%11.7f\n' % 
+                        (fnum, t, dt, t - dt, dt - xt))
+
+