examples: Add virtmissensor.py script for virtual_misdev

The virtual match-in-sensor (MIS) device requires a script to simulate
the device. virtmissensor.py provides a simple implementation for this
purpose.

examples/virtmissensor.py

@@ -0,0 +1,129 @@
+#!/usr/bin/env python3
+
+# This script can be used together with the virtual_misdev to simulate an
+# match-in-sensor device with internal storage.
+#
+# To use, set the FP_VIRTUAL_MISDEV environment variable for both the
+# libfprint using program (e.g. fprintd) and this script.
+#
+# Usually this would work by adding it into the systemd unit file. The
+# best way of doing so is to create
+#  /etc/systemd/system/fprintd.service.d/fprintd-test.conf
+#
+# [Service]
+# RuntimeDirectory=fprint
+# Environment=FP_VIRTUAL_IMGDEV=/run/fprint/virtimg_sock
+# Environment=G_MESSAGES_DEBUG=all
+# ReadWritePaths=$RUNTIME_DIR
+#
+# After that run:
+#
+#   systemctl daemon-reload
+#   systemctl restart fprintd.service
+#
+# You may also need to disable selinux.
+#
+# Then run this script with e.g.
+# FP_VIRTUAL_IMGDEV=/run/fprint/virtimg_sock ./virtmissensor.py /tmp/storage
+#
+# Please note that the storage file should be pre-created with a few lines
+# Each line represents a slot, if a print is stored, then it will contain a
+# UUID (defined by the driver) and a matching string to identify it again.
+# Note that the last slot line should not end with a \n
+
+import sys
+import os
+import socket
+import struct
+
+import argparse
+
+parser = argparse.ArgumentParser(description='Play virtual fingerprint device with internal storage.')
+parser.add_argument('storage', metavar='storage', type=argparse.FileType('r+'),
+                    help='The "storage" database (one line per slot)')
+parser.add_argument('-e', dest='enroll', type=str,
+                    help='Enroll a print using the string as identifier')
+parser.add_argument('-v', dest='verify', type=str,
+                    help='Verify print if the stored identifier matches the given identifier')
+
+args = parser.parse_args()
+
+cnt = 0
+if args.enroll:
+    cnt += 1
+if args.verify:
+    cnt += 1
+
+assert cnt == 1, 'You need to give exactly one command argument, -e or -v'
+
+prints = []
+for slot in args.storage.read().split('\n'):
+    split = slot.split(' ', 1)
+    if len(split) == 2:
+        prints.append(split)
+    else:
+        prints.append(None)
+
+
+# Send image through socket
+sockaddr = os.environ['FP_VIRTUAL_MISDEV']
+
+sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+sock.connect(sockaddr)
+
+# Assume we get a full message
+msg = sock.recv(1024)
+assert(msg[-1] == ord(b'\n'))
+
+if args.enroll:
+    if not msg.startswith(b'ENROLL '):
+        sys.stderr.write('Expected to enroll, but driver is not ready for enrolling (%s)\n' % str(msg.split(b' ', 1)[0]))
+        sys.exit(1)
+    uuid = msg[7:-1].decode('utf-8')
+
+    for slot in prints:
+        if slot is not None and slot[0] == uuid:
+            sock.sendall(b'2\n') # ENROLL_FAIL
+            sys.stderr.write('Failed to enroll; UUID has already been stored!\n')
+            sys.exit(1)
+
+    # Find an empty slot
+    for i, slot in enumerate(prints):
+        if slot is not None:
+            continue
+
+        prints[i] = (uuid, args.enroll)
+        sock.sendall(b'1\n') # ENROLL_COMPLETE
+        break
+    else:
+        # TODO: 2: ENROLL_FAIL, but we should send no empty slot!
+        sock.sendall(b'2\n') # ENROLL_FAIL
+        sys.stderr.write('Failed to enroll, no free slots!\n')
+        sys.exit(1)
+
+elif args.verify:
+    if not msg.startswith(b'VERIFY '):
+        sys.stderr.write('Expected to verify, but driver is not ready for verifying (%s)\n' % str(msg.split(b' ', 1)[0]))
+        sys.exit(1)
+    uuid = msg[7:-1].decode('utf-8')
+
+    for slot in prints:
+        if slot is not None and slot[0] == uuid:
+            if slot[1] == args.verify:
+                sock.sendall(b'1\n') # VERIFY_MATCH
+            else:
+                sock.sendall(b'0\n') # VERIFY_NO_MATCH
+            sys.exit(0)
+    else:
+        sys.stderr.write('Slot ID is unknown, returning error\n')
+        sock.sendall(b'-1') # error, need way to report that print is unkown
+
+
+prints_str = '\n'.join('' if p is None else '%s %s' % (p[0], p[1]) for p in prints)
+prints_human_str = '\n'.join('empty slot' if p is None else '%s %s' % (p[0], p[1]) for p in prints)
+
+print('Prints stored now:')
+print(prints_human_str)
+args.storage.seek(0)
+args.storage.truncate()
+args.storage.write(prints_str)