dpp-nfc: Support channel list negotiation

If the peer's channel list in negotiated handover does not have any
common channels and the local end is configured with an alternative
channel list, try to initiate another negotiation handover with the
alternative channels.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

wpa_supplicant/examples/dpp-nfc.py

@@ -179,12 +179,15 @@ def dpp_bootstrap_gen(wpas, type="qrcode", chan=None, mac=None, info=None,
         raise Exception("Failed to generate bootstrapping info")
     return int(res)
 
-def wpas_get_nfc_uri(start_listen=True, pick_channel=False):
+def wpas_get_nfc_uri(start_listen=True, pick_channel=False, chan_override=None):
     wpas = wpas_connect()
     if wpas is None:
         return None
     global own_id, chanlist
-    chan = chanlist
+    if chan_override:
+        chan = chan_override
+    else:
+        chan = chanlist
     if chan is None and get_status_field(wpas, "bssid[0]"):
         freq = get_status_field(wpas, "freq")
         if freq:
@@ -219,8 +222,12 @@ def wpas_report_handover_sel(uri):
     cmd = "DPP_NFC_HANDOVER_SEL own=%d uri=%s" % (own_id, uri)
     return wpas.request(cmd)
 
-def dpp_handover_client(llc):
-    uri = wpas_get_nfc_uri(start_listen=False)
+def dpp_handover_client(llc, alt=False):
+    chan_override = None
+    if alt:
+        global altchanlist
+        chan_override = altchanlist
+    uri = wpas_get_nfc_uri(start_listen=False, chan_override=chan_override)
     if uri is None:
         summary("Cannot start handover client - no bootstrap URI available")
         return
@@ -346,6 +353,10 @@ def dpp_handover_client(llc):
 
     if not dpp_found:
         summary("DPP carrier not seen in response - allow peer to initiate a new handover with different parameters")
+        my_crn_ready = False
+        my_crn = None
+        peer_crn = None
+        hs_sent = False
         client.close()
         summary("Returning from dpp_handover_client")
         return
@@ -374,6 +385,7 @@ class HandoverServer(nfc.handover.HandoverServer):
         self.ho_server_processing = False
         self.success = False
         self.try_own = False
+        self.llc = llc
 
     def process_handover_request_message(self, records):
         self.ho_server_processing = True
@@ -439,6 +451,11 @@ class HandoverServer(nfc.handover.HandoverServer):
                 res = wpas_report_handover_req(uri)
                 if res is None or "FAIL" in res:
                     summary("DPP handover request processing failed")
+                    global altchanlist
+                    if altchanlist:
+                        data = wpas_get_nfc_uri(start_listen=False,
+                                                chan_override=altchanlist)
+                        summary("Own URI (try another channel list): %s" % data)
                     continue
 
                 found = True
@@ -492,9 +509,14 @@ class HandoverServer(nfc.handover.HandoverServer):
 
         summary("Sending handover select: " + str(sel))
         if found:
+            summary("Handover completed successfully")
             self.success = True
         else:
+            summary("Try to initiate with alternative parameters")
             self.try_own = True
+            if not init_on_touch and no_input:
+                # Need to start client thread now
+                threading.Thread(target=llcp_worker, args=(self.llc,)).start()
         global hs_sent
         hs_sent = True
         return sel
@@ -648,7 +670,12 @@ def llcp_worker(llc):
         if srv.try_own:
             srv.try_own = False
             summary("Try to initiate another handover with own parameters")
-            dpp_handover_client(llc)
+            global peer_crn, my_crn, my_crn_ready, hs_sent
+            my_crn_ready = False
+            my_crn = None
+            peer_crn = None
+            hs_sent = False
+            dpp_handover_client(llc, alt=True)
             summary("Exiting llcp_worker thread (retry with own parameters)")
             return
         if srv.ho_server_processing:
@@ -737,6 +764,7 @@ def main():
                         help='success file for writing success update')
     parser.add_argument('--device', default='usb', help='NFC device to open')
     parser.add_argument('--chan', default=None, help='channel list')
+    parser.add_argument('--altchan', default=None, help='alternative channel list')
     parser.add_argument('command', choices=['write-nfc-uri',
                                             'write-nfc-hs'],
                         nargs='?')
@@ -749,8 +777,9 @@ def main():
     global no_wait
     no_wait = args.no_wait
 
-    global chanlist
+    global chanlist, altchanlist
     chanlist = args.chan
+    altchanlist = args.altchan
 
     logging.basicConfig(level=args.loglevel)