mdns: support primitive clients (android, rfc-6.7)

copyparty/__main__.py

@@ -621,7 +621,7 @@ def run_argparse(
     ap2.add_argument("--qr", action="store_true", help="show http:// QR-code on startup")
     ap2.add_argument("--qrs", action="store_true", help="show https:// QR-code on startup")
     ap2.add_argument("--qrl", metavar="PATH", type=u, default="", help="location to include in the url, for example [\033[32mpriv/?pw=hunter2\033[0m]")
-    ap2.add_argument("--qri", metavar="PREFIX", type=u, default="", help="select IP which starts with PREFIX")
+    ap2.add_argument("--qri", metavar="PREFIX", type=u, default="", help="select IP which starts with PREFIX; [\033[32m.\033[0m] to force default IP when mDNS URL would have been used instead")
     ap2.add_argument("--qr-fg", metavar="COLOR", type=int, default=0 if tty else 16, help="foreground; try [\033[32m0\033[0m] if the qr-code is unreadable")
     ap2.add_argument("--qr-bg", metavar="COLOR", type=int, default=229, help="background (white=255)")
     ap2.add_argument("--qrp", metavar="CELLS", type=int, default=4, help="padding (spec says 4 or more, but 1 is usually fine)")

copyparty/mdns.py

@@ -373,24 +373,66 @@ class MDNS(MCast):
             self.stop(True)
             return
 
+        # then rfc-6.7; dns pretending to be mdns (android...)
+        if p.header.id or addr[1] != 5353:
+            rsp: Optional[DNSRecord] = None
+            for r in p.questions:
+                try:
+                    lhn = U(r.qname).lower()
+                except:
+                    self.log("invalid question: {}".format(r))
+                    continue
+
+                if lhn != self.lhn:
+                    continue
+
+                if p.header.id and r.qtype in (QTYPE.A, QTYPE.AAAA):
+                    rsp = rsp or DNSRecord(DNSHeader(p.header.id, 0x8400))
+                    rsp.add_question(r)
+                    for ip in srv.ips:
+                        qt = r.qtype
+                        v6 = ":" in ip
+                        if v6 == (qt == QTYPE.AAAA):
+                            rd = AAAA(ip) if v6 else A(ip)
+                            rr = RR(self.hn, qt, DC.IN, 10, rd)
+                            rsp.add_answer(rr)
+            if rsp:
+                srv.sck.sendto(rsp.pack(), addr[:2])
+                # but don't return in case it's a differently broken client
+
         # then a/aaaa records
         for r in p.questions:
-            if U(r.qname).lower() != self.lhn:
+            try:
+                lhn = U(r.qname).lower()
+            except:
+                self.log("invalid question: {}".format(r))
+                continue
+
+            if lhn != self.lhn:
                 continue
 
             # gvfs keeps repeating itself
             found = False
             unicast = False
-            for r in p.rr:
-                rname = U(r.rname).lower()
+            for rr in p.rr:
+                try:
+                    rname = U(rr.rname).lower()
+                except:
+                    self.log("invalid rr: {}".format(rr))
+                    continue
+
                 if rname == self.lhn:
-                    if r.ttl > 60:
+                    if rr.ttl > 60:
                         found = True
-                    if r.rclass == DC.F_IN:
+                    if rr.rclass == DC.F_IN:
                         unicast = True
 
             if unicast:
+                # spec-compliant mDNS-over-unicast
                 srv.sck.sendto(srv.bp_ip, (cip, 5353))
+            elif addr[1] != 5353:
+                # just in case some clients use (and want us to use) invalid ports
+                srv.sck.sendto(srv.bp_ip, addr[:2])
 
             if not found:
                 self.q[cip] = (0, srv, srv.bp_ip)
@@ -400,6 +442,9 @@ class MDNS(MCast):
 
         # and service queries
         for r in p.questions:
+            if not r or not r.qname:
+                continue
+
             qname = U(r.qname).lower()
             if qname in self.lsvcs or qname == "_services._dns-sd._udp.local.":
                 self.q[cip] = (deadline, srv, srv.bp_svc)
@@ -408,10 +453,13 @@ class MDNS(MCast):
         # (workaround gvfs race-condition where it occasionally
         #  doesn't read/decode the full response...)
         if now < srv.last_tx + 12:
-            for r in p.rr:
-                rdata = U(r.rdata).lower()
+            for rr in p.rr:
+                if not rr.rdata:
+                    continue
+
+                rdata = U(rr.rdata).lower()
                 if rdata in self.lsfqdns:
-                    if r.ttl > 2250:
+                    if rr.ttl > 2250:
                         self.q.pop(cip, None)
                     break
 

copyparty/stolen/dnslib/dns.py

@@ -106,9 +106,9 @@ class DNSRecord(object):
     ) -> None:
         self.header = header or DNSHeader()
         self.questions: list[DNSQuestion] = questions or []
-        self.rr = rr or []
-        self.auth = auth or []
-        self.ar = ar or []
+        self.rr: list[RR] = rr or []
+        self.auth: list[RR] = auth or []
+        self.ar: list[RR] = ar or []
 
         if q:
             self.questions.append(q)

copyparty/tcpsrv.py

@@ -508,19 +508,20 @@ class TcpSrv(object):
     def _qr(self, t1: dict[str, list[int]], t2: dict[str, list[int]]) -> str:
         ip = None
         ips = list(t1) + list(t2)
-        if self.args.zm:
+        qri = self.args.qri
+        if self.args.zm and not qri:
             name = self.args.name + ".local"
             t1[name] = next(v for v in (t1 or t2).values())
             ips = [name] + ips
 
         for ip in ips:
-            if ip.startswith(self.args.qri):
+            if ip.startswith(qri) or qri == ".":
                 break
             ip = ""
 
         if not ip:
             # maybe /bin/ip is missing or smth
-            ip = self.args.qri
+            ip = qri
 
         if not ip:
             return ""