import usocket
import utime
import uselect
#TYPEs
TYPE_A = 1
TYPE_PTR = 12
TYPE_TXT = 16
TYPE_SRV = 33
TYPE_AAAA= 28
#Make request
def str2dnsstr(string):
strings = string.split(b'.')
return b''.join((bytes((len(x),)) + x for x in strings))+b'\0'
def makeServiceQuery(service):
query = bytes((0, 0, #ID
0, 0, #Flage (Query,...)
0, 1, #One question
0, 0, #No Answer
0, 0, #NScount
0, 0)) #ARcount
query += str2dnsstr(service)
query += bytes((0x00, 0x0C, #PTR record
0x80, 0x01)) #Unicast, Query Class: INternet
return query
def uint16(x):
return (x[0]<<8)+x[1]
#parse answer
def parseDNSstring(data, i, r=''):
#print(data[i:])
qname = b''
if data and len(data) > i:
while data[i]:
#print(r+'parsing 1:', i, hex(data[i]))
if data[i] & 0xc0:
p = uint16(data[i:i+2])&0x3FFF
if p > i:
print('weird pointer, p>i', p, i)
return None
#print(r+'recurse', p)
ret = parseDNSstring(data, p, r=' '+r)
#print(r+'back', ret)
if ret:
return qname+ret[0], i+2
else:
return ret
elif len(data) > (data[i]+i):
qname += data[i+1:i+1+(data[i])] + b'.'
#print(r+'qname+=', data[i+1:i+1+(data[i])])
i += (data[i]+1)
else:
return None
if qname:
return qname[:-1], i+1
else:
return None #no valid data
return None
def parsePacket(data):
if len(data) < 13:
return None
if not data[2] & 0x80: #not an answer
return None
if data[2] & 0x02: #data truncated, ignore for now
return None
if not data[7]: #Zero answers
return None
questions = uint16(data[4:6])
answers = uint16(data[6:8])
#data = data[12:]
i = 12
for q in range(questions):
ret = parseDNSstring(data, i)
if ret:
qname, d = ret
i = d
else:
return None #invalid Data
qtype = uint16(data[i:i+2])
i += 2
print('qtype:', hex(qtype))
qclass = uint16(data[i:i+2])
i += 2
print('qclass', hex(qclass))
adict = {'A': [], 'AAAA': [], 'SRV': [], 'TXT': [], 'PTR': []}
for a in range(answers):
#print('\nanswer', a+1, '/', answers)
if len(data) < i+12: #incomplete data
return None
ret = parseDNSstring(data, i)
if ret:
aname, d = ret
i = d
else:
return None
#print("aname:", aname)
atype = uint16(data[i:i+2])
i += 2
#print('atype:', hex(atype))
aclass = uint16(data[i:i+2])&0x7FFF
i += 2
#print('aclass', aclass)
if aclass != 1:
continue
attl = data[i:i+4]
i += 4
#print('TTL:', attl)
ardl = uint16(data[i:i+2])
i += 2
#print('Data len:', ardl, len(data)-i)
if len(data)-i < (ardl): #incomplete data
return None
ardata = data[i: i+ardl]
if atype == TYPE_A:
if ardl == 4:
ardata = data[i: i+ardl]
ip = '.'.join((str(x) for x in ardata))
#print('A:', {aname: ip})
adict['A'].append({aname: ip})
elif atype == TYPE_PTR or atype == TYPE_TXT:
ret = parseDNSstring(data[:i+ardl], i)
if ret:
ardata, j = ret
if atype == TYPE_PTR:
#print('PTR:', ardata)
adict['PTR'].append({aname: ardata})
elif atype == TYPE_TXT:
#print('TXT:', ardata)
adict['TXT'].append({aname: ardata})
else:
print('Other:', atype, data[i: i+ardl], ardata)
elif atype == TYPE_SRV:
ardata = data[i: i+ardl]
prio = uint16(ardata[0:2])
weight = uint16(ardata[2:4])
port = uint16(ardata[4:6])
ret = parseDNSstring(data[:i+ardl], i+6)
if ret:
target, j = ret
#print('SRV:', prio, weight, port, target)
adict['SRV'].append({aname: {'prio': prio, 'weight': weight, 'port': port, 'target': target}})
elif atype == TYPE_AAAA:
if ardl == 16:
ardata = data[i: i+ardl]
ip = ':'.join((hex(x) for x in ardata))
adict['AAAA'].append({aname: ip})
#print('AAAA:', {aname: ip})
else:
print('Other:', atype, data[i: i+ardl])
i += ardl
#print('ardata', ardata)
#if len(data)-i > 0:
#print("remaining Data:", data[i:])
return adict
def getUdps():
udps = usocket.socket(usocket.AF_INET, usocket.SOCK_DGRAM)
addr = usocket.getaddrinfo("0.0.0.0", 5353)[0][-1]
udps.bind(addr)
mreq = bytes([224, 0, 0, 251]) + bytes([0, 0, 0, 0])
udps.setsockopt(usocket.IPPROTO_IP, usocket.IP_ADD_MEMBERSHIP, mreq)
return udps
def service2ip(services, service):
servers = []
for s in services:
for ptr in s['PTR']:
if service in ptr:
sname = ptr[service]
for srv in s['SRV']:
if sname in srv:
host = srv[sname]['target']
port = srv[sname]['port']
for a in s['A']:
if host in a:
servers.append((a[host], port))
return servers
def test():
data = b'\x00\x00\x84\x00\x00\x00\x00\x06\x00\x00\x00\x00\x05_mqtt\x04_tcp\x05local\x00\x00\x0c\x00\x01\x00\x00\x11\x94\x00 \x1dMosquitto MQTT server on arc4\xc0\x0c\xc0(\x00\x10\x80\x01\x00\x00\x11\x94\x00\x01\x00\xc0(\x00!\x80\x01\x00\x00\x00x\x00\r\x00\x00\x00\x00\x07[\x04arc4\xc0\x17\xc0g\x00\x1c\x80\x01\x00\x00\x00x\x00\x10\xfd; \xc7u\x82\x00\x00\x8d\x99\x8e\xe8S\x91g\xc5\xc0g\x00\x1c\x80\x01\x00\x00\x00x\x00\x10\xfd; \xc7u\x82\x00\x00\x00\x00\x00\x00\x00\x00\x03\xd1\xc0g\x00\x01\x80\x01\x00\x00\x00x\x00\x04\xc0\xa8*~'
services = parsePacket(data)
print('test:', service2ip([services,], b'_mqtt._tcp.local') == [('192.168.42.126', 1883)])
def queryService(udps, service=b'_mqtt._tcp.local', timeout=1000):
try:
#udps.setblocking(True)
udps.sendto(makeServiceQuery(service), ('224.0.0.251', 5353))
#udps.setblocking(False)
services = []
starttime = utime.ticks_ms()
while utime.ticks_diff(utime.ticks_ms(), starttime) < timeout:
poller = uselect.poll()
poller.register(udps, uselect.POLLIN)
while poller.poll(100):
try:
data, addr = udps.recvfrom(1024)
print(data, addr)
s = parsePacket(data)
if s:
services.append(s)
except OSError:
# No data to evaluate
pass
except Exception as e:
import sys
sys.print_exception(e)
return service2ip(services, service)
if __name__ == '__main__':
print("start test")
test()