Ping command



  • I can not find the right way to make a ping from the GPY Pycom device to other PC connected to same router or to a page through internet. In ESP32 loaded with micropython I execute the uping library and succeeded, but I try in GPY with same code and can not.
    It appears an error :
    File "uping.py", line 30, in ping
    ImportError: no module named 'urandom'
    It seems like it doesn´t recognize "urandom"
    Is there a way to make a ping .
    Thanks



  • @robert-hh Thanks !


  • Global Moderator

    @fruiz1113 Probably it is a security setting of your PC to refuse ping requests.



  • @robert-hh

    Another question , I succedeed when I ping to external pages , and to the gateway of the router I am connected but I can not get other machines , for example router IP is 192.168.1.1 , GPY IP 192.168.1.8 , my laptop is at 192.168.1.9 , when I type uping.ping ('192.168.1.9) , I got no packets reply , may be a router set up ?
    Thanks again



  • @robert-hh said in Ping command:

    sock = usocket.socket(usocket.AF_INET, 3, 1)

    Thanks Robert ! It works ! Finally I can use the ping command to see other HW on the same network !
    It is my first step with GPY board and necessary to try network
    It is hard to find the way to use micropython ESP32 scripts compatible with pycom and there is lack of information , micropython sentences for pycom differs.
    6b139b4f-20a0-4534-94d5-d0257440bc25-image.png



  • @robert-hh understood tnx


  • Global Moderator

    @kjm This line:
    t_elasped = (utime.ticks_us()-h2.timestamp) / 1000
    Instead of utime.ticks_diff(), the code uses simple subtraction. The ticks_cpu(), ticks_us() and ticks_ms() timers wrap around, and therefore ticks_diff() must bes used for time differences. See also the documentation at https://docs.pycom.io/firmwareapi/micropython/utime.html. So the line in questions should be:
    t_elasped = utime.ticks_diff(h2.timestamp, utime.ticks_us()) / 1000

    UPDATE: since the order of arguments for ticks_diff() was changed between the master branch and the release-candidate, a safe change is:
    t_elasped = abs(utime.ticks_diff(utime.ticks_us(), h2.timestamp) / 1000)



  • @robert-hh Any ideas what could cause a large negative result?

    PING google.com (172.217.167.78): 64 data bytes
    84 bytes from 172.217.167.78: icmp_seq=1, ttl=56, time=-5859553813934326.171875 ms
    84 bytes from 172.217.167.78: icmp_seq=2, ttl=56, time=-5859553813934326.171875 ms
    84 bytes from 172.217.167.78: icmp_seq=3, ttl=56, time=-5859553813934326.171875 ms
    84 bytes from 172.217.167.78: icmp_seq=4, ttl=56, time=-5859553813934326.171875 ms
    4 packets transmitted, 4 packets received
    


  • @robert-hh said in Ping command:

    sock = usocket.socket(usocket.AF_INET, 3, 1)

    Ahh, excellent! Wish I had your flair for this stuff squire. I couldn't interest you in having a look at my other stumbling block(https://forum.pycom.io/topic/4932/urequests-timeouts/3) by any chance?


  • Global Moderator

    @kjm Try changing this line (about line 49):

    sock = usocket.socket(usocket.AF_INET, usocket.SOCK_RAW, 1)
    into
    sock = usocket.socket(usocket.AF_INET, 3, 1)

    It is just the symbolic constant usocket.SOCK_RAW, which is not defined.



  • @robert-hh Bit over my head Rob, any advice on how to get ping working on my GPY?


  • Global Moderator

    @kjm I tried that on my FiPy and it worked. Firmware 1.20.0 rc 11.1
    Otherwise I wouldn't have written that. SOCK_RAW is also not supported on ESP8266 and Pyboard D.
    Edit:
    There is this piece of code in modusocket.c:

    #if defined (LOPY) || defined (SIPY) || defined (LOPY4) || defined(FIPY)
        { MP_OBJ_NEW_QSTR(MP_QSTR_SOCK_RAW),        MP_OBJ_NEW_SMALL_INT(SOCK_RAW) },
    #endif
    

    excluding SOCK_RAW from WiPy. Dropping that #if/#endif makes ping working on the WiPy.
    Edit 2: You could try just to supply the value of 3 for the second parameter, which is the int value of usocket.SOCK_RAW.



  • @kjm Same result with

    # µPing (MicroPing) for MicroPython
    # copyright (c) 2018 Shawwwn <shawwwn1@gmail.com>
    # License: MIT
    
    # Internet Checksum Algorithm
    # Author: Olav Morken
    # https://github.com/olavmrk/python-ping/blob/master/ping.py
    # @data: bytes
    def checksum(data):
        if len(data) & 0x1: # Odd number of bytes
            data += b'\0'
        cs = 0
        for pos in range(0, len(data), 2):
            b1 = data[pos]
            b2 = data[pos + 1]
            cs += (b1 << 8) + b2
        while cs >= 0x10000:
            cs = (cs & 0xffff) + (cs >> 16)
        cs = ~cs & 0xffff
        return cs
    
    def ping(host, count=4, timeout=5000, interval=10, quiet=False, size=64):
        import utime
        import uselect
        import uctypes
        import usocket
        import ustruct
        import machine
    
        # prepare packet
        assert size >= 16, "pkt size too small"
        pkt = b'Q'*size
        pkt_desc = {
            "type": uctypes.UINT8 | 0,
            "code": uctypes.UINT8 | 1,
            "checksum": uctypes.UINT16 | 2,
            "id": uctypes.UINT16 | 4,
            "seq": uctypes.INT16 | 6,
            "timestamp": uctypes.UINT64 | 8,
        } # packet header descriptor
        h = uctypes.struct(uctypes.addressof(pkt), pkt_desc, uctypes.BIG_ENDIAN)
        h.type = 8 # ICMP_ECHO_REQUEST
        h.code = 0
        h.checksum = 0
        h.id = machine.rng() & 0xffff
        h.seq = 1
    
        # init socket
        sock = usocket.socket(usocket.AF_INET, usocket.SOCK_RAW, 1)
        sock.setblocking(0)
        sock.settimeout(timeout/1000)
        addr = usocket.getaddrinfo(host, 1)[0][-1][0] # ip address
        sock.connect((addr, 1))
        not quiet and print("PING %s (%s): %u data bytes" % (host, addr, len(pkt)))
    
        seqs = list(range(1, count+1)) # [1,2,...,count]
        c = 1
        t = 0
        n_trans = 0
        n_recv = 0
        finish = False
        while t < timeout:
            if t==interval and c<=count:
                # send packet
                h.checksum = 0
                h.seq = c
                h.timestamp = utime.ticks_us()
                h.checksum = checksum(pkt)
                if sock.send(pkt) == size:
                    n_trans += 1
                    t = 0 # reset timeout
                else:
                    seqs.remove(c)
                c += 1
    
            # recv packet
            while 1:
                socks, _, _ = uselect.select([sock], [], [], 0)
                if socks:
                    resp = socks[0].recv(4096)
                    resp_mv = memoryview(resp)
                    h2 = uctypes.struct(uctypes.addressof(resp_mv[20:]), pkt_desc, uctypes.BIG_ENDIAN)
                    # TODO: validate checksum (optional)
                    seq = h2.seq
                    if h2.type==0 and h2.id==h.id and (seq in seqs): # 0: ICMP_ECHO_REPLY
                        t_elasped = (utime.ticks_us()-h2.timestamp) / 1000
                        ttl = ustruct.unpack('!B', resp_mv[8:9])[0] # time-to-live
                        n_recv += 1
                        not quiet and print("%u bytes from %s: icmp_seq=%u, ttl=%u, time=%f ms" % (len(resp), addr, seq, ttl, t_elasped))
                        seqs.remove(seq)
                        if len(seqs) == 0:
                            finish = True
                            break
                else:
                    break
    
            if finish:
                break
    
            utime.sleep_ms(1)
            t += 1
    
        # close
        sock.close()
        ret = (n_trans, n_recv)
        not quiet and print("%u packets transmitted, %u packets received" % (n_trans, n_recv))
        return (n_trans, n_recv)
    
    


  • @robert-hh I get

    Traceback (most recent call last):
      File "<stdin>", line 114, in <module>
      File "<stdin>", line 50, in ping
    AttributeError: 'module' object has no attribute 'SOCK_RAW'
    

    when I try to run this Robert


  • Global Moderator

    @fruiz1113 Using uos.urandom, uping then is (3 lines changed):

    # µPing (MicroPing) for MicroPython
    # copyright (c) 2018 Shawwwn <shawwwn1@gmail.com>
    # License: MIT
    
    # Internet Checksum Algorithm
    # Author: Olav Morken
    # https://github.com/olavmrk/python-ping/blob/master/ping.py
    # @data: bytes
    def checksum(data):
        if len(data) & 0x1: # Odd number of bytes
            data += b'\0'
        cs = 0
        for pos in range(0, len(data), 2):
            b1 = data[pos]
            b2 = data[pos + 1]
            cs += (b1 << 8) + b2
        while cs >= 0x10000:
            cs = (cs & 0xffff) + (cs >> 16)
        cs = ~cs & 0xffff
        return cs
    
    def ping(host, count=4, timeout=5000, interval=10, quiet=False, size=64):
        import utime
        import uselect
        import uctypes
        import usocket
        import ustruct
        import uos
    
        # prepare packet
        assert size >= 16, "pkt size too small"
        pkt = b'Q'*size
        pkt_desc = {
            "type": uctypes.UINT8 | 0,
            "code": uctypes.UINT8 | 1,
            "checksum": uctypes.UINT16 | 2,
            "id": (uctypes.ARRAY | 4, 2 | uctypes.UINT8),
            "seq": uctypes.INT16 | 6,
            "timestamp": uctypes.UINT64 | 8,
        } # packet header descriptor
        h = uctypes.struct(uctypes.addressof(pkt), pkt_desc, uctypes.BIG_ENDIAN)
        h.type = 8 # ICMP_ECHO_REQUEST
        h.code = 0
        h.checksum = 0
        h.id[0:2] = uos.urandom(2)
        h.seq = 1
    
        # init socket
        sock = usocket.socket(usocket.AF_INET, usocket.SOCK_RAW, 1)
        sock.setblocking(0)
        sock.settimeout(timeout/1000)
        try:
            addr = usocket.getaddrinfo(host, 1)[0][-1][0] # ip address
        except IndexError:
            not quiet and print("Could not determine the address of", host)
            return None
        sock.connect((addr, 1))
        not quiet and print("PING %s (%s): %u data bytes" % (host, addr, len(pkt)))
    
        seqs = list(range(1, count+1)) # [1,2,...,count]
        c = 1
        t = 0
        n_trans = 0
        n_recv = 0
        finish = False
        while t < timeout:
            if t==interval and c<=count:
                # send packet
                h.checksum = 0
                h.seq = c
                h.timestamp = utime.ticks_us()
                h.checksum = checksum(pkt)
                if sock.send(pkt) == size:
                    n_trans += 1
                    t = 0 # reset timeout
                else:
                    seqs.remove(c)
                c += 1
    
            # recv packet
            while 1:
                socks, _, _ = uselect.select([sock], [], [], 0)
                if socks:
                    resp = socks[0].recv(4096)
                    resp_mv = memoryview(resp)
                    h2 = uctypes.struct(uctypes.addressof(resp_mv[20:]), pkt_desc, uctypes.BIG_ENDIAN)
                    # TODO: validate checksum (optional)
                    seq = h2.seq
                    if h2.type==0 and h2.id==h.id and (seq in seqs): # 0: ICMP_ECHO_REPLY
                        t_elasped = (utime.ticks_us()-h2.timestamp) / 1000
                        ttl = ustruct.unpack('!B', resp_mv[8:9])[0] # time-to-live
                        n_recv += 1
                        not quiet and print("%u bytes from %s: icmp_seq=%u, ttl=%u, time=%f ms" % (len(resp), addr, seq, ttl, t_elasped))
                        seqs.remove(seq)
                        if len(seqs) == 0:
                            finish = True
                            break
                else:
                    break
    
            if finish:
                break
    
            utime.sleep_ms(1)
            t += 1
    
        # close
        sock.close()
        ret = (n_trans, n_recv)
        not quiet and print("%u packets transmitted, %u packets received" % (n_trans, n_recv))
        return (n_trans, n_recv)
    

    Edit: Added a useful error message in case the address could not be resolved.


  • Global Moderator

    @fruiz1113 replace in line 30:
    import urandom
    by
    import machine

    and in line ~46

    h.id = urandom.randint(0, 65535)
    by
    h.id = machine.rng() & 0xffff
    Then it works. You can also use uos.urandom, but that returns a byte array, which then has to be converted to an int, which then will by converted back to 2 byte data, .... But uos.urandom() exists in both platforms, so it might be the better choice.
    Yes, the differences in libraries are quite an obstacle, but you can deal with it.



  • Sympathies fruiz. I tried for ages to modify uping to work with pycom's particular flavour of micropython but no luck. One of the sad realities of life is that each micopython implementation chooses which subset of python to support & it's all too common for code that runs on a regular ESP32 to stall on a Pycom device. Ping is a great deal to verify connectivity
    & I miss it heaps!


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