My Stuff: 07/01/2020

Sunday, July 5, 2020

Refoss Smart Wi-Fi Garage Door Opener

I bought an "add-on" device that will enable my garage door opener accessible via WiFi, as well as other automated processes as part of my home automation project last year. I bought it on Amazon: https://www.amazon.com/Refoss-Garage-Control-Compatible-Assistant/dp/B07PM59X4J/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

It had been working perfectly since I installed it last year, but since the last few days ago it has stopped. I thought it must be something with the networking, so I followed the procedure instructed on the manual to configure it as a new device added to the eHomeLife on my iPhone, but with no luck. The manual says, if the WiFi LED blinks rapidly, the device has been correctly set to access our home network. But, I have not been able to connect my app to the device.

Curious to see what was going on, I logged on to my AP router and could see the device had been assigned a valid IP address (192.168.1.55) and I could even ping it. That's all. I then did nmap to the device to see what ports were open. I could only see the following:

nmap -O -sO 192.168.1.55
WARNING: Disabling OS Scan (-O) as it is incompatible with the IPProto Scan (-sO)
Starting Nmap 7.80 ( https://nmap.org ) at 2020-07-05 21:44 Pacific Daylight Time
Nmap scan report for 192.168.1.55
Host is up (0.021s latency).
Not shown: 252 closed protocols
PROTOCOL STATE SERVICE
1 open icmp
6 open tcp
17 open udp
41 open|filtered ipv6
MAC Address: 48:E1:E9:51:07:50 (Chengdu Meross Technology)

Actually, if I press the WiFi button for more than 5 seconds to make it goes to configuration mode and then use the SSID of the device (it becomes an "AP" device temporarily), then open a browser to access it (at IP address 10.10.10.1, because my phone's IP was assigned 10.10.10.2), I could see basic web interface to set WIFI as well as to upgrade firmware.

Googling for "Meross" or "Refoss" firmware couldn't give anything. The company's website also doesn't give any link or information about any firmware upgrade. Also, What's the difference between "Meross" and "Refoss"? Is Refoss is a knock-off of Meross? Both are Chinese companies.

Honestly, I am now tempted to develop a similar by myself, probably using ESP32 (as using Raspberry-Pi for such thing is too much for such thing, not to consider more power-hungry).

Thursday, July 2, 2020

Mac Hash Table

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>


static unsigned char PseudoRandomHash[256] = {
     1,   87,   49,  12, 176, 178,  102, 166, 121, 193,   6,  84, 249, 230,  44,  163, 
     14, 197,  213, 181, 161,  85,  218,  80,  64, 239,  24, 226, 236, 142,  38,  200, 
    110, 177,  104, 103, 141, 253,  255,  50,  77, 101,  81,  18,  45,  96,  31,  222, 
     25, 107,  190,  70,  86, 237,  240,  34,  72, 242,  20, 214, 244, 227, 149,  235, 
     97, 234,   57,  22,  60, 250,   82,  175, 208,   5, 127, 199, 111,  62, 135,  248, 
    174, 169,  211,  58,  66, 154,  106, 195, 245, 171,  17, 187, 182, 179,   0,  243, 
    132,  56,  148,  75, 128, 133,  158, 100, 130, 126,  91,  13, 153, 246, 216,  219,
    119,  68,  223,  78,  83,  88,  201,  99, 122,  11,  92,  32, 136, 114,  52,   10, 
    138,  30,   48, 183, 156,  35,   61,  26, 143,  74, 251,  94, 129, 162,  63,  152, 
    170,   7,  115, 167, 241, 206,    3, 150,  55,  59, 151, 220,  90,  53,  23,  131, 
    125, 173,   15, 238,  79,  95,   89,  16, 105, 137, 225, 224, 217, 160,  37,  123, 
    118,  73,    2, 157,  46, 116,    9, 145, 134, 228, 207, 212, 202, 215,  69,  229, 
     27, 188,   67, 124, 168, 252,   42,   4,  29, 108,  21, 247,  19, 205,  39,  203, 
    233,  40,  186, 147, 198, 192,  155,  33, 164, 191,  98, 204, 165, 180, 117,   76, 
    140,  36,  210, 172,  41,  54,  159,   8, 185, 232, 113, 196, 231,  47, 146,  120, 
     51,  65,   28, 144, 254, 221,   93, 189, 194, 139, 112,  43,  71, 109, 184,  209}; 
     
#define N   256
     
     
int PearsonHash(uint64_t macAddr)
{
    int i;
    uint8_t h[sizeof(uint64_t)];
    int result;
    
	bzero(h, sizeof(h));
    for(i=1; i<sizeof(h); i++)
    {
		uint8_t byte = (uint8_t)(macAddr & 0xff);
        h[i] = PseudoRandomHash[(h[i-1] ^ byte) & 0xFF];
		macAddr >>= 8;
        result = h[i];
    }
    return result;
}


typedef struct
{
	uint64_t macAddr;
	int		 aid;
} RecordT;


RecordT* buildHashTable(int sz)
{
	RecordT *p = calloc(sz, sizeof(RecordT));
	return p;
}

void addRecord(RecordT* table, RecordT* rec)
{
	int slot = PearsonHash(rec->macAddr);
	table[slot].macAddr = rec->macAddr;
	table[slot].aid = rec->aid;
}

RecordT* findRecord(RecordT *table, uint64_t mac)
{
	int slot = PearsonHash(mac);
	return &table[slot];
}
     
int main()
{
    int i;
    int n;
    const uint64_t MacBase = 0x000011BABEBEEF00ULL;
    uint64_t macTable[N];
    
    for(i=0; i<N; i++)
    {
        printf(" %03u ", PseudoRandomHash[i]);
        if ((i+1)%16 == 0)
            printf("\n");
    }

	RecordT *hashTable = buildHashTable(N);

    for(i=0; i<N; i++)
    {
		uint64_t mac;
        macTable[i] = mac = MacBase + i;
	}

	for(i=0; i<N; ++i)
	{
		RecordT rec;
		rec.macAddr = macTable[i];
		rec.aid = N-i;
		addRecord(hashTable, &rec);
    }

    for(i=0; i<N; i++)
    {
        printf("%d\t %08lX: \tSlot=%u\n", i, macTable[i], PearsonHash(macTable[i]));
    }

	for(int k=0; k<N; ++k)
	{
		uint64_t mac = macTable[k];
		RecordT *p = findRecord(hashTable, mac);
    	printf("mac[%d]=%08lX \trec(%08lX,%d)\n", k, macTable[k], p->macAddr, p->aid);
	}

	free(hashTable);
}