Cannot detect web pages on Simulator.

[ziczhu]

Hi,
We use ios-webkit-debug-proxy to do some tests on both Simulaor and Real Device.
Real Device always works well, but Simulator does not act the same on different machine.
We have 10 MacBook (pro/air/mini) , but two of them could not detect webpages when using Simulator.
The OS version is almost the same. 10.11.2/10.11.3.
Has anybody met the same problem? or give me some advices?
Thanks a lot!

[artygus]

@ziczhu make sure you have the latest iwdp version on both devices, also simulator should be started before the proxy

[ziczhu]

@artygus Thanks for quick replying. we all use the latest version(1.6) and start the simulator before the proxy, but it just didn't work.

[ziczhu]

After compared the info of port 27753, we found on some machine, there is no connection established between iwdp and 27753, and there is no webinspectord process after starting iwdp.

[artygus]

@ziczhu webinspector process should be started by a simulator, btw do you have the webinspector switch enabled in a simulator (Settings -> Safari -> Advanced -> Web Inspector)?
and what lsof -i :27753 shows?

[ziczhu]

@artygus Yes, Web Inspector had enabled.

COMMAND     PID   USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
launchd_s 65951 ziczhu    9u  IPv6 0xc4efdf170fa56525      0t0  TCP localhost:27753 (LISTEN)
launchd_s 65951 ziczhu   10u  IPv6 0xc4efdf170fa56525      0t0  TCP localhost:27753 (LISTEN)

But lsof cannot see the iwdp connecting to the 27753.
I saw the code in ios_webkit_debug_proxy.c.
Maybe in some cases, Simulator cannot start webinspector for unknown reason.

[artygus]

@ziczhu lsof output looks fine, btw I also have 10.11.3
but what sudo tcpdump -i lo0 -Xs 0 'port 27753' shows?
just to confirm, you don't see simulator there http://localhost:9221/ and nothing here http://localhost:9222/ either?

[ziczhu]

@argelius yes, we cannot see simulator on 9221/9222.
And this maybe the special case cause we try idwp on ten diferent macbooks, most of them works as expected, only two of them cannot see simulator.
By using tcpdump. I found something wired, even the process is listening on port 27753.
When iwdp wanna connect to that port. Apparently, the connection is refused by 27753.

15:10:31.879494 IP localhost.52826 > localhost.27753: Flags [S], seq 3800925964, win 65535, options [mss 16344,nop,wscale 5,nop,nop,TS val 397539194 ecr 0,sackOK,eol], length 0
        0x0000:  4500 0040 864a 4000 4006 0000 7f00 0001  E..@.J@.@.......
        0x0010:  7f00 0001 ce5a 6c69 e28d 870c 0000 0000  .....Zli........
        0x0020:  b002 ffff fe34 0000 0204 3fd8 0103 0305  .....4....?.....
        0x0030:  0101 080a 17b1 f77a 0000 0000 0402 0000  .......z........
15:10:31.879550 IP localhost.27753 > localhost.52826: Flags [R.], seq 0, ack 3800925965, win 0, length 0
        0x0000:  4500 0028 7852 4000 4006 0000 7f00 0001  E..(xR@.@.......
        0x0010:  7f00 0001 6c69 ce5a 0000 0000 e28d 870d  ....li.Z........
        0x0020:  5014 0000 fe1c 0000                      P.......

Then, i try to use python to connect to 27753, the result is the same.

In [4]: import socket
In [4]: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

In [5]: s.connect(('127.0.0.1', 27753))
---------------------------------------------------------------------------
ConnectionRefusedError                    Traceback (most recent call last)
<ipython-input-5-027930994bc9> in <module>()
----> 1 s.connect(('127.0.0.1', 27753))

ConnectionRefusedError: [Errno 61] Connection refused

Suddenly, i notice that the socket type is ipv6, then i give a try.

In [1]: import socket

In [2]: s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM, 0)                                                                                             

In [3]: s.connect(('::1', 27753, 0, 0))

It works.

16:15:07.566200 IP6 localhost.58256 > localhost.27753: Flags [S], seq 1941909515, win 65535, options [mss 16324,nop,wscale 5,nop,nop,TS val 401390220 ecr 0,s$ckOK,eol], length 0
        0x0000:  6003 39df 002c 0640 0000 0000 0000 0000  `.9..,.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 e390 6c69 73bf 300b  ..........lis.0.
        0x0030:  0000 0000 b002 ffff 0034 0000 0204 3fc4  .........4....?.
        0x0040:  0103 0305 0101 080a 17ec ba8c 0000 0000  ................
        0x0050:  0402 0000                                ....
16:15:07.566336 IP6 localhost.27753 > localhost.58256: Flags [S.], seq 3701774398, ack 1941909516, win 65535, options [mss 16324,nop,wscale 5,nop,nop,TS val $01390220 ecr 401390220,sackOK,eol], length 0
        0x0000:  600e e61e 002c 0640 0000 0000 0000 0000  `....,.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 6c69 e390 dca4 983e  ........li.....>
        0x0030:  73bf 300c b012 ffff 0034 0000 0204 3fc4  s.0......4....?.
        0x0040:  0103 0305 0101 080a 17ec ba8c 17ec ba8c  ................
        0x0050:  0402 0000  

COMMAND     PID   USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
launchd_s   825 ziczhu    8u  IPv6 0xbf8b0e1ef796ffa3      0t0  TCP localhost:27753 (LISTEN)
Python    51503 ziczhu    7u  IPv6 0xbf8b0e1efa038a83      0t0  TCP localhost:58256->localhost:27753 (ESTABLISHED)
webinspec 51591 ziczhu    5u  IPv6 0xbf8b0e1ef796ffa3      0t0  TCP localhost:27753 (LISTEN)
webinspec 51591 ziczhu    6u  IPv6 0xbf8b0e1ef796fa43      0t0  TCP localhost:27753->localhost:58256 (ESTABLISHED)

I looked into the tcpdump result on the machine which works well with idwp, I found the socket type is IPv6.

116:35:16.332998 !!!---> IP6 <---!!! localhost.57277 > localhost.27753: Flags [S], seq 1654835543, win 65535, options [mss 16324,nop,wscale 5,nop,nop,TS val 903699905 ecr 0,s
ackOK,eol], length 0
        0x0000:  600c f657 002c 0640 0000 0000 0000 0000  `..W.,.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 dfbd 6c69 62a2 c957  ..........lib..W
        0x0030:  0000 0000 b002 ffff 0034 0000 0204 3fc4  .........4....?.
        0x0040:  0103 0305 0101 080a 35dd 5dc1 0000 0000  ........5.].....
        0x0050:  0402 0000                                ....
16:35:16.333048 IP6 localhost.27753 > localhost.57277: Flags [S.], seq 1256293196, ack 1654835544, win 65535, options [mss 16324,nop,wscale 5,nop,nop,TS val 9
03699905 ecr 903699905,sackOK,eol], length 0
        0x0000:  6009 c2b5 002c 0640 0000 0000 0000 0000  `....,.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 6c69 dfbd 4ae1 834c  ........li..J..L
        0x0030:  62a2 c958 b012 ffff 0034 0000 0204 3fc4  b..X.....4....?.
        0x0040:  0103 0305 0101 080a 35dd 5dc1 35dd 5dc1  ........5.].5.].
        0x0050:  0402 0000

COMMAND    PID  USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
launchd_s  351 test2    8u  IPv6 0x66974406780bd9dd      0t0  TCP localhost:27753 (LISTEN)
ios_webki 5342 test2    8u  IPv6 0x66974406780bd47d      0t0  TCP localhost:57277->localhost:27753 (ESTABLISHED)
webinspec 5343 test2    5u  IPv6 0x66974406780bd9dd      0t0  TCP localhost:27753 (LISTEN)
webinspec 5343 test2    6u  IPv6 0x6697440678ede47d      0t0  TCP localhost:27753->localhost:57277 (ESTABLISHED)

But on my machine, u can see the socket type is IPv4, so it was failed.

15:10:31.879494 !!!--->  IP <---!!! localhost.52826 > localhost.27753: Flags [S]

I'm not an expert on network or socket programming.
But i just wonder if we need to jump from IPv4 to IPv6 to solve this problem?
Or some reason cause the socket type wrong on some machine.

Thanks a lot for replying.

[artygus]

@ziczhu ipv6 should has preference over ipv4
do you have "::1 localhost" record in /etc/hosts?

[ziczhu]

@artygus no, i haven't.
And it works after i append "::1 localhost" in /etc/hosts.
Thank u!

[artygus]

@ziczhu welcome! thanks for the report, it's surely not obvious stuff

[xudafeng]

Thanks for reporting.