Wednesday, December 10, 2008

Get rid of Vodafone Mobile Connect Card driver for Linux

Back in August, I explained why I switched from shipped Xandros to the Debian Eee blend. I bought my EeePC with a 3G USB modem from Huawei:

Bus 001 Device 003: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem

Thanks to Vodafone Mobile Connect Card driver for Linux, I could use it very easily. But compared to the Asus dialer, it is way slow! Between the time I click on the icon and the time I am connected, there is nearly two minutes because EeePC is not powerful enough to process quickly this bloated Python software.

While inspecting this program, you will notice that it uses wvdial behind the scene:

jlh 11626 11579 0 15:22 pts/5 00:00:00 /opt/vmc/bin/wvdial --config /tmp/VMC_uJJ0r/VMCYy5LXzwvdial.conf connect

Just copy the configuration file to wvdial.conf:

[Dialer Defaults]

Phone = *99***1#
Username = slsfr
Password = slsfr
Stupid Mode = 1
Dial Command = ATDT
Check Def Route = on
Dial Attempts = 3

[Dialer connect]

Modem = /dev/ttyUSB0
Baud = 460800
Init2 = ATZ
Init3 = ATQ0 V1 E0 S0=0 &C1 &D2 +FCLASS=0
Init4 = AT+CGDCONT=1,"IP","slsfr"
ISDN = 0
Modem Type = Analog Modem

But running wvdial with this configuration will only work if you have already entered the PIN code with Vodafone Mobile Connect Card driver for Linux. I needed to find a way to automate this. I quickly googled for a solution without luck, so I devised a way to do it myself.

What I basically did was to use strace(1) on Vodafone Mobile Connect Card driver for Linux just when I entered my PIN code. Then I looked for the PIN code itself in the output file and watched about so I could figure out the dialog with the USB modem to unlock it.

Let's say my PIN code is 5678. First check where my PIN code is used:

jlh@r2d2:~$ grep -n 5678 strace.vodafone
68172:12333 write(29, "AT+CPIN=5678\r\n"..., 14) = 14

Line 68172. The line is sent on file descriptor 29. Let's find where this file descriptor is opened before line 68172. It may be recycled during the execution of the program, so only take the last one:

jlh@r2d2:~$ cat -n strace.vodafone | head -n 68172 | grep 'open.*= 29' | tail -n 1
66643 12333 open("/dev/ttyUSB1", O_RDWR|O_NOCTTY|O_NONBLOCK|O_LARGEFILE) = 29

And where it's closed:

jlh@r2d2:~$ cat -n strace.vodafone | tail -n +66643 | grep 'close(29'
74856 12333 close(29) = 0

We just have to get read(2) and write(2) calls on file descriptor 29 between line 66643 and line 74856:

jlh@r2d2:~$ sed -n '66643,74856{ /\(read\|write\)(29/p }' strace.vodafone
12333 write(29, "AT+CSQ\r\n"..., 8) = 8
12333 read(29, "AT+CSQ\r\r\n+CME ERROR: SIM PIN requ"..., 8192) = 39
12333 write(29, "ATZ\r\n"..., 5) = 5
12333 read(29, "ATZ\r"..., 8192) = 4
12333 read(29, "\r\nOK\r\n"..., 8192) = 6
12333 write(29, "ATE0\r\n"..., 6) = 6
12333 read(29, "ATE0\r\r\nOK\r\n"..., 8192) = 11
12333 write(29, "AT+CPIN?\r\n"..., 10) = 10
12333 read(29, "\r\n+CPIN: SIM PIN\r\n\r\nOK\r\n"..., 8192) = 24
12333 read(29, "\r\n^BOOT:12633134,0,0,0,64\r\n"..., 8192) = 27
12333 write(29, "AT+CPIN=5678\r\n"..., 14) = 14
12333 read(29, "\r\nOK\r\n"..., 8192) = 6
12333 read(29, "\r\n^SIMST:1\r\n"..., 8192) = 12
12333 read(29, "\r\n^SRVST:2\r\n"..., 8192) = 12
12333 read(29, "\r\n^RSSI:13\r\n"..., 8192) = 12
12333 read(29, "\r\n^BOOT:12633134,0,0,0,64\r\n"..., 8192) = 27

The important thing is to send the PIN, so we will just stop after sending the PIN (if it doesn't work, you can still try to add a few lines). Let's translate this to a chat(8) script:

'SIM PIN required' ATZ

Then, just before running wvdial with the stolen configuration file, just use:

jlh@r2d2:~$ /usr/sbin/chat -f < /dev/ttyUSB0 > /dev/ttyUSB0

Note that if you try to rerun this chat(8) script, it won't work because the modem won't return what is expected. Given there is no way to implement branches in chat(8), I used a very small timeout so it will exit very quickly if the modem is already unlocked.