The uIP embedded TCP/IP stack ()

Primoz Lemut | 2 Nov 2011 22:34

uIP connect issue

Dear all,

I hope this mailing list is still active. I am a new uIP user.

I am working on a simple application running on ATmega328. The embedded 
device should made a TCP connection to the server and first send it a 
communication configuration IP packet. Afterwards the server is 
continuously sending the packet and the embedded device should be only 
properly decoding them.

Unfortunately everything stopped right at the beginning when I attempt 
to connect to the server. For debugging the network traffic I am using 
the Wireshark. Even if the connection is not successful I can still ping 
the embedded device after the connect attempt.

For the reference code I took the microwebserver application 
(http://en.klinkerstein.m-faq.de/index.php/MicroWebServer), that 
compiles nicely using the AVRstudio. The webserver is running really well.

The connection I attempt to perform as suggested in the manual and in 
all examples:

     uip_ipaddr(&VCaddr, 192,168,10,20);
     conn = uip_connect(&VCaddr, HTONS(5005));

Tracking the activity with Wireshark I noticed that instead of 5 or 6 
steps in typical connection sequence there are only 3. And those 3 are 
very different from what they are supposed to be. I attaching two images 
showing Wireshark capture for proper and false connection sequence.

(Continue reading)

headers

Thierry Didi | 5 Oct 2011 22:44

can uip receive multiple segments in a raw of size smaller than MSS ?

Hello,

I am writing an ftp client based on uip (and Contiki). I have the following issue:

- I have set MSS to 536 (in contiki-conf.h).

- When the exchange of ftp control messages is over (i.e. TCP port 21), and the data connection is opened, the server starts sending the file.

- But, instead of putting the first data packet in a TCP segment of size 536, it splits it in 2 TCP segments of size 268 = 536/2.

- Its sends both segments in a raw, without waiting for the acknowledgement of the first TCP segment.

- But my ftp client (and uip) sends an ACK for the first one, while the ftp server is waiting for an ACK for the second segment only, generating a lot of retransmissions (seen on tcpdump).

- Furthermore, it’s a waste of RAM since I have allocated a 536 bytes uip_buffer for receiving packets of only 268 bytes …

So, I have the following question:

- Is uip capable of receiving a data stream from a server which sends multiple TCP segment without waiting an ACK for each segment ? Is there something special to do ?

- If not, is it possible to configure an ftp server (or a linux IP stack) so that is always use the maximum MSS for data packets instead splitting packets in segments smaller than the MSS size ?

Thanks,

Thierry

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jbsnyder | 29 Sep 2011 20:28

Copy of uip patched repository?

Hi -

After running into some issues with uIP, I stumbled upon some messages noting
that a git repo had been created (http://gitweb.aeruder.net/?p=uip.git) for
keeping patches together that had been floating around on the list over the
years since the uip-1.0 release.  I was interested in taking advantage of this,
but I'm finding that the gitweb and git server on the appropriate hosts
provided by Andrew aren't currently working.  I have contacted him separately,
but I'm wondering if anyone might have a clone of this repo around that I could
grab?  I can find various derivative codebases that seem like they've
integrated some of these patches, but some of them have changed layouts or made
other modifications so I'd like things as close to the plain distribution as
possible.

Best.

-jsnyder

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Edgardo C. | 15 Jul 2011 17:18

UDP custom packets

Hello guys,

I really need your help. I have an application on a board that receive "echo" UDP packets (one each 5'') from a computer and response back with replays, and it works perfectly. The "echo" packets has the same meaning like, ... are you there?

The thing is that once I receive the first "echo" UDP packet, I want to send data UDP packets back to the computer, continuously.

And this is my problem ... read on

In the ethernet.c file I have this

uip_len = tapdev_read(uip_buf);

if(uip_len > 0)

inside the famous while loop (as you know). So, basically, it checks for new data and if so, process it, otherwise, check the timers.

Inside my application that manage the response to the "echo" I have this:

void udp_init(void)

{

uip_ipaddr_t addr;

struct uip_udp_conn *c;

uip_ipaddr(&addr, 192,168,0,113);

c = uip_udp_new(&addr, HTONS(15000));

if(c != NULL) {

uip_udp_bind(c, HTONS(15001));

}

what I have to do is put something in the while loop to send the data packets (based on a flag) continuously, after receiving receiving the first "echo" packet. So, I need to customize the UDP packet. I tried to copy the previously received uip_buf in a temp variable and packets are send out, but malformed. I put the memcpy, set the uip_len, ecc. but it still does not work. Hope you can help me.

Thanks in advance,

Regards,

headers

Bhushan Talele | 8 Jul 2011 13:38

fsdata.c generator not working

I am currently working on a project based on the Olimex board LPC-E2124.

As per the information on the main page of uIP I downloaded the fs_generator.zip which is used to generate the file fsdata.c
The executable inside the zip file doesn't seem to work on my PC. It gives an error that some root directory is not proper or something of that sort.

Is this because of my system not being compatible with the program provided? If yes, then is there an alternative, solution to this issue?

The system that I use is running windows 7, 64 bit OS.

Thanks in advance,
Bhushan.

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Edgardo C. | 27 Jun 2011 21:26

Re: UDP problems with IP header

Hello Peter and Martin,

Sorry I did not replay earlier, I am not at work now, So, tomorrow I'll check all you mentioned in the mails. The IP configuration is right, I checked it twice.

This is the first time I use uIP, and I use it in Linux before installing it into the controller board. You are right, I checked uip.c and indeed, uIP drops the ip headers !=0x45. I send the UDP datagrams rom a QT application, so if uIP drop long ip headers, it means that I am not able to use uIP, what's a pity.

I use uIP 1.0.

Now I remember that the first time i downloaded uIP, I compile it in Ubuntu ( my linux machine) with the httpd and I tried accessing the web server from the browser and it worked, I could access to the html pages, so, it means that something happens afterwards. I'll let you know tomorrow. Thanks in advance guys for the support,

Regards,

2011/6/27 Peter Zuidema <pzuidema <at> opencontroller.com>

Hello Edgardo,

Martin is right about that 0x46 is possible in the IP header, but it is not supported by uIP v1.0

So there is probably some service or device on your network using longer headers. uIP just ignores them (drop).

Maybe try using netcat on your linux machine to send controlled UDP packets to your uIP application (replace IP address with the one uIP is using):
$ netcat -u -p 9988 192.168.8.8 1167
Type 'Hello' with Enter

Did you also try to run it on your microcontroller? Also test via ICMP and try to ping the uIP device (or application). If this all fails you have to trace the packets and see what is exactly received by the uIP stack.

I presume you have configured all the network stuff right? Like a valid MAC address (uip_ethaddr), IP-address (uip_hostaddr), Netmask (uip_netmask) and Default Router address (uip_draddr).

Regards,
Peter

On 27-6-2011 18:03, Martin Maurer wrote:

Hello,

have you tried to do a wireshark trace ? Do you see the error in wireshark ? Can you post the trace or content of the "broken" packet ?

If i remember correctly, 0x46 (and higher) instead of 0x45 is possible. It means IP uses additional headers, so IP hdr is not 20 bytes (5 * 4 bytes) but 24 bytes (6 * 4 bytes) long.

http://www.networksorcery.com/enp/protocol/ip.htm

http://www.networksorcery.com/enp/protocol/ip.htm#Options

BTW: What uip version do you use ? 0.9 or 1.0 ?

Best regards,

Martin

----- Original Message -----

From: Edgardo C.

To: Peter Zuidema

Cc: uip-users <at> sics.se

Sent: Monday, June 27, 2011 5:36 PM

Subject: Re: [uip-users] UDP problems with IP header

Hello Peter,

First of all, let me say that I am compiling both, the uip UDP application and the pc application on a Linux pc. So, the application that send the UDP datagrams is a GUI application running on the Linux machine where the uip run as well. So, both application run on the same machine.

I removed the uip_listen and the problem persist. I do not receive any packet and what is weird is that even though I don't send any packet from the application, as soon as I run the uip UDP aplication, it gives me the error. I tried compiling the httpd application that comes into the uip package and I get the same error. agrrrrrrrrrrrrrrrrrrrrr

I have no idea.

2011/6/27 Peter Zuidema <pzuidema <at> opencontroller.com>
Hello Edgardo,

Remove the uip_listen() call because this is only for TCP.

Do you receive nothing at all (the 1st Hello), or do you see the error after waiting for response after send_request()?

In the last case, try resetting the newdata flag directly after send_request().

Regards,
Peter

headers

Edgardo C. | 27 Jun 2011 17:36

Re: UDP problems with IP header

Hello Peter,

First of all, let me say that I am compiling both, the uip UDP application and the pc application on a Linux pc. So, the application that send the UDP datagrams is a GUI application running on the Linux machine where the uip run as well. So, both application run on the same machine.

I removed the uip_listen and the problem persist. I do not receive any packet and what is weird is that even though I don't send any packet from the application, as soon as I run the uip UDP aplication, it gives me the error. I tried compiling the httpd application that comes into the uip package and I get the same error. agrrrrrrrrrrrrrrrrrrrrr

I have no idea.

2011/6/27 Peter Zuidema <pzuidema <at> opencontroller.com>

Hello Edgardo,

Remove the uip_listen() call because this is only for TCP.

Do you receive nothing at all (the 1st Hello), or do you see the error after waiting for response after send_request()?

In the last case, try resetting the newdata flag directly after send_request().

Regards,
Peter

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Edgardo C. | 27 Jun 2011 15:28

UDP problems with IP header

Hello again,

I have a problem with my UDP application. When I send UDP packets from my pc, I get the following error in uIP:

"invalid version or header length" and using a log I can see that it is 0x46 and not 0x45 as expected for IPV4. IPV6 is disabled in my Linux pc and there are no macros in uIP enabling it. Any idea how to solve it? thx in advance,

Regards,

headers

Edgardo C. | 24 Jun 2011 09:22

UDP connection

Hello,

Could somebody point me an example of sending and receiving simple UDP packets with uIP?. I want to establish a UDP communication between a computer and a PCB.
Thanks in advance,

headers

Martin Maurer | 10 May 2011 14:38

Retransmission and uip_split - is this working and how is it working ?

Hello,

i have a question regarding uip 1.0 / Retransmission / uip_split:

I am using uip 1.0 and uip_split on an embedded system. From time to time i get a retransmission signaled by uip.

Analyzing some wireshark traces, i see that a single packet which is sent by my app is correctly cut into 2 pieces by uip_split,

but then sometimes (i think normal behaviour) one of the two or both packets must be transmitted.

How do you do this correctly ? Is it just enough to call uip_send of the previous packet ?

Or must there be some additional implementation / some checks, which part (or both) must be retransmitted ?

When i always send the big application packet a second time, does uip (or uip_split) handle the sequence counters which

must now fit to the first / second smaller part of big packet ?

When i have multiple connections, must a keep the last sent packet of each connection till i receive the ACK on the given connection ?

Is this correct ?

Many thanks for clarifying !

Best regards,

Martin

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Dan Pomohaci | 2 May 2011 09:12

port for OMAP-L138

Hi,

Does anyone know if there is a port of uIP for the  OMAP-L138
(ARM926EJ-S) processor?

Thanks,
dpom

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