Socket API "send" hangs when sending multiple TCP messages

[Omer Farooq]

Hi, 

   I am developing an application that requires communication between two nrf52840-based devices. There is a scenario in my application where the devices needs to exchange multiple TCP packets, however after transmitting nearly 50 messages, send API hangs. The inter-message transmission interval is 70-200 ms. I am using TCP over IEEE 802.15.4 with POSIX names enabled. My application's message size 14-byte. I would be really thankful for your help. 

Best regards,

Omer

[Carl Richard]

Hello, Omer!

Are you able to provide any logs from the devices? I would also like information about which code your samples are based on, and whether you are using the nRF Connect SDK or the nRF5 SDK.

Best regards,
Carl Richard

[Omer Farooq]

Hi Carl, 

    Regarding logs - I am obtaining information by using printk and displaying the information on terminal. I am relatively new to Zephyr, therefore I do not know whether Zephyr stores some log files. If so, I would really appreciate if you could also tell me where those log files are stored. 

   Code Sample: I built my code using the socket client server example available at zephyr/samples/net/sockets. 

   I am using nRf Connect SDK. 

Best regards,

Omer

[Carl Richard]

Hi again!

Understood. Could you add the following to your prj.conf and share any eventual output with me?

CONFIG_ASSERT=y
CONFIG_SERIAL=y

CONFIG_LOG=y
CONFIG_LOG_IMMEDIATE=y
CONFIG_LOG_BACKEND_SHOW_COLOR=n

CONFIG_NET_LOG=y

#CONFIG_NET_IF_LOG_LEVEL_DBG=y
#CONFIG_NET_L2_ETHERNET_LOG_LEVEL_DBG=y

CONFIG_NET_SOCKETS_LOG_LEVEL_DBG=y
CONFIG_NET_CONN_LOG_LEVEL_DBG=y
CONFIG_NET_CONTEXT_LOG_LEVEL_DBG=y

CONFIG_NET_TCP_LOG_LEVEL_DBG=y

Best regards,
Carl Richard

[Omer Farooq]

Hi Carl, 

   Thanks for the reply. I did add the CONFIGs to my proj.conf files for the client and the server applications. My application works the following way.

    - Once a user presses button 3 on nrf52840 dk the communication starts, however as we now have CONFIG_ASSERT=y in the proj.conf file, my application resets when I press the button on the client application please see attached screenshot. This does not happen for the server application. 

If I remove CONFIG_ASSERT=y, the above does not happen. In order to reproduce the erroneous scenario, I removed the assert config, and execute the client server applications. Please see attached logs. You can see at the end of the logs server application requested data, client did send the data,  however server is stuck.  serverlog.txtclientlog.txt

[Omer Farooq]

Client log.

1055.clientlog.txt

[Carl Richard]

Thanks for the logs! I couldn't manage to find any obvious problems in them. Could you share the applications here so that I can have a look?

This could possible be an overflow issue. Does it happen after the same number of messages every time?

Best regards,
Carl Richard

[Omer Farooq]

Thanks for your reply. Unfortunately, I will not be able to share my application code here due to restrictions.

The problem nearly starts to happen after the same number of messages, but the number is not exactly the same very time. Can I suggest you to please use net/sockets echo client server example and transmit messages in an loop, you may reproduce the same problem?

Best regards,

Omer

[Omer Farooq]

Hi Carl, 

   I have tested echo-client/server example by transmitting data packets in a loop. I can now confirm that the blocking behavior is reproduced in the echo-client/server example as well. I have attached the source files and proj.conf file. Please note that I am using nRF Connect SDK Version 1.3.0, however I have also tested on over nRF Connect Version 1.5.0.  6472.prj.conf

Fullscreen echo-client.c Download

#include <zephyr.h>
#include <errno.h>
#include <stdio.h>

#include <net/socket.h>
#include <linker/sections.h>
#include <shell/shell.h>
#include <net/net_core.h>

#define MY_PORT 4242
#define PEER_PORT 4242

void main()
{
    printk("Starting the Process ... \n") ; 
	struct sockaddr_in6 addr6, addr_peer;
	int sock_id = 0 ; 
	int ret = 0 ;  
	char msg[] = "HELLO\n" ; 
    char msg1[100] ; 
	
	memset(&addr6, 0, sizeof(addr6));
	addr6.sin6_family = AF_INET6;
	addr6.sin6_port = htons(MY_PORT);
	inet_pton(AF_INET6, CONFIG_NET_CONFIG_MY_IPV6_ADDR,
			  &addr6.sin6_addr);
	sock_id = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
	if(sock_id == -1)
	{
		printk("Error in creating socket \n") ; 
		return ; 
	}
	
	ret = bind(sock_id, (struct sockaddr *) &addr6, sizeof(addr6)) ; 
	
	if(ret < 0)
	{
			printk("Error in Binding the Socket \n") ; 
			return ; 
	}
	while(true)
	{
		(void) memset(&addr_peer, 0, sizeof(addr_peer)); 
		addr_peer.sin6_family = AF_INET6;
		addr_peer.sin6_port = htons(PEER_PORT);
		inet_pton(AF_INET6, CONFIG_NET_CONFIG_PEER_IPV6_ADDR,
			  &addr_peer.sin6_addr);
        ret = sendto(sock_id, msg, sizeof(msg), 0, (struct sockaddr *)&addr_peer, sizeof(addr_peer)) ;
		if(ret < 0)
		{
			printk("Error in Transmitting the Message \n"); 
			return ; 
		}
		else
		{
			printk("The message has been transmitted \n") ;
			ret = recv(sock_id, (void*) msg1, sizeof(msg1), 0) ;
			printk("%s\n" ,msg) ; 
			/*stop_time = k_cycle_get_32();
			cycles_spent = stop_time - start_time;
			nanoseconds_spent = k_cyc_to_ns_ceil32(cycles_spent) ; //SYS_CLOCK_HW_CYCLES_TO_NS(cycles_spent);*/
		}
		memset(msg1, sizeof(msg1), 0) ; 
		k_msleep(1000) ;
	}
	return ; 
}

Fullscreen echo-server.c Download

#include <zephyr.h>
#include <errno.h>
#include <stdio.h>

#include <net/socket.h>
#include <linker/sections.h>
#include <shell/shell.h>
#include <net/net_core.h>

#define MY_PORT 4242
#define PEER_PORT 4242

void main()
{
	struct sockaddr_in6 addr6, addr_peer;
	int sock_id = 0 ; 
	int ret = 0 ;  
	char msg[100] ; 

	(void)memset(&addr6, 0, sizeof(addr6));
	addr6.sin6_family = AF_INET6;
	addr6.sin6_port = htons(MY_PORT);
	inet_pton(AF_INET6, CONFIG_NET_CONFIG_MY_IPV6_ADDR,
			  &addr6.sin6_addr);
	sock_id = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
	if(sock_id == -1)
	{
		printk("Error in creating socket \n") ; 
		return ; 
	}
	
	ret = bind(sock_id, (struct sockaddr *) &addr6, sizeof(addr6)) ;
        addr_peer.sin6_family = AF_INET6;
        addr_peer.sin6_port = htons(PEER_PORT);
        inet_pton(AF_INET6, CONFIG_NET_CONFIG_PEER_IPV6_ADDR,
                  &addr_peer.sin6_addr);
	
	while(true)
	{ 
		/* Continously send message to a server after every 5 seconds */
		ret = recv(sock_id, (void*) msg, sizeof(msg), 0) ; 
		if(ret < 0)
		{
			printk("Error in Receiving a Message \n"); 
			return ; 
		}
		else
		{
			printk("%s\n", msg) ; 
			ret = sendto(sock_id, msg, sizeof(msg), 0, (struct sockaddr *)&addr_peer, sizeof(addr_peer)) ;
			if(ret < 0 )
			{
					printk("Error in transmitting message \n") ; 
			}
		}
	}
	close(sock_id) ; 
	return ; 
}