Re: [lwip-users] Issue while receiving LARGE-payload on an enbedded-SOC

On Wed, Nov 29, 2017 at 4:16 PM, Ajay Garg <address@hidden> wrote:

Hi All.

We are using WolfSSL at Layer-6, and things work fine in Ubuntu-14.04 with our server.
Most importantly, the transfer of RSA-certificate from server to ubuntu works fine.

Now, when we use LWIP on an embedded-SOC, we are not able to receive the certificate.
I am going to give the details of two scenarios, but first the things that remain constant ::

a)
We are using NETCONN api for send/recv of bytes..

b)
We are using Ethernet interface,

c)
Irrespective of value of TCP_MSS, one call of recv() gives a maximum of 1460 bytes (even though the certifcate is >4000 bytes length).
Not sure if the TCP-fragmentation is happening from the server-side itself, or it's the LWIP that is "breaking" the packet.

d)
Following configurations are constant during the two scenarios

####################################################################################################

/**
* NO_SYS==1: Provides VERY minimal functionality. Otherwise,
* use lwIP facilities.
*/
#define NO_SYS                        0
#define LWIP_RAW                      0
#define LWIP_NETIF_STATUS_CALLBACK    1

/**
* SYS_LIGHTWEIGHT_PROT==1: if you want inter-task protection for certain
* critical regions during buffer allocation, deallocation and memory
* allocation and deallocation.
*/
#define SYS_LIGHTWEIGHT_PROT        1

/* These are not available when using "NO_SYS" */
#define LWIP_NETCONN                1
#define LWIP_SOCKET                 0

/* Enable DHCP support */
#define DHCP_USED

/*
   ------------------------------------
   ---------- Memory options ----------
   ------------------------------------
*/

/**
* MEM_ALIGNMENT: should be set to the alignment of the CPU
*    4 byte alignment -> #define MEM_ALIGNMENT 4
*    2 byte alignment -> #define MEM_ALIGNMENT 2
*/
#define MEM_ALIGNMENT                   4

/**
* MEMP_NUM_TCP_PCB: the number of simulatenously active TCP connections.
* (requires the LWIP_TCP option)
*/
#define MEMP_NUM_TCP_PCB                16

/**
* MEMP_NUM_TCP_PCB_LISTEN: the number of listening TCP connections.
* (requires the LWIP_TCP option)
*/
#define MEMP_NUM_TCP_PCB_LISTEN         1

/**
* MEMP_NUM_PBUF: the number of memp struct pbufs (used for PBUF_ROM and PBUF_REF).
* If the application sends a lot of data out of ROM (or other static memory),
* this should be set high.
*/
#define MEMP_NUM_PBUF                   10

/**
* MEMP_NUM_NETBUF: the number of struct netbufs.
* (only needed if you use the sequential API, like api_lib.c)
*/
#define MEMP_NUM_NETBUF                 8

/**
* MEMP_NUM_NETCONN: the number of struct netconns.
* (only needed if you use the sequential API, like api_lib.c)
*/
#define MEMP_NUM_NETCONN                16

/**
* PBUF_POOL_SIZE: the number of buffers in the pbuf pool.
*/
#define PBUF_POOL_SIZE                  10

/**
* PBUF_POOL_BUFSIZE: the size of each pbuf in the pbuf pool.
*/
#define PBUF_POOL_BUFSIZE               GMAC_FRAME_LENTGH_MAX

/*
   ----------------------------------
   ---------- DHCP options ----------
   ----------------------------------
*/

#if defined(DHCP_USED)
/**
* LWIP_DHCP==1: Enable DHCP module.
*/
#define LWIP_DHCP               1
#endif

/*
   ---------------------------------
   ---------- UDP options ----------
   ---------------------------------
*/

/**
* LWIP_UDP==1: Turn on UDP.
*/
#define LWIP_UDP                1

/*
   ---------------------------------
   ---------- TCP options ----------
   ---------------------------------
*/

/**
* LWIP_TCP==1: Turn on TCP.
*/
#define LWIP_TCP                1

/**
* TCP_WND: The size of a TCP window. This must be at least
* (2 * TCP_MSS) for things to work well
*/
#define TCP_WND                 (2 * TCP_MSS)

/**
* TCP_SND_BUF: TCP sender buffer space (bytes).
* To achieve good performance, this should be at least 2 * TCP_MSS.
*/
#define TCP_SND_BUF             (2 * TCP_MSS)

/*
   ------------------------------------
   ---------- Thread options ----------
   ------------------------------------
*/

#define netifINTERFACE_TASK_STACK_SIZE    256
#define netifINTERFACE_TASK_PRIORITY      (tskIDLE_PRIORITY + 4)
#define TCPIP_THREAD_STACKSIZE            256
#define TCPIP_THREAD_PRIO                 (tskIDLE_PRIORITY + 5)

#define TCPIP_MBOX_SIZE                   16
#define DEFAULT_ACCEPTMBOX_SIZE           16
#define DEFAULT_RAW_RECVMBOX_SIZE         16
#define DEFAULT_TCP_RECVMBOX_SIZE         16
#define DEFAULT_UDP_RECVMBOX_SIZE        16

/*
   ----------------------------------------
   ---------- Statistics options ----------
   ----------------------------------------
*/

#define LWIP_STATS 0
#define LWIP_STATS_DISPLAY 0
#define LWIP_STATS_LARGE 0

#if LWIP_STATS
#define LINK_STATS 1
#define IP_STATS   1
#define IPFRAG_STATS 0
#define ICMP_STATS 0
#define IGMP_STATS 0
#define UDP_STATS 0
#define TCP_STATS 1
#define MEM_STATS 1
#define MEMP_STATS 1
#define SYS_STATS 1
#endif

/*
   ---------------------------------------
   ---------- Debugging options ----------
   ---------------------------------------
*/

#define LWIP_NOASSERT

//#define LWIP_DEBUG
#define LWIP_DBG_MIN_LEVEL              LWIP_DBG_LEVEL_ALL
#define LWIP_DBG_TYPES_ON               LWIP_DBG_ON

#define ETHARP_DEBUG                    LWIP_DBG_OFF
#define NETIF_DEBUG                     LWIP_DBG_OFF
#define PBUF_DEBUG                      LWIP_DBG_OFF
#define API_LIB_DEBUG                   LWIP_DBG_OFF
#define API_MSG_DEBUG                   LWIP_DBG_OFF
#define SOCKETS_DEBUG                   LWIP_DBG_OFF
#define ICMP_DEBUG                      LWIP_DBG_OFF
#define IGMP_DEBUG                      LWIP_DBG_OFF
#define INET_DEBUG                      LWIP_DBG_OFF
#define IP_DEBUG                        LWIP_DBG_OFF
#define IP_REASS_DEBUG                  LWIP_DBG_OFF
#define RAW_DEBUG                       LWIP_DBG_OFF
#define MEM_DEBUG                       LWIP_DBG_OFF
#define MEMP_DEBUG                      LWIP_DBG_OFF
#define SYS_DEBUG                       LWIP_DBG_OFF
#define TIMERS_DEBUG                    LWIP_DBG_OFF
#define TCP_DEBUG                       LWIP_DBG_OFF
#define TCP_INPUT_DEBUG                 LWIP_DBG_OFF
#define TCP_FR_DEBUG                    LWIP_DBG_OFF
#define TCP_RTO_DEBUG                   LWIP_DBG_OFF
#define TCP_CWND_DEBUG                  LWIP_DBG_OFF
#define TCP_WND_DEBUG                   LWIP_DBG_OFF
#define TCP_OUTPUT_DEBUG                LWIP_DBG_OFF
#define TCP_RST_DEBUG                   LWIP_DBG_OFF
#define TCP_QLEN_DEBUG                  LWIP_DBG_OFF
#define UDP_DEBUG                       LWIP_DBG_OFF
#define TCPIP_DEBUG                     LWIP_DBG_OFF
#define PPP_DEBUG                       LWIP_DBG_OFF
#define SLIP_DEBUG                      LWIP_DBG_OFF
#define DHCP_DEBUG                      LWIP_DBG_OFF
#define AUTOIP_DEBUG                    LWIP_DBG_OFF
#define SNMP_MSG_DEBUG                  LWIP_DBG_OFF
#define SNMP_MIB_DEBUG                  LWIP_DBG_OFF
#define DNS_DEBUG                       LWIP_DBG_OFF

####################################################################################################

Now, during scenario-1, we use ::

#define TCP_MSS                 5000
#define MEM_SIZE                4 * 1024

and we receive the bytes as per the attached picture putty-cert-1.png.

In scenario-2, we use

#define TCP_MSS                 1460
#define MEM_SIZE                14 * 1024

and we receive the bytes as per the attached picture putty-cert-2.png.

Note that in case of Ubuntu, there is no continuous series of 0s, so I suspect something is wrong in my lwiopts.h configuration in our embedded-SOC case.
So, will be grateful if some light could be thrown on what parameters we need to tweak.

Thanks and Regards,
Ajay

Regards,
Ajay

From:	Ajay Garg
Subject:	Re: [lwip-users] Issue while receiving LARGE-payload on an enbedded-SOC
Date:	Wed, 29 Nov 2017 17:42:26 +0530