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LwIP version 1.3.0 release notes

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Note: Version 1.3.0 has been finalized and released.

Please refer to the CHANGELOG for a complete list of all changes made in version 1.3.0. The file netif/ethernetif.c provides a "good practice" example of an ethernet interface driver written for the 1.3.0 code base. The following are some particular notes and gotchas that you should be aware of if you are updating your code from 1.2.0 to 1.3.0. Bear in mind that these notes only cover the differences between 1.2.0 and 1.3.0.

  • ARP
    • New LWIP_ARP option in lwipopts.h. ARP can now be disabled completely.
    • New NETIF_FLAG_ETHARP flag for Ethernet netifs.
    • New ETHARP_TRUST_IP_MAC option in lwipopts.h. Enable this to allow any incoming IP packet to update the ARP table.
    • New LWIP_NETIF_HWADDRHINT option in lwipopts.h. Enable this to allow each pcb (i.e. connection) to maintain a cache pointing into the ARP table, instead of having to scan the whole ARP table each time.
    • ARP_QUEUEING option in lwipopts.h. Previous problems with this option have been fixed.
    • The netif_set_up function now generates a "gratuitous ARP" when the netif is brought up. Your driver should (probably) no longer need to do this.
    • etharp.c now requires a MAC address to be 6 bytes since our ARP is currently only used with Ethernet.
    • You should no longer call etharp_init in your port's initilization sequence if you use tcpip.c, because this call is done in tcpip_init function.
  • IP Fragmentation
    • New IP_FRAG_USES_STATIC_BUF option in lwipopts.h. In 1.2.0 and earlier, lwIP always used a static buffer to split packets into fragments, but now it is possible to disable this, and instead pbufs are allocated and referenced for each fragment in order to send the fragmented packet data.
  • UDP Lite
    • New LWIP_UDPLITE option in lwipopts.h. Enable UDP Lite support for all API layers.
  • ICMP
    • New LWIP_ICMP option in lwipopts.h. Enable/disable ICMP support. As with many options in lwIP, disabling this is not RFC compliant, but may not be useful depending on your application.
  • IGMP
    • New LWIP_IGMP option in lwipopts.h. Enable IGMP support for all API layers (IP_ADD_MEMBERSHIP, IP_DROP_MEMBERSHIP, IP_MULTICAST_TTL, and IP_MULTICAST_IF). A new IGMP_STATS option enables specific statistics. You have to set the NETIF_FLAG_IGMP flag for any netifs which should process IGMP messages. You also have to set MEMP_NUM_IGMP_GROUP large enough to support all needed IGMP groups.
  • SNMP
    • The default SNMP ports are now configurable at build time (using the SNMP_IN_PORT and/or SNMP_TRAP_PORT defines in lwipopts.h).
    • New NETIF_INIT_SNMP() macro to help SNMP initialization (see ethernetif.c for a sample).
    • You can define a SNMP_GET_SYSUPTIME macro in your lwipopts.h or your port to provide the system uptime information for MIB-II only when the module needs it. You can also use snmp_add_sysuptime to increase the uptime in large amounts, avoiding the need for a timer to increase the "sysuptime" every 10ms.
  • DHCP
    • New LWIP_NETIF_HOSTNAME option in lwipopts.h. Enable this to initialize a hostname field in the netif, which DHCP can then use and pass to the DHCP server to register a client hostname. You can also choose to use it for snmp_set_sysname.
  • AUTOIP
    • New LWIP_AUTOIP option in lwipopts.h. Enable AUTOIP support with or without DHCP cooperation mode (LWIP_DHCP_AUTOIP_COOP).
    • The random part for AUTOIP is done by the LWIP_AUTOIP_RAND macro. But you can redefine it in your lwipopts.h if you want to use the rand() function from the C runtime.
  • Memory Management
    • New MEM_USE_POOLS option in lwipopts.h. Enable to use memp module to avoid fragmentation problems. Need to define MEM_POOL_NUM_1/4 pool size, and MEM_POOL_SIZE_1/4 bytes size, in lwipopts.h). (FIXME: This isn't right. what option is meant here? -Jifl)
    • New MEM_LIBC_MALLOC option in lwipopts.h. Enable to use C runtime malloc in the place of mem.c.
    • New MEMP_OVERFLOW_CHECK option in lwipopts.h. Enable to add runtime checks for memory overflow (this is recommended during development).
    • New MEMCPY/SMEMCPY option in lwipopts.h. Enable to use different memory copy functions for normal (MEMCPY) and small (SMEMCPY) copies in place of the C runtime memcpy function.
    • New MEMP_NUM_TCPIP_MSG_API and MEMP_NUM_TCPIP_MSG_INPKT replace older MEMP_NUM_TCPIP_MSG.
  • System
    • New sys_mbox_tryfetch function should be implemented in your sys_arch.c. This must not block on a fetch from an mbox (see sys_arch.txt). Return SYS_MBOX_EMPTY if no message in the mbox. sys_arch_mbox_tryfetch can be implemented as a function-like macro by the port in sys_arch.h if desired.
    • New parameters for sys_thread_new function: name, and stacksize. For this last parameter, since it's system dependant, you can define xxx_THREAD_STACKSIZE macro in your lwipopts.h.
  • Network interfaces
    • The order of the argument list for etharp_output has been changed to match the order for netif->output. Please verify that your driver uses the right order if your driver uses ARP.
    • Both ARP and IP incoming packets are now passed to the tcpip_input function. This means that the payload should point to the ethhdr).
    • There are new callback features on netifs:
      • LWIP_NETIF_STATUS_CALLBACK sets a callback function to invoke when the netif status changes. For example, you can now get a callback when DHCP acquires a new IP address.
      • LWIP_NETIF_LINK_CALLBACK enables a callback that drivers should now call when the physical link status changes.
    • New NETIF_FLAG_ETHARP flag for Ethernet netifs.
    • New NETIF_FLAG_IGMP flag for IGMP netifs.
    • You should set NETIF_FLAG_LINK_UP by default for your netifs to be compatible for future uses.
    • Thread-safe functions to add/remove netif in list, and to start/stop dhcp, provided via LWIP_NETIF_API in netifapi.c.
    • New LWIP_LOOPIF_MULTITHREADING should be enabled if you use tcpip.c and the loopback interface (in loopif.c) together.
    • New PPPOE_SUPPORT option, to enable PPP over Ethernet support.
  • Raw API
    • A new tcp_output_nagle macro is available in tcp.h to allow raw API users to easily use the Nagle algorithm.
    • New pbuf_copy_partial function is now available for raw api users.
  • Sockets/Netconn API
    • Ports need to call lwip_socket_init() now for socket layer initialization (integrated in lwip_init).
    • Implementation of netconn_sendto function for netconn layer.
    • Implementation of MSG_PEEK flag for lwip_recv/recvfrom functions.
    • Implementation of SO_NO_CHECK option for UDP sockets to disable UDP checksum generation on transmit.
    • Implementation of UDP lite for sockets layer (use IPPROTO_UDPLITE for protocol in lwip_socket call, and use options UDPLITE_SEND_CSCOV/UDPLITE_RECV_CSCOV to define checksum coverage).
    • New LWIP_TCP_KEEPALIVE option in lwipopts.h. If enabled, it allows use of new socket/netconn options for TCP_KEEPIDLE/TCP_KEEPINTVL/TCP_KEEPCNT
    • New LWIP_SO_RCVTIMEO option in lwipopts.h. If enabled, it allows socket/netconn receive with timeout operations using SO_RCVTIMEO
    • New LWIP_POSIX_SOCKETS_IO_NAMES option in lwipopts.h to enable/disable POSIX-like defines names to avoid collision with some OS functions.
    • New LWIP_SOCKET & LWIP_NETCONN options in lwipopts.h. Enable to reduce footprint in some cases when these APIs are not used.
    • Improvement of lwip_recv to bypass internal netbuf boundaries in one lwip_recv call.
    • VERY IMPORTANT: There is an API breakage for netconn_addr(), since its parameters list has now changed. Your compiler should report an error if your application calls netconn_addr() with the old form of arguments, so it should not fail silently.
  • Other
    • New files to add to your makefile/project (if necessary): init.c, netbuf.c, igmp.c, autoip.c, ppp_oe.c
    • New lwip_init() function to initialize all modules. This function in directly called by tcpip_init(). lwip_init() includes some sanity checks of user-configurable values (at build time and runtime).
    • New LWIP_STATS_LARGE option, which can be enabled to get 32-bit statistics (instead of 16 bit)
    • New LWIP_UNUSED_ARG macro to avoid warnings at build time. You can override it in your cc.h if the default version is insufficient.
    • Some macros have been renamed to avoid some name collisions with some OS macros: MEM_ALIGN in LWIP_MEM_ALIGN and MEM_ALIGN_SIZE in LWIP_MEM_ALIGN_SIZE. Most of the debug macros have also been renamed: DBG_LEVEL_OFF to LWIP_DBG_LEVEL_OFF, DBG_ON to LWIP_DBG_ON, etc...
    • New LWIP_ERROR macro in debug.h. This macro can be overriden in your cc.h file to define what should be done when a fatal error is encountered. You can choose whether or not to enable this in your production release - it has lower overhead than other debug assertions and checks.
    • You should remove some obsolete definitions from your lwipopts.h file, including MEMP_NUM_API_MSG, SYS_STATS, RAW_STATS, etc... (compare with current opt.h).
    • Some limited sanity checking of user-configurable values is done in init.c. It is good practice to only rebuild init.c when you change your lwipopts.h file.
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