lwIP  2.0.2
Lightweight IP stack
This file lists major changes between release versions that require
ports or applications to be changed. Use it to update a port or an
application written for an older version of lwIP to correctly work
with newer versions.

(git master)

  * [Enter new changes just after this line - do not remove this line]


  ++ Application changes:

  * UDP does NOT receive multicast traffic from ALL netifs on an UDP PCB bound to a specific
    netif any more. Users need to bind to IP_ADDR_ANY to receive multicast traffic and compare 
    ip_current_netif() to the desired netif for every packet.
    See bug #49662 for an explanation.


  ++ Application changes:

  * Changed netif "up" flag handling to be an administrative flag (as opposed to the previous meaning of
    "ip4-address-valid", a netif will now not be used for transmission if not up) -> even a DHCP netif
    has to be set "up" before starting the DHCP client
  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
  * Changed ip_addr_t to be a union in dual-stack mode (use ip4_addr_t where referring to IPv4 only).
  * Major rewrite of SNMP (added MIB parser that creates code stubs for custom MIBs);
    supports SNMPv2c (experimental v3 support)
  * Moved some core applications from contrib repository to src/apps (and include/lwip/apps)

  +++ Raw API:
    * Changed TCP listen backlog: removed tcp_accepted(), added the function pair tcp_backlog_delayed()/
      tcp_backlog_accepted() to explicitly delay backlog handling on a connection pcb

  +++ Socket API:
    * Added an implementation for posix sendmsg()
    * Added LWIP_FIONREAD_LINUXMODE that makes ioctl/FIONREAD return the size of the next pending datagram

  ++ Port changes

  +++ new files:
    * MANY new and moved files! 
    * Added src/Filelists.mk for use in Makefile projects
    * Continued moving stack-internal parts from abc.h to abc_priv.h in sub-folder "priv"
      to let abc.h only contain the actual application programmer's API

  +++ sys layer:
    * Made LWIP_TCPIP_CORE_LOCKING==1 the default as it usually performs better than
      the traditional message passing (although with LWIP_COMPAT_MUTEX you are still
      open to priority inversion, so this is not recommended any more)
    * Added LWIP_NETCONN_SEM_PER_THREAD to use one "op_completed" semaphore per thread
      instead of using one per netconn (these semaphores are used even with core locking
      enabled as some longer lasting functions like big writes still need to delay)
    * Added generalized abstraction for itoa(), strnicmp(), stricmp() and strnstr()
      in def.h (to be overridden in cc.h) instead of config 
      options for netbiosns, httpd, dns, etc. ...
    * New abstraction for hton* and ntoh* functions in def.h.
      To override them, use the following in cc.h: 
      #define lwip_htons(x) <your_htons>
      #define lwip_htonl(x) <your_htonl>

  +++ new options:
     * TODO

  +++ new pools:
     * Added LWIP_MEMPOOL_* (declare/init/alloc/free) to declare private memp pools
       that share memp.c code but do not have to be made global via lwippools.h
     * Added pools for IPv6, MPU_COMPATIBLE, dns-api, netif-api, etc.
     * added hook LWIP_HOOK_MEMP_AVAILABLE() to get informed when a memp pool was empty and an item
       is now available

  * Signature of LWIP_HOOK_VLAN_SET macro was changed

  * LWIP_DECLARE_MEMORY_ALIGNED() may be used to declare aligned memory buffers (mem/memp)
    or to move buffers to dedicated memory using compiler attributes

  * Standard C headers are used to define sized types and printf formatters
    (disable by setting LWIP_NO_STDINT_H=1 or LWIP_NO_INTTYPES_H=1 if your compiler
    does not support these)

  ++ Major bugfixes/improvements

  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
  * Major rewrite of PPP (incl. keep-up with apache pppd)
    see doc/ppp.txt for an upgrading how-to
  * Major rewrite of SNMP (incl. MIB parser)
  * Fixed timing issues that might have lead to losing a DHCP lease
  * Made rx processing path more robust against crafted errors
  * TCP window scaling support
  * modification of api modules to support FreeRTOS-MPU (don't pass stack-pointers to other threads)
  * made DNS client more robust
  * support PBUF_REF for RX packets
  * LWIP_NETCONN_FULLDUPLEX allows netconn/sockets to be used for reading/writing from separate
    threads each (needs LWIP_NETCONN_SEM_PER_THREAD)
  * Moved and reordered stats (mainly memp/mib2)


  ++ Application changes:

  * Replaced struct ip_addr by typedef ip_addr_t (struct ip_addr is kept for
    compatibility to old applications, but will be removed in the future).

  * Renamed mem_realloc() to mem_trim() to prevent confusion with realloc()

  +++ Raw API:
    * Changed the semantics of tcp_close() (since it was rather a
      shutdown before): Now the application does *NOT* get any calls to the recv
      callback (aside from NULL/closed) after calling tcp_close()

    * When calling tcp_abort() from a raw API TCP callback function,
      make sure you return ERR_ABRT to prevent accessing unallocated memory.
      (ERR_ABRT now means the applicaiton has called tcp_abort!)

  +++ Netconn API:
    * Changed netconn_receive() and netconn_accept() to return
      err_t, not a pointer to new data/netconn.

  +++ Socket API:
    * LWIP_SO_RCVTIMEO: when accept() or recv() time out, they
      now set errno to EWOULDBLOCK/EAGAIN, not ETIMEDOUT.

    * Added a minimal version of posix fctl() to have a
      standardised way to set O_NONBLOCK for nonblocking sockets.

  +++ all APIs:
    * correctly implemented SO(F)_REUSEADDR

  ++ Port changes

  +++ new files:

    * Added 4 new files: def.c, timers.c, timers.h, tcp_impl.h:

    * Moved stack-internal parts of tcp.h to tcp_impl.h, tcp.h now only contains
      the actual application programmer's API
    * Separated timer implementation from sys.h/.c, moved to timers.h/.c;
      Added timer implementation for NO_SYS==1, set NO_SYS_NO_TIMERS==1 if you
      still want to use your own timer implementation for NO_SYS==0 (as before).

  +++ sys layer:

    * Converted mbox- and semaphore-functions to take pointers to sys_mbox_t/

    * Converted sys_mbox_new/sys_sem_new to take pointers and return err_t;

    * Added Mutex concept in sys_arch (define LWIP_COMPAT_MUTEX to let sys.h use
      binary semaphores instead of mutexes - as before)

  +++ new options:

     * Don't waste memory when chaining segments, added option TCP_OVERSIZE to
       prevent creating many small pbufs when calling tcp_write with many small
       blocks of data. Instead, pbufs are allocated larger than needed and the
       space is used for later calls to tcp_write.

     * Added LWIP_NETIF_TX_SINGLE_PBUF to always copy to try to create single pbufs
       in tcp_write/udp_send.

    * Added an additional option LWIP_ETHERNET to support ethernet without ARP
      (necessary for pure PPPoE)

    * Add MEMP_SEPARATE_POOLS to place memory pools in separate arrays. This may
      be used to place these pools into user-defined memory by using external

    * Added TCP_SNDQUEUELOWAT corresponding to TCP_SNDLOWAT

  +++ new pools:

     * Netdb uses a memp pool for allocating memory when getaddrinfo() is called,
       so MEMP_NUM_NETDB has to be set accordingly.

     * DNS_LOCAL_HOSTLIST_IS_DYNAMIC uses a memp pool instead of the heap, so
       MEMP_NUM_LOCALHOSTLIST has to be set accordingly.

     * Snmp-agent uses a memp pools instead of the heap, so MEMP_NUM_SNMP_* have
       to be set accordingly.

     * PPPoE uses a MEMP pool instead of the heap, so MEMP_NUM_PPPOE_INTERFACES
       has to be set accordingly

  * Integrated loopif into netif.c - loopif does not have to be created by the
    port any more, just define LWIP_HAVE_LOOPIF to 1.

  * Added define LWIP_RAND() for lwip-wide randomization (needs to be defined
    in cc.h, e.g. used by igmp)

  * Added printf-formatter X8_F to printf u8_t as hex

  * The heap now may be moved to user-defined memory by defining
    LWIP_RAM_HEAP_POINTER as a void pointer to that memory's address

  * added autoip_set_struct() and dhcp_set_struct() to let autoip and dhcp work
    with user-allocated structs instead of calling mem_malloc

  * Added const char* name to mem- and memp-stats for easier debugging.

  * Calculate the TCP/UDP checksum while copying to only fetch data once:
    Define LWIP_CHKSUM_COPY to a memcpy-like function that returns the checksum

  * Added SO_REUSE_RXTOALL to pass received UDP broadcast/multicast packets to
    more than one pcb.

  * Changed the semantics of ARP_QUEUEING==0: ARP_QUEUEING now cannot be turned
    off any more, if this is set to 0, only one packet (the most recent one) is
    queued (like demanded by RFC 1122).

  ++ Major bugfixes/improvements

  * Implemented tcp_shutdown() to only shut down one end of a connection
  * Implemented shutdown() at socket- and netconn-level
  * Added errorset support to select() + improved select speed overhead
  * Merged pppd to v2.3.11 (including some backported bugfixes from 2.4.x)
  * Added timer implementation for NO_SYS==1 (may be disabled with NO_SYS_NO_TIMERS==1
  * Use macros defined in ip_addr.h to work with IP addresses
  * Implemented many nonblocking socket/netconn functions
  * Fixed ARP input processing: only add a new entry if a request was directed as us
  * mem_realloc() to mem_trim() to prevent confusion with realloc()
  * Some improvements for AutoIP (don't route/forward link-local addresses, don't break
    existing connections when assigning a routable address)
  * Correctly handle remote side overrunning our rcv_wnd in ooseq case
  * Removed packing from ip_addr_t, the packed version is now only used in protocol headers
  * Corrected PBUF_POOL_BUFSIZE for ports where ETH_PAD_SIZE > 0
  * Added support for static ARP table entries


  * initial version of this file