FUTURE

  * TODO: The lwIP source code makes some invalid assumptions on processor
    word-length, storage sizes and alignment. See the mailing lists for
    problems with exoteric (/DSP) architectures showing these problems.
    We still have to fix some of these issues neatly.

  * TODO: the ARP layer is not protected against concurrent access. If
    you run from a multitasking OS, serialize access to ARP (called from
    your network device driver and from a timeout thread.)

  * TODO: the PPP code is broken in a few ways. There are namespace
    collisions on BSD systems and many assumptions on word-length
    (sizeof(int)). In ppp.c an assumption is made on the availability of
    a thread subsystem. Either PPP needs to be moved to contrib/ports/???
    or rearranged to be more generic.
    
  * TODO: review the the sequential netconn and socket API (lwip/src/api)
    for bugs and performance issues. Frequent system calls (e.g. sys_mbox_fetch)
    slooow things down considerably. 

HISTORY

(CVS HEAD)

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

  ++ New features:

  2006-12-01 Christiaan Simons
  * mem.h, opt.h: Added MEM_LIBC_MALLOC option.
    Note this is a workaround. Currently I have no other options left.

  2006-10-26 Christiaan Simons (accepted patch by Jonathan Larmour)
  * ipv4/ip_frag.c: rename MAX_MTU to IP_FRAG_MAX_MTU and move define
    to include/lwip/opt.h.
  * ipv4/lwip/ip_frag.h: Remove unused IP_REASS_INTERVAL.
    Move IP_REASS_MAXAGE and IP_REASS_BUFSIZE to include/lwip/opt.h.
  * opt.h: Add above new options.

  2006-08-18 Christiaan Simons
  * tcp_{in,out}.c: added SNMP counters.
  * ipv4/ip.c: added SNMP counters.
  * ipv4/ip_frag.c: added SNMP counters.

  2006-08-08 Christiaan Simons
  * etharp.{c,h}: added etharp_find_addr() to read
    (stable) ethernet/IP address pair from ARP table
  
  2006-07-14 Christiaan Simons
  * mib_structs.c: added
  * include/lwip/snmp_structs.h: added
  * netif.{c,h}, netif/ethernetif.c: added SNMP statistics to netif struct

  2006-07-06 Christiaan Simons
  * snmp/asn1_{enc,dec}.c added
  * snmp/mib2.c added
  * snmp/msg_{in,out}.c added
  * include/lwip/snmp_asn1.h added
  * include/lwip/snmp_msg.h added
  * doc/snmp_agent.txt added  

  2006-03-29 Christiaan Simons
  * inet.c, inet.h: Added platform byteswap support.
    Added LWIP_PLATFORM_BYTESWAP define (defaults to 0) and
    optional LWIP_PLATFORM_HTONS(), LWIP_PLATFORM_HTONL() macros.

  ++ Bug fixes:
  
  2006-11-30 Christiaan Simons
  * dhcp.c: Fixed false triggers of request_timeout.

  2006-11-28 Christiaan Simons
  * netif.c: In netif_add() fixed missing clear of ip_addr, netmask, gw and flags.

  2006-10-11 Christiaan Simons
  * api_lib.c etharp.c, ip.c, memp.c, stats.c, sys.{c,h} tcp.h:
    Partially accepted patch #5449 for ANSI C compatibility / build fixes.
  * ipv4/lwip/ip.h ipv6/lwip/ip.h: Corrected UDP-Lite protocol
    identifier from 170 to 136 (bug #17574).

  2006-10-10 Christiaan Simons
  * api_msg.c: Fixed Nagle algorithm as reported by Bob Grice.

  2006-08-17 Christiaan Simons
  * udp.c: Fixed bug #17200, added check for broadcast
    destinations for PCBs bound to a unicast address.

  2006-08-07 Christiaan Simons
  * api_msg.c: Flushing TCP output in do_close() (bug #15926).
    
  2006-06-27 Christiaan Simons
  * api_msg.c: Applied patch for cold case (bug #11135).
    In accept_function() ensure newconn->callback is always initialized.

  2006-06-15 Christiaan Simons
  * mem.h: added MEM_SIZE_F alias to fix an ancient cold case (bug #1748),
    facilitate printing of mem_size_t and u16_t statistics.

  2006-06-14 Christiaan Simons
  * api_msg.c: Applied patch #5146 to handle allocation failures
    in accept() by Kevin Lawson.

  2006-05-26 Christiaan Simons
  * api_lib.c: Removed conn->sem creation and destruction 
    from netconn_write() and added sys_sem_new to netconn_new_*.

(STABLE-1_1_1)

  2006-03-03  Christiaan Simons
  * ipv4/ip_frag.c: Added bound-checking assertions on ip_reassbitmap
    access and added pbuf_alloc() return value checks.

  2006-01-01  Leon Woestenberg <leon.woestenberg@gmx.net>
  * tcp_{in,out}.c, tcp_out.c: Removed 'even sndbuf' fix in TCP, which is
    now handled by the checksum routine properly.

  2006-02-27  Leon Woestenberg <leon.woestenberg@gmx.net>
   * pbuf.c: Fix alignment; pbuf_init() would not work unless
     pbuf_pool_memory[] was properly aligned. (Patch by Curt McDowell.)

  2005-12-20  Leon Woestenberg <leon.woestenberg@gmx.net>
  * tcp.c: Remove PCBs which stay in LAST_ACK state too long. Patch
    submitted by Mitrani Hiroshi.
    
  2005-12-15  Christiaan Simons
  * inet.c: Disabled the added summing routine to preserve code space.

  2005-12-14  Leon Woestenberg <leon.woestenberg@gmx.net>
  * tcp_in.c: Duplicate FIN ACK race condition fix by Kelvin Lawson.
    Added Curt McDowell's optimized checksumming routine for future
    inclusion. Need to create test case for unaliged, aligned, odd,
    even length combination of cases on various endianess machines.

  2005-12-09  Christiaan Simons
  * inet.c: Rewrote standard checksum routine in proper portable C.

  2005-11-25  Christiaan Simons
  * udp.c tcp.c: Removed SO_REUSE hack. Should reside in socket code only.
  * *.c: introduced cc.h LWIP_DEBUG formatters matching the u16_t, s16_t,
    u32_t, s32_t typedefs. This solves most debug word-length assumes.  

  2005-07-17 Leon Woestenberg <leon.woestenberg@gmx.net>
  * inet.c: Fixed unaligned 16-bit access in the standard checksum
    routine by Peter Jolasson.
  * slipif.c: Fixed implementation assumption of single-pbuf datagrams.

  2005-02-04 Leon Woestenberg <leon.woestenberg@gmx.net>
  * tcp_out.c: Fixed uninitialized 'queue' referenced in memerr branch.
  * tcp_{out|in}.c: Applied patch fixing unaligned access.

  2005-01-04 Leon Woestenberg <leon.woestenberg@gmx.net>
  * pbuf.c: Fixed missing semicolon after LWIP_DEBUG statement.

  2005-01-03 Leon Woestenberg <leon.woestenberg@gmx.net>
  * udp.c: UDP pcb->recv() was called even when it was NULL.

(STABLE-1_1_0)

  2004-12-28 Leon Woestenberg <leon.woestenberg@gmx.net>
  * etharp.*: Disabled multiple packets on the ARP queue.
    This clashes with TCP queueing.

  2004-11-28 Leon Woestenberg <leon.woestenberg@gmx.net>
  * etharp.*: Fixed race condition from ARP request to ARP timeout.
    Halved the ARP period, doubled the period counts.
    ETHARP_MAX_PENDING now should be at least 2. This prevents
    the counter from reaching 0 right away (which would allow
    too little time for ARP responses to be received).
    
  2004-11-25 Leon Woestenberg <leon.woestenberg@gmx.net>
  * dhcp.c: Decline messages were not multicast but unicast.
  * etharp.c: ETHARP_CREATE is renamed to ETHARP_TRY_HARD.
    Do not try hard to insert arbitrary packet's source address,
    etharp_ip_input() now calls etharp_update() without ETHARP_TRY_HARD. 
    etharp_query() now always DOES call ETHARP_TRY_HARD so that users
    querying an address will see it appear in the cache (DHCP could
    suffer from this when a server invalidly gave an in-use address.)
  * ipv4/ip_addr.h: Renamed ip_addr_maskcmp() to _netcmp() as we are
    comparing network addresses (identifiers), not the network masks
    themselves.
  * ipv4/ip_addr.c: ip_addr_isbroadcast() now checks that the given
    IP address actually belongs to the network of the given interface.

  2004-11-24 Kieran Mansley <kjm25@cam.ac.uk>
  * tcp.c: Increment pcb->snd_buf when ACK is received in SYN_SENT state.

(STABLE-1_1_0-RC1)

  2004-10-16 Kieran Mansley <kjm25@cam.ac.uk>
  * tcp.c: Add code to tcp_recved() to send an ACK (window update) immediately,
	even if one is already pending, if the rcv_wnd is above a threshold
	(currently TCP_WND/2). This avoids waiting for a timer to expire to send a
	delayed ACK in order to open the window if the stack is only receiving data.

  2004-09-12 Kieran Mansley <kjm25@cam.ac.uk>
  * tcp*.*: Retransmit time-out handling improvement by Sam Jansen.

  2004-08-20 Tony Mountifield <tony@softins.co.uk>
  * etharp.c: Make sure the first pbuf queued on an ARP entry
    is properly ref counted.

  2004-07-27 Tony Mountifield <tony@softins.co.uk>
  * debug.h: Added (int) cast in LWIP_DEBUGF() to avoid compiler
    warnings about comparison.
  * pbuf.c: Stopped compiler complaining of empty if statement
    when LWIP_DEBUGF() empty.  Closed an unclosed comment.
  * tcp.c: Stopped compiler complaining of empty if statement
    when LWIP_DEBUGF() empty.
  * ip.h Corrected IPH_TOS() macro: returns a byte, so doesn't need htons().
  * inet.c: Added a couple of casts to quiet the compiler.
    No need to test isascii(c) before isdigit(c) or isxdigit(c).

  2004-07-22 Tony Mountifield <tony@softins.co.uk>
  * inet.c: Made data types consistent in inet_ntoa().
    Added casts for return values of checksum routines, to pacify compiler.
  * ip_frag.c, tcp_out.c, sockets.c, pbuf.c
    Small corrections to some debugging statements, to pacify compiler.

  2004-07-21 Tony Mountifield <tony@softins.co.uk>
  * etharp.c: Removed spurious semicolon and added missing end-of-comment.
  * ethernetif.c Updated low_level_output() to match prototype for
    netif->linkoutput and changed low_level_input() similarly for consistency.
  * api_msg.c: Changed recv_raw() from int to u8_t, to match prototype
    of raw_recv() in raw.h and so avoid compiler error.
  * sockets.c: Added trivial (int) cast to keep compiler happier.
  * ip.c, netif.c Changed debug statements to use the tidier ip4_addrN() macros.
  
(STABLE-1_0_0)

  ++ Changes:

  2004-07-05 Leon Woestenberg <leon.woestenberg@gmx.net>
  * sockets.*: Restructured LWIP_PRIVATE_TIMEVAL. Make sure
    your cc.h file defines this either 1 or 0. If non-defined,
    defaults to 1.
  * .c: Added <string.h> and <errno.h> includes where used.
  * etharp.c: Made some array indices unsigned.

  2004-06-27 Leon Woestenberg <leon.woestenberg@gmx.net>
  * netif.*: Added netif_set_up()/down().
  * dhcp.c: Changes to restart program flow.

  2004-05-07 Leon Woestenberg <leon.woestenberg@gmx.net>
  * etharp.c: In find_entry(), instead of a list traversal per candidate, do a
    single-pass lookup for different candidates. Should exploit locality.

  2004-04-29 Leon Woestenberg <leon.woestenberg@gmx.net>
  * tcp*.c: Cleaned up source comment documentation for Doxygen processing.
  * opt.h: ETHARP_ALWAYS_INSERT option removed to comply with ARP RFC.
  * etharp.c: update_arp_entry() only adds new ARP entries when adviced to by
    the caller. This deprecates the ETHARP_ALWAYS_INSERT overrule option.

  ++ Bug fixes:

  2004-04-27 Leon Woestenberg <leon.woestenberg@gmx.net>
  * etharp.c: Applied patch of bug #8708 by Toni Mountifield with a solution
    suggested by Timmy Brolin. Fix for 32-bit processors that cannot access
    non-aligned 32-bit words, such as soms 32-bit TCP/IP header fields. Fix
    is to prefix the 14-bit Ethernet headers with two padding bytes.

  2004-04-23 Leon Woestenberg <leon.woestenberg@gmx.net>
  * ip_addr.c: Fix in the ip_addr_isbroadcast() check.
  * etharp.c: Fixed the case where the packet that initiates the ARP request
    is not queued, and gets lost. Fixed the case where the packets destination
    address is already known; we now always queue the packet and perform an ARP
    request.
  
(STABLE-0_7_0)

  ++ Bug fixes:

  * Fixed TCP bug for SYN_SENT to ESTABLISHED state transition.
  * Fixed TCP bug in dequeueing of FIN from out of order segment queue.
  * Fixed two possible NULL references in rare cases.

(STABLE-0_6_6)

  ++ Bug fixes:

  * Fixed DHCP which did not include the IP address in DECLINE messages.

  ++ Changes:

  * etharp.c has been hauled over a bit.

(STABLE-0_6_5)

  ++ Bug fixes:

  * Fixed TCP bug induced by bad window resizing with unidirectional TCP traffic.
  * Packets sent from ARP queue had invalid source hardware address.

  ++ Changes:

  * Pass-by ARP requests do now update the cache.

  ++ New features:

  * No longer dependent on ctype.h.
  * New socket options.
  * Raw IP pcb support.

(STABLE-0_6_4)

  ++ Bug fixes:

  * Some debug formatters and casts fixed.
  * Numereous fixes in PPP.

  ++ Changes:

  * DEBUGF now is LWIP_DEBUGF
  * pbuf_dechain() has been re-enabled.
  * Mentioned the changed use of CVS branches in README.

(STABLE-0_6_3)

  ++ Bug fixes:

  * Fixed pool pbuf memory leak in pbuf_alloc().
    Occured if not enough PBUF_POOL pbufs for a packet pbuf chain.
    Reported by Savin Zlobec.

  * PBUF_POOL chains had their tot_len field not set for non-first
    pbufs. Fixed in pbuf_alloc().

  ++ New features:

  * Added PPP stack contributed by Marc Boucher

  ++ Changes:

  * Now drops short packets for ICMP/UDP/TCP protocols. More robust.

  * ARP queueuing now queues the latest packet instead of the first.
    This is the RFC recommended behaviour, but can be overridden in
    lwipopts.h.

(0.6.2)

  ++ Bugfixes:

  * TCP has been fixed to deal with the new use of the pbuf->ref
    counter.

  * DHCP dhcp_inform() crash bug fixed.

  ++ Changes:

  * Removed pbuf_pool_free_cache and pbuf_pool_alloc_cache. Also removed
    pbuf_refresh(). This has sped up pbuf pool operations considerably.
    Implemented by David Haas.

(0.6.1)

  ++ New features:

  * The packet buffer implementation has been enhanced to support
    zero-copy and copy-on-demand for packet buffers which have their
    payloads in application-managed memory.
    Implemented by David Haas.

    Use PBUF_REF to make a pbuf refer to RAM. lwIP will use zero-copy
    if an outgoing packet can be directly sent on the link, or perform
    a copy-on-demand when necessary.

    The application can safely assume the packet is sent, and the RAM
    is available to the application directly after calling udp_send()
    or similar function.

  ++ Bugfixes:

  * ARP_QUEUEING should now correctly work for all cases, including
    PBUF_REF.
    Implemented by Leon Woestenberg.

  ++ Changes:

  * IP_ADDR_ANY is no longer a NULL pointer. Instead, it is a pointer
    to a '0.0.0.0' IP address.

  * The packet buffer implementation is changed. The pbuf->ref counter
    meaning has changed, and several pbuf functions have been
    adapted accordingly.

  * netif drivers have to be changed to set the hardware address length field
    that must be initialized correctly by the driver (hint: 6 for Ethernet MAC).
    See the contrib/ports/c16x cs8900 driver as a driver example.

  * netif's have a dhcp field that must be initialized to NULL by the driver.
    See the contrib/ports/c16x cs8900 driver as a driver example.

(0.5.x) This file has been unmaintained up to 0.6.1. All changes are
  logged in CVS but have not been explained here.

(0.5.3) Changes since version 0.5.2

  ++ Bugfixes:

  * memp_malloc(MEMP_API_MSG) could fail with multiple application
    threads because it wasn't protected by semaphores.

  ++ Other changes:

  * struct ip_addr now packed.

  * The name of the time variable in arp.c has been changed to ctime
    to avoid conflicts with the time() function.

(0.5.2) Changes since version 0.5.1

  ++ New features:

  * A new TCP function, tcp_tmr(), now handles both TCP timers.

  ++ Bugfixes:

  * A bug in tcp_parseopt() could cause the stack to hang because of a
    malformed TCP option.

  * The address of new connections in the accept() function in the BSD
    socket library was not handled correctly.

  * pbuf_dechain() did not update the ->tot_len field of the tail.

  * Aborted TCP connections were not handled correctly in all
    situations.

  ++ Other changes:

  * All protocol header structs are now packed.

  * The ->len field in the tcp_seg structure now counts the actual
    amount of data, and does not add one for SYN and FIN segments.

(0.5.1) Changes since version 0.5.0

  ++ New features:

  * Possible to run as a user process under Linux.

  * Preliminary support for cross platform packed structs.

  * ARP timer now implemented.

  ++ Bugfixes:

  * TCP output queue length was badly initialized when opening
    connections.

  * TCP delayed ACKs were not sent correctly.

  * Explicit initialization of BSS segment variables.

  * read() in BSD socket library could drop data.

  * Problems with memory alignment.

  * Situations when all TCP buffers were used could lead to
    starvation.

  * TCP MSS option wasn't parsed correctly.

  * Problems with UDP checksum calculation.

  * IP multicast address tests had endianess problems.

  * ARP requests had wrong destination hardware address.

  ++ Other changes:

  * struct eth_addr changed from u16_t[3] array to u8_t[6].

  * A ->linkoutput() member was added to struct netif.

  * TCP and UDP ->dest_* struct members where changed to ->remote_*.

  * ntoh* macros are now null definitions for big endian CPUs.

(0.5.0) Changes since version 0.4.2

  ++ New features:

  * Redesigned operating system emulation layer to make porting easier.

  * Better control over TCP output buffers.

  * Documenation added.

  ++ Bugfixes:

  * Locking issues in buffer management.

  * Bugfixes in the sequential API.

  * IP forwarding could cause memory leakage. This has been fixed.

  ++ Other changes:

  * Directory structure somewhat changed; the core/ tree has been
    collapsed.

(0.4.2) Changes since version 0.4.1

  ++ New features:

  * Experimental ARP implementation added.

  * Skeleton Ethernet driver added.

  * Experimental BSD socket API library added.

  ++ Bugfixes:

  * In very intense situations, memory leakage could occur. This has
    been fixed.

  ++ Other changes:

  * Variables named "data" and "code" have been renamed in order to
    avoid name conflicts in certain compilers.

  * Variable++ have in appliciable cases been translated to ++variable
    since some compilers generate better code in the latter case.

(0.4.1) Changes since version 0.4

  ++ New features:

  * TCP: Connection attempts time out earlier than data
    transmissions. Nagle algorithm implemented. Push flag set on the
    last segment in a burst.

  * UDP: experimental support for UDP-Lite extensions.

  ++ Bugfixes:

  * TCP: out of order segments were in some cases handled incorrectly,
    and this has now been fixed. Delayed acknowledgements was broken
    in 0.4, has now been fixed. Binding to an address that is in use
    now results in an error. Reset connections sometimes hung an
    application; this has been fixed.

  * Checksum calculation sometimes failed for chained pbufs with odd
    lengths. This has been fixed.

  * API: a lot of bug fixes in the API. The UDP API has been improved
    and tested. Error reporting and handling has been
    improved. Logical flaws and race conditions for incoming TCP
    connections has been found and removed.

  * Memory manager: alignment issues. Reallocating memory sometimes
    failed, this has been fixed.

  * Generic library: bcopy was flawed and has been fixed.

  ++ Other changes:

  * API: all datatypes has been changed from generic ones such as
    ints, to specified ones such as u16_t. Functions that return
    errors now have the correct type (err_t).

  * General: A lot of code cleaned up and debugging code removed. Many
    portability issues have been fixed.

  * The license was changed; the advertising clause was removed.

  * C64 port added.

  * Thanks: Huge thanks go to Dagan Galarneau, Horst Garnetzke, Petri
    Kosunen, Mikael Caleres, and Frits Wilmink for reporting and
    fixing bugs!

(0.4) Changes since version 0.3.1

  * Memory management has been radically changed; instead of
    allocating memory from a shared heap, memory for objects that are
    rapidly allocated and deallocated is now kept in pools. Allocation
    and deallocation from those memory pools is very fast. The shared
    heap is still present but is used less frequently.

  * The memory, memory pool, and packet buffer subsystems now support
    4-, 2-, or 1-byte alignment.

  * "Out of memory" situations are handled in a more robust way.

  * Stack usage has been reduced.

  * Easier configuration of lwIP parameters such as memory usage,
    TTLs, statistics gathering, etc. All configuration parameters are
    now kept in a single header file "lwipopts.h".

  * The directory structure has been changed slightly so that all
    architecture specific files are kept under the src/arch
    hierarchy.

  * Error propagation has been improved, both in the protocol modules
    and in the API.

  * The code for the RTXC architecture has been implemented, tested
    and put to use.

  * Bugs have been found and corrected in the TCP, UDP, IP, API, and
    the Internet checksum modules.

  * Bugs related to porting between a 32-bit and a 16-bit architecture
    have been found and corrected.

  * The license has been changed slightly to conform more with the
    original BSD license, including the advertisement clause.

(0.3.1) Changes since version 0.3

  * Fix of a fatal bug in the buffer management. Pbufs with allocated
    RAM never returned the RAM when the pbuf was deallocated.

  * TCP congestion control, window updates and retransmissions did not
    work correctly. This has now been fixed.

  * Bugfixes in the API.

(0.3) Changes since version 0.2

  * New and improved directory structure. All include files are now
    kept in a dedicated include/ directory.

  * The API now has proper error handling. A new function,
    netconn_err(), now returns an error code for the connection in
    case of errors.

  * Improvements in the memory management subsystem. The system now
    keeps a pointer to the lowest free memory block. A new function,
    mem_malloc2() tries to allocate memory once, and if it fails tries
    to free some memory and retry the allocation.

  * Much testing has been done with limited memory
    configurations. lwIP now does a better job when overloaded.

  * Some bugfixes and improvements to the buffer (pbuf) subsystem.

  * Many bugfixes in the TCP code:

    - Fixed a bug in tcp_close().

    - The TCP receive window was incorrectly closed when out of
      sequence segments was received. This has been fixed.

    - Connections are now timed-out of the FIN-WAIT-2 state.

    - The initial congestion window could in some cases be too
      large. This has been fixed.

    - The retransmission queue could in some cases be screwed up. This
      has been fixed.

    - TCP RST flag now handled correctly.

    - Out of sequence data was in some cases never delivered to the
      application. This has been fixed.

    - Retransmitted segments now contain the correct acknowledgment
      number and advertised window.

    - TCP retransmission timeout backoffs are not correctly computed
      (ala BSD). After a number of retransmissions, TCP now gives up
      the connection.

  * TCP connections now are kept on three lists, one for active
    connections, one for listening connections, and one for
    connections that are in TIME-WAIT. This greatly speeds up the fast
    timeout processing for sending delayed ACKs.

  * TCP now provides proper feedback to the application when a
    connection has been successfully set up.

  * More comments have been added to the code. The code has also been
    somewhat cleaned up.

(0.2) Initial public release.
