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.)HISTORY(HEAD)  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: