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lwIP mirror from http://git.savannah.gnu.org/cgit/lwip.git
d518f5f307
Don't process input data if PPPoS is closed, it helps using pppos_input() from a different context to prevent pppos_input() to modify PPPoS RX machine state on a closed PPPoS session. It also prevents allocating pbuf (which are going to be tossed out by PPP core) and parsing serial input on a closed session. It only mitigates the fact that this function is actually NOT thread safe in absolutely all cases, it does not fix it but it helps for a low cost. For example user application should never call pppos_input() while pppos_connect() or pppos_listen() is currently running because both of them are freeing any input pbuf left over from the last session before resetting the PPPoS state, they really have to to prevent pbuf leaks. We cannot fix that easily because we don't have spinlock with an irqsave/irqrestore helper for IRQ contexts. Mutex cannot be used in interrupt contexts (or again, with an IRQ mutex helper). We are going to improve the documentation on this point. |
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INTRODUCTION lwIP is a small independent implementation of the TCP/IP protocol suite that has been developed by Adam Dunkels at the Computer and Networks Architectures (CNA) lab at the Swedish Institute of Computer Science (SICS). The focus of the lwIP TCP/IP implementation is to reduce the RAM usage while still having a full scale TCP. This making lwIP suitable for use in embedded systems with tens of kilobytes of free RAM and room for around 40 kilobytes of code ROM. FEATURES * IP (Internet Protocol) including packet forwarding over multiple network interfaces * ICMP (Internet Control Message Protocol) for network maintenance and debugging * IGMP (Internet Group Management Protocol) for multicast traffic management * UDP (User Datagram Protocol) including experimental UDP-lite extensions * TCP (Transmission Control Protocol) with congestion control, RTT estimation and fast recovery/fast retransmit * Specialized raw/native API for enhanced performance * Optional Berkeley-like socket API * DNS (Domain names resolver) * SNMP (Simple Network Management Protocol) * DHCP (Dynamic Host Configuration Protocol) * AUTOIP (for IPv4, conform with RFC 3927) * PPP (Point-to-Point Protocol) * ARP (Address Resolution Protocol) for Ethernet LICENSE lwIP is freely available under a BSD license. DEVELOPMENT lwIP has grown into an excellent TCP/IP stack for embedded devices, and developers using the stack often submit bug fixes, improvements, and additions to the stack to further increase its usefulness. Development of lwIP is hosted on Savannah, a central point for software development, maintenance and distribution. Everyone can help improve lwIP by use of Savannah's interface, CVS and the mailing list. A core team of developers will commit changes to the CVS source tree. The lwIP TCP/IP stack is maintained in the 'lwip' CVS module and contributions (such as platform ports) are in the 'contrib' module. See doc/savannah.txt for details on CVS server access for users and developers. Last night's CVS tar ball can be downloaded from: http://savannah.gnu.org/cvs.backups/lwip.tar.gz [CHANGED - NEEDS FIXING] The current CVS trees are web-browsable: http://savannah.nongnu.org/cgi-bin/viewcvs/lwip/lwip/ http://savannah.nongnu.org/cgi-bin/viewcvs/lwip/contrib/ Submit patches and bugs via the lwIP project page: http://savannah.nongnu.org/projects/lwip/ DOCUMENTATION The original out-dated homepage of lwIP and Adam Dunkels' papers on lwIP are at the official lwIP home page: http://www.sics.se/~adam/lwip/ Self documentation of the source code is regularly extracted from the current CVS sources and is available from this web page: http://www.nongnu.org/lwip/ There is now a constantly growin wiki about lwIP at http://lwip.wikia.com/wiki/LwIP_Wiki Also, there are mailing lists you can subscribe at http://savannah.nongnu.org/mail/?group=lwip plus searchable archives: http://lists.nongnu.org/archive/html/lwip-users/ http://lists.nongnu.org/archive/html/lwip-devel/ Reading Adam's papers, the files in docs/, browsing the source code documentation and browsing the mailing list archives is a good way to become familiar with the design of lwIP. Adam Dunkels <adam@sics.se> Leon Woestenberg <leon.woestenberg@gmx.net>