LwIP，全称为"Lightweight IP"，是一款开源、轻量级的TCP/IP协议栈，主要用于嵌入式系统。LwIP V2.1.2是该项目的最新版本，相较于早期版本，它包含了更多的优化和功能改进，使得在资源有限的硬件平台上实现网络通信变得更加高效和可靠。 LwIP的核心设计目标是在最小化内存占用和处理器资源需求的同时，提供与标准TCP/IP协议栈相当的功能。其设计理念使得它成为物联网设备、嵌入式系统、以及各种微控制器平台的理想选择。LwIP V2.1.2主要包含以下几个关键组件： 1. **TCP（传输控制协议）**：LwIP实现了完整的TCP协议，支持连接管理、流量控制、拥塞控制等功能。它采用滑动窗口机制来确保数据的可靠传输，并通过重传机制处理丢失的数据包。 2. **UDP（用户数据报协议）**：LwIP提供了UDP协议的支持，适合于实时性要求高的应用，如DNS查询、VoIP等。UDP不提供连接状态和错误检测，因此速度较快但可靠性较低。 3. **IP（互联网协议）**：LwIP实现了IPv4和IPv6，处理网络层的路由和寻址问题，允许不同网络之间的通信。 4. **ICMP（Internet控制消息协议）**：用于网络诊断，例如回显请求（ping）和错误报告。 5. **DHCP（动态主机配置协议）**：允许设备动态获取IP地址、子网掩码、默认网关等网络配置信息。 6. **ARP（地址解析协议）**：负责将IP地址转换为物理MAC地址，实现局域网内的通信。 7. **PBUF（协议缓冲区）**：LwIP使用PBUF结构来管理数据包，它能够适应不同层次的数据结构，方便数据在协议栈各层之间的传递。 8. **API（应用程序接口）**：LwIP提供了一套丰富的API供上层应用调用，包括套接字接口，让开发者可以像使用标准socket API一样使用LwIP。 9. **多线程支持**：LwIP允许在多线程环境中使用，这在某些系统中是必要的，以确保网络操作与应用逻辑的并发执行。 10. **内存管理**：LwIP具有自己的内存管理系统，可以灵活地配置内存池，以适应不同场景下的内存需求。 LwIP STABLE-2_1_2_RELEASE这个压缩包包含了LwIP V2.1.2的所有源代码文件，开发者可以通过编译这些源码将其移植到目标平台。移植过程可能涉及到调整内存池大小、中断处理、网络接口驱动等环节，以确保LwIP能正确地在特定硬件上运行。 在实际开发中，LwIP的用户可以根据项目需求，裁剪或扩展协议栈功能，比如添加SSL/TLS支持，或者集成特定的网络服务。同时，LwIP的模块化设计使得调试和优化变得更为方便，开发者可以通过日志输出、性能分析等手段对协议栈进行深度定制。 LwIP V2.1.2是一个强大而灵活的TCP/IP协议栈解决方案，它在保持低资源占用的同时，提供了丰富的网络功能，是嵌入式系统开发者的有力工具。

本源码主要是LWIP源码及移植说明。实例有测试过。

LWIP官方源码.需要可以下载！

INTRODUCTION lwIP is a small independent implementation of the TCP/IP protocol suite. 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. lwIP was originally developed by Adam Dunkels at the Computer and Networks Architectures (CNA) lab at the Swedish Institute of Computer Science (SICS) and is now developed and maintained by a worldwide network of developers. FEATURES * IP (Internet Protocol, IPv4 and IPv6) 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 * MLD (Multicast listener discovery for IPv6). Aims to be compliant with RFC 2710. No support for MLDv2 * ND (Neighbor discovery and stateless address autoconfiguration for IPv6). Aims to be compliant with RFC 4861 (Neighbor discovery) and RFC 4862 (Address autoconfiguration) * DHCP, AutoIP/APIPA (Zeroconf), ACD (Address Conflict Detection) and (stateless) DHCPv6 * UDP (User Datagram Protocol) including experimental UDP-lite extensions * TCP (Transmission Control Protocol) with congestion control, RTT estimation fast recovery/fast retransmit and sending SACKs * raw/native API for enhanced performance * Optional Berkeley-like socket API * TLS: optional layered TCP ("altcp") for nearly transparent TLS for any TCP-based protocol (ported to mbedTLS) (see changelog for more info) * PPPoS and PPPoE (Point-to-point protocol over Serial/Ethernet) * DNS (Domain name resolver incl. mDNS) * 6LoWPAN (via IEEE 802.15.4, BLE or ZEP) APPLICATIONS * HTTP server with SSI and CGI (HTTPS via altcp) * SNMPv2c agent with MIB compiler (Simple Network Management Protocol), v3 via altcp * SNTP (Simple network time protocol) * NetBIOS name service responder * MDNS (Multicast DNS) responder * iPerf server implementation * MQTT client (TLS support via altcp) 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, Git and the mailing list. A core team of developers will commit changes to the Git source tree. The lwIP TCP/IP stack is maintained in the 'lwip' Git module and contributions (such as platform ports) are in the 'contrib' Git module. See doc/savannah.txt for details on Git server access for users and developers. The current Git trees are web-browsable: http://git.savannah.gnu.org/cgit/lwip.git http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git Submit patches and bugs via the lwIP project page: http://savannah.nongnu.org/projects/lwip/ Continuous integration builds (GCC, clang): https://travis-ci.org/lwip-tcpip/lwip DOCUMENTATION Self documentation of the source code is regularly extracted from the current Git sources and is available from this web page: http://www.nongnu.org/lwip/ 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/ There is a wiki about lwIP at http://lwip.wikia.com/wiki/LwIP_Wiki You might get questions answered there, but unfortunately, it is not as well maintained as it should be. lwIP was originally written by Adam Dunkels: http://dunkels.com/adam/ 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 Leon Woestenberg

包括5篇lwip的中文资料和1.3.2、1.4.0的源码 lwip源码详解_狗拿耗子 lwip协议源码详解 lwIP协议栈分析 lwip协议栈设计与实现-中文 焦海波翻译 等