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TM4C129 系列网卡硬件有校验和吗?请教各位了



我发送udp包时,软件没有加校验和,但是截包工具抓到有checksum值。

  • tm4c1294本身可以计算icmp数据包的校验和,在enet_uip示例中,uip.c

    #if UIP_OFFLOAD_ICMP_CHKSUM
      /* If the hardware is inserting ICMP checksums for us, clear the field to
         ensure that the correct checksum is calculated. */
      ICMPBUF->icmpchksum = 0;

    若在preprocessor 有添加 UIP_OFFLOAD_ICMP_CHKSUM 则硬件上就会处理checksum

  • lwip有相关配置说明吗?我用的是lwip
  • 您可以尝试在工程内搜索关键字 checksum

    在lwiplib.c内

    //*****************************************************************************
    //
    // Ensure that ICMP checksum offloading is enabled; otherwise the TM4C129
    // driver will not operate correctly.
    //
    //*****************************************************************************
    #ifndef LWIP_OFFLOAD_ICMP_CHKSUM
    #define LWIP_OFFLOAD_ICMP_CHKSUM 1
    #endif