ip.lst

来自「单片机控制RTL8019AS的程序,C语言编写,仿真通过.」· LST 代码 · 共 172 行

C51 COMPILER V7.06   IP                                                                    10/09/2006 21:51:55 PAGE 1   


C51 COMPILER V7.06, COMPILATION OF MODULE IP
OBJECT MODULE PLACED IN ip.OBJ
COMPILER INVOKED BY: D:\Program Files\Keil\C51\BIN\C51.EXE ip.c BROWSE DEBUG OBJECTEXTEND

stmt level    source

   1          //-----------------------------------------------------------------------------
   2          // Net IP.C
   3          // This module is the IP layer
   4          // Refer to RFC 791, 1122, and RFC 815 (fragmentation)
   5          //-----------------------------------------------------------------------------
   6          #include <string.h>
   7          #include <general.h>
   8          
   9          
  10          extern ULONG code my_ipaddr;
  11          WAIT xdata wait;
  12          
  13          
  14          //------------------------------------------------------------------------
  15          // This handles outgoing IP datagrams.  It adds the 20 byte IP header
  16          // and checksum then forwards the IP datagram to the Ethernet layer
  17          // for sending. See "TCP/IP Illustrated, Volume 1" Sect 3.2
  18          //------------------------------------------------------------------------
  19          void ip_send(UCHAR xdata * outbuf, ULONG ipaddr, UCHAR proto_id, UINT len)
  20          {
  21   1         IP_HEADER xdata * ip;
  22   1         UCHAR xdata * hwaddr;
  23   1         static UINT ip_ident = 0;
  24   1         
  25   1         ip = (IP_HEADER xdata *)(outbuf + 14);
  26   1         ip->ver_len = 0x45;          // IPv4 with 20 byte header
  27   1         ip->type_of_service = 0;
  28   1         ip->total_length = 20 + len;
  29   1         ip->identifier = ip_ident++;     // sequential identifier
  30   1         ip->fragment_info = 0;           // not fragmented
  31   1         ip->time_to_live = 32;           // max hops
  32   1         ip->protocol_id = proto_id;      // type of payload
  33   1         ip->header_cksum = 0;
  34   1         ip->source_ipaddr = my_ipaddr;
  35   1         
  36   1         // Outgoing IP address
  37   1         ip->dest_ipaddr = ipaddr;
  38   1      
  39   1         // Compute and insert complement of checksum of ip header
  40   1         // Outgoing ip header length is always 20 bytes
  41   1         ip->header_cksum = ~cksum(outbuf + 14, 20);
  42   1         
  43   1         // Use ARP to get hardware address to send this to
  44   1         hwaddr = arp_resolve(ip->dest_ipaddr);
  45   1              
  46   1              // Null means that the ARP resolver did not find the IP address
  47   1              // in its cache so had to send an ARP request
  48   1              if (hwaddr == NULL)
  49   1              {
  50   2                      // Fill in the destination information so ehrn the ARP response
  51   2                      // arrives we can identify it and know what to do when we get it
  52   2            wait.buf = outbuf;
  53   2                      wait.ipaddr = ip->dest_ipaddr;
  54   2                      wait.proto_id = proto_id;
  55   2                      wait.len = len;
C51 COMPILER V7.06   IP                                                                    10/09/2006 21:51:55 PAGE 2   

  56   2                      wait.timer = ARP_TIMEOUT; 
  57   2            return;
  58   2              }       
  59   1              
  60   1              eth_send(outbuf, hwaddr, IP_PACKET, 20 + len);
  61   1      }
  62          
  63          
  64          
  65          //------------------------------------------------------------------------
  66          // This handles incoming IP datagrams from the Ethernet layer
  67          // See "TCP/IP Illustrated, Volume 1" Sect 3.2
  68          //------------------------------------------------------------------------
  69          void ip_rcve(UCHAR xdata * inbuf)
  70          {
  71   1              IP_HEADER xdata * ip;
  72   1              UINT idata header_len, payload_len;
  73   1                      
  74   1         ip = (IP_HEADER xdata *)(inbuf + 14);
  75   1                  
  76   1         // Make sure it is addressed to my IP address
  77   1         if (ip->dest_ipaddr != my_ipaddr) return;
  78   1      
  79   1         // Validate checksum of ip header
  80   1              header_len = 4 * (0x0F & ip->ver_len);
  81   1              payload_len = ip->total_length - header_len;
  82   1         if (cksum(inbuf + 14, header_len) != 0xFFFF)
  83   1              {
  84   2                 return; 
  85   2         }
  86   1              
  87   1              // Make sure incoming message is IP version 4
  88   1              if ((ip->ver_len >> 4) != 0x04)
  89   1              {
  90   2              return;
  91   2              }
  92   1      
  93   1              // Make sure incoming message is not fragmented because
  94   1         // we cannot handle fragmented messages
  95   1         if ((ip->fragment_info & 0x3FFF) != 0)
  96   1         {
  97   2                 return; 
  98   2         }
  99   1      
 100   1         // At this point we have received a valid IP datagram addressed
 101   1         // to me.  We do not use header options, and do not forward
 102   1         // messages, so in the unlikely event there are header options,
 103   1         // delete them and shift the data down. The advantage is that
 104   1         // layers such as UDP and TCP know where their data starts
 105   1              if (header_len > 20)
 106   1              {
 107   2                              
 108   2            // Use memmove because of overlap
 109   2            memmove(inbuf + 34, inbuf + 14 + header_len, payload_len);
 110   2      
 111   2                      // Adjust info to reflect the move
 112   2                      header_len = 20;
 113   2                      ip->ver_len = 0x45;
 114   2                      ip->total_length = 20 + payload_len;
 115   2              }
 116   1              
 117   1              
C51 COMPILER V7.06   IP                                                                    10/09/2006 21:51:55 PAGE 3   

 118   1              // Look at protocol ID byte and call the appropriate
 119   1         // function to handle the received message.  See 
 120   1         // "TCP/IP Illustrated, Volume 1" Sect 1.7 and RFC 791
 121   1         // for values for various protocols
 122   1         switch (ip->protocol_id)
 123   1              {
 124   2                 case ICMP_TYPE:
 125   2            icmp_rcve(inbuf, payload_len);
 126   2                      break;
 127   2      
 128   2            case IGMP_TYPE:
 129   2                      // We cannot handle IGMP messages
 130   2                      break;
 131   2                        
 132   2                      case UDP_TYPE:
 133   2                      break;
 134   2      
 135   2                      case TCP_TYPE:   
 136   2            tcp_rcve(inbuf, payload_len);
 137   2                      break;
 138   2      
 139   2            default:
 140   2            break;
 141   2         }
 142   1      }
 143          
 144          


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =    631    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =     10    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =      2      15
   IDATA SIZE       =   ----       4
   BIT SIZE         =   ----    ----
END OF MODULE INFORMATION.


C51 COMPILATION COMPLETE.  0 WARNING(S),  0 ERROR(S)