C51 COMPILER V7.09   ICMP                                                                  07/07/2004 14:57:20 PAGE 1   


C51 COMPILER V7.09, COMPILATION OF MODULE ICMP
OBJECT MODULE PLACED IN ICMP.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE ICMP.C OPTIMIZE(9,SPEED) BROWSE DEBUG OBJECTEXTEND

line level    source

   1          //-----------------------------------------------------------------------------
   2          // Net ICMP.C
   3          //
   4          // This module handles ICMP messages
   5          // Refer to RFC 792, 896, 950, 1122, and 1191
   6          //-----------------------------------------------------------------------------
   7          #include <string.h>
   8          #include <stdlib.h>
   9          #include "C8051f.h"
  10          #include "net.h"
  11          #include "cksum.h"
  12          #include "ip.h"
  13          #include "serial.h"
  14          #include "icmp.h"
  15          
  16          extern UCHAR idata debug;
  17          
  18          
  19          //------------------------------------------------------------------------
  20          // This builds a ping response message.  It allocates memory for the
  21          // entire outgoing message, including Eth and IP headers.  See "TCP/IP
  22          // Illustrated, Volume 1" Sect 7.2 for info on Ping messages
  23          //------------------------------------------------------------------------
  24          void ping_send(UCHAR xdata * inbuf, ULONG ipaddr, UINT len)
  25          {
  26   1         PING_HEADER xdata * ping_in;
  27   1         PING_HEADER xdata * ping_out;
  28   1         UCHAR xdata * outbuf;
  29   1                  
  30   1         ping_in = (PING_HEADER xdata *)(inbuf + 34);
  31   1            
  32   1         // Allocate memory for entire outgoing message
  33   1         outbuf = (UCHAR xdata *)malloc(len + 34);
  34   1         if (outbuf == NULL)
  35   1         {
  36   2            if (debug) serial_send("PING: Oops, out of memory\r");
  37   2            return;
  38   2         }      
  39   1            
  40   1         // Ping response message payload starts at offset 34
  41   1         ping_out = (PING_HEADER xdata *)(outbuf + 34);
  42   1      
  43   1         ping_out->msg_type = 0;
  44   1         ping_out->msg_code = 0;
  45   1         ping_out->checksum = 0;
  46   1         ping_out->identifier = ping_in->identifier;
  47   1         ping_out->sequence = ping_in->sequence;
  48   1         
  49   1         memcpy(&ping_out->echo_data, &ping_in->echo_data, len - 8);
  50   1                  
  51   1         // Compute checksum over the ICMP header plus
  52   1              // optional data and insert complement
  53   1         ping_out->checksum = ~cksum(outbuf + 34, len);
  54   1                              
  55   1         if (debug) serial_send("ICMP: Sending response to IP layer\r");
C51 COMPILER V7.09   ICMP                                                                  07/07/2004 14:57:20 PAGE 2   

  56   1      
  57   1         ip_send(outbuf, ipaddr, ICMP_TYPE, len);
  58   1      }
  59          
  60          
  61          
  62          //------------------------------------------------------------------------
  63          // This builds an outgoing ICMP destination port unreachable response
  64          // message.  See See "TCP/IP Illustrated, Volume 1" Sect 6.5.  This
  65          // message is typically sent in response to a UDP message directed
  66          // to a port that has no corresponding application running. 
  67          // Todo: The spec says we should return all options that were in
  68          // the original incoming IP header.  Right now we cut off everything
  69          // after the first 20 bytes. 
  70          //------------------------------------------------------------------------
  71          void dest_unreach_send(UCHAR xdata * inbuf, ULONG ipaddr)
  72          {
  73   1         UCHAR xdata * outbuf;
  74   1         ICMP_ERR_HEADER xdata * icmp;
  75   1                  
  76   1         // Allocate memory for entire outgoing message
  77   1         // including eth and IP haders.  Always 70 bytes
  78   1         outbuf = (UCHAR xdata *)malloc(70);
  79   1         if (outbuf == NULL)
  80   1         {
  81   2            if (debug) serial_send("ICMP: Oops, out of memory\r");
  82   2            return;
  83   2         }      
  84   1            
  85   1         icmp = (ICMP_ERR_HEADER xdata *)(outbuf + 34);
  86   1         
  87   1         // Fill in ICMP error message header
  88   1         icmp->msg_type = 3;   // destination unreachable
  89   1         icmp->msg_code = 3;   // port unreachable
  90   1         icmp->checksum = 0;
  91   1            
  92   1         // Fill in ICMP error message data
  93   1         icmp->msg_data = 0;
  94   1                 
  95   1         // Copy in 20 byte original incoming IP header
  96   1         // plus 8 bytes of data
  97   1         memcpy(&icmp->echo_data, inbuf + 14, 28);
  98   1                                     
  99   1         // Compute checksum over the 36 byte long ICMP
 100   1         // header plus data and insert complement
 101   1         icmp->checksum = ~cksum(outbuf + 34, 36);
 102   1            
 103   1         // Forward message to the IP layer
 104   1         if (debug) serial_send("ICMP: Sending dest unreach to IP layer\r");
 105   1         ip_send(outbuf, ipaddr, ICMP_TYPE, 36);
 106   1      }
 107          
 108          
 109          
 110          
 111          //------------------------------------------------------------------------
 112          // This handles incoming ICMP messages.  See "TCP/IP Illustrated,
 113          // Volume 1" Sect 6.2 for discussion of the various ICMP messages
 114          //------------------------------------------------------------------------
 115          void icmp_rcve(UCHAR xdata * inbuf, UINT len)
 116          {
 117   1         IP_HEADER * ip;
C51 COMPILER V7.09   ICMP                                                                  07/07/2004 14:57:20 PAGE 3   

 118   1         UCHAR idata msg_type;
 119   1         UINT idata temp;
 120   1         
 121   1         // Allow for 14 bytes eth header
 122   1         ip = (IP_HEADER *)(inbuf + 14);
 123   1              
 124   1         // IP header has been adjusted if necessary to always be 
 125   1              // 20 bytes so message starts at an offset of 34
 126   1         // Validate checksum of entire ICMP message incl data 
 127   1              temp = cksum(inbuf + 34, len);
 128   1              
 129   1              if (temp != 0xFFFF)
 130   1              {
 131   2                      if (debug) serial_send("ICMP: Error, cksum bad\r");
 132   2            return; 
 133   2         }
 134   1            
 135   1         // Switch on the message type
 136   1         msg_type = *(inbuf + 34);
 137   1         switch(msg_type)
 138   1         {
 139   2            case 3:
 140   2            if (debug) serial_send("ICMP: Dest unreachable rcvd\r");
 141   2            break;
 142   2      
 143   2                 case 8:
 144   2            if (debug) serial_send("ICMP: Ping rcvd\r");
 145   2            ping_send(inbuf, ip->source_ipaddr, len); 
 146   2            break;
 147   2      
 148   2            default:
 149   2            if (debug) serial_send("ICMP: Error, unknown msg rcvd\r");
 150   2            break;
 151   2         }
 152   1      }
 153          
 154          


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =    600    ----
   CONSTANT SIZE    =    231    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----      31
   IDATA SIZE       =   ----       3
   BIT SIZE         =   ----    ----
END OF MODULE INFORMATION.


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