📄 icmp.lst
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C51 COMPILER V7.06 ICMP 06/26/2004 13:41:25 PAGE 1
C51 COMPILER V7.06, COMPILATION OF MODULE ICMP
OBJECT MODULE PLACED IN ICMP.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE ICMP.C LARGE BROWSE DEBUG OBJECTEXTEND
stmt 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 <stdio.h>
10 #include <reg89C58.h>
11 #include "net.h"
12 #include "cksum.h"
13 #include "ip.h"
14 //#include "serial.h"
15 #include "icmp.h"
16
17 extern UCHAR idata debug;
18
19
20 //------------------------------------------------------------------------
21 // This builds a ping response message. It allocates memory for the
22 // entire outgoing message, including Eth and IP headers. See "TCP/IP
23 // Illustrated, Volume 1" Sect 7.2 for info on Ping messages
24 //------------------------------------------------------------------------
25 void ping_send(UCHAR xdata * inbuf, ULONG ipaddr, UINT len)
26 {
27 1 PING_HEADER xdata * ping_in;
28 1 PING_HEADER xdata * ping_out;
29 1 UCHAR xdata * outbuf;
30 1
31 1 ping_in = (PING_HEADER xdata *)(inbuf + 34);
32 1
33 1 // Allocate memory for entire outgoing message
34 1 outbuf = (UCHAR xdata *)malloc(len + 34);
35 1 if (outbuf == NULL)
36 1 {
37 2 // if (debug) printf("PING: Oops, out of memory\n");
38 2 return;
39 2 }
40 1
41 1 // Ping response message payload starts at offset 34
42 1 ping_out = (PING_HEADER xdata *)(outbuf + 34);
43 1
44 1 ping_out->msg_type = 0;
45 1 ping_out->msg_code = 0;
46 1 ping_out->checksum = 0;
47 1 ping_out->identifier = ping_in->identifier;
48 1 ping_out->sequence = ping_in->sequence;
49 1
50 1 memcpy(&ping_out->echo_data, &ping_in->echo_data, len - 8);
51 1
52 1 // Compute checksum over the ICMP header plus
53 1 // optional data and insert complement
54 1 ping_out->checksum = ~cksum(outbuf + 34, len);
55 1
C51 COMPILER V7.06 ICMP 06/26/2004 13:41:25 PAGE 2
56 1 // if (debug) printf("ICMP: Sending response to IP layer\n");
57 1
58 1 ip_send(outbuf, ipaddr, ICMP_TYPE, len);
59 1 }
60
61
62 /*
63 //------------------------------------------------------------------------
64 // This builds an outgoing ICMP destination port unreachable response
65 // message. See See "TCP/IP Illustrated, Volume 1" Sect 6.5. This
66 // message is typically sent in response to a UDP message directed
67 // to a port that has no corresponding application running.
68 // Todo: The spec says we should return all options that were in
69 // the original incoming IP header. Right now we cut off everything
70 // after the first 20 bytes.
71 //------------------------------------------------------------------------
72 void dest_unreach_send(UCHAR xdata * inbuf, ULONG ipaddr)
73 {
74 UCHAR xdata * outbuf;
75 ICMP_ERR_HEADER xdata * icmp;
76
77 // Allocate memory for entire outgoing message
78 // including eth and IP haders. Always 70 bytes
79 outbuf = (UCHAR xdata *)malloc(70);
80 if (outbuf == NULL)
81 {
82 // if (debug) printf("ICMP: Oops, out of memory\n");
83 return;
84 }
85
86 icmp = (ICMP_ERR_HEADER xdata *)(outbuf + 34);
87
88 // Fill in ICMP error message header
89 icmp->msg_type = 3; // destination unreachable
90 icmp->msg_code = 3; // port unreachable
91 icmp->checksum = 0;
92
93 // Fill in ICMP error message data
94 icmp->msg_data = 0;
95
96 // Copy in 20 byte original incoming IP header
97 // plus 8 bytes of data
98 memcpy(&icmp->echo_data, inbuf + 14, 28);
99
100 // Compute checksum over the 36 byte long ICMP
101 // header plus data and insert complement
102 icmp->checksum = ~cksum(outbuf + 34, 36);
103
104 // Forward message to the IP layer
105 // if (debug) printf("ICMP: Sending dest unreach to IP layer\n");
106 ip_send(outbuf, ipaddr, ICMP_TYPE, 36);
107 }
108 */
109
110
111
112 //------------------------------------------------------------------------
113 // This handles incoming ICMP messages. See "TCP/IP Illustrated,
114 // Volume 1" Sect 6.2 for discussion of the various ICMP messages
115 //------------------------------------------------------------------------
116 void icmp_rcve(UCHAR xdata * inbuf, UINT len)
117 {
C51 COMPILER V7.06 ICMP 06/26/2004 13:41:25 PAGE 3
118 1 IP_HEADER * ip;
119 1 UCHAR idata msg_type;
120 1 UINT idata temp;
121 1
122 1 // Allow for 14 bytes eth header
123 1 ip = (IP_HEADER *)(inbuf + 14);
124 1
125 1 // IP header has been adjusted if necessary to always be
126 1 // 20 bytes so message starts at an offset of 34
127 1 // Validate checksum of entire ICMP message incl data
128 1 temp = cksum(inbuf + 34, len);
129 1
130 1 if (temp != 0xFFFF)
131 1 {
132 2 // if (debug) printf("ICMP: Error, cksum bad\n");
133 2 return;
134 2 }
135 1
136 1 // Switch on the message type
137 1 msg_type = *(inbuf + 34);
138 1 switch(msg_type)
139 1 {
140 2 case 3:
141 2 // if (debug) printf("ICMP: Dest unreachable rcvd\n");
142 2 break;
143 2
144 2 case 8:
145 2 // if (debug) printf("ICMP: Ping rcvd\n");
146 2 ping_send(inbuf, ip->source_ipaddr, len);
147 2 break;
148 2
149 2 default:
150 2 // if (debug) printf("ICMP: Error, unknown msg rcvd\n");
151 2 break;
152 2 }
153 1 }
154
155
MODULE INFORMATION: STATIC OVERLAYABLE
CODE SIZE = 466 ----
CONSTANT SIZE = ---- ----
XDATA SIZE = ---- 21
PDATA SIZE = ---- ----
DATA SIZE = ---- ----
IDATA SIZE = ---- 3
BIT SIZE = ---- ----
END OF MODULE INFORMATION.
C51 COMPILATION COMPLETE. 0 WARNING(S), 0 ERROR(S)
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