📄 icmp.lst
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C51 COMPILER V8.01 ICMP 11/23/2005 11:07:35 PAGE 1
C51 COMPILER V8.01, COMPILATION OF MODULE ICMP
OBJECT MODULE PLACED IN Icmp.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE Icmp.c 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 V8.01 ICMP 11/23/2005 11:07:35 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 V8.01 ICMP 11/23/2005 11:07:35 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 = 615 ----
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)
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