📄 icmp.lst
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C51 COMPILER V7.20 ICMP 03/07/2006 14:49:10 PAGE 1
C51 COMPILER V7.20, 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 // 处理ICMP报文
7 //-----------------------------------------------------------------------------
8 #include <string.h>
9 #include <stdlib.h>
10 #include "reg52.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 // 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 // PING的返回信息。返回MAC和IP头。
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) SendCommString("PING: Oops, out of memory\r");
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;//回显应答
45 1 ping_out->msg_code = 0;//代码0
46 1 ping_out->checksum = 0;//校验和
47 1 ping_out->identifier = ping_in->identifier;//标识符，这两个是传送过来的数据
48 1 ping_out->sequence = ping_in->sequence;//序列号字段
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 //校验
55 1 ping_out->checksum = ~cksum(outbuf + 34, len);
C51 COMPILER V7.20 ICMP 03/07/2006 14:49:10 PAGE 2
56 1
57 1 if (debug) SendCommString("ICMP: Sending response to IP layer\r");
58 1
59 1 ip_send(outbuf, ipaddr, ICMP_TYPE, len);
60 1 }
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 // 发送一个未到达信息，这个消息主要用于回应一个UDP信息，如果没有对应的端口。
72 //------------------------------------------------------------------------
73 void dest_unreach_send(UCHAR xdata * inbuf, ULONG ipaddr)
74 {
75 1 UCHAR xdata * outbuf;
76 1 ICMP_ERR_HEADER xdata * icmp;
77 1
78 1 // Allocate memory for entire outgoing message
79 1 // including eth and IP haders. Always 70 bytes
80 1 outbuf = (UCHAR xdata *)malloc(70);
81 1 if (outbuf == NULL)
82 1 {
83 2 if (debug) SendCommString("ICMP: Oops, out of memory\r");
84 2 return;
85 2 }
86 1
87 1 icmp = (ICMP_ERR_HEADER xdata *)(outbuf + 34);
88 1
89 1 // Fill in ICMP error message header
90 1 icmp->msg_type = 3; // destination unreachable目的地址不对
91 1 icmp->msg_code = 3; // port unreachable端口未到达
92 1 icmp->checksum = 0;
93 1
94 1 // Fill in ICMP error message data
95 1 icmp->msg_data = 0;
96 1
97 1 // Copy in 20 byte original incoming IP header
98 1 // plus 8 bytes of data
99 1 memcpy(&icmp->echo_data, inbuf + 14, 28);
100 1
101 1 // Compute checksum over the 36 byte long ICMP
102 1 // header plus data and insert complement
103 1 icmp->checksum = ~cksum(outbuf + 34, 36);
104 1
105 1 // Forward message to the IP layer
106 1 if (debug) SendCommString("ICMP: Sending dest unreach to IP layer\r");
107 1 ip_send(outbuf, ipaddr, ICMP_TYPE, 36);
108 1 }
109
110 //------------------------------------------------------------------------
111 // This handles incoming ICMP messages. See "TCP/IP Illustrated,
112 // Volume 1" Sect 6.2 for discussion of the various ICMP messages
113 // 处理收到的ICMP信息
114 //------------------------------------------------------------------------
115 void icmp_rcve(UCHAR xdata * inbuf, UINT len)
116 {
117 1 IP_HEADER * ip;
C51 COMPILER V7.20 ICMP 03/07/2006 14:49:10 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) SendCommString("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);//消息类型
137 1 switch(msg_type)
138 1 {
139 2 case 3://目的地址未到达
140 2 if (debug) SendCommString("ICMP: Dest unreachable rcvd\r");
141 2 break;
142 2
143 2 case 8://收到，对方要求请求回显
144 2 if (debug) SendCommString("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) SendCommString("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)
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