📄 tcp1.lst
字号:
C51 COMPILER V7.09 TCP1 06/28/2007 09:51:21 PAGE 1
C51 COMPILER V7.09, COMPILATION OF MODULE TCP1
OBJECT MODULE PLACED IN TCP1.obj
COMPILER INVOKED BY: F:\Keil\C51\BIN\C51.EXE tcp\TCP1.C LARGE BROWSE DEBUG OBJECTEXTEND PRINT(.\TCP1.lst) OBJECT(TCP1.ob
-j)
line level source
1 //-----------------------------------------------------------------------------
2 // Copyright (c) 2002 Jim Brady
3 // Do not use commercially without author's permission
4 // Last revised August 2002
5 // Net TCP.C
6 //
7 // This module handles TCP segments
8 // Refer to RFC 793, 896, 1122, 1323, 2018, 2581
9 //
10 // A "connection" is a unique combination of 4 items: His IP address,
11 // his port number, my IP address, and my port number.
12 //
13 // Note that a SYN and a FIN count as a byte of data, but a RST does
14 // not count. Neither do any of the other flags.
15 // See "TCP/IP Illustrated, Volume 1" Sect 17.3 for info on flags
16 //-----------------------------------------------------------------------------
17
18 #include <stdlib.h>
19 #include <ctype.h> // toupper
20 #include "net1.h"
21 #include "cksum.h"
22 #include "serial1.h"
23 #include "ip1.h"
24 #include "http1.h"
25 #include "tcp1.h"
26 #include "utils.h"
27
28
29 // These structures keep track of connection information
30 CONNECTION conxn[5];
31
32 ulong initial_sequence_nr;
33 uint sender_tcpport;
34 static ulong sender_ipaddr;
35 UCHAR just_closed; // Keeps track of when a conxn closed
36
37 extern ulong my_ipaddr;
38 extern UCHAR debug;
39 extern char text[];
40
41 // Options: MSS (4 bytes), NOPS (2 bytes), Selective ACK (2 bytes)
42 UCHAR opt[10] = {
43 0x02, 0x04, 0x05, 0xB4,
44 0x01, 0x01,
45 0x04, 0x02};
46
47
48
49
50 //------------------------------------------------------------------------
51 // Initialize variables declared in this module
52 //
53 //------------------------------------------------------------------------
54 void init_tcp(void)
C51 COMPILER V7.09 TCP1 06/28/2007 09:51:21 PAGE 2
55 {
56 1 memset((char*)conxn, 0, sizeof(conxn));
57 1 just_closed = FALSE;
58 1 initial_sequence_nr = 1;
59 1 }
60
61
62
63 //------------------------------------------------------------------------
64 // This sends a TCP segments that do not include any data.
65 // http_send() in the HTTP module is used to send data.
66 // See "TCP/IP Illustrated, Volume 1" Sect 17.3
67 //------------------------------------------------------------------------
68 //输入参数:
69 //flags: sun,fin,rst,ack等标志以及数据偏移等的设置;
70 //hdr_len: TCP报文首部长度
71 //nr: 连接号
72 //功能：发送不包含任何数据段的TCP报文，比如请求连接或者说释放连接;
73 //http_send发送包含数据段的TCP报文.
74 void tcp_send(uint flags, uint hdr_len, UCHAR nr)
75 {
76 1 ulong sum, dest;
77 1 uint result;
78 1 UCHAR * outbuf;
79 1 TCP_HEADER * tcp;
80 1 IP_HEADER * ip;
81 1
82 1 // Allocate memory for entire outgoing message including
83 1 // eth & IP headers
84 1 //TCP层申请发送缓冲区，包括TCP和IP以及Eth首部
85 1 outbuf = (UCHAR *)malloc(34 + hdr_len); //每次都申请内存，但不释放?
86 1 if (outbuf == NULL)
87 1 {
88 2 // if (debug) serial_send("TCP: Oops, out of memory\n");
89 2 return;
90 2 }
91 1
92 1
93 1 tcp = (TCP_HEADER *)(outbuf + 34); //IP首部20字节
94 1 ip = (IP_HEADER *)(outbuf + 14); //ethernet v2首部14字节
95 1
96 1 // If no connection, then message is probably a reset
97 1 // message which goes back to the sender
98 1 // Otherwise, use information from the connection.
99 1 if (nr == NO_CONNECTION)
100 1 {
101 2 tcp->source_port = HTTP_PORT;
102 2 tcp->dest_port = sender_tcpport;
103 2 tcp->sequence = 0;
104 2 tcp->ack_number = 0;
105 2 dest = sender_ipaddr;
106 2 }
107 1 else if (nr < 5)
108 1 {
109 2 // This message is to connected port
110 2 tcp->source_port = HTTP_PORT; //源端口
111 2 tcp->dest_port = conxn[nr].port; //目的端口
112 2 tcp->sequence = conxn[nr].my_sequence; //序号: 本报文段所发数据的第一个字节的序号
113 2 tcp->ack_number = conxn[nr].his_sequence; //确认号: 期望收到对方的下一个报文段的数据的第一个字节的
-序号
114 2 dest = conxn[nr].ipaddr;
115 2 }
C51 COMPILER V7.09 TCP1 06/28/2007 09:51:21 PAGE 3
116 1 else
117 1 {
118 2 // if (debug) serial_send("TCP: Oops, sock nr out of range\n");
119 2 free(outbuf);
120 2 return;
121 2 }
122 1
123 1 // Total segment length = header length
124 1
125 1 // Insert header len
126 1 tcp->flags = (hdr_len << 10) | flags;
127 1 tcp->window = 1024; //窗口: 用来控制对方发送的数据量.
128 1 tcp->checksum = 0;
129 1 tcp->urgent_ptr = 0; //紧急指针:
130 1
131 1 // Sending SYN with header options
132 1 if (hdr_len == 28)
133 1 {
134 2 memcpy((char*)tcp->options, opt, 8);
135 2 }
136 1
137 1 // Compute checksum including 12 bytes of pseudoheader
138 1 // Must pre-fill 2 items in ip header to do this
139 1 ip->dest_ipaddr = dest;
140 1 ip->source_ipaddr = my_ipaddr;
141 1
142 1 #ifdef __LITTLEENDIAN__
143 1 tcp->flags = ntohs(tcp->flags);
144 1 tcp->window = ntohs(tcp->window);
145 1 tcp->source_port = ntohs(tcp->source_port);
146 1 tcp->sequence = ntohl(tcp->sequence);
147 1 tcp->dest_port = ntohs(tcp->dest_port);
148 1 tcp->ack_number = ntohl(tcp->ack_number);
149 1 ip->source_ipaddr = ntohl(my_ipaddr);
150 1 #endif
151 1
152 1 // Sum source_ipaddr, dest_ipaddr, and entire TCP message
153 1 sum = (ulong)cksum(outbuf + 26, 8 + hdr_len);
154 1
155 1 // Add in the rest of pseudoheader which is
156 1 // protocol id and TCP segment length
157 1 sum += (ulong)0x0006;
158 1 #ifdef __LITTLEENDIAN__
159 1 // hdr_len = ntohs(&hdr_len);
160 1 #endif
161 1 sum += (ulong)hdr_len;
162 1
163 1 // In case there was a carry, add it back around
164 1 result = (uint)(sum + (sum >> 16));
165 1 tcp->checksum = ~result;
166 1
167 1 #ifdef __LITTLEENDIAN__
168 1 tcp->checksum = ntohs(tcp->checksum);
169 1 dest = ntohl(dest);
170 1 // hdr_len = ntohs(&hdr_len);
171 1 #endif
172 1
173 1 // if (debug) serial_send("TCP: Sending msg to IP layer\n");
174 1
175 1 ip_send1(outbuf, dest, TCP_TYPE, hdr_len);
176 1
177 1 #ifdef __LITTLEENDIAN__
C51 COMPILER V7.09 TCP1 06/28/2007 09:51:21 PAGE 4
178 1 free(outbuf);
179 1 #endif
180 1
181 1 // (Re)start TCP retransmit timer
182 1 // conxn[nr].timer = TCP_TIMEOUT; //重发定时器2
183 1 conxn[nr].timer = TCP_TIMEOUT*2;
184 1 }
185
186
187
188
189 //------------------------------------------------------------------------
190 // This runs every 0.5 seconds. If the other end has not ACK'd
191 // everyting we have sent, it re-sends it. To save RAM space, we
192 // regenerate a segment rather than keeping a bunch of segments
193 // hanging around eating up RAM. A connection should not be in an
194 // opening or closing state when this timer expires, so we simply
195 // send a reset.
196 //
197 // If a connection is in the ESTABLISHED state when the timer expires
198 // then we have just sent a web page so re-send the page
199 //------------------------------------------------------------------------
200 void tcp_retransmit(void)
201 {
202 1
203 1 static UCHAR retries = 0;
204 1 UCHAR nr;
205 1
206 1 // Scan through all active connections
207 1 for (nr = 0; nr < 5; nr++)
208 1 {
209 2 if ((conxn[nr].ipaddr != 0) && (conxn[nr].timer))
210 2 {
211 3 // Decrement the timer and see if it hit 0
212 3 conxn[nr].timer--;
213 3 //如果定时器到, 即2秒,
214 3 if (conxn[nr].timer == 0)
215 3 {
216 4 // Socket just timed out. If we are not in ESTABLISHED state
217 4 // something is amiss so send reset and close connection
218 4 //不在Established阶段，发送rst要求，释放连接;
219 4 if (conxn[nr].state != STATE_ESTABLISHED)
220 4 {
221 5 // Send reset and close connection
222 5 // if (debug) serial_send("TCP: Timeout, sending reset\n");
223 5 tcp_send(FLG_RST, 20, nr);
224 5 conxn[nr].ipaddr = 0;
225 5 return;
226 5 }
227 4 else
228 4 {
229 5 // Socket is in ESTABLISHED state. First make sure his
230 5 // ack number is not bogus.
231 5 if (conxn[nr].his_ack > conxn[nr].my_sequence) //如果当前连接的对端确认号大于本端发送号,乱⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -