📄 tcp.lst
字号:
C51 COMPILER V7.06 TCP 06/26/2004 13:41:26 PAGE 1
C51 COMPILER V7.06, COMPILATION OF MODULE TCP
OBJECT MODULE PLACED IN TCP.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE TCP.C LARGE BROWSE DEBUG OBJECTEXTEND
stmt level source
1
2 #include <string.h>
3 #include <stdlib.h>
4 #include <ctype.h> // toupper
5 #include <reg89C58.h>
6 #include <stdio.h>
7 #include "net.h"
8 #include "cksum.h"
9 #include "ip.h"
10 #include "tcp.h"
11
12
13 // These structures keep track of connection information
14 CONNECTION xdata conxn[5];
15
16 ULONG idata initial_sequence_nr;
17 UINT xdata sender_tcpport;
18 static ULONG xdata sender_ipaddr;
19 UCHAR idata just_closed; // Keeps track of when a conxn closed
20
21 extern ULONG data my_ipaddr;
22 extern UCHAR idata debug;
23 extern char xdata text[];
24
25 // Options: MSS (4 bytes), NOPS (2 bytes), Selective ACK (2 bytes)
26 UCHAR code opt[10] = {
27 0x02, 0x04, 0x05, 0xB4,
28 0x01, 0x01,
29 0x04, 0x02};
30
31
32
33 //------------------------------------------------------------------------
34 // Initialize variables declared in this module
35 //
36 //------------------------------------------------------------------------
37 void init_tcp(void)
38 {
39 1 memset(conxn, 0, sizeof(conxn));
40 1 just_closed = FALSE;
41 1 initial_sequence_nr = 1;
42 1 }
43
44
45
46 //------------------------------------------------------------------------
47 // This sends a TCP segments that do not include any data.
48 // http_send() in the HTTP module is used to send data.
49 // See "TCP/IP Illustrated, Volume 1" Sect 17.3
50 //------------------------------------------------------------------------
51 void tcp_send(UINT flags, UINT hdr_len, UCHAR nr)
52 {
53 1 ULONG idata sum, dest;
54 1 UINT idata result;
55 1 UCHAR xdata * outbuf;
C51 COMPILER V7.06 TCP 06/26/2004 13:41:26 PAGE 2
56 1 TCP_HEADER xdata * tcp;
57 1 IP_HEADER xdata * ip;
58 1
59 1
60 1 // Allocate memory for entire outgoing message including
61 1 // eth & IP headers
62 1 outbuf = (UCHAR xdata *)malloc(34 + hdr_len);
63 1 if (outbuf == NULL)
64 1 {
65 2 // if (debug) printf("TCP: Oops, out of memory\n");
66 2 return;
67 2 }
68 1
69 1
70 1 tcp = (TCP_HEADER xdata *)(outbuf + 34);
71 1 ip = (IP_HEADER xdata *)(outbuf + 14);
72 1
73 1 // If no connection, then message is probably a reset
74 1 // message which goes back to the sender
75 1 // Otherwise, use information from the connection.
76 1 if (nr == NO_CONNECTION)
77 1 {
78 2 tcp->source_port = HTTP_PORT;
79 2 tcp->dest_port = sender_tcpport;
80 2 tcp->sequence = 0;
81 2 tcp->ack_number = 0;
82 2 dest = sender_ipaddr;
83 2 }
84 1 else if (nr < 5)
85 1 {
86 2 // This message is to connected port
87 2 tcp->source_port = HTTP_PORT;
88 2 tcp->dest_port = conxn[nr].port;
89 2 tcp->sequence = conxn[nr].my_sequence;
90 2 tcp->ack_number = conxn[nr].his_sequence;
91 2 dest = conxn[nr].ipaddr;
92 2 }
93 1 else
94 1 {
95 2 // if (debug) printf("TCP: Oops, sock nr out of range\n");
96 2 free(outbuf);
97 2 return;
98 2 }
99 1
100 1 // Total segment length = header length
101 1
102 1 // Insert header len
103 1 tcp->flags = (hdr_len << 10) | flags;
104 1 tcp->window = 1024;
105 1 tcp->checksum = 0;
106 1 tcp->urgent_ptr = 0;
107 1
108 1 // Sending SYN with header options
109 1 if (hdr_len == 28)
110 1 {
111 2 memcpy(&tcp->options, opt, 8);
112 2 }
113 1
114 1 // Compute checksum including 12 bytes of pseudoheader
115 1 // Must pre-fill 2 items in ip header to do this
116 1 ip->dest_ipaddr = dest;
117 1 ip->source_ipaddr = my_ipaddr;
C51 COMPILER V7.06 TCP 06/26/2004 13:41:26 PAGE 3
118 1
119 1 // Sum source_ipaddr, dest_ipaddr, and entire TCP message
120 1 sum = (ULONG)cksum(outbuf + 26, 8 + hdr_len);
121 1
122 1 // Add in the rest of pseudoheader which is
123 1 // protocol id and TCP segment length
124 1 sum += (ULONG)0x0006;
125 1 sum += (ULONG)hdr_len;
126 1
127 1 // In case there was a carry, add it back around
128 1 result = (UINT)(sum + (sum >> 16));
129 1 tcp->checksum = ~result;
130 1
131 1 // if (debug) printf("TCP: Sending msg to IP layer\n");
132 1 ip_send(outbuf, dest, TCP_TYPE, hdr_len);
133 1
134 1 // (Re)start TCP retransmit timer
135 1 conxn[nr].timer = TCP_TIMEOUT;
136 1 }
137
138
139
140
141 //------------------------------------------------------------------------
142 // This runs every 0.5 seconds. If the other end has not ACK'd
143 // everyting we have sent, it re-sends it. To save RAM space, we
144 // regenerate a segment rather than keeping a bunch of segments
145 // hanging around eating up RAM. A connection should not be in an
146 // opening or closing state when this timer expires, so we simply
147 // send a reset.
148 //
149 // If a connection is in the ESTABLISHED state when the timer expires
150 // then we have just sent a web page so re-send the page
151 //------------------------------------------------------------------------
152 void tcp_retransmit(void)
153 {
154 1 static UCHAR idata retries = 0;
155 1 UCHAR idata nr;
156 1
157 1 // Scan through all active connections
158 1 for (nr = 0; nr < 5; nr++)
159 1 {
160 2 if ((conxn[nr].ipaddr != 0) && (conxn[nr].timer))
161 2 {
162 3 // Decrement the timer and see if it hit 0
163 3 conxn[nr].timer--;
164 3 if (conxn[nr].timer == 0)
165 3 {
166 4 // Socket just timed out. If we are not in ESTABLISHED state
167 4 // something is amiss so send reset and close connection
168 4 if (conxn[nr].state != STATE_ESTABLISHED)
169 4 {
170 5 // Send reset and close connection
171 5 // if (debug) printf("TCP: Timeout, sending reset\n");
172 5 tcp_send(FLG_RST, 20, nr);
173 5 conxn[nr].ipaddr = 0;
174 5 return;
175 5 }
176 4 else
177 4 {
178 5 // Socket is in ESTABLISHED state. First make sure his
179 5 // ack number is not bogus.
C51 COMPILER V7.06 TCP 06/26/2004 13:41:26 PAGE 4
180 5 if (conxn[nr].his_ack > conxn[nr].my_sequence)
181 5 {
182 6 // Send reset and close connection
183 6 // if (debug) printf("TCP: Timeout, sending reset\n");
184 6 tcp_send(FLG_RST, 20, nr);
185 6 conxn[nr].ipaddr = 0;
186 6 return;
187 6 }
188 5
189 5 // We always increment our sequence number immediately
190 5 // after sending, so the ack number from the other end
191 5 // should be equal to our sequence number. If it is less,
192 5 // it means he lost some of our data.
193 5 if (conxn[nr].his_ack < conxn[nr].my_sequence)
194 5 {
195 6 retries++;
196 6 if (retries <= 2)
197 6 {
198 7 // The only thing we send is a web page, and it looks
199 7 // like other end did not get it, so resend
200 7 // but do not increase my sequence number
201 7 // if (debug) printf("TCP: Timeout, resending data\n");
202 7 // http_server(conxn[nr].query, 0, nr, 1);
203 7 // conxn[nr].inactivity = INACTIVITY_TIME;
204 7 }
205 6 else
206 6 {
207 7 // if (debug) printf("TCP: Giving up, sending reset\n");
208 7 // Send reset and close connection
209 7 tcp_send(FLG_RST, 20, nr);
210 7 conxn[nr].ipaddr = 0;
211 7 }
212 6 }
213 5 }
214 4 }
215 3 }
216 2 }
217 1 }
⌨️ 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 + -