I/O多路转接之select
2017-06-30 16:39
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在I/O中，I/O需注意（1）是否有读事件发生
(2)是否有写事件发生
（3）是否有异常事件
进而写出如下代码
select_server.c
1 #include<sys/socket.h>
2 #include<stdio.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include <netinet/in.h>
6 #include <arpa/inet.h>
7 #include<stdlib.h>
8 #include<string.h>
9
10
11 int fds_array[sizeof(fd_set)*8];
12 static void* usage(const char* proc)
13 {
14 printf("usage:%s[local_ip] [local_port]\n",proc);
15 }
16 int starup(const char* ip,int port)
17 {
18 int sock = socket(AF_INET,SOCK_STREAM,0);
19 if(sock < 0)
20 {
21 perror("socket");
22 return 1;
23 }
24
25 struct sockaddr_in local;
26 local.sin_family = AF_INET;
27 local.sin_port = htons(port);
28 local.sin_addr.s_addr = inet_addr(ip);
2 #include<stdio.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include <netinet/in.h>
6 #include <arpa/inet.h>
7 #include<stdlib.h>
8 #include<string.h>
9
10
11 int fds_array[sizeof(fd_set)*8];
12 static void* usage(const char* proc)
13 {
14 printf("usage:%s[local_ip] [local_port]\n",proc);
15 }
16 int starup(const char* ip,int port)
17 {
18 int sock = socket(AF_INET,SOCK_STREAM,0);
19 if(sock < 0)
20 {
21 perror("socket");
22 return 1;
23 }
24
25 struct sockaddr_in local;
26 local.sin_family = AF_INET;
27 local.sin_port = htons(port);
28 local.sin_addr.s_addr = inet_addr(ip);
29 int b=bind(sock,(struct sockaddr*)&local,sizeof(local));
if(b<0)
31 {
32 perror("bind");
33 return 2;
34 }
35
36
37 if(listen(sock,10)<0)
38 {
39 perror("listen");
40 return 3;
41 }
42 return sock;
43 }
44
45 int main(int argc, const char* argv[])
46 {
47 if(argc != 3)
48 {
49 usage(argv[0]);
50 return 4;
51 }
52 int listen_sock = starup(argv[1],atoi(argv[2]));
53 fd_set rfds;
54 fd_set wfds;
FD_ZERO(&rfds);
56 FD_ZERO(&wfds);
57 int i=0;
58 int num = sizeof(fds_array)/sizeof(fds_array[0]);
59 for(; i<num; ++i)//给数组的所有标志位均置为-1
60 {
61 fds_array[i] = -1;
62 }
63 fds_array[0] = listen_sock;
64 while(1)
65 {
66 int maxfd = -1;
67 for(i=0; i<num; i++)
68 {
69 if(fds_array[i]==-1)
70 {
71 continue;
72 }
73 FD_SET(fds_array[i],&rfds);
74 FD_SET(fds_array[i],&wfds);
75 if(maxfd<fds_array[i])
76 {
77 maxfd = fds_array[i];
78 }
79 }
80 switch(select(maxfd+1,&rfds,&wfds,NULL,NULL))
81 {
82 case 0:
83 printf("timeout...\n");
84 break;
85 case -1:
86 perror("select");
87 break;
88 default:
89 { ///at least one read event ready
90 for(i=0; i<num; i++)
91 {
92 struct sockaddr_in client;
93 socklen_t len = sizeof(client);
94 if(fds_array[i]<0)
95 {
96 continue;
97 }
98 if(i==0 && FD_ISSET(listen_sock,&rfds))
99 {
100 int new_sock = accept(listen_sock,\
101 (struct sockaddr*)&client,&len);
102 if(new_sock<0)
103 {
104 perror("accept");
105 continue;
106 }
107 printf("get a client [%s:%d]\n",inet_ntoa(client.sin_addr),ntohs(client.sin_port));
108 int j=0;
109 for(;j<num; j++)
110 {
111 if(fds_array[j]<0)
112 {
113 break;
114 }
115 }
116 if(j==num)
117 {
118 printf("fd_set full\n");
119 close(new_sock);
120 }
121 else
122 {
123 fds_array[j] = new_sock;
124 }
125 }
126 else if(i!=0 &&( FD_ISSET(fds_array[i],&rfds)||(FD_ISSET(fds_array[i],&wfds))))
127 {
128 char buf[1024];
129 if(FD_ISSET(fds_array[i],&rfds))
130 {
131 ssize_t s= read(fds_array[i],buf,sizeof(buf)-1);
132 if(s>0)
133 {
134 buf[s]=0;
135 printf("client#%s\n",buf);
136
137 if(FD_ISSET(fds_array[i],&wfds))
138 {
139 printf("please enter:");
140 fflush(stdout);
141 ssize_t r = read(0,buf,sizeof(buf)-1);
if(r>0)
143 {
144 buf[r] = 0;
145 ssize_t w = write(fds_array[i],buf,strlen(buf));
146 if(w>0)
147 {
148 buf[w] = 0;
149 printf("server echo:%s\n",buf);
150 }
151 else if(w==0)
152 {
153 printf("no data enter\n");
154 close(fds_array[i]);
155 fds_array[i] = -1;
156 }
157 else
158 {
159 printf("server error\n");
160 close(fds_array[i]);
161 fds_array[i] = -1;
162 }
163 }
164 }
165 }
166 else if(s==0)
{
168 printf("client is quit\n");
169 close(fds_array[i]);
170
171 fds_array[i] = -1;
172 }
173 else
174 {
175 printf("client error\n");
176 close(fds_array[i]);
177
178 fds_array[i] = -1;
179 }
180 }
181
182 }
183 else{
184
185 }
186 }
187 }
188 break;
189 }
190
191 }
192
193 }
select_client.c
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<unistd.h>
4 #include<sys/types.h>
5 #include<sys/socket.h>
6 #include<arpa/inet.h>
7 #include<netinet/in.h>
8 #include<string.h>
9 #include<sys/stat.h>
10 #include<fcntl.h>
11
12
13 static void usage(const char* proc)
14 {
15 printf("usage:%s [local_ip] [local_proc]\n",proc);
16 }
17
18 int main(int argc,char* argv[])
19 {
20 if(argc!=3){
21 usage(argv[0]);
22 exit(1);
23 }
24
25 int sock = socket(AF_INET,SOCK_STREAM,0);
26
27 struct sockaddr_in server;
28 server.sin_family = AF_INET;
29 server.sin_port = htons(atoi(argv[2]));
30 server.sin_addr.s_addr = inet_addr(argv[1]);
31
32 if(connect(sock,(struct sockaddr*)&server,sizeof(server))<0){
33 perror("connect");
34 exit(2);
35 }
36
37 char buf[1024];
38 while(1){
39 printf("please enter#");
40 fflush(stdout);
41
42 int sfd = dup(1);
43 close(1);
44 dup2(sock,1);
45 ssize_t s = read(0,buf,sizeof(buf)-1);
46 printf("%s",buf);
47 dup2(sfd,STDOUT_FILENO);
48
49 s = read(sock,buf,sizeof(buf)-1);
50 buf[s] = 0;
51 printf("server# %s",buf);
52 }
53 return 0;
54 }
运行解果：
(2)是否有写事件发生
（3）是否有异常事件
进而写出如下代码
select_server.c
1 #include<sys/socket.h>
2 #include<stdio.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include <netinet/in.h>
6 #include <arpa/inet.h>
7 #include<stdlib.h>
8 #include<string.h>
9
10
11 int fds_array[sizeof(fd_set)*8];
12 static void* usage(const char* proc)
13 {
14 printf("usage:%s[local_ip] [local_port]\n",proc);
15 }
16 int starup(const char* ip,int port)
17 {
18 int sock = socket(AF_INET,SOCK_STREAM,0);
19 if(sock < 0)
20 {
21 perror("socket");
22 return 1;
23 }
24
25 struct sockaddr_in local;
26 local.sin_family = AF_INET;
27 local.sin_port = htons(port);
28 local.sin_addr.s_addr = inet_addr(ip);
2 #include<stdio.h>
3 #include<sys/types.h>
4 #include<sys/socket.h>
5 #include <netinet/in.h>
6 #include <arpa/inet.h>
7 #include<stdlib.h>
8 #include<string.h>
9
10
11 int fds_array[sizeof(fd_set)*8];
12 static void* usage(const char* proc)
13 {
14 printf("usage:%s[local_ip] [local_port]\n",proc);
15 }
16 int starup(const char* ip,int port)
17 {
18 int sock = socket(AF_INET,SOCK_STREAM,0);
19 if(sock < 0)
20 {
21 perror("socket");
22 return 1;
23 }
24
25 struct sockaddr_in local;
26 local.sin_family = AF_INET;
27 local.sin_port = htons(port);
28 local.sin_addr.s_addr = inet_addr(ip);
29 int b=bind(sock,(struct sockaddr*)&local,sizeof(local));
if(b<0)
31 {
32 perror("bind");
33 return 2;
34 }
35
36
37 if(listen(sock,10)<0)
38 {
39 perror("listen");
40 return 3;
41 }
42 return sock;
43 }
44
45 int main(int argc, const char* argv[])
46 {
47 if(argc != 3)
48 {
49 usage(argv[0]);
50 return 4;
51 }
52 int listen_sock = starup(argv[1],atoi(argv[2]));
53 fd_set rfds;
54 fd_set wfds;
FD_ZERO(&rfds);
56 FD_ZERO(&wfds);
57 int i=0;
58 int num = sizeof(fds_array)/sizeof(fds_array[0]);
59 for(; i<num; ++i)//给数组的所有标志位均置为-1
60 {
61 fds_array[i] = -1;
62 }
63 fds_array[0] = listen_sock;
64 while(1)
65 {
66 int maxfd = -1;
67 for(i=0; i<num; i++)
68 {
69 if(fds_array[i]==-1)
70 {
71 continue;
72 }
73 FD_SET(fds_array[i],&rfds);
74 FD_SET(fds_array[i],&wfds);
75 if(maxfd<fds_array[i])
76 {
77 maxfd = fds_array[i];
78 }
79 }
80 switch(select(maxfd+1,&rfds,&wfds,NULL,NULL))
81 {
82 case 0:
83 printf("timeout...\n");
84 break;
85 case -1:
86 perror("select");
87 break;
88 default:
89 { ///at least one read event ready
90 for(i=0; i<num; i++)
91 {
92 struct sockaddr_in client;
93 socklen_t len = sizeof(client);
94 if(fds_array[i]<0)
95 {
96 continue;
97 }
98 if(i==0 && FD_ISSET(listen_sock,&rfds))
99 {
100 int new_sock = accept(listen_sock,\
101 (struct sockaddr*)&client,&len);
102 if(new_sock<0)
103 {
104 perror("accept");
105 continue;
106 }
107 printf("get a client [%s:%d]\n",inet_ntoa(client.sin_addr),ntohs(client.sin_port));
108 int j=0;
109 for(;j<num; j++)
110 {
111 if(fds_array[j]<0)
112 {
113 break;
114 }
115 }
116 if(j==num)
117 {
118 printf("fd_set full\n");
119 close(new_sock);
120 }
121 else
122 {
123 fds_array[j] = new_sock;
124 }
125 }
126 else if(i!=0 &&( FD_ISSET(fds_array[i],&rfds)||(FD_ISSET(fds_array[i],&wfds))))
127 {
128 char buf[1024];
129 if(FD_ISSET(fds_array[i],&rfds))
130 {
131 ssize_t s= read(fds_array[i],buf,sizeof(buf)-1);
132 if(s>0)
133 {
134 buf[s]=0;
135 printf("client#%s\n",buf);
136
137 if(FD_ISSET(fds_array[i],&wfds))
138 {
139 printf("please enter:");
140 fflush(stdout);
141 ssize_t r = read(0,buf,sizeof(buf)-1);
if(r>0)
143 {
144 buf[r] = 0;
145 ssize_t w = write(fds_array[i],buf,strlen(buf));
146 if(w>0)
147 {
148 buf[w] = 0;
149 printf("server echo:%s\n",buf);
150 }
151 else if(w==0)
152 {
153 printf("no data enter\n");
154 close(fds_array[i]);
155 fds_array[i] = -1;
156 }
157 else
158 {
159 printf("server error\n");
160 close(fds_array[i]);
161 fds_array[i] = -1;
162 }
163 }
164 }
165 }
166 else if(s==0)
{
168 printf("client is quit\n");
169 close(fds_array[i]);
170
171 fds_array[i] = -1;
172 }
173 else
174 {
175 printf("client error\n");
176 close(fds_array[i]);
177
178 fds_array[i] = -1;
179 }
180 }
181
182 }
183 else{
184
185 }
186 }
187 }
188 break;
189 }
190
191 }
192
193 }
select_client.c
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<unistd.h>
4 #include<sys/types.h>
5 #include<sys/socket.h>
6 #include<arpa/inet.h>
7 #include<netinet/in.h>
8 #include<string.h>
9 #include<sys/stat.h>
10 #include<fcntl.h>
11
12
13 static void usage(const char* proc)
14 {
15 printf("usage:%s [local_ip] [local_proc]\n",proc);
16 }
17
18 int main(int argc,char* argv[])
19 {
20 if(argc!=3){
21 usage(argv[0]);
22 exit(1);
23 }
24
25 int sock = socket(AF_INET,SOCK_STREAM,0);
26
27 struct sockaddr_in server;
28 server.sin_family = AF_INET;
29 server.sin_port = htons(atoi(argv[2]));
30 server.sin_addr.s_addr = inet_addr(argv[1]);
31
32 if(connect(sock,(struct sockaddr*)&server,sizeof(server))<0){
33 perror("connect");
34 exit(2);
35 }
36
37 char buf[1024];
38 while(1){
39 printf("please enter#");
40 fflush(stdout);
41
42 int sfd = dup(1);
43 close(1);
44 dup2(sock,1);
45 ssize_t s = read(0,buf,sizeof(buf)-1);
46 printf("%s",buf);
47 dup2(sfd,STDOUT_FILENO);
48
49 s = read(sock,buf,sizeof(buf)-1);
50 buf[s] = 0;
51 printf("server# %s",buf);
52 }
53 return 0;
54 }
运行解果：
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