TCP套接字编程常用函数

#include <sys/socket.h>

int socket(int family, int type, int protocol);   // 调用成功返回非负的套接字描述符，出错返回-1

#include <sys/socket.h>

int connect(int sockfd, const struct sockaddr *servaddr, socklen_t addrlen);   // 调用成功返回0，出错返回-1

#include <sys/socket.h>

int bind(int sockfd, const struct sockaddr *myaddr, socklen_t addrlen);   // 调用成功返回0，出错返回-1

#include <sys/socket.h>

int listen(int sockfd, int backlog);   // 调用成功返回0，出错返回-1

#include <sys/socket.h>

// cliaddr、addrlen用于返回已连接对端进程(客户)的协议地址
// 调用成功返回非负描述符，出错返回-1
int accept(int sockfd, struct sockaddr *cliaddr, socklen_t *addrlen);  

#include <unistd.h>

int close(int sockfd);     // 调用成功返回0，出错返回-1

#include <sys/socket.h>

int getsockname(int sockfd, struct sockaddr *localaddr, socklen_t *addrlen);   // 调用成功返回0，出错返回-1

int getpeername(int sockfd, struct sockaddr *peeraddr, socklen_t *addrlen);    // 调用成功返回0，出错返回-1

#include <sys/socket.h>

// 调用成功返回0，出错返回-1
int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen);       

// 调用成功返回0，出错返回-1
int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen);   

 1 #include "net.h"
 2 
 3 #define SA struct sockaddr
 4 
 5 int main(int argc, char **argv)
 6 {
 7     int sockfd, n;
 8     char recvline[MAXLINE + 1];
 9     struct sockaddr_in servaddr;
10 
11     if (argc != 2)
12     {
13         printf("Error: Options!\n");
14           return -1;
15     }
16 
17     if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
18     {
19         printf("Error: Socket!\n");
20           return -1;
21     }
22 
23     bzero(&servaddr, sizeof(servaddr));
24     servaddr.sin_family = AF_INET;
25     servaddr.sin_port = htons(13);
26 
27     if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
28     {
29         printf("Error: inet_pton for %s\n", argv[1]);
30                 return -1;
31     }
32 
33     if (connect(sockfd, (SA *) &servaddr, sizeof(servaddr)) < 0)
34     {
35         printf("Error: Connect!\n");
36     }
37 
38     while ( (n = read(sockfd, recvline, MAXLINE)) > 0 )
39     {
40         recvline[n] = ‘\0‘;   
41 
42               if (fputs(recvline, stdout) == EOF)
43               {
44                         printf("Error: Fputs!\n");
45               }
46     }
47 
48     if (n < 0)
49     {
50         printf("Erroe: Read!\n");
51     }
52 
53     return 0;
54 }

 1 #include "net.h"
 2 
 3 #define SA struct sockaddr
 4 
 5 int main(int argc, char **argv)
 6 {
 7     int listenfd, connfd;
 8     struct sockaddr_in servaddr;
 9     char buff[MAXLINE];
10     time_t ticks;
11 
12     if ( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
13     {
14         printf("Error: Socket!\n");
15                 return -1;
16     }
17 
18     bzero(&servaddr, sizeof(servaddr));
19     servaddr.sin_family = AF_INET;
20     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
21     servaddr.sin_port = htons(13);
22 
23     if (bind(listenfd, (SA *) &servaddr, sizeof(servaddr)) < 0)
24     {
25         printf("Error: Bind!\n");
26                 return -1;
27     }
28 
29     if (listen(listenfd, LISTENQ) < 0)
30     {
31         printf("Error: Listen!\n");
32                 return -1;
33     }
34 
35     for ( ; ; )
36     {
37         if ( (connfd = accept(listenfd, (SA *) NULL, NULL)) < 0 )
38         {
39             printf("Error: Accept!\n");
40             return -1;
41         }
42 
43                 ticks = time(NULL);
44                 snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
45 
46                 if (write(connfd, buff, strlen(buff)) < 0)
47                 {
48                     printf("Error: Write!\n");
49                     return -1;
50                 }
51 
52                 if (close(connfd) < 0)
53                 {
54                     printf("Error: Close!\n");
55                     return -1;
56                 }
57     }
58 
59     return 0;
60 }