Linux setsockopt和getsockopt函数的用法分析

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我是靠谱客的博主大胆寒风，最近开发中收集的这篇文章主要介绍Linux setsockopt和getsockopt函数的用法分析，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

套接字机制提供两个套接字选项来控制套接字行为。一个接口用来控制选项，另一个接口允许查询一个选项的状态。

1 #include <sys/types.h>
2 #include <sys/socket.h>
3
4 int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen);
5 int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen);
6 返回值：若成功则返回0，若出错则返回-1

参数说明：

sockfd:必须指向一个打开的套接字描述符。

level:标识了选项应用的协议。

optname:要设置或获取套接字选项的名字。

optval:指向函数设置或获取值得地址，即保存选项值的缓存区。

optlen:指定了optval指向的对象的大小。

示例1：使用选项SO_RCVBUF和SO_SNDBUF获取缓冲区大小

server.c

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<sys/types.h>
 4 #include<sys/socket.h>
 5 #include<unistd.h>
 6 #include<arpa/inet.h>
 7 #include<netinet/in.h>
 8 #include<string.h>
 9 #include<errno.h>
10
11 #define N 64
12 #define err_log(log) do{ perror(log); exit(1);}while(0)
13
14 int main(int argc, const char *argv[])
15 {
16
int sockfd, connectfd;
17
char buf[N];
18
struct sockaddr_in serveraddr, clientaddr;
19
int optval;
20
socklen_t optlen = sizeof(optval);
21
socklen_t len = sizeof(clientaddr);
22
23
if(argc != 3)
24 
{
25
fprintf(stderr, "Usage:%s serverip port", argv[0]);
26
return -1;
27 
}
28
sockfd = socket(AF_INET, SOCK_STREAM, 0);
29
if(sockfd < 0)
30
err_log("fail to sockfd");
31
32
serveraddr.sin_family = AF_INET;
33
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
34
serveraddr.sin_port = htons(atoi(argv[2]));
35
36
if(getsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &optval, &optlen) < 0)
37
err_log("fail to getsockopt");
38
printf("SO_SNDBUF:%d Kn", optval/1024);
39
40
if(getsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &optval, &optlen) < 0)
41
err_log("fail to getsockopt");
42
printf("SO_RCVBUF:%d Kn", optval/1024);
43
44
if(bind(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0)
45
err_log("fail to bind");
46
if(listen(sockfd, 5) < 0)
47
err_log("fail to listen");
48
if((connectfd = accept(sockfd, (struct sockaddr*)&clientaddr, &len)) < 0)
49
err_log("fail to connectfd");
50
51
printf("client:%s--->%dn", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
52
53
while(1)
54 
{
55
if(recv(connectfd, buf, N, 0) < 0)
56
err_log("fail to recv");
57
if(strncmp(buf, "quit", 4) == 0)
58
break;
59
buf[strlen(buf) - 1] = '';
60
printf("buf:%sn", buf);
61
strcat(buf, "+++***---");
62
if(send(connectfd, buf, N, 0) < 0)
63
err_log("fail to send");
64 
}
65 
close(connectfd);
66 
close(sockfd);
67
return 0;
68 }

client.c

 1 #include<stdio.h>
 2 #include<sys/types.h>
 3 #include<sys/socket.h>
 4 #include<unistd.h>
 5 #include<arpa/inet.h>
 6 #include<netinet/in.h>
 7 #include<string.h>
 8 #include<stdlib.h>
 9 #include<errno.h>
10
11 #define N 64
12 #define err_log(log) do{perror(log); exit(1);}while(0)
13
14 int main(int argc, const char *argv[])
15 {
16
int sockfd;
17
struct sockaddr_in serveraddr;
18
char buf[N];
19
20
if(argc != 3)
21 
{
22
fprintf(stderr, "Usage:%s serverip port.", argv[1]);
23
return -1;
24 
}
25
sockfd = socket(AF_INET, SOCK_STREAM, 0);
26
if(sockfd < 0)
27
err_log("fail to sockfd");
28
29
serveraddr.sin_family = AF_INET;
30
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
31
serveraddr.sin_port = htons(atoi(argv[2]));
32
if(connect(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0)
33
err_log("fail to connect");
34
35
while(1)
36 
{
37
printf("<client>");
38 
fgets(buf, N, stdin);
39
if(send(sockfd, buf, N, 0) < 0)
40
err_log("fail to send");
41
if(strncmp(buf, "quit", 4) == 0)
42
break;
43
if(recv(sockfd, buf, N, 0) < 0)
44
err_log("fail to recv");
45
printf("buf:%sn", buf);
46 
}
47 
close(sockfd);
48
return 0;
49 }

服务器运行结果：

客户端运行结果：

示例2：使用选项SO_RCVTIMEO超时接收

server.c

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<sys/types.h>
 4 #include<sys/socket.h>
 5 #include<unistd.h>
 6 #include<netinet/in.h>
 7 #include<arpa/inet.h>
 8 #include<string.h>
 9 #include<errno.h>
10
11 #define N 64
12 #define err_log(log) do{ perror(log); exit(1);}while(0)
13
14 int main(int argc, const char *argv[])
15 {
16
int sockfd, connectfd;
17
char buf[N];
18
struct sockaddr_in serveraddr, clientaddr;
19
socklen_t len = sizeof(clientaddr);
20
struct timeval tv;
21
socklen_t optlen = sizeof(tv);
22
23
if(argc != 3)
24 
{
25
fprintf(stderr, "Usage:%s serverip port", argv[0]);
26
return -1;
27 
}
28
29
sockfd = socket(AF_INET, SOCK_STREAM, 0);
30
if(sockfd < 0)
31
err_log("fail to sockfd");
32
33
serveraddr.sin_family = AF_INET;
34
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
35
serveraddr.sin_port = htons(atoi(argv[2]));
36
37
tv.tv_sec = 5;
38
tv.tv_usec = 0;
39
if(setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, optlen) < 0)
40
err_log("fail to setsockopt");
41
42
if(bind(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0)
43
err_log("fail to bind");
44
45
if(listen(sockfd, 5) < 0)
46
err_log("fail to listen");
47
48
if((connectfd = accept(sockfd, (struct sockaddr*)&clientaddr, &len)) < 0)
49 
{
50
if(errno == 11)
51 
{
52
printf("errno = %d--->%sn", errno, strerror(errno));
53 
}
54
else
55 
{
56
err_log("fail to accept");
57 
}
58 
}
59
printf("client:%s--->%dn", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
60
while(1)
61 
{
62
if(recv(connectfd, buf, N, 0) < 0)
63
err_log("fail to recv");
64
if(strncmp(buf, "quit", 4) == 0)
65
break;
66
buf[strlen(buf) - 1] = '';
67
printf("buf:%sn", buf);
68 
}
69 
close(connectfd);
70 
close(sockfd);
71
return 0;
72 }

client.c

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<sys/types.h>
 4 #include<sys/socket.h>
 5 #include<unistd.h>
 6 #include<arpa/inet.h>
 7 #include<netinet/in.h>
 8 #include<string.h>
 9 #include<errno.h>
10
11 #define N 64
12 #define err_log(log) do{perror(log); exit(1);}while(0)
13
14 int main(int argc, const char *argv[])
15 {
16
int sockfd;
17
char buf[N];
18
struct sockaddr_in serveraddr;
19
20
if(argc != 3)
21 
{
22
fprintf(stderr, "Usage:%s serverip port.", argv[0]);
23
return -1;
24 
}
25
26
sockfd = socket(AF_INET, SOCK_STREAM, 0);
27
if(sockfd < 0)
28
err_log("fail to sockfd");
29
30
serveraddr.sin_family = AF_INET;
31
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
32
serveraddr.sin_port = htons(atoi(argv[2]));
33
34
if(connect(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0)
35
err_log("fail to connect");
36
37
while(1)
38 
{
39
printf("<client>");
40 
fgets(buf, N, stdin);
41
if(send(sockfd, buf, N, 0) < 0)
42
err_log("fail to send");
43
if(strncmp(buf, "quit", 4) == 0)
44
break;
45 
}
46 
close(sockfd);
47
return 0;
48 }