我正在编写客户端服务器应用程序。简单地说,服务器可以为每个客户端使用 UDP 或 TCP。
我希望 TCP 客户端和 UDP 客户端都打印 and 的默认值
SO_SNDBUF
,SO_RCVBUF
但是当我在连接建立之前打印 sndbuf 和 rcvbuf 的默认值时,我很惊讶,值为 0。
注意:我使用的是 Ubuntu 12.10
这是我的代码:
//assume all variables initialized correctly.
/* SO_RCVBUF options */
len = sizeof(rcvbuf);
getsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, &len);
len = sizeof(mss);
getsockopt(sockfd, IPPROTO_TCP, TCP_MAXSEG, &mss, &len);
printf("defaults: SO_RCVBUF = %d, MSS = %d\n", rcvbuf, mss);
rcvbuf = 9973; /* a prime number */
setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf));
len = sizeof(rcvbuf);
getsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, &len);
printf("SO_RCVBUF = %d (after setting it to 9973)\n\n\n\n", rcvbuf);
/* SO_RCVBUF options */
/* SO_SNDBUF options */
len2 = sizeof(sndbuf);
getsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sndbuf, &len2);
//len2 = sizeof(mss2);
getsockopt(sockfd, IPPROTO_TCP, TCP_MAXSEG, &mss2, &len2);
printf("defaults: SO_SNDBUF = %d, MSS = %d\n", sndbuf, mss2);
sndbuf = 9979; /* a prime number */
setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf));
len2 = sizeof(sndbuf);
getsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sndbuf, &len2);
printf("SO_SNDBUF = %d (after setting it to 9979)\n", sndbuf);
/* SO_SNDBUF options */
样本输出:
默认值:SO_RCVBUF = 0,MSS = 0
SO_RCVBUF = 9973(设置为 9973 后)
默认值:SO_SNDBUF = 0,MSS = 0
SO_SNDBUF = 9979(设置为 9979 后)
tcp_time nes411_server
当前时间是(TCP):Mon Apr 22 23:40:46 2013
连接后:
SO_SNDBUF = 170840,MSS = 16384