C语言 SOL_SOCKET 有什么用？
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What is SOL_SOCKET used for?
提问by Blake
As it is stated in the Linux manpage
正如 Linuxman页面中所述
Use this constant as the level argument to
getsockoptorsetsockoptto manipulate the socket-level options described in this section
使用此常量作为级别参数
getsockopt或setsockopt操作本节中描述的套接字级别选项
But I don't get this explanation. What is the purpose of SOL_SOCKET? What does it do?
但我不明白这个解释。的目的是SOL_SOCKET什么？它有什么作用？
采纳答案by demo.b
回答by jspacek
When retrieving a socket option, or setting it, you specify the option name as well as the level. When level = SOL_SOCKET, the item will be searched for in the socket itself.
在检索或设置套接字选项时，您需要指定选项名称和级别。当 level = 时SOL_SOCKET，将在套接字本身中搜索该项目。
For example, suppose we want to set the socket option to reuse the address to 1 (on/true), we pass in the "level" SOL_SOCKETand the value we want it set to.
例如，假设我们想将套接字选项设置为重用地址为 1（on/true），我们传入“级别”SOL_SOCKET和我们希望它设置的值。
int value = 1;
setsockopt(mysocket, SOL_SOCKET, SO_REUSEADDR, &value, sizeof(value));
This will set the SO_REUSEADDRin my socket to 1.
这会将SO_REUSEADDR我的套接字中的设置为 1。
I was stuck on this myself, the documentation is extremely cryptic. Slightly more detailed documentation here: http://pubs.opengroup.org/onlinepubs/7908799/xns/getsockopt.html
我自己被困在这个问题上，文档非常神秘。这里有更详细的文档：http: //pubs.opengroup.org/onlinepubs/7908799/xns/getsockopt.html
