Linux setsockopt 的奇怪错误，“协议不可用”
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时间：2020-08-06 05:36:29 来源:igfitidea点击:
Weird error with setsockopt, "Protocol not available"
提问by W00t
The applicable code is below, as is the exact error.
适用的代码如下，确切的错误也是如此。
sd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
if ( setsockopt( sd, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on) ) < 0 )
{
printf("%s\n", strerror(errno));
}
if ( setsockopt( sd, IPPROTO_IP, IP_DF, &on, sizeof(on) ) < 0 )
{
printf("%s\n", strerror(errno));
printf("DF\n");
}
Error:
错误：
root@PC:~# gcc main.c
main.c: In function ‘main':
main.c:71: warning: format not a string literal and no format arguments
root@PC:~# ./a.out localhost
Protocol not available
DF
It's odd that the second setsockopt is erroring, while the first one isn't.
奇怪的是，第二个 setsockopt 出错了，而第一个没有。
采纳答案by Ignacio Vazquez-Abrams
IP_DFis a packet flag, not a socket option. Valid socket options are given in the ip(7)man page.
IP_DF是数据包标志，而不是套接字选项。ip(7)手册页中给出了有效的套接字选项。
回答by sardok
from ip(7) man page;
来自 ip(7) 手册页；
IP_NODEFRAG (since Linux 2.6.36)
If enabled (argument is nonzero), the reassembly of outgoing packets is
disabled in the netfilter layer. This option is only valid for
SOCK_RAW sockets. The argument is an integer.
