OK
3) socket(AF_INET, SOCK_STREAM, 0);
protocol = 0
if (protocol == answer->protocol) : FALSE
check else :
/* Check for the two wild cases. */
if (IPPROTO_IP == protocol) {
protocol = answer->protocol;
break;
}
: TRUE
note that protocol value 0 is substituted with the real value of IPPROTO_TCP in line:
OK
/* 上面例子（3）解释了文章最开始提出的疑问，现在protocol 已经被替换成了6 */
4) socket(AF_INET, SOCK_DGRAM, 0);
protocol = 0
*answer = inetsw_array
if (protocol == answer->protocol) : FALSE
check else :
/* Check for the two wild cases. */
if (IPPROTO_IP == protocol) {
protocol = answer->protocol;
break;
}
: TRUE
note that protocol value 0 is substituted with the real value of IPPROTO_UDP in line:
OK
5) socket(AF_INET, SOCK_RAW, 0);
protocol = 0
protocol == answer->protocol && protocol == IPPROTO_IP so : if (protocol != IPPROTO_IP) is FALSE
not OK -> EPROTONOSUPPORT
6) socket(AF_INET, SOCK_STREAM, 9); (where 9 can be any protocol except IPPROTO_TCP)
protocol = 9
check else :
break;
}
if (IPPROTO_IP == answer->protocol)
break;
both are a FALSE
7) socket(AF_INET, SOCK_DGRAM, 9); (where 9 can be any protocol except IPPROTO_UDP)
same as above
8) socket(AF_INET, SOCK_RAW, 9); (where 9 can be *any* protocol except 0)
protocol = 9