#include <netdb.h>
struct hostent* gethostent(void);
作用:返回本機主機信息。該函數讀取/etc/hosts,逐行返回此文件中內容,即多次調用每次返回不同值,不可重入,示例:
struct hostent* p;
p = gethostent();
while (p) {
printf("%s\n", p->h_name);
p = gethostent();
}
struct protoent* getprotoent(void)
作用:返回協議信息。該函數讀取/etc/protocols,逐行返回此文件中內容,示例:
struct protoent* p;
p = getprotoent();
while (p) {
printf("%s\n", p->p_name);
p = getprotoent();
}
struct servent* getservent(void)
作用:返回服務名。該函數讀取/etc/services,逐行返回文件內容,示例:
struct servent* p;
p = getservent();
while (p) {
printf("%s\n", p->s_name);
p = getservent();
}
#include <sys/typs.h>
#include <sys/socket.h>
#include <netdb.h>
int getaddrinfo(
const char* node,
const char* service,
const struct adddrinfo* hints,
struct adddrinfo** res);
作用:整合上述單個函數的功能,提供一個一次獲取所有信息的接口,同時此函數是線程安全的,示例:
struct addrinfo* p;
struct addrinfo hint;
hint.ai_flags = AI_CANONNAME;
getaddrinfo("localhost", "telnet", &hint, &p);
for (struct addrinfo* ploop = p; ploop; ploop = ploop->ai_next) {
printf("%s\n", ploop->ai_canonname);
}