域名，ip相互转换（Linux，getaddrinfo, getnameinfo）--- 转

域名，ip相互转换（Linux，getaddrinfo, getnameinfo）--- 转

参考链接：

http://en.wikipedia.org/wiki/Getaddrinfo

代码：

 

01	/* ip_to_hostname ip */

02	#include <sys/types.h>

03	#include <sys/socket.h>

04	#include <netdb.h>

05	#include <unistd.h>

06	#include <stdio.h>

07	#include <stdlib.h>

08	#include <string.h>

09

10	int main(int argc, char *argv[])

11

{

12	if (argc != 2)

13

{

14	fprintf(stderr, "Usage: %s hostname\n", argv[0]);

15	exit(EXIT_FAILURE);

16

}

17	struct addrinfo hints;

18	struct addrinfo *result, *result_pointer;

19

int ret;

20	/* obtaining address matching host */

21	memset(&hints, 0, sizeof(struct addrinfo));

22	hints.ai_family = AF_UNSPEC;

23	hints.ai_socktype = SOCK_STREAM;

24	hints.ai_flags = AI_CANONNAME | AI_NUMERICHOST;

25	hints.ai_protocol = 0;  /* any protocol */

26

27	//      ret = getaddrinfo(argv[1], NULL, &hints, &result);

28	ret = getaddrinfo(argv[1], NULL, &hints, &result);

29	if (ret != 0)

30

{

31	fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ret));

32	exit(EXIT_FAILURE);

33

}

34	/* traverse the returned list and output the ip addresses */

35	for (result_pointer = result; result_pointer != NULL; result_pointer = result_pointer->ai_next)

36

{

37	char hostname[1025] = "";

38	ret = getnameinfo(result_pointer->ai_addr, result_pointer->ai_addrlen, hostname, sizeof(hostname), NULL, 0, NI_NAMEREQD);

39	if (ret != 0)

40

{

41	fprintf(stderr, "error in getnameinfo: %s \n", gai_strerror(ret));

42

}

43

else

44

{

45	printf("hostname: %s \n", hostname);

46

}

47	//              printf("hostname: %s \n", result_pointer->ai_canonname);

48

}

49	freeaddrinfo(result);

50	exit(EXIT_SUCCESS);

51

}

 

 

01	/* hostname_to_ip hostname */

02	#include <sys/types.h>

03	#include <sys/socket.h>

04	#include <netdb.h>

05	#include <unistd.h>

06	#include <stdio.h>

07	#include <stdlib.h>

08	#include <string.h>

09

10	int main(int argc, char *argv[])

11

{

12	if (argc != 2)

13

{

14	fprintf(stderr, "Usage: %s hostname\n", argv[0]);

15	exit(EXIT_FAILURE);

16

}

17	struct addrinfo hints;

18	struct addrinfo *result, *result_pointer;

19

int ret;

20	/* obtaining address matching host */

21	memset(&hints, 0, sizeof(struct addrinfo));

22	hints.ai_family = AF_UNSPEC;

23	hints.ai_socktype = SOCK_STREAM;

24	hints.ai_flags = AI_CANONNAME;

25	hints.ai_protocol = 0;  /* any protocol */

26

27	//      ret = getaddrinfo(argv[1], NULL, &hints, &result);

28	ret = getaddrinfo(argv[1], NULL, &hints, &result);

29	if (ret != 0)

30

{

31	fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(ret));

32	exit(EXIT_FAILURE);

33

}

34	/* traverse the returned list and output the ip addresses */

35	for (result_pointer = result; result_pointer != NULL; result_pointer = result_pointer->ai_next)

36

{

37	char hostname[1025] = "";

38	ret = getnameinfo(result_pointer->ai_addr, result_pointer->ai_addrlen, hostname, sizeof(hostname), NULL, 0, NI_NUMERICHOST);

39	if (ret != 0)

40

{

41	fprintf(stderr, "error in getnameinfo: %s \n", gai_strerror(ret));

42

continue;

43

}

44

else

45

{

46	printf("IP: %s \n", hostname);

47

}

48

}

49	freeaddrinfo(result);

50	exit(EXIT_SUCCESS);

51

}

 

结果：

root@localhost :/home/James/mypro/Linux-Pro/Network# ./hostname_to_ip baidu.com
IP: 123.125.114.144
IP: 220.181.111.85
IP: 220.181.111.86
root@localhost :/home/James/mypro/Linux-Pro/Network# ./ip_to_hostname 220.181.111.86
error in getnameinfo: Name or service not known
root@localhost :/home/James/mypro/Linux-Pro/Network# ./ip_to_hostname 10.0.0.78
hostname: localhost

root@localhost:/home/James/mypro/Linux-Pro/Network# ./ip_to_hostname 59.66.137.62
hostname: th137062.ip.tsinghua.edu.cn
root@localhost:/home/James/mypro/Linux-Pro/Network# ./ip_to_hostname 202.106.182.229
hostname: mail182-229.sinamail.sina.com.cn
root@localhost:/home/James/mypro/Linux-Pro/Network# ./ip_to_hostname 211.147.4.7
hostname: mail3.douban.com