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域名，ip相互轉換（Linux，getaddrinfo, getnameinfo）--- 轉

參考鏈接：

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

代碼：

`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 }

結果：

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

posted on 2012-11-12 14:44 大龍閱讀(4197) 評論(0) 編輯收藏引用

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