Linux網絡編程：獲取本機的公網IP

Linux網絡編程：獲取本機的公網IP

1. #include <stdio.h>
2. #include <string.h>
3. #include <sys/types.h>
4. #include <errno.h>
5. #include <sys/stat.h>
6. #include <fcntl.h>
7. #include <unistd.h>
8. #include <stdlib.h>
9. #include <netdb.h>
10. #include <stddef.h>
11. #include <netinet/in.h>
12. #include <arpa/inet.h>
13. #include <sys/socket.h>
15. #define BUF_SIZE 512
17. int port = 80;
19. void getip(char *url)
20. {
21. struct sockaddr_in pin;
22. struct hostent *nlp_host;
23. int sd = 0;
24. int len = 0;
25. int i, count = 0;
26. int recv_start = 0, recv_end = 0;
27. char buf[BUF_SIZE] = { 0 }, myurl[100] =
28. {
29. 0};
30. char host[100] = { 0 }, GET[100] =
31. {
32. 0}, header[240] =
33. {
34. 0};
35. char *pHost = 0;
37. ///get the host name and the relative address from url name!!!
38. strcpy(myurl, url);
39. for (pHost = myurl; *pHost != '/' && *pHost != '\0'; ++pHost) ;
40. if ((int)(pHost - myurl) == strlen(myurl))
41. strcpy(GET, "/");
42. else
43. strcpy(GET, pHost);
44. *pHost = '\0';
45. strcpy(host, myurl);
47. ///setting socket param
48. if ((nlp_host = gethostbyname(host)) == 0)
49. {
50. perror("error get host\n");
51. exit(1);
52. }
54. bzero(&pin, sizeof(pin));
55. pin.sin_family = AF_INET;
56. pin.sin_addr.s_addr = htonl(INADDR_ANY);
57. pin.sin_addr.s_addr = ((struct in_addr *)(nlp_host->h_addr))->s_addr;
58. pin.sin_port = htons(port);
60. if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
61. {
62. perror("Error opening socket!!!\n");
63. exit(1);
64. }
66. ///together the request info that will be sent to web server
67. ///Note: the blank and enter key byte is necessary,please remember!!!
68. strcat(header, "GET");
69. strcat(header, " ");
70. strcat(header, GET);
71. strcat(header, " ");
72. strcat(header, "HTTP/1.1\r\n");
73. strcat(header, "HOST:");
74. strcat(header, host);
75. strcat(header, "\r\n");
76. strcat(header, "ACCEPT:*/*");
77. strcat(header, "\r\nConnection: close\r\n\r\n\r\n");
79. ///connect to the webserver,send the header,and receive the web sourcecode
80. if (connect(sd, (void *)&pin, sizeof(pin)) == -1)
81. printf("error connect to socket\n");
83. if (send(sd, header, strlen(header), 0) == -1)
84. {
85. perror("error in send \n");
86. exit(1);
87. }
89. ///send the message and wait the response!!!
90. len = recv(sd, buf, BUF_SIZE, 0);
91. if (len < 0)
92. printf("receive data error!!!\n");
93. else
94. {
95. printf("%s", &(buf[157]));
96. }
97. close(sd);
99. }
101. int main()
102. {
103. char *url = "www.3322.org/dyndns/getip";
104. getip(url);
105. return 0;
106. }

運行結果：

1. [[email protected] test]#
2. [[email protected] test]# gcc getIP.c -o getIP
3. [[email protected] test]# ./getIP
4. 218.13.34.138
5. [[email protected] test]#