藍色情懷

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/*
 * Compile:
 *
 * 	$ gcc -o get_wan_ipaddr get_wan_ipaddr.c -Wall
 *
 * WAN IP Detection methods:
 *	$ dig +short -p 8253 @ipcast1.dynupdate.no-ip.com wan.ip
 *	$ curl http://ip1.dynupdate.no-ip.com
 *	$ external_ip=`lynx -dump "http://checkip.dyndns.org" | awk -F":" '{print $2}'` && echo $external_ip
 *	$ external_ip=`html2text http://checkip.dyndns.org | awk -F"Current IP Address:" '{print $2}'` && echo $external_ip
 *
 *
 * References:
 *
 *	http://www.readynas.com/forum/viewtopic.php?t=61297&p=343930
 * 	http://souptonuts.sourceforge.net/code/http_get.c.html
 * 	http://tools.ietf.org/html/rfc2202
 *	http://wiki.mikrotik.com/wiki/Dynamic_DNS_Update_Script_for_No-IP_DNS
 *	https://github.com/AntonioCS/no-ip.com-bash-updater
 *	http://www.os-cms.net/blog/view/21/NO-IP-client-written-in-PHP
 *	http://wiki.dreamhost.com/Dynamic_DNS
 *	http://patinya-tuk.blogspot.tw/2009/09/ddnshowtoopenwrt.html
 *	http://man7.org/linux/man-pages/man3/inet_pton.3.html
 *	http://beej.us/guide/bgnet/output/html/multipage/inet_ntopman.html
 *
 */

#include <arpa/inet.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <netinet/in.h>
#include <signal.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netdb.h>
#include <unistd.h>

#define USER_AGENT		"Linux Update Client/0.01 VERSION/1.00 jackie.cpluspluc@gmail.com"
#define WANIP_QUERY_SERVER	"ip1.dynupdate.no-ip.com"
#define WANIP_QUERY_SVR		"myip.dnsomatic.com"
#define SA			struct sockaddr
#define MAXLINE			16384
#define MAXSUB			16384
#define LISTENQ			1024
#define HTTP_PORT		80
#define IP_LENGTH		128
//#define __DEBUG__
#ifdef __DEBUG__
#define LOG_MSG			printf
#else
#define LOG_MSG(...)
#endif

extern int h_errno;

int tcp_connect(int *sock, const char* host, const char *port)
{
	int i;
	char str[50];
	char **pptr, *inet;
	struct hostent *hptr;
	struct sockaddr_in servaddr;

	if ((hptr = gethostbyname(host)) == NULL) {
		fprintf(stderr, " Server down error for host: %s: %s",
				host, hstrerror(h_errno));
		return -1;
	}
	LOG_MSG("hostname: %s \n", hptr->h_name);
	if (hptr->h_addrtype == AF_INET
		&& (pptr = hptr->h_addr_list) != NULL) {
		inet = inet_ntop(hptr->h_addrtype, *pptr, str, sizeof(str));
		LOG_MSG("address: %s\n", inet);
	} else {
		fprintf(stderr, "Error call inet_ntop \n");
	}

	*sock = socket(AF_INET, SOCK_STREAM, 0);
	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(HTTP_PORT);
	inet_pton(AF_INET, str, &servaddr.sin_addr);

	i = connect(*sock, (SA *) & servaddr, sizeof(servaddr));
	if (i < 0)  {
		close(*sock);
		return i;
	}
	else
		return 0;
	return -1;
}

int file_read(int fh, char *recvline, int len) {
	int n;
	if (!fh)
		return -1;
	while ((n = read(fh, recvline, MAXLINE)) > 0) {
		recvline[n] = '\0';
		//LOG_MSG("%s", recvline);  // <-- this
	}
	return n;
}

int file_write(int fh, const char* sendline, int len) {
	if (!fh)
		return -1;
	if (write(fh, sendline, len) != len) {
		return -1;
	}
	return 0;
}

int http_session(int sock, const char *buf)
{
#ifdef __DEBUG__
	char	*p, *q;
	p = buf;
	while ((q = strchr(p, '\n'))) {
		*q = 0;
		fprintf(stderr, "> %s\n", p);
		*q++ = '\n';
		p = q;
	}
	if (*p)
		fprintf(stderr, "> %s\n", p);
#endif
	if (file_write(sock, buf, strlen(buf)) < 0) {
		close(sock);
		return -1;
	}
	if (file_read(sock, buf, MAXLINE) < 0) {
		close(sock);
		return -1;
	}

#ifdef __DEBUG__
	LOG_MSG("\n\n");
	p = buf;
	while ((q = strchr(p, '\n'))) {
		*q = 0;
		fprintf(stderr, "< %s\n", p);
		*q++ = '\n';
		p = q;
	}
	if (*p)
		fprintf(stderr, "< %s\n", p);
#endif
	return 0;
}

bool isValidIPAddress(char *ipAddress)
{
	struct sockaddr_in sa;
	int result = inet_pton(AF_INET, ipAddress, &(sa.sin_addr));
	return result != 0;
}

int detecte_wan_ipaddr(char *wan_ip)
{
	int socket_fd = 0;
	char buffer[MAXLINE];
	char *p = NULL;

	memset(buffer, 0, sizeof(buffer));

	snprintf(buffer, MAXSUB,
			"GET / HTTP/1.1\r\n"
			"Host: %s\r\n"
			"User-Agent: %s\r\n\r\n"
			, WANIP_QUERY_SVR, USER_AGENT);

	if (tcp_connect(&socket_fd, WANIP_QUERY_SVR, HTTP_PORT) < 0)
		return -1;

	if (http_session(socket_fd, buffer) < 0)
		return -1;
	close(socket_fd);
	if ((p = strrchr(buffer, '\n'))){
		strcpy(wan_ip, ++p);
		if (isValidIPAddress(wan_ip) == false)
			return -1;
	}
	return 0;
}

int main(int argc, char **argv)
{
	char wan_ip[IP_LENGTH];
	memset(wan_ip, 0, sizeof(wan_ip));
	if (detecte_wan_ipaddr(wan_ip) == 0)
		printf("%s\n", wan_ip);
	else
		return -1;
	return 0;
}