[置顶] linux 判断是否是合法ip，根据域名获取ip

//
// Created by darren on 18-1-31.
//

#include <stdio.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>

bool isValidIP(const char *ipstr);

int get_ip_by_domain(const char *domain, char *ip);

void test_Big_endian();

int is_valid_ip(const char *ip_str);

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

printf("isValidIP():%d\n", isValidIP(argv[1]));
printf("is_valid_ip:%d\n", is_valid_ip(argv[1]));

char tmp[256];
int ret = get_ip_by_domain(argv[1], tmp);
printf("domain:%d,%s\n", ret, tmp);

test_Big_endian();

return 0;
}

int is_valid_ip(const char *ip_str) {
struct sockaddr_in sa;
int result = inet_pton(AF_INET, ip_str, &(sa.sin_addr));
if (result == 0) {
return result;
}
return 1;
}

void test_Big_endian() {
unsigned long a = 0x12345678;
unsigned char *p = (unsigned char *) (&a);
printf("主机字节序:%0x    %0x   %0x   %0x\n", p[0], p[1], p[2], p[3]);
unsigned long b = htonl(a);  //将主机字节序转化成了网络字节序
p = (unsigned char *) (&b);
printf("网络字节序:%0x    %0x   %0x   %0x\n", p[0], p[1], p[2], p[3]);

}

//根据域名获取ip
int get_ip_by_domain(const char *domain, char *ip) {
char **pptr;
struct hostent *hptr;
hptr = gethostbyname(domain);
if (NULL == hptr) {
printf("gethostbyname error for host:%s/n", domain);
return -1;
}
for (pptr = hptr->h_addr_list; *pptr != NULL; pptr++) {
if (NULL != inet_ntop(hptr->h_addrtype, *pptr, ip, INET_ADDRSTRLEN)) {
return 0; // 只获取第一个 ip
}
}
return -1;
}

// ip 合法性
bool isValidIP(const char *ipstr) {
if (!ipstr) return false;
int a, b, c, d;
int tmp = sscanf(ipstr, "%d.%d.%d.%d", &a, &b, &c, &d);
printf("tmp:%d\n", tmp);
if (4 != tmp) return false;
printf("inet_addr:%d,%d,%d,%d,%d\n", inet_addr(ipstr), a, b, c, d);
if (!(0 > a || 255 < a ||
0 > b || 255 < b ||
0 > c || 255 < c ||
0 > d || 255 < d) && INADDR_NONE != inet_addr(ipstr)) {
return true;
}
return false;
}