linux 判斷是否是合法ip，根據域名獲取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("主機字節序:%0x    %0x   %0x   %0x\n", p[0], p[1], p[2], p[3]);
    unsigned long b = htonl(a);  //將主機字節序轉化成了網絡字節序
    p = (unsigned char *) (&b);
    printf("網絡字節序:%0x    %0x   %0x   %0x\n", p[0], p[1], p[2], p[3]);

}

//根據域名獲取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; // 只獲取第一個 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;
}