• 根据域名找到IP地址 getipbyhostname.c

    * getipbyhostname.c

    1. #include   /* gethostbyname */
    2. #include    /* time_t, localtime */
    3. #include   /* errno */
    4. #include  /* struct in_addr */
    5. #include   /* inet_ntoa */
    6. #include  /* strncpy */
    7. #include  /* va_start, va_end */
    8. #include 
    9.  
    10. #define E_FAIL -1
    11. #define E_OK 0
    12.  
    13. #define _FL_ __FILE__,__LINE__
    14.  
    15. #define E_MESSAGE 10000
    16. #define E_ALLOC  10300
    17. #define E_SOCKFD_SEND  10359
    18. #define E_SOCKFD_RECV  10360
    19. #define E_OSCALL    10201  /* 系统函数(%s)调用出错 */
    20. #define E_FUNCALL   10202  /* 平台函数(%s)调用出错 */
    21.  
    22. #ifndef pid_t
    23. typedef int pid_t;
    24. #endif
    25. extern  pid_t getpid(void);
    26.  
    27. int bclerrlog(int appcode, char *file, long line, const char *fmt, ...)
    28. {
    29.   time_t now_time;
    30.   struct tm *info;
    31.   char dt_buf[64];
    32.   char appmsg[512];
    33.   va_list ap;
    34.  
    35.   va_start(ap, fmt);
    36.   /* bclerreg(appcode, file, line, fmt, ap); */
    37.   vsnprintf(appmsg, 512, fmt, ap);
    38.  
    39.   time( &now_time );
    40.   info = localtime( &now_time );
    41.   strftime(dt_buf, 80, "%Y-%m-%d %H:%M:%S", info);
    42.   fprintf(stderr, "---- %s ----\n", dt_buf);
    43.  
    44.   fprintf(stderr, "PID: %d\tFile: %s\tLine: %ld\n", getpid(), file, line);
    45.   fprintf(stderr, "App Error: %d - %s\n", appcode, appmsg);
    46.   fprintf(stderr, "System Error: %d - %s\n", errno, strerror(errno));
    47.   va_end(ap);
    48. }
    49.  
    50. #if 0
    51. typedef union {
    52.   unsigned char a[4];
    53.   unsigned int m;
    54. } IPAddr_t;
    55. #endif
    56.  
    57. int main(int argc, char *argv[])
    58. {
    59.   char host_name[256];
    60.   struct hostent *host_entry;
    61.   char *IPbuffer;
    62.   struct in_addr addr;
    63.  
    64.   /* strncpy(host_name, "p3-sign.douyinpic.com", 256); */
    65.   if (argc < 2) {
    66.     fprintf(stdout, "Usage: %s xx.xx.com", argv[0]);
    67.     return E_OK;
    68.   }
    69.   strncpy(host_name, argv[1], 256);
    70.   printf("Hostname: [%s]\n", host_name);
    71.  
    72.   /* To retrieve host information */
    73.   host_entry = gethostbyname(host_name);
    74.   if (host_entry == NULL) {
    75.     bclerrlog(E_OSCALL, _FL_, "gethostbyname()");
    76.     return E_FAIL;
    77.   }
    78.   /* To convert an Internet network address into ASCII string */
    79.   for (int i = 0; i < host_entry->h_length; i++) {
    80.     IPbuffer = inet_ntoa(*((struct in_addr*)host_entry->h_addr_list[i]));
    81.     memcpy(&addr, host_entry->h_addr_list[i], sizeof(struct in_addr));
    82.     printf("Host IP#%d: %s\t%08x\n", i, IPbuffer, addr.s_addr);
    83.   }
    84.  
    85.   return E_OK;
    86. }

    $ cc -g getipbyhostname.c -o getipbyhostname

    $ ./getipbyhostname p3-sign.douyinpic.com
    Hostname: [p3-sign.douyinpic.com]
    Host IP#0: 221.231.92.240       f05ce7dd
    Host IP#1: 180.101.197.251      fbc565b4
    Host IP#2: 116.207.144.248      f890cf74
    Host IP#3: 58.215.47.228        e42fd73a

    windows版:

    需要引入头文件

    1. #include  /* WSADATA */
    2. #include  /* getaddrinfo */
    3. /* link with Ws2_32.lib */
    4. #pragma comment (lib, "Ws2_32.lib")

    typedef int (*IpHandler_t)(const char* ip);

    int getipv4byhostname(const char* hostname, IpHandler_t ipHandler);

    1. int getipv4byhostname(const char* hostname, IpHandler_t ipHandler) {
    2. 	//-----------------------------------------
    3. 	// Declare and initialize variables
    4. 	WSADATA wsaData;
    5. 	int iResult;
    6.  
    7. 	struct addrinfo* result = NULL;
    8. 	struct addrinfo* ptr = NULL;
    9. 	struct addrinfo hints;
    10.  
    11. 	// Initialize Winsock
    12. 	iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    13. 	if (iResult != 0) {
    14. 		printf("WSAStartup failed: %d\n", iResult);
    15. 		return 1;
    16. 	}
    17. //--------------------------------
    18. // Setup the hints address info structure
    19. // which is passed to the getaddrinfo() function
    20. 	ZeroMemory(&hints, sizeof(hints));
    21. 	hints.ai_family = AF_UNSPEC;
    22. 	hints.ai_socktype = SOCK_STREAM;
    23. 	hints.ai_protocol = IPPROTO_TCP;
    24.  
    25. 	int dwRetval = getaddrinfo(hostname, "0", &hints, &result);
    26. 	if (dwRetval != 0) {
    27. 		printf("getaddrinfo failed with error: %d\n", dwRetval);
    28. 		WSACleanup();
    29. 		return 1;
    30. 	}
    31.  
    32. 	struct in_addr sockaddr_ipv4;
    33. 	char ipv4[INET_ADDRSTRLEN];
    34. 	const char* ip;
    35. 	// Retrieve each address and print out the hex bytes
    36. 	for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {
    37. 		sockaddr_ipv4 = ((struct sockaddr_in*)ptr->ai_addr)->sin_addr;
    38. 		ip = inet_ntop(AF_INET, &sockaddr_ipv4, ipv4, sizeof(ipv4));
    39. 		ipHandler(ip);
    40. 	}
    41. 	return 0;
    42. }

      处理函数：

    1. int ipHandler(const char *ip) {
    2.     printf("IP=[%s]\n", ip);
    3.     return 0;
    4. }

    调用:

    1.     char hostname[64];
    2.     strncpy(hostname, "tcbox.baidu.com", 64);
    3.     printf("host=[%s]\n", hostname);
    4.  
    5.     getipv4byhostname(hostname, ipHandler);

    121.228.183.55

    查询DNS 参照RFC1035

    main.c

    1. #include "bcl_udp.h"
    2.     
    3. int main() {
    4.     char hostname[32] = {'\0'};
    5.     struct ipv4head ipv4List;
    6.     struct ipv4_entry *n1;
    7.  
    8.     strcpy(hostname, "qq.com");  /* octipus.net, www.google.co.il */
    9.     bcl_dns_query(&ipv4List, hostname, "192.168.64.1");  /* Query gateway(DNS) */
    10.     while(!TAILQ_EMPTY(&ipv4List)) {
    11.         n1 = TAILQ_FIRST(&ipv4List);
    12.         TAILQ_REMOVE(&ipv4List, n1, entries);
    13.         printf("n1->data=%s\n", n1->data);
    14.         free(n1);
    15.     }
    16.     return 0;
    17. }

    * bcl_udp.h

    1. #ifndef ERRLOG_BCL_UDP_H
    2. #define ERRLOG_BCL_UDP_H
    3.  
    4. #include 
    5.  
    6.  
    7. struct ipv4_entry {
    8.     char data[16];
    9.     TAILQ_ENTRY(ipv4_entry) entries;
    10. };
    11. TAILQ_HEAD(ipv4head, ipv4_entry);
    12.  
    13. int bcl_dns_query(struct ipv4head *head, char *host_name, const char *dns_ip);
    14.  
    15. #endif //ERRLOG_BCL_UDP_H

    * bcl_udp.c

    dns-packet-structure

    1. #ifdef __cplusplus
    2. extern "C" {
    3. #endif
    4.  
    5. #include  /* bzero */
    6. #include  /* inet_addr */
    7. #include  /* close */
    8. #include  /* strcat, memset */
    9. #include  /* getenv(), rand() */
    10.  
    11. #include "bcl_udp.h"
    12. #include "arclog.h"
    13. #include "bcl_socket.h"
    14.  
    15. #define PRIVATE static
    16.  
    17. typedef union {
    18.     unsigned char c[4];
    19.     in_addr_t addr;  /* unsigned int */
    20. } IPv4_t;
    21.  
    22. in_addr_t ip2int(const char *ip) {
    23.     IPv4_t un;
    24.     int i, j;
    25.     un.c[0] = un.c[1] = un.c[2] = un.c[3] = 0;
    26.     for (i = 0, j = 0; i < 16 && ip[i] != '\0'; i++) {
    27.         if (0x30 <= ip[i] && ip[i] < 0x3a) { /* '0','9' */
    28.             un.c[j] *= 10;
    29.             un.c[j] += ip[i] - 0x30;
    30.         } else if (ip[i] == 0x2e) { /* '.' */
    31.             j += 1;
    32.         }
    33.     }
    34.     return un.addr;
    35. }
    36.  
    37. int bcl_udp_datetime(char buf[]) {
    38.     int sockfd;
    39.     ssize_t n;
    40.     /* sockfd = socket(PF_INET, SOCK_DGRAM, 0); */
    41.     sockfd = bcl_tcp_connector(ip2int("129.6.15.32"), 13);
    42.     if (sockfd < 0) {
    43.         bclerrend();
    44.         return E_FAIL;
    45.     }
    46.     /* n = sendto(sockfd, buf, 2, 0, (struct sockaddr *)&serv, sizeof(serv)); */
    47.     bcl_send_nbytes(sockfd, buf, 2);
    48.     /* n = recvfrom(sockfd, buf, 150, 0, (struct sockaddr *)0, (socklen_t *)0); */
    49.     bzero(buf, 150);
    50.     n = bcl_recv_nbytes(sockfd, buf, 150, 5);
    51.     if (n < 2) {
    52.         bclerrlog(E_OSCALL, _FL_, "recv from error");
    53.         return E_FAIL;
    54.     }
    55.     buf[n - 2] = 0;
    56.     /* bcl_debug("datetime from 129.6.15.32: %s", buf); */
    57.     close(sockfd);
    58.     return E_OK;
    59. }
    60.  
    61. typedef struct {
    62.     u_short transId; /* 0xb6f6 */
    63.     u_short flags;  /* 0x0100 Standard query */
    64.     u_short questions; /* 0x0001 */
    65.     u_char rss[6];  /* 00 00 00 00 00 00 */
    66. } DnsHdr_t;
    67.  
    68. #define HOST_LEN 64
    69.  
    70. typedef struct {
    71.     u_char name[2]; /* ptr */
    72.     u_short type; /* 0x0005 alias */
    73.     u_short in; /* 0x0001 */
    74.     u_int32_t ttl; /* 81, 1min21s */
    75.     u_short dataLen;  /* 0x0017, 23 */
    76.     char cname[HOST_LEN];  /* 3www31633com8163jiasu3com */
    77. } __attribute__((packed)) DnsAnswer_t;
    78.  
    79. /**
    80.  * @ref: https://www.linuxquestions.org/questions/linux-networking-3/dns-packet-structure-289886/
    81.  * @param name "p3-sign.douyinpic.com"
    82.  * @param entry  "7p3-sign9douyinpic3com"
    83.  * @return
    84.  */
    85. PRIVATE char *dns_entry(char *entry, const char *name) {
    86.     const char *p = name;
    87.     char *q = entry;
    88.     int8_t len;
    89.  
    90.     while ('\0' != *p) {
    91.         len = 0;
    92.         for (; *p && *p != '.'; p++) {
    93.             len += 1;
    94.         }
    95.         *q++ = len;
    96.         memcpy(q, p - len, len);
    97.         q += len;
    98.         p++;
    99.     }
    100.     return q;
    101. }
    102.  
    103. #define SWAP(a, b, type) do { type _t = a; a = b; b = _t;} while(0);
    104.  
    105. #define REVERSE(a, b, type)  do { \
    106.    type *p = a, *q = b;           \
    107.    type t;                        \
    108.    if (p > q) { SWAP(p, q, type *);}  \
    109.    for (; p < q; p++, q--) { \
    110.        t = *p; \
    111.        *p = *q; \
    112.        *q = t; \
    113.    } \
    114. } while (0);
    115.  
    116. void IPv4_toString(char *s, IPv4_t ipv4) {
    117.     int i;
    118.     char *t;
    119. #ifdef __ORDER_LITTLE_ENDIAN__
    120.     for (i = 0; i < 4; i++) {
    121. #else
    122.     for (i = 3; 0 <= i; i--) {
    123. #endif
    124.         t = s;
    125.         while (ipv4.c[i]) {
    126.             *s++ = ipv4.c[i] % 10 + 0x30;
    127.             ipv4.c[i] /= 10;
    128.         }
    129.         REVERSE(s-1, t, char);
    130.         *s++ = '.';
    131.     }
    132.     *(s-1) = '\0';
    133. }
    134.  
    135. int bcl_dns_query(struct ipv4head *head, char *host_name, const char *dns_ip) {
    136.     int sockfd;
    137.     char buf[1024] = {'\0'};
    138.     struct sockaddr_in dest_addr;
    139.     DnsHdr_t header;
    140.     char *p = NULL;
    141.     off_t queryLen;
    142.     DnsAnswer_t ans;
    143.     IPv4_t ipv4;
    144.     struct ipv4_entry *n1 = NULL;
    145.  
    146.     sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    147.     if (sockfd < 0) {
    148.         bclerreg(E_OSCALL, _FL_, "socket() UDP");
    149.         return E_FAIL;
    150.     }
    151.     /* DNS address */
    152.     memset(&dest_addr, 0, sizeof(struct sockaddr_in));
    153.     dest_addr.sin_family = AF_INET;
    154.     dest_addr.sin_addr.s_addr = ip2int(dns_ip);
    155.     dest_addr.sin_port = htons(53);  /* DNS port 53 */
    156.     if (connect(sockfd, (const struct sockaddr *) &dest_addr, sizeof(dest_addr)) < 0) {
    157.         bclerreg(E_OSCALL, _FL_, "connect()");
    158.         return E_FAIL;
    159.     }
    160.     /* DNS query packet */
    161.     header.transId = (u_short) rand();
    162.     header.flags = htons(0x0100);
    163.     header.questions = htons(0x0001);
    164.     memset(header.rss, 0, sizeof(header.rss));
    165.  
    166.     memcpy(buf, &header, sizeof(header));
    167.     p = buf + sizeof(header);
    168.     /* queries: p3-sign.douyinpic.com  */
    169.     p = dns_entry(p, host_name);
    170.     *p++ = '\0';
    171.     /* type A, class IN */
    172.     *p++ = 0x00; *p++ = 0x01;
    173.     *p++ = 0x00; *p++ = 0x01;
    174.  
    175.     queryLen = p - buf;
    176.     if (send(sockfd, buf, queryLen, 0) < 0) {
    177.         bclerreg(E_OSCALL, _FL_, "send()");
    178.         return E_FAIL;
    179.     }
    180.     memset(buf, 0, 1024);
    181.     if (recv(sockfd, buf, 1024, 0) < 1) {
    182.         bclerreg(E_OSCALL, _FL_, "recv()");
    183.         return E_FAIL;
    184.     }
    185.     p = buf + queryLen;
    186.     /* Answers: buf + queryLen */
    187.     TAILQ_INIT(head);
    188.     while (*p != 0x00) {
    189.         /* bcl_xxd(p, 0xa0); */
    190.         if (*(u_char *)p == 0xc0) {
    191.             /* c0 0c, c0 14 */
    192.             ans.dataLen = ntohs(((DnsAnswer_t *)p)->dataLen);
    193.         }
    194.         printf("dataLen=%d\n", ans.dataLen);
    195.         bcl_xxd(((DnsAnswer_t *)p)->cname, ans.dataLen);
    196.         if (4 == ans.dataLen) { /* IPv4 */
    197.             memcpy(&ipv4, &((DnsAnswer_t *)p)->cname, 4);
    198.             n1 = (struct ipv4_entry *)malloc(sizeof(struct ipv4_entry));
    199.             IPv4_toString(n1->data, ipv4);
    200.             TAILQ_INSERT_TAIL(head, n1, entries);
    201.         }
    202.         p += sizeof(DnsAnswer_t) - HOST_LEN + ans.dataLen;
    203.     }
    204.     return E_OK;
    205. }
    206.  
    207. #ifdef __cplusplus
    208. };
    209. #endif

    调试用 bcl_xxd实现， 错误日志

    1. #ifndef byte
    2. typedef unsigned char byte;
    3. #endif
    4. #ifndef uint8_t
    5. typedef unsigned char uint8_t;
    6. #endif
    7. #ifndef uint16_t
    8. typedef unsigned short uint16_t;
    9. #endif
    10.  
    11. uint8_t arc_xxd(byte *s, uint8_t len, void *param);
    12.  
    13. void bcl_xxd(const void *s, size_t len)
    14. {
    15.     uint16_t line = 0;
    16.     byte *t = (byte *)s;
    17.     uint8_t b;
    18.     size_t left = len;
    19.  
    20.     for (; ;) {
    21.         if (left > 16) {
    22.             b = arc_xxd(t, 16, &line);
    23.         } else {
    24.             b = arc_xxd(t, left, &line);
    25.         }
    26.         if (b < 1) {break;}
    27.         left -= b;
    28.         if (left <= 0) {break;}
    29.         t += b;
    30.     }
    31. }
    32.  
    33. uint8_t arc_xxd(byte *s, uint8_t len, void *param)
    34. {
    35.     uint8_t i;
    36.     uint16_t *line = (uint16_t *)param;
    37.     fprintf(stdout, "%08x:", *line << 4);
    38.     for (i = 0; i+2 < len; i+=2) {
    39.         fprintf(stdout, " %02x%02x", s[i], s[i+1]);
    40.     }
    41.     if (i fprintf(stdout, " %02x", s[i]); i+= 1;}
    42.     if (i fprintf(stdout, "%02x", s[i]); i+=1;}
    43.     if (i < 16 && 0x00 != (i & 0x01)) { fputs("  ", stdout); i+=1;}
    44.     for (; i <16; i+= 2) {
    45.         fputs("     ", stdout); /* space * 5 */
    46.     }
    47.     fputs("  ", stdout);
    48.     for (i = 0; i 
    49.         if (s[i] <0x20 || s[i] > 0x7e) {
    50.             fputc('.', stdout);
    51.         } else {
    52.             fputc(s[i], stdout);
    53.         }
    54.     }
    55.     fputs("\r\n", stdout);
    56.     *line += 1;
    57.     return i;
    58. }

    运行输出:

    dataLen=4
    00000000: 7b96 4cda                                {.L.
    dataLen=4
    00000000: 716c 51bd                                qlQ.
    n1->data=123.150.76.218
    n1->data=113.108.81.189

    qq.com的2个ip地址为 123,150.76.218, 113.108.81.189

    用wireshark查看:

     

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  • 原文地址：https://blog.csdn.net/fareast_mzh/article/details/132948360