2011-05-12 166 views
0
extern "C" int RTinet_lookup(const char * host,RTinet_address *address,RTinet_port port) 
{ 
    struct addrinfo,*res; 
    int errcode; 
    char addrstr[INET6_ADDRSTRLEN]; 


    memset (&hints, 0, sizeof (hints)); 
    hints.ai_family = AF_UNSPEC; 
    hints.ai_socktype = SOCK_STREAM; 
    hints.ai_protocol = IPPROTO_TCP; 
    hints.ai_flags |= AI_CANONNAME; 

    errcode = getaddrinfo (host, NULL , &hints, &res); 
    if (errcode != 0) 
    { 
     INFO("getaddrinfo"); 
     return -1; 
    } 
    INFO(STR("Host: %s", host)); 
    if(res == NULL) 
    { 
    INFO(STR("NULL VALUE OF RES")); 
    } 
    else 
    {INFO(STR("IN ELSE PART")); 
    while (res) 
    { 
     INFO(STR("Inside while condition with res ")); 
     switch (res->ai_family) 
     { 
     case AF_INET: 
      inet_ntop(AF_INET, &((struct sockaddr_in *) res->ai_addr)->sin_addr,addrstr, INET_ADDRSTRLEN); 
      break; 
     case AF_INET6: 
      inet_ntop(AF_INET6, &((struct sockaddr_in6 *) res->ai_addr)->sin6_addr ,addrstr, INET6_ADDRSTRLEN); 
      break; 
     } 
     res = res->ai_next; 
    } 
    } 
    INFO(STR("IPv%d address: %s ", res->ai_family == AF_INET6 ? 6 : 4, addrstr)); 
    return 1; 
} 

在這裏我通過"::1"作爲主機地址,這是一個IPV6形式。但在跟蹤我越來越沒有得到想要的輸出

Host: ::1  
IPv4 address: ::1 

爲什麼這是採取IPv4?它應該採取的IPv6的地址族應AF_INET6在這種情況下

回答

1

res指向NULL,所以你最後的print語句是無效的,因爲你承擔ai_family != AF_INET6必須AF_INET

編輯:爲了進一步說明這裏就是一個代碼問題,可消除非相關要點:

while (res) 
{ 
    res = res->ai_next; 
} 
INFO(STR("IPv%d address: %s ", res->ai_family == AF_INET6 ? 6 : 4, addrstr)); 

問問自己是什麼res值時爲完成while循環。

+0

@ Steve-o ...你能否提出爲什麼它指向null以及如何糾正它,以便獲得所需的輸出。謝謝 – 2011-05-13 05:05:48

+0

@ Steve-o ...但是因爲我保留了一個條件,如果res == NULL,那麼INFO(STR(「NULL VALUE OF RES」)); 應該打印出來,但是這條語句不會出現在日誌中。那麼你對此有什麼建議?謝謝 – 2011-05-13 05:15:51

+0

@Kundan,你在'res'上有一個'while'循環,直到它是'NULL',然後你試着讀'res-> ai_family'。 – 2011-05-13 12:51:50