From: CarlosRivera <CarlosRivera@...>
Date: 2004-10-03T15:04:56+09:00
Subject: Socket::gethostbyname()

I have done the following:

irb(main):103:0> response = Socket::gethostbyname('www.ebay.com')
=> ["pages.ebay.com", [], 2, 
"\020\002\000\000B\207\300X\000\000\000\000\000\000\000\000", 
"\020\002\000\000B\207\320X\000\000\000\000\000\000\000\000", 
"\020\002\000\000B\207\320e\000\000\000\000\000\000\000\000", 
"\020\002\000\000B\207\300W\000\000\000\000\000\000\000\000"]
irb(main):104:0>

What exactly are the 4 entries that are after the 2 in the array?  From 
looking at the man page for gethostbyname(), it should return something 
resembling:

    struct  hostent {
         char    *h_name;        /* official name of host */
         char    **h_aliases;    /* alias list */
         int     h_addrtype;     /* host address type */
         int     h_length;       /* length of address */
         char    **h_addr_list;  /* list of addresses from name server */
    };

I am thinking that the 4 entries after the '2' is the addr_list.  I 
would kind of expect them to be in a sub array, but back to the question 
as to the format.  From the command prompt:

[~]host www.ebay.com
www.ebay.com is an alias for pages.ebay.com.
pages.ebay.com has address 66.135.208.101
pages.ebay.com has address 66.135.192.87
pages.ebay.com has address 66.135.192.88
pages.ebay.com has address 66.135.208.88
[~]

I don't see how any of the above strings corresponds to the 4 ebay 
addresses.  I can see how parts of the string correspond to the IP address.

irb(main):162:0> a1 = response[3]
=> "\020\002\000\000B\207\320X\000\000\000\000\000\000\000\000"
irb(main):163:0> a1.each_byte {|x| puts x}
16
2
0
0
66
135
208
88
0
....
0
=> "\020\002\000\000B\207\320X\000\000\000\000\000\000\000\000"
irb(main):164:0>

I can see that there is a slightly different call 
TCPSocket::gethostbyname that returns what I am looking for:

irb(main):165:0> response = TCPSocket::gethostbyname('www.ebay.com')
=> ["pages.ebay.com", [], 2, "66.135.208.88", "66.135.208.101", 
"66.135.192.87", "66.135.192.88"]
irb(main):166:0>

I am new and I am wondering where I would look into the documentation to 
get the specifics on this.  I tried using 
http://www.ruby-doc.org/stdlib/, but I don't see enough details.  What 
exactly is the relationship between Socket and TCPSocket?