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Socket.gethostbyname #2125

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Socket.gethostbyname #2125

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45a1371
Update spec library/socket/socket/gethostbyname.
sdaubert Jan 14, 2013
9bda567
Update Socket.gethostbyname to respect two new specs.
sdaubert Jan 14, 2013
77a888c
Pass spec gethostbyname cleanly.
sdaubert Jan 18, 2013
e10cc24
Socket.gethostbyname
sdaubert Jan 18, 2013
e956c23
Update Socket.gethostbyname to respect two new specs.
sdaubert Jan 14, 2013
f5e460f
Merge branch 'socket.gethostbyname' of github.com:sdaubert/rubinius i…
sdaubert Jan 18, 2013
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12 changes: 11 additions & 1 deletion lib/18/socket.rb
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Expand Up @@ -610,7 +610,17 @@ def self.gethostbyname(hostname)
alternatives = []
addrinfos.each do |a|
alternatives << a[2] unless a[2] == hostname
addresses << a[3] if a[4] == family
# transform addresses to packed strings
if a[4] == family
sockaddr = Socket.sockaddr_in(1, a[3])
if sockaddr.length == 16
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We shouldn't just check the length and thus assume a certain layout. It's better to switch on the family, whether it's AF_INET or AF_INET6

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Good point.

# IPv4 address
addresses << sockaddr[4, 4]
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We should also find another way of know which bytes are what. We can't be sure about the exact byte layouts of these so we shouldn't hard code these offsets here.

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But these offsets are not magic : they come from C struct definitions:

/* man 7 ip */
           struct sockaddr_in {
               sa_family_t    sin_family;   /* AF_INET */
               in_port_t      sin_port;      /* port number */
               struct in_addr sin_addr;   /* internet address */
           };

           struct in_addr {
               uint32_t       s_addr;
           };

and

/* man 7 ipv6 */
           struct sockaddr_in6 {
               sa_family_t     sin6_family;   /* AF_INET6 */
               in_port_t       sin6_port      /* port number */;
               uint32_t        sin6_flowinfo; /* flow information */
               struct in6_addr sin6_addr;     /* IPv6 adress */
               uint32_t        sin6_scope_id; /* Scope ID */
           };

           struct in6_addr {
               unsigned char   s6_addr[16];
           };

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That's exactly my point :). We should get these offsets from struct definitions for these types and not hard code these offsets. They might be different due to platform alignment, type sizes etc. that's why we should depend on what information the platform supplies for these types.

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OK. So we can use Socket::SockAddr_In. SockAddr_In#offset_of gives offset of sockaddr_in* fields. But i don't known how to get their size.

else
# Ipv6 address
addresses << sockaddr[8, 16]
end
end
end

[hostname, alternatives.uniq, family] + addresses.uniq
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12 changes: 11 additions & 1 deletion lib/19/socket.rb
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Expand Up @@ -687,7 +687,17 @@ def self.gethostbyname(hostname)
alternatives = []
addrinfos.each do |a|
alternatives << a[2] unless a[2] == hostname
addresses << a[3] if a[4] == family
# transform addresses to packed strings
if a[4] == family
sockaddr = Socket.sockaddr_in(1, a[3])
if sockaddr.length == 16
# IPv4 address
addresses << sockaddr[4, 4]
else
# Ipv6 address
addresses << sockaddr[8, 16]
end
end
end

[hostname, alternatives.uniq, family] + addresses.uniq
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12 changes: 11 additions & 1 deletion lib/20/socket.rb
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Open in desktop
Expand Up @@ -687,7 +687,17 @@ def self.gethostbyname(hostname)
alternatives = []
addrinfos.each do |a|
alternatives << a[2] unless a[2] == hostname
addresses << a[3] if a[4] == family
# transform addresses to packed strings
if a[4] == family
sockaddr = Socket.sockaddr_in(1, a[3])
if sockaddr.length == 16
# IPv4 address
addresses << sockaddr[4, 4]
else
# Ipv6 address
addresses << sockaddr[8, 16]
end
end
end

[hostname, alternatives.uniq, family] + addresses.uniq
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10 changes: 10 additions & 0 deletions spec/ruby/library/socket/socket/gethostbyname_spec.rb
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Expand Up @@ -13,4 +13,14 @@
addr = Socket.gethostbyname('<any>').first;
addr.should == "0.0.0.0"
end

it "returns address list in pack format (IPv4)" do
laddr = Socket.gethostbyname('127.0.0.1')[3..-1];
laddr.should == ["\x7f\x00\x00\x01"]
end

it "returns address list in pack format (IPv6)" do
laddr = Socket.gethostbyname('::1')[3..-1]
laddr.should == ["\x00" * 15 + "\x01"]
end
end