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undo CL 4557058 / b4c2ffae7034

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Using the getaddrinfo order is only okay if we
are smart enough to try multiple addresses in Dial.
Since the code does not do that, we must make
the right first choice, regardless of what getaddrinfo
does, and more often that not that means using the
IPv4 address, even on IPv6 systems.  With the CL
applied, gotest fails in package net on OS X.

helix.cam=; gotest
...
--- FAIL: net.TestDialGoogleIPv4 (1.05 seconds)
        -- 74.125.226.179:80 --
        -- www.google.com:80 --
        Dial("tcp", "", "www.google.com:80") = _, dial tcp [2001:4860:800f::69]:80: address family not supported by protocol family
        -- 74.125.226.179:http --
        -- www.google.com:http --
        Dial("tcp", "", "www.google.com:http") = _, dial tcp [2001:4860:800f::69]:80: address family not supported by protocol family
        -- 074.125.226.179:0080 --
        -- [::ffff:74.125.226.179]:80 --
        -- [::ffff:4a7d:e2b3]:80 --
        -- [0:0:0:0:0000:ffff:74.125.226.179]:80 --
        -- [0:0:0:0:000000:ffff:74.125.226.179]:80 --
        -- [0:0:0:0:0:ffff::74.125.226.179]:80 --
FAIL
gotest: "./6.out" failed: exit status 1

««« original CL description
net: name-based destination address selection

getaddrinfo() orders the addresses according to RFC 3484.

This means when IPv6 is working on a host we get results like:
    []string = {"2001:4810::110", "66.117.47.214"}

and when it's not working we get:
    []string = {"66.117.47.214", "2001:4810::110"}

thus can drop firstFavoriteAddr.

This also means /etc/gai.conf works on relevant systems.

R=rsc, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/4557058

»»»

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/4532101
This commit is contained in:
Russ Cox 2011-06-01 15:49:57 -04:00
parent e0cca45fcb
commit 16dbf2182c
2 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/pkg/net/iprawsock.go
View File

@ -253,7 +253,7 @@ func hostToIP(net, host string) (ip IP, err os.Error) {
err = err1
goto Error
}
addr = firstSupportedAddr(filter, addrs)
addr = firstFavoriteAddr(filter, addrs)
if addr == nil {
// should not happen
err = &AddrError{"LookupHost returned no suitable address", addrs[0]}

19
src/pkg/net/ipsock.go
View File

@ -98,6 +98,23 @@ func favoriteAddrFamily(net string, raddr, laddr sockaddr, mode string) int {
return syscall.AF_INET6
}
func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
if filter == anyaddr {
// We'll take any IP address, but since the dialing code
// does not yet try multiple addresses, prefer to use
// an IPv4 address if possible. This is especially relevant
// if localhost resolves to [ipv6-localhost, ipv4-localhost].
// Too much code assumes localhost == ipv4-localhost.
addr = firstSupportedAddr(ipv4only, addrs)
if addr == nil {
addr = firstSupportedAddr(anyaddr, addrs)
}
} else {
addr = firstSupportedAddr(filter, addrs)
}
return
}
func firstSupportedAddr(filter func(IP) IP, addrs []string) IP {
for _, s := range addrs {
if addr := filter(ParseIP(s)); addr != nil {
@ -276,7 +293,7 @@ func hostPortToIP(net, hostport string) (ip IP, iport int, err os.Error) {
err = err1
goto Error
}
addr = firstSupportedAddr(filter, addrs)
addr = firstFavoriteAddr(filter, addrs)
if addr == nil {
// should not happen
err = &AddrError{"LookupHost returned no suitable address", addrs[0]}