Retain V6 DNS server in resolv.conf; use only V4 servers for fallback #886
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Signed-off-by: Santhosh Manohar <santhosh@docker.com>
sanimej
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| type extDNSEntry struct { |
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Do you really need this ?
You will convert the configured address from string form to net.IP, then when you need to program you will convert it again back to string form just to store the IPv6 flag.
Are you using anywhere extDNEntry.IP as a net.IP ? Otherwise this seem unnecessary.
I would just check in NameServer() with isIPv6 := net.ParseIP().to4() == nil in the loop.
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I want to do the parsing once and set the v6 flag when the extDNS is populated rather than doing it on each DNS query handling which could be 100s of times.
I would just check in NameServer() with isIPv6 := net.ParseIP().to4() == nil in the loop.
Are you referring to ServeDNS() function ? That is the one handling the query where the v6 flag is checked.
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Makes sense, also I misread the code, you actually keep the IP as string, so never mind.
Got confused by the IP parsing. I, in fact, would just look for a signature since it seems the addresses are already validated, something like:
r.extDNS[i].ip = dns[i]
r.extDNS[i].isIPv6 = strings.Contains(dns[i], ":")
but this is minor, up to you.
sanimej
changed the title
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@mrjana Updated changes keep the v6 behavior same as 1.9 and embedded server will use only the v4 DNS servers to forward the requests. PTAL. |
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LGTM |
| nameservers := []string{} | ||
| for _, line := range getLines(resolvConf, []byte("#")) { | ||
| var ns = nsRegexp.FindSubmatch(line) | ||
| var ns [][]byte | ||
| if kind == netutils.IP { |
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Why not using a switch here ?
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Because if, else is just fine for small number of cases..
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So far we have been using switch for 3 else, but I see some places in the code where we have kept 3 else.
Anyway this is minor.
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LGTM |
Retain V6 DNS server in resolv.conf; use only V4 servers for fallback
Fixes #885
Signed-off-by: Santhosh Manohar santhosh@docker.com