Update IP parsing based on netlink address attribute format #19
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…s always existed Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>
Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>
Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>
Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>
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| @@ -351,17 +352,6 @@ func assembleService(attrs []syscall.NetlinkRouteAttr) (*Service, error) { | |||
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| } | |||
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| // in older kernels (< 3.18), the svc address family attribute may not exist so we must | |||
| // assume it based on the svc address provided. | |||
| if s.AddressFamily == 0 { | |||
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Initially added this check cause it seemed harmless but given AddressFamily for IPVS services always existed I think it would be simpler to remove this.
| // 10.0.0.1 -> [10 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0] | ||
| // For AF_INET6, the full 16 byte array is used: | ||
| // 2001:db8:3c4d:15::1a00 -> [32 1 13 184 60 77 0 21 0 0 0 0 0 0 26 0] | ||
| func getIPFamily(address []byte) (uint16, error) { |
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sorry for my question but I'm not much familiar with this code, but assuming there is no nat64 or nat46, is not possible to obtain the IP family from the virtual IP or in another place and pass it as parameter, instead of using the destination?
Line 156 in e63ad1c
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scratch my comment, this #19 (comment) has a point :)
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Yeah worth clarifying that newer kernels pass the address family attribute so this code path would never run. But for old kernels we need some way to figure out the address family so we know how to parse the address into a net.IP.
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Ran tests on CentOS 7 (3.10 kernel): |
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I mean this seems pretty gross but its only for old kernels, someone should file a bug with Red Hat to add family into their broken franeknkernel. |
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ping @arkodg @kolyshkin PTAL |
The netlink address attribute returns IPv4 addresses in a way that is not easily consumable by Go's standard net library. For example, an IPv4 address like 10.0.0.1 is received from netlink as:
which Go's net library considers an IPv6 address based on this check.
Due to this limitation, this PR updates the address family check for destination servers (only in older kernels < 3.18) so that any address attribute value that has 12 leading 0s is considered an IPv4 address, otherwise we assume the address family is IPv6.