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Assume the address family based on the destination address #15

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Merged
justincormack merged 1 commit into from
Apr 27, 2020
Merged

Assume the address family based on the destination address #15

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22 changes: 22 additions & 0 deletions netlink.go
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Original file line number Diff line number Diff line change
Expand Up @@ -351,6 +351,17 @@ func assembleService(attrs []syscall.NetlinkRouteAttr) (*Service, error) {

}

// in older kernels (< 3.18), the svc address family attribute may not exist so we must
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@andrewsykim andrewsykim Mar 31, 2020

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AFAICT this is only an issue for destination addresses since IPVS_DEST_ATTR_ADDR_FAMILY was added later while IPVS_SVC_ATTR_AF had always existed, but this extra check doesn't seem to hurt.

// assume it based on the svc address provided.
if s.AddressFamily == 0 {
addr := (net.IP)(addressBytes)
if addr.To4() != nil {
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@andrewsykim andrewsykim Apr 28, 2020

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In running a few more tests, I realized this won't work because To4() checks the last 4 bytes for v4 addresses and leading 0 but netlink returns IPv4 addresses in the first 4 bytes.

Will follow-up with a fix.

s.AddressFamily = syscall.AF_INET
} else {
s.AddressFamily = syscall.AF_INET6
}
}

// parse Address after parse AddressFamily incase of parseIP error
if addressBytes != nil {
ip, err := parseIP(addressBytes, s.AddressFamily)
Expand Down Expand Up @@ -458,6 +469,17 @@ func assembleDestination(attrs []syscall.NetlinkRouteAttr) (*Destination, error)
}
}

// in older kernels (< 3.18), the destination address family attribute doesn't exist so we must
// assume it based on the destination address provided.
if d.AddressFamily == 0 {
addr := (net.IP)(addressBytes)
if addr.To4() != nil {
d.AddressFamily = syscall.AF_INET
} else {
d.AddressFamily = syscall.AF_INET6
}
}

// parse Address after parse AddressFamily incase of parseIP error
if addressBytes != nil {
ip, err := parseIP(addressBytes, d.AddressFamily)
Expand Down