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Increment IP addrress safely #258

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Dec 15, 2018
Merged

Increment IP addrress safely #258

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41 changes: 30 additions & 11 deletions pkg/networkutils/network.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
package networkutils

import (
"encoding/binary"
"fmt"
"io"
"math"
Expand Down Expand Up @@ -507,22 +508,24 @@ func setupENINetwork(eniIP string, eniMAC string, eniTable int, eniSubnetCIDR st

deviceNumber := link.Attrs().Index

_, gw, err := net.ParseCIDR(eniSubnetCIDR)
_, ipnet, err := net.ParseCIDR(eniSubnetCIDR)

if err != nil {
return errors.Wrapf(err, "eni network setup: invalid ipv4 cidr block %s", eniSubnetCIDR)
}

// TODO: big/little endian: convert subnet to gw
gw.IP[3] = gw.IP[3] + 1
gw, err := incrementIPv4Addr(ipnet.IP)
if err != nil {
return errors.Wrapf(err, "eni network setup: failed to define gateway address from %v", ipnet.IP)
}

log.Debugf("Setting up ENI's default gateway %v", gw.IP)
log.Debugf("Setting up ENI's default gateway %v", gw)

for _, r := range []netlink.Route{
// Add a direct link route for the host's ENI IP only
{
LinkIndex: deviceNumber,
Dst: &net.IPNet{IP: gw.IP, Mask: net.CIDRMask(32, 32)},
Dst: &net.IPNet{IP: gw, Mask: net.CIDRMask(32, 32)},
Scope: netlink.SCOPE_LINK,
Table: eniTable,
},
Expand All @@ -531,7 +534,7 @@ func setupENINetwork(eniIP string, eniMAC string, eniTable int, eniSubnetCIDR st
LinkIndex: deviceNumber,
Dst: &net.IPNet{IP: net.IPv4zero, Mask: net.CIDRMask(0, 32)},
Scope: netlink.SCOPE_UNIVERSE,
Gw: gw.IP,
Gw: gw,
Table: eniTable,
},
} {
Expand All @@ -550,13 +553,13 @@ func setupENINetwork(eniIP string, eniMAC string, eniTable int, eniSubnetCIDR st
retry++
if retry > maxRetryRouteAdd {
log.Errorf("Failed to add route %s/0 via %s table %d",
r.Dst.IP.String(), gw.IP.String(), eniTable)
r.Dst.IP.String(), gw.String(), eniTable)
return errors.Wrapf(err,
"eni network setup: failed unable to add route %s/0 via %s table %d",
r.Dst.IP.String(), gw.IP.String(), eniTable)
r.Dst.IP.String(), gw.String(), eniTable)
}
log.Debugf("Not able to add route route %s/0 via %s table %d (attempt %d/%d)",
r.Dst.IP.String(), gw.IP.String(), eniTable,
r.Dst.IP.String(), gw.String(), eniTable,
retry, maxRetryRouteAdd)
time.Sleep(retryRouteAddInterval)
} else if isRouteExistsError(err) {
Expand All @@ -567,10 +570,10 @@ func setupENINetwork(eniIP string, eniMAC string, eniTable int, eniSubnetCIDR st
break
} else {
return errors.Wrapf(err, "eni network setup: unable to add route %s/0 via %s table %d",
r.Dst.IP.String(), gw.IP.String(), eniTable)
r.Dst.IP.String(), gw.String(), eniTable)
}
} else {
log.Debugf("Successfully added route route %s/0 via %s table %d", r.Dst.IP.String(), gw.IP.String(), eniTable)
log.Debugf("Successfully added route route %s/0 via %s table %d", r.Dst.IP.String(), gw.String(), eniTable)
break
}
}
Expand Down Expand Up @@ -598,6 +601,22 @@ func setupENINetwork(eniIP string, eniMAC string, eniTable int, eniSubnetCIDR st
return nil
}

// incremetnIPv4Addr returns incremented IPv4 address
func incrementIPv4Addr(ip net.IP) (net.IP, error) {
ip4 := ip.To4()
if ip4 == nil {
return nil, fmt.Errorf("%q is not a valid IPv4 Address.", ip)
}
int_ip := binary.BigEndian.Uint32([]byte(ip4))
if int_ip == (1<<32 - 1) {
return nil, fmt.Errorf("%q will be overflowed", ip)
}
int_ip++
bytes := make([]byte, 4)
binary.BigEndian.PutUint32(bytes, int_ip)
return net.IP(bytes), nil
}

// isNotExistsError returns true if the error type is syscall.ESRCH
// This helps us determine if we should ignore this error as the route
// that we want to cleanup has been deleted already routing table
Expand Down
26 changes: 26 additions & 0 deletions pkg/networkutils/network_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,32 @@ func TestSetupHostNetworkNodePortEnabled(t *testing.T) {
assert.Equal(t, mockFile{closed: true, data: "2"}, mockRPFilter)
}

func TestIncrementIPv4Addr(t *testing.T) {
testCases := []struct {
name string
ip net.IP
expected net.IP
err bool
}{
{"increment", net.IPv4(10, 0, 0, 1), net.IPv4(10, 0, 0, 2).To4(), false},
{"carry up 1", net.IPv4(10, 0, 0, 255), net.IPv4(10, 0, 1, 0).To4(), false},
{"carry up 2", net.IPv4(10, 0, 255, 255), net.IPv4(10, 1, 0, 0).To4(), false},
{"overflow", net.IPv4(255, 255, 255, 255), nil, true},
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Nice test cases.

}

for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
result, err := incrementIPv4Addr(tc.ip)
if tc.err {
assert.Error(t, err)
} else {
assert.NoError(t, err)
}
assert.Equal(t, tc.expected, result, tc.name)
})
}
}

type mockIptables struct {
// dataplaneState is a map from table name to chain name to slice of rulespecs
dataplaneState map[string]map[string][][]string
Expand Down