|
| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "strings" |
| 6 | + |
| 7 | + "github.com/docker/libnetwork/iptables" |
| 8 | + "github.com/docker/libnetwork/ns" |
| 9 | + "github.com/vishvananda/netlink" |
| 10 | + "github.com/vishvananda/netlink/nl" |
| 11 | + "golang.org/x/sys/unix" |
| 12 | +) |
| 13 | + |
| 14 | +const ( |
| 15 | + bridgePrefix = "kt" |
| 16 | + bridgeLen = 12 |
| 17 | +) |
| 18 | + |
| 19 | +func getBridgeName(netID string) string { |
| 20 | + return bridgePrefix + "-" + netID[:bridgeLen] |
| 21 | +} |
| 22 | + |
| 23 | +func createBridge(netID string) (string, error) { |
| 24 | + bridgeName := getBridgeName(netID) |
| 25 | + |
| 26 | + exists, err := bridgeInterfaceExists(bridgeName) |
| 27 | + if err != nil { |
| 28 | + return "", err |
| 29 | + } |
| 30 | + |
| 31 | + if !exists { |
| 32 | + linkAttrs := netlink.NewLinkAttrs() |
| 33 | + linkAttrs.Name = bridgeName |
| 34 | + |
| 35 | + if err := netlink.LinkAdd(&netlink.Bridge{ |
| 36 | + LinkAttrs: linkAttrs, |
| 37 | + }); err != nil { |
| 38 | + return "", err |
| 39 | + } |
| 40 | + } |
| 41 | + |
| 42 | + bridge, err := netlink.LinkByName(bridgeName) |
| 43 | + if err != nil { |
| 44 | + return "", err |
| 45 | + } |
| 46 | + |
| 47 | + var bridgeRule = []string{"-i", bridgeName, "-o", bridgeName, "-j", "ACCEPT"} |
| 48 | + |
| 49 | + // Install rule in IPv4 |
| 50 | + var iptablev4 = iptables.GetIptable(iptables.IPv4) |
| 51 | + if err := iptablev4.ProgramRule(iptables.Filter, "FORWARD", iptables.Append, bridgeRule); err != nil { |
| 52 | + return "", err |
| 53 | + } |
| 54 | + |
| 55 | + // Install rule in IPv6 |
| 56 | + var iptablev6 = iptables.GetIptable(iptables.IPv6) |
| 57 | + if err := iptablev6.ProgramRule(iptables.Filter, "FORWARD", iptables.Append, bridgeRule); err != nil { |
| 58 | + return "", err |
| 59 | + } |
| 60 | + |
| 61 | + if err := patchBridge(bridge); err != nil { |
| 62 | + return "", err |
| 63 | + } |
| 64 | + |
| 65 | + return bridgeName, nil |
| 66 | +} |
| 67 | + |
| 68 | +func patchBridge(bridge netlink.Link) error { |
| 69 | + // Creates a new RTM_NEWLINK request |
| 70 | + // NLM_F_ACK is used to receive acks when operations are executed |
| 71 | + req := nl.NewNetlinkRequest(unix.RTM_NEWLINK, unix.NLM_F_ACK) |
| 72 | + |
| 73 | + // Search for the bridge interface by its index (and bring it UP too) |
| 74 | + msg := nl.NewIfInfomsg(unix.AF_UNSPEC) |
| 75 | + msg.Change = unix.IFF_UP |
| 76 | + msg.Flags = unix.IFF_UP |
| 77 | + msg.Index = int32(bridge.Attrs().Index) |
| 78 | + req.AddData(msg) |
| 79 | + |
| 80 | + // Patch ageing_time and group_fwd_mask |
| 81 | + linkInfo := nl.NewRtAttr(unix.IFLA_LINKINFO, nil) |
| 82 | + linkInfo.AddRtAttr(nl.IFLA_INFO_KIND, nl.NonZeroTerminated(bridge.Type())) |
| 83 | + |
| 84 | + data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil) |
| 85 | + data.AddRtAttr(nl.IFLA_BR_AGEING_TIME, nl.Uint32Attr(0)) |
| 86 | + data.AddRtAttr(nl.IFLA_BR_GROUP_FWD_MASK, nl.Uint16Attr(0xfff8)) |
| 87 | + |
| 88 | + req.AddData(linkInfo) |
| 89 | + |
| 90 | + // Execute the request. NETLINK_ROUTE is used to send link updates. |
| 91 | + _, err := req.Execute(unix.NETLINK_ROUTE, 0) |
| 92 | + if err != nil { |
| 93 | + return err |
| 94 | + } |
| 95 | + |
| 96 | + return nil |
| 97 | +} |
| 98 | + |
| 99 | +func deleteBridge(netID string) error { |
| 100 | + bridgeName := getBridgeName(netID) |
| 101 | + |
| 102 | + bridge, err := netlink.LinkByName(bridgeName) |
| 103 | + if err != nil { |
| 104 | + return err |
| 105 | + } |
| 106 | + |
| 107 | + if err := netlink.LinkDel(bridge); err != nil { |
| 108 | + return err |
| 109 | + } |
| 110 | + |
| 111 | + var bridgeRule = []string{"-i", bridgeName, "-o", bridgeName, "-j", "ACCEPT"} |
| 112 | + |
| 113 | + // Delete rule in IPv4 |
| 114 | + var iptablev4 = iptables.GetIptable(iptables.IPv4) |
| 115 | + if err := iptablev4.ProgramRule(iptables.Filter, "FORWARD", iptables.Delete, bridgeRule); err != nil { |
| 116 | + return err |
| 117 | + } |
| 118 | + |
| 119 | + // Delete rule in IPv6 |
| 120 | + var iptablev6 = iptables.GetIptable(iptables.IPv6) |
| 121 | + if err := iptablev6.ProgramRule(iptables.Filter, "FORWARD", iptables.Delete, bridgeRule); err != nil { |
| 122 | + return err |
| 123 | + } |
| 124 | + |
| 125 | + return nil |
| 126 | +} |
| 127 | + |
| 128 | +func attachInterfaceToBridge(bridgeName string, interfaceName string) error { |
| 129 | + bridge, err := netlink.LinkByName(bridgeName) |
| 130 | + if err != nil { |
| 131 | + return err |
| 132 | + } |
| 133 | + |
| 134 | + iface, err := netlink.LinkByName(interfaceName) |
| 135 | + if err != nil { |
| 136 | + return err |
| 137 | + } |
| 138 | + |
| 139 | + if err := netlink.LinkSetMaster(iface, bridge); err != nil { |
| 140 | + return err |
| 141 | + } |
| 142 | + if err := netlink.LinkSetUp(iface); err != nil { |
| 143 | + return err |
| 144 | + } |
| 145 | + |
| 146 | + return nil |
| 147 | +} |
| 148 | + |
| 149 | +func bridgeInterfaceExists(name string) (bool, error) { |
| 150 | + nlh := ns.NlHandle() |
| 151 | + link, err := nlh.LinkByName(name) |
| 152 | + |
| 153 | + if err != nil { |
| 154 | + if strings.Contains(err.Error(), "Link not found") { |
| 155 | + return false, nil |
| 156 | + } |
| 157 | + |
| 158 | + return false, fmt.Errorf("failed to check bridge interface existence: %v", err) |
| 159 | + } |
| 160 | + |
| 161 | + if link.Type() == "bridge" { |
| 162 | + return true, nil |
| 163 | + } |
| 164 | + |
| 165 | + return false, fmt.Errorf("existing interface %s is not a bridge", name) |
| 166 | +} |
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