netlink

To use the netlink library in your Go project, use the go get command to fetch the package from GitHub.

go get github.com/vishvananda/netlink

Testing the library requires root privileges and the netns dependency. To run tests, use sudo -E go test to ensure environment variables are preserved.

go get github.com/vishvananda/netns
sudo -E go test github.com/vishvananda/netlink

The netlink package provides a Go API for managing Linux ipset structures via netlink. You can create, destroy, flush, swap, and list ipsets, as well as add, delete, or test for specific entries within a set.

Key operations include:

• IpsetCreate: Create a new set with specific options.
• IpsetAdd / IpsetDel: Manage entries in a set.
• IpsetList / IpsetListAll: Retrieve set information and entries.
• IpsetTest: Check if an entry exists in a set.

You can create a new bridge interface using netlink.LinkAdd() and attach an existing interface (like eth1) to it using netlink.LinkSetMaster().

When defining link attributes, it is recommended to use the netlink.NewLinkAttrs() constructor. This ensures that TxQLen is set to -1, allowing the kernel to apply its own default values. If you use a literal struct initialization like LinkAttrs{Name: "foo"}, TxQLen will default to 0 unless explicitly specified.

package main

import (
    "fmt"
    "github.com/vishvananda/netlink"
)

func main() {
    la := netlink.NewLinkAttrs()
    la.Name = "foo"
    mybridge := &netlink.Bridge{LinkAttrs: la}
    err := netlink.LinkAdd(mybridge)
    if err != nil  {
        fmt.Printf("could not add %s: %v\n", la.Name, err)
    }
    eth1, _ := netlink.LinkByName("eth1")
    netlink.LinkSetMaster(eth1, mybridge)
}

To add an IP address to a specific interface (e.g., lo), first retrieve the link using netlink.LinkByName(), parse the address string using netlink.ParseAddr(), and then apply it using netlink.AddrAdd().

package main

import (
    "github.com/vishvananda/netlink"
)

func main() {
    lo, _ := netlink.LinkByName("lo")
    addr, _ := netlink.ParseAddr("169.254.169.254/32")
    netlink.AddrAdd(lo, addr)
}

When creating a handle via NewHandleWithOptions, you can provide HandleOptions to customize behavior:

When creating a new vDPA device using VDPANewDev, use the VDPANewDevParams struct to specify device parameters. You can use SetBits to configure required features.

Fields:

• MACAddr: net.HardwareAddr
• MaxVQP: uint16
• MTU: uint16
• Features: uint64 (bitmask of features)

Use NewMirredAction(redirIndex int) to create a mirroring or redirection action. The MirredAction field uses MirredAct constants:

• TCA_EGRESS_REDIR: Redirect to EGRESS
• TCA_EGRESS_MIRROR: Mirror to EGRESS
• TCA_INGRESS_REDIR: Redirect to INGRESS
• TCA_INGRESS_MIRROR: Mirror to INGRESS