1 files changed, 94 insertions, 0 deletions

diff --git a/network.go b/network.go
new file mode 100644
index 0000000..d78a57d
--- /dev/null
+++ b/network.go
@@ -0,0 +1,94 @@
+package main
+
+import (
+        "errors"
+        "net"
+        "os"
+        "strings"
+
+        jww "github.com/spf13/jwalterweatherman"
+)
+
+type interfaceContext struct {
+        PrimaryIP       *net.IP
+        MacAddr         *net.HardwareAddr
+        PrimaryHostname *string
+}
+
+func interfaceIsUsable(i *net.Interface) bool {
+        if i.Flags&net.FlagLoopback != 0 {
+                return false
+        }
+
+        if i.Flags&net.FlagUp == 0 {
+                return false
+        }
+
+        addrs, err := i.Addrs()
+        if err != nil || len(addrs) == 0 {
+                return false
+        }
+
+        if strings.HasPrefix(i.Name, "docker") {
+                return false
+        }
+
+        return true
+}
+
+func getPrimaryInterface() (*net.Interface, error) {
+        ifaces, err := net.Interfaces()
+        if err != nil {
+                return nil, err
+        }
+
+        if len(ifaces) == 0 {
+                return nil, errors.New("no interfaces found")
+        }
+
+        var iface net.Interface
+        for _, iface = range ifaces {
+                if !interfaceIsUsable(&iface) {
+                        continue
+                } else {
+                        break
+                }
+        }
+
+        if interfaceIsUsable(&iface) {
+                return &iface, nil
+        } else {
+                return nil, errors.New("no usable interfaces found")
+        }
+}
+
+func getInterfaceContext() (*interfaceContext, error) {
+        iface, err := getPrimaryInterface()
+        if err != nil {
+                return nil, err
+        }
+
+        // Validated to have at least this in interfaceIsUsable
+        addrs, err := iface.Addrs()
+        if err != nil {
+                return nil, err
+        }
+
+        primaryAddr := addrs[0].String()
+        primaryIP, _, err := net.ParseCIDR(primaryAddr)
+        if err != nil {
+                return nil, err
+        }
+
+        name, err := os.Hostname()
+        if err != nil {
+                jww.ERROR.Printf("Unable to resolve hostname, using localhost: %s", err.Error())
+                name = "localhost"
+        }
+
+        return &interfaceContext{
+                PrimaryIP:       &primaryIP,
+                MacAddr:         &iface.HardwareAddr,
+                PrimaryHostname: &name,
+        }, nil
+}