Merge pull request #201 from Bytom/v0.1

[bytom/vapor.git] / p2p / external_ip.go

diff --git a/p2p/external_ip.go b/p2p/external_ip.go
new file mode 100644 (file)
index 0000000..5c2c90c
--- /dev/null
+++ b/p2p/external_ip.go
@@ -0,0 +1,47 @@
+package p2p
+
+import (
+       "net"
+)
+
+// ExternalIPv4 returns the first IPv4 available.
+func ExternalIPv4() (string, error) {
+       ifaces, err := net.Interfaces()
+       if err != nil {
+               return "", err
+       }
+
+       for _, iface := range ifaces {
+               // interface down
+               if iface.Flags&net.FlagUp == 0 {
+                       continue
+               }
+               // loopback interface
+               if iface.Flags&net.FlagLoopback != 0 {
+                       continue
+               }
+               addrs, err := iface.Addrs()
+               if err != nil {
+                       return "", err
+               }
+
+               for _, addr := range addrs {
+                       var ip net.IP
+                       switch v := addr.(type) {
+                       case *net.IPNet:
+                               ip = v.IP
+                       case *net.IPAddr:
+                               ip = v.IP
+                       }
+                       if ip == nil || ip.IsLoopback() {
+                               continue
+                       }
+                       ip = ip.To4()
+                       if ip == nil {
+                               continue // not an ipv4 address
+                       }
+                       return ip.String(), nil
+               }
+       }
+       return "127.0.0.1", nil
+}