dhcp: make netns path absolute prior to RPC

The dhcp daemon may be running with a different cwd
and so the netns paths need to be absolute. This patch
also refactors the code to pull out the common, RPC
parts, out into a separate function.

diff --git a/plugins/ipam/dhcp/main.go b/plugins/ipam/dhcp/main.go
index 2bc6625..ca80271 100644 (file)
--- a/plugins/ipam/dhcp/main.go
+++ b/plugins/ipam/dhcp/main.go
@@ -18,6 +18,7 @@ import (
        "fmt"
        "net/rpc"
        "os"
+       "path/filepath"
 
        "github.com/appc/cni/pkg/plugin"
        "github.com/appc/cni/pkg/skel"
@@ -34,30 +35,38 @@ func main() {
 }
 
 func cmdAdd(args *skel.CmdArgs) error {
-       client, err := rpc.DialHTTP("unix", socketPath)
-       if err != nil {
-               return fmt.Errorf("error dialing DHCP daemon: %v", err)
-       }
-
-       result := &plugin.Result{}
-       err = client.Call("DHCP.Allocate", args, result)
-       if err != nil {
-               return fmt.Errorf("error calling DHCP.Add: %v", err)
+       result := plugin.Result{}
+       if err := rpcCall("DHCP.Allocate", args, &result); err != nil {
+               return err
        }
-
        return result.Print()
 }
 
 func cmdDel(args *skel.CmdArgs) error {
+       result := struct{}{}
+       if err := rpcCall("DHCP.Release", args, &result); err != nil {
+               return fmt.Errorf("error dialing DHCP daemon: %v", err)
+       }
+       return nil
+}
+
+func rpcCall(method string, args *skel.CmdArgs, result interface{}) error {
        client, err := rpc.DialHTTP("unix", socketPath)
        if err != nil {
                return fmt.Errorf("error dialing DHCP daemon: %v", err)
        }
 
-       dummy := struct{}{}
-       err = client.Call("DHCP.Release", args, &dummy)
+       // The daemon may be running under a different working dir
+       // so make sure the netns path is absolute.
+       netns, err := filepath.Abs(args.Netns)
+       if err != nil {
+               return fmt.Errorf("failed to make %q an absolute path: %v", args.Netns, err)
+       }
+       args.Netns = netns
+
+       err = client.Call(method, args, result)
        if err != nil {
-               return fmt.Errorf("error calling DHCP.Del: %v", err)
+               return fmt.Errorf("error calling %v: %v", method, err)
        }
 
        return nil