rootless: support `podman network create` (CNI-in-slirp4netns)

Usage:
```
$ podman network create foo
$ podman run -d --name web --hostname web --network foo nginx:alpine
$ podman run --rm --network foo alpine wget -O - http://web.dns.podman
Connecting to web.dns.podman (10.88.4.6:80)
...
<h1>Welcome to nginx!</h1>
...
```

See contrib/rootless-cni-infra for the design.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

1 files changed, 4 insertions, 0 deletions

diff --git a/pkg/domain/infra/abi/network.go b/pkg/domain/infra/abi/network.go
index c06714cbb..807e4b272 100644
--- a/pkg/domain/infra/abi/network.go
+++ b/pkg/domain/infra/abi/network.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -216,6 +217,9 @@ func createBridge(r *libpod.Runtime, name string, options entities.NetworkCreate
 	if err != nil {
 		return "", err
 	}
+	if err := os.MkdirAll(network.GetCNIConfDir(runtimeConfig), 0755); err != nil {
+		return "", err
+	}
 	cniPathName := filepath.Join(network.GetCNIConfDir(runtimeConfig), fmt.Sprintf("%s.conflist", name))
 	err = ioutil.WriteFile(cniPathName, b, 0644)
 	return cniPathName, err