1 files changed, 66 insertions, 0 deletions
diff --git a/pim/cmd/caldavfs/principal.go b/pim/cmd/caldavfs/principal.go
new file mode 100644
index 0000000..b5d6558
--- /dev/null
+++ b/pim/cmd/caldavfs/principal.go
@@ -0,0 +1,66 @@
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+// findPrincipal asks the endpoint who we are.
+//
+// go-webdav does this too, but it resolves the request path with
+// path.Join, which drops a trailing slash: a client pointed at /dav/
+// ends up asking about /dav, and Cyrus answers 405 for that exact
+// spelling while answering 207 for /dav/. Deeper paths tolerate either,
+// so only this first request needs doing by hand.
+func findPrincipal(endpoint, user, pass string) (string, error) {
+	body := `<?xml version="1.0" encoding="utf-8"?>` +
+		`<d:propfind xmlns:d="DAV:"><d:prop><d:current-user-principal/></d:prop></d:propfind>`
+
+	req, err := http.NewRequest("PROPFIND", endpoint, strings.NewReader(body))
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Depth", "0")
+	req.Header.Set("Content-Type", "application/xml; charset=utf-8")
+	req.SetBasicAuth(user, pass)
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusMultiStatus {
+		return "", fmt.Errorf("%s: %s", endpoint, resp.Status)
+	}
+
+	// Spelled out rather than using encoding/xml's "a>b" path
+	// shorthand, which does not carry namespaces through.
+	type href struct {
+		Href string `xml:"DAV: href"`
+	}
+	type prop struct {
+		Principal href `xml:"DAV: current-user-principal"`
+	}
+	type propstat struct {
+		Prop prop `xml:"DAV: prop"`
+	}
+	type response struct {
+		Propstats []propstat `xml:"DAV: propstat"`
+	}
+	var ms struct {
+		Responses []response `xml:"DAV: response"`
+	}
+	if err := xml.NewDecoder(resp.Body).Decode(&ms); err != nil {
+		return "", err
+	}
+	for _, r := range ms.Responses {
+		for _, ps := range r.Propstats {
+			if h := strings.TrimSpace(ps.Prop.Principal.Href); h != "" {
+				return h, nil
+			}
+		}
+	}
+	return "", fmt.Errorf("%s: no current-user-principal", endpoint)
+}