make character case for keys in parameters map irrelevant, fixing #143

More specifically,
- introduce helper function to get maps with all keys set to lowercase,
- introduce lookup helper based on such maps and
- change lookups for CreateVolumeRequest()s and CreateVolume()s so that
  parameter keys are processed as lowercase irrespective of actual
  spelling.

Signed-off-by: Christopher J. Ruwe <cjr@cruwe.de>

pkg/common/helpers/helpers.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2020 The OpenEBS Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package helpers
+
+import (
+	"strings"
+)
+
+// Coerce the map's keys to lower case, which only works when unicode char is in
+// ASCII subset. May overwrite key-value pairs on different permutations of key
+// case as in Key and key. DON'T force values to the lower case unconditionally,
+// because values for keys such as mountpoint or keylocation are case-sensitive.
+// Note that although keys such as 'comPREssion' are accepted and processed,
+// even if they are technically invalid, updates to rectify such typing will be
+// prohibited as a forbidden update.
+func GetCaseInsensitiveMap(dict *map[string]string) map[string]string {
+	insensitiveDict := map[string]string{}
+
+	for k, v := range *dict {
+		insensitiveDict[strings.ToLower(k)] = v
+	}
+	return insensitiveDict
+}
+
+// special case of GetCaseInsensitiveMap looking up one key-value pair only
+func GetInsensitiveParameter(dict *map[string]string, key string) string {
+	insensitiveDict := GetCaseInsensitiveMap(dict)
+	return insensitiveDict[strings.ToLower(key)]
+}

pkg/driver/controller.go

@@ -27,6 +27,7 @@ import (
 	"github.com/openebs/zfs-localpv/pkg/builder/snapbuilder"
 	"github.com/openebs/zfs-localpv/pkg/builder/volbuilder"
 	errors "github.com/openebs/zfs-localpv/pkg/common/errors"
+	"github.com/openebs/zfs-localpv/pkg/common/helpers"
 	csipayload "github.com/openebs/zfs-localpv/pkg/response"
 	analytics "github.com/openebs/zfs-localpv/pkg/usage"
 	zfs "github.com/openebs/zfs-localpv/pkg/zfs"
@@ -75,17 +76,25 @@ func sendEventOrIgnore(pvName, capacity, stgType, method string) {
 func CreateZFSVolume(req *csi.CreateVolumeRequest) (string, error) {
 	volName := req.GetName()
 	size := req.GetCapacityRange().RequiredBytes
-	rs := req.GetParameters()["recordsize"]
-	bs := req.GetParameters()["volblocksize"]
-	compression := req.GetParameters()["compression"]
-	dedup := req.GetParameters()["dedup"]
-	encr := req.GetParameters()["encryption"]
-	kf := req.GetParameters()["keyformat"]
-	kl := req.GetParameters()["keylocation"]
-	pool := req.GetParameters()["poolname"]
-	tp := req.GetParameters()["thinprovision"]
-	schld := req.GetParameters()["scheduler"]
-	fstype := req.GetParameters()["fstype"]
+
+	// parameter keys may be mistyped from the CRD specification when declaring
+	// the storageclass, which kubectl validation will not catch. Because ZFS
+	// parameter keys (not values!) are all lowercase, keys may safely be forced
+	// to the lower case.
+	originalParams := req.GetParameters()
+	parameters := helpers.GetCaseInsensitiveMap(&originalParams)
+
+	rs := parameters["recordsize"]
+	bs := parameters["volblocksize"]
+	compression := parameters["compression"]
+	dedup := parameters["dedup"]
+	encr := parameters["encryption"]
+	kf := parameters["keyformat"]
+	kl := parameters["keylocation"]
+	pool := parameters["poolname"]
+	tp := parameters["thinprovision"]
+	schld := parameters["scheduler"]
+	fstype := parameters["fstype"]
 
 	vtype := zfs.GetVolumeType(fstype)
 
@@ -130,7 +139,9 @@ func CreateZFSVolume(req *csi.CreateVolumeRequest) (string, error) {
 func CreateZFSClone(req *csi.CreateVolumeRequest, snapshot string) (string, error) {
 
 	volName := req.GetName()
-	pool := req.GetParameters()["poolname"]
+	parameters := req.GetParameters()
+	// lower case keys, cf CreateZFSVolume()
+	pool := helpers.GetInsensitiveParameter(&parameters, "poolname")
 	size := req.GetCapacityRange().RequiredBytes
 	volsize := strconv.FormatInt(int64(size), 10)
 
@@ -188,7 +199,9 @@ func (cs *controller) CreateVolume(
 	var selected string
 
 	volName := req.GetName()
-	pool := req.GetParameters()["poolname"]
+	parameters := req.GetParameters()
+	// lower case keys, cf CreateZFSVolume()
+	pool := helpers.GetInsensitiveParameter(&parameters, "poolname")
 	size := req.GetCapacityRange().RequiredBytes
 	contentSource := req.GetVolumeContentSource()