fix: hopefully better force self close tags setup

driver/netconf/driver.go

@@ -51,7 +51,7 @@ const (
 	// emptyTagPattern matches netconf empty tags to allow
 	// forcing of self-closing tags.
 	// See https://regex101.com/r/rmsS2E/3.
-	emptyTagPattern = `<([^>/]+?)(\s+[^>]+?)?>\s*</[\w-]+>`
+	emptyTagPattern = `<([^>/]+?)(\s+[^>]+?)?>\s*</([\w-]+)>`
 
 	defaultNamespace = "urn:ietf:params:xml:ns:yang:ietf-netconf-with-defaults"
 

driver/netconf/message.go

@@ -1,6 +1,7 @@
 package netconf
 
 import (
+	"bytes"
 	"encoding/xml"
 	"fmt"
 )
@@ -47,3 +48,52 @@ func (m *message) serialize(v string, forceSelfClosingTags bool) (*serializedInp
 
 	return serialized, nil
 }
+
+// ForceSelfClosingTags accepts a netconf looking xml byte slice and forces any "empty" tags (tags
+// without attributes) to use self-closing tags. For example:
+//
+// `<running> </running>`
+//
+// Would be converted to:
+//
+// `<running/>`.
+//
+// Ideally this functino would just be replaced with this: https://github.com/golang/go/issues/59710
+// but for now this is more preferred than having either a different regex library imported, or
+// importing @ECUST_XX proposed package. Historically, this was simply a regex.ReplaceAll but, there
+// are/were issues with the pattern accidentally matching over already self closed tags inside
+// other tags, for example:
+//
+// `<target><candidate xyz/></target>`
+//
+// Would end up like:
+//
+// `<target><candidate xyz//>
+//
+// Which is obviously not correct! This could be pretty easily solved in regex with backtracking/
+// capture groups but since we don't get that in std library go regex we can instead just write some
+// simple code to iterate over stuff and replace as needed after comparing the open/close tags that
+// our pattern found actually do match.
+func ForceSelfClosingTags(b []byte) []byte {
+	ncPatterns := getNetconfPatterns()
+
+	for _, sm := range ncPatterns.emptyTags.FindAllSubmatch(b, -1) {
+		fullMatch := sm[0]
+		openingTag := sm[1]
+		openingTagContents := sm[2]
+		closingTag := sm[3]
+
+		if !bytes.Equal(openingTag, closingTag) {
+			// we found a chunk that contains an already "self closed" tag, ignore this
+			continue
+		}
+
+		b = bytes.ReplaceAll(
+			b,
+			fullMatch,
+			[]byte(fmt.Sprintf("<%s%s/>", openingTag, openingTagContents)),
+		)
+	}
+
+	return b
+}

driver/netconf/rpc.go

@@ -26,19 +26,6 @@ func (d *Driver) RPC(opts ...util.Option) (*response.NetconfResponse, error) {
 	return d.sendRPC(d.buildRPCElem(op.Filter), op)
 }
 
-// ForceSelfClosingTags accepts a netconf looking xml byte slice and forces any "empty" tags (tags
-// without attributes) to use self-closing tags. For example:
-// `<running> </running>`
-// Would be converted to:
-// `<running/>`.
-func ForceSelfClosingTags(b []byte) []byte {
-	ncPatterns := getNetconfPatterns()
-
-	r := ncPatterns.emptyTags.ReplaceAll(b, []byte("<$1$2/>"))
-
-	return r
-}
-
 func (d *Driver) sendRPC(
 	m *message,
 	op *OperationOptions,

driver/netconf/rpc_test.go

@@ -39,6 +39,14 @@ func TestForceSelfClosingTags(t *testing.T) {
 			got:  []byte(`<running>  </running>`),
 			want: []byte(`<running/>`),
 		},
+		"dont_replace_already_self_closed_tags": {
+			got: []byte(
+				`<target><candidate xmlns="urn:nokia.com:sros:ns:yang:sr:ietf-netconf-augments"/></target>`, //nolint: lll
+			),
+			want: []byte(
+				`<target><candidate xmlns="urn:nokia.com:sros:ns:yang:sr:ietf-netconf-augments"/></target>`, //nolint: lll
+			),
+		},
 	}
 
 	for name, tt := range tests {