Feature: Set tags via X-Tags message header

@see #119

utils/tools/message.go

@@ -1,4 +1,4 @@
-// Package tools provides various methods for variouws things
+// Package tools provides various methods for various things
 package tools
 
 import (
@@ -23,7 +23,7 @@ func RemoveMessageHeaders(msg []byte, headers []string) ([]byte, error) {
 	reBlank := regexp.MustCompile(`^\s+`)
 
 	for _, hdr := range headers {
-		// case-insentitive
+		// case-insensitive
 		reHdr := regexp.MustCompile(`(?i)^` + regexp.QuoteMeta(hdr+":"))
 
 		// header := []byte(hdr + ":")

utils/tools/tags.go

@@ -0,0 +1,25 @@
+package tools
+
+import (
+	"regexp"
+	"strings"
+)
+
+var (
+	// Invalid tag characters regex
+	tagsInvalidChars = regexp.MustCompile(`[^a-zA-Z0-9\-\ \_]`)
+
+	// Regex to catch multiple spaces
+	multiSpaceRe = regexp.MustCompile(`(\s+)`)
+)
+
+// CleanTag returns a clean tag, removing whitespace and invalid characters
+func CleanTag(s string) string {
+	s = strings.TrimSpace(
+		multiSpaceRe.ReplaceAllString(
+			tagsInvalidChars.ReplaceAllString(s, " "),
+			" ",
+		),
+	)
+	return s
+}