[MM-24526] Filter * characters from the search terms in DB (#14884)

store/sqlstore/utils.go

@@ -7,6 +7,7 @@ import (
 	"database/sql"
 	"strconv"
 	"strings"
+	"unicode"
 
 	"github.com/mattermost/gorp"
 	"github.com/mattermost/mattermost-server/v5/mlog"
@@ -52,3 +53,38 @@ func finalizeTransaction(transaction *gorp.Transaction) {
 		mlog.Error("Failed to rollback transaction", mlog.Err(err))
 	}
 }
+
+// removeNonAlphaNumericUnquotedTerms removes all unquoted words that only contain
+// non-alphanumeric chars from given line
+func removeNonAlphaNumericUnquotedTerms(line, separator string) string {
+	words := strings.Split(line, separator)
+	filteredResult := make([]string, 0, len(words))
+
+	for _, w := range words {
+		if isQuotedWord(w) || containsAlphaNumericChar(w) {
+			filteredResult = append(filteredResult, strings.TrimSpace(w))
+		}
+	}
+	return strings.Join(filteredResult, separator)
+}
+
+// containsAlphaNumericChar returns true in case any letter or digit is present, false otherwise
+func containsAlphaNumericChar(s string) bool {
+	for _, r := range s {
+		if unicode.IsLetter(r) || unicode.IsDigit(r) {
+			return true
+		}
+	}
+	return false
+}
+
+// isQuotedWord return true if the input string is quoted, false otherwise. Ex :-
+// 		"quoted string"  -  will return true
+// 		unquoted string  -  will return false
+func isQuotedWord(s string) bool {
+	if len(s) < 2 {
+		return false
+	}
+
+	return s[0] == '"' && s[len(s)-1] == '"'
+}