IRCClient: Add is_channel_prefix to check if string is a channel name

Author: https://github.com/bcoles
Commit: https://github.com/SerenityOS/serenity/commit/6bf47252dcb
Pull-request: https://github.com/SerenityOS/serenity/pull/1580
Reviewed-by: https://github.com/awesomekling

Applications/IRCClient/IRCClient.cpp

@@ -388,7 +388,7 @@ void IRCClient::handle_user_input_in_server(const String& input)
         return handle_user_command(input);
 }
 
-bool IRCClient::is_nick_prefix(char ch) const
+bool IRCClient::is_nick_prefix(char ch)
 {
     switch (ch) {
     case '@':
@@ -401,6 +401,18 @@ bool IRCClient::is_nick_prefix(char ch) const
     return false;
 }
 
+bool IRCClient::is_channel_prefix(char ch)
+{
+    switch (ch) {
+    case '&':
+    case '#':
+    case '+':
+    case '!':
+        return true;
+    }
+    return false;
+}
+
 static bool has_ctcp_payload(const StringView& string)
 {
     return string.length() >= 2 && string[0] == 0x01 && string[string.length() - 1] == 0x01;
@@ -742,9 +754,10 @@ void IRCClient::handle_user_command(const String& input)
     if (command == "/TOPIC") {
         if (parts.size() < 2)
             return;
+        if (parts[1].is_empty())
+            return;
 
-        // FIXME: channel name validation should be abstracted away into a validation function
-        if (parts[1].starts_with("&") || parts[1].starts_with("#") || parts[1].starts_with("+") || parts[1].starts_with("!")) {
+        if (is_channel_prefix(parts[1][0])) {
             if (parts.size() < 3)
                 return;
             auto channel = parts[1];
@@ -763,9 +776,10 @@ void IRCClient::handle_user_command(const String& input)
     if (command == "/KICK") {
         if (parts.size() < 2)
             return;
+        if (parts[1].is_empty())
+            return;
 
-        // FIXME: channel name validation should be abstracted away into a validation function
-        if (parts[1].starts_with("&") || parts[1].starts_with("#") || parts[1].starts_with("+") || parts[1].starts_with("!")) {
+        if (is_channel_prefix(parts[1][0])) {
             if (parts.size() < 3)
                 return;
             auto channel = parts[1];

Applications/IRCClient/IRCClient.h

@@ -60,7 +60,8 @@ public:
     void part_channel(const String&);
     void change_nick(const String&);
 
-    bool is_nick_prefix(char) const;
+    static bool is_nick_prefix(char);
+    static bool is_channel_prefix(char);
 
     IRCWindow* current_window() { return aid_get_active_window(); }
     const IRCWindow* current_window() const { return aid_get_active_window(); }