Implemented an option to turn off TLS support

bfg.tcl

@@ -6,7 +6,6 @@
 # created by Luxferre in 2024, released into public domain
 
 package require uri
-package require tls
 package require inifile
 package require Tk
 
@@ -43,6 +42,7 @@ set bfg_highlight_fgcolor $bfg_main_fgcolor
 set bfg_highlight_bgcolor yellow
 set bfg_error_fgcolor red
 set bfg_error_bgcolor $bfg_main_bgcolor
+set bfg_tls_support 1
 
 # read configuration from ini
 set confini ""
@@ -52,6 +52,8 @@ set bookmarks ""
 if {$confini ne ""} {
   set val [::ini::value $confini net timeout $bfg_net_timeout]
   if {$val ne ""} {set bfg_net_timeout $val}
+  set val [::ini::value $confini net tls "on"]
+  if {$val ne ""} {set bfg_tls_support $val}
   set val [::ini::value $confini widget ttkTheme $bfg_theme]
   if {$val ne ""} {set bfg_theme $val}
   set val [::ini::value $confini widget font $bfg_widgetfont]
@@ -106,6 +108,16 @@ if {$confini ne ""} {
   ::ini::close $confini
 }
 
+# load TLS support
+if {($bfg_tls_support eq "off") || ($bfg_tls_support eq "false" || ($bfg_tls_support eq "none"))} {
+  set bfg_tls_support 0
+} else {
+  set bfg_tls_support 1
+}
+if {$bfg_tls_support eq 1} {
+  package require tls
+}
+
 # generate fonts
 foreach fid {widget entry status text mono} {
   set vname [string cat bfg_ $fid font]
@@ -392,6 +404,7 @@ proc extOpen {url} {
 # common URL downloader
 # return the contents in $bfg_response
 proc urldl {inputurl isbinary} {
+  global bfg_tls_support bfg_response
   set parts [url2dict $inputurl]
   set host [dict get $parts host]
   set port [dict get $parts port]
@@ -399,8 +412,18 @@ proc urldl {inputurl isbinary} {
   set selector [dict get $parts selector]
   set scheme [dict get $parts scheme]
   set is_tls 0
-  if {$scheme eq "gemini"} {set is_tls 1}
-  if {$scheme eq "gophers"} {set is_tls 1}
+  if {($scheme eq "gemini") || ($scheme eq "gophers")} {
+    if {$bfg_tls_support eq 0} { # report unsupported content
+      set errmsg {BFG error: TLS support is turned off in the configuration}
+      if {$scheme eq "gemini"} {
+        set bfg_response [string cat "50 " $errmsg "\r\n"]
+      }
+      if {$scheme eq "gophers"} {
+        set bfg_response [string cat "3" $errmsg "\t-\t-\t-\r\n"]
+      }
+      return $scheme
+    } else {set is_tls 1}
+  }
   set encoding "utf-8"
   if {$isbinary eq 1} {set encoding "binary"}
   reqresp $host $port $selector $is_tls $encoding