Implemented auto TLS upgrade support

README.md

@@ -36,6 +36,7 @@ The following features are already (fully or partially) supported in BFG.
 * In-page text search
 * Ini-based customization of the current Ttk theme, content fonts and colors
 * Non-TLS mode for systems without TclTLS support
+* Automatic TLS upgrade support for Gopher and other protocols (configurable in the `bfg.ini` file)
 * Opening links in Torified windows (for the systems with torsocks installed)
 
 ## Non-supported features
@@ -117,7 +118,7 @@ You don't need to do any special combinations to open links in Tor once the pare
 BFG ships with a `bfg.ini` file that holds your configuration values and bookmarks.
 The main configuration sections are:
 
-* `[net]`: network-related configs, currently has "timeout" parameter and an optional "tls" parameter
+* `[net]`: network-related configs, currently has "timeout" parameter and an optional "tls" parameter (`auto` by default)
 * `[widget]`: general UI widget appearance (ttkTheme, font (button font), entryfont, statusfont)
 * `[style.general]`: general content area appearance (textfont, monofont\*, foreground color, background color)
 * `[style.link.normal]`: normal link colors (foreground, background)
@@ -184,7 +185,9 @@ The [Scroll protocol](gemini://scrollprotocol.us.to/) is essentially advertised
 
 ### Why does a Gopher-over-TLS (`gophers://` URL) resource still show plain `gopher://` links?
 
-Due to a purely technical limitation of the Gopher protocol (or rather the Gophermap format) itself, we cannot determine if a particular Gophermap entry points to a plain Gopher or a Gopher-over-TLS resource. Hence, only the links belonging to the same host/port pair that was already opened with a `gophers://` link are displayed as `gophers://` links. Everything else needs to be adjusted manually for now. Sorry for the inconvenience.
+Due to a purely technical limitation of the Gopher protocol (or rather the Gophermap format) itself, we cannot determine if a particular Gophermap entry points to a plain Gopher or a Gopher-over-TLS resource. Hence, only the links belonging to the same host/port pair that was already opened with a `gophers://` link are displayed as `gophers://` links.
+
+If the `tls` parameter in the `[net]` section of the `bfg.ini` file is set to `auto`, the client will try opening the TLS connection first regardless of the link type, so you don't have to worry about the URL scheme anymore..
 
 ### My system (or Tclkit) doesn't have TclTLS available, can I still use BFG for plaintext protocols?
 

bfg.ini

@@ -43,5 +43,5 @@ foreground=#111
 
 [net]
 timeout=5000
-tls=on
+tls=auto
 

bfg.tcl

@@ -111,12 +111,10 @@ if {$confini ne ""} {
 # load TLS support
 if {($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 {$bfg_tls_support eq 1} {
-  package require tls
-}
+} elseif {$bfg_tls_support eq "auto"} {
+  set bfg_tls_support 2
+} else {set bfg_tls_support 1}
+if {$bfg_tls_support ne 0} {package require tls}
 
 # generate fonts
 foreach fid {widget entry status text mono} {
@@ -157,11 +155,16 @@ proc trunc {s} {
 # 4) close the connection
 proc reqresp {host port reqline is_tls encoding} {
   global bfg_response bfg_net_timeout
+  set sock 0
   if {$is_tls eq 1} {
-    set sock [::tls::socket -autoservername true -async $host $port]
+    catch {set sock [::tls::socket -autoservername true -async $host $port]}
+  } elseif {$is_tls eq 2} {
+    catch {set sock [::tls::socket -autoservername true -async $host $port]}
+    if {$sock eq 0} {catch {set sock [socket -async $host $port]}}
   } else {
-    set sock [socket -async $host $port]
+    catch {set sock [socket -async $host $port]}
   }
+  if {$sock eq 0} {set bfg_response "Connection error"; return}
   global rcv_end_$sock
   unset -nocomplain rcv_end_$sock
   if {$encoding eq ""} {set encoding utf-8}
@@ -426,7 +429,7 @@ proc urldl {inputurl isbinary} {
         set bfg_response [string cat "3" $errmsg "\t-\t-\t-\r\n"]
       }
       return $scheme
-    } else {set is_tls 1}
+    } else {set is_tls $bfg_tls_support}
   }
   set encoding "utf-8"
   if {$isbinary eq 1} {set encoding "binary"}