Make requests abortable, display an error page if aborted.

Set generous default document size limits.
Cache text files and directory listings, nuke everything else after it's
sent to the client.

xtrn/go-for/go-for.js

@@ -10,9 +10,16 @@ load('typeahead.js');
  * - Improve address input (brighter, autodelete) (typeahead.js)
  * - Improve highlight visibility
  * - Shift-Tab?  Would have to store escaped state in input loop (I think)
+ * - m to search for selector in page (typeahead autocomplete)
+ * - s to select character encoding?  Apparently some servers now do utf8.
+ * - t to toggle TLS (or perhaps have the user specify this with the address, or attempt to connect with TLS first and fall back)
+ * - . to display the source
  */
 
 const cache_ttl = 300; // seconds - make configgy
+const max_dir_size = 4096000;
+const max_file_size = 1073741824;
+const max_text_size = 4096000;
 const timeout = 30; // seconds - make configgyable
 
 const type_map = {
@@ -148,8 +155,8 @@ function go_fetch(host, port, selector, type, query) {
     const socket = new Socket();
     if (!socket.connect(host, port)) return null;
 
-    const fn = get_cache_fn(host, port, selector);
-    const f = new File(fn);
+    var fn = get_cache_fn(host, port, selector);
+    var f = new File(fn);
 
     set_status(format('Requesting %s:%s %s ...', host, port, selector));
     if (type != '7') {
@@ -157,31 +164,59 @@ function go_fetch(host, port, selector, type, query) {
     } else {
         socket.sendline(selector + '\t' + query);
     }
-    const dl_start = time();
+
     set_status(format('Downloading %s:%s %s ...', host, port, selector));
 
+    var line;
+    var fs = 0;
     if (type == '1' || type == '7') { // this is a gopher directory
-        var line;
+        var parsed;
         f.open('w');
-        while (time() - dl_start < timeout && !js.terminated && socket.is_connected && (line = socket.recvline()) != '.') {
-            if (line) f.writeln(JSON.stringify(parse_line(line)));
+        while (!js.terminated && !console.aborted && socket.is_connected && fs <= max_dir_size && (line = socket.recvline()) != '.') {
+            if (line) {
+                last_dl = time();
+                parsed = JSON.stringify(parse_line(line));
+                f.writeln(parsed);
+                fs += parsed.length;
+            }
         }
         f.close();
     } else if (type == '0' || type == '6') { // this is a text file
         f.open('w');
-        while (time() - dl_start < timeout && !js.terminated && socket.is_connected) {
-            f.writeln(socket.recvline());
+        while (!js.terminated && !console.aborted && socket.is_connected && fs <= max_text_size) {
+            line = socket.recvline();
+            f.writeln(line);
+            last_dl = time();
+            fs += line.length;
         }
         f.close();
     } else if (['4', '5', '9', 'g', 'I'].indexOf(type) >  -1) { // this is a binary file
         f.open('wb');
-        while (time() - dl_start < timeout && !js.terminated && socket.is_connected) {
+        while (!js.terminated && !console.aborted && socket.is_connected && fs <= max_file_size) {
             f.writeBin(socket.recvBin(1), 1);
+            last_dl = time();
+            fs++;
         }
         f.close();
     }
 
-    set_status(format('Downloaded %s:%s %s', host, port, selector));
+    if (console.aborted) {
+        console.aborted = false;
+        const msg = format('Aborted download of %s:%s %s.', host, port, selector);
+        f.remove();
+        fn = get_cache_fn(host, port, selector + '_error');
+        f = new File(fn);
+        f.open('w');
+        if (type == '1' || type == '7') {
+            f.writeln(JSON.stringify(parse_line('i' + msg + '\tnull\tnull\t0')));
+        } else {
+            f.writeln(msg);
+        }
+        f.close();
+        set_status(format('Download of %s:%s %s aborted', host, port, selector));
+    } else {
+        set_status(format('Downloaded %s:%s %s', host, port, selector));
+    }
 
     return fn;
 
@@ -203,7 +238,6 @@ function go_for(host, port, selector, type, skip_cache, query) {
     state.port = port;
     state.selector = selector;
     set_address();
-    set_status(format('%s %s:%s %s', type_map[type], host, port, selector));
     return fn;
 }
 
@@ -213,8 +247,12 @@ function go_history() {
     print_document(false);
     if (loc.type != '1' && loc.type != '7') return;
     lowlight(state.doc[state.item], state.item);
-    state.item = loc.item;
-    state.history[state.history_idx].item = loc.item;
+    if (loc.item < 0) {
+        next_link();
+    } else {
+        state.item = loc.item;
+        state.history[state.history_idx].item = loc.item;
+    }
     highlight(state.doc[state.item], state.item);
     scrollbox.scroll_into_view(state.item);
 }
@@ -340,6 +378,7 @@ function print_document(auto_highlight) {
     } else if (['4', '5', '9', 'g', 'I'].indexOf(state.item_type) > -1) {
         console.clear(BG_BLACK|LIGHTGRAY);
         bbs.send_file(state.fn);
+        file_remove(state.fn);
         reset_display();
         go_back();
     }
@@ -374,8 +413,13 @@ function main() {
                 break;
             // Select current item
             case '\r':
-                if ((state.item_type == '1' || state.item_type == '7') && ['0', '1', '4', '5', '6', '9', 'g', 'I'].indexOf(state.doc[state.item].type) > -1) {
+                // Fetch a potentially-cached text file or directory listing
+                if ((state.item_type == '1' || state.item_type == '7') && ['0', '1', '6'].indexOf(state.doc[state.item].type) > -1) {
                     go_get(state.doc[state.item].host, state.doc[state.item].port, state.doc[state.item].selector, state.doc[state.item].type);
+                // Fetch a downloadable type, don't bother checking the cache
+                } else if ((state.item_type == '1' || state.item_type == '7') && ['4', '5', '9', 'g', 'I'].indexOf(state.doc[state.item].type) > -1) {
+                    go_get(state.doc[state.item].host, state.doc[state.item].port, state.doc[state.item].selector, state.doc[state.item].type, false, true);
+                // Prompt for a query and then submit it to this index-search selector
                 } else if (state.item_type == '1' && state.doc[state.item].type == '7') {
                     var query = get_query();
                     if (query && query.length) {