Merge pull request #1520 from lightpanda-io/robots-fix-wikipedia

Fix how `robots.txt`handles utf8

src/browser/Robots.zig

@@ -121,7 +121,7 @@ fn freeRulesInList(allocator: std.mem.Allocator, rules: []const Rule) void {
 fn parseRulesWithUserAgent(
     allocator: std.mem.Allocator,
     user_agent: []const u8,
-    bytes: []const u8,
+    raw_bytes: []const u8,
 ) ![]const Rule {
     var rules: std.ArrayList(Rule) = .empty;
     defer rules.deinit(allocator);
@@ -131,6 +131,15 @@ fn parseRulesWithUserAgent(
 
     var state: State = .{ .entry = .not_in_entry, .has_rules = false };
 
+    // https://en.wikipedia.org/wiki/Byte_order_mark
+    const UTF8_BOM: []const u8 = &.{ 0xEF, 0xBB, 0xBF };
+
+    // Strip UTF8 BOM
+    const bytes = if (std.mem.startsWith(u8, raw_bytes, UTF8_BOM))
+        raw_bytes[3..]
+    else
+        raw_bytes;
+
     var iter = std.mem.splitScalar(u8, bytes, '\n');
     while (iter.next()) |line| {
         const trimmed = std.mem.trim(u8, line, &std.ascii.whitespace);
@@ -144,19 +153,16 @@ fn parseRulesWithUserAgent(
         else
             trimmed;
 
-        if (true_line.len == 0) {
-            continue;
-        }
+        if (true_line.len == 0) continue;
 
-        const colon_idx = std.mem.indexOfScalar(u8, true_line, ':') orelse return error.MissingColon;
+        const colon_idx = std.mem.indexOfScalar(u8, true_line, ':') orelse {
+            log.warn(.browser, "robots line missing colon", .{ .line = line });
+            continue;
+        };
         const key_str = try std.ascii.allocLowerString(allocator, true_line[0..colon_idx]);
         defer allocator.free(key_str);
 
-        const key = std.meta.stringToEnum(Key, key_str) orelse {
-            // log.warn(.browser, "robots key", .{ .key = key_str });
-            continue;
-        };
-
+        const key = std.meta.stringToEnum(Key, key_str) orelse continue;
         const value = std.mem.trim(u8, true_line[colon_idx + 1 ..], &std.ascii.whitespace);
 
         switch (key) {

src/http/Client.zig

@@ -375,19 +375,36 @@ fn robotsDoneCallback(ctx_ptr: *anyopaque) !void {
 
     var allowed = true;
 
-    if (ctx.status >= 200 and ctx.status < 400 and ctx.buffer.items.len > 0) {
-        const robots = try ctx.client.robot_store.robotsFromBytes(
-            ctx.client.config.http_headers.user_agent,
-            ctx.buffer.items,
-        );
+    switch (ctx.status) {
+        200 => {
+            if (ctx.buffer.items.len > 0) {
+                const robots: ?Robots = ctx.client.robot_store.robotsFromBytes(
+                    ctx.client.config.http_headers.user_agent,
+                    ctx.buffer.items,
+                ) catch blk: {
+                    log.warn(.browser, "failed to parse robots", .{ .robots_url = ctx.robots_url });
+                    // If we fail to parse, we just insert it as absent and ignore.
+                    try ctx.client.robot_store.putAbsent(ctx.robots_url);
+                    break :blk null;
+                };
 
-        try ctx.client.robot_store.put(ctx.robots_url, robots);
-
-        const path = URL.getPathname(ctx.req.url);
-        allowed = robots.isAllowed(path);
-    } else if (ctx.status == 404) {
-        log.debug(.http, "robots not found", .{ .url = ctx.robots_url });
-        try ctx.client.robot_store.putAbsent(ctx.robots_url);
+                if (robots) |r| {
+                    try ctx.client.robot_store.put(ctx.robots_url, r);
+                    const path = URL.getPathname(ctx.req.url);
+                    allowed = r.isAllowed(path);
+                }
+            }
+        },
+        404 => {
+            log.debug(.http, "robots not found", .{ .url = ctx.robots_url });
+            // If we get a 404, we just insert it as absent.
+            try ctx.client.robot_store.putAbsent(ctx.robots_url);
+        },
+        else => {
+            log.debug(.http, "unexpected status on robots", .{ .url = ctx.robots_url, .status = ctx.status });
+            // If we get an unexpected status, we just insert as absent.
+            try ctx.client.robot_store.putAbsent(ctx.robots_url);
+        },
     }
 
     var queued = ctx.client.pending_robots_queue.fetchRemove(