diff -r 6c7c50a4de32 -r bf8f2da84007 net/http/files.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/net/http/files.lua	Thu Nov 05 22:31:25 2020 +0100
@@ -0,0 +1,149 @@
+-- Prosody IM
+-- Copyright (C) 2008-2010 Matthew Wild
+-- Copyright (C) 2008-2010 Waqas Hussain
+--
+-- This project is MIT/X11 licensed. Please see the
+-- COPYING file in the source package for more information.
+--
+
+local server = require"net.http.server";
+local lfs = require "lfs";
+local new_cache = require "util.cache".new;
+local log = require "util.logger".init("net.http.files");
+
+local os_date = os.date;
+local open = io.open;
+local stat = lfs.attributes;
+local build_path = require"socket.url".build_path;
+local path_sep = package.config:sub(1,1);
+
+
+local forbidden_chars_pattern = "[/%z]";
+if package.config:sub(1,1) == "\\" then
+	forbidden_chars_pattern = "[/%z\001-\031\127\"*:<>?|]"
+end
+
+local urldecode = require "util.http".urldecode;
+local function sanitize_path(path) --> util.paths or util.http?
+	if not path then return end
+	local out = {};
+
+	local c = 0;
+	for component in path:gmatch("([^/]+)") do
+		component = urldecode(component);
+		if component:find(forbidden_chars_pattern) then
+			return nil;
+		elseif component == ".." then
+			if c <= 0 then
+				return nil;
+			end
+			out[c] = nil;
+			c = c - 1;
+		elseif component ~= "." then
+			c = c + 1;
+			out[c] = component;
+		end
+	end
+	if path:sub(-1,-1) == "/" then
+		out[c+1] = "";
+	end
+	return "/"..table.concat(out, "/");
+end
+
+local function serve(opts)
+	if type(opts) ~= "table" then -- assume path string
+		opts = { path = opts };
+	end
+	local mime_map = opts.mime_map or { html = "text/html" };
+	local cache = new_cache(opts.cache_size or 256);
+	local cache_max_file_size = tonumber(opts.cache_max_file_size) or 1024
+	-- luacheck: ignore 431
+	local base_path = opts.path;
+	local dir_indices = opts.index_files or { "index.html", "index.htm" };
+	local directory_index = opts.directory_index;
+	local function serve_file(event, path)
+		local request, response = event.request, event.response;
+		local sanitized_path = sanitize_path(path);
+		if path and not sanitized_path then
+			return 400;
+		end
+		path = sanitized_path;
+		local orig_path = sanitize_path(request.path);
+		local full_path = base_path .. (path or ""):gsub("/", path_sep);
+		local attr = stat(full_path:match("^.*[^\\/]")); -- Strip trailing path separator because Windows
+		if not attr then
+			return 404;
+		end
+
+		local request_headers, response_headers = request.headers, response.headers;
+
+		local last_modified = os_date('!%a, %d %b %Y %H:%M:%S GMT', attr.modification);
+		response_headers.last_modified = last_modified;
+
+		local etag = ('"%x-%x-%x"'):format(attr.change or 0, attr.size or 0, attr.modification or 0);
+		response_headers.etag = etag;
+
+		local if_none_match = request_headers.if_none_match
+		local if_modified_since = request_headers.if_modified_since;
+		if etag == if_none_match
+		or (not if_none_match and last_modified == if_modified_since) then
+			return 304;
+		end
+
+		local data = cache:get(orig_path);
+		if data and data.etag == etag then
+			response_headers.content_type = data.content_type;
+			data = data.data;
+			cache:set(orig_path, data);
+		elseif attr.mode == "directory" and path then
+			if full_path:sub(-1) ~= "/" then
+				local dir_path = { is_absolute = true, is_directory = true };
+				for dir in orig_path:gmatch("[^/]+") do dir_path[#dir_path+1]=dir; end
+				response_headers.location = build_path(dir_path);
+				return 301;
+			end
+			for i=1,#dir_indices do
+				if stat(full_path..dir_indices[i], "mode") == "file" then
+					return serve_file(event, path..dir_indices[i]);
+				end
+			end
+
+			if directory_index then
+				data = server._events.fire_event("directory-index", { path = request.path, full_path = full_path });
+			end
+			if not data then
+				return 403;
+			end
+			cache:set(orig_path, { data = data, content_type = mime_map.html; etag = etag; });
+			response_headers.content_type = mime_map.html;
+
+		else
+			local f, err = open(full_path, "rb");
+			if not f then
+				log("debug", "Could not open %s. Error was %s", full_path, err);
+				return 403;
+			end
+			local ext = full_path:match("%.([^./]+)$");
+			local content_type = ext and mime_map[ext];
+			response_headers.content_type = content_type;
+			if attr.size > cache_max_file_size then
+				response_headers.content_length = ("%d"):format(attr.size);
+				log("debug", "%d > cache_max_file_size", attr.size);
+				return response:send_file(f);
+			else
+				data = f:read("*a");
+				f:close();
+			end
+			cache:set(orig_path, { data = data; content_type = content_type; etag = etag });
+		end
+
+		return response:send(data);
+	end
+
+	return serve_file;
+end
+
+return {
+	serve = serve;
+}
+