luasocket/src/url.lua
2004-06-17 06:23:13 +00:00

267 lines
9.3 KiB
Lua

-----------------------------------------------------------------------------
-- URI parsing, composition and relative URL resolution
-- LuaSocket toolkit.
-- Author: Diego Nehab
-- RCS ID: $Id$
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
-- Encodes a string into its escaped hexadecimal representation
-- Input
-- s: binary string to be encoded
-- Returns
-- escaped representation of string binary
-----------------------------------------------------------------------------
function escape(s)
return string.gsub(s, "(.)", function(c)
return string.format("%%%02x", string.byte(c))
end)
end
-----------------------------------------------------------------------------
-- Protects a path segment, to prevent it from interfering with the
-- url parsing.
-- Input
-- s: binary string to be encoded
-- Returns
-- escaped representation of string binary
-----------------------------------------------------------------------------
local function make_set(t)
local s = {}
for i = 1, table.getn(t) do
s[t[i]] = 1
end
return s
end
-- these are allowed withing a path segment, along with alphanum
-- other characters must be escaped
local segment_set = make_set {
"-", "_", ".", "!", "~", "*", "'", "(",
")", ":", "@", "&", "=", "+", "$", ",",
}
local function protect_segment(s)
return string.gsub(s, "(%W)", function (c)
if segment_set[c] then return c
else return escape(c) end
end)
end
-----------------------------------------------------------------------------
-- Encodes a string into its escaped hexadecimal representation
-- Input
-- s: binary string to be encoded
-- Returns
-- escaped representation of string binary
-----------------------------------------------------------------------------
function unescape(s)
return string.gsub(s, "%%(%x%x)", function(hex)
return string.char(tonumber(hex, 16))
end)
end
-----------------------------------------------------------------------------
-- Builds a path from a base path and a relative path
-- Input
-- base_path
-- relative_path
-- Returns
-- corresponding absolute path
-----------------------------------------------------------------------------
local function absolute_path(base_path, relative_path)
if string.sub(relative_path, 1, 1) == "/" then return relative_path end
local path = string.gsub(base_path, "[^/]*$", "")
path = path .. relative_path
path = string.gsub(path, "([^/]*%./)", function (s)
if s ~= "./" then return s else return "" end
end)
path = string.gsub(path, "/%.$", "/")
local reduced
while reduced ~= path do
reduced = path
path = string.gsub(reduced, "([^/]*/%.%./)", function (s)
if s ~= "../../" then return "" else return s end
end)
end
path = string.gsub(reduced, "([^/]*/%.%.)$", function (s)
if s ~= "../.." then return "" else return s end
end)
return path
end
-----------------------------------------------------------------------------
-- Parses a url and returns a table with all its parts according to RFC 2396
-- The following grammar describes the names given to the URL parts
-- <url> ::= <scheme>://<authority>/<path>;<params>?<query>#<fragment>
-- <authority> ::= <userinfo>@<host>:<port>
-- <userinfo> ::= <user>[:<password>]
-- <path> :: = {<segment>/}<segment>
-- Input
-- url: uniform resource locator of request
-- default: table with default values for each field
-- Returns
-- table with the following fields, where RFC naming conventions have
-- been preserved:
-- scheme, authority, userinfo, user, password, host, port,
-- path, params, query, fragment
-- Obs:
-- the leading '/' in {/<path>} is considered part of <path>
-----------------------------------------------------------------------------
function parse(url, default)
-- initialize default parameters
local parsed = {}
for i,v in (default or parsed) do parsed[i] = v end
-- empty url is parsed to nil
if not url or url == "" then return nil, "invalid url" end
-- remove whitespace
-- url = string.gsub(url, "%s", "")
-- get fragment
url = string.gsub(url, "#(.*)$", function(f) parsed.fragment = f end)
-- get scheme
url = string.gsub(url, "^([%w][%w%+%-%.]*)%:",
function(s) parsed.scheme = s end)
-- get authority
url = string.gsub(url, "^//([^/]*)", function(n) parsed.authority = n end)
-- get query stringing
url = string.gsub(url, "%?(.*)", function(q) parsed.query = q end)
-- get params
url = string.gsub(url, "%;(.*)", function(p) parsed.params = p end)
-- path is whatever was left
if url ~= "" then parsed.path = url end
local authority = parsed.authority
if not authority then return parsed end
authority = string.gsub(authority,"^([^@]*)@",
function(u) parsed.userinfo = u end)
authority = string.gsub(authority, ":([^:]*)$",
function(p) parsed.port = p end)
if authority ~= "" then parsed.host = authority end
local userinfo = parsed.userinfo
if not userinfo then return parsed end
userinfo = string.gsub(userinfo, ":([^:]*)$",
function(p) parsed.password = p end)
parsed.user = userinfo
return parsed
end
-----------------------------------------------------------------------------
-- Rebuilds a parsed URL from its components.
-- Components are protected if any reserved or unallowed characters are found
-- Input
-- parsed: parsed URL, as returned by parse
-- Returns
-- a stringing with the corresponding URL
-----------------------------------------------------------------------------
function build(parsed)
local ppath = parse_path(parsed.path or "")
local url = build_path(ppath)
if parsed.params then url = url .. ";" .. parsed.params end
if parsed.query then url = url .. "?" .. parsed.query end
local authority = parsed.authority
if parsed.host then
authority = parsed.host
if parsed.port then authority = authority .. ":" .. parsed.port end
local userinfo = parsed.userinfo
if parsed.user then
userinfo = parsed.user
if parsed.password then
userinfo = userinfo .. ":" .. parsed.password
end
end
if userinfo then authority = userinfo .. "@" .. authority end
end
if authority then url = "//" .. authority .. url end
if parsed.scheme then url = parsed.scheme .. ":" .. url end
if parsed.fragment then url = url .. "#" .. parsed.fragment end
-- url = string.gsub(url, "%s", "")
return url
end
-----------------------------------------------------------------------------
-- Builds a absolute URL from a base and a relative URL according to RFC 2396
-- Input
-- base_url
-- relative_url
-- Returns
-- corresponding absolute url
-----------------------------------------------------------------------------
function absolute(base_url, relative_url)
local base = type(base_url) == "table" and base_url or parse(base_url)
local relative = parse(relative_url)
if not base then return relative_url
elseif not relative then return base_url
elseif relative.scheme then return relative_url
else
relative.scheme = base.scheme
if not relative.authority then
relative.authority = base.authority
if not relative.path then
relative.path = base.path
if not relative.params then
relative.params = base.params
if not relative.query then
relative.query = base.query
end
end
else
relative.path = absolute_path(base.path or "", relative.path)
end
end
return build(relative)
end
end
-----------------------------------------------------------------------------
-- Breaks a path into its segments, unescaping the segments
-- Input
-- path
-- Returns
-- segment: a table with one entry per segment
-----------------------------------------------------------------------------
function parse_path(path)
local parsed = {}
path = path or ""
--path = string.gsub(path, "%s", "")
string.gsub(path, "([^/]+)", function (s) table.insert(parsed, s) end)
for i = 1, table.getn(parsed) do
parsed[i] = unescape(parsed[i])
end
if string.sub(path, 1, 1) == "/" then parsed.is_absolute = 1 end
if string.sub(path, -1, -1) == "/" then parsed.is_directory = 1 end
return parsed
end
-----------------------------------------------------------------------------
-- Builds a path component from its segments, escaping protected characters.
-- Input
-- parsed: path segments
-- unsafe: if true, segments are not protected before path is built
-- Returns
-- path: corresponding path stringing
-----------------------------------------------------------------------------
function build_path(parsed, unsafe)
local path = ""
local n = table.getn(parsed)
if unsafe then
for i = 1, n-1 do
path = path .. parsed[i]
path = path .. "/"
end
if n > 0 then
path = path .. parsed[n]
if parsed.is_directory then path = path .. "/" end
end
else
for i = 1, n-1 do
path = path .. protect_segment(parsed[i])
path = path .. "/"
end
if n > 0 then
path = path .. protect_segment(parsed[n])
if parsed.is_directory then path = path .. "/" end
end
end
if parsed.is_absolute then path = "/" .. path end
return path
end