• Table of contents
• lighttpd request manipulation using Lua
  • Overview
  • Requirements
  • Options
  • Return Codes
  • Detecting Request Stage
  • Examples
  • Library Functions
  • mod_magnet API since lighttpd 1.4.60
    • lighty.r request object
    • lighty.server object (experimental)
    • lighty.c.* library functions (experimental)
  • lighttpd.conf configuration condition equivalents
• Deprecated
  • mod_magnet API before lighttpd 1.4.60
    • lighty.* tables
  • Porting mod_cml scripts

lighttpd request manipulation using Lua¶

Module: mod_magnet

Overview¶

mod_magnet enables programmatic manipulation of lighttpd request handling via Lua (programming language) scripts.

mod_magnet lua examples demonstrate the power and flexibility of a few lines of Lua with lighttpd. mod_magnet allows you to do more complex URL rewrites and caching than you might otherwise be able to do in lighttpd.conf, including .htaccess-like functionality in lighttpd.

While Lua is a very powerful programming language, learning basic string manipulation and plugging a lua script into lighttpd should be relatively straightforward for anyone with basic scripting experience in another scripting language (Python, PHP, Ruby, etc). Please review the lua examples here and give it a try! Questions? Post in the lighttpd Forums

Please note: mod_magnet is aimed at request manipulation such as url-rewriting and is not meant to be a general replacement for your entire scripting environment. mod_magnet executes lua scripts in the lighttpd core which makes lua scripting very fast in lighttpd, but any blocking operation (e.g. I/O to an external database) will pause the lighttpd server for all other requests. For time-consuming or blocking lua scripts, please run your script outside of lighttpd, using mod_fastcgi, mod_proxy, or other dynamic backend. For those interested in running time-consuming or blocking lua scripts, one option is a third-party FastCGI daemon such as luafcgid

Requirements¶

lighttpd 1.4.12 or higher built --with-lua
lua >= 5.1

Options¶

mod_magnet can attract a request during one or more stages of request handling. You may define multiple scripts, separated by commas, for each stage. The scripts are executed in the order specified. If a script returns a value other than 0 or 1xx, the scripts following will not be executed. See Return Codes below. For performance reasons, mod_magnet caches each compiled script. For each request, the script is checked and if the script has been modified, then the script is reloaded and recompiled. Script changes take effect upon the next request, without needing to restart lighttpd.

magnet.attract-raw-url-to = (...) - URL processing after HTTP request headers are received (and after mod_rewrite)
magnet.attract-physical-path-to = (...) - filesystem processing after document root and physical path are set to initial values
magnet.attract-response-start-to = (...) - response start after HTTP status is set and before response headers are finalized (since 1.4.56)

e.g. magnet.attract-physical-path-to = ( "/absolute/path/to/script.lua" )

Return Codes¶

• If script return 0, or returns nothing (or nil), request handling continues.
• If script return lighty.RESTART_REQUEST (currently equal to 99), the request is restarted, reprocessing the request-uri. This is usually used in combination with changing the ["request.uri"] attribute in a rewrite.
• If script returns 1xx, a 1xx intermediate response is sent, and request handling continues.
• If script returns >= 200, the value is used as final HTTP status code and the response is finalized. No other modules are executed.

Example redirecting "http" to "https": (lighty.* accessors are described further below)
(e.g. How to redirect HTTP requests to HTTPS using mod_redirect)

  local r = lighty.r
  local req_attr = r.req_attr
  if (req_attr["uri.scheme"] == "http") then
    r.resp_header["Location"] = "https://" .. req_attr["uri.authority"] .. req_attr["request.uri"]
    return 308
  end

Detecting Request Stage¶

If the same lua script is configured to run during multiple request stages, the lua script can detect the request stage using lighty.* (lighty.* accessors are described further below)

magnet.attract-raw-url-to

• lighty.r.req_attr["physical.path"] == nil
• (since lighttpd 1.4.65) lighty.r.req_item.http_status == 0
• (before lighttpd 1.4.65) lighty.r.req_attr["response.http-status"] == "0"

magnet.attract-physical-path-to

• lighty.r.req_attr["physical.path"] ~= nil
• (since lighttpd 1.4.65) lighty.r.req_item.http_status == 0
• (before lighttpd 1.4.65) lighty.r.req_attr["response.http-status"] == "0"

magnet.attract-response-start-to (since 1.4.56)

• (since lighttpd 1.4.65) lighty.r.req_item.http_status > 0
• (before lighttpd 1.4.65) lighty.r.req_attr["response.http-status"] > 0

Examples¶

 

• lua examples of lighttpd modules

• lua trigger functions

• Abso lua tion for additional info, code-snippets, examples ...

 

Library Functions¶

mod_magnet exports a few additional functions to the script:

• pairs() - extends the default pairs() function (for lua 5.1)
• print() - writes to the lighttpd error log; useful for debugging
  • e.g. print("Host: " .. lighty.r.req_header["Host"])
  • e.g. print("Request-URI: " .. lighty.r.req_attr["request.uri"])
• lighty.stat() - stat() file information (prefer: lighty.c.stat())

 

mod_magnet API since lighttpd 1.4.60¶

(The earlier mod_magnet API (above) is still supported, but the newer mod_magnet API (below) should be preferred.)

lighty.r request object¶

(since lighttpd 1.4.60)

lighty.r	description
lighty.r.req_header[]	HTTP request headers
lighty.r.req_attr[]	HTTP request attributes / components
lighty.r.req_item[]	HTTP request select internal members (since 1.4.65)
lighty.r.req_env[]	HTTP request environment variables
lighty.r.req_body.*	HTTP request body attributes and accessors (since 1.4.65)
lighty.r.resp_header[]	HTTP response headers
lighty.r.resp_body.*	HTTP response body attributes and accessors

lighty.r request object modification¶

• lighty.r.req_header[] allows get/set of request headers
  If modifications would affect config processing, script should return
  lighty.RESTART_REQUEST to have lighttpd restart the modified request.
  lighty.r.req_header[] differs from the older API lighty.env[] table,
  which (previously) did not permit modification of request headers.
  Note: header policy is not applied to values set in lighty.r.req_header[];
  Do not set unvalidated, untrusted, or non-normalized values.
  Note: if iterating using pairs(), do not set request header to blank value
  during iteration, or else iteration may end up skipping request headers.

• lighty.r.req_attr[] allows get/set of request attributes and is detailed further below.
  lighty.r.req_attr[] is the same as the (less clearly named) older API lighty.env[]

• lighty.r.req_item[] allows (mostly) read-only access to select internal request members
  and is detailed further below. (since 1.4.65)

• lighty.r.req_env[] allows get/set of request environment variables
  lighty.r.req_env[] is the same as the older API lighty.req_env[]
  Note: modifications made to standard CGI environment variables
  will be overwritten by backends recreating the CGI environment.
  However, new variables will persist into the env passed to backend scripts.

• lighty.r.req_body.* adds/sets request body content (since 1.4.65)

  lighty.r.req_body	description
  lighty.r.req_body.len	HTTP request body length (0 if none; -1 if not yet known; >= 0 if Content-Length sent by client or request body complete)
  lighty.r.req_body.collect	HTTP request body schedule collection (after which request will be restarted and scripts re-run) (note: request body offload disables request streaming to backend; defers connecting to backend) - returns 1 if request body complete (and then script can call r.req_body.get) - returns 0 if request body incomplete (and then script should return 0 so script can be re-run later)
  lighty.r.req_body.get	HTTP request body get (NB: reads entire request into memory; check r.req_body.len for sanity) (nil if request body incomplete (see r.req_body.collect))
  lighty.r.req_body.add()	HTTP request body add (string or table of strings) (should also r.req_header["Content-Length"] = nil (or set to actual value) if used)
  lighty.r.req_body.set()	HTTP request body set (string or table of strings) (should also r.req_header["Content-Length"] = nil (or set to actual value) if used)
  lighty.r.req_body.bytes_in	HTTP request body bytes received from client (reset by r.req_body.set())
  lighty.r.req_body.bytes_out	HTTP request body bytes sent to backend (reset by r.req_body.set())

• lighty.r.resp_header[] allows get/set of response headers
  (Certain connection-level headers such as Connection and
  Transfer-Encoding are restricted from modification)
  lighty.r.resp_headers[] differs from the older API lighty.header[] table,
  which is collected and deferred, being applied after the script exits.
  Note: header policy is not applied to values set in lighty.r.resp_header[];
  Do not set unvalidated, untrusted, or non-normalized values.
  To repeated header names, such as Set-Cookie or Link, join with "\r\nNAME:"
  lighty.r.resp_header["Link"] = "http://a.com/a.css\r\nLink: http:/b.com/b.js"

• lighty.r.resp_body.* adds/sets response body content
  lighty.r.resp_body.* differs from the older API lighty.content[] table,
  which is collected and deferred, being applied after the script exits.

  lighty.r.resp_body	description
  lighty.r.resp_body.len	HTTP response body length
  lighty.r.resp_body.get	HTTP response body get (NB: reads entire response into memory; check r.resp_body.len for sanity) (since 1.4.65)
  lighty.r.resp_body.add()	HTTP response body add (string or table)
  lighty.r.resp_body.set()	HTTP response body set (string or table)
  lighty.r.resp_body.bytes_in	HTTP response body bytes queued to send (since 1.4.65)
  lighty.r.resp_body.bytes_out	HTTP response body bytes sent to client (since 1.4.65)

-- examples
local r = lighty.r
local resp_header = r.resp_header
resp_header["Content-Type"] = "text/html" 
resp_header["Cache-Control"] = "max-age=0" 
r.resp_body:set({'bar\n'})  -- equivalent to below 'set'
-- (suggested if script run via magnet.attract-response-start-to)
resp_header["Content-Length"] = nil
-- alternatives
r.resp_body.set({'bar\n'})  -- equivalent to above 'set'
lighty.r.resp_header["Content-Type"] = "text/html" 
-- deprecated older syntax (API before lighttpd 1.4.60) (less clearly named)
lighty.header["Content-Type"] = "text/html" 
lighty.content = {'bar\n'}

lighty.r.req_attr[] readable attributes¶

lighty.r.req_attr[]	description
["uri.scheme"]	("http", "https")
["uri.authority"]	URI authority or Host request header
["uri.path"]	url-path without the query-string; url-path is url-decoded
["uri.path-raw"]	url-path without the query-string; url-path is not url-decoded (url-path component from ["request.uri"], i.e. without query-string)
["uri.query"]	query-string; URL part following '?'; query-string is not url-decoded
["request.method"]	request method (e.g. GET)
["request.protocol"]	request protocol ("HTTP/1.0", "HTTP/1.1", "HTTP/2.0")
["request.uri"]	URI after mod_rewrite rules, if any, else same as request.orig-uri
["request.orig-uri"]	URI before mod_rewrite; original request-uri sent by client
["request.path-info"]	path-info following url-path
["request.server-addr"]	server addr
["request.server-port"]	server port
["request.remote-addr"]	remote addr
["request.remote-port"]	remote port
["request.server-name"]	often the same as ["uri.authority"] unless server.name configured in lighttpd.conf
["request.stage"]	string tag of internal request stage (e.g. for dislay; similar to mod_status)
["physical.doc-root"]	filesystem document root (original)
["physical.basedir"]	filesystem document root (same as physical.doc-root unless adjusted by mod_alias, mod_userdir, ...)
["physical.path"]	filesystem path to request (beginning with physical.basedir)
["physical.rel-path"]	filesystem path to request (piece appended to physical.basedir)
["response.http-status"]	HTTP response status (0 if not yet set) (DEPRECATED; replace with lighty.r.req_item.http_status since lighttpd 1.4.65) (REMOVED in lighttpd 1.4.68)
["response.body-length"]	HTTP response body length (DEPRECATED; replace with lighty.r.resp_body.len since lighttpd 1.4.60) (REMOVED in lighttpd 1.4.68) (nil unless response body is complete)
["response.body"]	HTTP response body (DEPRECATED; replace with lighty.r.resp_body.get since lighttpd 1.4.65) (REMOVED in lighttpd 1.4.68) (nil unless response body is complete) (copies response in memory; should not be used on very large responses)

A full URI can be reconstructed using components:

local req_attr = lighty.r.req_attr
local query_string = req_attr["uri.query"]
local url = req_attr["uri.scheme"]
         .. "://" 
         .. req_attr["uri.authority"]
         .. req_attr["uri.path-raw"]
         .. (query_string and ("?" .. query_string) or "")

More examples:

-- curl "https://example.org/search.php?q=lighty" 
-- results in a request like:
--   GET /search.php?q=lighty HTTP/1.1
--   Host: example.org

local r = lighty.r
local req_attr = r.req_attr
local req_header = r.req_header

-- scripts run via magnet.attract-raw-url-to can access the following variables:

-- parts of the request-line
req_attr["request.uri"] == "/search.php?q=lighty" 
-- HTTP request-headers
req_header["Host"] == "example.org" 
-- parts of the URI
req_attr["uri.path"] == "/search.php" 
req_attr["uri.path-raw"] == "/search.php" 
req_attr["uri.scheme"] == "https" 
req_attr["uri.authority"] == "example.org" 
req_attr["uri.query"] == "q=lighty" 

-- Later in the request-handling, the URL is split, cleaned up, and turned into a physical path name
-- scripts run via magnet.attract-physical-path-to can access the following variables:

-- filenames, pathnames
req_attr["physical.path"] == "/my-docroot/search.php" 
req_attr["physical.rel-path"] == "/search.php" 
req_attr["physical.doc-root"] == "/my-docroot" 
req_attr["physical.basedir"] == "/my-docroot"  -- same as doc-root unless changed, e.g. by mod_alias

-- All of them are readable, but not all of them are writable (or have no effect if you write to them).  Some examples writing changes:

-- change physical-path
req_attr["physical.path"] = ...

-- change query-string
req_attr["uri.query"] = ...

-- simple rewrite
req_attr["request.uri"] = ...
return lighty.RESTART_REQUEST

Some lighty.r.req_attr[] attributes provide similar values to those in the standard CGI/1.1 environment

lighty.r.req_attr[]	CGI/1.1 env var
["uri.scheme"]	REQUEST_SCHEME
["uri.authority"]	SERVER_NAME
["uri.path"]	SCRIPT_NAME
["uri.query"]	QUERY_STRING
["request.method"]	REQUEST_METHOD
["request.protocol"]	SERVER_PROTOCOL
["request.path-info"]	PATH_INFO
["request.remote-addr"]	REMOTE_ADDR
["request.remote-port"]	REMOTE_PORT
["request.server-addr"]	SERVER_ADDR
["request.server-port"]	SERVER_PORT
["request.server-name"]	SERVER_NAME
["physical.doc-root"]	DOCUMENT_ROOT
["physical.basedir"]	DOCUMENT_ROOT
["physical.path"]	SCRIPT_FILENAME
["physical.rel-path"]	SCRIPT_NAME

lighty.r.req_attr[] writable attributes¶

Modifications to specific attributes or components are fairly direct interfaces
into lighttpd internals and do not affect other related attributes, including
the full request from which the attributes or component may have been derived.

What does this mean?
It means: carefully test your scripts and verify desired behavior.

If full request reprocessing is needed after any modification,
e.g. if modifications would affect config processing, script should
return lighty.RESTART_REQUEST

lighty.r.req_attr[]	description
["uri.scheme"]	modification has similar effect as changing scheme in mod_extforward If reprocessing request is needed, then return lighty.RESTART_REQUEST
["uri.authority"]	modification should generally be repeated to lighty.r.req_header["Host"] If reprocessing request is needed, then return lighty.RESTART_REQUEST
["uri.path"]	modification discouraged; derived from ["request.uri"], url-decoded and path-simplified; prefer to modify ["request.uri"] and return lighty.RESTART_REQUEST
["uri.query"]	modification affects subsequent use of query-string by other modules If reprocessing request is needed, prefer to modify ["request.uri"] and return lighty.RESTART_REQUEST
["request.uri"]	modification has similar effect as using mod_rewrite and should be followed by return lighty.RESTART_REQUEST so that lighttpd reprocesses the request and reparses the URI into components. "request.uri" can be reconstructed using components: ["request.uri"] = ["uri.path-raw"] "?" ["uri.query"]
["request.orig-uri"]	modification discouraged
["request.path-info"]	modification affects subsequent use of path-info by other modules If reprocessing request is needed, prefer to modify ["request.uri"] and return lighty.RESTART_REQUEST
["request.remote-addr"]	modification changes remote_addr for all subsequent requests on connection modification has similar effect as using mod_extforward (though mod_extforward additionally updates forwarding headers) If reprocessing request is needed, then return lighty.RESTART_REQUEST
["request.remote-port"]	modification changes remote_addr port for all subsequent requests on connection
["physical.doc-root"]	modification affects subsequent use of the doc_root by other modules (e.g. mod_ssi mod_webdav (limited use as fallback))
["physical.basedir"]	modification affects subsequent use of the basedir by other modules (e.g. as DOCUMENT_ROOT passed to backend scripts, unless modified elsewhere)
["physical.path"]	modification affects subsequent use of the path by other modules (e.g. mod_staticfile and many other filesystem based modules) modification has similar effect as using mod_alias (when script called from magnet.attract-physical-path-to hook)
["physical.rel-path"]	modification affects subsequent use of the relative path by other modules (e.g. mod_ssi mod_userdir mod_webdav)

["physical.*"] attributes are valid for scripts called from magnet.attract-physical-path-to hook. The attributes are not defined in earlier magnet hooks, and have almost no effect in later magnet hooks.

lighty.r.req_item[] readable attributes (since 1.4.65)¶

• req_item provides raw read-only access to select lighttpd internal request members
• req_item values are generally integers; req_attr values are generally strings
• req_item is not iterable; req_attr is iterable with pairs()
• Depending the magnet hook in which the lua script is run,
  req_item values may not be set or may not be the final values.

lighty.r.req_item[]	(alternative)	description
["http_status"]	req_item.http_status	request HTTP status (0 if not yet set)
["req_header_len"]	req_item.req_header_len	request header length
["resp_header_len"]	req_item.resp_header_len	response header length (0 if not yet set)
["bytes_in"]	req_item.bytes_in	request bytes read
["bytes_out"]	req_item.bytes_out	request bytes sent
["stream_id"]	req_item.stream_id	HTTP/2 stream id
["start_time"]()	req_item.start_time()	request start time (secs, nsecs) (note: function requires parentheses ())
["req_count"]	req_item.req_count	requests started on connection (note: HTTP/2 streams can be started in parallel)
["keep_alive"]	req_item.keep_alive	request keep-alive state (1 keep-alive; 0 close (or HTTP/2); -1 close, goaway)

lighty.r.req_item[] writable attributes (since 1.4.65)¶

lighty.r.req_item[]	(alternative)	description
["keep_alive"]	req_item.keep_alive	request keep-alive state (settable to 0 or -1) (1 keep-alive; 0 close (or HTTP/2); -1 close, goaway)

.

lighty.server object (experimental)¶

(since lighttpd 1.4.65)

lighty.r	description
lighty.server.irequests()	iterate over client requests
lighty.server.plugin_stats[]	statistics for backend modules (equivalent to old API lighty.status)
lighty.server.stats[]	server statistics

lighty.server.irequests() (since 1.4.65)¶

• iterate over client requests
• Note: iterator object is reused each iteration
  (copy out desired leaf info before iterating; save only strings or numbers)
  (iterator object is not valid outside iteration loop; do not save iterator object)
• examples: lua mod_status, lua mod_evasive, lua mod_uploadprogress

lighty.server.plugin_stats[] (since 1.4.65)¶

• statistics for backend modules
  (equivalent to lighty.status)
  (similar to output from mod_status status.statistics-url)
• example: mod_magnet can add statistics to the mod_status global statistics page.
  • lighttpd.conf
    server.modules += ("mod_magnet", "mod_status")
status.statistics-url = "/server-counters"
magnet.attract-raw-url-to = (server.docroot + "/counter.lua")
  • counter.lua
    local plugin_stats = lighty.server.plugin_stats
plugin_stats["magnet.connections"] = plugin_stats["magnet.connections"] + 1
  • Result of accessing /server-counters
magnet.connections: 7
fastcgi.backend.php-foo.0...
fastcgi.backend.php-foo.1...
fastcgi.backend.php-foo.load: 0

lighty.server.stats[] (since 1.4.65)¶

lighty.server.stats[]	description
clients_open	number of open client connections
uptime	uptime (in seconds)
version	version string

.

lighty.c.* library functions (experimental)¶

(since lighttpd 1.4.60)

Note: the lighty.c.* namespace is EXPERIMENTAL / UNSTABLE
In the future, these may be removed, altered, or moved to a different namespace.

-- digests and passwords

lighty.c.time()             -- seconds since 1 Jan 1970 00:00:00 (cached; faster than os.time())
lighty.c.hrtime()           -- (seconds, nanoseconds) since 1 Jan 1970 00:00:00 (high resolution) (since 1.4.65)
lighty.c.rand()             -- generate pseudo-random number
lighty.c.md()               -- calculate message digest (md5,sha1,sha256,sha512)
lighty.c.hmac()             -- calculate HMAC           (md5,sha1,sha256,sha512)
lighty.c.digest_eq()        -- timing-safe comparison of two hex digests
lighty.c.secret_eq()        -- timing-safe comparison of two strings

-- decode/encode

lighty.c.b64urldec()        -- base64url decode (validate and decode)
lighty.c.b64urlenc()        -- base64url encode, no padding
lighty.c.b64dec()           -- base64 decode (validate and decode)
lighty.c.b64enc()           -- base64 encode, no padding
lighty.c.hexdec()           -- hex decode (validate and decode)
lighty.c.hexenc()           -- hex encode uc; lc w/ lua s = s:lower()
lighty.c.xmlenc()           -- xml-encode/html-encode: <>&'\"`
lighty.c.urldec()           -- url-decode
lighty.c.urlenc()           -- url-encode
lighty.c.urldec_query()     -- url-decode query-string into table (since 1.4.65)
lighty.c.urlenc_query()     -- url-encode query-string from table (since 1.4.65)
lighty.c.urlenc_normalize() -- url-encode normalization
lighty.c.fspath_simplify()  -- simplify fspath (remove "/." "/.." "/../" "//")
lighty.c.quoteddec()        -- decode MIME quoted-string (since 1.4.65)
lighty.c.quotedenc()        -- encode input as MIME quoted-string (since 1.4.65)
lighty.c.bsdec()            -- decode backspace-escaped string (since 1.4.65)
lighty.c.bsenc()            -- encode CTLs and non-ASCII input as hex (\xFF) backspace-escaped string (since 1.4.65)
lighty.c.bsenc_json()       -- encode CTLs and non-ASCII input as json (\uFFFF) backspace-escaped string (since 1.4.66)

-- misc

lighty.c.cookie_tokens()    -- parse HTTP Cookie header into table (since 1.4.65)
lighty.c.header_tokens()    -- parse HTTP header into sequence table (since 1.4.65)
lighty.c.readdir()          -- dir walk
lighty.c.stat()             -- stat() path

message digest (md) and hash-based message authentication code (HMAC)
(MD5, SHA1, SHA256, SHA512)¶

lighty.c.md("algo", "data")
lighty.c.hmac("algo", "secret", "data")

• "algo" can be one of: "md5", "sha1", "sha256", "sha512"
  (as long as lighttpd is compiled w/ crypto lib supporting those algorithms)
• returns uppercase hex string of digest

lighty.c.digest_eq("digest1", "digest2")

• performs a timing-safe, case-insensitive comparison of two hex digests
  (timing-safe comparison is slightly more secure than digest1 == digest2)
• "digest1" and "digest2" are hex strings (of binary digests)
• returns boolean true or false

lighty.c.secret_eq("data1", "data2")

• performs a timing-safe comparison of two strings
  (and attempts to hide differences in string lengths)
  (timing-safe comparison is slightly more secure than data1 == data2)
• "data1" and "data2" are strings
• returns boolean true or false

decode/encode¶

lighty.c.b64urldec("base64url-string")
lighty.c.b64urlenc("string")

• base64url decode/encode (without padding)
• RFC4648 base64url (URL- and filename-safe standard), not base64 (standard)
  https://en.wikipedia.org/wiki/Base64

lighty.c.b64dec("base64-string")
lighty.c.b64enc("string")

• base64 decode/encode (without padding)
• RFC4648 base64
  https://en.wikipedia.org/wiki/Base64

lighty.c.urldec_query("query-string") (since 1.4.65)
lighty.c.urlenc_query("query-string") (since 1.4.65)

• url-decode query-string into table or url-encode table into query-string
• table value for a decoded key is blank ("") if no '=' follows "key"
• table value for a decoded key is blank ("") if blank value follows "key="
• encoding results in "key=" if value is blank ("")

lighty.c.quoteddec("quoted-string") (since 1.4.65)
lighty.c.quotedenc("string") (since 1.4.65)

• quoteddec: decode input quoted-string
  (remove surrounding double-quotes, unescape quoted-pairs (string.gsub(str, '\\(["\\])?', '%1')))
  (simplistic convenience func; see lighty.c.bsdec for more thorough backslash-escape decoding)
• quotedenc: encode input as quoted-string
  (backslash-escape " and \ to quoted-pairs (string.gsub(str, '(["\\])', '\\%1')), then surround with double-quotes)
  (simplistic convenience func; see lighty.c.bsenc for more thorough backslash-escape encoding)

lighty.c.bsdec("escaped-string") (since 1.4.65)

• decode backspace-escaped string
  (decodes \", \\, \n (and other well-known CTL \-escapes), octal \000, hex \xFF, json \uFFFF) (json since 1.4.66)
  (removes double-quotes surrounding input, if present)

lighty.c.bsenc("string") (since 1.4.65)

• encode control chars or non-ASCII input as hex (\xFF) backspace-escaped string (or well-known CTL \-escapes, e.g. \n)
• double-quote (") and backslash (\) in input are also backslash-escaped
• result does not contain surrounding double-quotes; caller should add as appropriate

lighty.c.bsenc_json("string") (since 1.4.66)

• encode control chars or non-ASCII input as json (\uFFFF) backspace-escaped string (or well-known CTL \-escapes, e.g. \n)
• double-quote (") and backslash (\) in input are also backslash-escaped
• result does not contain surrounding double-quotes; caller should add as appropriate

misc¶

lighty.c.cookie_tokens("cookie-string") (since 1.4.65)

• parse HTTP Cookie header into table (Note: quoted-strings preserved as-is; not decoded)
• local cookies = lighty.c.cookie_tokens(lighty.r.req_header['Cookie'])
local identity = lighty.c.urldec(cookies["ident"])

lighty.c.header_tokens("header-string") (since 1.4.65)

• parse HTTP header into sequence table (Note: quoted-strings preserved as-is; not decoded)
• sequence table contains works/tokens and separators (, ; =) as separate elements
  (optional whitespace (OWS) and bad whitespace (BWS) is removed)
• local tokens = lighty.c.header_tokens(lighty.r.req_header['Accept-Encoding'])
• for i = 1, #tokens do tok = lighty.c.quoteddec(tokens[i]) ......... end
  In the case of Accept-Encoding, each encoding might optionally include ;q=0.x quality,
  which would be multiple elements in the tokens table (; q = 0.x)

lighty.c.readdir("/path/to/dir")

• dir walk
• skips "." or ".." for convenience
• local name
for name in lighty.c.readdir("/tmp") do r.resp_body:add({name, "\n"}) end

lighty.c.stat("/path")

• checks the existence of a file/dir/socket and returns the stat() information for it
• uses lighttpd internal stat-cache
• path: (string) absolute path
• returns: table with the following fields, or nil on error
  • is_file
  • is_dir
  • is_char
  • is_block
  • is_socket
  • is_link
  • is_fifo
  • st_mode
  • st_mtime
  • st_ctime
  • st_atime
  • st_uid
  • st_gid
  • st_size
  • st_ino
  • etag
  • content-type
  • http-response-send-file (similar to mod_staticfile) (since 1.4.64)
  • st_mtim() (returns secs, nsecs) (since 1.4.65)
  • st_ctim() (returns secs, nsecs) (since 1.4.65)
  • st_atim() (returns secs, nsecs) (since 1.4.65)

lighttpd.conf configuration condition equivalents¶

lighttpd.conf configuration condition mod_magnet lua equivalents

lighttpd.conf configuration condition	mod_magnet lua equivalent
$HTTP["request-method"]	lighty.r.req_attr["request.method"]
$HTTP["scheme"]	lighty.r.req_attr["uri.scheme"]
$HTTP["host"]	lighty.r.req_attr["uri.authority"]
$HTTP["url"]	lighty.r.req_attr["uri.path"] lighty.r.req_attr["uri.path-raw"]
$HTTP["querystring"]	lighty.r.req_attr["uri.query"]
$HTTP["remoteip"]	lighty.r.req_attr["request.remote-addr"] lighty.r.req_attr["request.remote-port"]
$SERVER["socket"]	lighty.r.req_attr["request.server-addr"] lighty.r.req_attr["request.server-port"]
$REQUEST_HEADER["..."]	lighty.r.req_header["..."]
$HTTP["cookie"]	lighty.r.req_header["Cookie"]
$HTTP["useragent"]	lighty.r.req_header["User-Agent"]
$HTTP["language"]	lighty.r.req_header["Accept-Language"]
$HTTP["referer"]	lighty.r.req_header["Referer"]

In mod_magnet stage magnet.attract-physical-path-to:

physical path	lighty.r.req_attr["physical.path"]
physical path exists	lighty.c.stat(...)

 

Deprecated¶

 

mod_magnet API before lighttpd 1.4.60¶

(Note: This old API is deprecated. Please prefer using the lighty.r request object)

lighty.* tables¶

Most of the interaction between mod_magnet and lighttpd is done through tables. Tables in lua are similar to hashes (Perl, Ruby), dictionaries (Java, Python), associative arrays (PHP), ... The following tables support pairs() to iterate over their entries.

• lighty.request[] - certain request headers like Host, Cookie, or User-Agent are available (prefer: lighty.r.req_header[])
• lighty.req_env[] - request environment variables (prefer: lighty.r.req_env[])
• lighty.env[] - request attributes (prefer: lighty.r.req_attr[]) (see lighty.r request object)
• lighty.header[] - certain response headers like Location are available (prefer: lighty.r.resp_header[])
• lighty.content[] - response body (prefer: lighty.r.resp_body.set())
• lighty.status[] - statistics (prefer: lighty.server.plugin_stats[])

lighty.header[] (prefer: lighty.r.resp_header[])¶

If you want to set a response header for your request, you can add a field to the lighty.header[] table:
lighty.header["Content-Type"] = "text/html"

lighty.content[] (prefer: lighty.r.resp_body.set())¶

You can generate your own content and send it as the response. The lighty.content[] table may contain strings, or tables of file info. After the script finishes, the response is generated as the result of concatenating all table elements in order.

• Strings - copied into response
• Tables - file info representing response
  • filename = "<absolute-path>" is required
  • offset = <number> [default: 0]
  • length = <number> [default: size of the file]
    This results in sending the range [offset, length-1] of the file.
    ('length' param is misnamed and actually indicates the range offset + 1; kept as such for historical compatibility with existing scripts)

lighty.content = { "<pre>", { filename = "/etc/motd" }, "</pre>" }
lighty.header["Content-Type"] = "text/html" 
return 200

Porting mod_cml scripts¶

mod_cml got replaced by mod_magnet.

• mod_cml functions memcache_get_string() memcache_get_long() memcache_exists() (and lighttpd.conf cml.memcache-hosts) should be replaced with a lua-only solution:
  https://github.com/silentbicycle/lua-memcached

• mod_cml function dir_files should be replaced with lighty.c.readdir() (since 1.4.60)

• CACHE_HIT in mod_cml:
  output_include = { "file1", "file2" }
return CACHE_HIT
  becomes in mod_magnet:
  lighty.r.resp_body.set({ { filename = "/path/to/file1" }, { filename = "/path/to/file2"} })
return 200

• CACHE_MISS in mod_cml:
  trigger_handler = "/index.php"
return CACHE_MISS
  becomes in mod_magnet:
  lighty.r.req_attr["request.uri"] = "/index.php"
return lighty.RESTART_REQUEST

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