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scgi-server.lua
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scgi-server.lua
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--[[
Implementaton Notes:
-- header.REQUEST_URI or header.SCRIPT_FILENAME etc aren't validated to be within
-- the DOCUMENT_ROOT, we make nginx check this for us with try_files $uri = 404;
-- validate_headers() is largely unnecessary since nginx also will send the
-- correct headers as per the SCGI spec every time
-- The only real checking we do is make sure that no duplicate headers are sent,
-- in that: We can either error or only accept the first value defined per the
-- duplicate header. (like the first CONTENT_LENGTH value)
]]
-- this is because of the 5.1 to 5.2 migration on Arch :(
package.path =
package.path ..
';/usr/lib/lua/?.lua;'
package.cpath =
package.cpath ..
';/usr/lib/lua/?.so;'
local posix = require('posix')
local socket = require('socket')
-- {{{ some helpers
table.shift =
function (self)
return table.remove(self, 1)
end
table.pusht =
function (self, t2)
local n = #self
for _, v in ipairs(t2) do
n = n + 1
self[n] = v
end
return self
end
table.map =
function (self, f, ...)
for k, v in pairs(self) do
f(v, k, self, ...)
end
end
local empty =
function (self)
return next(self) == nil
end
local indexOf =
function (t, v, gen)
for idx, val in (gen or pairs)(t) do
if val == v then
return idx
end
end
end
-- }}}
local host = 'localhost'
local port = 8888
local r = {} -- the read "set"
local w = {} -- the write "set"
local threads = setmetatable({}, { __mode = 'k' }) -- threads vanish as sockets "drop out"
-- ['/script/path/from/document/root.lua'] = { attrs = lfs.attributes(...), source = ..., bytecode = ... }
local cache = {}
scgi = { cache = cache, conns = 0, failed = 0, succeeded = 0 }
local validate_scgi =
function (headers)
if headers[1] ~= 'CONTENT_LENGTH' then
error('SCGI spec mandates CONTENT_LENGTH be the first header')
end
if headers.CONTENT_LENGTH == '' then
error('SCGI requires CONTENT_LENGTH have a value, even if "0"')
end
if headers.SCGI ~= '1' then
error('request from webserver must have "SCGI" header with value of "1"')
end
-- enforce base 10, we should never have CONTENT_LENGTH: 0xFF (lol)
if not tonumber(headers.CONTENT_LENGTH, 10) then
error('CONTENT_LENGTH\'s value is not a number')
end
end
local recvall =
function (c)
local tmp = {}
while true do
local err, partial = select(2, c:receive('*a'))
-- timeout is EAGAIN (in a sense)
if err ~= 'timeout' then
error(err)
end
if partial == '' then
-- nothing read, we're done
break
end
table.insert(tmp, partial)
end
return table.concat(tmp)
end
local croutine =
function (c)
local netstring = recvall(c) or error('connection established but nothing received')
table.remove(r, indexOf(r, c)) -- we don't immediately need write so I'm a bit unhappy about this
table.insert(w, c)
coroutine.yield()
local netsize, scgistart = string.match(netstring, '^(%d+):()')
if not netsize then
error('netstring size not found in SCGI request')
end
local head = string.sub(netstring, scgistart, scgistart + netsize)
local headers = {}
for k, v in string.gmatch(head, '(%Z+)%z(%Z*)%z') do
if headers[k] then
error('duplicate SCGI header encountered')
end
table.insert(headers, k) -- track ordering
headers[k] = v
end
coroutine.yield() -- we've been at this long enough
validate_scgi(headers)
headers[0] = head
local body = string.sub(netstring, scgistart + netsize + 1, headers.CONTENT_LENGTH) -- 1 for ';' at the end of the header section
local path = headers.PATH_TRANSLATED
local attrs = posix.stat(path)
-- local attrs = lfs.attributes(path)
local cached = cache[path]
--[[
if
not cached or
attrs.modification ~= cached.attrs.modification or
attrs.change ~= cached.attrs.change
then
]]
if
not cached or
attrs.mtime ~= cached.attrs.mtime or
attrs.ctime ~= cached.attrs.ctime
then
local tmp = assert(io.open(path, 'rb'))
local source = tmp:read('*a')
assert(tmp:close())
if string.sub(source, 1, 2) == '#!' then
source = string.sub(source, (string.find(source, '\n', 1, true)))
end
local bytecode = assert(loadstring(source, path))
cached = { path = path, attrs = attrs, source = source, bytecode = bytecode }
cache[path] = cached
end
coroutine.yield() -- take a break
scgi.self = cached
scgi.request = netstring
scgi.headers = headers
scgi.body = body
local response = {}
local tmp = coroutine.create(cached.bytecode)
while true do
local stat = { coroutine.resume(tmp) }
local ok = table.shift(stat)
if not ok then
error(stat[1])
end
table.pusht(response, stat)
if coroutine.status(tmp) == 'dead' then
break
end
end
coroutine.yield()
-- bring it all together
response = table.concat(response)
if response == '' then
response = 'Content-Type: text/plain\r\nStatus: 204 No Content\r\n\r\nSCGI request successful; no output'
end
local i = 1
local len = #response
while i <= len do
local sent, err = c:send(response, i)
if not sent and err ~= 'timeout' then
error(err)
end
i = sent + 1
coroutine.yield()
end
assert(c:shutdown())
table.remove(w, indexOf(w, c))
end
local sroutine =
function (s)
while true do
local c = assert(s:accept())
assert(c:settimeout(0))
threads[c] = assert(coroutine.create(croutine))
table.insert(r, c) -- insert the new client in the read set
coroutine.yield()
end
end
local serv = assert(socket.tcp())
assert(serv:bind(host, port))
assert(serv:listen())
print(('Listening on %s:%s ...'):format(serv:getsockname()))
assert(serv:settimeout(0)) -- so we can non-blockingly :accept()
threads[serv] = assert(coroutine.create(sroutine))
table.insert(r, serv)
while true do
local read, write = socket.select(r, w)
for _, set in ipairs({ read, write }) do
for _, s in ipairs(set) do
local ok, err = coroutine.resume(threads[s], s)
if ok then
scgi.succeeded = scgi.succeeded + 1
else
print(err)
pcall(function () s:send('Content-Type: text/plain\r\nStatus: 500 Internal Server Error\r\n\r\n' .. err) end)
if s == serv then
serv:shutdown()
os.exit(false)
end
for _, set in pairs({ r, w }) do -- it may be in either of these
local idx = indexOf(set, s)
if idx then
table.remove(set, idx)
end
end
ok, err = pcall(function () s:close() end)
if not ok then
print(err)
end
scgi.failed = scgi.failed + 1
end
scgi.conns = scgi.conns + 1
end
end
end