Supporting gzipped request body.

inflate_request_body.lua

-- lua-zlib is required

local MAX_BODY_SIZE = 16777216

ngx.ctx.max_chunk_size = tonumber(ngx.var.max_chunk_size) or 262144       -- 256KB
ngx.ctx.max_body_size = tonumber(ngx.var.max_body_size) or MAX_BODY_SIZE  -- 16MB

function bad_request_response(status, msg)
	local message = string.format('{"status": %d, "msg": "%s"}', status, msg)
	ngx.status = ngx.HTTP_BAD_REQUEST
	ngx.header.content_type = "application/json"
	ngx.say(message)
	ngx.exit(ngx.HTTP_OK)
end

function inflate_body(data)
	local stream = require("zlib").inflate()
	local buffer = ""
	local chunk = ""

	for index = 0, data:len(), ngx.ctx.max_chunk_size do
		chunk = string.sub(data, index, index + ngx.ctx.max_chunk_size - 1)
		local status, output, eof, bytes_in, bytes_out = pcall(stream, chunk)

		if not status then                        -- corrupted chunk
			ngx.log(ngx.ERR, output)
			bad_request_response(4003, "gzip格式已损坏")
		end

		if bytes_in == 0 and bytes_out == 0 then  -- body is not gzip compressed
			bad_request_response(4004, "非gzip压缩格式")
		end

		buffer = buffer .. output

		if bytes_out > ngx.ctx.max_body_size then -- uncompressed body too large
			bad_request_response(4005, "gzip解压结果太大")
		end
	end

	return buffer
end

local headers = ngx.req.get_headers()
local content_length = headers["Content-Length"]
local content_encoding = headers["Content-Encoding"]

if content_length and tonumber(content_length) > MAX_BODY_SIZE then
	bad_request_response(4005, "gzip解压结果太大")
end

if content_encoding and content_encoding:lower() == "gzip" then
	ngx.req.read_body()
	local data = ngx.req.get_body_data()

	if data == nil then
		local file_name = ngx.req.get_body_file()
		if file_name ~= nil and file_name ~= '' then
			local file = io.open(file_name, "r")
			data = file:read("*a")
			file:close()
		end
	end

	if data ~= nil and data ~= '' then
		if data:len() > MAX_BODY_SIZE then
			bad_request_response(4005, "gzip解压结果太大")
		end

		local new_data = inflate_body(data)
		ngx.req.clear_header("Content-Encoding")
		ngx.req.clear_header("Content-Length")
		ngx.req.set_body_data(new_data)
	end
end