176 lines
4.3 KiB
Lua
Executable File
176 lines
4.3 KiB
Lua
Executable File
#!/usr/bin/lua
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--
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-- weatherstation.lua - a simple web server intended to be run from tcpd to
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-- expose sensors from the BeagleBone Weather cape and serve the web app.
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--
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-- List of files shared by this service.
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distfiles={}
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distfiles["/index.html"] = true
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distfiles["/style.css"] = true
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distfiles["/jquery.js"] = true
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distfiles["/processing.js"] = true
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distfiles["/spin.js"] = true
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distfiles["/weatherstation.js"] = true
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-- Base path for distfiles
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prefix="/usr/share/beaglebone/weather"
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-- Check that the filename is part of this demo.
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function filename_is_valid(filename)
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return distfiles[filename] ~= nil
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end
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-- Check if the string 's' starts with 'starting'
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function starts_with(s, starting)
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return string.sub(s, 1, string.len(starting)) == starting
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end
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-- Check if the string 's' ends with 'ending'
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function ends_with(s, ending)
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return string.sub(s, -string.len(ending)) == ending
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end
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-- Return the content type of the file based only on the file extension.
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function get_content_type(filename)
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if ends_with(filename, ".js") then
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return "application/javascript"
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elseif ends_with(filename, ".css") then
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return "text/css"
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elseif ends_with(filename, ".html") then
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return "text/html"
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elseif ends_with(filename, ".json") then
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return "application/json"
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else
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return "text/plain"
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end
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end
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-- Reads from STDIN until an empty or nil line is received.
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-- Returns the first line of the request.
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function read_request()
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local i = 0
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local lines = {}
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repeat
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local line = io.read("*line")
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if line == nil or line == "\r" then
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break
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end
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lines[i] = line
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i = i + 1
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until false
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return lines[0]
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end
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-- Return the entire contents of a file
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function read_file(filename)
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local f = io.open(filename, "rb")
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if f == nil then
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return nil
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end
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local content = f:read("*all")
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f:close()
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return content
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end
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-- Extract the value of the LABEL:VALUE pairs read from the device files.
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function extract_value(data, pat)
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local x = string.match(data, pat)
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if x == nil then
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return "0"
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end
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return x
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end
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-- Read the sensor values and generate json output
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function generate_json()
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local json = ""
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local tsl2550 = read_file("/dev/tsl2550b3s39")
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if tsl2550 == nil then
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return nil
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end
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local illuminance = extract_value(tsl2550, "ILLUMINANCE: (%d+)")
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local sht21 = read_file("/dev/sht21b3s40")
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if sht21 == nil then
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return nil
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end
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local temperature = extract_value(sht21, "TEMPERATURE: (%d+.%d+)")
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local humidity = extract_value(sht21, "HUMIDITY: (%d+.%d+)")
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local bmp085 = read_file("/dev/bmp085b3s77")
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if bmp085 == nil then
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return nil
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end
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local pressure = extract_value(bmp085, "PRESSURE: (%d+)")
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json = json .. "{\n"
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json = json .. "\"temperature\": " .. temperature .. ",\n"
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json = json .. "\"humidity\": " .. humidity .. ",\n"
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json = json .. "\"illuminance\": " .. illuminance .. ",\n"
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json = json .. "\"pressure\": " .. pressure .. "\n"
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json = json .. "}\n"
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return json
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end
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function handle_request(req)
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if req == nil then
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response("404 Not Found", "text/plain", "Unknown Request")
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return
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end
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-- Parse filename out of HTTP request
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local filename = (string.match(req, " %S+ "):gsub("^%s+", ""):gsub("%s+$", ""))
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if filename == "" or filename == "/" then
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filename = "/index.html"
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end
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-- Check if the filename is known (i.e. it's a file in the web app)
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if filename_is_valid(filename) then
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local contents = read_file(prefix .. filename)
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if contents ~= nil then
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response("200 OK", get_content_type(filename), contents)
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else
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response("404 Not Found", "text/plain", "Failed to load known file")
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end
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-- Else maybe the user is requesting the dynamic json data
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elseif starts_with(filename, "/weather.json") then
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local json = generate_json()
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if json == nil then
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response("500 Internal Server Error", "text/plain", "Could not get sensor values")
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else
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response("200 OK", get_content_type("/weather.json"), json)
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end
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-- Else, the user is requesting something not part of the app
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else
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response("403 Forbidden", "text/plain", "File not allowed.")
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end
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return
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end
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-- Send the response to the HTTP request.
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function response(err_code, content_type, content)
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io.write("HTTP/1.1 " .. err_code .. "\r\n")
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io.write("Content-Type: " .. content_type .. "\r\n")
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io.write("\r\n")
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io.write(content)
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io.write("\r\n")
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end
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-- Read the request and then handle it.
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handle_request(read_request())
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