initial commit

.idea/.gitignore

@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/

.idea/iot-relay.iml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="WEB_MODULE" version="4">
+  <component name="Go" enabled="true" />
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

cmd/main.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	. "iot-relay/internal/client"
+	. "iot-relay/internal/config"
+	. "iot-relay/internal/server"
+	"log"
+)
+
+const configFile = "config.json"
+
+func main() {
+	log.Println("reading config file")
+	config, err := ReadConfig(configFile)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	log.Println("starting server")
+	err = Listen(config, GetHandler(config))
+	if err != nil {
+		log.Fatalln(err)
+	}
+}

config.json

@@ -0,0 +1,12 @@
+{
+  "server": {
+    "bind": "0.0.0.0:20159",
+    "timeout": 30
+  },
+  "client": {
+    "address": "http://localhost:8086",
+    "db": "grafana",
+    "measurement": "iot",
+    "host": "iot-relay"
+  }
+}

go.mod

@@ -0,0 +1,3 @@
+module iot-relay
+
+go 1.17

internal/client/client.go

@@ -0,0 +1,58 @@
+package client
+
+import (
+	"fmt"
+	"iot-relay/internal/config"
+	"iot-relay/internal/types"
+	"log"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func lineProtocol(request types.Request, config config.Config) string {
+	var builder strings.Builder
+	builder.WriteString(config.Client.Measurement)
+	builder.WriteString(",host=")
+	builder.WriteString(config.Client.Host)
+	builder.WriteString(",ip=")
+	builder.WriteString(request.IP)
+	builder.WriteString(",id=")
+	builder.WriteString(request.ID)
+	builder.WriteString(",loc=")
+	builder.WriteString(request.Location)
+	builder.WriteString(" ")
+
+	for key, value := range request.Data {
+		builder.WriteString(key)
+		builder.WriteString("=")
+		builder.WriteString(value)
+		builder.WriteString(" ")
+	}
+
+	builder.WriteString(strconv.FormatInt(time.Now().UnixNano(), 10))
+
+	return builder.String()
+}
+
+func GetHandler(config config.Config) types.Callback {
+	return func(request types.Request) error {
+		line := lineProtocol(request, config)
+
+		url := config.Client.Address + "/write?db=" + config.Client.DB
+
+		resp, err := http.Post(url, "application/octet-stream", strings.NewReader(line))
+		if err != nil {
+			log.Println(err)
+			return err
+		}
+		if resp.StatusCode != 204 {
+			err = fmt.Errorf("influxdb responded with %d", resp.StatusCode)
+			log.Println(err)
+			return err
+		}
+
+		return nil
+	}
+}

internal/config/config.go

@@ -0,0 +1,41 @@
+package config
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+)
+
+type Config struct {
+	Server struct {
+		Bind    string `json:"bind"`
+		Timeout int    `json:"timeout"` // in seconds
+	} `json:"server"`
+	Client struct {
+		Address     string `json:"address"`
+		DB          string `json:"db"`
+		Measurement string `json:"measurement"`
+		Host        string `json:"host"`
+	} `json:"client"`
+}
+
+func ReadConfig(filename string) (Config, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return Config{}, err
+	}
+
+	content, err := ioutil.ReadAll(file)
+	if err != nil {
+		return Config{}, err
+	}
+
+	var config Config
+
+	err = json.Unmarshal(content, &config)
+	if err != nil {
+		return Config{}, err
+	}
+
+	return config, nil
+}

internal/server/connection.go

@@ -0,0 +1,57 @@
+package server
+
+import (
+	"bufio"
+	"iot-relay/internal/types"
+	"log"
+	"net"
+	"strings"
+)
+
+func connectionHandler(conn net.Conn) {
+	reader := bufio.NewReader(conn)
+
+	defer func() {
+		log.Println("closing connection")
+		_ = conn.Close()
+	}()
+
+	var request types.Request
+	request.Data = make(map[string]string)
+	request.IP = strings.Split(conn.RemoteAddr().String(), ":")[0]
+
+	for {
+		line, err := reader.ReadString('\n')
+
+		if err != nil {
+			log.Printf("connection error: %v", err)
+			break
+		}
+
+		if len(line) == 1 {
+			// end of request
+
+			if !request.IsValid() {
+				log.Println("protocol error")
+				_, _ = conn.Write([]byte("bad\n"))
+				break
+			}
+
+			err = callback(request)
+			if err != nil {
+				// should be logged by callback
+				_, _ = conn.Write([]byte("fail\n"))
+			} else {
+				_, _ = conn.Write([]byte("ok\n"))
+			}
+			break
+		} else {
+			err = parseLine(line, &request)
+			if err != nil {
+				log.Printf("parsing error: %v", err)
+				_, _ = conn.Write([]byte("bad\n"))
+				break
+			}
+		}
+	}
+}

internal/server/parser.go

@@ -0,0 +1,38 @@
+package server
+
+import (
+	"errors"
+	"iot-relay/internal/types"
+	"strings"
+)
+
+var forbiddenKeys = []string{
+	"ip",
+}
+
+func parseLine(line string, request *types.Request) error {
+	token := strings.Split(line, "=")
+	if len(token) != 2 {
+		return errors.New("malformed; missing =")
+	}
+
+	key := strings.ToLower(token[0])
+	value := strings.TrimRight(token[1], "\n")
+
+	for _, forbidden := range forbiddenKeys {
+		if forbidden == key {
+			return errors.New("forbidden key")
+		}
+	}
+
+	switch key {
+	case "id":
+		request.ID = value
+	case "loc":
+		request.Location = value
+	default:
+		request.Data[key] = value
+	}
+
+	return nil
+}

internal/server/server.go

@@ -0,0 +1,32 @@
+package server
+
+import (
+	"iot-relay/internal/config"
+	"iot-relay/internal/types"
+	"log"
+	"net"
+	"time"
+)
+
+var callback types.Callback
+
+func Listen(config config.Config, _callback types.Callback) error {
+	callback = _callback
+
+	listener, err := net.Listen("tcp", config.Server.Bind)
+	if err != nil {
+		return err
+	}
+
+	for {
+		connection, err := listener.Accept()
+		if err != nil {
+			log.Println(err)
+		} else {
+			log.Printf("connection from %v", connection.RemoteAddr())
+
+			_ = connection.SetReadDeadline(time.Now().Add(time.Second * time.Duration(config.Server.Timeout)))
+			go connectionHandler(connection)
+		}
+	}
+}

internal/types/callback.go

@@ -0,0 +1,3 @@
+package types
+
+type Callback func(request Request) error

internal/types/request.go

@@ -0,0 +1,22 @@
+package types
+
+type Request struct {
+	ID       string
+	Location string
+	IP       string
+	Data     map[string]string
+}
+
+func (r Request) IsValid() bool {
+	if len(r.IP) == 0 {
+		return false
+	}
+	if len(r.ID) == 0 {
+		return false
+	}
+	if len(r.Location) == 0 {
+		return false
+	}
+
+	return true
+}