[+] initial version

.gitignore

@@ -46,4 +46,7 @@ go.work
 go.work.sum
 
 # env file
-.env
+.env
+
+# geofeed file
+geofeed.csv

README.md

@@ -0,0 +1,38 @@
+![geofeed-validator](https://socialify.git.ci/realSunyz/geofeed-validator/image?description=1&descriptionEditable=&font=Jost&language=1&name=1&owner=1&pattern=Circuit%20Board&theme=Auto)
+
+This utility is used to validate the format of geofeed files.
+
+> [!NOTE]
+> The project is still under development. The code on the main branch is stable and usable.
+
+## Usage
+
+### Compile
+
+```bash
+# Clone the repository
+git clone https://github.com/realSunyz/geofeed-validator.git
+
+# Navigate to the directory
+cd geofeed-validator/src
+
+# Synchronize and clean up dependencies
+go mod tidy
+
+# Build the executable file
+go build -o geofeed-validator
+```
+
+### Run
+```bash
+./geofeed-validator <path_to_geofeed.csv>
+```
+
+## Contributing
+
+Issues and Pull Requests are definitely welcome!
+
+Please make sure you have tested your code locally before submitting a PR.
+
+## License
+This project is licensed under the MIT License - see the [LICENSE](https://github.com/realSunyz/geofeed-validator/blob/main/LICENSE) file for details.

src/go.mod

@@ -0,0 +1,3 @@
+module github.com/realsunyz/geofeed-validator
+
+go 1.23.2

src/validator.go

@@ -0,0 +1,164 @@
+// validator.go
+// author: Yanzheng SUN (realSunyz)
+
+package main
+
+import (
+	"bufio"
+	"embed"
+	"encoding/csv"
+	"encoding/json"
+	"fmt"
+	"net"
+	"os"
+	"strings"
+)
+
+const (
+	Reset   = "\033[0m"
+	Red     = "\033[31m"
+	Green   = "\033[32m"
+	Yellow  = "\033[33m"
+	Magenta = "\033[35m"
+	Cyan    = "\033[36m"
+)
+
+type Country struct {
+	Name string `json:"name"`
+	Code string `json:"code"`
+}
+
+type Subdivision struct {
+	Name string `json:"name"`
+	Code string `json:"code"`
+}
+
+type SubdivisionMap map[string][]Subdivision
+
+//go:embed data/*.json
+var dataFS embed.FS
+
+func readJSON(filename string, v interface{}) error {
+	data, err := dataFS.ReadFile(filename)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(data, v)
+}
+
+func validateGeofeed(geofeedFile string, countries []Country, subdivisions SubdivisionMap) []string {
+
+	countryMap := make(map[string]bool)
+	for _, country := range countries {
+		countryMap[country.Code] = true
+	}
+
+	file, err := os.Open(geofeedFile)
+	if err != nil {
+		return []string{fmt.Sprintf("Failed to open geofeed file: %v", err)}
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	lineNumber := 0
+	var errors []string
+
+	for scanner.Scan() {
+		lineNumber++
+		line := scanner.Text()
+
+		// Skip blank lines
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+
+		// Skip comment lines
+		if strings.HasPrefix(strings.TrimSpace(line), "#") {
+			continue
+		}
+
+		reader := csv.NewReader(strings.NewReader(line))
+		reader.FieldsPerRecord = -1
+		record, _ := reader.Read()
+
+		// Validate geofeed format (prefix, country_code, subdivision_code, city, postal_code)
+		if len(record) < 5 {
+			errors = append(errors, fmt.Sprintf("Line %d: invalid "+Magenta+"geofeed "+Reset+"format", lineNumber))
+			continue
+		}
+		prefix, countryCode, subdivisionCode := record[0], record[1], record[2]
+
+		// Validate prefix format
+		_, _, prefixErr := net.ParseCIDR(prefix)
+		if prefixErr != nil {
+			errors = append(errors, fmt.Sprintf("Line %d: invalid "+Magenta+"prefix "+Reset+"format ("+Cyan+"%s"+Reset+")", lineNumber, prefix))
+			// continue
+		}
+
+		// Skip empty country code
+		if countryCode == "" {
+			continue
+		}
+
+		// Validate country code
+		if !countryMap[countryCode] {
+			errors = append(errors, fmt.Sprintf("Line %d: invalid "+Magenta+"country code "+Reset+"("+Cyan+"%s"+Reset+")", lineNumber, countryCode))
+			continue
+		}
+
+		// Skip empty subdivision code
+		if subdivisionCode == "" {
+			continue
+		}
+
+		// Validate subdivision code
+		validSubdivision := false
+		for _, subdivision := range subdivisions[countryCode] {
+			if subdivision.Code == subdivisionCode {
+				validSubdivision = true
+				break
+			}
+		}
+		if !validSubdivision {
+			errors = append(errors, fmt.Sprintf("Line %d: invalid "+Magenta+"subdivision code "+Reset+"("+Cyan+"%s"+Reset+") "+"for country ("+Cyan+"%s"+Reset+")", lineNumber, subdivisionCode, countryCode))
+		}
+	}
+
+	return errors
+}
+
+func main() {
+	countryFile := "data/iso3166-1.json"
+	subdivisionFile := "data/iso3166-2.json"
+
+	if len(os.Args) < 2 {
+		fmt.Println("Usage: ./geofeed-validator <path_to_geofeed.csv>")
+		os.Exit(1)
+	}
+
+	geofeedFile := os.Args[1]
+
+	var countries []Country
+	var subdivisions SubdivisionMap
+
+	if err := readJSON(countryFile, &countries); err != nil {
+		fmt.Printf("Failed to load countries: %v\n", err)
+		return
+	}
+
+	if err := readJSON(subdivisionFile, &subdivisions); err != nil {
+		fmt.Printf("Failed to load subdivisions: %v\n", err)
+		return
+	}
+
+	errors := validateGeofeed(geofeedFile, countries, subdivisions)
+
+	if len(errors) == 0 {
+		fmt.Println("Congratulations! Your geofeed file is " + Green + "VALID" + Reset + ".")
+	} else {
+		fmt.Println("Your geofeed file is " + Red + "INVALID" + Reset + ":")
+		for _, err := range errors {
+			fmt.Println("- " + err)
+		}
+	}
+}