add MCC/MNC name lookup to *3gpp_uli converter

data/scripts/gen_mccmnc.go

@@ -0,0 +1,114 @@
+//go:build ignore
+
+// Parses Wireshark's packet-e212.c and generates utils/mccmnc_data.go.
+// Run: go generate ./utils/...
+package main
+
+import (
+	"fmt"
+	"go/format"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+const wiresharkURL = "https://raw.githubusercontent.com/wireshark/wireshark/master/epan/dissectors/packet-e212.c"
+
+// matches entries like { 123, "Some Name" } in C value_string arrays
+var entryRe = regexp.MustCompile(`\{\s*(\d+),\s*"([^"]+)"\s*\}`)
+
+func main() {
+	log.SetFlags(0)
+
+	src := fetchSource()
+
+	countries := parseTable(src, "E212_codes[]", func(code int) string {
+		return fmt.Sprintf("%03d", code)
+	})
+	networks := parseTable(src, "mcc_mnc_2digits_codes[]", func(code int) string {
+		return fmt.Sprintf("%03d-%02d", code/100, code%100)
+	})
+	// 3-digit MNC: only add if no 2-digit entry exists for the same key
+	for k, v := range parseTable(src, "mcc_mnc_3digits_codes[]", func(code int) string {
+		return fmt.Sprintf("%03d-%03d", code/1000, code%1000)
+	}) {
+		if _, ok := networks[k]; !ok {
+			networks[k] = v
+		}
+	}
+
+	var buf strings.Builder
+	buf.WriteString("// Code generated by gen_mccmnc from Wireshark's packet-e212.c; DO NOT EDIT.\n\npackage utils\n\n")
+	writeMap(&buf, "mccCountry", "MCC to country name (ITU-T E.212)", countries)
+	writeMap(&buf, "mccmncNetwork", "MCC-MNC to network/operator name (ITU-T E.212)", networks)
+
+	formatted, err := format.Source([]byte(buf.String()))
+	if err != nil {
+		log.Fatalf("gofmt: %v", err)
+	}
+	if err := os.WriteFile("mccmnc_data.go", formatted, 0644); err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("generated mccmnc_data.go: %d countries, %d networks\n", len(countries), len(networks))
+}
+
+func fetchSource() string {
+	resp, err := http.Get(wiresharkURL)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer resp.Body.Close()
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return string(body)
+}
+
+func parseTable(src, name string, formatKey func(int) string) map[string]string {
+	block := extractBlock(src, name)
+	if block == "" {
+		log.Fatalf("table %s not found", name)
+	}
+	result := make(map[string]string)
+	for _, m := range entryRe.FindAllStringSubmatch(block, -1) {
+		if m[2] == "Unassigned" || m[2] == "Unset" {
+			continue
+		}
+		code, _ := strconv.Atoi(m[1])
+		result[formatKey(code)] = m[2]
+	}
+	return result
+}
+
+// extractBlock returns the body of a C value_string array, up to its { 0, NULL } terminator.
+func extractBlock(src, name string) string {
+	marker := "value_string " + name + " = {"
+	start := strings.Index(src, marker)
+	if start < 0 {
+		return ""
+	}
+	end := strings.Index(src[start:], "{ 0, NULL }")
+	if end < 0 {
+		return ""
+	}
+	return src[start : start+end]
+}
+
+func writeMap(buf *strings.Builder, varName, comment string, m map[string]string) {
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	fmt.Fprintf(buf, "// %s maps %s.\nvar %s = map[string]string{\n", varName, comment, varName)
+	for _, k := range keys {
+		fmt.Fprintf(buf, "\t%q: %q,\n", k, m[k])
+	}
+	buf.WriteString("}\n\n")
+}