go_sysutils/net/main.go

package main

import (
	"bytes"
	_ "encoding/csv"
	"fmt"
	"os"
	"strconv"
	"strings"

	"github.com/jszwec/csvutil"

	"r00t2.io/sysutils/net/ports"
	"r00t2.io/sysutils/net/protos"
	"r00t2.io/sysutils/paths"
)

// I really don't get all the slobbering over interfaces. They seem... pointless.
// Because now I have to write multiple parsers with largely duplicate code.
// Massive code duplication is, apparently, Idiomatic Go(TM).
// I miss python.
func parsePort(src *[]byte, dst []ports.IPPort, outBytes *[]byte) (err error) {

	var tName string
	var varName string
	var s string
	var buf bytes.Buffer
	var allports []string

	buf.Write([]byte("package ports\n\n"))

	if err = csvutil.Unmarshal(*src, &dst); err != nil {
		return
	}

	buf.Write([]byte("var (\n"))

	for _, i := range dst {

		// tName = fmt.Sprintf("%v", i.ServiceName)
		tName = strings.ToLower(i.ServiceName)
		varName = fmt.Sprintf("RegisteredPort_%v%v", tName, int(i.Number))

		s = fmt.Sprintf("\t%v := %#v\n", varName, &i)
		buf.Write([]byte(s))
	}

	buf.Write([]byte(")\n\n"))

	// Write the easy collections.
	buf.Write([]byte("var (\n"))
	buf.Write([]byte("\tAllRegisteredPorts []*IPPort = {\n"))
	for _, i := range allports {
		buf.Write([]byte(fmt.Sprintf("\t\t%v,\n", i)))
	}
	buf.Write([]byte(")\n\n)\n"))

	*outBytes = buf.Bytes()

	return
}

func parseProto(src *[]byte, dst []protos.IPProto, outBytes *[]byte) (err error) {

	var tName string
	var varName string
	var s string
	var buf bytes.Buffer
	var allprotos []string

	buf.Write([]byte("package protos\n\n"))

	if err = csvutil.Unmarshal(*src, &dst); err != nil {
		return
	}

	buf.Write([]byte("var (\n"))

	for _, i := range dst {

		tName = fmt.Sprintf("%v", i.Name)
		varName = fmt.Sprintf("RegisteredProto%v%v", tName, strconv.Itoa(int(i.Number)))

		allprotos = append(allprotos, varName)

		s = fmt.Sprintf("\t%v := %#v\n", varName, &i)
		buf.Write([]byte(s))
	}

	buf.Write([]byte(")\n\n"))

	// Write the easy collections.
	buf.Write([]byte("var (\n"))
	buf.Write([]byte("\tAllRegisteredProtos []*IPProto = {\n"))
	for _, i := range allprotos {
		buf.Write([]byte(fmt.Sprintf("\t\t%v,\n", i)))
	}
	buf.Write([]byte(")\n\n)\n"))

	*outBytes = buf.Bytes()

	return
}

func write(path string, b []byte) (err error) {

	if err = paths.RealPath(&path); err != nil {
		return
	}
	if err = os.WriteFile(path, b, 0644); err != nil {
		return
	}

	return
}

func main() {

	var dlbytes *[]byte // This is the raw downloaded CSV.
	// var rows [][]string  // This is the parsed CSV.
	var err error

	urls := map[string]map[string]string{
		// Protos needs to be first so ports can reference them.
		// TODO.
		"protos": {
			"url":  protosUrl,
			"file": protosFile,
		},
		"ports": {
			"url":  portsUrl,
			"file": portsFile,
		},
	}

	rendered := map[string]*[]byte{
		"protos": &[]byte{},
		"ports":  &[]byte{},
	}

	for t, d := range urls {

		var url string
		var fpath string
		var ok bool

		if url, ok = d["url"]; !ok {
			fmt.Printf("URL does not exist for %v; skipping.\n", t)
			continue
		}
		if fpath, ok = d["file"]; !ok {
			fmt.Printf("File path does not exist for %v; skipping.\n", t)
			continue
		} else {
			if err = paths.RealPath(&fpath); err != nil {
				fmt.Printf("Cannot resolve file path for %v; skipping.\n", t)
				continue
			}
		}

		if dlbytes, err = download(url); err != nil {
			fmt.Printf("Could not download '%v' for %v (skipping):\n", url, t)
			fmt.Println(err)
			continue
		}

		// I *could* set up a variable that refers to the proper func and set that func in an if block above...
		// But then I'd have to use reflection and it gets gross and hacky.  This is a lot more performant even though it's a lot
		// more verbose. Write it once, run it many times...
		if t == "ports" {

			var objs []ports.IPPort

			if err = parsePort(dlbytes, objs, rendered[t]); err != nil {
				fmt.Printf("Could not parse %v (skipping):\n", t)
				fmt.Println(err)
				continue
			}

		} else { // t == "proto"

			var objs []protos.IPProto

			if err = parseProto(dlbytes, objs, rendered[t]); err != nil {
				fmt.Printf("Could not parse %v (skipping):\n", t)
				fmt.Println(err)
				continue
			}

		}

		if err = write(fpath, *rendered[t]); err != nil {
			fmt.Printf("Could not write to '%v' for %v (skipping):\n", fpath, t)
			fmt.Println(err)
			continue
		}

	}
}