postArticle.go

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"github.com/Tensai75/nntp"
	"github.com/Tensai75/nzbparser"
)

func articlePoster() {

	for {
		select {
		case <-ctx.Done():
			return // Error somewhere, terminate
		default: // Default is must to avoid blocking
			chunk, ok := <-outputChunksChan
			if !ok {
				return
			}
			select {
			case <-ctx.Done():
				return // Error somewhere, terminate
			default: // Default is must to avoid blocking
				func() {
					defer chunksWG.Done()
					var (
						segment           nzbparser.NzbSegment
						article           nntp.Article
						partType          string
						partNumber        uint64
						totalDownloadSize uint64
						nxgHeader         string
						err               error
					)

					if filepath.Ext(chunk.Filename) == ".par2" {
						partType = "par2"
						totalDownloadSize = totalParSize
						partNumber = parPartCounter.inc()
					} else {
						partType = "data"
						totalDownloadSize = totalDataSize
						partNumber = dataPartCounter.inc()
					}

					segment.Number = int(chunk.PartNumber)
					md5Hash := GetSHA256Hash(fmt.Sprintf("%v:%v:%v", chunk.Nzb.Comment, partType, partNumber))
					segment.Id = md5Hash[:40] + "@" + md5Hash[40:61] + "." + md5Hash[61:]

					article.Header = make(map[string][]string)
					subject := ""
					poster := ""
					if conf.Obfuscate {
						subject = GetSHA256Hash(md5Hash)
					} else {
						if conf.MakeRar && conf.ObfuscateRar {
							filenameReplace := regexp.MustCompile(`^[^.]*(.*)$`)
							filename := filenameReplace.ReplaceAllString(chunk.Filename, nzb.Comment+"$1")
							subject = fmt.Sprintf("[%v/%v] \"%s\" yEnc (%v/%v)", chunk.FileNumber, chunk.TotalFiles, filename, chunk.PartNumber, chunk.TotalParts)
						} else {
							subject = fmt.Sprintf("[%v/%v] %v - \"%s\" yEnc (%v/%v)", chunk.FileNumber, chunk.TotalFiles, nzb.Comment, chunk.Filename, chunk.PartNumber, chunk.TotalParts)
						}
					}
					if conf.Obfuscate && conf.ObfuscatePoster {
						posterHash := GetSHA256Hash(subject)
						poster = posterHash[10:25] + "@" + posterHash[30:45] + "." + posterHash[50:53]
					} else {
						poster = conf.Poster
					}

					//x-nxg header
					if nxgHeader, err = encrypt(fmt.Sprintf("%v:%v:%v:%v:%v", chunk.FileNumber, chunk.TotalFiles, chunk.Filename, partType, totalDownloadSize), nzb.Comment); err != nil {
						Log.Warn("Unable to encrypt NxG header: %v", err)
					}

					article.Header["Subject"] = append(article.Header["Subject"], subject)
					article.Header["Date"] = append(article.Header["Date"], time.Now().Format(time.RFC1123))
					article.Header["From"] = append(article.Header["From"], poster)
					article.Header["Message-ID"] = append(article.Header["Message-ID"], "<"+segment.Id+">")
					article.Header["Path"] = append(article.Header["Path"], "")
					article.Header["Newsgroups"] = append(article.Header["Groups"], strings.Join(chunk.Nzb.Files[chunk.FileNumber-1].Groups, ","))
					article.Header["X-Nxg"] = append(article.Header["X-Nxg"], nxgHeader)
					article.Body = &chunk.Part

					segment.Bytes = chunk.Part.Len()
					for _, header := range article.Header {
						segment.Bytes += len(header[0])
					}

					chunksWG.Add(1)
					articlesChan <- Article{
						Segment: &segment,
						Nzb:     chunk.Nzb,
						Article: article,
						FileNo:  chunk.FileNumber,
					}
				}()
			}
		}
	}

}

func GetSHA256Hash(text string) string {
	hasher := sha256.New()
	hasher.Write([]byte(text))
	return hex.EncodeToString(hasher.Sum(nil))
}