feat(usenet): implement full NNTP download pipeline

Complete usenet download support for unarr CLI: - NZB XML parser with password extraction from <head> meta - yEnc decoder with CRC32 verification - NNTP client with TLS, auth, and connection pool (up to 10 conns) - Segment downloader with parallel workers and progress reporting - Post-processing: par2 verify/repair, unrar/7z extraction with password support - Agent client methods: SearchNzbs, DownloadNzb, GetUsenetCredentials - UsenetDownloader implementing full Downloader interface - Daemon wiring: UsenetDownloader passed to Manager E2E tested: Oppenheimer 1080p (2.94 GB) downloaded via NNTP in 77.6s.
2026-03-28 21:12:12 +01:00 · 2026-03-28 21:12:12 +01:00 · e332c0a6e4
commit e332c0a6e4
parent 5f337eebd7
15 changed files with 3016 additions and 23 deletions
--- a/internal/usenet/postprocess/par2.go
+++ b/internal/usenet/postprocess/par2.go
@ -0,0 +1,65 @@
+package postprocess
+
+import (
+	"fmt"
+	"log"
+	"os/exec"
+	"strings"
+)
+
+// Par2Available checks if par2cmdline is installed.
+func Par2Available() bool {
+	_, err := exec.LookPath("par2")
+	return err == nil
+}
+
+// Par2Verify verifies files using a par2 file.
+// Returns nil if verification passes, error otherwise.
+func Par2Verify(par2File string) error {
+	if !Par2Available() {
+		log.Printf("[usenet] par2 not installed, skipping verification")
+		return nil
+	}
+
+	cmd := exec.Command("par2", "verify", par2File)
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		outStr := string(output)
+		// Check if repair is possible
+		if strings.Contains(outStr, "Repair is possible") {
+			return &Par2RepairableError{Par2File: par2File}
+		}
+		if strings.Contains(outStr, "Repair is not possible") {
+			return fmt.Errorf("par2: verification failed and repair not possible:\n%s", outStr)
+		}
+		return fmt.Errorf("par2 verify: %w\n%s", err, outStr)
+	}
+
+	log.Printf("[usenet] par2: verification OK")
+	return nil
+}
+
+// Par2Repair attempts to repair files using par2 parity data.
+func Par2Repair(par2File string) error {
+	if !Par2Available() {
+		return fmt.Errorf("par2 not installed")
+	}
+
+	cmd := exec.Command("par2", "repair", par2File)
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("par2 repair: %w\n%s", err, output)
+	}
+
+	log.Printf("[usenet] par2: repair successful")
+	return nil
+}
+
+// Par2RepairableError indicates verification failed but repair is possible.
+type Par2RepairableError struct {
+	Par2File string
+}
+
+func (e *Par2RepairableError) Error() string {
+	return fmt.Sprintf("par2: verification failed, repair possible: %s", e.Par2File)
+}