From 77cb45dbecb94e30d12e12263723951e082285d4 Mon Sep 17 00:00:00 2001
From: Richard Patel <terorie@alphakevin.club>
Date: Sun, 28 Oct 2018 18:37:18 +0100
Subject: [PATCH] Detect directory symlinks

---
 crawl.go  | 17 ++++++++++++++---
 errors.go |  8 ++++++++
 main.go   |  3 +++
 worker.go | 17 +++++++++++++++--
 4 files changed, 40 insertions(+), 5 deletions(-)
 create mode 100644 errors.go

diff --git a/crawl.go b/crawl.go
index 7532fef..0e999e1 100644
--- a/crawl.go
+++ b/crawl.go
@@ -2,10 +2,11 @@ package main
 
 import (
 	"bytes"
-	"errors"
+	"encoding/base64"
 	"fmt"
 	"github.com/sirupsen/logrus"
 	"github.com/valyala/fasthttp"
+	"golang.org/x/crypto/blake2b"
 	"golang.org/x/net/html"
 	"golang.org/x/net/html/atom"
 	"net/url"
@@ -16,8 +17,6 @@ import (
 )
 
 var client fasthttp.Client
-var ErrRateLimit = errors.New("too many requests")
-var ErrForbidden = errors.New("access denied")
 
 func GetDir(j *Job, f *File) (links []url.URL, err error) {
 	f.IsDir = true
@@ -146,6 +145,18 @@ func GetFile(u url.URL, f *File) (err error) {
 	return nil
 }
 
+func (f *File) HashDir(links []url.URL) string {
+	h, _ := blake2b.New256(nil)
+	h.Write([]byte(f.Name))
+	for _, link := range links {
+		fileName := path.Base(link.Path)
+		h.Write([]byte(fileName))
+	}
+	sum := h.Sum(nil)
+	b64sum := base64.StdEncoding.EncodeToString(sum)
+	return b64sum
+}
+
 func (f *File) ParseHeader(h []byte) {
 	var k1, k2 int
 	var v1, v2 int
diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..316a108
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,8 @@
+package main
+
+import "errors"
+
+var ErrRateLimit = errors.New("too many requests")
+var ErrForbidden = errors.New("access denied")
+var ErrKnown     = errors.New("already crawled")
+
diff --git a/main.go b/main.go
index 86ca871..2371d82 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
 	"net/url"
 	"os"
@@ -69,6 +70,8 @@ func cmdCrawler(clic *cli.Context) error {
 	// Wait for all jobs to finish
 	globalWait.Wait()
 
+	logrus.Info("All dirs processed!")
+
 	return nil
 }
 
diff --git a/worker.go b/worker.go
index 49793b3..d9c52b6 100644
--- a/worker.go
+++ b/worker.go
@@ -31,6 +31,9 @@ func (w WorkerContext) step(job Job) {
 
 	newJobs, err := DoJob(&job, &f)
 	atomic.AddUint64(&totalStarted, 1)
+	if err == ErrKnown {
+		return
+	}
 
 	if err != nil {
 		job.Fails++
@@ -64,9 +67,8 @@ func (w WorkerContext) step(job Job) {
 }
 
 func DoJob(job *Job, f *File) (newJobs []Job, err error) {
-	// File
 	if strings.HasSuffix(job.Uri.Path, "/") {
-		// Dir
+		// Load directory
 		links, err := GetDir(job, f)
 		if err != nil {
 			logrus.WithError(err).
@@ -74,7 +76,17 @@ func DoJob(job *Job, f *File) (newJobs []Job, err error) {
 				Error("Failed getting dir")
 			return nil, err
 		}
+
+		// Hash directory
+		hash := f.HashDir(links)
+
+		// Skip symlinked dirs
+		if _, old := job.OD.Scanned.LoadOrStore(hash, true); old {
+			return nil, ErrKnown
+		}
+
 		for _, link := range links {
+			// Skip already queued links
 			if _, old := job.OD.Scanned.LoadOrStore(link, true); old {
 				continue
 			}
@@ -91,6 +103,7 @@ func DoJob(job *Job, f *File) (newJobs []Job, err error) {
 			"files": len(links),
 		}).Debug("Listed")
 	} else {
+		// Load file
 		err := GetFile(job.Uri, f)
 		if err != nil {
 			logrus.WithError(err).