From 4a105d6ba6ba726a22840bac6d2b8313d707efbc Mon Sep 17 00:00:00 2001
From: Darren VanBuren <onekopaka@theoks.net>
Date: Wed, 21 Dec 2016 23:01:52 -0800
Subject: [PATCH] First shot at using regex for referrer check to improve
 situation on gochan.org

---
 src/server.go | 28 ++++++++++++++++++++--------
 src/types.go  |  5 +++++
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/src/server.go b/src/server.go
index e082e4e3..c79efa97 100755
--- a/src/server.go
+++ b/src/server.go
@@ -10,18 +10,20 @@ import (
 	"net/url"
 	"os"
 	"path"
+	"regexp"
 	"strconv"
 	"strings"
 )
 
 var (
-	form       url.Values
-	header     http.Header
-	cookies    []*http.Cookie
-	writer     http.ResponseWriter
-	request    http.Request
-	exit_error bool
-	server     *GochanServer
+	form          url.Values
+	header        http.Header
+	cookies       []*http.Cookie
+	writer        http.ResponseWriter
+	request       http.Request
+	exit_error    bool
+	server        *GochanServer
+	referrerRegex *regexp.Regexp
 )
 
 type GochanServer struct {
@@ -179,7 +181,17 @@ func getRealIP(r *http.Request) (ip string) {
 }
 
 func validReferrer(request http.Request) (valid bool) {
-	valid = !(request.Referer() == "" || len(request.Referer()) < len(config.SiteDomain) || request.Referer()[7:len(config.SiteDomain)+7] != config.SiteDomain)
+	if referrerRegex == nil {
+		referrerRegex, err := regexp.Compile(config.DomainRegex)
+		if err != nil || referrerRegex == nil {
+			valid = false
+			return
+		}
+	}
+
+	valid = referrerRegex.MatchString(request.Referer())
+	// Old Referrer check.
+	// valid = !(request.Referer() == "" || len(request.Referer()) < len(config.SiteDomain) || request.Referer()[7:len(config.SiteDomain)+7] != config.SiteDomain)
 	return
 }
 
diff --git a/src/types.go b/src/types.go
index 06132d4a..f7dbe1df 100644
--- a/src/types.go
+++ b/src/types.go
@@ -293,6 +293,7 @@ type GochanConfig struct {
 	SiteHeaderURL string
 	SiteWebfolder string
 	SiteDomain    string
+	DomainRegex   string
 
 	Styles_img       []string
 	DefaultStyle_img string
@@ -481,6 +482,10 @@ func initConfig() {
 		os.Exit(2)
 	}
 
+	if config.DomainRegex == "" {
+		config.DomainRegex = "/(https|http):\\/\\/(" + config.SiteDomain + ")\\/(.*)/"
+	}
+
 	if config.Styles_img == nil {
 		println(0, "Styles_img not set in gochan.json, halting.")
 		os.Exit(2)