From 333c79701d2a04603be12dd7852679fcd4353729 Mon Sep 17 00:00:00 2001
From: MikeIsAStar <99037623+MikeIsAStar@users.noreply.github.com>
Date: Tue, 5 Dec 2023 22:05:00 -0500
Subject: [PATCH] DLS1: Implement the 'count' action

---
 common/strings.go | 19 +++++++++++++++++++
 dlc/README.md     |  3 +++
 nas/auth.go       | 30 +++++++++++++++++++++++++++++-
 3 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 dlc/README.md

diff --git a/common/strings.go b/common/strings.go
index f342c61..f7b3a78 100644
--- a/common/strings.go
+++ b/common/strings.go
@@ -34,3 +34,22 @@ func GetString(buf []byte) string {
 	nullTerminator := bytes.IndexByte(buf, 0)
 	return string(buf[:nullTerminator])
 }
+
+// Checks if the given string is composed exclusively of uppercase alphanumeric characters.
+func IsUppercaseAlphanumeric(str string) bool {
+	strLength := len(str)
+
+	if strLength == 0 {
+		return false
+	}
+
+	for i := 0; i < strLength; i++ {
+		c := str[i]
+
+		if (c < '0' || c > '9') && (c < 'A' || c > 'Z') {
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/dlc/README.md b/dlc/README.md
new file mode 100644
index 0000000..28fccfa
--- /dev/null
+++ b/dlc/README.md
@@ -0,0 +1,3 @@
+# Downloadable Content
+
+Create a folder in this directory using the game's game code as the folder name. Afterwards, place downloadable content into the aforementioned folder.
diff --git a/nas/auth.go b/nas/auth.go
index 141d58c..3accfe9 100644
--- a/nas/auth.go
+++ b/nas/auth.go
@@ -5,6 +5,8 @@ import (
 	"github.com/logrusorgru/aurora/v3"
 	"net/http"
 	"net/url"
+	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
@@ -13,6 +15,10 @@ import (
 	"wwfc/logging"
 )
 
+var (
+	dlcDir = "./dlc"
+)
+
 func handleAuthRequest(moduleName string, w http.ResponseWriter, r *http.Request) {
 	err := r.ParseForm()
 	if err != nil {
@@ -87,6 +93,13 @@ func handleAuthRequest(moduleName string, w http.ResponseWriter, r *http.Request
 			return
 		}
 
+		rhgamecd, ok := fields["rhgamecd"]
+		if !ok || !isValidRhgamecd(rhgamecd) {
+			logging.Error(moduleName, "Missing or invalid rhgamecd")
+			replyHTTPError(w, 400, "400 Bad Request")
+			return
+		}
+
 		switch action {
 		case "count":
 			response = []byte(dlsCount(moduleName, fields))
@@ -210,7 +223,22 @@ func handleProfanity(moduleName string, fields map[string]string) map[string]str
 }
 
 func dlsCount(moduleName string, fields map[string]string) string {
-	return "0"
+	dlcFolder := filepath.Join(dlcDir, fields["rhgamecd"])
+
+	dir, ok := os.ReadDir(dlcFolder)
+	if ok != nil {
+		return "0"
+	}
+
+	return strconv.Itoa(len(dir))
+}
+
+func isValidRhgamecd(rhgamecd string) bool {
+	if len(rhgamecd) != 4 {
+		return false
+	}
+
+	return common.IsUppercaseAlphanumeric(rhgamecd)
 }
 
 func getDateTime() string {