1 files changed, 142 insertions, 0 deletions
diff --git a/session.go b/session.go
new file mode 100644
index 0000000..a06a344
--- /dev/null
+++ b/session.go
@@ -0,0 +1,142 @@
+package main
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/hex"
+	"net/http"
+	"sync"
+	"time"
+)
+
+type TSession struct {
+	SessionID []byte
+	IPAddress string
+	Expires   time.Time
+	AccountID int
+}
+
+// IMPORTANT(fusion): Ideally you'd save sessions in a database to reduce memory
+// usage and to make them persistent with server restarts. In reality, we should
+// have a low amount of sessions and a high server uptime, making the memory usage
+// here minimal. We can always turn this into a LRU cache with a set maximum number
+// of sessions.
+
+var (
+	g_SessionsMutex sync.Mutex
+	g_Sessions      []TSession
+)
+
+func GenerateSessionID() []byte {
+	var SessionID [32]byte
+	_, Err := rand.Read(SessionID[:])
+	if Err != nil {
+		g_LogErr.Printf("Failed to generate session id: %v", Err)
+		return nil
+	}
+
+	return SessionID[:]
+}
+
+func GetRequestSessionID(Request *http.Request) []byte {
+	Cookie, Err := Request.Cookie("GOSESSID")
+	if Err != nil {
+		return nil
+	}
+
+	SessionID, Err := hex.DecodeString(Cookie.Value)
+	if Err != nil {
+		g_LogErr.Printf("Failed to decode session id: %v", Err)
+		return nil
+	}
+
+	if len(SessionID) != 32 {
+		g_LogErr.Printf("Invalid session id size %v (expected 32)", len(SessionID))
+		return nil
+	}
+
+	return SessionID
+}
+
+func SessionLookup(SessionID []byte, IPAddress string) int {
+	AccountID := 0
+	if SessionID != nil && IPAddress != "" {
+		g_SessionsMutex.Lock()
+		defer g_SessionsMutex.Unlock()
+		for Index := 0; Index < len(g_Sessions); Index += 1 {
+			Session := &g_Sessions[Index]
+
+			if time.Until(Session.Expires) <= 0 {
+				g_Sessions = SwapAndPop(g_Sessions, Index)
+				Index -= 1
+				continue
+			}
+
+			if bytes.Equal(Session.SessionID, SessionID) && Session.IPAddress == IPAddress {
+				AccountID = Session.AccountID
+				break
+			}
+		}
+	}
+	return AccountID
+}
+
+func SessionStart(Context *THttpRequestContext, AccountID int) {
+	if AccountID <= 0 {
+		g_LogErr.Printf("Trying to start session with invalid account id %v", AccountID)
+		return
+	}
+
+	SessionID := make([]byte, 32)
+	if _, Err := rand.Read(SessionID); Err != nil {
+		g_LogErr.Printf("Failed to generate session id: %v", Err)
+		return
+	}
+
+	Context.SessionID = SessionID
+	Context.AccountID = AccountID
+	Expires := time.Now().Add(time.Hour)
+	http.SetCookie(Context.Writer, &http.Cookie{
+		Name:     "GOSESSID",
+		Value:    hex.EncodeToString(SessionID),
+		Path:     "/",
+		Expires:  Expires,
+		Secure:   false, // TODO(fusion): Enable this when HTTPS is enabled (?).
+		HttpOnly: true,
+	})
+
+	g_SessionsMutex.Lock()
+	defer g_SessionsMutex.Unlock()
+	g_Sessions = append(g_Sessions,
+		TSession{
+			SessionID: SessionID,
+			IPAddress: Context.IPAddress,
+			Expires:   Expires,
+			AccountID: AccountID,
+		})
+}
+
+func SessionEnd(Context *THttpRequestContext) {
+	if Context.SessionID == nil {
+		return
+	}
+
+	http.SetCookie(Context.Writer, &http.Cookie{
+		Name:    "GOSESSID",
+		Value:   "",
+		Path:    "/",
+		Expires: time.Unix(0, 0),
+	})
+
+	g_SessionsMutex.Lock()
+	defer g_SessionsMutex.Unlock()
+	for Index := 0; Index < len(g_Sessions); Index += 1 {
+		Session := &g_Sessions[Index]
+		if bytes.Equal(Session.SessionID, Context.SessionID) && Session.IPAddress == Context.IPAddress {
+			g_Sessions[Index] = g_Sessions[len(g_Sessions)-1]
+			g_Sessions[len(g_Sessions)-1] = TSession{}
+			g_Sessions = g_Sessions[:len(g_Sessions)-1]
+			break
+		}
+	}
+}