Common stuff for all my devices' web server pages: css, login, log, ipv4, ipv6, firmware update, clock, reset info etc.

Dependents:   gps heating

Security

A password has to be set whenever there has been a software reset. Resets following faults or power on do not require a new password as the hash is restored from the RTC GPREG register.

The password is not saved on the device; instead a 32 bit hash of the password is saved. It would take 2^31 attempts to brute force the password: this could be done in under a month if an attempt were possible every millisecond. To prevent this a 200 ms delay is introduced in the reply to the login form, that gives a more reasonable 13 years to brute force the password.

Once the password is accepted a random session id is created. This is 36 bit to give six base 64 characters but without an extra delay. If an attempt could be made every ms then this would still take over a year to brute force.

The most likely attack would to use a dictionary with, say, 10 million entries against the password which would still take 20 days to do.

Revision:
129:6d9bffc72676
Parent:
128:fc9708e1d17c
Child:
130:9a5b8fe308f1
--- a/web.c	Wed Aug 28 07:12:39 2019 +0000
+++ b/web.c	Sun Sep 01 18:12:48 2019 +0000
@@ -52,13 +52,19 @@
 }
 static void handleRequest(int connectionId, int size, char* pRequestStream, uint32_t positionInRequestStream)
 {
-    struct WebConnection* pConnection = NULL;
-    if (!positionInRequestStream) pConnection = WebConnectionNew(connectionId);
-    else                          pConnection = WebConnectionOrNull(connectionId);
-    if (!pConnection)
+    struct WebConnection* pConnection;
+    if (!positionInRequestStream)
+    {
+        pConnection = WebConnectionNew(connectionId);
+    }
+    else
     {
-        LogTimeF("WebRequest - no connection corresponds to id %d\r\n", connectionId);
-        return;
+        pConnection = WebConnectionOrNull(connectionId);
+        if (!pConnection)
+        {
+            LogTimeF("WebRequest - no connection corresponds to id %d\r\n", connectionId);
+            return;
+        }
     }
     
     pConnection->delayUntil = MsTimerCount; //Default to no delay unless modified;
@@ -120,7 +126,7 @@
 static bool pollSomethingToSend(int connectionId, bool clientFinished) //returns true if finished; false if not; 
 {
     struct WebConnection* pConnection = WebConnectionOrNull(connectionId);
-    if (!pConnection) return false;
+    if (!pConnection) return false; //Protects the gap between the connection being established and the request being started
     
     if (!pConnection->toDo)
     {