Tcp: Proper error reporting for invalid values of windowScalingFactor…

… and advertisedWindow NED parameters Also: fix RFC reference
inet-framework · Sep 25, 2023 · 6dad206 · 6dad206
1 parent 95df563
commit 6dad206
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Showing 3 changed files with 22 additions and 13 deletions.
diff --git a/src/inet/transportlayer/tcp/TcpConnection.h b/src/inet/transportlayer/tcp/TcpConnection.h
@@ -33,7 +33,7 @@ class TcpAlgorithm;
 //@}
 
 #define MAX_SYN_REXMIT_COUNT          12  // will only be used with SYN+ACK: with SYN CONN_ESTAB occurs sooner
-#define TCP_MAX_WIN                   65535  // 65535 bytes, largest value (16 bit) for (unscaled) window size
+#define TCP_MAX_WIN                   65535lu  // 65535 bytes, largest value (16 bit) for (unscaled) window size
 #define TCP_MAX_WIN_SCALED            0x3fffffffL // 2^30-1 bytes, largest value for scaled window size
 #define MAX_SACK_BLOCKS               60  // will only be used with SACK
 #define PAWS_IDLE_TIME_THRESH         (24 * 24 * 3600)  // 24 days in seconds (RFC 1323)

diff --git a/src/inet/transportlayer/tcp/TcpConnectionState.msg b/src/inet/transportlayer/tcp/TcpConnectionState.msg
@@ -167,7 +167,7 @@ struct TcpStateVariables
     bool afterRto = false;                      // set at RTO, reset when snd_nxt == snd_max or snd_una == snd_max
 
     // WINDOW_SCALE related variables
-    bool ws_support = false;                    // set if the host supports Window Scale (header option) (RFC 1322)
+    bool ws_support = false;                    // set if the host supports Window Scale (header option) (RFC 1323)
     bool ws_enabled = false;                    // set if the connection uses Window Scale (header option)
     int  ws_manual_scale = -1;                  // the value of scale parameter if it was set manually (-1 otherwise)
     bool snd_ws = false;                        // set if initial WINDOW_SCALE has been sent

diff --git a/src/inet/transportlayer/tcp/TcpConnectionUtil.cc b/src/inet/transportlayer/tcp/TcpConnectionUtil.cc
@@ -435,29 +435,38 @@ void TcpConnection::initConnection(TcpOpenCommand *openCmd)
 
 void TcpConnection::configureStateVariables()
 {
-    state->dupthresh = tcpMain->par("dupthresh");
-    long advertisedWindowPar = tcpMain->par("advertisedWindow");
-    state->ws_support = tcpMain->par("windowScalingSupport"); // if set, this means that current host supports WS (RFC 1323)
-    state->ws_manual_scale = tcpMain->par("windowScalingFactor"); // scaling factor (set manually) to help for Tcp validation
-    state->ecnWillingness = tcpMain->par("ecnWillingness"); // if set, current host is willing to use ECN
-    if ((!state->ws_support && advertisedWindowPar > TCP_MAX_WIN) || advertisedWindowPar <= 0 || advertisedWindowPar > TCP_MAX_WIN_SCALED)
-        throw cRuntimeError("Invalid advertisedWindow parameter: %ld", advertisedWindowPar);
+    uint32_t advertisedWindow = tcpMain->par("advertisedWindow");
+    state->ws_support = tcpMain->par("windowScalingSupport");
+    int windowScalingFactor = tcpMain->par("windowScalingFactor");
+    if (windowScalingFactor < -1 || windowScalingFactor > 14)
+        throw cRuntimeError("Invalid parameter value windowScalingFactor=%d -- valid values are 0..14, and -1 for automatic selection based on advertisedWindow", windowScalingFactor);
+    if (state->ws_support) {
+        uint32_t maxAdvertisedWindow = TCP_MAX_WIN << (windowScalingFactor==-1 ? 14 : windowScalingFactor);
+        if (advertisedWindow > maxAdvertisedWindow)
+            throw cRuntimeError("Invalid parameter value: advertisedWindow=%" PRIu32 " exceeds representable maximum %" PRIu32 " with windowScalingFactor=%d", advertisedWindow, maxAdvertisedWindow, windowScalingFactor);
+    }
+    else if (advertisedWindow > TCP_MAX_WIN) {
+        throw cRuntimeError("Invalid parameter value: advertisedWindow=%" PRIu32 " exceeds representable maximum %lu, try turning on window scaling (windowScalingSupport=true)", advertisedWindow, TCP_MAX_WIN);
+    }
+    state->ws_manual_scale = windowScalingFactor;
 
-    state->rcv_wnd = advertisedWindowPar;
-    state->rcv_adv = advertisedWindowPar;
+    state->rcv_wnd = advertisedWindow;
+    state->rcv_adv = advertisedWindow;
 
-    if (state->ws_support && advertisedWindowPar > TCP_MAX_WIN) {
+    if (state->ws_support && advertisedWindow > TCP_MAX_WIN) {
         state->rcv_wnd = TCP_MAX_WIN; // we cannot to guarantee that the other end is also supporting the Window Scale (header option) (RFC 1322)
         state->rcv_adv = TCP_MAX_WIN; // therefore TCP_MAX_WIN is used as initial value for rcv_wnd and rcv_adv
     }
 
-    state->maxRcvBuffer = advertisedWindowPar;
+    state->maxRcvBuffer = advertisedWindow;
     state->delayed_acks_enabled = tcpMain->par("delayedAcksEnabled"); // delayed ACK algorithm (RFC 1122) enabled/disabled
     state->nagle_enabled = tcpMain->par("nagleEnabled"); // Nagle's algorithm (RFC 896) enabled/disabled
     state->limited_transmit_enabled = tcpMain->par("limitedTransmitEnabled"); // Limited Transmit algorithm (RFC 3042) enabled/disabled
     state->increased_IW_enabled = tcpMain->par("increasedIWEnabled"); // Increased Initial Window (RFC 3390) enabled/disabled
     state->snd_mss = tcpMain->par("mss"); // Maximum Segment Size (RFC 793)
     state->ts_support = tcpMain->par("timestampSupport"); // if set, this means that current host supports TS (RFC 1323)
+    state->ecnWillingness = tcpMain->par("ecnWillingness"); // if set, current host is willing to use ECN
+    state->dupthresh = tcpMain->par("dupthresh");
     state->sack_support = tcpMain->par("sackSupport"); // if set, this means that current host supports SACK (RFC 2018, 2883, 3517)
 
     if (state->sack_support) {