From 0f396a5b3a61cbb41ab36c88dd555a30789d9f46 Mon Sep 17 00:00:00 2001
From: david <david@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Tue, 2 Oct 2007 06:58:12 +0000
Subject: [PATCH] Merge from /nmap-exp/david/nmap-massping-migration. This is
 the change that scales per-host congestion control increments in the same way
 those for the group already are. This speeds scanning in some cases
 (particularly with few hosts, when the group congestion control is not the
 limiting factor). I'm going to experiment with raising the increment cap to
 allow this to have more of an effect.

Scale host congestion control variables similarly to the way group congestion
control is scaled. For the rationale see
http://www.bamsoftware.com/wiki/Nmap/PerformanceGraphs#host-scaled.

Host cc_scale should use (numprobes_sent + numpings_sent), not (numprobes_sent + numprobes_sent).
---
 scan_engine.cc | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/scan_engine.cc b/scan_engine.cc
index eb1e0efcc..8534bc1fb 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -571,6 +571,13 @@ public:
   int numpings_sent;
   /* Boost the scan delay for this host, usually because too many packet
      drops were detected. */
+  int numprobes_replied_to; /* The number of probes for which we've received
+     responses. Used for scaling congestion control increments. */
+  /* Returns the scaling factor to use when incrementing the congestion window.
+     This is the minimum of
+     (numprobes_sent + numpings_sent) / numprobes_replied_to and
+     cc_scale_max. */
+  double cc_scale();
   void boostScanDelay();
   struct send_delay_nfo sdn;
   struct rate_limit_detection_nfo rld;
@@ -976,6 +983,7 @@ HostScanStats::HostScanStats(Target *t, UltraScanInfo *UltraSI) {
   ports_finished = 0;
   numprobes_sent = 0;
   numpings_sent = 0;
+  numprobes_replied_to = 0;
   init_ultra_timing_vals(&timing, TIMING_HOST, 1, &(USI->perf), &USI->now);
   bench_tryno = 0;
   memset(&sdn, 0, sizeof(sdn));
@@ -1837,6 +1845,7 @@ static void ultrascan_adjust_timing(UltraScanInfo *USI, HostScanStats *hss,
   USI->gstats->timing.num_updates++;
 
   USI->gstats->probes_replied_to++;
+  hss->numprobes_replied_to++;
 
   /* Adjust window */
   if (probe->tryno > 0 || !rcvdtime) {
@@ -1859,10 +1868,12 @@ static void ultrascan_adjust_timing(UltraScanInfo *USI, HostScanStats *hss,
        appropriate.  */
     if (hss->timing.cwnd < hss->timing.ccthresh) {
       /* In quick start mode */
-      hss->timing.cwnd += ping_magnifier * USI->perf.quick_incr;
+      hss->timing.cwnd += ping_magnifier * USI->perf.quick_incr * hss->cc_scale();
+      if (hss->timing.cwnd > hss->timing.ccthresh)
+	hss->timing.cwnd = hss->timing.ccthresh;
     } else {
       /* Congestion control mode */
-      hss->timing.cwnd += ping_magnifier * USI->perf.cc_incr / hss->timing.cwnd;
+      hss->timing.cwnd += ping_magnifier * USI->perf.cc_incr / hss->timing.cwnd * hss->cc_scale();
     }
     if (hss->timing.cwnd > USI->perf.max_cwnd)
       hss->timing.cwnd = USI->perf.max_cwnd;
@@ -2197,6 +2208,20 @@ static bool ultrascan_port_pspec_update(UltraScanInfo *USI,
   return oldstate != newstate;
 }
 
+/* Returns the scaling factor to use when incrementing the congestion window.
+   This is the minimum of
+   (numprobes_sent + numpings_sent) / numprobes_replied_to and cc_scale_max. */
+double HostScanStats::cc_scale() {
+  double ratio;
+
+  if (numprobes_replied_to == 0)
+    return USI->perf.cc_scale_max;
+
+  ratio = (double) (numprobes_sent + numpings_sent) / numprobes_replied_to;
+
+  return MIN(ratio, USI->perf.cc_scale_max);
+}
+
   /* Boost the scan delay for this host, usually because too many packet
      drops were detected. */
 void HostScanStats::boostScanDelay() {