From c80bc2efb27995d4a19537909c90e067551b2fbc Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Thu, 16 May 2024 19:31:47 +0000
Subject: [PATCH] Rate-limit capacity scale-downs to 1 per MIN_DNS_TIMEOUT

---
 nmap_dns.cc | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/nmap_dns.cc b/nmap_dns.cc
index 85a5c9072..b8728f7d0 100644
--- a/nmap_dns.cc
+++ b/nmap_dns.cc
@@ -556,7 +556,7 @@ static int deal_with_timedout_reads(bool adjust_timing) {
     if (nextI == servI->in_process.end()) continue;
 
     struct timeval earliest_sent = now;
-    bool adjusted = false;
+    bool adjusted = !adjust_timing;
     bool may_increase = adjust_timing;
     do {
       reqI = nextI++;
@@ -1195,7 +1195,7 @@ static void nmap_mass_dns_core(DNS::Request *requests, int num_requests) {
 
   std::list<request *>::iterator reqI;
   request *tpreq;
-  int timeout;
+  int timeout = 0;
   int i;
   char spmobuf[1024];
 
@@ -1280,8 +1280,16 @@ static void nmap_mass_dns_core(DNS::Request *requests, int num_requests) {
   SPM = new ScanProgressMeter(spmobuf);
   stat_actual = total_reqs;
 
+  int since_last = 0;
   while (total_reqs > 0) {
-    timeout = deal_with_timedout_reads(true);
+    since_last += timeout;
+    if (since_last > MIN_DNS_TIMEOUT) {
+      since_last = 0;
+      timeout = deal_with_timedout_reads(true);
+    }
+    else {
+      timeout = deal_with_timedout_reads(false);
+    }
 
     do_possible_writes();