From: Štěpán Balážik <stepan.balazik@nic.cz>
Date: Fri, 4 Sep 2020 14:50:26 +0000 (+0200)
Subject: selection: don't include servers over error limit in selection
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f815b6785ecda13235cc00d6d77cdd9de856d13;p=thirdparty%2Fknot-resolver.git

selection: don't include servers over error limit in selection
---

diff --git a/lib/selection.c b/lib/selection.c
index c22de5ad6..4d94c4b2f 100644
--- a/lib/selection.c
+++ b/lib/selection.c
@@ -178,8 +178,6 @@ void shuffle_choices(struct choice choices[], int choices_len) {
 	}
 }
 
-#define ERROR_LIMIT 2
-
 // Performs the actual selection (currently epsilon-greedy with epsilon = 0.05).
 struct kr_transport *choose_transport(struct choice choices[],
 											 int choices_len,
@@ -211,11 +209,7 @@ struct kr_transport *choose_transport(struct choice choices[],
 		// EXPLOIT
 		shuffle_choices(choices, choices_len);
 		qsort(choices, choices_len, sizeof(struct choice), cmp_choices);
-		if (choices[0].address_state->error_count > ERROR_LIMIT) {
-			return NULL;
-		} else {
-			choice = 0;
-		}
+		choice = 0;
 	}
 
 	unsigned timeout = calc_timeout(choices[choice].address_state->rtt_state);
diff --git a/lib/selection.h b/lib/selection.h
index 24e6deda8..f46f0d7a6 100644
--- a/lib/selection.h
+++ b/lib/selection.h
@@ -11,6 +11,8 @@
 
 #include "lib/cache/api.h"
 
+#define ERROR_LIMIT_PER_SERVER 2
+
 /**
  * These errors are to be reported as feedback to server selection.
  * See `kr_server_selection::error` for more details.
diff --git a/lib/selection_forward.c b/lib/selection_forward.c
index 27bb1a490..8ca1fcece 100644
--- a/lib/selection_forward.c
+++ b/lib/selection_forward.c
@@ -55,7 +55,7 @@ void forward_choose_transport(struct kr_query *qry, struct kr_transport **transp
 		check_tcp_connections(addr_state, qry->request, &address->ip);
 		check_network_settings(addr_state, addr_len, qry->flags.NO_IPV4, qry->flags.NO_IPV6);
 
-		if(addr_state->generation == -1) {
+		if(addr_state->generation == -1 || addr_state->error_count >= ERROR_LIMIT_PER_SERVER) {
 			continue;
 		}
 		addr_state->forward_index = i;
diff --git a/lib/selection_iter.c b/lib/selection_iter.c
index 59e17f5c8..6fee28c8f 100644
--- a/lib/selection_iter.c
+++ b/lib/selection_iter.c
@@ -163,7 +163,8 @@ void iter_choose_transport(struct kr_query *qry, struct kr_transport **transport
 		size_t address_len;
 		uint8_t* address = (uint8_t *)trie_it_key(it, &address_len);
 		struct address_state *address_state = (struct address_state *)*trie_it_val(it);
-		if (address_state->generation == local_state->generation) {
+		if (address_state->generation == local_state->generation &&
+		    address_state->error_count < ERROR_LIMIT_PER_SERVER) {
 			choices[valid_addresses] = (struct choice){
 				.address = address,
 				.address_len = address_len,