From d538b9d97f80d7ad86d982deca44172a7b7f8c94 Mon Sep 17 00:00:00 2001
From: Vsevolod Stakhov <vsevolod@highsecure.ru>
Date: Tue, 10 Dec 2019 10:49:22 +0000
Subject: [PATCH] [Fix] Select a different upstream on last retransmit

Issue: #3182
---
 src/rspamd_proxy.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/rspamd_proxy.c b/src/rspamd_proxy.c
index 6cc2e592d..2a0cadbf1 100644
--- a/src/rspamd_proxy.c
+++ b/src/rspamd_proxy.c
@@ -1872,8 +1872,25 @@ retry:
 			goto err;
 		}
 
-		session->master_conn->up = rspamd_upstream_get (backend->u,
-				RSPAMD_UPSTREAM_ROUND_ROBIN, NULL, 0);
+		/* Provide hash key if hashing based on source address is desired */
+		guint hash_len;
+		gpointer hash_key = rspamd_inet_address_get_hash_key (session->client_addr,
+				&hash_len);
+
+		if (session->ctx->max_retries > 1 &&
+			session->retries == session->ctx->max_retries) {
+
+			session->master_conn->up = rspamd_upstream_get_except (backend->u,
+					session->master_conn->up,
+					RSPAMD_UPSTREAM_ROUND_ROBIN,
+					hash_key, hash_len);
+		}
+		else {
+			session->master_conn->up = rspamd_upstream_get (backend->u,
+					RSPAMD_UPSTREAM_ROUND_ROBIN,
+					hash_key, hash_len);
+		}
+
 		session->master_conn->timeout = backend->timeout;
 
 		if (session->master_conn->up == NULL) {