From 2e127ef38eddaef53bfc95ced5c8a17798191825 Mon Sep 17 00:00:00 2001
From: Markus Makela <markus.makela@mariadb.com>
Date: Tue, 1 Dec 2015 10:11:29 +0200
Subject: [PATCH] Fix to MXS-429: Missing parameter no longer causes a crash

If a server is missing a weighting parameter the default weight will be used.
---
 server/modules/routing/readconnroute.c | 105 +++++++++++++++----------
 1 file changed, 65 insertions(+), 40 deletions(-)

diff --git a/server/modules/routing/readconnroute.c b/server/modules/routing/readconnroute.c
index 6433d768e..299e422b2 100644
--- a/server/modules/routing/readconnroute.c
+++ b/server/modules/routing/readconnroute.c
@@ -248,46 +248,71 @@ char		*weightby;
 	}
 	inst->servers[n] = NULL;
 
-	if ((weightby = serviceGetWeightingParameter(service)) != NULL)
-	{
-		int total = 0;
-		for (n = 0; inst->servers[n]; n++)
-		{
-			backend = inst->servers[n];
-			total += atoi(serverGetParameter(backend->server,
-						weightby));
-		}
-		if (total == 0)
-		{
-                    MXS_WARNING("Weighting Parameter for service '%s' "
-				"will be ignored as no servers have values "
-				"for the parameter '%s'.\n",
-				service->name, weightby);
-		}
-		else
-		{
-			for (n = 0; inst->servers[n]; n++)
-			{
-				int perc, wght;
-				backend = inst->servers[n];
-				perc = ((wght = atoi(serverGetParameter(backend->server,
-						weightby))) * 1000) / total;
-				if (perc == 0 && wght != 0)
-					perc = 1;
-				backend->weight = perc;
-				if (perc == 0)
-				{
-                                    MXS_ERROR("Server '%s' has no value "
-                                              "for weighting parameter '%s', "
-                                              "no queries will be routed to "
-                                              "this server.\n",
-                                              inst->servers[n]->server->unique_name,
-                                              weightby);
-				}
-		
-			}
-		}
-	}
+    if ((weightby = serviceGetWeightingParameter(service)) != NULL)
+    {
+        int total = 0;
+
+        for (int n = 0; inst->servers[n]; n++)
+        {
+            BACKEND *backend = inst->servers[n];
+            char *param = serverGetParameter(backend->server, weightby);
+            if (param)
+            {
+                total += atoi(param);
+            }
+        }
+        if (total == 0)
+        {
+            MXS_WARNING("Weighting Parameter for service '%s' "
+                        "will be ignored as no servers have values "
+                        "for the parameter '%s'.",
+                        service->name, weightby);
+        }
+        else if (total < 0)
+        {
+            MXS_ERROR("Sum of weighting parameter '%s' for service '%s' exceeds "
+                      "maximum value of %d. Weighting will be ignored.",
+                      weightby, service->name, INT_MAX);
+        }
+        else
+        {
+            for (int n = 0; inst->servers[n]; n++)
+            {
+                BACKEND *backend = inst->servers[n];
+                char *param = serverGetParameter(backend->server, weightby);
+                if (param)
+                {
+                    int wght = atoi(param);
+                    int perc = (wght * 1000) / total;
+
+                    if (perc == 0)
+                    {
+                        perc = 1;
+                        MXS_ERROR("Weighting parameter '%s' with a value of %d for"
+                                  " server '%s' rounds down to zero with total weight"
+                                  " of %d for service '%s'. No queries will be "
+                                  "routed to this server.", weightby, wght,
+                                  backend->server->unique_name, total,
+                                  service->name);
+                    }
+                    else if (perc < 0)
+                    {
+                        MXS_ERROR("Weighting parameter '%s' for server '%s' is too large, "
+                                  "maximum value is %d. No weighting will be used for this server.",
+                                  weightby, backend->server->unique_name, INT_MAX / 1000);
+                        perc = 1000;
+                    }
+                    backend->weight = perc;
+                }
+                else
+                {
+                    MXS_WARNING("Server '%s' has no parameter '%s' used for weighting"
+                                " for service '%s'.", backend->server->unique_name,
+                                weightby, service->name);
+                }
+            }
+        }
+    }
 
 	/*
 	 * Process the options