fix segmentation fault for via-routes with invalid intermediate segments

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 5.3.3
+  Changes from 5.3.2
+    - Bugfixes
+      - Fixed an issue that would result in segfaults for viaroutes with an invalid intermediate segment when u-turns were allowed at the via-location
+
 # 5.3.2
   Changes from 5.3.1
     - Bugfixes

features/testbot/via.feature

@@ -262,3 +262,35 @@ Feature: Via points
             | 3,2,1     | ab,bc,cd,da,ab,ab,ab,bc,cd,da,ab,ab | 3000m +-1    |
             | 6,5,4     | bc,cd,da,ab,bc,bc,bc,cd,da,ab,bc,bc | 3000m +-1    |
             | 9,8,7     | cd,da,ab,bc,cd,cd,cd,da,ab,bc,cd,cd | 3000m +-1    |
+
+    # See issue #2706
+    Scenario: Incorrect ordering of nodes can produce multiple U-turns
+        Given the node map
+            |   | a |   |   |   |
+            | e | b | c | d | f |
+
+        And the ways
+            | nodes  | oneway |
+            | abcd   | no     |
+            | ebbdcf | yes    |
+
+        When I route I should get
+            | from | to | route         |
+            | e    | f  | ebbdcf,ebbdcf |
+
+    @2798
+    Scenario: UTurns Enabled
+        Given the node map
+            | a | b | c | d | e |
+
+        And the query options
+            | continue_straight | false |
+
+        And the ways
+            | nodes | oneway |
+            | abc   | yes    |
+            | edc   | yes    |
+
+        When I route I should get
+            | waypoints | route |
+            | a,b,e     |       |

include/engine/routing_algorithms/shortest_path.hpp

@@ -114,7 +114,11 @@ class ShortestPathRouting final
                           needs_loop_forwad,
                           needs_loop_backwards);
         }
-        new_total_distance += std::min(total_distance_to_forward, total_distance_to_reverse);
+        // if no route is found between two parts of the via-route, the entire route becomes
+        // invalid. Adding to invalid edge weight sadly doesn't return an invalid edge weight. Here
+        // we prevent the possible overflow, faking the addition of infinity + x == infinity
+        if (new_total_distance != INVALID_EDGE_WEIGHT)
+            new_total_distance += std::min(total_distance_to_forward, total_distance_to_reverse);
     }
 
     // searches shortest path between: