From f64109d79a5b12f9fcb48e74d5c1740396539956 Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Thu, 15 Jun 2017 08:31:47 -0700
Subject: [PATCH] Fix basic_fields insert ordering

---
 CHANGELOG.md                       |  1 +
 include/beast/http/impl/fields.ipp | 28 ++++++++++++----------------
 test/http/fields.cpp               | 20 ++++++++++++++++++++
 3 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a98f23b6..e5219f99 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ Version 58:
 * Reorganize examples
 * Specification for http read
 * Avoid `std::string` in websocket
+* Fix basic_fields insert ordering
 
 API Changes:
 
diff --git a/include/beast/http/impl/fields.ipp b/include/beast/http/impl/fields.ipp
index 7c5467a7..bde28110 100644
--- a/include/beast/http/impl/fields.ipp
+++ b/include/beast/http/impl/fields.ipp
@@ -480,29 +480,25 @@ insert(field name,
         name, sname, value.str());
     auto const before =
         set_.upper_bound(sname, key_compare{});
-    if(before == set_.end())
-    {
-        set_.push_back(e);
-        list_.push_back(e);
-        return;
-    }
     if(before == set_.begin())
     {
-        set_.push_front(e);
-        list_.push_back(e);
-        return;
-    }
-    auto const last = std::prev(before);
-    if(! beast::detail::ci_equal(
-        sname, last->name_string()))
-    {
+        BOOST_ASSERT(count(sname) == 0);
         set_.insert_before(before, e);
         list_.push_back(e);
         return;
     }
-    // count(name_string) > 0
+    auto const last = std::prev(before);
+    // VFALCO is it worth comparing `field name` first?
+    if(! beast::detail::ci_equal(sname, last->name_string()))
+    {
+        BOOST_ASSERT(count(sname) == 0);
+        set_.insert_before(before, e);
+        list_.push_back(e);
+        return;
+    }
+    // keep duplicate fields together in the list
     set_.insert_before(before, e);
-    list_.insert(list_.iterator_to(*before), e);
+    list_.insert(++list_.iterator_to(*last), e);
 }
 
 template<class Allocator>
diff --git a/test/http/fields.cpp b/test/http/fields.cpp
index 5e009400..d7f2c0e7 100644
--- a/test/http/fields.cpp
+++ b/test/http/fields.cpp
@@ -375,6 +375,26 @@ public:
             BEAST_EXPECT(std::next(f.begin(), 0)->name_string() == "a");
             BEAST_EXPECT(std::next(f.begin(), 1)->name_string() == "b");
         }
+        {
+            // verify insertion orde
+            fields f;
+            f.insert( "a", 1);
+            f.insert("dd", 2);
+            f.insert("b",  3);
+            f.insert("dD", 4);
+            f.insert("c",  5);
+            f.insert("Dd", 6);
+            f.insert("DD", 7);
+            f.insert( "e", 8);
+            BEAST_EXPECT(f.count("dd") == 4);
+            BEAST_EXPECT(std::next(f.begin(), 1)->name_string() == "dd");
+            BEAST_EXPECT(std::next(f.begin(), 2)->name_string() == "dD");
+            BEAST_EXPECT(std::next(f.begin(), 3)->name_string() == "Dd");
+            BEAST_EXPECT(std::next(f.begin(), 4)->name_string() == "DD");
+            f.set("dd", "-");
+            BEAST_EXPECT(f.count("dd") == 1);
+            BEAST_EXPECT(f["dd"] == "-");
+        }
     }
 
     void run() override