fix(router): host matches should be case insensitive as per RFC 3986

changelog/unreleased/kong/fix-router-host-case-insensitive.yml

@@ -0,0 +1,3 @@
+message: "Fixed an issue where the Host header was case-sensitive on route for matching, which should be case-insensitive as per RFC 3986."
+type: breaking_change
+scope: Core

kong/router/atc.lua

@@ -17,6 +17,7 @@ local pairs = pairs
 local ipairs = ipairs
 local next = next
 local max = math.max
+local lower = string.lower
 
 
 local ngx           = ngx
@@ -445,6 +446,7 @@ function _M:exec(ctx)
 
   local req_uri = ctx and ctx.request_uri or var.request_uri
   local req_host = get_header("host", ctx)
+  req_host = req_host and lower(req_host) or nil
 
   req_uri = strip_uri_args(req_uri)
 

kong/router/traditional.lua

@@ -355,8 +355,8 @@ local function marshall_route(r)
       else
         -- plain host matching
         has_host_plain = true
-        append(hosts_t, { value = host })
-        hosts_t[host] = host
+        append(hosts_t, { value = lower(host) })
+        hosts_t[lower(host)] = host
       end
     end
 
@@ -1648,7 +1648,7 @@ function _M.new(routes, cache, cache_neg)
       elseif match_wildcard_hosts then
         for i = 1, wildcard_hosts[0] do
           local host = wildcard_hosts[i]
-          local from, _, err = re_find(host_with_port, host.regex, "ajo")
+          local from, _, err = re_find(host_with_port, host.regex, "ajoi")
           if err then
             log(ERR, "could not match wildcard host: ", err)
             return
@@ -1759,6 +1759,8 @@ function _M.new(routes, cache, cache_neg)
       local req_scheme = ctx and ctx.scheme or var.scheme
       local sni = server_name()
 
+      req_host = req_host and lower(req_host) or nil
+
       local headers
       if match_headers then
         local err

kong/router/transform.lua

@@ -15,6 +15,7 @@ local ipairs = ipairs
 local tb_insert = table.insert
 local fmt = string.format
 local byte = string.byte
+local lower = string.lower
 local bor, band, lshift, rshift = bit.bor, bit.band, bit.lshift, bit.rshift
 
 
@@ -401,7 +402,7 @@ local function get_expression(route)
         host = host:sub(1, -2)
       end
 
-      local exp = "http.host ".. op .. [[ r#"]] .. host .. [["#]]
+      local exp = "http.host ".. op .. [[ r#"]] .. lower(host) .. [["#]]
       if port then
         exp = "(" .. exp .. LOGICAL_AND ..
               "net.dst.port ".. OP_EQUAL .. " " .. port .. ")"

spec/01-unit/08-router_spec.lua

@@ -163,7 +163,8 @@ for _, flavor in ipairs({ "traditional", "traditional_compatible", "expressions"
               id = "e8fb37f1-102d-461e-9c51-6608a6bb8101",
               hosts = {
                 "domain-1.org",
-                "domain-2.org"
+                "domain-2.org",
+                "Domain-Capitalized.org"
               },
             },
           },
@@ -385,6 +386,19 @@ for _, flavor in ipairs({ "traditional", "traditional_compatible", "expressions"
         assert.same(nil, match_t.matches.uri_captures)
       end)
 
+      it("[host] matches should be case insensitive", function()
+        -- host
+        local match_t = router:select("GET", "/", "domain-capitalized.org")
+        assert.truthy(match_t)
+        assert.same(use_case[1].route, match_t.route)
+        if flavor == "traditional" then
+          assert.same(use_case[1].route.hosts[3], match_t.matches.host)
+        end
+        assert.same(nil, match_t.matches.method)
+        assert.same(nil, match_t.matches.uri)
+        assert.same(nil, match_t.matches.uri_captures)
+      end)
+
       it("[host] ignores default port", function()
         -- host
         local match_t = router:select("GET", "/", "domain-1.org:80")