nghttpx: Deal with the path without trailing slash on pattern match

If pattern ends with '/', and pattern and path matches without that
slash, we consider they match to deal with request to the directory
without trailing slash.  That is if pattern is "/foo/" and path is
"/foo", we consider they match.

src/shrpx.cc

@@ -1003,37 +1003,55 @@ Connections:
               addresses are  accepted by repeating this  option.  UNIX
               domain socket  can be  specified by prefixing  path name
               with "unix:" (e.g., unix:/var/run/backend.sock).
+
               Optionally, if <PATTERN>s are given, the backend address
               is only used if request matches the pattern.  If -s, -p,
               --client  or  --http2-bridge  is  used,  <PATTERN>s  are
               ignored.  The  pattern matching  is closely  designed to
               ServeMux in net/http package of Go programming language.
-              <PATTERN> consists  of path, host  + path or  host.  The
-              path  must starts  with "/".   If it  ends with  "/", it
+              <PATTERN> consists  of path, host  + path or  just host.
+              The path must starts with "/".   If it ends with "/", it
               matches to  the request path  whose prefix is  the path.
-              If it  does not  end with "/",  it performs  exact match
-              against the request path.  If host is given, it performs
-              exact match against the request  host.  If host alone is
-              given, "/"  is appended  to it, so  that it  matches all
-              paths  under the  host  (e.g., specifying  "nghttp2.org"
-              equals   to  "nghttp2.org/").    Longer  patterns   take
-              precedence  over shorter  ones,  breaking a  tie by  the
-              order  of  the  appearance  in  the  configuration.   If
-              <PATTERN>  is omitted,  "/"  is used  as pattern,  which
-              matches  all paths  (catch-all  pattern).  For  example,
-              -b'127.0.0.1,8080;nghttp2.org/httpbin/'    matches   the
-              request   host  "nghttp2.org"   and  the   request  path
-              "/httpbin/get",  but does  not  match  the request  host
-              "nghttp2.org" and  the request path  "/index.html".  The
-              multiple <PATTERN>s can be specified, delimiting them by
-              ":".                                          Specifying
+              To  deal  with  the  request to  the  directory  without
+              trailing slash, pattern which ends with "/" also matches
+              the path if pattern == path + "/" (e.g., pattern "/foo/"
+              matches path "/foo").   If it does not end  with "/", it
+              performs exact match against  the request path.  If host
+              is given,  it performs  exact match against  the request
+              host.  If host alone is given, "/" is appended to it, so
+              that  it  matches  all   paths  under  the  host  (e.g.,
+              specifying "nghttp2.org" equals to "nghttp2.org/").
+
+              Longer  patterns  take  precedence  over  shorter  ones,
+              breaking a  tie by  the order of  the appearance  in the
+              configuration.
+
+              If <PATTERN> is  omitted, "/" is used  as pattern, which
+              matches  all paths  (catch-all pattern).   The catch-all
+              backend must be given.
+
+              When doing  a match, nghttpx made  some normalization to
+              pattern, request host and path.  For host part, they are
+              converted to lower case.  For path part, percent-encoded
+              unreserved characters  defined in RFC 3986  are decoded,
+              and any  dot-segments (".."  and ".")   are resolved and
+              removed.
+
+              For   example,   -b'127.0.0.1,8080;nghttp2.org/httpbin/'
+              matches the  request host "nghttp2.org" and  the request
+              path "/httpbin/get", but does not match the request host
+              "nghttp2.org" and the request path "/index.html".
+
+              The  multiple <PATTERN>s  can  be specified,  delimiting
+              them            by           ":".             Specifying
               -b'127.0.0.1,8080;nghttp2.org:www.nghttp2.org'  has  the
               same  effect  to specify  -b'127.0.0.1,8080;nghttp2.org'
-              and  -b'127.0.0.1,8080:www.nghttp2.org'.    The  backend
-              addresses  sharing same  <PATTERN> are  grouped together
-              forming  load balancing  group.  Since  ";" and  ":" are
-              used  as delimiter,  <PATTERN>  must  not contain  these
-              characters.
+              and -b'127.0.0.1,8080:www.nghttp2.org'.
+
+              The backend addresses sharing same <PATTERN> are grouped
+              together forming  load balancing  group.  Since  ";" and
+              ":" are  used as  delimiter, <PATTERN> must  not contain
+              these characters.
               Default: )" << DEFAULT_DOWNSTREAM_HOST << ","
       << DEFAULT_DOWNSTREAM_PORT << R"(
   -f, --frontend=<HOST>,<PORT>

src/shrpx_config.cc

@@ -1402,7 +1402,17 @@ bool path_match(const std::string &pattern, const std::string &path) {
   if (pattern.back() != '/') {
     return pattern == path;
   }
-  return util::startsWith(path, pattern);
+
+  if (util::startsWith(path, pattern)) {
+    return true;
+  }
+
+  // If pattern ends with '/', and pattern and path matches without
+  // that slash, we consider they match to deal with request to the
+  // directory without trailing slash.  That is if pattern is "/foo/"
+  // and path is "/foo", we consider they match.
+  return util::streq(std::begin(path), path.size(), std::begin(pattern),
+                     pattern.size() - 1);
 }
 } // namespace
 

src/shrpx_config_test.cc

@@ -192,6 +192,13 @@ void test_shrpx_config_match_downstream_addr_group(void) {
   CU_ASSERT(4 == match_downstream_addr_group("WWW.nghttp2.org", "/alpha",
                                              groups, 255));
 
+  CU_ASSERT(1 == match_downstream_addr_group("nghttp2.org", "/alpha/bravo/",
+                                             groups, 255));
+
+  // /alpha/bravo also matches /alpha/bravo/
+  CU_ASSERT(1 == match_downstream_addr_group("nghttp2.org", "/alpha/bravo",
+                                             groups, 255));
+
   // path part is case-sensitive
   CU_ASSERT(0 == match_downstream_addr_group("nghttp2.org", "/Alpha/bravo",
                                              groups, 255));