nghttpx: Fix the bug that forwarded query contains duplicated '?'

This change also fixes that bug that the multiple '/' at the start of
request were not coalesced into one.

src/http2.cc

@@ -1550,6 +1550,8 @@ StringRef path_join(BlockAllocator &balloc, const StringRef &base_path,
   if (rel_path[0] == '/') {
     *p++ = '/';
     ++first;
+    for (; first != last && *first == '/'; ++first)
+      ;
   } else if (base_path.empty()) {
     *p++ = '/';
   } else {
@@ -1657,11 +1659,12 @@ StringRef rewrite_clean_path(BlockAllocator &balloc, const StringRef &src) {
   }
   // probably, not necessary most of the case, but just in case.
   auto fragment = std::find(std::begin(src), std::end(src), '#');
-  auto query = std::find(std::begin(src), fragment, '?');
+  auto raw_query = std::find(std::begin(src), fragment, '?');
+  auto query = raw_query;
   if (query != fragment) {
     ++query;
   }
-  return normalize_path(balloc, StringRef{std::begin(src), query},
+  return normalize_path(balloc, StringRef{std::begin(src), raw_query},
                         StringRef{query, fragment});
 }
 

src/http2_test.cc

@@ -817,6 +817,15 @@ void test_http2_path_join(void) {
     auto rel = StringRef{};
     CU_ASSERT("/?r" == http2::path_join(base, baseq, rel, StringRef{}));
   }
+  {
+    // path starts with multiple '/'s.
+    auto base = StringRef{};
+    auto baseq = StringRef{};
+    auto rel = StringRef::from_lit("//alpha//bravo");
+    auto relq = StringRef::from_lit("charlie");
+    CU_ASSERT("/alpha/bravo?charlie" ==
+              http2::path_join(base, baseq, rel, relq));
+  }
 }
 
 void test_http2_normalize_path(void) {
@@ -870,6 +879,10 @@ void test_http2_rewrite_clean_path(void) {
             http2::rewrite_clean_path(balloc, StringRef::from_lit("alpha%3a")));
 
   CU_ASSERT("" == http2::rewrite_clean_path(balloc, StringRef{}));
+
+  CU_ASSERT(
+      "/alpha?bravo" ==
+      http2::rewrite_clean_path(balloc, StringRef::from_lit("//alpha?bravo")));
 }
 
 void test_http2_get_pure_path_component(void) {