nghttpx: Parse te header field a bit more properly

src/http2.cc

@@ -1665,6 +1665,31 @@ StringRef copy_lower(BlockAllocator &balloc, const StringRef &src) {
   return StringRef{iov.base, p};
 }
 
+bool contains_trailers(const StringRef &s) {
+  constexpr auto trailers = StringRef::from_lit("trailers");
+
+  for (auto p = std::begin(s), end = std::end(s);; ++p) {
+    p = std::find_if(p, end, [](char c) { return c != ' ' && c != '\t'; });
+    if (p == end || end - p < trailers.size()) {
+      return false;
+    }
+    if (util::strieq(trailers, StringRef{p, p + trailers.size()})) {
+      // Make sure that there is no character other than white spaces
+      // before next "," or end of string.
+      p = std::find_if(p + trailers.size(), end,
+                       [](char c) { return c != ' ' && c != '\t'; });
+      if (p == end || *p == ',') {
+        return true;
+      }
+    }
+    // Skip to next ",".
+    p = std::find_if(p, end, [](char c) { return c == ','; });
+    if (p == end) {
+      return false;
+    }
+  }
+}
+
 } // namespace http2
 
 } // namespace nghttp2

src/http2.h

@@ -384,6 +384,9 @@ int construct_push_component(BlockAllocator &balloc, StringRef &scheme,
 // Copies |src| and return its lower-cased version.
 StringRef copy_lower(BlockAllocator &balloc, const StringRef &src);
 
+// Returns true if te header field value |s| contains "trailers".
+bool contains_trailers(const StringRef &s);
+
 } // namespace http2
 
 } // namespace nghttp2

src/http2_test.cc

@@ -962,4 +962,20 @@ void test_http2_construct_push_component(void) {
   CU_ASSERT("/b/?q=a" == path);
 }
 
+void test_http2_contains_trailers(void) {
+  CU_ASSERT(!http2::contains_trailers(StringRef::from_lit("")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("trailers")));
+  // Match must be case-insensitive.
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("TRAILERS")));
+  CU_ASSERT(!http2::contains_trailers(StringRef::from_lit("trailer")));
+  CU_ASSERT(!http2::contains_trailers(StringRef::from_lit("trailers  3")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("trailers,")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("trailers,foo")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("foo,trailers")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit("foo,trailers,bar")));
+  CU_ASSERT(
+      http2::contains_trailers(StringRef::from_lit("foo, trailers ,bar")));
+  CU_ASSERT(http2::contains_trailers(StringRef::from_lit(",trailers")));
+}
+
 } // namespace shrpx

src/http2_test.h

@@ -46,6 +46,7 @@ void test_http2_normalize_path(void);
 void test_http2_rewrite_clean_path(void);
 void test_http2_get_pure_path_component(void);
 void test_http2_construct_push_component(void);
+void test_http2_contains_trailers(void);
 
 } // namespace shrpx
 

src/shrpx-unittest.cc

@@ -102,6 +102,8 @@ int main(int argc, char *argv[]) {
                    shrpx::test_http2_get_pure_path_component) ||
       !CU_add_test(pSuite, "http2_construct_push_component",
                    shrpx::test_http2_construct_push_component) ||
+      !CU_add_test(pSuite, "http2_contains_trailers",
+                   shrpx::test_http2_contains_trailers) ||
       !CU_add_test(pSuite, "downstream_field_store_append_last_header",
                    shrpx::test_downstream_field_store_append_last_header) ||
       !CU_add_test(pSuite, "downstream_field_store_header",

src/shrpx_http2_downstream_connection.cc

@@ -402,7 +402,7 @@ int Http2DownstreamConnection::push_request_headers() {
   // HTTP/1 upstream request can contain keyword other than
   // "trailers".  We just forward "trailers".
   // TODO more strict handling required here.
-  if (te && util::strifind(te->value, StringRef::from_lit("trailers"))) {
+  if (te && http2::contains_trailers(te->value)) {
     nva.push_back(http2::make_nv_ll("te", "trailers"));
   }