src: Don't push if Link header field includes nopush

src/http2.cc

@@ -864,6 +864,29 @@ bool check_link_param_empty(const char *first, const char *last,
 }
 } // namespace
 
+namespace {
+// Returns true if link-param consists of only parmname, and it
+// matches string [pat, pat + patlen).
+bool check_link_param_without_value(const char *first, const char *last,
+                                    const char *pat, size_t patlen) {
+  if (first + patlen > last) {
+    return false;
+  }
+
+  if (first + patlen == last) {
+    return std::equal(pat, pat + patlen, first, util::CaseCmp());
+  }
+
+  switch (*(first + patlen)) {
+  case ';':
+  case ',':
+    return std::equal(pat, pat + patlen, first, util::CaseCmp());
+  }
+
+  return false;
+}
+} // namespace
+
 namespace {
 std::pair<LinkHeader, const char *>
 parse_next_link_header_once(const char *first, const char *last) {
@@ -900,6 +923,7 @@ parse_next_link_header_once(const char *first, const char *last) {
     }
     // we expect link-param
 
+    if (!ign) {
       // rel can take several relations using quoted form.
       static constexpr char PLP[] = "rel=\"";
       static constexpr size_t PLPLEN = sizeof(PLP) - 1;
@@ -995,6 +1019,15 @@ parse_next_link_header_once(const char *first, const char *last) {
         ign = true;
       }
 
+      // reject URI if we have nopush attribute.
+      static constexpr char NOPUSH[] = "nopush";
+      static constexpr size_t NOPUSHLEN = str_size(NOPUSH);
+      if (!ign &&
+          check_link_param_without_value(first, last, NOPUSH, NOPUSHLEN)) {
+        ign = true;
+      }
+    }
+
     auto param_first = first;
     for (; first != last;) {
       if (util::in_attr_char(*first)) {

src/http2_test.cc

@@ -625,6 +625,38 @@ void test_http2_parse_link_header(void) {
     CU_ASSERT(std::make_pair(&s[36], &s[39]) == res[0].uri);
     CU_ASSERT(std::make_pair(&s[42 + 14], &s[42 + 17]) == res[1].uri);
   }
+  {
+    // nopush at the end of input
+    constexpr char s[] = "<url>; rel=preload; nopush";
+    auto res = http2::parse_link_header(s, str_size(s));
+    CU_ASSERT(0 == res.size());
+  }
+  {
+    // nopush followed by ';'
+    constexpr char s[] = "<url>; rel=preload; nopush; foo";
+    auto res = http2::parse_link_header(s, str_size(s));
+    CU_ASSERT(0 == res.size());
+  }
+  {
+    // nopush followed by ','
+    constexpr char s[] = "<url>; nopush; rel=preload";
+    auto res = http2::parse_link_header(s, str_size(s));
+    CU_ASSERT(0 == res.size());
+  }
+  {
+    // string whose prefix is nopush
+    constexpr char s[] = "<url>; nopushyes; rel=preload";
+    auto res = http2::parse_link_header(s, str_size(s));
+    CU_ASSERT(1 == res.size());
+    CU_ASSERT(std::make_pair(&s[1], &s[4]) == res[0].uri);
+  }
+  {
+    // rel=preload twice
+    constexpr char s[] = "<url>; rel=preload; rel=preload";
+    auto res = http2::parse_link_header(s, str_size(s));
+    CU_ASSERT(1 == res.size());
+    CU_ASSERT(std::make_pair(&s[1], &s[4]) == res[0].uri);
+  }
 }
 
 void test_http2_path_join(void) {