nghttpx: Allow '*' in --error-page to be used as wildcard

src/shrpx.cc

@@ -1843,12 +1843,13 @@ HTTP:
               towards this number.
               Default: )" << get_config()->http.max_response_header_fields
       << R"(
-  --error-page=<CODE>=<PATH>
+  --error-page=(<CODE>|*)=<PATH>
               Set file path  to custom error page  served when nghttpx
               originally  generates  HTTP  error status  code  <CODE>.
               <CODE> must be greater than or equal to 400, and at most
-              599.  If  error status  code comes from  backend server,
-              the custom error pages are not used.
+              599.  If "*"  is used instead of <CODE>,  it matches all
+              HTTP  status  code.  If  error  status  code comes  from
+              backend server, the custom error pages are not used.
 
 Debug:
   --frontend-http2-dump-request-header=<PATH>

src/shrpx_config.cc

@@ -715,13 +715,21 @@ int parse_error_page(std::vector<ErrorPage> &error_pages, const char *opt,
   }
 
   auto codestr = StringRef{std::begin(arg), eq};
-  auto code = util::parse_uint(codestr);
+  unsigned int code;
 
-  if (code == -1 || code < 400 || code > 599) {
+  if (codestr == "*") {
+    code = 0;
+  } else {
+    auto n = util::parse_uint(codestr);
+
+    if (n == -1 || n < 400 || n > 599) {
       LOG(ERROR) << opt << ": bad code: '" << codestr << "'";
       return -1;
     }
 
+    code = static_cast<unsigned int>(n);
+  }
+
   auto path = StringRef{eq + 1, std::end(arg)};
 
   std::vector<uint8_t> content;
@@ -748,8 +756,7 @@ int parse_error_page(std::vector<ErrorPage> &error_pages, const char *opt,
     content.insert(std::end(content), std::begin(buf), std::begin(buf) + n);
   }
 
-  error_pages.push_back(
-      ErrorPage{std::move(content), static_cast<unsigned int>(code)});
+  error_pages.push_back(ErrorPage{std::move(content), code});
 
   return 0;
 }

src/shrpx_config.h

@@ -443,6 +443,7 @@ struct TLSConfig {
 struct ErrorPage {
   // not NULL-terminated
   std::vector<uint8_t> content;
+  // 0 is special value, and it matches all HTTP status code.
   unsigned int http_status;
 };
 

src/shrpx_http.cc

@@ -40,7 +40,7 @@ StringRef create_error_html(BlockAllocator &balloc, unsigned int http_status) {
 
   const auto &error_pages = httpconf.error_pages;
   for (const auto &page : error_pages) {
-    if (page.http_status == http_status) {
+    if (page.http_status == 0 || page.http_status == http_status) {
       return StringRef{std::begin(page.content), std::end(page.content)};
     }
   }