http1: allow configuring format of encoded http1 response headers (#8499)

Adds a configuration option that will convert all header keys into
Proper-Case. This is useful to allow Envoy to respond with headers
that match the casing of other systems, to ensure that the wire format
of responses is unchanged when migrating to Envoy.

Fixes #8463

Signed-off-by: Snow Pettersen <snowp@squareup.com>

Mirrored from https://github.com/envoyproxy/envoy @ 7846427d7aafb9e023c38bb6e704262f7c724c92

envoy/api/v2/core/protocol.proto

@@ -39,6 +39,22 @@ message HttpProtocolOptions {
 }
 
 message Http1ProtocolOptions {
+  message HeaderKeyFormat {
+    message ProperCaseWords {
+    }
+
+    oneof header_format {
+      option (validate.required) = true;
+
+      // Formats the header by proper casing words: the first character and any character following
+      // a special character will be capitalized if it's an alpha character. For example,
+      // "content-type" becomes "Content-Type", and "foo$b#$are" becomes "Foo$B#$Are".
+      // Note that while this results in most headers following conventional casing, certain headers
+      // are not covered. For example, the "TE" header will be formatted as "Te".
+      ProperCaseWords proper_case_words = 1;
+    }
+  }
+
   // Handle HTTP requests with absolute URLs in the requests. These requests
   // are generally sent by clients to forward/explicit proxies. This allows clients to configure
   // envoy as their HTTP proxy. In Unix, for example, this is typically done by setting the
@@ -55,6 +71,12 @@ message Http1ProtocolOptions {
   // Envoy does not otherwise support HTTP/1.0 without a Host header.
   // This is a no-op if *accept_http_10* is not true.
   string default_host_for_http_10 = 3;
+
+  // Describes how the keys for response headers should be formatted. By default, all header keys
+  // are lower cased.
+  // [#not-implemented-hide:] Hiding until both request and response formatting has been
+  // implemented.
+  HeaderKeyFormat header_key_format = 4;
 }
 
 // [#next-free-field: 13]

envoy/api/v3alpha/core/protocol.proto

@@ -39,6 +39,22 @@ message HttpProtocolOptions {
 }
 
 message Http1ProtocolOptions {
+  message HeaderKeyFormat {
+    message ProperCaseWords {
+    }
+
+    oneof header_format {
+      option (validate.required) = true;
+
+      // Formats the header by proper casing words: the first character and any character following
+      // a special character will be capitalized if it's an alpha character. For example,
+      // "content-type" becomes "Content-Type", and "foo$b#$are" becomes "Foo$B#$Are".
+      // Note that while this results in most headers following conventional casing, certain headers
+      // are not covered. For example, the "TE" header will be formatted as "Te".
+      ProperCaseWords proper_case_words = 1;
+    }
+  }
+
   // Handle HTTP requests with absolute URLs in the requests. These requests
   // are generally sent by clients to forward/explicit proxies. This allows clients to configure
   // envoy as their HTTP proxy. In Unix, for example, this is typically done by setting the
@@ -55,6 +71,12 @@ message Http1ProtocolOptions {
   // Envoy does not otherwise support HTTP/1.0 without a Host header.
   // This is a no-op if *accept_http_10* is not true.
   string default_host_for_http_10 = 3;
+
+  // Describes how the keys for response headers should be formatted. By default, all header keys
+  // are lower cased.
+  // [#not-implemented-hide:] Hiding until both request and response formatting has been
+  // implemented.
+  HeaderKeyFormat header_key_format = 4;
 }
 
 // [#next-free-field: 13]