Upstream: early hints support.

The change implements processing upstream early hints response in
ngx_http_proxy_module and ngx_http_grpc_module.  A new directive
"early_hints" enables sending early hints to the client.  By default,
sending early hints is disabled.

Example:

    map $http_sec_fetch_mode $early_hints {
        navigate $http2$http3;
    }

    early_hints $early_hints;

    proxy_pass http://example.com;

1 files changed, 7 insertions, 1 deletions

diff --git a/src/http/modules/ngx_http_grpc_module.c b/src/http/modules/ngx_http_grpc_module.c
index 80046d6a4..d74b17708 100644
--- a/src/http/modules/ngx_http_grpc_module.c
+++ b/src/http/modules/ngx_http_grpc_module.c
@@ -1869,7 +1869,8 @@ ngx_http_grpc_process_header(ngx_http_request_t *r)
                         return NGX_HTTP_UPSTREAM_INVALID_HEADER;
                     }
 
-                    if (status < NGX_HTTP_OK) {
+                    if (status < NGX_HTTP_OK && status != NGX_HTTP_EARLY_HINTS)
+                    {
                         ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                       "upstream sent unexpected :status \"%V\"",
                                       status_line);
@@ -1902,6 +1903,10 @@ ngx_http_grpc_process_header(ngx_http_request_t *r)
                 h->lowcase_key = h->key.data;
                 h->hash = ngx_hash_key(h->key.data, h->key.len);
 
+                if (u->headers_in.status_n == NGX_HTTP_EARLY_HINTS) {
+                    continue;
+                }
+
                 hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,
                                    h->lowcase_key, h->key.len);
 
@@ -4413,6 +4418,7 @@ ngx_http_grpc_create_loc_conf(ngx_conf_t *cf)
     conf->upstream.pass_request_body = 1;
     conf->upstream.force_ranges = 0;
     conf->upstream.pass_trailers = 1;
+    conf->upstream.pass_early_hints = 1;
     conf->upstream.preserve_output = 1;
 
     conf->headers_source = NGX_CONF_UNSET_PTR;