HTTP/3: restricted symbols in header names. As per HTTP/3 draft 27, a request or response containing uppercase header field names MUST be treated as malformed. Also, existing rules applied when parsing HTTP/1 header names are also applied to HTTP/3 header names: - null character is not allowed - underscore character may or may not be treated as invalid depending on the value of "underscores_in_headers" - all non-alphanumeric characters with the exception of '-' are treated as invalid Also, the r->locase_header field is now filled while parsing an HTTP/3 header. Error logging for invalid headers is fixed as well.

--- a/src/http/v3/ngx_http_v3.h
+++ b/src/http/v3/ngx_http_v3.h
@@ -68,7 +68,8 @@ typedef struct {
 
 
 ngx_int_t ngx_http_v3_parse_request(ngx_http_request_t *r, ngx_buf_t *b);
-ngx_int_t ngx_http_v3_parse_header(ngx_http_request_t *r, ngx_buf_t *b);
+ngx_int_t ngx_http_v3_parse_header(ngx_http_request_t *r, ngx_buf_t *b,
+    ngx_uint_t allow_underscores);
 ngx_int_t ngx_http_v3_parse_request_body(ngx_http_request_t *r, ngx_buf_t *b,
     ngx_http_chunked_t *ctx);
 ngx_chain_t *ngx_http_v3_create_header(ngx_http_request_t *r);