HTTP parser: allowing underscore in header field names.

src/nxt_http_parse.c

@@ -509,7 +509,7 @@ nxt_http_parse_field_name(nxt_http_request_parse_t *rp, u_char **pos,
         "\0\0\0\0\0\0\0\0\0\0\0\0\0-\0\0" "0123456789\0\0\0\0\0\0"
 
         /* These 64 bytes should reside in one cache line. */
-        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0\0"
+        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0_"
         "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0\0"
 
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"

src/test/nxt_http_parse_test.c

@@ -242,7 +242,7 @@ static nxt_http_parse_test_case_t  nxt_http_test_cases[] = {
     {
         nxt_string("GET / HTTP/1.1\r\n"
                    "Ho_st: example.com\r\n\r\n"),
-        NXT_ERROR,
+        NXT_DONE,
         NULL, { NULL }
     },
     {