[nginx] HTTP/2: invalid connection preface logging (ticket #1981).

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/7114d21bc2b1
branches:  
changeset: 7656:7114d21bc2b1
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Mon May 25 18:33:42 2020 +0300
description:
HTTP/2: invalid connection preface logging (ticket #1981).

Previously, invalid connection preface errors were only logged at debug
level, providing no visible feedback, in particular, when a plain text
HTTP/2 listening socket is erroneously used for HTTP/1.x connections.
Now these are explicitly logged at the info level, much like other
client-related errors.

diffstat:

 src/http/v2/ngx_http_v2.c |  10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diffs (27 lines):

diff -r bd4d1b9db0ee -r 7114d21bc2b1 src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c	Sat May 23 15:53:08 2020 +0300
+++ b/src/http/v2/ngx_http_v2.c	Mon May 25 18:33:42 2020 +0300
@@ -731,9 +731,8 @@ ngx_http_v2_state_preface(ngx_http_v2_co
     }
 
     if (ngx_memcmp(pos, preface, sizeof(preface) - 1) != 0) {
-        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
-                       "invalid http2 connection preface \"%*s\"",
-                       sizeof(preface) - 1, pos);
+        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
+                      "invalid connection preface");
 
         return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_PROTOCOL_ERROR);
     }
@@ -754,9 +753,8 @@ ngx_http_v2_state_preface_end(ngx_http_v
     }
 
     if (ngx_memcmp(pos, preface, sizeof(preface) - 1) != 0) {
-        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
-                       "invalid http2 connection preface \"%*s\"",
-                       sizeof(preface) - 1, pos);
+        ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
+                      "invalid connection preface");
 
         return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_PROTOCOL_ERROR);
     }