Upstream: fixed passwords support for dynamic certificates.

Passwords were not preserved in optimized SSL contexts, the bug had
appeared in d791b4aab (1.23.1), as in the following configuration:

    server {
        proxy_ssl_password_file password;
        proxy_ssl_certificate $ssl_server_name.crt;
        proxy_ssl_certificate_key $ssl_server_name.key;

        location /original/ {
            proxy_pass https://u1/;
        }

        location /optimized/ {
            proxy_pass https://u2/;
        }
    }

The fix is to always preserve passwords, by copying to the configuration
pool, if dynamic certificates are used.  This is done as part of merging
"ssl_passwords" configuration.

To minimize the number of copies, a preserved version is then used for
inheritance.  A notable exception is inheritance of preserved empty
passwords to the context with statically configured certificates:

    server {
        proxy_ssl_certificate $ssl_server_name.crt;
        proxy_ssl_certificate_key $ssl_server_name.key;

        location / {
            proxy_pass ...;

            proxy_ssl_certificate example.com.crt;
            proxy_ssl_certificate_key example.com.key;
        }
    }

In this case, an unmodified version (NULL) of empty passwords is set,
to allow reading them from the password prompt on nginx startup.

As an additional optimization, a preserved instance of inherited
configured passwords is set to the previous level, to inherit it
to other contexts:

    server {
        proxy_ssl_password_file password;

        location /1/ {
            proxy_pass https://u1/;
            proxy_ssl_certificate $ssl_server_name.crt;
            proxy_ssl_certificate_key $ssl_server_name.key;
        }

        location /2/ {
            proxy_pass https://u2/;
            proxy_ssl_certificate $ssl_server_name.crt;
            proxy_ssl_certificate_key $ssl_server_name.key;
        }
    }

1 files changed, 9 insertions, 11 deletions

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index 27c34fef2..d4c5abf62 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -3976,8 +3976,13 @@ ngx_http_proxy_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
                               prev->upstream.ssl_certificate_key, NULL);
     ngx_conf_merge_ptr_value(conf->upstream.ssl_certificate_cache,
                               prev->upstream.ssl_certificate_cache, NULL);
-    ngx_conf_merge_ptr_value(conf->upstream.ssl_passwords,
-                              prev->upstream.ssl_passwords, NULL);
+
+    if (ngx_http_upstream_merge_ssl_passwords(cf, &conf->upstream,
+                                              &prev->upstream)
+        != NGX_OK)
+    {
+        return NGX_CONF_ERROR;
+    }
 
     ngx_conf_merge_ptr_value(conf->ssl_conf_commands,
                               prev->ssl_conf_commands, NULL);
@@ -5337,16 +5342,9 @@ ngx_http_proxy_set_ssl(ngx_conf_t *cf, ngx_http_proxy_loc_conf_t *plcf)
             return NGX_ERROR;
         }
 
-        if (plcf->upstream.ssl_certificate->lengths
-            || plcf->upstream.ssl_certificate_key->lengths)
+        if (plcf->upstream.ssl_certificate->lengths == NULL
+            && plcf->upstream.ssl_certificate_key->lengths == NULL)
         {
-            plcf->upstream.ssl_passwords =
-                  ngx_ssl_preserve_passwords(cf, plcf->upstream.ssl_passwords);
-            if (plcf->upstream.ssl_passwords == NULL) {
-                return NGX_ERROR;
-            }
-
-        } else {
             if (ngx_ssl_certificate(cf, plcf->upstream.ssl,
                                     &plcf->upstream.ssl_certificate->value,
                                     &plcf->upstream.ssl_certificate_key->value,