diff --git a/CHANGES b/CHANGES
index 49465bc..571c33f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,24 @@
 
+Changes with nginx 1.23.1                                        19 Jul 2022
+
+    *) Feature: memory usage optimization in configurations with SSL
+       proxying.
+
+    *) Feature: looking up of IPv4 addresses while resolving now can be
+       disabled with the "ipv4=off" parameter of the "resolver" directive.
+
+    *) Change: the logging level of the "bad key share", "bad extension",
+       "bad cipher", and "bad ecpoint" SSL errors has been lowered from
+       "crit" to "info".
+
+    *) Bugfix: while returning byte ranges nginx did not remove the
+       "Content-Range" header line if it was present in the original backend
+       response.
+
+    *) Bugfix: a proxied response might be truncated during reconfiguration
+       on Linux; the bug had appeared in 1.17.5.
+
+
 Changes with nginx 1.23.0                                        21 Jun 2022
 
     *) Change in internal API: now header lines are represented as linked
diff --git a/CHANGES.ru b/CHANGES.ru
index 1339e8d..a0bf7f5 100644
--- a/CHANGES.ru
+++ b/CHANGES.ru
@@ -1,4 +1,24 @@
 
+Изменения в nginx 1.23.1                                          19.07.2022
+
+    *) Добавление: оптимизация использования памяти в конфигурациях с
+       SSL-проксированием.
+
+    *) Добавление: теперь с помощью параметра "ipv4=off" директивы
+       "resolver" можно запретить поиск IPv4-адресов при преобразовании имён
+       в адреса.
+
+    *) Изменение: уровень логгирования ошибок SSL "bad key share", "bad
+       extension", "bad cipher" и "bad ecpoint" понижен с уровня crit до
+       info.
+
+    *) Исправление: при возврате диапазонов nginx не удалял строку заголовка
+       "Content-Range", если она присутствовала в исходном ответе бэкенда.
+
+    *) Исправление: проксированный ответ мог быть отправлен не полностью при
+       переконфигурации на Linux; ошибка появилась в 1.17.5.
+
+
 Изменения в nginx 1.23.0                                          21.06.2022
 
     *) Изменение во внутреннем API: теперь строки заголовков представлены
diff --git a/src/core/nginx.h b/src/core/nginx.h
index 57e7b20..428e3a0 100644
--- a/src/core/nginx.h
+++ b/src/core/nginx.h
@@ -9,8 +9,8 @@
 #define _NGINX_H_INCLUDED_
 
 
-#define nginx_version      1023000
-#define NGINX_VERSION      "1.23.0"
+#define nginx_version      1023001
+#define NGINX_VERSION      "1.23.1"
 #define NGINX_VER          "nginx/" NGINX_VERSION
 
 #ifdef NGX_BUILD
diff --git a/src/core/ngx_resolver.c b/src/core/ngx_resolver.c
index b3947f5..c76c178 100644
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -157,6 +157,8 @@ ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
     cln->handler = ngx_resolver_cleanup;
     cln->data = r;
 
+    r->ipv4 = 1;
+
     ngx_rbtree_init(&r->name_rbtree, &r->name_sentinel,
                     ngx_resolver_rbtree_insert_value);
 
@@ -225,6 +227,23 @@ ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
         }
 
 #if (NGX_HAVE_INET6)
+        if (ngx_strncmp(names[i].data, "ipv4=", 5) == 0) {
+
+            if (ngx_strcmp(&names[i].data[5], "on") == 0) {
+                r->ipv4 = 1;
+
+            } else if (ngx_strcmp(&names[i].data[5], "off") == 0) {
+                r->ipv4 = 0;
+
+            } else {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                   "invalid parameter: %V", &names[i]);
+                return NULL;
+            }
+
+            continue;
+        }
+
         if (ngx_strncmp(names[i].data, "ipv6=", 5) == 0) {
 
             if (ngx_strcmp(&names[i].data[5], "on") == 0) {
@@ -273,6 +292,14 @@ ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
         }
     }
 
+#if (NGX_HAVE_INET6)
+    if (r->ipv4 + r->ipv6 == 0) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                           "\"ipv4\" and \"ipv6\" cannot both be \"off\"");
+        return NULL;
+    }
+#endif
+
     if (n && r->connections.nelts == 0) {
         ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "no name servers defined");
         return NULL;
@@ -836,7 +863,7 @@ ngx_resolve_name_locked(ngx_resolver_t *r, ngx_resolver_ctx_t *ctx,
         r->last_connection = 0;
     }
 
-    rn->naddrs = (u_short) -1;
+    rn->naddrs = r->ipv4 ? (u_short) -1 : 0;
     rn->tcp = 0;
 #if (NGX_HAVE_INET6)
     rn->naddrs6 = r->ipv6 ? (u_short) -1 : 0;
@@ -1263,7 +1290,7 @@ ngx_resolver_send_query(ngx_resolver_t *r, ngx_resolver_node_t *rn)
         rec->log.action = "resolving";
     }
 
-    if (rn->naddrs == (u_short) -1) {
+    if (rn->query && rn->naddrs == (u_short) -1) {
         rc = rn->tcp ? ngx_resolver_send_tcp_query(r, rec, rn->query, rn->qlen)
                      : ngx_resolver_send_udp_query(r, rec, rn->query, rn->qlen);
 
@@ -1765,10 +1792,13 @@ ngx_resolver_process_response(ngx_resolver_t *r, u_char *buf, size_t n,
              q = ngx_queue_next(q))
         {
             rn = ngx_queue_data(q, ngx_resolver_node_t, queue);
-            qident = (rn->query[0] << 8) + rn->query[1];
 
-            if (qident == ident) {
-                goto dns_error_name;
+            if (rn->query) {
+                qident = (rn->query[0] << 8) + rn->query[1];
+
+                if (qident == ident) {
+                    goto dns_error_name;
+                }
             }
 
 #if (NGX_HAVE_INET6)
@@ -3645,7 +3675,7 @@ ngx_resolver_create_name_query(ngx_resolver_t *r, ngx_resolver_node_t *rn,
     len = sizeof(ngx_resolver_hdr_t) + nlen + sizeof(ngx_resolver_qs_t);
 
 #if (NGX_HAVE_INET6)
-    p = ngx_resolver_alloc(r, r->ipv6 ? len * 2 : len);
+    p = ngx_resolver_alloc(r, len * (r->ipv4 + r->ipv6));
 #else
     p = ngx_resolver_alloc(r, len);
 #endif
@@ -3658,19 +3688,21 @@ ngx_resolver_create_name_query(ngx_resolver_t *r, ngx_resolver_node_t *rn,
 
 #if (NGX_HAVE_INET6)
     if (r->ipv6) {
-        rn->query6 = p + len;
+        rn->query6 = r->ipv4 ? (p + len) : p;
     }
 #endif
 
     query = (ngx_resolver_hdr_t *) p;
 
-    ident = ngx_random();
+    if (r->ipv4) {
+        ident = ngx_random();
 
-    ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
-                   "resolve: \"%V\" A %i", name, ident & 0xffff);
+        ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
+                       "resolve: \"%V\" A %i", name, ident & 0xffff);
 
-    query->ident_hi = (u_char) ((ident >> 8) & 0xff);
-    query->ident_lo = (u_char) (ident & 0xff);
+        query->ident_hi = (u_char) ((ident >> 8) & 0xff);
+        query->ident_lo = (u_char) (ident & 0xff);
+    }
 
     /* recursion query */
     query->flags_hi = 1; query->flags_lo = 0;
@@ -3731,7 +3763,9 @@ ngx_resolver_create_name_query(ngx_resolver_t *r, ngx_resolver_node_t *rn,
 
     p = rn->query6;
 
-    ngx_memcpy(p, rn->query, rn->qlen);
+    if (r->ipv4) {
+        ngx_memcpy(p, rn->query, rn->qlen);
+    }
 
     query = (ngx_resolver_hdr_t *) p;
 
diff --git a/src/core/ngx_resolver.h b/src/core/ngx_resolver.h
index 0bd3921..06026b7 100644
--- a/src/core/ngx_resolver.h
+++ b/src/core/ngx_resolver.h
@@ -175,8 +175,10 @@ struct ngx_resolver_s {
     ngx_queue_t               srv_expire_queue;
     ngx_queue_t               addr_expire_queue;
 
+    unsigned                  ipv4:1;
+
 #if (NGX_HAVE_INET6)
-    ngx_uint_t                ipv6;                 /* unsigned  ipv6:1; */
+    unsigned                  ipv6:1;
     ngx_rbtree_t              addr6_rbtree;
     ngx_rbtree_node_t         addr6_sentinel;
     ngx_queue_t               addr6_resend_queue;
diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index 975f959..7b0417e 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -3343,6 +3343,12 @@ ngx_ssl_connection_error(ngx_connection_t *c, int sslerr, ngx_err_t err,
 #ifdef SSL_R_NO_SUITABLE_KEY_SHARE
             || n == SSL_R_NO_SUITABLE_KEY_SHARE                      /*  101 */
 #endif
+#ifdef SSL_R_BAD_KEY_SHARE
+            || n == SSL_R_BAD_KEY_SHARE                              /*  108 */
+#endif
+#ifdef SSL_R_BAD_EXTENSION
+            || n == SSL_R_BAD_EXTENSION                              /*  110 */
+#endif
 #ifdef SSL_R_NO_SUITABLE_SIGNATURE_ALGORITHM
             || n == SSL_R_NO_SUITABLE_SIGNATURE_ALGORITHM            /*  118 */
 #endif
@@ -3357,6 +3363,9 @@ ngx_ssl_connection_error(ngx_connection_t *c, int sslerr, ngx_err_t err,
             || n == SSL_R_NO_CIPHERS_PASSED                          /*  182 */
 #endif
             || n == SSL_R_NO_CIPHERS_SPECIFIED                       /*  183 */
+#ifdef SSL_R_BAD_CIPHER
+            || n == SSL_R_BAD_CIPHER                                 /*  186 */
+#endif
             || n == SSL_R_NO_COMPRESSION_SPECIFIED                   /*  187 */
             || n == SSL_R_NO_SHARED_CIPHER                           /*  193 */
             || n == SSL_R_RECORD_LENGTH_MISMATCH                     /*  213 */
@@ -3391,6 +3400,9 @@ ngx_ssl_connection_error(ngx_connection_t *c, int sslerr, ngx_err_t err,
 #ifdef SSL_R_APPLICATION_DATA_ON_SHUTDOWN
             || n == SSL_R_APPLICATION_DATA_ON_SHUTDOWN               /*  291 */
 #endif
+#ifdef SSL_R_BAD_ECPOINT
+            || n == SSL_R_BAD_ECPOINT                                /*  306 */
+#endif
 #ifdef SSL_R_RENEGOTIATE_EXT_TOO_LONG
             || n == SSL_R_RENEGOTIATE_EXT_TOO_LONG                   /*  335 */
             || n == SSL_R_RENEGOTIATION_ENCODING_ERR                 /*  336 */
diff --git a/src/http/modules/ngx_http_grpc_module.c b/src/http/modules/ngx_http_grpc_module.c
index 617814e..5833286 100644
--- a/src/http/modules/ngx_http_grpc_module.c
+++ b/src/http/modules/ngx_http_grpc_module.c
@@ -209,6 +209,8 @@ static char *ngx_http_grpc_ssl_password_file(ngx_conf_t *cf,
     ngx_command_t *cmd, void *conf);
 static char *ngx_http_grpc_ssl_conf_command_check(ngx_conf_t *cf, void *post,
     void *data);
+static ngx_int_t ngx_http_grpc_merge_ssl(ngx_conf_t *cf,
+    ngx_http_grpc_loc_conf_t *conf, ngx_http_grpc_loc_conf_t *prev);
 static ngx_int_t ngx_http_grpc_set_ssl(ngx_conf_t *cf,
     ngx_http_grpc_loc_conf_t *glcf);
 #endif
@@ -562,7 +564,7 @@ ngx_http_grpc_handler(ngx_http_request_t *r)
         ctx->host = glcf->host;
 
 #if (NGX_HTTP_SSL)
-        u->ssl = (glcf->upstream.ssl != NULL);
+        u->ssl = glcf->ssl;
 
         if (u->ssl) {
             ngx_str_set(&u->schema, "grpcs://");
@@ -4463,6 +4465,10 @@ ngx_http_grpc_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
 
 #if (NGX_HTTP_SSL)
 
+    if (ngx_http_grpc_merge_ssl(cf, conf, prev) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
     ngx_conf_merge_value(conf->upstream.ssl_session_reuse,
                               prev->upstream.ssl_session_reuse, 1);
 
@@ -4524,7 +4530,7 @@ ngx_http_grpc_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
         conf->grpc_values = prev->grpc_values;
 
 #if (NGX_HTTP_SSL)
-        conf->upstream.ssl = prev->upstream.ssl;
+        conf->ssl = prev->ssl;
 #endif
     }
 
@@ -4874,16 +4880,62 @@ ngx_http_grpc_ssl_conf_command_check(ngx_conf_t *cf, void *post, void *data)
 
 
 static ngx_int_t
-ngx_http_grpc_set_ssl(ngx_conf_t *cf, ngx_http_grpc_loc_conf_t *glcf)
+ngx_http_grpc_merge_ssl(ngx_conf_t *cf, ngx_http_grpc_loc_conf_t *conf,
+    ngx_http_grpc_loc_conf_t *prev)
 {
-    ngx_pool_cleanup_t  *cln;
+    ngx_uint_t  preserve;
+
+    if (conf->ssl_protocols == 0
+        && conf->ssl_ciphers.data == NULL
+        && conf->upstream.ssl_certificate == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_certificate_key == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_passwords == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_verify == NGX_CONF_UNSET
+        && conf->ssl_verify_depth == NGX_CONF_UNSET_UINT
+        && conf->ssl_trusted_certificate.data == NULL
+        && conf->ssl_crl.data == NULL
+        && conf->upstream.ssl_session_reuse == NGX_CONF_UNSET
+        && conf->ssl_conf_commands == NGX_CONF_UNSET_PTR)
+    {
+        if (prev->upstream.ssl) {
+            conf->upstream.ssl = prev->upstream.ssl;
+            return NGX_OK;
+        }
 
-    glcf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
-    if (glcf->upstream.ssl == NULL) {
+        preserve = 1;
+
+    } else {
+        preserve = 0;
+    }
+
+    conf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
+    if (conf->upstream.ssl == NULL) {
         return NGX_ERROR;
     }
 
-    glcf->upstream.ssl->log = cf->log;
+    conf->upstream.ssl->log = cf->log;
+
+    /*
+     * special handling to preserve conf->upstream.ssl
+     * in the "http" section to inherit it to all servers
+     */
+
+    if (preserve) {
+        prev->upstream.ssl = conf->upstream.ssl;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_grpc_set_ssl(ngx_conf_t *cf, ngx_http_grpc_loc_conf_t *glcf)
+{
+    ngx_pool_cleanup_t  *cln;
+
+    if (glcf->upstream.ssl->ctx) {
+        return NGX_OK;
+    }
 
     if (ngx_ssl_create(glcf->upstream.ssl, glcf->ssl_protocols, NULL)
         != NGX_OK)
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index bb93030..54e2a39 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -236,6 +236,8 @@ static ngx_int_t ngx_http_proxy_rewrite_regex(ngx_conf_t *cf,
     ngx_http_proxy_rewrite_t *pr, ngx_str_t *regex, ngx_uint_t caseless);
 
 #if (NGX_HTTP_SSL)
+static ngx_int_t ngx_http_proxy_merge_ssl(ngx_conf_t *cf,
+    ngx_http_proxy_loc_conf_t *conf, ngx_http_proxy_loc_conf_t *prev);
 static ngx_int_t ngx_http_proxy_set_ssl(ngx_conf_t *cf,
     ngx_http_proxy_loc_conf_t *plcf);
 #endif
@@ -959,7 +961,7 @@ ngx_http_proxy_handler(ngx_http_request_t *r)
         ctx->vars = plcf->vars;
         u->schema = plcf->vars.schema;
 #if (NGX_HTTP_SSL)
-        u->ssl = (plcf->upstream.ssl != NULL);
+        u->ssl = plcf->ssl;
 #endif
 
     } else {
@@ -3724,6 +3726,10 @@ ngx_http_proxy_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
 
 #if (NGX_HTTP_SSL)
 
+    if (ngx_http_proxy_merge_ssl(cf, conf, prev) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
     ngx_conf_merge_value(conf->upstream.ssl_session_reuse,
                               prev->upstream.ssl_session_reuse, 1);
 
@@ -3857,7 +3863,7 @@ ngx_http_proxy_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
         conf->proxy_values = prev->proxy_values;
 
 #if (NGX_HTTP_SSL)
-        conf->upstream.ssl = prev->upstream.ssl;
+        conf->ssl = prev->ssl;
 #endif
     }
 
@@ -4923,16 +4929,62 @@ ngx_http_proxy_ssl_conf_command_check(ngx_conf_t *cf, void *post, void *data)
 
 
 static ngx_int_t
-ngx_http_proxy_set_ssl(ngx_conf_t *cf, ngx_http_proxy_loc_conf_t *plcf)
+ngx_http_proxy_merge_ssl(ngx_conf_t *cf, ngx_http_proxy_loc_conf_t *conf,
+    ngx_http_proxy_loc_conf_t *prev)
 {
-    ngx_pool_cleanup_t  *cln;
+    ngx_uint_t  preserve;
+
+    if (conf->ssl_protocols == 0
+        && conf->ssl_ciphers.data == NULL
+        && conf->upstream.ssl_certificate == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_certificate_key == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_passwords == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_verify == NGX_CONF_UNSET
+        && conf->ssl_verify_depth == NGX_CONF_UNSET_UINT
+        && conf->ssl_trusted_certificate.data == NULL
+        && conf->ssl_crl.data == NULL
+        && conf->upstream.ssl_session_reuse == NGX_CONF_UNSET
+        && conf->ssl_conf_commands == NGX_CONF_UNSET_PTR)
+    {
+        if (prev->upstream.ssl) {
+            conf->upstream.ssl = prev->upstream.ssl;
+            return NGX_OK;
+        }
 
-    plcf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
-    if (plcf->upstream.ssl == NULL) {
+        preserve = 1;
+
+    } else {
+        preserve = 0;
+    }
+
+    conf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
+    if (conf->upstream.ssl == NULL) {
         return NGX_ERROR;
     }
 
-    plcf->upstream.ssl->log = cf->log;
+    conf->upstream.ssl->log = cf->log;
+
+    /*
+     * special handling to preserve conf->upstream.ssl
+     * in the "http" section to inherit it to all servers
+     */
+
+    if (preserve) {
+        prev->upstream.ssl = conf->upstream.ssl;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_proxy_set_ssl(ngx_conf_t *cf, ngx_http_proxy_loc_conf_t *plcf)
+{
+    ngx_pool_cleanup_t  *cln;
+
+    if (plcf->upstream.ssl->ctx) {
+        return NGX_OK;
+    }
 
     if (ngx_ssl_create(plcf->upstream.ssl, plcf->ssl_protocols, NULL)
         != NGX_OK)
diff --git a/src/http/modules/ngx_http_range_filter_module.c b/src/http/modules/ngx_http_range_filter_module.c
index fa408b7..27d1875 100644
--- a/src/http/modules/ngx_http_range_filter_module.c
+++ b/src/http/modules/ngx_http_range_filter_module.c
@@ -425,6 +425,10 @@ ngx_http_range_singlepart_header(ngx_http_request_t *r,
         return NGX_ERROR;
     }
 
+    if (r->headers_out.content_range) {
+        r->headers_out.content_range->hash = 0;
+    }
+
     r->headers_out.content_range = content_range;
 
     content_range->hash = 1;
@@ -582,6 +586,11 @@ ngx_http_range_multipart_header(ngx_http_request_t *r,
         r->headers_out.content_length = NULL;
     }
 
+    if (r->headers_out.content_range) {
+        r->headers_out.content_range->hash = 0;
+        r->headers_out.content_range = NULL;
+    }
+
     return ngx_http_next_header_filter(r);
 }
 
@@ -598,6 +607,10 @@ ngx_http_range_not_satisfiable(ngx_http_request_t *r)
         return NGX_ERROR;
     }
 
+    if (r->headers_out.content_range) {
+        r->headers_out.content_range->hash = 0;
+    }
+
     r->headers_out.content_range = content_range;
 
     content_range->hash = 1;
diff --git a/src/http/modules/ngx_http_uwsgi_module.c b/src/http/modules/ngx_http_uwsgi_module.c
index 1dcee1e..4fc663d 100644
--- a/src/http/modules/ngx_http_uwsgi_module.c
+++ b/src/http/modules/ngx_http_uwsgi_module.c
@@ -96,6 +96,8 @@ static char *ngx_http_uwsgi_ssl_password_file(ngx_conf_t *cf,
     ngx_command_t *cmd, void *conf);
 static char *ngx_http_uwsgi_ssl_conf_command_check(ngx_conf_t *cf, void *post,
     void *data);
+static ngx_int_t ngx_http_uwsgi_merge_ssl(ngx_conf_t *cf,
+    ngx_http_uwsgi_loc_conf_t *conf, ngx_http_uwsgi_loc_conf_t *prev);
 static ngx_int_t ngx_http_uwsgi_set_ssl(ngx_conf_t *cf,
     ngx_http_uwsgi_loc_conf_t *uwcf);
 #endif
@@ -668,7 +670,7 @@ ngx_http_uwsgi_handler(ngx_http_request_t *r)
     if (uwcf->uwsgi_lengths == NULL) {
 
 #if (NGX_HTTP_SSL)
-        u->ssl = (uwcf->upstream.ssl != NULL);
+        u->ssl = uwcf->ssl;
 
         if (u->ssl) {
             ngx_str_set(&u->schema, "suwsgi://");
@@ -1865,6 +1867,10 @@ ngx_http_uwsgi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
 
 #if (NGX_HTTP_SSL)
 
+    if (ngx_http_uwsgi_merge_ssl(cf, conf, prev) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
     ngx_conf_merge_value(conf->upstream.ssl_session_reuse,
                               prev->upstream.ssl_session_reuse, 1);
 
@@ -1927,7 +1933,7 @@ ngx_http_uwsgi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
         conf->uwsgi_values = prev->uwsgi_values;
 
 #if (NGX_HTTP_SSL)
-        conf->upstream.ssl = prev->upstream.ssl;
+        conf->ssl = prev->ssl;
 #endif
     }
 
@@ -2455,16 +2461,62 @@ ngx_http_uwsgi_ssl_conf_command_check(ngx_conf_t *cf, void *post, void *data)
 
 
 static ngx_int_t
-ngx_http_uwsgi_set_ssl(ngx_conf_t *cf, ngx_http_uwsgi_loc_conf_t *uwcf)
+ngx_http_uwsgi_merge_ssl(ngx_conf_t *cf, ngx_http_uwsgi_loc_conf_t *conf,
+    ngx_http_uwsgi_loc_conf_t *prev)
 {
-    ngx_pool_cleanup_t  *cln;
+    ngx_uint_t  preserve;
+
+    if (conf->ssl_protocols == 0
+        && conf->ssl_ciphers.data == NULL
+        && conf->upstream.ssl_certificate == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_certificate_key == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_passwords == NGX_CONF_UNSET_PTR
+        && conf->upstream.ssl_verify == NGX_CONF_UNSET
+        && conf->ssl_verify_depth == NGX_CONF_UNSET_UINT
+        && conf->ssl_trusted_certificate.data == NULL
+        && conf->ssl_crl.data == NULL
+        && conf->upstream.ssl_session_reuse == NGX_CONF_UNSET
+        && conf->ssl_conf_commands == NGX_CONF_UNSET_PTR)
+    {
+        if (prev->upstream.ssl) {
+            conf->upstream.ssl = prev->upstream.ssl;
+            return NGX_OK;
+        }
 
-    uwcf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
-    if (uwcf->upstream.ssl == NULL) {
+        preserve = 1;
+
+    } else {
+        preserve = 0;
+    }
+
+    conf->upstream.ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
+    if (conf->upstream.ssl == NULL) {
         return NGX_ERROR;
     }
 
-    uwcf->upstream.ssl->log = cf->log;
+    conf->upstream.ssl->log = cf->log;
+
+    /*
+     * special handling to preserve conf->upstream.ssl
+     * in the "http" section to inherit it to all servers
+     */
+
+    if (preserve) {
+        prev->upstream.ssl = conf->upstream.ssl;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_uwsgi_set_ssl(ngx_conf_t *cf, ngx_http_uwsgi_loc_conf_t *uwcf)
+{
+    ngx_pool_cleanup_t  *cln;
+
+    if (uwcf->upstream.ssl->ctx) {
+        return NGX_OK;
+    }
 
     if (ngx_ssl_create(uwcf->upstream.ssl, uwcf->ssl_protocols, NULL)
         != NGX_OK)
diff --git a/src/os/unix/ngx_readv_chain.c b/src/os/unix/ngx_readv_chain.c
index 370a401..48fa0a7 100644
--- a/src/os/unix/ngx_readv_chain.c
+++ b/src/os/unix/ngx_readv_chain.c
@@ -46,6 +46,7 @@ ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain, off_t limit)
                 return 0;
 
             } else {
+                rev->ready = 0;
                 return NGX_AGAIN;
             }
         }
@@ -63,6 +64,7 @@ ngx_readv_chain(ngx_connection_t *c, ngx_chain_t *chain, off_t limit)
                        rev->pending_eof, rev->available);
 
         if (rev->available == 0 && !rev->pending_eof) {
+            rev->ready = 0;
             return NGX_AGAIN;
         }
     }
diff --git a/src/stream/ngx_stream_proxy_module.c b/src/stream/ngx_stream_proxy_module.c
index bd462ff..6b0d43e 100644
--- a/src/stream/ngx_stream_proxy_module.c
+++ b/src/stream/ngx_stream_proxy_module.c
@@ -103,6 +103,8 @@ static void ngx_stream_proxy_ssl_handshake(ngx_connection_t *pc);
 static void ngx_stream_proxy_ssl_save_session(ngx_connection_t *c);
 static ngx_int_t ngx_stream_proxy_ssl_name(ngx_stream_session_t *s);
 static ngx_int_t ngx_stream_proxy_ssl_certificate(ngx_stream_session_t *s);
+static ngx_int_t ngx_stream_proxy_merge_ssl(ngx_conf_t *cf,
+    ngx_stream_proxy_srv_conf_t *conf, ngx_stream_proxy_srv_conf_t *prev);
 static ngx_int_t ngx_stream_proxy_set_ssl(ngx_conf_t *cf,
     ngx_stream_proxy_srv_conf_t *pscf);
 
@@ -801,7 +803,7 @@ ngx_stream_proxy_init_upstream(ngx_stream_session_t *s)
 
 #if (NGX_STREAM_SSL)
 
-    if (pc->type == SOCK_STREAM && pscf->ssl) {
+    if (pc->type == SOCK_STREAM && pscf->ssl_enable) {
 
         if (u->proxy_protocol) {
             if (ngx_stream_proxy_send_proxy_protocol(s) != NGX_OK) {
@@ -2150,6 +2152,10 @@ ngx_stream_proxy_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
 
 #if (NGX_STREAM_SSL)
 
+    if (ngx_stream_proxy_merge_ssl(cf, conf, prev) != NGX_OK) {
+        return NGX_CONF_ERROR;
+    }
+
     ngx_conf_merge_value(conf->ssl_enable, prev->ssl_enable, 0);
 
     ngx_conf_merge_value(conf->ssl_session_reuse,
@@ -2199,16 +2205,62 @@ ngx_stream_proxy_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
 #if (NGX_STREAM_SSL)
 
 static ngx_int_t
-ngx_stream_proxy_set_ssl(ngx_conf_t *cf, ngx_stream_proxy_srv_conf_t *pscf)
+ngx_stream_proxy_merge_ssl(ngx_conf_t *cf, ngx_stream_proxy_srv_conf_t *conf,
+    ngx_stream_proxy_srv_conf_t *prev)
 {
-    ngx_pool_cleanup_t  *cln;
+    ngx_uint_t  preserve;
+
+    if (conf->ssl_protocols == 0
+        && conf->ssl_ciphers.data == NULL
+        && conf->ssl_certificate == NGX_CONF_UNSET_PTR
+        && conf->ssl_certificate_key == NGX_CONF_UNSET_PTR
+        && conf->ssl_passwords == NGX_CONF_UNSET_PTR
+        && conf->ssl_verify == NGX_CONF_UNSET
+        && conf->ssl_verify_depth == NGX_CONF_UNSET_UINT
+        && conf->ssl_trusted_certificate.data == NULL
+        && conf->ssl_crl.data == NULL
+        && conf->ssl_session_reuse == NGX_CONF_UNSET
+        && conf->ssl_conf_commands == NGX_CONF_UNSET_PTR)
+    {
+        if (prev->ssl) {
+            conf->ssl = prev->ssl;
+            return NGX_OK;
+        }
 
-    pscf->ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
-    if (pscf->ssl == NULL) {
+        preserve = 1;
+
+    } else {
+        preserve = 0;
+    }
+
+    conf->ssl = ngx_pcalloc(cf->pool, sizeof(ngx_ssl_t));
+    if (conf->ssl == NULL) {
         return NGX_ERROR;
     }
 
-    pscf->ssl->log = cf->log;
+    conf->ssl->log = cf->log;
+
+    /*
+     * special handling to preserve conf->ssl
+     * in the "stream" section to inherit it to all servers
+     */
+
+    if (preserve) {
+        prev->ssl = conf->ssl;
+    }
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_stream_proxy_set_ssl(ngx_conf_t *cf, ngx_stream_proxy_srv_conf_t *pscf)
+{
+    ngx_pool_cleanup_t  *cln;
+
+    if (pscf->ssl->ctx) {
+        return NGX_OK;
+    }
 
     if (ngx_ssl_create(pscf->ssl, pscf->ssl_protocols, NULL) != NGX_OK) {
         return NGX_ERROR;