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[nginx] Stream ssl_preread: $ssl_preread_protocol variable.

Roman Arutyunyan
July 12, 2018 11:52AM
details: http://hg.nginx.org/nginx/rev/3dfc1584ad75
branches:
changeset: 7314:3dfc1584ad75
user: Roman Arutyunyan <arut@nginx.com>
date: Wed Jul 11 17:56:51 2018 +0300
description:
Stream ssl_preread: $ssl_preread_protocol variable.

The variable keeps the latest SSL protocol version supported by the client.
The variable has the same format as $ssl_protocol.

The version is read from the client_version field of ClientHello. If the
supported_versions extension is present in the ClientHello, then the version
is set to TLSv1.3.

diffstat:

src/stream/ngx_stream_ssl_preread_module.c | 99 ++++++++++++++++++++++++++++-
1 files changed, 93 insertions(+), 6 deletions(-)

diffs (168 lines):

diff -r e45f09198dab -r 3dfc1584ad75 src/stream/ngx_stream_ssl_preread_module.c
--- a/src/stream/ngx_stream_ssl_preread_module.c Thu Jul 12 12:50:20 2018 +0300
+++ b/src/stream/ngx_stream_ssl_preread_module.c Wed Jul 11 17:56:51 2018 +0300
@@ -21,6 +21,7 @@ typedef struct {
u_char *pos;
u_char *dst;
u_char buf[4];
+ u_char version[2];
ngx_str_t host;
ngx_str_t alpn;
ngx_log_t *log;
@@ -32,6 +33,8 @@ typedef struct {
static ngx_int_t ngx_stream_ssl_preread_handler(ngx_stream_session_t *s);
static ngx_int_t ngx_stream_ssl_preread_parse_record(
ngx_stream_ssl_preread_ctx_t *ctx, u_char *pos, u_char *last);
+static ngx_int_t ngx_stream_ssl_preread_protocol_variable(
+ ngx_stream_session_t *s, ngx_stream_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_stream_ssl_preread_server_name_variable(
ngx_stream_session_t *s, ngx_stream_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_stream_ssl_preread_alpn_protocols_variable(
@@ -86,6 +89,9 @@ ngx_module_t ngx_stream_ssl_preread_mod

static ngx_stream_variable_t ngx_stream_ssl_preread_vars[] = {

+ { ngx_string("ssl_preread_protocol"), NULL,
+ ngx_stream_ssl_preread_protocol_variable, 0, 0, 0 },
+
{ ngx_string("ssl_preread_server_name"), NULL,
ngx_stream_ssl_preread_server_name_variable, 0, 0, 0 },

@@ -196,7 +202,8 @@ ngx_stream_ssl_preread_parse_record(ngx_
enum {
sw_start = 0,
sw_header, /* handshake msg_type, length */
- sw_head_tail, /* version, random */
+ sw_version, /* client_version */
+ sw_random, /* random */
sw_sid_len, /* session_id length */
sw_sid, /* session_id */
sw_cs_len, /* cipher_suites length */
@@ -210,7 +217,8 @@ ngx_stream_ssl_preread_parse_record(ngx_
sw_sni_host, /* SNI host_name */
sw_alpn_len, /* ALPN length */
sw_alpn_proto_len, /* ALPN protocol_name length */
- sw_alpn_proto_data /* ALPN protocol_name */
+ sw_alpn_proto_data, /* ALPN protocol_name */
+ sw_supver_len /* supported_versions length */
} state;

ngx_log_debug2(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
@@ -254,13 +262,19 @@ ngx_stream_ssl_preread_parse_record(ngx_
return NGX_DECLINED;
}

- state = sw_head_tail;
- dst = NULL;
- size = 34;
+ state = sw_version;
+ dst = ctx->version;
+ size = 2;
left = (p[1] << 16) + (p[2] << 8) + p[3];
break;

- case sw_head_tail:
+ case sw_version:
+ state = sw_random;
+ dst = NULL;
+ size = 32;
+ break;
+
+ case sw_random:
state = sw_sid_len;
dst = p;
size = 1;
@@ -334,6 +348,14 @@ ngx_stream_ssl_preread_parse_record(ngx_
break;
}

+ if (p[0] == 0 && p[1] == 43) {
+ /* supported_versions extension */
+ state = sw_supver_len;
+ dst = p;
+ size = 1;
+ break;
+ }
+
state = sw_ext;
dst = NULL;
size = (p[2] << 8) + p[3];
@@ -434,6 +456,19 @@ ngx_stream_ssl_preread_parse_record(ngx_
dst = NULL;
size = 0;
break;
+
+ case sw_supver_len:
+ ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+ "ssl preread: supported_versions");
+
+ /* set TLSv1.3 */
+ ctx->version[0] = 3;
+ ctx->version[1] = 4;
+
+ state = sw_ext;
+ dst = NULL;
+ size = p[0];
+ break;
}

if (left < size) {
@@ -454,6 +489,58 @@ ngx_stream_ssl_preread_parse_record(ngx_


static ngx_int_t
+ngx_stream_ssl_preread_protocol_variable(ngx_stream_session_t *s,
+ ngx_variable_value_t *v, uintptr_t data)
+{
+ ngx_str_t version;
+ ngx_stream_ssl_preread_ctx_t *ctx;
+
+ ctx = ngx_stream_get_module_ctx(s, ngx_stream_ssl_preread_module);
+
+ if (ctx == NULL) {
+ v->not_found = 1;
+ return NGX_OK;
+ }
+
+ /* SSL_get_version() format */
+
+ ngx_str_null(&version);
+
+ switch (ctx->version[0]) {
+ case 2:
+ ngx_str_set(&version, "SSLv2");
+ break;
+ case 3:
+ switch (ctx->version[1]) {
+ case 0:
+ ngx_str_set(&version, "SSLv3");
+ break;
+ case 1:
+ ngx_str_set(&version, "TLSv1");
+ break;
+ case 2:
+ ngx_str_set(&version, "TLSv1.1");
+ break;
+ case 3:
+ ngx_str_set(&version, "TLSv1.2");
+ break;
+ case 4:
+ ngx_str_set(&version, "TLSv1.3");
+ break;
+ }
+ }
+
+ v->valid = 1;
+ v->no_cacheable = 0;
+ v->not_found = 0;
+ v->len = version.len;
+ v->data = version.data;
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
ngx_stream_ssl_preread_server_name_variable(ngx_stream_session_t *s,
ngx_variable_value_t *v, uintptr_t data)
{
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[nginx] Stream ssl_preread: $ssl_preread_protocol variable.

Roman Arutyunyan 30 July 12, 2018 11:52AM



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