[nginx] Stream: ssl_preread module.

Vladimir Homutov vl at nginx.com
Thu Sep 15 11:57:54 UTC 2016


details:   http://hg.nginx.org/nginx/rev/060d71292b69
branches:  
changeset: 6695:060d71292b69
user:      Vladimir Homutov <vl at nginx.com>
date:      Thu Sep 15 14:56:51 2016 +0300
description:
Stream: ssl_preread module.

The ssl_preread module extracts information from the SSL Client Hello message
without terminating SSL.  Currently, only $ssl_preread_server_name variable
is supported, which contains server name from the SNI extension.

diffstat:

 auto/modules                               |   10 +
 auto/options                               |    4 +
 src/stream/ngx_stream_ssl_preread_module.c |  448 +++++++++++++++++++++++++++++
 3 files changed, 462 insertions(+), 0 deletions(-)

diffs (500 lines):

diff -r ea9dfe2f62e7 -r 060d71292b69 auto/modules
--- a/auto/modules	Thu Sep 15 14:56:02 2016 +0300
+++ b/auto/modules	Thu Sep 15 14:56:51 2016 +0300
@@ -1120,6 +1120,16 @@ if [ $STREAM != NO ]; then
 
         . auto/module
     fi
+
+    if [ $STREAM_SSL_PREREAD = YES ]; then
+        ngx_module_name=ngx_stream_ssl_preread_module
+        ngx_module_deps=
+        ngx_module_srcs=src/stream/ngx_stream_ssl_preread_module.c
+        ngx_module_libs=
+        ngx_module_link=$STREAM_SSL_PREREAD
+
+        . auto/module
+    fi
 fi
 
 
diff -r ea9dfe2f62e7 -r 060d71292b69 auto/options
--- a/auto/options	Thu Sep 15 14:56:02 2016 +0300
+++ b/auto/options	Thu Sep 15 14:56:51 2016 +0300
@@ -126,6 +126,7 @@ STREAM_RETURN=YES
 STREAM_UPSTREAM_HASH=YES
 STREAM_UPSTREAM_LEAST_CONN=YES
 STREAM_UPSTREAM_ZONE=YES
+STREAM_SSL_PREREAD=NO
 
 DYNAMIC_MODULES=
 
@@ -301,6 +302,8 @@ use the \"--with-mail_ssl_module\" optio
         --with-stream_geoip_module)      STREAM_GEOIP=YES           ;;
         --with-stream_geoip_module=dynamic)
                                          STREAM_GEOIP=DYNAMIC       ;;
+        --with-stream_ssl_preread_module)
+                                         STREAM_SSL_PREREAD=YES     ;;
         --without-stream_limit_conn_module)
                                          STREAM_LIMIT_CONN=NO       ;;
         --without-stream_access_module)  STREAM_ACCESS=NO           ;;
@@ -508,6 +511,7 @@ cat << END
   --with-stream_realip_module        enable ngx_stream_realip_module
   --with-stream_geoip_module         enable ngx_stream_geoip_module
   --with-stream_geoip_module=dynamic enable dynamic ngx_stream_geoip_module
+  --with-stream_ssl_preread_module   enable ngx_stream_ssl_preread_module
   --without-stream_limit_conn_module disable ngx_stream_limit_conn_module
   --without-stream_access_module     disable ngx_stream_access_module
   --without-stream_geo_module        disable ngx_stream_geo_module
diff -r ea9dfe2f62e7 -r 060d71292b69 src/stream/ngx_stream_ssl_preread_module.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/stream/ngx_stream_ssl_preread_module.c	Thu Sep 15 14:56:51 2016 +0300
@@ -0,0 +1,448 @@
+
+/*
+ * Copyright (C) Nginx, Inc.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_stream.h>
+
+
+typedef struct {
+    ngx_flag_t      enabled;
+} ngx_stream_ssl_preread_srv_conf_t;
+
+
+typedef struct {
+    size_t          left;
+    size_t          size;
+    u_char         *pos;
+    u_char         *dst;
+    u_char          buf[4];
+    ngx_str_t       host;
+    ngx_log_t      *log;
+    ngx_pool_t     *pool;
+    ngx_uint_t      state;
+} ngx_stream_ssl_preread_ctx_t;
+
+
+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_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_add_variables(ngx_conf_t *cf);
+static void *ngx_stream_ssl_preread_create_srv_conf(ngx_conf_t *cf);
+static char *ngx_stream_ssl_preread_merge_srv_conf(ngx_conf_t *cf, void *parent,
+    void *child);
+static ngx_int_t ngx_stream_ssl_preread_init(ngx_conf_t *cf);
+
+
+static ngx_command_t  ngx_stream_ssl_preread_commands[] = {
+
+    { ngx_string("ssl_preread"),
+      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_STREAM_SRV_CONF_OFFSET,
+      offsetof(ngx_stream_ssl_preread_srv_conf_t, enabled),
+      NULL },
+
+      ngx_null_command
+};
+
+
+static ngx_stream_module_t  ngx_stream_ssl_preread_module_ctx = {
+    ngx_stream_ssl_preread_add_variables,   /* preconfiguration */
+    ngx_stream_ssl_preread_init,            /* postconfiguration */
+
+    NULL,                                   /* create main configuration */
+    NULL,                                   /* init main configuration */
+
+    ngx_stream_ssl_preread_create_srv_conf, /* create server configuration */
+    ngx_stream_ssl_preread_merge_srv_conf   /* merge server configuration */
+};
+
+
+ngx_module_t  ngx_stream_ssl_preread_module = {
+    NGX_MODULE_V1,
+    &ngx_stream_ssl_preread_module_ctx,     /* module context */
+    ngx_stream_ssl_preread_commands,        /* module directives */
+    NGX_STREAM_MODULE,                      /* module type */
+    NULL,                                   /* init master */
+    NULL,                                   /* init module */
+    NULL,                                   /* init process */
+    NULL,                                   /* init thread */
+    NULL,                                   /* exit thread */
+    NULL,                                   /* exit process */
+    NULL,                                   /* exit master */
+    NGX_MODULE_V1_PADDING
+};
+
+
+static ngx_stream_variable_t  ngx_stream_ssl_preread_vars[] = {
+
+    { ngx_string("ssl_preread_server_name"), NULL,
+      ngx_stream_ssl_preread_server_name_variable, 0, 0, 0 },
+
+    { ngx_null_string, NULL, NULL, 0, 0, 0 }
+};
+
+
+static ngx_int_t
+ngx_stream_ssl_preread_handler(ngx_stream_session_t *s)
+{
+    u_char                             *last, *p;
+    size_t                              len;
+    ngx_int_t                           rc;
+    ngx_connection_t                   *c;
+    ngx_stream_ssl_preread_ctx_t       *ctx;
+    ngx_stream_ssl_preread_srv_conf_t  *sscf;
+
+    c = s->connection;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_STREAM, c->log, 0, "ssl preread handler");
+
+    sscf = ngx_stream_get_module_srv_conf(s, ngx_stream_ssl_preread_module);
+
+    if (!sscf->enabled) {
+        return NGX_DECLINED;
+    }
+
+    if (c->type != SOCK_STREAM) {
+        return NGX_DECLINED;
+    }
+
+    if (c->buffer == NULL) {
+        return NGX_AGAIN;
+    }
+
+    ctx = ngx_stream_get_module_ctx(s, ngx_stream_ssl_preread_module);
+    if (ctx == NULL) {
+        ctx = ngx_pcalloc(c->pool, sizeof(ngx_stream_ssl_preread_ctx_t));
+        if (ctx == NULL) {
+            return NGX_ERROR;
+        }
+
+        ngx_stream_set_ctx(s, ctx, ngx_stream_ssl_preread_module);
+
+        ctx->pool = c->pool;
+        ctx->log = c->log;
+        ctx->pos = c->buffer->pos;
+    }
+
+    p = ctx->pos;
+    last = c->buffer->last;
+
+    while (last - p >= 5) {
+
+        if (p[0] != 0x16) {
+            ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                          "ssl preread: not a handshake");
+            return NGX_DECLINED;
+        }
+
+        if (p[1] != 3 || p[2] == 0) {
+            ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                          "ssl preread: unsupported SSL version");
+            return NGX_DECLINED;
+        }
+
+        len = (p[3] << 8) + p[4];
+
+        /* read the whole record before parsing */
+        if ((size_t) (last - p) < len + 5) {
+            break;
+        }
+
+        p += 5;
+
+        rc = ngx_stream_ssl_preread_parse_record(ctx, p, p + len);
+        if (rc != NGX_AGAIN) {
+            return rc;
+        }
+
+        p += len;
+    }
+
+    ctx->pos = p;
+
+    return NGX_AGAIN;
+}
+
+
+static ngx_int_t
+ngx_stream_ssl_preread_parse_record(ngx_stream_ssl_preread_ctx_t *ctx,
+    u_char *pos, u_char *last)
+{
+    size_t   left, n, size;
+    u_char  *dst, *p;
+
+    enum {
+        sw_start = 0,
+        sw_header,          /* handshake msg_type, length */
+        sw_head_tail,       /* version, random */
+        sw_sid_len,         /* session_id length */
+        sw_sid,             /* session_id */
+        sw_cs_len,          /* cipher_suites length */
+        sw_cs,              /* cipher_suites */
+        sw_cm_len,          /* compression_methods length */
+        sw_cm,              /* compression_methods */
+        sw_ext,             /* extension */
+        sw_ext_header,      /* extension_type, extension_data length */
+        sw_sni_len,         /* SNI length */
+        sw_sni_host_head,   /* SNI name_type, host_name length */
+        sw_sni_host         /* SNI host_name */
+    } state;
+
+    ngx_log_debug2(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                   "ssl preread: state %ui left %z", ctx->state, ctx->left);
+
+    state = ctx->state;
+    size = ctx->size;
+    left = ctx->left;
+    dst = ctx->dst;
+    p = ctx->buf;
+
+    for ( ;; ) {
+        n = ngx_min((size_t) (last - pos), size);
+
+        if (dst) {
+            dst = ngx_cpymem(dst, pos, n);
+        }
+
+        pos += n;
+        size -= n;
+        left -= n;
+
+        if (size != 0) {
+            break;
+        }
+
+        switch (state) {
+
+        case sw_start:
+            state = sw_header;
+            dst = p;
+            size = 4;
+            left = size;
+            break;
+
+        case sw_header:
+            if (p[0] != 1) {
+                ngx_log_debug(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                              "ssl preread: not a client hello");
+                return NGX_DECLINED;
+            }
+
+            state = sw_head_tail;
+            dst = NULL;
+            size = 34;
+            left = (p[1] << 16) + (p[2] << 8) + p[3];
+            break;
+
+        case sw_head_tail:
+            state = sw_sid_len;
+            dst = p;
+            size = 1;
+            break;
+
+        case sw_sid_len:
+            state = sw_sid;
+            dst = NULL;
+            size = p[0];
+            break;
+
+        case sw_sid:
+            state = sw_cs_len;
+            dst = p;
+            size = 2;
+            break;
+
+        case sw_cs_len:
+            state = sw_cs;
+            dst = NULL;
+            size = (p[0] << 8) + p[1];
+            break;
+
+        case sw_cs:
+            state = sw_cm_len;
+            dst = p;
+            size = 1;
+            break;
+
+        case sw_cm_len:
+            state = sw_cm;
+            dst = NULL;
+            size = p[0];
+            break;
+
+        case sw_cm:
+            if (left == 0) {
+                /* no extensions */
+                return NGX_OK;
+            }
+
+            state = sw_ext;
+            dst = p;
+            size = 2;
+            break;
+
+        case sw_ext:
+            if (left == 0) {
+                return NGX_OK;
+            }
+
+            state = sw_ext_header;
+            dst = p;
+            size = 4;
+            break;
+
+        case sw_ext_header:
+            if (p[0] == 0 && p[1] == 0) {
+                /* SNI extension */
+                state = sw_sni_len;
+                dst = NULL;
+                size = 2;
+                break;
+            }
+
+            state = sw_ext;
+            dst = NULL;
+            size = (p[2] << 8) + p[3];
+            break;
+
+        case sw_sni_len:
+            state = sw_sni_host_head;
+            dst = p;
+            size = 3;
+            break;
+
+        case sw_sni_host_head:
+            if (p[0] != 0) {
+                ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                               "ssl preread: SNI hostname type is not DNS");
+                return NGX_DECLINED;
+            }
+
+            state = sw_sni_host;
+            size = (p[1] << 8) + p[2];
+
+            ctx->host.data = ngx_pnalloc(ctx->pool, size);
+            if (ctx->host.data == NULL) {
+                return NGX_ERROR;
+            }
+
+            ctx->host.len = size;
+            dst = ctx->host.data;
+            break;
+
+        case sw_sni_host:
+            ngx_log_debug1(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                           "ssl preread: SNI hostname \"%V\"", &ctx->host);
+            return NGX_OK;
+        }
+
+        if (left < size) {
+           ngx_log_debug0(NGX_LOG_DEBUG_STREAM, ctx->log, 0,
+                          "ssl preread: failed to parse handshake");
+           return NGX_DECLINED;
+        }
+    }
+
+    ctx->state = state;
+    ctx->size = size;
+    ctx->left = left;
+    ctx->dst = dst;
+
+    return NGX_AGAIN;
+}
+
+
+static ngx_int_t
+ngx_stream_ssl_preread_server_name_variable(ngx_stream_session_t *s,
+    ngx_variable_value_t *v, uintptr_t data)
+{
+    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;
+    }
+
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+    v->len = ctx->host.len;
+    v->data = ctx->host.data;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_stream_ssl_preread_add_variables(ngx_conf_t *cf)
+{
+    ngx_stream_variable_t  *var, *v;
+
+    for (v = ngx_stream_ssl_preread_vars; v->name.len; v++) {
+        var = ngx_stream_add_variable(cf, &v->name, v->flags);
+        if (var == NULL) {
+            return NGX_ERROR;
+        }
+
+        var->get_handler = v->get_handler;
+        var->data = v->data;
+    }
+
+    return NGX_OK;
+}
+
+
+static void *
+ngx_stream_ssl_preread_create_srv_conf(ngx_conf_t *cf)
+{
+    ngx_stream_ssl_preread_srv_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_stream_ssl_preread_srv_conf_t));
+    if (conf == NULL) {
+        return NULL;
+    }
+
+    conf->enabled = NGX_CONF_UNSET;
+
+    return conf;
+}
+
+
+static char *
+ngx_stream_ssl_preread_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_stream_ssl_preread_srv_conf_t *prev = parent;
+    ngx_stream_ssl_preread_srv_conf_t *conf = child;
+
+    ngx_conf_merge_value(conf->enabled, prev->enabled, 0);
+
+    return NGX_CONF_OK;
+}
+
+
+static ngx_int_t
+ngx_stream_ssl_preread_init(ngx_conf_t *cf)
+{
+    ngx_stream_handler_pt        *h;
+    ngx_stream_core_main_conf_t  *cmcf;
+
+    cmcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_core_module);
+
+    h = ngx_array_push(&cmcf->phases[NGX_STREAM_PREREAD_PHASE].handlers);
+    if (h == NULL) {
+        return NGX_ERROR;
+    }
+
+    *h = ngx_stream_ssl_preread_handler;
+
+    return NGX_OK;
+}



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