move ssl cipher list from compiletime to context creation time option

More flexible this way... NULL for the new member means use
the ssl library default set of ciphers, so as long as your info
struct is zerod by bss or memset, you don't need to do anything
about this change unless you want to set the cipher list.

Signed-off-by: Andy Green <andy.green@linaro.org>

diff --git a/README.build b/README.build
index 2787bde..64d98cf 100644 (file)
--- a/README.build
+++ b/README.build
@@ -165,15 +165,6 @@ for later protocol versions... unlikely
  - AWAITING_TIMEOUT default 5: after this many seconds without a response, the
 server will hang up on the client
 
- - CIPHERS_LIST_STRING default "DEFAULT": SSL Cipher selection.  It's advisable
-to tweak the ciphers allowed to be negotiated on secure connections for
-performance reasons, otherwise a slow algorithm may be selected by the two
-endpoints and the server could expend most of its time just encrypting and
-decrypting data, severely limiting the amount of messages it will be able to
-handle per second.  For example::
-
-    "RC4-MD5:RC4-SHA:AES128-SHA:AES256-SHA:HIGH:!DSS:!aNULL"
-
  - SYSTEM_RANDOM_FILEPATH default "/dev/urandom": if your random device differs
 you can set it here
 

diff --git a/README.coding b/README.coding
index bb093fb..0231d03 100644 (file)
--- a/README.coding
+++ b/README.coding
@@ -209,3 +209,18 @@ Note that BSDs don't support keepalive time / probes / inteveral per-socket
 like Linux does.  On those systems you can enable keepalive by a nonzero
 value in ka_time, but the systemwide kernel settings for the time / probes/
 interval are used, regardless of what nonzero value is in ka_time.
+
+Optimizing SSL connections
+--------------------------
+
+There's a member ssl_cipher_list in the lws_context_creation_info struct
+which allows the user code to restrict the possible cipher selection at
+context-creation time.
+
+You might want to look into that to stop the ssl peers selecting a ciher which
+is too computationally expensive.  To use it, point it to a string like
+
+"RC4-MD5:RC4-SHA:AES128-SHA:AES256-SHA:HIGH:!DSS:!aNULL"
+
+if left NULL, then the "DEFAULT" set of ciphers are all possible to select.
+

diff --git a/changelog b/changelog
index 9b76f08..97c0f64 100644 (file)
--- a/changelog
+++ b/changelog
@@ -10,6 +10,10 @@ User api additions
        and get a LWS_CALLBACK_HTTP_WRITEABLE callback, the same way you can
        regulate writes with a websocket protocol connection.
 
+ - A new member in the context creation parameter struct "ssl_cipher_list" is
+       added, replacing CIPHERS_LIST_STRING.  NULL means use the ssl library
+       default list of ciphers.
+
 User api changes
 ----------------
 
@@ -27,6 +31,8 @@ User api removal
        were using it to get user_space, you need to adapt your code to only
        use user_space inside the user callback.
 
+ - CIPHERS_LIST_STRING is removed
+
 
 v1.21-chrome26-firefox18
 ========================

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index 337582d..7414fe7 100644 (file)
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -1657,7 +1657,8 @@ libwebsocket_create_context(struct lws_context_creation_info *info)
 #endif
        lwsl_info(" SPEC_LATEST_SUPPORTED: %u\n", SPEC_LATEST_SUPPORTED);
        lwsl_info(" AWAITING_TIMEOUT: %u\n", AWAITING_TIMEOUT);
-       lwsl_info(" CIPHERS_LIST_STRING: '%s'\n", CIPHERS_LIST_STRING);
+       if (info->ssl_cipher_list)
+               lwsl_info(" SSL ciphers: '%s'\n", info->ssl_cipher_list);
        lwsl_info(" SYSTEM_RANDOM_FILEPATH: '%s'\n", SYSTEM_RANDOM_FILEPATH);
        lwsl_info(" LWS_MAX_ZLIB_CONN_BUFFER: %u\n", LWS_MAX_ZLIB_CONN_BUFFER);
 
@@ -1877,7 +1878,9 @@ libwebsocket_create_context(struct lws_context_creation_info *info)
        SSL_CTX_set_options(context->ssl_ctx, SSL_OP_NO_COMPRESSION);
 #endif
        SSL_CTX_set_options(context->ssl_ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
-       SSL_CTX_set_cipher_list(context->ssl_ctx, CIPHERS_LIST_STRING);
+       if (info->ssl_cipher_list)
+               SSL_CTX_set_cipher_list(context->ssl_ctx,
+                                               info->ssl_cipher_list);
 
 #ifndef LWS_NO_CLIENT
 
@@ -1908,8 +1911,9 @@ libwebsocket_create_context(struct lws_context_creation_info *info)
 #endif
                SSL_CTX_set_options(context->ssl_client_ctx,
                                               SSL_OP_CIPHER_SERVER_PREFERENCE);
-               SSL_CTX_set_cipher_list(context->ssl_client_ctx,
-                                                          CIPHERS_LIST_STRING);
+               if (info->ssl_cipher_list)
+                       SSL_CTX_set_cipher_list(context->ssl_client_ctx,
+                                                       info->ssl_cipher_list);
 
                /* openssl init for cert verification (for client sockets) */
                if (!info->ssl_ca_filepath) {

diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index b7f43fc..28e649c 100644 (file)
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -759,6 +759,9 @@ struct libwebsocket_extension {
  * @ssl_private_key_filepath: filepath to private key if wanting SSL mode,
  *                     else ignored
  * @ssl_ca_filepath: CA certificate filepath or NULL
+ * @ssl_cipher_list:   List of valid ciphers to use (eg,
+ *                     "RC4-MD5:RC4-SHA:AES128-SHA:AES256-SHA:HIGH:!DSS:!aNULL"
+ *                     or you can leave it as NULL to get "DEFAULT"
  * @gid:       group id to change to after setting listen socket, or -1.
  * @uid:       user id to change to after setting listen socket, or -1.
  * @options:   0, or LWS_SERVER_OPTION_DEFEAT_CLIENT_MASK
@@ -781,6 +784,7 @@ struct lws_context_creation_info {
        const char *ssl_cert_filepath;
        const char *ssl_private_key_filepath;
        const char *ssl_ca_filepath;
+       const char *ssl_cipher_list;
        int gid;
        int uid;
        unsigned int options;

diff --git a/libwebsockets-api-doc.html b/libwebsockets-api-doc.html
index 42a37b0..a38145c 100644 (file)
--- a/libwebsockets-api-doc.html
+++ b/libwebsockets-api-doc.html
@@ -637,7 +637,7 @@ and servers get LWS_CALLBACK_SERVER_WRITEABLE.
 called when a client connects to
 the server at network level; the connection is accepted but then
 passed to this callback to decide whether to hang up immediately
-or not, based on the client IP.  <tt><b>user</b></tt> contains the connection
+or not, based on the client IP.  <tt><b>in</b></tt> contains the connection
 socket's descriptor.  Return non-zero to terminate
 the connection before sending or receiving anything.
 Because this happens immediately after the network connection
@@ -969,6 +969,7 @@ all sessions, etc, if it wants
 &nbsp; &nbsp; <i>const char *</i> <b>ssl_cert_filepath</b>;<br>
 &nbsp; &nbsp; <i>const char *</i> <b>ssl_private_key_filepath</b>;<br>
 &nbsp; &nbsp; <i>const char *</i> <b>ssl_ca_filepath</b>;<br>
+&nbsp; &nbsp; <i>const char *</i> <b>ssl_cipher_list</b>;<br>
 &nbsp; &nbsp; <i>int</i> <b>gid</b>;<br>
 &nbsp; &nbsp; <i>int</i> <b>uid</b>;<br>
 &nbsp; &nbsp; <i>unsigned int</i> <b>options</b>;<br>
@@ -1004,6 +1005,10 @@ server cert from, otherwise NULL for unencrypted
 else ignored
 <dt><b>ssl_ca_filepath</b>
 <dd>CA certificate filepath or NULL
+<dt><b>ssl_cipher_list</b>
+<dd>List of valid ciphers to use (eg,
+"RC4-MD5:RC4-SHA:AES128-SHA:AES256-SHA:HIGH:!DSS:!aNULL"
+or you can leave it as NULL to get "DEFAULT"
 <dt><b>gid</b>
 <dd>group id to change to after setting listen socket, or -1.
 <dt><b>uid</b>