eliminate snprintf

The two cases where I introduced snprintf are either already
safe for buffer overflow or can be made so with one extra
statement, allowing sprintf.

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

diff --git a/lib/client.c b/lib/client.c
index c3fb2e8..397d4e5 100644 (file)
--- a/lib/client.c
+++ b/lib/client.c
@@ -710,8 +710,6 @@ libwebsockets_generate_client_handshake(struct libwebsocket_context *context,
        struct libwebsocket_extension *ext1;
        int ext_count = 0;
 #endif
-       static const char magic_websocket_guid[] =
-                                        "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
        /*
         * create the random key
@@ -841,12 +839,9 @@ libwebsockets_generate_client_handshake(struct libwebsocket_context *context,
 
        /* prepare the expected server accept response */
 
-#ifdef WIN32
-       n = _snprintf(buf, sizeof(buf), "%s%s", key_b64, magic_websocket_guid);
-#else
-       n = snprintf(buf, sizeof(buf), "%s%s", key_b64, magic_websocket_guid);
-#endif
-       buf[sizeof(buf) - 1] = '\0';
+       key_b64[39] = '\0'; /* enforce composed length below buf sizeof */
+       n = sprintf(buf, "%s258EAFA5-E914-47DA-95CA-C5AB0DC85B11", key_b64);
+
        SHA1((unsigned char *)buf, n, (unsigned char *)hash);
 
        lws_b64_encode_string(hash, 20,

diff --git a/lib/server-handshake.c b/lib/server-handshake.c
index ba52037..627fb31 100644 (file)
--- a/lib/server-handshake.c
+++ b/lib/server-handshake.c
@@ -56,14 +56,11 @@ handshake_0405(struct libwebsocket_context *context, struct libwebsocket *wsi)
                goto bail;
        }
 
-       // TODO: Use a truly platform independent snprintf implementation isntead! http://www.ijs.si/software/snprintf/ maybe?
-       #ifdef WIN32
-       n = _snprintf(
-       #else
-       n = snprintf(
-       #endif
-               (char *)context->service_buffer,
-                       sizeof(context->service_buffer),
+       /*
+        * since key length is restricted above (currently 128), cannot
+        * overflow
+        */
+       n = sprintf((char *)context->service_buffer,
                                "%s258EAFA5-E914-47DA-95CA-C5AB0DC85B11",
                                lws_hdr_simple_ptr(wsi, WSI_TOKEN_KEY));