Use static_string for WebSocket handshakes:

fix #328

This replaces usages of std::string with
static_string when performing WebSocket handshakes.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 * Refactor static_string
 * Refactor base64
+* Use static_string for WebSocket handshakes
 
 --------------------------------------------------------------------------------
 

include/beast/websocket/detail/hybi13.hpp

@@ -8,8 +8,10 @@
 #ifndef BEAST_WEBSOCKET_DETAIL_HYBI13_HPP
 #define BEAST_WEBSOCKET_DETAIL_HYBI13_HPP
 
+#include <beast/core/static_string.hpp>
 #include <beast/core/detail/base64.hpp>
 #include <beast/core/detail/sha1.hpp>
+#include <boost/assert.hpp>
 #include <boost/utility/string_ref.hpp>
 #include <array>
 #include <cstdint>
@@ -20,11 +22,17 @@ namespace beast {
 namespace websocket {
 namespace detail {
 
+using sec_ws_key_type = static_string<
+    beast::detail::base64::encoded_size(16)>;
+
+using sec_ws_accept_type = static_string<
+    beast::detail::base64::encoded_size(20)>;
+
 template<class Gen>
-std::string
+void
-make_sec_ws_key(Gen& g)
+make_sec_ws_key(sec_ws_key_type& key, Gen& g)
 {
-    std::array<std::uint8_t, 16> a;
+    char a[16];
     for(int i = 0; i < 16; i += 4)
     {
         auto const v = g();
@@ -33,24 +41,27 @@ make_sec_ws_key(Gen& g)
         a[i+2] = (v >> 16) & 0xff;
         a[i+3] = (v >> 24) & 0xff;
     }
-    return beast::detail::base64_encode(
+    key.resize(key.max_size());
-        a.data(), a.size());
+    key.resize(beast::detail::base64::encode(
+        key.data(), &a[0], 16));
 }
 
 template<class = void>
-std::string
+void
-make_sec_ws_accept(boost::string_ref const& key)
+make_sec_ws_accept(sec_ws_accept_type& accept,
+    boost::string_ref key)
 {
-    std::string s(key.data(), key.size());
+    BOOST_ASSERT(key.size() <= sec_ws_key_type::max_size_n);
-    s += "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+    static_string<sec_ws_key_type::max_size_n + 36> m(key);
+    m.append("258EAFA5-E914-47DA-95CA-C5AB0DC85B11");
     beast::detail::sha1_context ctx;
     beast::detail::init(ctx);
-    beast::detail::update(ctx, s.data(), s.size());
+    beast::detail::update(ctx, m.data(), m.size());
-    std::array<std::uint8_t,
+    char digest[beast::detail::sha1_context::digest_size];
-        beast::detail::sha1_context::digest_size> digest;
+    beast::detail::finish(ctx, &digest[0]);
-    beast::detail::finish(ctx, digest.data());
+    accept.resize(accept.max_size());
-    return beast::detail::base64_encode(
+    accept.resize(beast::detail::base64::encode(
-        digest.data(), digest.size());
+        accept.data(), &digest[0], sizeof(digest)));
 }
 
 } // detail

include/beast/websocket/impl/handshake.ipp

@@ -34,7 +34,7 @@ class stream<NextLayer>::handshake_op
         bool cont;
         stream<NextLayer>& ws;
         response_type* res_p;
-        std::string key;
+        detail::sec_ws_key_type key;
         request_type req;
         response_type res;
         int state = 0;

include/beast/websocket/impl/stream.ipp

@@ -134,7 +134,7 @@ do_handshake(response_type* res_p,
 {
     response_type res;
     reset();
-    std::string key;
+    detail::sec_ws_key_type key;
     {
         auto const req = build_request(
             key, host, resource, decorator);
@@ -155,7 +155,7 @@ template<class NextLayer>
 template<class Decorator>
 request_type
 stream<NextLayer>::
-build_request(std::string& key,
+build_request(detail::sec_ws_key_type& key,
     boost::string_ref const& host,
         boost::string_ref const& resource,
             Decorator const& decorator)
@@ -167,7 +167,7 @@ build_request(std::string& key,
     req.fields.insert("Host", host);
     req.fields.insert("Upgrade", "websocket");
     req.fields.insert("Connection", "upgrade");
-    key = detail::make_sec_ws_key(maskgen_);
+    detail::make_sec_ws_key(key, maskgen_);
     req.fields.insert("Sec-WebSocket-Key", key);
     req.fields.insert("Sec-WebSocket-Version", "13");
     if(pmd_opts_.client_enable)
@@ -186,6 +186,7 @@ build_request(std::string& key,
             req.fields, config);
     }
     decorator(req);
+    // VFALCO Use static_string here
     if(! req.fields.exists("User-Agent"))
         req.fields.insert("User-Agent",
             std::string("Beast/") + BEAST_VERSION_STRING);
@@ -203,6 +204,7 @@ build_response(request_type const& req,
         [&decorator](response_type& res)
         {
             decorator(res);
+            // VFALCO Use static_string here
             if(! res.fields.exists("Server"))
                 res.fields.insert("Server",
                     std::string("Beast/") +
@@ -235,6 +237,9 @@ build_response(request_type const& req,
         return err("Missing Sec-WebSocket-Key");
     if(! http::token_list{req.fields["Upgrade"]}.exists("websocket"))
         return err("Missing websocket Upgrade token");
+    auto const key = req.fields["Sec-WebSocket-Key"];
+    if(key.size() > detail::sec_ws_key_type::max_size_n)
+        return err("Invalid Sec-WebSocket-Key");
     {
         auto const version =
             req.fields["Sec-WebSocket-Version"];
@@ -255,6 +260,7 @@ build_response(request_type const& req,
             return res;
         }
     }
+
     response_type res;
     {
         detail::pmd_offer offer;
@@ -269,10 +275,9 @@ build_response(request_type const& req,
     res.fields.insert("Upgrade", "websocket");
     res.fields.insert("Connection", "upgrade");
     {
-        auto const key =
+        detail::sec_ws_accept_type accept;
-            req.fields["Sec-WebSocket-Key"];
+        detail::make_sec_ws_accept(accept, key);
-        res.fields.insert("Sec-WebSocket-Accept",
+        res.fields.insert("Sec-WebSocket-Accept", accept);
-            detail::make_sec_ws_accept(key));
     }
     decorate(res);
     return res;
@@ -282,7 +287,7 @@ template<class NextLayer>
 void
 stream<NextLayer>::
 do_response(http::response_header const& res,
-    boost::string_ref const& key, error_code& ec)
+    detail::sec_ws_key_type const& key, error_code& ec)
 {
     // VFALCO Review these error codes
     auto fail = [&]{ ec = error::response_failed; };
@@ -296,8 +301,10 @@ do_response(http::response_header const& res,
         return fail();
     if(! res.fields.exists("Sec-WebSocket-Accept"))
         return fail();
-    if(res.fields["Sec-WebSocket-Accept"] !=
+    detail::sec_ws_accept_type accept;
-        detail::make_sec_ws_accept(key))
+    detail::make_sec_ws_accept(accept, key);
+    if(accept.compare(
+            res.fields["Sec-WebSocket-Accept"]) != 0)
         return fail();
     detail::pmd_offer offer;
     pmd_read(offer, res.fields);

include/beast/websocket/stream.hpp

@@ -10,6 +10,7 @@
 
 #include <beast/config.hpp>
 #include <beast/websocket/option.hpp>
+#include <beast/websocket/detail/hybi13.hpp>
 #include <beast/websocket/detail/stream_base.hpp>
 #include <beast/http/message.hpp>
 #include <beast/http/string_body.hpp>
@@ -2981,7 +2982,7 @@ private:
 
     template<class Decorator>
     request_type
-    build_request(std::string& key,
+    build_request(detail::sec_ws_key_type& key,
         boost::string_ref const& host,
             boost::string_ref const& resource,
                 Decorator const& decorator);
@@ -2993,7 +2994,7 @@ private:
 
     void
     do_response(http::response_header const& resp,
-        boost::string_ref const& key, error_code& ec);
+        detail::sec_ws_key_type const& key, error_code& ec);
 };
 
 } // websocket