Refine FieldsReader concept (API Change)

* FieldsReader now requires chunked() and keep_alive()

* serializer logic calls into the reader to calculate
  the message metadata

* Removed some of the previous requirements of FieldsReader

Actions Required:

* Implement chunked() and keep_alive() for user defined FieldsReader types.

CHANGELOG.md

@@ -11,6 +11,7 @@ Version 62:
 API Changes:
 
 * parser requires basic_fields
+* Refine FieldsReader concept
 
 Actions Required:
 
@@ -18,6 +19,8 @@ Actions Required:
   will need to create their own subclass of basic_parser to work
   with their custom fields type.
 
+* Implement chunked() and keep_alive() for user defined FieldsReader types.
+
 --------------------------------------------------------------------------------
 
 Version 61:

doc/concept/Body.qbk

@@ -67,9 +67,10 @@ In this table:
 ]
 ]
 
-Exemplar:
+[heading Exemplar]
+
 ```
-struct body
+struct Body
 {
     using value_type = implementation_defined;
 

doc/concept/BodyReader.qbk

@@ -118,9 +118,10 @@ In this table:
     the implementation.
 ]
 
-Exemplar:
+[heading Exemplar]
+
 ```
-struct reader
+struct BodyReader
 {
 public:
     /** Controls when the implementation requests buffers.
@@ -140,7 +141,7 @@ public:
     */
     template<bool isRequest, class Body, class Headers>
     explicit
-    reader(message<isRequest, Body, Headers> const& msg);
+    BodyReader(message<isRequest, Body, Headers> const& msg);
 
     /** Initialization.
 

doc/concept/BodyWriter.qbk

@@ -94,9 +94,10 @@ In the table below:
     the implementation.
 ]
 
-Exemplar:
+[heading Exemplar]
+
 ```
-struct writer
+struct BodyWriter
 {
     /** Construct the writer.
 
@@ -104,7 +105,7 @@ struct writer
     */
     template<bool isRequest, class Body, class Fields>
     explicit
-    writer(message<isRequest, Body, Fields>& msg);
+    BodyWriter(message<isRequest, Body, Fields>& msg);
 
     /** Initialization.
 

doc/concept/Fields.qbk

@@ -33,24 +33,6 @@ In this table:
     [
         A type which meets the requirements of __FieldsReader__.
     ]
-][
-    [`c.has_close_impl()`]
-    [`bool`]
-    [
-        Returns `true` if the value for Connection has "close" in the list.
-    ]
-][
-    [`c.has_chunked_impl()`]
-    [`bool`]
-    [
-        Returns `true` if "chunked" is the last Transfer-Encoding.
-    ]
-][
-    [`c.has_content_length_impl()`]
-    [`bool`]
-    [
-        Returns `true` if the Content-Length field is present.
-    ]
 ][
     [`c.get_method_impl()`]
     [`string_view`]
@@ -109,4 +91,48 @@ In this table:
 ]
 ]
 
+[heading Exemplar]
+
+```
+class Fields
+{
+protected:
+    /** Set or clear the method string.
+
+        @note Only called for requests.
+    */
+    void set_method_impl(string_view s);
+
+    /** Set or clear the target string.
+
+        @note Only called for requests.
+    */
+    void set_target_impl(string_view s);
+
+    /** Set or clear the reason string.
+
+        @note Only called for responses.
+    */
+    void set_reason_impl(string_view s);
+
+    /** Returns the request-method string.
+
+        @note Only called for requests.
+    */
+    string_view get_method_impl() const;
+
+    /** Returns the request-target string.
+
+        @note Only called for requests.
+    */
+    string_view get_target_impl() const;
+
+    /** Returns the response reason-phrase string.
+
+        @note Only called for responses.
+    */
+    string_view get_reason_impl() const;
+};
+```
+
 [endsect]

doc/concept/FieldsReader.qbk

@@ -56,6 +56,27 @@ In this table:
         response. The lifetime of `f` is guaranteed
         to end no earlier than after the `X` is destroyed.
     ]
+][
+    [`a.chunked()`]
+    [`bool`]
+    [
+        Called once after construction, this function returns `true`
+        if the [*Transfer-Encoding] field is present, and the last
+        token in its value is [*"chunked"].
+    ]
+][
+    [`a.keep_alive()`]
+    [`bool`]
+    [
+        Called once after construction, this function returns `true`
+        if the semantics of the mesage indicate that the connection
+        should remain open after processing the message. When the
+        HTTP version is below 1.1, `keep_alive` returns `true` when
+        the [*Connection] field is present, and its value contains the
+        "keep-alive" token. Otherwise, `keep_alive` returns `true`
+        when either the [*Connection] field is absent, or if the
+        value does not contain the "close" token.
+    ]
 ][
     [`a.get()`]
     [X::const_buffers_type]
@@ -75,7 +96,8 @@ In this table:
 ]
 ]
 
-Exemplar:
+[heading Exemplar]
+
 ```
 struct FieldsReader
 {
@@ -88,6 +110,14 @@ struct FieldsReader
     // Constructor for responses
     FieldsReader(F const& f, unsigned version, unsigned status);
 
+    // Returns `true` if the payload uses the chunked Transfer-Encoding
+    bool
+    chunked();
+
+    // Returns `true` if keep-alive is indicated
+    bool
+    keep_alive();
+
     // Returns the serialized header buffers
     const_buffers_type
     get();

include/beast/http/fields.hpp

@@ -555,15 +555,6 @@ public:
     }
 
 protected:
-    /// Returns `true` if the value for Connection has "close" in the list.
-    bool has_close_impl() const;
-
-    /// Returns `true` if "chunked" is the last Transfer-Encoding
-    bool has_chunked_impl() const;
-
-    /// Returns `true` if the Content-Length field is present
-    bool has_content_length_impl() const;
-
     /** Set or clear the method string.
 
         @note Only called for requests.

include/beast/http/impl/fields.ipp

@@ -132,6 +132,12 @@ public:
         }
     };
 
+    bool
+    get_chunked() const;
+
+    bool
+    get_keep_alive(int version) const;
+
     template<class String>
     void
     prepare(String& s, basic_fields const& f,
@@ -146,6 +152,8 @@ public:
     static_string<max_static_start_line> ss_;
     string_view sv_;
     std::string s_;
+    bool chunked_;
+    bool keep_alive_;
 
 public:
     using const_buffers_type =
@@ -160,6 +168,18 @@ public:
     reader(basic_fields const& f,
         unsigned version, unsigned code);
 
+    bool
+    chunked()
+    {
+        return chunked_;
+    }
+
+    bool
+    keep_alive()
+    {
+        return keep_alive_;
+    }
+
     const_buffers_type
     get() const
     {
@@ -170,6 +190,41 @@ public:
     }
 };
 
+template<class Allocator>
+bool
+basic_fields<Allocator>::reader::
+get_chunked() const
+{
+    auto const te = token_list{
+        f_[field::transfer_encoding]};
+    for(auto it = te.begin(); it != te.end();)
+    {
+        auto next = std::next(it);
+        if(next == te.end())
+            return iequals(*it, "chunked");
+        it = next;
+    }
+    return false;
+}
+
+template<class Allocator>
+bool
+basic_fields<Allocator>::reader::
+get_keep_alive(int version) const
+{
+    if(version < 11)
+    {
+        auto const it = f_.find(field::connection);
+        if(it == f_.end())
+            return false;
+        return token_list{it->value()}.exists("keep-alive");
+    }
+    auto const it = f_.find(field::connection);
+    if(it == f_.end())
+        return true;
+    return ! token_list{it->value()}.exists("close");
+}
+
 template<class Allocator>
 template<class String>
 void
@@ -258,6 +313,8 @@ basic_fields<Allocator>::reader::
 reader(basic_fields const& f,
         unsigned version, verb v)
     : f_(f)
+    , chunked_(get_chunked())
+    , keep_alive_(get_keep_alive(version))
 {
     try
     {
@@ -276,6 +333,8 @@ basic_fields<Allocator>::reader::
 reader(basic_fields const& f,
         unsigned version, unsigned code)
     : f_(f)
+    , chunked_(get_chunked())
+    , keep_alive_(get_keep_alive(version))
 {
     try
     {
@@ -753,49 +812,6 @@ equal_range(string_view name) const ->
 
 // Fields
 
-template<class Allocator>
-bool
-basic_fields<Allocator>::
-has_close_impl() const
-{
-    auto const fit = set_.find(
-        to_string(field::connection), key_compare{});
-    if(fit == set_.end())
-        return false;
-    return token_list{fit->value()}.exists("close");
-}
-
-template<class Allocator>
-bool
-basic_fields<Allocator>::
-has_chunked_impl() const
-{
-    auto const fit = set_.find(to_string(
-        field::transfer_encoding), key_compare{});
-    if(fit == set_.end())
-        return false;
-    token_list const v{fit->value()};
-    auto it = v.begin();
-    if(it == v.end())
-        return false;
-    for(;;)
-    {
-        auto cur = it++;
-        if(it == v.end())
-            return iequals(*cur, "chunked");
-    }
-}
-
-template<class Allocator>
-bool
-basic_fields<Allocator>::
-has_content_length_impl() const
-{
-    auto const fit = set_.find(
-        to_string(field::content_length), key_compare{});
-    return fit != set_.end();
-}
-
 template<class Allocator>
 inline
 void

include/beast/http/impl/message.ipp

@@ -249,33 +249,6 @@ message(std::piecewise_construct_t,
 {
 }
 
-template<bool isRequest, class Body, class Fields>
-inline
-bool
-message<isRequest, Body, Fields>::
-has_close() const
-{
-    return this->has_close_impl();
-}
-
-template<bool isRequest, class Body, class Fields>
-inline
-bool
-message<isRequest, Body, Fields>::
-has_chunked() const
-{
-    return this->has_chunked_impl();
-}
-
-template<bool isRequest, class Body, class Fields>
-inline
-bool
-message<isRequest, Body, Fields>::
-has_content_length() const
-{
-    return this->has_content_length_impl();
-}
-
 template<bool isRequest, class Body, class Fields>
 boost::optional<std::uint64_t>
 message<isRequest, Body, Fields>::

include/beast/http/impl/serializer.ipp

@@ -59,10 +59,8 @@ get(error_code& ec, Visit&& visit)
     {
         frdinit(std::integral_constant<bool,
             isRequest>{});
-        close_ = m_.has_close() || (
+        close_ = ! frd_->keep_alive();
-            m_.version < 11 &&
+        if(frd_->chunked())
-            ! m_.has_content_length());
-        if(m_.has_chunked())
             goto go_init_c;
         s_ = do_init;
         BOOST_FALLTHROUGH;

include/beast/http/message.hpp

@@ -483,24 +483,6 @@ struct message : header<isRequest, Fields>
         return *this;
     }
 
-    /// Returns `true` if "close" is specified in the Connection field.
-    bool
-    has_close() const;
-
-    /// Returns `true` if "chunked" is the last Transfer-Encoding.
-    bool
-    has_chunked() const;
-
-    /** Returns `true` if the Content-Length field is present.
-
-        This function checks the fields to determine if the content
-        length field is present, regardless of the actual value.
-
-        @note The contents of the body payload are not inspected.
-    */
-    bool
-    has_content_length() const;
-
     /** Returns the payload size of the body in octets if possible.
 
         This function invokes the @b Body algorithm to measure

test/http/write.cpp

@@ -303,7 +303,10 @@ public:
     str(message<isRequest, Body, Fields> const& m)
     {
         test::string_ostream ss(ios_);
-        write(ss, m);
+        error_code ec;
+        write(ss, m, ec);
+        if(ec && ec != error::end_of_stream)
+            BOOST_THROW_EXCEPTION(system_error{ec});
         return ss.str;
     }
 
@@ -321,7 +324,7 @@ public:
             error_code ec;
             test::string_ostream ss{ios_};
             async_write(ss, m, do_yield[ec]);
-            if(BEAST_EXPECTS(! ec, ec.message()))
+            if(BEAST_EXPECTS(ec == error::end_of_stream, ec.message()))
                 BEAST_EXPECT(ss.str ==
                     "HTTP/1.0 200 OK\r\n"
                     "Server: test\r\n"
@@ -368,7 +371,8 @@ public:
             m.target("/");
             m.version = 10;
             m.insert(field::user_agent, "test");
-            m.insert("Content-Length", "5");
+            m.set(field::connection, "keep-alive");
+            m.set(field::content_length, "5");
             m.body = "*****";
             try
             {
@@ -376,6 +380,7 @@ public:
                 BEAST_EXPECT(fs.next_layer().str ==
                     "GET / HTTP/1.0\r\n"
                     "User-Agent: test\r\n"
+                    "Connection: keep-alive\r\n"
                     "Content-Length: 5\r\n"
                     "\r\n"
                     "*****"
@@ -465,7 +470,8 @@ public:
             m.target("/");
             m.version = 10;
             m.insert(field::user_agent, "test");
-            m.insert("Content-Length", "5");
+            m.set(field::connection, "keep-alive");
+            m.set(field::content_length, "5");
             m.body = "*****";
             error_code ec = test::error::fail_error;
             write(fs, m, ec);
@@ -474,6 +480,7 @@ public:
                 BEAST_EXPECT(fs.next_layer().str ==
                     "GET / HTTP/1.0\r\n"
                     "User-Agent: test\r\n"
+                    "Connection: keep-alive\r\n"
                     "Content-Length: 5\r\n"
                     "\r\n"
                     "*****"
@@ -493,7 +500,8 @@ public:
             m.target("/");
             m.version = 10;
             m.insert(field::user_agent, "test");
-            m.insert("Content-Length", "5");
+            m.set(field::connection, "keep-alive");
+            m.set(field::content_length, "5");
             m.body = "*****";
             error_code ec = test::error::fail_error;
             async_write(fs, m, do_yield[ec]);
@@ -502,6 +510,7 @@ public:
                 BEAST_EXPECT(fs.next_layer().str ==
                     "GET / HTTP/1.0\r\n"
                     "User-Agent: test\r\n"
+                    "Connection: keep-alive\r\n"
                     "Content-Length: 5\r\n"
                     "\r\n"
                     "*****"
@@ -858,10 +867,8 @@ public:
 
     void run() override
     {
-        yield_to([&](yield_context yield){
+        yield_to([&](yield_context yield){ testAsyncWrite(yield); });
-            testAsyncWrite(yield); });
+        yield_to([&](yield_context yield){ testFailures(yield); });
-        yield_to([&](yield_context yield){
-            testFailures(yield); });
         testOutput();
         test_std_ostream();
         testIoService();

test/websocket/stream.cpp

@@ -1004,7 +1004,7 @@ public:
                 }
             };
         // wrong version
-        check(error::handshake_failed,
+        check(http::error::end_of_stream,
             "GET / HTTP/1.0\r\n"
             "Host: localhost:80\r\n"
             "Upgrade: WebSocket\r\n"