Parser body_limit is optional (API Change):

API Changes:

The signature of basic_parser<>::body_limit(n) has changed. It now accepts an
optional std::uint64_t. The caller may indicate that no body limit is required
by calling body_limit(boost::none). The default limits remain in place in order
to maintain 'safe by default' behaviour.

closes #1897
closes #1965

CHANGELOG.md

@@ -1,9 +1,15 @@
+* Parser body_limit is optional (API Change)
 * Fix basic_stream expires_after (API Change)
 * Fix FILE namespace qualification
 
 API Changes:
 
-basic_stream::expires_after used to take a nanosecond duration type argument. This
+* The signature of basic_parser<>::body_limit(n) has changed. It now accepts an
+optional std::uint64_t. The caller may indicate that no body limit is required
+by calling body_limit(boost::none). The default limits remain in place in order
+to maintain 'safe by default' behaviour.
+
+* basic_stream::expires_after used to take a nanosecond duration type argument. This
 required users on systems where the steady_clock::duration_type was less accurate
 to explicity duration_cast when calling this function, making code non-portable.
 The duration type is now that of the embedded steady_clock.

include/boost/beast/http/basic_parser.hpp

@@ -69,8 +69,9 @@ template<bool isRequest>
 class basic_parser
     : private detail::basic_parser_base
 {
-    std::uint64_t body_limit_ =
-        default_body_limit(is_request{});   // max payload body
+    boost::optional<std::uint64_t>
+        body_limit_ =
+            default_body_limit(is_request{});   // max payload body
     std::uint64_t len_ = 0;                 // size of chunk or body
     std::uint64_t len0_ = 0;                // content length if known
     std::unique_ptr<char[]> buf_;           // temp storage
@@ -289,10 +290,11 @@ public:
 
         The default limit is 1MB for requests and 8MB for responses.
 
-        @param v The payload body limit to set
+        @param v An optional integral value representing the body limit.
+        If this is equal to `boost::none`, then the body limit is disabled.
     */
     void
-    body_limit(std::uint64_t v)
+    body_limit(boost::optional<std::uint64_t> v)
     {
         body_limit_ = v;
     }

include/boost/beast/http/impl/basic_parser.ipp

@@ -573,12 +573,15 @@ basic_parser<isRequest>::
 parse_body_to_eof(char const*& p,
     std::size_t n, error_code& ec)
 {
-    if(n > body_limit_)
+    if(body_limit_.has_value())
     {
-        ec = error::body_limit;
-        return;
+        if (n > *body_limit_)
+        {
+            ec = error::body_limit;
+            return;
+        }
+        *body_limit_ -= n;
     }
-    body_limit_ = body_limit_ - n;
     ec = {};
     n = this->on_body_impl(string_view{p, n}, ec);
     p += n;
@@ -648,12 +651,15 @@ parse_chunk_header(char const*& p0,
         }
         if(size != 0)
         {
-            if(size > body_limit_)
+            if (body_limit_.has_value())
             {
-                ec = error::body_limit;
-                return;
+                if (size > *body_limit_)
+                {
+                    ec = error::body_limit;
+                    return;
+                }
+                *body_limit_ -= size;
             }
-            body_limit_ -= size;
             auto const start = p;
             parse_chunk_extensions(p, pend, ec);
             if(ec)

test/beast/http/basic_parser.cpp

@@ -17,6 +17,7 @@
 #include <boost/beast/core/buffers_cat.hpp>
 #include <boost/beast/core/buffers_prefix.hpp>
 #include <boost/beast/core/buffers_suffix.hpp>
+#include <boost/beast/core/flat_buffer.hpp>
 #include <boost/beast/core/multi_buffer.hpp>
 #include <boost/beast/core/ostream.hpp>
 #include <boost/beast/http/parser.hpp>
@@ -1378,6 +1379,127 @@ public:
         BEAST_EXPECT(p.is_done());
     }
 
+    void
+    testChunkedOverflow()
+    {
+        {
+            const std::string hdr =
+                "HTTP/1.1 200 OK" "\r\n"
+                "Server: test" "\r\n"
+                "Transfer-Encoding: chunked" "\r\n"
+                "\r\n";
+            const std::string chunk1 =
+                "10000000000000000" "\r\n"
+                "data...";
+            test_parser<false> p;
+            error_code ec;
+            p.put(net::buffer(hdr), ec);
+            BEAST_EXPECT(!ec);
+            BEAST_EXPECT(p.is_header_done());
+            auto bt = p.put(net::buffer(chunk1), ec);
+            BEAST_EXPECT(bt == 0);
+            BEAST_EXPECT(ec == error::bad_chunk);
+        }
+        {
+            const std::string hdr =
+                "HTTP/1.1 200 OK" "\r\n"
+                "Server: test" "\r\n"
+                "Transfer-Encoding: chunked" "\r\n"
+                "\r\n"
+                "1" "\r\n"
+                "x" "\r\n";
+            const std::string chunk2 =
+                "FFFFFFFFFFFFFFFF" "\r\n"
+                "data...";
+            test_parser<false> p;
+            p.eager(true);
+            error_code ec;
+            flat_buffer fb;
+            fb.commit(net::buffer_copy(fb.prepare(10000), net::buffer(hdr)));
+            fb.consume(p.put(fb.data(), ec));
+            BEAST_EXPECT(p.is_header_done());
+            BEAST_EXPECT(ec = error::need_more);
+            fb.commit(net::buffer_copy(fb.prepare(10000), net::buffer(chunk2)));
+            auto bt = p.put(fb.data(), ec);
+            BEAST_EXPECT(bt == 0);
+            BEAST_EXPECT(ec == error::body_limit);
+        }
+        {
+            const std::string hdr =
+                "HTTP/1.1 200 OK" "\r\n"
+                "Server: test" "\r\n"
+                "Transfer-Encoding: chunked" "\r\n"
+                "\r\n"
+                "1" "\r\n"
+                "x" "\r\n";
+            const std::string chunk2 =
+                "FFFFFFFFFFFFFFFF" "\r\n"
+                "data...";
+            test_parser<false> p;
+            p.eager(true);
+            p.body_limit(boost::none);
+            error_code ec;
+            flat_buffer fb;
+            fb.commit(net::buffer_copy(fb.prepare(10000), net::buffer(hdr)));
+            fb.consume(p.put(fb.data(), ec));
+            BEAST_EXPECT(p.is_header_done());
+            BEAST_EXPECTS(ec = error::need_more, ec.message());
+            fb.commit(net::buffer_copy(fb.prepare(10000), net::buffer(chunk2)));
+            auto bt = p.put(fb.data(), ec);
+            BEAST_EXPECT(bt == 27);
+            BEAST_EXPECT(!ec);
+        }
+    }
+
+    void testChunkedBodySize()
+    {
+        string_view resp =
+            "HTTP/1.1 200 OK\r\n"
+            "Server: test\r\n"
+            "Transfer-Encoding: chunked\r\n"
+            "\r\n"
+
+            // chunk 1
+            "4\r\n"
+            "Wiki\r\n"
+
+            // chunk 2
+            "5\r\n"
+            "pedia\r\n"
+
+            // chunk 3
+            "E\r\n"
+            " in\r\n"
+            "\r\n"
+            "chunks.\r\n"
+
+            // end
+            "0\r\n"
+            "\r\n";
+
+        {  // body limit not exceeded
+            test_parser<false> p;
+            p.eager(true);
+            p.body_limit(23);
+            error_code ec;
+            p.put(net::buffer(resp.data(), resp.size()), ec);
+            BEAST_EXPECT(!ec);
+            p.put_eof(ec);
+            BEAST_EXPECT(!ec);
+        }
+
+        {  // body limit exceeded
+            test_parser<false> p;
+            p.eager(true);
+            p.body_limit(22);
+            error_code ec;
+            p.put(net::buffer(resp.data(), resp.size()), ec);
+            BEAST_EXPECT(ec == error::body_limit);
+            p.put_eof(ec);
+            BEAST_EXPECT(ec == error::partial_message);
+        }
+    }
+
     //--------------------------------------------------------------------------
 
     void
@@ -1404,6 +1526,8 @@ public:
         testRegression1();
         testIssue1211();
         testIssue1267();
+        testChunkedOverflow();
+        testChunkedBodySize();
     }
 };
 

test/beast/http/parser.cpp

@@ -18,7 +18,6 @@
 #include <boost/beast/core/flat_buffer.hpp>
 #include <boost/beast/core/multi_buffer.hpp>
 #include <boost/beast/core/ostream.hpp>
-#include <boost/beast/http/read.hpp>
 #include <boost/beast/http/string_body.hpp>
 #include <boost/system/system_error.hpp>
 #include <algorithm>