http_{request,response}_parser: Limit header length

Author: lhmouse

etc/poseidon/main.conf

@@ -98,6 +98,13 @@ network
     //   null  ::= use zlib default value
     default_compression_level = 8
 
+    // max_header_length:
+    //   [bytes]  ::= maximum number of bytes that the headers of a message,
+    //                including the request URI if any, is allowed to
+    //                contain
+    //   null     ::= default value: 256 KiB
+    max_header_length = 262144
+
     // max_request_content_length:
     //   [bytes]  ::= maximum number of bytes that the body of a request
     //                message from a client is allowed to contain (used by

poseidon/http/http_c_headers.cpp

@@ -12,6 +12,18 @@ HTTP_C_Headers::
   {
   }
 
+size_t
+HTTP_C_Headers::
+estimate_size()
+  const
+  {
+    size_t tlen = this->raw_host.size() + this->raw_userinfo.size()
+                  + this->raw_path.size() + this->raw_query.size();
+    for(const auto& hr : this->headers)
+      tlen += 4 + hr.first.length() + hr.second.as_string_length();
+    return tlen;
+  }
+
 void
 HTTP_C_Headers::
 encode_and_set_path(chars_view path)

poseidon/http/http_c_headers.hpp

@@ -64,6 +64,11 @@ struct HTTP_C_Headers
         this->headers.clear();
       }
 
+    // Estimates the number of bytes of all headers.
+    size_t
+    estimate_size()
+      const;
+
     // Encodes an arbitrary path and assigns it to `raw_path`.
     void
     encode_and_set_path(chars_view path);

poseidon/http/http_request_parser.cpp

@@ -19,6 +19,12 @@ HTTP_Request_Parser::s_settings[1] =
     // on_url
     +[](::http_parser* ps, const char* str, size_t len)
       {
+        // Append to the the URI.
+        if(this->m_headers.estimate_size() + len > this->m_max_header_length)
+          POSEIDON_THROW((
+              "HTTP header length limit exceeded: `$1` > `$2`"),
+              this->m_headers.estimate_size() + len, this->m_max_content_length);
+
         this->m_headers.raw_host.append(str, len);
         return 0;
       },
@@ -36,6 +42,11 @@ HTTP_Request_Parser::s_settings[1] =
 
         // Append the header name to the last key, as this callback might be
         // invoked repeatedly.
+        if(this->m_headers.estimate_size() + len > this->m_max_header_length)
+          POSEIDON_THROW((
+              "HTTP header length limit exceeded: `$1` > `$2`"),
+              this->m_headers.estimate_size() + len, this->m_max_content_length);
+
         this->m_headers.headers.mut_back().first.mut_str().append(str, len);
         return 0;
       },
@@ -44,6 +55,11 @@ HTTP_Request_Parser::s_settings[1] =
     +[](::http_parser* ps, const char* str, size_t len)
       {
         // Append the header value, as this callback might be invoked repeatedly.
+        if(this->m_headers.estimate_size() + len > this->m_max_header_length)
+          POSEIDON_THROW((
+              "HTTP header length limit exceeded: `$1` > `$2`"),
+              this->m_headers.estimate_size() + len, this->m_max_content_length);
+
         cow_string value = this->m_headers.headers.back().second.as_string();
         value.append(str, len);
         this->m_headers.headers.mut_back().second = move(value);
@@ -195,8 +211,10 @@ HTTP_Request_Parser()
     auto conf_file = main_config.copy();
     this->m_default_compression_level = static_cast<int>(conf_file.get_integer_opt(
                                 &"network.http.default_compression_level", 0, 9).value_or(6));
+    this->m_max_header_length = static_cast<uint32_t>(conf_file.get_integer_opt(
+                           &"network.http.max_header_length", 256, 16777216).value_or(262144));
     this->m_max_content_length = static_cast<uint32_t>(conf_file.get_integer_opt(
-                     &"network.http.max_request_content_length", 256, 16777216).value_or(1048576));
+                 &"network.http.max_request_content_length", 256, 16777216).value_or(1048576));
   }
 
 HTTP_Request_Parser::

poseidon/http/http_request_parser.hpp

@@ -13,6 +13,7 @@ class HTTP_Request_Parser
   {
   private:
     int m_default_compression_level;
+    uint32_t m_max_header_length;
     uint32_t m_max_content_length;
 
     static const ::http_parser_settings s_settings[1];
@@ -45,6 +46,11 @@ class HTTP_Request_Parser
       const noexcept
       { return this->m_default_compression_level;  }
 
+    uint32_t
+    max_header_length()
+      const noexcept
+      { return this->m_max_header_length;  }
+
     uint32_t
     max_content_length()
       const noexcept

poseidon/http/http_response_parser.cpp

@@ -37,6 +37,11 @@ HTTP_Response_Parser::s_settings[1] =
 
         // Append the header name to the last key, as this callback might be
         // invoked repeatedly.
+        if(this->m_headers.estimate_size() + len > this->m_max_header_length)
+          POSEIDON_THROW((
+              "HTTP header length limit exceeded: `$1` > `$2`"),
+              this->m_headers.estimate_size() + len, this->m_max_content_length);
+
         this->m_headers.headers.mut_back().first.mut_str().append(str, len);
         return 0;
       },
@@ -45,6 +50,11 @@ HTTP_Response_Parser::s_settings[1] =
     +[](::http_parser* ps, const char* str, size_t len)
       {
         // Append the header value, as this callback might be invoked repeatedly.
+        if(this->m_headers.estimate_size() + len > this->m_max_header_length)
+          POSEIDON_THROW((
+              "HTTP header length limit exceeded: `$1` > `$2`"),
+              this->m_headers.estimate_size() + len, this->m_max_content_length);
+
         cow_string value = this->m_headers.headers.back().second.as_string();
         value.append(str, len);
         this->m_headers.headers.mut_back().second = move(value);
@@ -101,8 +111,10 @@ HTTP_Response_Parser()
     auto conf_file = main_config.copy();
     this->m_default_compression_level = static_cast<int>(conf_file.get_integer_opt(
                                 &"network.http.default_compression_level", 0, 9).value_or(6));
+    this->m_max_header_length = static_cast<uint32_t>(conf_file.get_integer_opt(
+                           &"network.http.max_header_length", 256, 16777216).value_or(262144));
     this->m_max_content_length = static_cast<uint32_t>(conf_file.get_integer_opt(
-                     &"network.http.max_response_content_length", 256, 16777216).value_or(1048576));
+                &"network.http.max_response_content_length", 256, 16777216).value_or(1048576));
   }
 
 HTTP_Response_Parser::

poseidon/http/http_response_parser.hpp

@@ -13,6 +13,7 @@ class HTTP_Response_Parser
   {
   private:
     int m_default_compression_level;
+    uint32_t m_max_header_length;
     uint32_t m_max_content_length;
 
     static const ::http_parser_settings s_settings[1];
@@ -45,6 +46,11 @@ class HTTP_Response_Parser
       const noexcept
       { return this->m_default_compression_level;  }
 
+    uint32_t
+    max_header_length()
+      const noexcept
+      { return this->m_max_header_length;  }
+
     uint32_t
     max_content_length()
       const noexcept

poseidon/http/http_s_headers.cpp

@@ -12,6 +12,17 @@ HTTP_S_Headers::
   {
   }
 
+size_t
+HTTP_S_Headers::
+estimate_size()
+  const
+  {
+    size_t tlen = 12 + this->reason.size();
+    for(const auto& hr : this->headers)
+      tlen += 4 + hr.first.length() + hr.second.as_string_length();
+    return tlen;
+  }
+
 void
 HTTP_S_Headers::
 encode(tinyfmt& fmt)

poseidon/http/http_s_headers.hpp

@@ -45,6 +45,11 @@ struct HTTP_S_Headers
         this->headers.clear();
       }
 
+    // Estimates the number of bytes of all headers.
+    size_t
+    estimate_size()
+      const;
+
     // Encodes headers in wire format. Lines are separated by CR LF pairs. The
     // output will be suitable for sending through a stream socket.
     void