FCGI: Fix connection handling on broken pipe: Reopen new socket

3 files changed, 57 insertions, 8 deletions

diff --git a/plugins/fcgi/fcgi.cpp b/plugins/fcgi/fcgi.cpp
index 5a7ce65..7748845 100644
--- a/plugins/fcgi/fcgi.cpp
+++ b/plugins/fcgi/fcgi.cpp
@@ -357,7 +357,7 @@ std::string fcgi_plugin::fcgiQuery(FCGIContext& context)
  std::lock_guard<std::mutex> socket_lock{socket->getMutex()};
 
  if (!socket->is_open()) {
-  //std::cout << "FCGI: Opening new socket" << std::endl;
+  std::cout << "FCGI: Opening new socket to " << app_addr << std::endl;
 
   socket->open();
   opening = true;
@@ -402,7 +402,12 @@ std::string fcgi_plugin::fcgiQuery(FCGIContext& context)
    std::cerr << "Warning: Not all bytes written" << std::endl;
  } catch (const fcgi_eof_error&) {
    std::cerr << "FCGI Error: EOF on write" << std::endl; // seems to be ok here
+   m_sockets.erase(app_addr); // force new socket next time
    return HttpStatus("500", "FCGI connection: EOF on write", context.SetResponseHeader);
+ } catch (const fcgi_broken_pipe_error&) {
+   std::cerr << "FCGI Error: Broken pipe on write" << std::endl; // seems to be ok here
+   m_sockets.erase(app_addr); // force new socket next time
+   return HttpStatus("500", "FCGI connection: Broken pipe on write", context.SetResponseHeader);
  }
 
 #if 0
@@ -418,7 +423,8 @@ std::string fcgi_plugin::fcgiQuery(FCGIContext& context)
   try {
    socket->read(inbuf);
   } catch (const fcgi_eof_error&) {
-   std::cerr << "FCGI Warning: Early EOF" << std::endl; // seems to be ok here
+   std::cerr << "FCGI Warning: Early EOF from application server. Break." << std::endl; // seems to be ok here
+   m_sockets.erase(app_addr); // force new socket next time
    ended = true;
    //return HttpStatus("500", "FCGI connection: EOF on read", context.SetResponseHeader);
   }
diff --git a/plugins/fcgi/socket.cpp b/plugins/fcgi/socket.cpp
index badcec6..82bb06b 100644
--- a/plugins/fcgi/socket.cpp
+++ b/plugins/fcgi/socket.cpp
@@ -81,11 +81,44 @@ void TCPSocket::open()
 
 bool TCPSocket::is_open()
 {
- return m_socket.is_open();
+ if (m_socket.is_open()) {
+  std::vector<char> inbuf;
+
+  int error;
+  socklen_t len = sizeof (error);
+  int retval {getsockopt(m_socket.native_handle(), SOL_SOCKET, SO_ERROR, &error, &len)};
+
+  if (retval) {
+   std::cerr << "FCGI Error: getsockopt() error in is_open(): " << strerror(errno) << std::endl;
+   try {
+    // for graceful shutdown, according to
+    // https://www.boost.org/doc/libs/1_66_0/doc/html/boost_asio/reference/basic_stream_socket/close/overload1.html
+    m_socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both);
+    m_socket.close(); // correct state
+   } catch (...) {
+    std::cerr << "Error on shutdown/close" << std::endl;
+   }
+   return false;
+  }
+
+  if (error != 0) {
+   try {
+    m_socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both);
+    m_socket.close(); // correct state
+   } catch (...) {
+    std::cerr << "Error on shutdown/close" << std::endl;
+   }
+   return false;
+  }
+
+  return true;
+ } else
+  return false;
 }
 
 void TCPSocket::close()
 {
+ m_socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both);
  m_socket.close();
 }
 
@@ -96,6 +129,8 @@ size_t TCPSocket::write(const std::vector<char>& data)
  } catch (const boost::system::system_error& ex) {
   if (ex.code() == boost::asio::error::eof) {
    throw fcgi_eof_error("EOF on write");
+  } else if (ex.code() == boost::asio::error::broken_pipe) {
+   throw fcgi_broken_pipe_error("Application server connection broken");
   } else
    throw std::runtime_error("FCGI Error: Unknown boost asio exception on write: "s + ex.what());
  } catch (const std::exception& ex) {
@@ -108,12 +143,12 @@ size_t TCPSocket::read(std::vector<char>& data)
  try {
   size_t result{0};
 
-  while (m_socket.available()) {
+  do {
    std::vector<char> inbuf_part(1024);
    size_t got { m_socket.read_some(boost::asio::buffer(inbuf_part))};
    data.insert(data.end(), inbuf_part.begin(), inbuf_part.begin() + got);
    result += got;
-  }
+  } while (m_socket.available());
 
   return result;
 
@@ -165,6 +200,8 @@ size_t FileSocket::write(const std::vector<char>& data)
  } catch (const boost::system::system_error& ex) {
   if (ex.code() == boost::asio::error::eof) {
    throw fcgi_eof_error("EOF on write");
+  } else if (ex.code() == boost::asio::error::broken_pipe) {
+   throw fcgi_broken_pipe_error("Application server connection broken");
   } else
    throw std::runtime_error("FCGI Error: Unknown boost asio exception on write: "s + ex.what());
  } catch (const std::exception& ex) {
@@ -176,13 +213,13 @@ size_t FileSocket::read(std::vector<char>& data)
 {
  try {
   size_t result{0};
-  
-  while (m_socket.available()) {
+
+  do { 
    std::vector<char> inbuf_part(1024);
    size_t got { m_socket.read_some(boost::asio::buffer(inbuf_part))};
    data.insert(data.end(), inbuf_part.begin(), inbuf_part.begin() + got);
    result += got;
-  }
+  } while (m_socket.available());
 
   return result;
  } catch (const boost::system::system_error& ex) {
diff --git a/plugins/fcgi/socket.h b/plugins/fcgi/socket.h
index 8fb5610..272b844 100644
--- a/plugins/fcgi/socket.h
+++ b/plugins/fcgi/socket.h
@@ -15,6 +15,12 @@ public:
  fcgi_eof_error(const std::string& what_arg): std::runtime_error(what_arg) {}
 };
 
+class fcgi_broken_pipe_error: public std::runtime_error
+{
+public:
+ fcgi_broken_pipe_error(const std::string& what_arg): std::runtime_error(what_arg) {}
+};
+
 class Socket
 {
  std::mutex m_mutex; // guard socket use in different threads