apply changes from graingert#23

- use sendall() instead of send()
- allow custom max_buffer_size
- set socket timeout before connect

Thanks to @mrname

Author: stringfellow

clammy/__init__.py

@@ -36,13 +36,16 @@ def _init_socket(self):
         try:
             self.clamd_socket = socket.socket(self.socket_type, socket.SOCK_STREAM)
 
+            # Set timeout prior to connecting to ensure that an initial
+            # connection timeout will respect the setting regardless of OS.
+            # https://docs.python.org/3/library/socket.html#timeouts-and-the-connect-method
+            self.clamd_socket.settimeout(self.timeout)
+
             if self.socket_type == socket.AF_INET:
                 self.clamd_socket.connect((self.host, self.port))
             elif self.socket_type == socket.AF_UNIX:
                 self.clamd_socket.connect(self.unix_socket)
 
-            self.clamd_socket.settimeout(self.timeout)
-
         except socket.error:
             if self.socket_type == socket.AF_UNIX:
                 error_message = f'Error connecting to Unix socket "{self.unix_socket}"'
@@ -129,11 +132,13 @@ def _file_system_scan(self, command, file):
         finally:
             self._close_socket()
 
-    def instream(self, buff):
+    def instream(self, buff, max_chunk_size=1024):
         """
         Scan a buffer
 
         buff  filelikeobj: buffer to scan
+        max_chunk_size int: Maximum size of chunk to send to clamd in bytes
+          MUST be < StreamMaxLength in /etc/clamav/clamd.conf
 
         return:
           - (dict): {filename1: ("virusname", "status")}
@@ -147,15 +152,13 @@ def instream(self, buff):
             self._init_socket()
             self._send_command("INSTREAM")
 
-            max_chunk_size = 1024  # MUST be < StreamMaxLength in /etc/clamav/clamd.conf
-
             chunk = buff.read(max_chunk_size)
             while chunk:
                 size = struct.pack(b"!L", len(chunk))
-                self.clamd_socket.send(size + chunk)
+                self.clamd_socket.sendall(size + chunk)
                 chunk = buff.read(max_chunk_size)
 
-            self.clamd_socket.send(struct.pack(b"!L", 0))
+            self.clamd_socket.sendall(struct.pack(b"!L", 0))
 
             result = self._recv_response()
 
@@ -195,7 +198,7 @@ def _send_command(self, cmd, *args):
 
         # cmd = 'n{cmd}{args}\n'.format(cmd=cmd, args=concat_args).encode('utf-8')
         cmd = f"n{cmd}{concat_args}\n".encode("utf-8")
-        self.clamd_socket.send(cmd)
+        self.clamd_socket.sendall(cmd)
 
     def _recv_response(self):
         """