1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
// $Id$
/*
In client_handler.h I alluded to the fact that we'll mess around with a
Client_Acceptor pointer. To do so, we need the Client_Acceptor object
declaration.
We know that including client_handler.h is redundant because
client_acceptor.h includes it. Still, the sentry prevents double-inclusion
from causing problems and it's sometimes good to be explicit about what
we're using.
On the other hand, we don't directly include any ACE header files here.
*/
#include "client_acceptor.h"
#include "client_handler.h"
/*
Our constructor doesn't do anything. That's generally a good idea. Unless
you want to start throwing exceptions, there isn't a really good way to
indicate that a constructor has failed. If I had my way, I'd have a boolean
return code from it that would cause new to return 0 if I failed. Oh
well...
*/
Client_Handler::Client_Handler (void)
{
}
/*
Our destructor doesn't do anything either. That is also by design.
Remember, we really want folks to use destroy() to get rid of us. If that's
so, then there's nothing left to do when the destructor gets invoked.
*/
Client_Handler::~Client_Handler (void)
{
}
/*
The much talked about destroy() method! The reason I keep going on about
this is because it's just a Bad Idea (TM) to do real work inside of a
destructor. Although this method is void, it really should return
int so that it can tell the caller there was a problem. Even as
void you could at least throw an exception which you would never want
to do in a destructor.
*/
void Client_Handler::destroy (void)
{
/*
We probably got here because of an error on the stream, so the peer
connection is probably already closed. Still... there are other ways to
get here and closing a closed peer doesn't hurt.
*/
this->peer ().close ();
/*
Tell the reactor to forget all about us. Notice that we use the same args
here that we use in the open() method to register ourselves. In addition,
we use the DONT_CALL flag to prevent handle_close() being called. Since we
likely got here due to handle_close(), that could cause a bit of nasty
recursion!
*/
this->reactor ()->remove_handler (this,
ACE_Event_Handler:: READ_MASK | ACE_Event_Handler::DONT_CALL);
/*
This is how we're able to tell folks not to use delete. By
deleting our own instance, we take care of memory leaks after ensuring
that the object is shut down correctly.
*/
delete this;
}
/*
As mentioned before, the open() method is called by the Client_Acceptor when
a new client connection has been accepted. The Client_Acceptor instance
pointer is cast to a void* and given to us here. We'll use that to avoid
some global data...
*/
int Client_Handler::open (void *_acceptor)
{
/*
Convert the void* to a Client_Acceptor*. You should probably use those
fancy new C++ cast operators but I can never remember how/when to do so.
Since you can cast just about anything around a void* without compiler
warnings be very sure of what you're doing when you do this kind of thing.
That's where the new-style cast operators can save you.
*/
Client_Acceptor *acceptor = (Client_Acceptor *) _acceptor;
/*
Our reactor reference will be set when we register ourselves but I decided
to go ahead and set it here. No good reason really...
*/
this->reactor (acceptor->reactor ());
/*
We need this to store the address of the client that we are now connected
to. We'll use it later to display a debug message.
*/
ACE_INET_Addr addr;
/*
Our ACE_Svc_Handler baseclass gives us the peer() method as a way to
access our underlying ACE_SOCK_Stream. On that object, we can invoke the
get_remote_addr() method to get get an ACE_INET_Addr having our client's
address information. As with most ACE methods, we'll get back (and return)
a -1 if there was any kind of error. Once we have the ACE_INET_Addr, we
can query it to find out the clien's host name, TCP/IP address, TCP/IP
port value and so forth. One word of warning: the get_host_name()
method of ACE_INET_Addr may return you an empty string if your name server
can't resolve it. On the other hand, get_host_addr() will always give you
the dotted-decimal string representing the TCP/IP address.
*/
if (this->peer ().get_remote_addr (addr) == -1)
{
return -1;
}
/*
If we managed to get the client's address then we're connected to a real
and valid client. I suppose that in some cases, the client may connect
and disconnect so quickly that it is invalid by the time we get here. In
any case, the test above should always be done to ensure that the
connection is worth keeping.
Now, regiser ourselves with a reactor and tell that reactor that we want
to be notified when there is something to read. Remember, we took our
reactor value from the acceptor which created us in the first place.
Since we're exploring a single-threaded implementation, this is the
correct thing to do.
*/
if (this->reactor ()->register_handler (this, ACE_Event_Handler::READ_MASK) == -1)
{
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) can't register with reactor\n"), -1);
}
/*
Here, we use the ACE_INET_Addr object to print a message with the name of
the client we're connected to. Again, it is possible that you'll get an
empty string for the host name if your DNS isn't configured correctly or
if there is some other reason that a TCP/IP addreess cannot be converted
into a host name.
*/
ACE_DEBUG ((LM_DEBUG, "(%P|%t) connected with %s\n", addr.get_host_name ()));
/*
Always return zero on success.
*/
return 0;
}
/*
In the open() method, we registered with the reactor and requested to be
notified when there is data to be read. When the reactor sees that activity
it will invoke this handle_input() method on us. As I mentioned, the _handle
parameter isn't useful to us but it narrows the list of methods the reactor
has to worry about and the list of possible virtual functions we would have
to override.
*/
int Client_Handler::handle_input (ACE_HANDLE _handle)
{
/*
Some compilers don't like it when you fail to use a parameter. This macro
will keep 'em quiet for you.
*/
ACE_UNUSED_ARG (_handle);
/*
Now, we create and initialize a buffer for receiving the data. Since this
is just a simple test app, we'll use a small buffer size.
*/
char buf[128];
memset (buf, 0, sizeof (buf));
/*
Invoke the process() method with a pointer to our data area. We'll let
that method worry about interfacing with the data. You might choose to go
ahead and read the data and then pass the result to process(). However,
application logic may require that you read a few bytes to determine what
else to read... It's best if we push that all into the application-logic
level.
*/
return this->process (buf, sizeof (buf));
}
/*
If we return -1 out of handle_input() or if the reactor sees other problems
with us then handle_close() will be called. It uses our destroy() method to
shut us down cleanly and get rid of our instance.
*/
int Client_Handler::handle_close (ACE_HANDLE _handle, ACE_Reactor_Mask _mask)
{
ACE_UNUSED_ARG (_handle);
ACE_UNUSED_ARG (_mask);
this->destroy ();
return 0;
}
/*
And, at last, we get to the application-logic level. Out of everything
we've done so far, this is the only thing that really has anything to do
with what your application will do. In this method we will read and process
the client's data. In a real appliation, you will probably have a bit more
in main() to deal with command line options but after that point, all of the
action takes place here.
*/
int Client_Handler::process (char *_rdbuf, int _rdbuf_len)
{
/*
Using the buffer provided for us, we read the data from the client. If
there is a read error (eg -- recv() returns -1) then it's a pretty good
bet that the connection is gone. Likewise, if we read zero bytes then
something wrong has happened. The reactor wouldn't have called us if
there wasn't some kind of read activity but there wouldn't be activity if
there were no bytes to read...
On the other hand, if we got some data then we can display it in a debug
message for everyone to see.
*/
switch (this->peer ().recv (_rdbuf, _rdbuf_len))
{
case -1:
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) %p bad read\n", "client"), -1);
case 0:
ACE_ERROR_RETURN ((LM_ERROR, "(%P|%t) closing daemon (fd = %d)\n", this->get_handle ()), -1);
default:
ACE_DEBUG ((LM_DEBUG, "(%P|%t) from client: %s", _rdbuf));
}
return 0;
}
|