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1 /*
2  * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
3  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 #ifndef EVENT2_LISTENER_H_INCLUDED_
28 #define EVENT2_LISTENER_H_INCLUDED_
29 
30 #include <event2/visibility.h>
31 
32 #ifdef __cplusplus
33 extern "C" {
34 #endif
35 
36 #include <event2/event.h>
37 
38 struct sockaddr;
39 struct evconnlistener;
40 
41 /**
42    A callback that we invoke when a listener has a new connection.
43 
44    @param listener The evconnlistener
45    @param fd The new file descriptor
46    @param addr The source address of the connection
47    @param socklen The length of addr
48    @param user_arg the pointer passed to evconnlistener_new()
49  */
50 typedef void (*evconnlistener_cb)(struct evconnlistener *, evutil_socket_t, struct sockaddr *, int socklen, void *);
51 
52 /**
53    A callback that we invoke when a listener encounters a non-retriable error.
54 
55    @param listener The evconnlistener
56    @param user_arg the pointer passed to evconnlistener_new()
57  */
58 typedef void (*evconnlistener_errorcb)(struct evconnlistener *, void *);
59 
60 /** Flag: Indicates that we should not make incoming sockets nonblocking
61  * before passing them to the callback. */
62 #define LEV_OPT_LEAVE_SOCKETS_BLOCKING	(1u<<0)
63 /** Flag: Indicates that freeing the listener should close the underlying
64  * socket. */
65 #define LEV_OPT_CLOSE_ON_FREE		(1u<<1)
66 /** Flag: Indicates that we should set the close-on-exec flag, if possible */
67 #define LEV_OPT_CLOSE_ON_EXEC		(1u<<2)
68 /** Flag: Indicates that we should disable the timeout (if any) between when
69  * this socket is closed and when we can listen again on the same port. */
70 #define LEV_OPT_REUSEABLE		(1u<<3)
71 /** Flag: Indicates that the listener should be locked so it's safe to use
72  * from multiple threadcs at once. */
73 #define LEV_OPT_THREADSAFE		(1u<<4)
74 /** Flag: Indicates that the listener should be created in disabled
75  * state. Use evconnlistener_enable() to enable it later. */
76 #define LEV_OPT_DISABLED		(1u<<5)
77 /** Flag: Indicates that the listener should defer accept() until data is
78  * available, if possible.  Ignored on platforms that do not support this.
79  *
80  * This option can help performance for protocols where the client transmits
81  * immediately after connecting.  Do not use this option if your protocol
82  * _doesn't_ start out with the client transmitting data, since in that case
83  * this option will sometimes cause the kernel to never tell you about the
84  * connection.
85  *
86  * This option is only supported by evconnlistener_new_bind(): it can't
87  * work with evconnlistener_new_fd(), since the listener needs to be told
88  * to use the option before it is actually bound.
89  */
90 #define LEV_OPT_DEFERRED_ACCEPT		(1u<<6)
91 /** Flag: Indicates that we ask to allow multiple servers (processes or
92  * threads) to bind to the same port if they each set the option.
93  *
94  * SO_REUSEPORT is what most people would expect SO_REUSEADDR to be, however
95  * SO_REUSEPORT does not imply SO_REUSEADDR.
96  *
97  * This is only available on Linux and kernel 3.9+
98  */
99 #define LEV_OPT_REUSEABLE_PORT		(1u<<7)
100 /** Flag: Indicates that the listener wants to work only in IPv6 socket.
101  *
102  * According to RFC3493 and most Linux distributions, default value is to
103  * work in IPv4-mapped mode. If there is a requirement to bind same port
104  * on same ip addresses but different handlers for both IPv4 and IPv6,
105  * it is required to set IPV6_V6ONLY socket option to be sure that the
106  * code works as expected without affected by bindv6only sysctl setting in
107  * system.
108  *
109  * This socket option also supported by Windows.
110  */
111 #define LEV_OPT_BIND_IPV6ONLY		(1u<<8)
112 
113 /**
114    Allocate a new evconnlistener object to listen for incoming TCP connections
115    on a given file descriptor.
116 
117    @param base The event base to associate the listener with.
118    @param cb A callback to be invoked when a new connection arrives.  If the
119       callback is NULL, the listener will be treated as disabled until the
120       callback is set.
121    @param ptr A user-supplied pointer to give to the callback.
122    @param flags Any number of LEV_OPT_* flags
123    @param backlog Passed to the listen() call to determine the length of the
124       acceptable connection backlog.  Set to -1 for a reasonable default.
125       Set to 0 if the socket is already listening.
126    @param fd The file descriptor to listen on.  It must be a nonblocking
127       file descriptor, and it should already be bound to an appropriate
128       port and address.
129 */
130 EVENT2_EXPORT_SYMBOL
131 struct evconnlistener *evconnlistener_new(struct event_base *base,
132     evconnlistener_cb cb, void *ptr, unsigned flags, int backlog,
133     evutil_socket_t fd);
134 /**
135    Allocate a new evconnlistener object to listen for incoming TCP connections
136    on a given address.
137 
138    @param base The event base to associate the listener with.
139    @param cb A callback to be invoked when a new connection arrives. If the
140       callback is NULL, the listener will be treated as disabled until the
141       callback is set.
142    @param ptr A user-supplied pointer to give to the callback.
143    @param flags Any number of LEV_OPT_* flags
144    @param backlog Passed to the listen() call to determine the length of the
145       acceptable connection backlog.  Set to -1 for a reasonable default.
146    @param addr The address to listen for connections on.
147    @param socklen The length of the address.
148  */
149 EVENT2_EXPORT_SYMBOL
150 struct evconnlistener *evconnlistener_new_bind(struct event_base *base,
151     evconnlistener_cb cb, void *ptr, unsigned flags, int backlog,
152     const struct sockaddr *sa, int socklen);
153 /**
154    Disable and deallocate an evconnlistener.
155  */
156 EVENT2_EXPORT_SYMBOL
157 void evconnlistener_free(struct evconnlistener *lev);
158 /**
159    Re-enable an evconnlistener that has been disabled.
160  */
161 EVENT2_EXPORT_SYMBOL
162 int evconnlistener_enable(struct evconnlistener *lev);
163 /**
164    Stop listening for connections on an evconnlistener.
165  */
166 EVENT2_EXPORT_SYMBOL
167 int evconnlistener_disable(struct evconnlistener *lev);
168 
169 /** Return an evconnlistener's associated event_base. */
170 EVENT2_EXPORT_SYMBOL
171 struct event_base *evconnlistener_get_base(struct evconnlistener *lev);
172 
173 /** Return the socket that an evconnlistner is listening on. */
174 EVENT2_EXPORT_SYMBOL
175 evutil_socket_t evconnlistener_get_fd(struct evconnlistener *lev);
176 
177 /** Change the callback on the listener to cb and its user_data to arg.
178  */
179 EVENT2_EXPORT_SYMBOL
180 void evconnlistener_set_cb(struct evconnlistener *lev,
181     evconnlistener_cb cb, void *arg);
182 
183 /** Set an evconnlistener's error callback. */
184 EVENT2_EXPORT_SYMBOL
185 void evconnlistener_set_error_cb(struct evconnlistener *lev,
186     evconnlistener_errorcb errorcb);
187 
188 #ifdef __cplusplus
189 }
190 #endif
191 
192 #endif
193