2 * Networking abstraction in PuTTY.
4 * The way this works is: a back end can choose to open any number
5 * of sockets - including zero, which might be necessary in some.
6 * It can register a bunch of callbacks (most notably for when
7 * data is received) for each socket, and it can call the networking
8 * abstraction to send data without having to worry about blocking.
9 * The stuff behind the abstraction takes care of selects and
10 * nonblocking writes and all that sort of painful gubbins.
13 #ifndef PUTTY_NETWORK_H
14 #define PUTTY_NETWORK_H
16 typedef struct SockAddr_tag
*SockAddr
;
17 /* pay attention to levels of indirection */
18 typedef struct socket_function_table
**Socket
;
19 typedef struct plug_function_table
**Plug
;
21 struct socket_function_table
{
22 Plug(*plug
) (Socket s
, Plug p
);
23 /* use a different plug (return the old one) */
24 /* if p is NULL, it doesn't change the plug */
25 /* but it does return the one it's using */
26 void (*close
) (Socket s
);
27 int (*write
) (Socket s
, char *data
, int len
);
28 int (*write_oob
) (Socket s
, char *data
, int len
);
29 void (*flush
) (Socket s
);
30 void (*set_private_ptr
) (Socket s
, void *ptr
);
31 void *(*get_private_ptr
) (Socket s
);
32 void (*set_frozen
) (Socket s
, int is_frozen
);
33 /* ignored by tcp, but vital for ssl */
34 char *(*socket_error
) (Socket s
);
37 struct plug_function_table
{
39 (Plug p
, char *error_msg
, int error_code
, int calling_back
);
40 /* error_msg is NULL iff it is not an error (ie it closed normally) */
41 /* calling_back != 0 iff there is a Plug function */
42 /* currently running (would cure the fixme in try_send()) */
43 int (*receive
) (Plug p
, int urgent
, char *data
, int len
);
45 * - urgent==0. `data' points to `len' bytes of perfectly
48 * - urgent==1. `data' points to `len' bytes of data,
49 * which were read from before an Urgent pointer.
51 * - urgent==2. `data' points to `len' bytes of data,
52 * the first of which was the one at the Urgent mark.
54 void (*sent
) (Plug p
, int bufsize
);
56 * The `sent' function is called when the pending send backlog
57 * on a socket is cleared or partially cleared. The new backlog
58 * size is passed in the `bufsize' parameter.
60 int (*accepting
)(Plug p
, void *sock
);
62 * returns 0 if the host at address addr is a valid host for connecting or error
66 /* proxy indirection layer */
67 Socket
new_connection(SockAddr addr
, char *hostname
,
68 int port
, int privport
,
69 int oobinline
, int nodelay
, Plug plug
);
70 Socket
new_listener(int port
, Plug plug
, int local_host_only
);
72 /* socket functions */
74 void sk_init(void); /* called once at program startup */
75 void sk_cleanup(void); /* called just before program exit */
77 SockAddr
sk_namelookup(char *host
, char **canonicalname
);
78 void sk_getaddr(SockAddr addr
, char *buf
, int buflen
);
79 int sk_addrtype(SockAddr addr
);
80 void sk_addrcopy(SockAddr addr
, char *buf
);
81 void sk_addr_free(SockAddr addr
);
83 Socket
sk_new(SockAddr addr
, int port
, int privport
, int oobinline
,
86 Socket
sk_newlistener(int port
, Plug plug
, int local_host_only
);
88 Socket
sk_register(void *sock
, Plug plug
);
90 #define sk_plug(s,p) (((*s)->plug) (s, p))
91 #define sk_close(s) (((*s)->close) (s))
92 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
93 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
94 #define sk_flush(s) (((*s)->flush) (s))
96 #ifdef DEFINE_PLUG_METHOD_MACROS
97 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
98 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
99 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
100 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock))
104 * Each socket abstraction contains a `void *' private field in
105 * which the client can keep state.
107 * This is perhaps unnecessary now that we have the notion of a plug,
108 * but there is some existing code that uses it, so it stays.
110 #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr))
111 #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s))
114 * Special error values are returned from sk_namelookup and sk_new
115 * if there's a problem. These functions extract an error message,
116 * or return NULL if there's no problem.
118 char *sk_addr_error(SockAddr addr
);
119 #define sk_socket_error(s) (((*s)->socket_error) (s))
122 * Set the `frozen' flag on a socket. A frozen socket is one in
123 * which all READABLE notifications are ignored, so that data is
124 * not accepted from the peer until the socket is unfrozen. This
125 * exists for two purposes:
127 * - Port forwarding: when a local listening port receives a
128 * connection, we do not want to receive data from the new
129 * socket until we have somewhere to send it. Hence, we freeze
130 * the socket until its associated SSH channel is ready; then we
131 * unfreeze it and pending data is delivered.
133 * - Socket buffering: if an SSH channel (or the whole connection)
134 * backs up or presents a zero window, we must freeze the
135 * associated local socket in order to avoid unbounded buffer
138 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))
141 * Call this after an operation that might have tried to send on a
142 * socket, to clean up any pending network errors.
144 void net_pending_errors(void);
146 /********** SSL stuff **********/
149 * This section is subject to change, but you get the general idea
150 * of what it will eventually look like.
153 typedef struct certificate
*Certificate
;
154 typedef struct our_certificate
*Our_Certificate
;
155 /* to be defined somewhere else, somehow */
157 typedef struct ssl_client_socket_function_table
**SSL_Client_Socket
;
158 typedef struct ssl_client_plug_function_table
**SSL_Client_Plug
;
160 struct ssl_client_socket_function_table
{
161 struct socket_function_table base
;
162 void (*renegotiate
) (SSL_Client_Socket s
);
163 /* renegotiate the cipher spec */
166 struct ssl_client_plug_function_table
{
167 struct plug_function_table base
;
168 int (*refuse_cert
) (SSL_Client_Plug p
, Certificate cert
[]);
169 /* do we accept this certificate chain? If not, why not? */
170 /* cert[0] is the server's certificate, cert[] is NULL-terminated */
171 /* the last certificate may or may not be the root certificate */
172 Our_Certificate(*client_cert
) (SSL_Client_Plug p
);
173 /* the server wants us to identify ourselves */
174 /* may return NULL if we want anonymity */
177 SSL_Client_Socket
sk_ssl_client_over(Socket s
, /* pre-existing (tcp) connection */
180 #define sk_renegotiate(s) (((*s)->renegotiate) (s))