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
18 typedef struct config_tag Config;
19 typedef struct backend_tag Backend;
20 typedef struct terminal_tag Terminal;
23 typedef struct SockAddr_tag *SockAddr;
24 /* pay attention to levels of indirection */
25 typedef struct socket_function_table **Socket;
26 typedef struct plug_function_table **Plug;
28 struct socket_function_table {
29 Plug(*plug) (Socket s, Plug p);
30 /* use a different plug (return the old one) */
31 /* if p is NULL, it doesn't change the plug */
32 /* but it does return the one it's using */
33 void (*close) (Socket s);
34 int (*write) (Socket s, const char *data, int len);
35 int (*write_oob) (Socket s, const char *data, int len);
36 void (*flush) (Socket s);
37 void (*set_private_ptr) (Socket s, void *ptr);
38 void *(*get_private_ptr) (Socket s);
39 void (*set_frozen) (Socket s, int is_frozen);
40 /* ignored by tcp, but vital for ssl */
41 char *(*socket_error) (Socket s);
44 struct plug_function_table {
46 (Plug p, char *error_msg, int error_code, int calling_back);
47 /* error_msg is NULL iff it is not an error (ie it closed normally) */
48 /* calling_back != 0 iff there is a Plug function */
49 /* currently running (would cure the fixme in try_send()) */
50 int (*receive) (Plug p, int urgent, char *data, int len);
52 * - urgent==0. `data' points to `len' bytes of perfectly
55 * - urgent==1. `data' points to `len' bytes of data,
56 * which were read from before an Urgent pointer.
58 * - urgent==2. `data' points to `len' bytes of data,
59 * the first of which was the one at the Urgent mark.
61 void (*sent) (Plug p, int bufsize);
63 * The `sent' function is called when the pending send backlog
64 * on a socket is cleared or partially cleared. The new backlog
65 * size is passed in the `bufsize' parameter.
67 int (*accepting)(Plug p, void *sock);
69 * returns 0 if the host at address addr is a valid host for connecting or error
73 /* proxy indirection layer */
74 Socket new_connection(SockAddr addr, char *hostname,
75 int port, int privport,
76 int oobinline, int nodelay, Plug plug,
78 Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,
80 SockAddr name_lookup(char *host, int port, char **canonicalname,
83 /* socket functions */
85 void sk_init(void); /* called once at program startup */
86 void sk_cleanup(void); /* called just before program exit */
88 SockAddr sk_namelookup(const char *host, char **canonicalname);
89 SockAddr sk_nonamelookup(const char *host);
90 void sk_getaddr(SockAddr addr, char *buf, int buflen);
91 int sk_hostname_is_local(char *name);
92 int sk_address_is_local(SockAddr addr);
93 enum { ADDRTYPE_IPV4, ADDRTYPE_IPV6, ADDRTYPE_NAME };
94 int sk_addrtype(SockAddr addr);
95 void sk_addrcopy(SockAddr addr, char *buf);
96 void sk_addr_free(SockAddr addr);
98 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
101 Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only);
103 Socket sk_register(void *sock, Plug plug);
105 #define sk_plug(s,p) (((*s)->plug) (s, p))
106 #define sk_close(s) (((*s)->close) (s))
107 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
108 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
109 #define sk_flush(s) (((*s)->flush) (s))
111 #ifdef DEFINE_PLUG_METHOD_MACROS
112 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
113 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
114 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
115 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock))
119 * Each socket abstraction contains a `void *' private field in
120 * which the client can keep state.
122 * This is perhaps unnecessary now that we have the notion of a plug,
123 * but there is some existing code that uses it, so it stays.
125 #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr))
126 #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s))
129 * Special error values are returned from sk_namelookup and sk_new
130 * if there's a problem. These functions extract an error message,
131 * or return NULL if there's no problem.
133 char *sk_addr_error(SockAddr addr);
134 #define sk_socket_error(s) (((*s)->socket_error) (s))
137 * Set the `frozen' flag on a socket. A frozen socket is one in
138 * which all READABLE notifications are ignored, so that data is
139 * not accepted from the peer until the socket is unfrozen. This
140 * exists for two purposes:
142 * - Port forwarding: when a local listening port receives a
143 * connection, we do not want to receive data from the new
144 * socket until we have somewhere to send it. Hence, we freeze
145 * the socket until its associated SSH channel is ready; then we
146 * unfreeze it and pending data is delivered.
148 * - Socket buffering: if an SSH channel (or the whole connection)
149 * backs up or presents a zero window, we must freeze the
150 * associated local socket in order to avoid unbounded buffer
153 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))
156 * Call this after an operation that might have tried to send on a
157 * socket, to clean up any pending network errors.
159 void net_pending_errors(void);
162 * Simple wrapper on getservbyname(), needed by ssh.c. Returns the
163 * port number, in host byte order (suitable for printf and so on).
164 * Returns 0 on failure. Any platform not supporting getservbyname
165 * can just return 0 - this function is not required to handle
166 * numeric port specifications.
168 int net_service_lookup(char *service);
170 /********** SSL stuff **********/
173 * This section is subject to change, but you get the general idea
174 * of what it will eventually look like.
177 typedef struct certificate *Certificate;
178 typedef struct our_certificate *Our_Certificate;
179 /* to be defined somewhere else, somehow */
181 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
182 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
184 struct ssl_client_socket_function_table {
185 struct socket_function_table base;
186 void (*renegotiate) (SSL_Client_Socket s);
187 /* renegotiate the cipher spec */
190 struct ssl_client_plug_function_table {
191 struct plug_function_table base;
192 int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
193 /* do we accept this certificate chain? If not, why not? */
194 /* cert[0] is the server's certificate, cert[] is NULL-terminated */
195 /* the last certificate may or may not be the root certificate */
196 Our_Certificate(*client_cert) (SSL_Client_Plug p);
197 /* the server wants us to identify ourselves */
198 /* may return NULL if we want anonymity */
201 SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */
204 #define sk_renegotiate(s) (((*s)->renegotiate) (s))