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 conf_tag Conf;
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 (*write_eof) (Socket s);
37 void (*flush) (Socket s);
38 void (*set_frozen) (Socket s, int is_frozen);
39 /* ignored by tcp, but vital for ssl */
40 const char *(*socket_error) (Socket s);
41 char *(*peer_info) (Socket s);
44 typedef union { void *p; int i; } accept_ctx_t;
45 typedef Socket (*accept_fn_t)(accept_ctx_t ctx, Plug plug);
47 struct plug_function_table {
48 void (*log)(Plug p, int type, SockAddr addr, int port,
49 const char *error_msg, int error_code);
51 * Passes the client progress reports on the process of setting
54 * - type==0 means we are about to try to connect to address
55 * `addr' (error_msg and error_code are ignored)
56 * - type==1 means we have failed to connect to address `addr'
57 * (error_msg and error_code are supplied). This is not a
58 * fatal error - we may well have other candidate addresses
59 * to fall back to. When it _is_ fatal, the closing()
60 * function will be called.
63 (Plug p, const char *error_msg, int error_code, int calling_back);
64 /* error_msg is NULL iff it is not an error (ie it closed normally) */
65 /* calling_back != 0 iff there is a Plug function */
66 /* currently running (would cure the fixme in try_send()) */
67 int (*receive) (Plug p, int urgent, char *data, int len);
69 * - urgent==0. `data' points to `len' bytes of perfectly
72 * - urgent==1. `data' points to `len' bytes of data,
73 * which were read from before an Urgent pointer.
75 * - urgent==2. `data' points to `len' bytes of data,
76 * the first of which was the one at the Urgent mark.
78 void (*sent) (Plug p, int bufsize);
80 * The `sent' function is called when the pending send backlog
81 * on a socket is cleared or partially cleared. The new backlog
82 * size is passed in the `bufsize' parameter.
84 int (*accepting)(Plug p, accept_fn_t constructor, accept_ctx_t ctx);
86 * `accepting' is called only on listener-type sockets, and is
87 * passed a constructor function+context that will create a fresh
88 * Socket describing the connection. It returns nonzero if it
89 * doesn't want the connection for some reason, or 0 on success.
93 /* proxy indirection layer */
94 /* NB, control of 'addr' is passed via new_connection, which takes
95 * responsibility for freeing it */
96 Socket new_connection(SockAddr addr, const char *hostname,
97 int port, int privport,
98 int oobinline, int nodelay, int keepalive,
99 Plug plug, Conf *conf);
100 Socket new_listener(const char *srcaddr, int port, Plug plug,
101 int local_host_only, Conf *conf, int addressfamily);
102 SockAddr name_lookup(const char *host, int port, char **canonicalname,
103 Conf *conf, int addressfamily);
104 int proxy_for_destination (SockAddr addr, const char *hostname, int port,
107 /* platform-dependent callback from new_connection() */
108 /* (same caveat about addr as new_connection()) */
109 Socket platform_new_connection(SockAddr addr, const char *hostname,
110 int port, int privport,
111 int oobinline, int nodelay, int keepalive,
112 Plug plug, Conf *conf);
114 /* socket functions */
116 void sk_init(void); /* called once at program startup */
117 void sk_cleanup(void); /* called just before program exit */
119 SockAddr sk_namelookup(const char *host, char **canonicalname, int address_family);
120 SockAddr sk_nonamelookup(const char *host);
121 void sk_getaddr(SockAddr addr, char *buf, int buflen);
122 int sk_addr_needs_port(SockAddr addr);
123 int sk_hostname_is_local(const char *name);
124 int sk_address_is_local(SockAddr addr);
125 int sk_address_is_special_local(SockAddr addr);
126 int sk_addrtype(SockAddr addr);
127 void sk_addrcopy(SockAddr addr, char *buf);
128 void sk_addr_free(SockAddr addr);
129 /* sk_addr_dup generates another SockAddr which contains the same data
130 * as the original one and can be freed independently. May not actually
131 * physically _duplicate_ it: incrementing a reference count so that
132 * one more free is required before it disappears is an acceptable
134 SockAddr sk_addr_dup(SockAddr addr);
136 /* NB, control of 'addr' is passed via sk_new, which takes responsibility
137 * for freeing it, as for new_connection() */
138 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
139 int nodelay, int keepalive, Plug p);
141 Socket sk_newlistener(const char *srcaddr, int port, Plug plug,
142 int local_host_only, int address_family);
144 #define sk_plug(s,p) (((*s)->plug) (s, p))
145 #define sk_close(s) (((*s)->close) (s))
146 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
147 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
148 #define sk_write_eof(s) (((*s)->write_eof) (s))
149 #define sk_flush(s) (((*s)->flush) (s))
151 #ifdef DEFINE_PLUG_METHOD_MACROS
152 #define plug_log(p,type,addr,port,msg,code) (((*p)->log) (p, type, addr, port, msg, code))
153 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
154 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
155 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
156 #define plug_accepting(p, constructor, ctx) (((*p)->accepting)(p, constructor, ctx))
160 * Special error values are returned from sk_namelookup and sk_new
161 * if there's a problem. These functions extract an error message,
162 * or return NULL if there's no problem.
164 const char *sk_addr_error(SockAddr addr);
165 #define sk_socket_error(s) (((*s)->socket_error) (s))
168 * Set the `frozen' flag on a socket. A frozen socket is one in
169 * which all READABLE notifications are ignored, so that data is
170 * not accepted from the peer until the socket is unfrozen. This
171 * exists for two purposes:
173 * - Port forwarding: when a local listening port receives a
174 * connection, we do not want to receive data from the new
175 * socket until we have somewhere to send it. Hence, we freeze
176 * the socket until its associated SSH channel is ready; then we
177 * unfreeze it and pending data is delivered.
179 * - Socket buffering: if an SSH channel (or the whole connection)
180 * backs up or presents a zero window, we must freeze the
181 * associated local socket in order to avoid unbounded buffer
184 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))
187 * Return a (dynamically allocated) string giving some information
188 * about the other end of the socket, suitable for putting in log
189 * files. May be NULL if nothing is available at all.
191 #define sk_peer_info(s) (((*s)->peer_info) (s))
194 * Simple wrapper on getservbyname(), needed by ssh.c. Returns the
195 * port number, in host byte order (suitable for printf and so on).
196 * Returns 0 on failure. Any platform not supporting getservbyname
197 * can just return 0 - this function is not required to handle
198 * numeric port specifications.
200 int net_service_lookup(char *service);
203 * Look up the local hostname; return value needs freeing.
206 char *get_hostname(void);
209 * Trivial socket implementation which just stores an error. Found in
212 Socket new_error_socket(const char *errmsg, Plug plug);
214 /********** SSL stuff **********/
217 * This section is subject to change, but you get the general idea
218 * of what it will eventually look like.
221 typedef struct certificate *Certificate;
222 typedef struct our_certificate *Our_Certificate;
223 /* to be defined somewhere else, somehow */
225 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
226 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
228 struct ssl_client_socket_function_table {
229 struct socket_function_table base;
230 void (*renegotiate) (SSL_Client_Socket s);
231 /* renegotiate the cipher spec */
234 struct ssl_client_plug_function_table {
235 struct plug_function_table base;
236 int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
237 /* do we accept this certificate chain? If not, why not? */
238 /* cert[0] is the server's certificate, cert[] is NULL-terminated */
239 /* the last certificate may or may not be the root certificate */
240 Our_Certificate(*client_cert) (SSL_Client_Plug p);
241 /* the server wants us to identify ourselves */
242 /* may return NULL if we want anonymity */
245 SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */
248 #define sk_renegotiate(s) (((*s)->renegotiate) (s))