network.h

   1 /*
   2  * Networking abstraction in PuTTY.
   3  *
   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.
  11  */
  12
  13 #ifndef PUTTY_NETWORK_H
  14 #define PUTTY_NETWORK_H
  15
  16 #ifndef DONE_TYPEDEFS
  17 #define DONE_TYPEDEFS
  18 typedef struct config_tag Config;
  19 typedef struct backend_tag Backend;
  20 typedef struct terminal_tag Terminal;
  21 #endif
  22
  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;
  27
  28 #ifndef OSSOCKET_DEFINED
  29 typedef void *OSSocket;
  30 #endif
  31
  32 struct socket_function_table {
  33     Plug(*plug) (Socket s, Plug p);
  34     /* use a different plug (return the old one) */
  35     /* if p is NULL, it doesn't change the plug */
  36     /* but it does return the one it's using */
  37     void (*close) (Socket s);
  38     int (*write) (Socket s, const char *data, int len);
  39     int (*write_oob) (Socket s, const char *data, int len);
  40     void (*flush) (Socket s);
  41     void (*set_private_ptr) (Socket s, void *ptr);
  42     void *(*get_private_ptr) (Socket s);
  43     void (*set_frozen) (Socket s, int is_frozen);
  44     /* ignored by tcp, but vital for ssl */
  45     const char *(*socket_error) (Socket s);
  46 };
  47
  48 struct plug_function_table {
  49     void (*log)(Plug p, int type, SockAddr addr, int port,
  50                 const char *error_msg, int error_code);
  51     /*
  52      * Passes the client progress reports on the process of setting
  53      * up the connection.
  54      *
  55      *  - type==0 means we are about to try to connect to address
  56      *    `addr' (error_msg and error_code are ignored)
  57      *  - type==1 means we have failed to connect to address `addr'
  58      *    (error_msg and error_code are supplied). This is not a
  59      *    fatal error - we may well have other candidate addresses
  60      *    to fall back to. When it _is_ fatal, the closing()
  61      *    function will be called.
  62      */
  63     int (*closing)
  64      (Plug p, const char *error_msg, int error_code, int calling_back);
  65     /* error_msg is NULL iff it is not an error (ie it closed normally) */
  66     /* calling_back != 0 iff there is a Plug function */
  67     /* currently running (would cure the fixme in try_send()) */
  68     int (*receive) (Plug p, int urgent, char *data, int len);
  69     /*
  70      *  - urgent==0. `data' points to `len' bytes of perfectly
  71      *    ordinary data.
  72      *
  73      *  - urgent==1. `data' points to `len' bytes of data,
  74      *    which were read from before an Urgent pointer.
  75      *
  76      *  - urgent==2. `data' points to `len' bytes of data,
  77      *    the first of which was the one at the Urgent mark.
  78      */
  79     void (*sent) (Plug p, int bufsize);
  80     /*
  81      * The `sent' function is called when the pending send backlog
  82      * on a socket is cleared or partially cleared. The new backlog
  83      * size is passed in the `bufsize' parameter.
  84      */
  85     int (*accepting)(Plug p, OSSocket sock);
  86     /*
  87      * returns 0 if the host at address addr is a valid host for connecting or error
  88      */
  89 };
  90
  91 /* proxy indirection layer */
  92 /* NB, control of 'addr' is passed via new_connection, which takes
  93  * responsibility for freeing it */
  94 Socket new_connection(SockAddr addr, char *hostname,
  95                       int port, int privport,
  96                       int oobinline, int nodelay, int keepalive,
  97                       Plug plug, const Config *cfg);
  98 Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,
  99                     const Config *cfg, int addressfamily);
 100 SockAddr name_lookup(char *host, int port, char **canonicalname,
 101                      const Config *cfg, int addressfamily);
 102
 103 /* platform-dependent callback from new_connection() */
 104 /* (same caveat about addr as new_connection()) */
 105 Socket platform_new_connection(SockAddr addr, char *hostname,
 106                                int port, int privport,
 107                                int oobinline, int nodelay, int keepalive,
 108                                Plug plug, const Config *cfg);
 109
 110 /* socket functions */
 111
 112 void sk_init(void);                    /* called once at program startup */
 113 void sk_cleanup(void);                 /* called just before program exit */
 114
 115 SockAddr sk_namelookup(const char *host, char **canonicalname, int address_family);
 116 SockAddr sk_nonamelookup(const char *host);
 117 void sk_getaddr(SockAddr addr, char *buf, int buflen);
 118 int sk_hostname_is_local(char *name);
 119 int sk_address_is_local(SockAddr addr);
 120 int sk_addrtype(SockAddr addr);
 121 void sk_addrcopy(SockAddr addr, char *buf);
 122 void sk_addr_free(SockAddr addr);
 123 /* sk_addr_dup generates another SockAddr which contains the same data
 124  * as the original one and can be freed independently. May not actually
 125  * physically _duplicate_ it: incrementing a reference count so that
 126  * one more free is required before it disappears is an acceptable
 127  * implementation. */
 128 SockAddr sk_addr_dup(SockAddr addr);
 129
 130 /* NB, control of 'addr' is passed via sk_new, which takes responsibility
 131  * for freeing it, as for new_connection() */
 132 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
 133               int nodelay, int keepalive, Plug p);
 134
 135 Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only, int address_family);
 136
 137 Socket sk_register(OSSocket sock, Plug plug);
 138
 139 #define sk_plug(s,p) (((*s)->plug) (s, p))
 140 #define sk_close(s) (((*s)->close) (s))
 141 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
 142 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
 143 #define sk_flush(s) (((*s)->flush) (s))
 144
 145 #ifdef DEFINE_PLUG_METHOD_MACROS
 146 #define plug_log(p,type,addr,port,msg,code) (((*p)->log) (p, type, addr, port, msg, code))
 147 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
 148 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
 149 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
 150 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock))
 151 #endif
 152
 153 /*
 154  * Each socket abstraction contains a `void *' private field in
 155  * which the client can keep state.
 156  *
 157  * This is perhaps unnecessary now that we have the notion of a plug,
 158  * but there is some existing code that uses it, so it stays.
 159  */
 160 #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr))
 161 #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s))
 162
 163 /*
 164  * Special error values are returned from sk_namelookup and sk_new
 165  * if there's a problem. These functions extract an error message,
 166  * or return NULL if there's no problem.
 167  */
 168 const char *sk_addr_error(SockAddr addr);
 169 #define sk_socket_error(s) (((*s)->socket_error) (s))
 170
 171 /*
 172  * Set the `frozen' flag on a socket. A frozen socket is one in
 173  * which all READABLE notifications are ignored, so that data is
 174  * not accepted from the peer until the socket is unfrozen. This
 175  * exists for two purposes:
 176  *
 177  *  - Port forwarding: when a local listening port receives a
 178  *    connection, we do not want to receive data from the new
 179  *    socket until we have somewhere to send it. Hence, we freeze
 180  *    the socket until its associated SSH channel is ready; then we
 181  *    unfreeze it and pending data is delivered.
 182  *
 183  *  - Socket buffering: if an SSH channel (or the whole connection)
 184  *    backs up or presents a zero window, we must freeze the
 185  *    associated local socket in order to avoid unbounded buffer
 186  *    growth.
 187  */
 188 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))
 189
 190 /*
 191  * Call this after an operation that might have tried to send on a
 192  * socket, to clean up any pending network errors.
 193  */
 194 void net_pending_errors(void);
 195
 196 /*
 197  * Simple wrapper on getservbyname(), needed by ssh.c. Returns the
 198  * port number, in host byte order (suitable for printf and so on).
 199  * Returns 0 on failure. Any platform not supporting getservbyname
 200  * can just return 0 - this function is not required to handle
 201  * numeric port specifications.
 202  */
 203 int net_service_lookup(char *service);
 204
 205 /*
 206  * Look up the local hostname; return value needs freeing.
 207  * May return NULL.
 208  */
 209 char *get_hostname(void);
 210
 211 /********** SSL stuff **********/
 212
 213 /*
 214  * This section is subject to change, but you get the general idea
 215  * of what it will eventually look like.
 216  */
 217
 218 typedef struct certificate *Certificate;
 219 typedef struct our_certificate *Our_Certificate;
 220     /* to be defined somewhere else, somehow */
 221
 222 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
 223 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
 224
 225 struct ssl_client_socket_function_table {
 226     struct socket_function_table base;
 227     void (*renegotiate) (SSL_Client_Socket s);
 228     /* renegotiate the cipher spec */
 229 };
 230
 231 struct ssl_client_plug_function_table {
 232     struct plug_function_table base;
 233     int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
 234     /* do we accept this certificate chain?  If not, why not? */
 235     /* cert[0] is the server's certificate, cert[] is NULL-terminated */
 236     /* the last certificate may or may not be the root certificate */
 237      Our_Certificate(*client_cert) (SSL_Client_Plug p);
 238     /* the server wants us to identify ourselves */
 239     /* may return NULL if we want anonymity */
 240 };
 241
 242 SSL_Client_Socket sk_ssl_client_over(Socket s,  /* pre-existing (tcp) connection */
 243                                      SSL_Client_Plug p);
 244
 245 #define sk_renegotiate(s) (((*s)->renegotiate) (s))
 246
 247 #endif