git.distorted.org.uk Git - u/mdw/putty/blob - 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     int (*closing)
  50      (Plug p, const char *error_msg, int error_code, int calling_back);
  51     /* error_msg is NULL iff it is not an error (ie it closed normally) */
  52     /* calling_back != 0 iff there is a Plug function */
  53     /* currently running (would cure the fixme in try_send()) */
  54     int (*receive) (Plug p, int urgent, char *data, int len);
  55     /*
  56      *  - urgent==0. `data' points to `len' bytes of perfectly
  57      *    ordinary data.
  58      *
  59      *  - urgent==1. `data' points to `len' bytes of data,
  60      *    which were read from before an Urgent pointer.
  61      *
  62      *  - urgent==2. `data' points to `len' bytes of data,
  63      *    the first of which was the one at the Urgent mark.
  64      */
  65     void (*sent) (Plug p, int bufsize);
  66     /*
  67      * The `sent' function is called when the pending send backlog
  68      * on a socket is cleared or partially cleared. The new backlog
  69      * size is passed in the `bufsize' parameter.
  70      */
  71     int (*accepting)(Plug p, OSSocket sock);
  72     /*
  73      * returns 0 if the host at address addr is a valid host for connecting or error
  74      */
  75 };
  76
  77 /* proxy indirection layer */
  78 /* NB, control of 'addr' is passed via new_connection, which takes
  79  * responsibility for freeing it */
  80 Socket new_connection(SockAddr addr, char *hostname,
  81                       int port, int privport,
  82                       int oobinline, int nodelay, Plug plug,
  83                       const Config *cfg);
  84 Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,
  85                     const Config *cfg);
  86 SockAddr name_lookup(char *host, int port, char **canonicalname,
  87                      const Config *cfg);
  88
  89 /* platform-dependent callback from new_connection() */
  90 /* (same caveat about addr as new_connection()) */
  91 Socket platform_new_connection(SockAddr addr, char *hostname,
  92                                int port, int privport,
  93                                int oobinline, int nodelay, Plug plug,
  94                                const Config *cfg);
  95
  96 /* socket functions */
  97
  98 void sk_init(void);                    /* called once at program startup */
  99 void sk_cleanup(void);                 /* called just before program exit */
 100
 101 SockAddr sk_namelookup(const char *host, char **canonicalname);
 102 SockAddr sk_nonamelookup(const char *host);
 103 void sk_getaddr(SockAddr addr, char *buf, int buflen);
 104 int sk_hostname_is_local(char *name);
 105 int sk_address_is_local(SockAddr addr);
 106 enum { ADDRTYPE_IPV4, ADDRTYPE_IPV6, ADDRTYPE_NAME };
 107 int sk_addrtype(SockAddr addr);
 108 void sk_addrcopy(SockAddr addr, char *buf);
 109 void sk_addr_free(SockAddr addr);
 110
 111 /* NB, control of 'addr' is passed via sk_new, which takes responsibility
 112  * for freeing it, as for new_connection() */
 113 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
 114               int nodelay, Plug p);
 115
 116 Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only);
 117
 118 Socket sk_register(OSSocket sock, Plug plug);
 119
 120 #define sk_plug(s,p) (((*s)->plug) (s, p))
 121 #define sk_close(s) (((*s)->close) (s))
 122 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
 123 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
 124 #define sk_flush(s) (((*s)->flush) (s))
 125
 126 #ifdef DEFINE_PLUG_METHOD_MACROS
 127 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
 128 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
 129 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))
 130 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock))
 131 #endif
 132
 133 /*
 134  * Each socket abstraction contains a `void *' private field in
 135  * which the client can keep state.
 136  *
 137  * This is perhaps unnecessary now that we have the notion of a plug,
 138  * but there is some existing code that uses it, so it stays.
 139  */
 140 #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr))
 141 #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s))
 142
 143 /*
 144  * Special error values are returned from sk_namelookup and sk_new
 145  * if there's a problem. These functions extract an error message,
 146  * or return NULL if there's no problem.
 147  */
 148 const char *sk_addr_error(SockAddr addr);
 149 #define sk_socket_error(s) (((*s)->socket_error) (s))
 150
 151 /*
 152  * Set the `frozen' flag on a socket. A frozen socket is one in
 153  * which all READABLE notifications are ignored, so that data is
 154  * not accepted from the peer until the socket is unfrozen. This
 155  * exists for two purposes:
 156  *
 157  *  - Port forwarding: when a local listening port receives a
 158  *    connection, we do not want to receive data from the new
 159  *    socket until we have somewhere to send it. Hence, we freeze
 160  *    the socket until its associated SSH channel is ready; then we
 161  *    unfreeze it and pending data is delivered.
 162  *
 163  *  - Socket buffering: if an SSH channel (or the whole connection)
 164  *    backs up or presents a zero window, we must freeze the
 165  *    associated local socket in order to avoid unbounded buffer
 166  *    growth.
 167  */
 168 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))
 169
 170 /*
 171  * Call this after an operation that might have tried to send on a
 172  * socket, to clean up any pending network errors.
 173  */
 174 void net_pending_errors(void);
 175
 176 /*
 177  * Simple wrapper on getservbyname(), needed by ssh.c. Returns the
 178  * port number, in host byte order (suitable for printf and so on).
 179  * Returns 0 on failure. Any platform not supporting getservbyname
 180  * can just return 0 - this function is not required to handle
 181  * numeric port specifications.
 182  */
 183 int net_service_lookup(char *service);
 184
 185 /********** SSL stuff **********/
 186
 187 /*
 188  * This section is subject to change, but you get the general idea
 189  * of what it will eventually look like.
 190  */
 191
 192 typedef struct certificate *Certificate;
 193 typedef struct our_certificate *Our_Certificate;
 194     /* to be defined somewhere else, somehow */
 195
 196 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
 197 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
 198
 199 struct ssl_client_socket_function_table {
 200     struct socket_function_table base;
 201     void (*renegotiate) (SSL_Client_Socket s);
 202     /* renegotiate the cipher spec */
 203 };
 204
 205 struct ssl_client_plug_function_table {
 206     struct plug_function_table base;
 207     int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
 208     /* do we accept this certificate chain?  If not, why not? */
 209     /* cert[0] is the server's certificate, cert[] is NULL-terminated */
 210     /* the last certificate may or may not be the root certificate */
 211      Our_Certificate(*client_cert) (SSL_Client_Plug p);
 212     /* the server wants us to identify ourselves */
 213     /* may return NULL if we want anonymity */
 214 };
 215
 216 SSL_Client_Socket sk_ssl_client_over(Socket s,  /* pre-existing (tcp) connection */
 217                                      SSL_Client_Plug p);
 218
 219 #define sk_renegotiate(s) (((*s)->renegotiate) (s))
 220
 221 #endif