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 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;
  20
  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     void (*write) (Socket s, char *data, int len);
  28     void (*write_oob) (Socket s, char *data, int len);
  29     void (*flush) (Socket s);
  30     /* ignored by tcp, but vital for ssl */
  31     char *(*socket_error) (Socket s);
  32 };
  33
  34 struct plug_function_table {
  35     int (*closing)
  36      (Plug p, char *error_msg, int error_code, int calling_back);
  37     /* error_msg is NULL iff it is not an error (ie it closed normally) */
  38     /* calling_back != 0 iff there is a Plug function */
  39     /* currently running (would cure the fixme in try_send()) */
  40     int (*receive) (Plug p, int urgent, char *data, int len);
  41     /*
  42      *  - urgent==0. `data' points to `len' bytes of perfectly
  43      *    ordinary data.
  44      *
  45      *  - urgent==1. `data' points to `len' bytes of data,
  46      *    which were read from before an Urgent pointer.
  47      *
  48      *  - urgent==2. `data' points to `len' bytes of data,
  49      *    the first of which was the one at the Urgent mark.
  50      */
  51     int (*accepting)(Plug p, struct sockaddr *addr, void *sock);
  52     /*
  53      * returns 0 if the host at address addr is a valid host for connecting or error
  54      */
  55 };
  56
  57
  58 void sk_init(void);                    /* called once at program startup */
  59
  60 SockAddr sk_namelookup(char *host, char **canonicalname);
  61 void sk_addr_free(SockAddr addr);
  62
  63 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
  64               Plug p);
  65
  66 Socket sk_newlistenner(int port, Plug plug);
  67
  68 Socket sk_register(void *sock, Plug plug);
  69
  70 #define sk_plug(s,p) (((*s)->plug) (s, p))
  71 #define sk_close(s) (((*s)->close) (s))
  72 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
  73 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
  74 #define sk_flush(s) (((*s)->flush) (s))
  75
  76 #ifdef DEFINE_PLUG_METHOD_MACROS
  77 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
  78 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
  79 #define plug_accepting(p, addr, sock) (((*p)->accepting)(p, addr, sock))
  80 #endif
  81
  82 /*
  83  * Each socket abstraction contains a `void *' private field in
  84  * which the client can keep state.
  85  *
  86  * This is perhaps unnecessary now that we have the notion of a plug,
  87  * but there is some existing code that uses it, so it stays.
  88  */
  89 void sk_set_private_ptr(Socket s, void *ptr);
  90 void *sk_get_private_ptr(Socket s);
  91
  92 /*
  93  * Special error values are returned from sk_namelookup and sk_new
  94  * if there's a problem. These functions extract an error message,
  95  * or return NULL if there's no problem.
  96  */
  97 char *sk_addr_error(SockAddr addr);
  98 #define sk_socket_error(s) (((*s)->socket_error) (s))
  99
 100 /*
 101  * Set the `frozen' flag on a socket. A frozen socket is one in
 102  * which all sends are buffered and receives are ignored. This is
 103  * so that (for example) a new port-forwarding can sit in limbo
 104  * until its associated SSH channel is ready, and then pending data
 105  * can be sent on.
 106  */
 107 void sk_set_frozen(Socket sock, int is_frozen);
 108
 109 /********** SSL stuff **********/
 110
 111 /*
 112  * This section is subject to change, but you get the general idea
 113  * of what it will eventually look like.
 114  */
 115
 116 typedef struct certificate *Certificate;
 117 typedef struct our_certificate *Our_Certificate;
 118     /* to be defined somewhere else, somehow */
 119
 120 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
 121 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
 122
 123 struct ssl_client_socket_function_table {
 124     struct socket_function_table base;
 125     void (*renegotiate) (SSL_Client_Socket s);
 126     /* renegotiate the cipher spec */
 127 };
 128
 129 struct ssl_client_plug_function_table {
 130     struct plug_function_table base;
 131     int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
 132     /* do we accept this certificate chain?  If not, why not? */
 133     /* cert[0] is the server's certificate, cert[] is NULL-terminated */
 134     /* the last certificate may or may not be the root certificate */
 135      Our_Certificate(*client_cert) (SSL_Client_Plug p);
 136     /* the server wants us to identify ourselves */
 137     /* may return NULL if we want anonymity */
 138 };
 139
 140 SSL_Client_Socket sk_ssl_client_over(Socket s,  /* pre-existing (tcp) connection */
 141                                      SSL_Client_Plug p);
 142
 143 #define sk_renegotiate(s) (((*s)->renegotiate) (s))
 144
 145 #endif