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 };
  52
  53
  54 void sk_init(void);                    /* called once at program startup */
  55
  56 SockAddr sk_namelookup(char *host, char **canonicalname);
  57 void sk_addr_free(SockAddr addr);
  58
  59 Socket sk_new(SockAddr addr, int port, int privport, int oobinline, Plug p);
  60
  61 #define sk_plug(s,p) (((*s)->plug) (s, p))
  62 #define sk_close(s) (((*s)->close) (s))
  63 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len))
  64 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))
  65 #define sk_flush(s) (((*s)->flush) (s))
  66
  67 #ifdef DEFINE_PLUG_METHOD_MACROS
  68 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))
  69 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))
  70 #endif
  71
  72 /*
  73  * Each socket abstraction contains a `void *' private field in
  74  * which the client can keep state.
  75  *
  76  * This is perhaps unnecessary now that we have the notion of a plug,
  77  * but there is some existing code that uses it, so it stays.
  78  */
  79 void sk_set_private_ptr(Socket s, void *ptr);
  80 void *sk_get_private_ptr(Socket s);
  81
  82 /*
  83  * Special error values are returned from sk_namelookup and sk_new
  84  * if there's a problem. These functions extract an error message,
  85  * or return NULL if there's no problem.
  86  */
  87 char *sk_addr_error(SockAddr addr);
  88 #define sk_socket_error(s) (((*s)->socket_error) (s))
  89
  90
  91 /********** SSL stuff **********/
  92
  93 /*
  94  * This section is subject to change, but you get the general idea
  95  * of what it will eventually look like.
  96  */
  97
  98
  99 typedef struct certificate *Certificate;
 100 typedef struct our_certificate *Our_Certificate;
 101     /* to be defined somewhere else, somehow */
 102
 103 typedef struct ssl_client_socket_function_table **SSL_Client_Socket;
 104 typedef struct ssl_client_plug_function_table **SSL_Client_Plug;
 105
 106 struct ssl_client_socket_function_table {
 107     struct socket_function_table base;
 108     void (*renegotiate) (SSL_Client_Socket s);
 109         /* renegotiate the cipher spec */
 110 };
 111
 112 struct ssl_client_plug_function_table {
 113     struct plug_function_table base;
 114     int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);
 115         /* do we accept this certificate chain?  If not, why not? */
 116         /* cert[0] is the server's certificate, cert[] is NULL-terminated */
 117         /* the last certificate may or may not be the root certificate */
 118     Our_Certificate (*client_cert) (SSL_Client_Plug p);
 119         /* the server wants us to identify ourselves */
 120         /* may return NULL if we want anonymity */
 121 };
 122
 123 SSL_Client_Socket sk_ssl_client_over (
 124     Socket s, /* pre-existing (tcp) connection */
 125     SSL_Client_Plug p
 126 );
 127
 128 #define sk_renegotiate(s) (((*s)->renegotiate) (s))
 129
 130 #endif