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); 123 124 /* NB, control of 'addr' is passed via sk_new, which takes responsibility 125 * for freeing it, as for new_connection() */ 126 Socket sk_new(SockAddr addr, int port, int privport, int oobinline, 127 int nodelay, int keepalive, Plug p); 128 129 Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only, int address_family); 130 131 Socket sk_register(OSSocket sock, Plug plug); 132 133 #define sk_plug(s,p) (((*s)->plug) (s, p)) 134 #define sk_close(s) (((*s)->close) (s)) 135 #define sk_write(s,buf,len) (((*s)->write) (s, buf, len)) 136 #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len)) 137 #define sk_flush(s) (((*s)->flush) (s)) 138 139 #ifdef DEFINE_PLUG_METHOD_MACROS 140 #define plug_log(p,type,addr,port,msg,code) (((*p)->log) (p, type, addr, port, msg, code)) 141 #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback)) 142 #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len)) 143 #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize)) 144 #define plug_accepting(p, sock) (((*p)->accepting)(p, sock)) 145 #endif 146 147 /* 148 * Each socket abstraction contains a `void *' private field in 149 * which the client can keep state. 150 * 151 * This is perhaps unnecessary now that we have the notion of a plug, 152 * but there is some existing code that uses it, so it stays. 153 */ 154 #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr)) 155 #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s)) 156 157 /* 158 * Special error values are returned from sk_namelookup and sk_new 159 * if there's a problem. These functions extract an error message, 160 * or return NULL if there's no problem. 161 */ 162 const char *sk_addr_error(SockAddr addr); 163 #define sk_socket_error(s) (((*s)->socket_error) (s)) 164 165 /* 166 * Set the `frozen' flag on a socket. A frozen socket is one in 167 * which all READABLE notifications are ignored, so that data is 168 * not accepted from the peer until the socket is unfrozen. This 169 * exists for two purposes: 170 * 171 * - Port forwarding: when a local listening port receives a 172 * connection, we do not want to receive data from the new 173 * socket until we have somewhere to send it. Hence, we freeze 174 * the socket until its associated SSH channel is ready; then we 175 * unfreeze it and pending data is delivered. 176 * 177 * - Socket buffering: if an SSH channel (or the whole connection) 178 * backs up or presents a zero window, we must freeze the 179 * associated local socket in order to avoid unbounded buffer 180 * growth. 181 */ 182 #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen)) 183 184 /* 185 * Call this after an operation that might have tried to send on a 186 * socket, to clean up any pending network errors. 187 */ 188 void net_pending_errors(void); 189 190 /* 191 * Simple wrapper on getservbyname(), needed by ssh.c. Returns the 192 * port number, in host byte order (suitable for printf and so on). 193 * Returns 0 on failure. Any platform not supporting getservbyname 194 * can just return 0 - this function is not required to handle 195 * numeric port specifications. 196 */ 197 int net_service_lookup(char *service); 198 199 /********** SSL stuff **********/ 200 201 /* 202 * This section is subject to change, but you get the general idea 203 * of what it will eventually look like. 204 */ 205 206 typedef struct certificate *Certificate; 207 typedef struct our_certificate *Our_Certificate; 208 /* to be defined somewhere else, somehow */ 209 210 typedef struct ssl_client_socket_function_table **SSL_Client_Socket; 211 typedef struct ssl_client_plug_function_table **SSL_Client_Plug; 212 213 struct ssl_client_socket_function_table { 214 struct socket_function_table base; 215 void (*renegotiate) (SSL_Client_Socket s); 216 /* renegotiate the cipher spec */ 217 }; 218 219 struct ssl_client_plug_function_table { 220 struct plug_function_table base; 221 int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]); 222 /* do we accept this certificate chain? If not, why not? */ 223 /* cert[0] is the server's certificate, cert[] is NULL-terminated */ 224 /* the last certificate may or may not be the root certificate */ 225 Our_Certificate(*client_cert) (SSL_Client_Plug p); 226 /* the server wants us to identify ourselves */ 227 /* may return NULL if we want anonymity */ 228 }; 229 230 SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */ 231 SSL_Client_Plug p); 232 233 #define sk_renegotiate(s) (((*s)->renegotiate) (s)) 234 235 #endif 236