| 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 | int (*write) (Socket s, char *data, int len); |
| 28 | int (*write_oob) (Socket s, char *data, int len); |
| 29 | void (*flush) (Socket s); |
| 30 | void (*set_private_ptr) (Socket s, void *ptr); |
| 31 | void *(*get_private_ptr) (Socket s); |
| 32 | void (*set_frozen) (Socket s, int is_frozen); |
| 33 | /* ignored by tcp, but vital for ssl */ |
| 34 | char *(*socket_error) (Socket s); |
| 35 | }; |
| 36 | |
| 37 | struct plug_function_table { |
| 38 | int (*closing) |
| 39 | (Plug p, char *error_msg, int error_code, int calling_back); |
| 40 | /* error_msg is NULL iff it is not an error (ie it closed normally) */ |
| 41 | /* calling_back != 0 iff there is a Plug function */ |
| 42 | /* currently running (would cure the fixme in try_send()) */ |
| 43 | int (*receive) (Plug p, int urgent, char *data, int len); |
| 44 | /* |
| 45 | * - urgent==0. `data' points to `len' bytes of perfectly |
| 46 | * ordinary data. |
| 47 | * |
| 48 | * - urgent==1. `data' points to `len' bytes of data, |
| 49 | * which were read from before an Urgent pointer. |
| 50 | * |
| 51 | * - urgent==2. `data' points to `len' bytes of data, |
| 52 | * the first of which was the one at the Urgent mark. |
| 53 | */ |
| 54 | void (*sent) (Plug p, int bufsize); |
| 55 | /* |
| 56 | * The `sent' function is called when the pending send backlog |
| 57 | * on a socket is cleared or partially cleared. The new backlog |
| 58 | * size is passed in the `bufsize' parameter. |
| 59 | */ |
| 60 | int (*accepting)(Plug p, void *sock); |
| 61 | /* |
| 62 | * returns 0 if the host at address addr is a valid host for connecting or error |
| 63 | */ |
| 64 | }; |
| 65 | |
| 66 | /* proxy indirection layer */ |
| 67 | Socket new_connection(SockAddr addr, char *hostname, |
| 68 | int port, int privport, |
| 69 | int oobinline, int nodelay, Plug plug); |
| 70 | Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only); |
| 71 | SockAddr name_lookup(char *host, int port, char **canonicalname); |
| 72 | |
| 73 | /* socket functions */ |
| 74 | |
| 75 | void sk_init(void); /* called once at program startup */ |
| 76 | void sk_cleanup(void); /* called just before program exit */ |
| 77 | |
| 78 | SockAddr sk_namelookup(char *host, char **canonicalname); |
| 79 | SockAddr sk_nonamelookup(char *host); |
| 80 | void sk_getaddr(SockAddr addr, char *buf, int buflen); |
| 81 | int sk_hostname_is_local(char *name); |
| 82 | int sk_address_is_local(SockAddr addr); |
| 83 | enum { ADDRTYPE_IPV4, ADDRTYPE_IPV6, ADDRTYPE_NAME }; |
| 84 | int sk_addrtype(SockAddr addr); |
| 85 | void sk_addrcopy(SockAddr addr, char *buf); |
| 86 | void sk_addr_free(SockAddr addr); |
| 87 | |
| 88 | Socket sk_new(SockAddr addr, int port, int privport, int oobinline, |
| 89 | int nodelay, Plug p); |
| 90 | |
| 91 | Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only); |
| 92 | |
| 93 | Socket sk_register(void *sock, Plug plug); |
| 94 | |
| 95 | #define sk_plug(s,p) (((*s)->plug) (s, p)) |
| 96 | #define sk_close(s) (((*s)->close) (s)) |
| 97 | #define sk_write(s,buf,len) (((*s)->write) (s, buf, len)) |
| 98 | #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len)) |
| 99 | #define sk_flush(s) (((*s)->flush) (s)) |
| 100 | |
| 101 | #ifdef DEFINE_PLUG_METHOD_MACROS |
| 102 | #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback)) |
| 103 | #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len)) |
| 104 | #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize)) |
| 105 | #define plug_accepting(p, sock) (((*p)->accepting)(p, sock)) |
| 106 | #endif |
| 107 | |
| 108 | /* |
| 109 | * Each socket abstraction contains a `void *' private field in |
| 110 | * which the client can keep state. |
| 111 | * |
| 112 | * This is perhaps unnecessary now that we have the notion of a plug, |
| 113 | * but there is some existing code that uses it, so it stays. |
| 114 | */ |
| 115 | #define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr)) |
| 116 | #define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s)) |
| 117 | |
| 118 | /* |
| 119 | * Special error values are returned from sk_namelookup and sk_new |
| 120 | * if there's a problem. These functions extract an error message, |
| 121 | * or return NULL if there's no problem. |
| 122 | */ |
| 123 | char *sk_addr_error(SockAddr addr); |
| 124 | #define sk_socket_error(s) (((*s)->socket_error) (s)) |
| 125 | |
| 126 | /* |
| 127 | * Set the `frozen' flag on a socket. A frozen socket is one in |
| 128 | * which all READABLE notifications are ignored, so that data is |
| 129 | * not accepted from the peer until the socket is unfrozen. This |
| 130 | * exists for two purposes: |
| 131 | * |
| 132 | * - Port forwarding: when a local listening port receives a |
| 133 | * connection, we do not want to receive data from the new |
| 134 | * socket until we have somewhere to send it. Hence, we freeze |
| 135 | * the socket until its associated SSH channel is ready; then we |
| 136 | * unfreeze it and pending data is delivered. |
| 137 | * |
| 138 | * - Socket buffering: if an SSH channel (or the whole connection) |
| 139 | * backs up or presents a zero window, we must freeze the |
| 140 | * associated local socket in order to avoid unbounded buffer |
| 141 | * growth. |
| 142 | */ |
| 143 | #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen)) |
| 144 | |
| 145 | /* |
| 146 | * Call this after an operation that might have tried to send on a |
| 147 | * socket, to clean up any pending network errors. |
| 148 | */ |
| 149 | void net_pending_errors(void); |
| 150 | |
| 151 | /* |
| 152 | * Simple wrapper on getservbyname(), needed by ssh.c. Returns the |
| 153 | * port number, in host byte order (suitable for printf and so on). |
| 154 | * Returns 0 on failure. Any platform not supporting getservbyname |
| 155 | * can just return 0 - this function is not required to handle |
| 156 | * numeric port specifications. |
| 157 | */ |
| 158 | int net_service_lookup(char *service); |
| 159 | |
| 160 | /********** SSL stuff **********/ |
| 161 | |
| 162 | /* |
| 163 | * This section is subject to change, but you get the general idea |
| 164 | * of what it will eventually look like. |
| 165 | */ |
| 166 | |
| 167 | typedef struct certificate *Certificate; |
| 168 | typedef struct our_certificate *Our_Certificate; |
| 169 | /* to be defined somewhere else, somehow */ |
| 170 | |
| 171 | typedef struct ssl_client_socket_function_table **SSL_Client_Socket; |
| 172 | typedef struct ssl_client_plug_function_table **SSL_Client_Plug; |
| 173 | |
| 174 | struct ssl_client_socket_function_table { |
| 175 | struct socket_function_table base; |
| 176 | void (*renegotiate) (SSL_Client_Socket s); |
| 177 | /* renegotiate the cipher spec */ |
| 178 | }; |
| 179 | |
| 180 | struct ssl_client_plug_function_table { |
| 181 | struct plug_function_table base; |
| 182 | int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]); |
| 183 | /* do we accept this certificate chain? If not, why not? */ |
| 184 | /* cert[0] is the server's certificate, cert[] is NULL-terminated */ |
| 185 | /* the last certificate may or may not be the root certificate */ |
| 186 | Our_Certificate(*client_cert) (SSL_Client_Plug p); |
| 187 | /* the server wants us to identify ourselves */ |
| 188 | /* may return NULL if we want anonymity */ |
| 189 | }; |
| 190 | |
| 191 | SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */ |
| 192 | SSL_Client_Plug p); |
| 193 | |
| 194 | #define sk_renegotiate(s) (((*s)->renegotiate) (s)) |
| 195 | |
| 196 | #endif |