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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. |
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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. |
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11 | */ |
12 | |
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13 | #ifndef PUTTY_NETWORK_H |
14 | #define PUTTY_NETWORK_H |
15 | |
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16 | typedef struct SockAddr_tag *SockAddr; |
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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 { |
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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 */ |
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26 | void (*close) (Socket s); |
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27 | int (*write) (Socket s, char *data, int len); |
28 | int (*write_oob) (Socket s, char *data, int len); |
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29 | void (*flush) (Socket s); |
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30 | /* ignored by tcp, but vital for ssl */ |
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31 | char *(*socket_error) (Socket s); |
32 | }; |
33 | |
34 | struct plug_function_table { |
35 | int (*closing) |
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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()) */ |
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40 | int (*receive) (Plug p, int urgent, char *data, int len); |
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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 | */ |
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51 | void (*sent) (Plug p, int bufsize); |
52 | /* |
53 | * The `sent' function is called when the pending send backlog |
54 | * on a socket is cleared or partially cleared. The new backlog |
55 | * size is passed in the `bufsize' parameter. |
56 | */ |
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57 | int (*accepting)(Plug p, void *sock); |
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58 | /* |
59 | * returns 0 if the host at address addr is a valid host for connecting or error |
60 | */ |
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61 | }; |
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62 | |
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63 | |
64 | void sk_init(void); /* called once at program startup */ |
65 | |
66 | SockAddr sk_namelookup(char *host, char **canonicalname); |
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67 | void sk_getaddr(SockAddr addr, char *buf, int buflen); |
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68 | void sk_addr_free(SockAddr addr); |
69 | |
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70 | Socket sk_new(SockAddr addr, int port, int privport, int oobinline, |
71 | Plug p); |
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72 | |
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73 | Socket sk_newlistener(int port, Plug plug, int local_host_only); |
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74 | |
75 | Socket sk_register(void *sock, Plug plug); |
76 | |
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77 | #define sk_plug(s,p) (((*s)->plug) (s, p)) |
78 | #define sk_close(s) (((*s)->close) (s)) |
79 | #define sk_write(s,buf,len) (((*s)->write) (s, buf, len)) |
80 | #define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len)) |
81 | #define sk_flush(s) (((*s)->flush) (s)) |
82 | |
83 | #ifdef DEFINE_PLUG_METHOD_MACROS |
84 | #define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback)) |
85 | #define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len)) |
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86 | #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize)) |
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87 | #define plug_accepting(p, sock) (((*p)->accepting)(p, sock)) |
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88 | #endif |
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89 | |
90 | /* |
91 | * Each socket abstraction contains a `void *' private field in |
92 | * which the client can keep state. |
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93 | * |
94 | * This is perhaps unnecessary now that we have the notion of a plug, |
95 | * but there is some existing code that uses it, so it stays. |
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96 | */ |
97 | void sk_set_private_ptr(Socket s, void *ptr); |
98 | void *sk_get_private_ptr(Socket s); |
99 | |
100 | /* |
101 | * Special error values are returned from sk_namelookup and sk_new |
102 | * if there's a problem. These functions extract an error message, |
103 | * or return NULL if there's no problem. |
104 | */ |
105 | char *sk_addr_error(SockAddr addr); |
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106 | #define sk_socket_error(s) (((*s)->socket_error) (s)) |
107 | |
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108 | /* |
109 | * Set the `frozen' flag on a socket. A frozen socket is one in |
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110 | * which all READABLE notifications are ignored, so that data is |
111 | * not accepted from the peer until the socket is unfrozen. This |
112 | * exists for two purposes: |
113 | * |
114 | * - Port forwarding: when a local listening port receives a |
115 | * connection, we do not want to receive data from the new |
116 | * socket until we have somewhere to send it. Hence, we freeze |
117 | * the socket until its associated SSH channel is ready; then we |
118 | * unfreeze it and pending data is delivered. |
119 | * |
120 | * - Socket buffering: if an SSH channel (or the whole connection) |
121 | * backs up or presents a zero window, we must freeze the |
122 | * associated local socket in order to avoid unbounded buffer |
123 | * growth. |
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124 | */ |
125 | void sk_set_frozen(Socket sock, int is_frozen); |
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126 | |
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127 | /* |
128 | * Call this after an operation that might have tried to send on a |
129 | * socket, to clean up any pending network errors. |
130 | */ |
131 | void net_pending_errors(void); |
132 | |
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133 | /********** SSL stuff **********/ |
134 | |
135 | /* |
136 | * This section is subject to change, but you get the general idea |
137 | * of what it will eventually look like. |
138 | */ |
139 | |
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140 | typedef struct certificate *Certificate; |
141 | typedef struct our_certificate *Our_Certificate; |
142 | /* to be defined somewhere else, somehow */ |
143 | |
144 | typedef struct ssl_client_socket_function_table **SSL_Client_Socket; |
145 | typedef struct ssl_client_plug_function_table **SSL_Client_Plug; |
146 | |
147 | struct ssl_client_socket_function_table { |
148 | struct socket_function_table base; |
149 | void (*renegotiate) (SSL_Client_Socket s); |
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150 | /* renegotiate the cipher spec */ |
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151 | }; |
152 | |
153 | struct ssl_client_plug_function_table { |
154 | struct plug_function_table base; |
155 | int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]); |
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156 | /* do we accept this certificate chain? If not, why not? */ |
157 | /* cert[0] is the server's certificate, cert[] is NULL-terminated */ |
158 | /* the last certificate may or may not be the root certificate */ |
159 | Our_Certificate(*client_cert) (SSL_Client_Plug p); |
160 | /* the server wants us to identify ourselves */ |
161 | /* may return NULL if we want anonymity */ |
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162 | }; |
163 | |
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164 | SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */ |
165 | SSL_Client_Plug p); |
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166 | |
167 | #define sk_renegotiate(s) (((*s)->renegotiate) (s)) |
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168 | |
169 | #endif |