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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 | void (*set_private_ptr) (Socket s, void *ptr); |
31 | void *(*get_private_ptr) (Socket s); |
32 | void (*set_frozen) (Socket s, int is_frozen); |
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33 | /* ignored by tcp, but vital for ssl */ |
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34 | char *(*socket_error) (Socket s); |
35 | }; |
36 | |
37 | struct plug_function_table { |
38 | int (*closing) |
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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()) */ |
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43 | int (*receive) (Plug p, int urgent, char *data, int len); |
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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 | */ |
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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 | */ |
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60 | int (*accepting)(Plug p, void *sock); |
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61 | /* |
62 | * returns 0 if the host at address addr is a valid host for connecting or error |
63 | */ |
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64 | }; |
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65 | |
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66 | /* proxy indirection layer */ |
67 | Socket new_connection(SockAddr addr, char *hostname, |
68 | int port, int privport, |
69 | int oobinline, int nodelay, Plug plug); |
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70 | Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only); |
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71 | SockAddr name_lookup(char *host, int port, char **canonicalname); |
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72 | |
73 | /* socket functions */ |
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74 | |
75 | void sk_init(void); /* called once at program startup */ |
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76 | void sk_cleanup(void); /* called just before program exit */ |
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77 | |
78 | SockAddr sk_namelookup(char *host, char **canonicalname); |
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79 | SockAddr sk_nonamelookup(char *host); |
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80 | void sk_getaddr(SockAddr addr, char *buf, int buflen); |
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81 | int sk_hostname_is_local(char *name); |
82 | int sk_address_is_local(SockAddr addr); |
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83 | enum { ADDRTYPE_IPV4, ADDRTYPE_IPV6, ADDRTYPE_NAME }; |
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84 | int sk_addrtype(SockAddr addr); |
85 | void sk_addrcopy(SockAddr addr, char *buf); |
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86 | void sk_addr_free(SockAddr addr); |
87 | |
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88 | Socket sk_new(SockAddr addr, int port, int privport, int oobinline, |
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89 | int nodelay, Plug p); |
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90 | |
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91 | Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only); |
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92 | |
93 | Socket sk_register(void *sock, Plug plug); |
94 | |
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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)) |
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104 | #define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize)) |
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105 | #define plug_accepting(p, sock) (((*p)->accepting)(p, sock)) |
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106 | #endif |
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107 | |
108 | /* |
109 | * Each socket abstraction contains a `void *' private field in |
110 | * which the client can keep state. |
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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. |
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114 | */ |
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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)) |
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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); |
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124 | #define sk_socket_error(s) (((*s)->socket_error) (s)) |
125 | |
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126 | /* |
127 | * Set the `frozen' flag on a socket. A frozen socket is one in |
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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. |
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142 | */ |
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143 | #define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen)) |
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144 | |
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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 | |
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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 | |
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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 | |
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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); |
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177 | /* renegotiate the cipher spec */ |
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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[]); |
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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 */ |
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189 | }; |
190 | |
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191 | SSL_Client_Socket sk_ssl_client_over(Socket s, /* pre-existing (tcp) connection */ |
192 | SSL_Client_Plug p); |
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193 | |
194 | #define sk_renegotiate(s) (((*s)->renegotiate) (s)) |
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195 | |
196 | #endif |