зеркало из https://github.com/github/putty.git
566 строки
14 KiB
C
566 строки
14 KiB
C
/*
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* SSH port forwarding.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "putty.h"
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#include "ssh.h"
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#ifndef FALSE
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#define FALSE 0
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#endif
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#ifndef TRUE
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#define TRUE 1
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#endif
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struct PFwdPrivate {
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const struct plug_function_table *fn;
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/* the above variable absolutely *must* be the first in this structure */
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void *c; /* (channel) data used by ssh.c */
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void *backhandle; /* instance of SSH backend itself */
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/* Note that backhandle need not be filled in if c is non-NULL */
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Socket s;
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int throttled, throttle_override;
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int ready;
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/*
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* `dynamic' does double duty. It's set to 0 for an ordinary
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* forwarded port, and nonzero for SOCKS-style dynamic port
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* forwarding; but it also represents the state of the SOCKS
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* exchange.
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*/
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int dynamic;
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/*
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* `hostname' and `port' are the real hostname and port, once
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* we know what we're connecting to; they're unused for this
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* purpose while conducting a local SOCKS exchange, which means
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* we can also use them as a buffer and pointer for reading
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* data from the SOCKS client.
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*/
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char hostname[256+8];
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int port;
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/*
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* When doing dynamic port forwarding, we can receive
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* connection data before we are actually able to send it; so
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* we may have to temporarily hold some in a dynamically
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* allocated buffer here.
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*/
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void *buffer;
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int buflen;
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};
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static void pfd_log(Plug plug, int type, SockAddr addr, int port,
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const char *error_msg, int error_code)
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{
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/* we have to dump these since we have no interface to logging.c */
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}
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static int pfd_closing(Plug plug, const char *error_msg, int error_code,
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int calling_back)
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{
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struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
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/*
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* We have no way to communicate down the forwarded connection,
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* so if an error occurred on the socket, we just ignore it
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* and treat it like a proper close.
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*
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* FIXME: except we could initiate a full close here instead of
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* just an outgoing EOF? ssh.c currently has no API for that, but
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* it could.
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*/
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if (pr->c)
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sshfwd_write_eof(pr->c);
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return 1;
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}
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static int pfd_receive(Plug plug, int urgent, char *data, int len)
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{
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struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
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if (pr->dynamic) {
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while (len--) {
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/*
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* Throughout SOCKS negotiation, "hostname" is re-used as a
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* random protocol buffer with "port" storing the length.
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*/
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if (pr->port >= lenof(pr->hostname)) {
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/* Request too long. */
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if ((pr->dynamic >> 12) == 4) {
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/* Send back a SOCKS 4 error before closing. */
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char data[8];
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memset(data, 0, sizeof(data));
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data[1] = 91; /* generic `request rejected' */
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sk_write(pr->s, data, 8);
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}
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pfd_close(pr->s);
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return 1;
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}
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pr->hostname[pr->port++] = *data++;
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/*
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* Now check what's in the buffer to see if it's a
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* valid and complete message in the SOCKS exchange.
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*/
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if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
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pr->hostname[0] == 4) {
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/*
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* SOCKS 4.
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*/
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if (pr->dynamic == 1)
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pr->dynamic = 0x4000;
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if (pr->port < 2) continue;/* don't have command code yet */
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if (pr->hostname[1] != 1) {
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/* Not CONNECT. */
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/* Send back a SOCKS 4 error before closing. */
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char data[8];
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memset(data, 0, sizeof(data));
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data[1] = 91; /* generic `request rejected' */
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sk_write(pr->s, data, 8);
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pfd_close(pr->s);
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return 1;
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}
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if (pr->port <= 8) continue; /* haven't started user/hostname */
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if (pr->hostname[pr->port-1] != 0)
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continue; /* haven't _finished_ user/hostname */
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/*
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* Now we have a full SOCKS 4 request. Check it to
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* see if it's a SOCKS 4A request.
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*/
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if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
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pr->hostname[6] == 0 && pr->hostname[7] != 0) {
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/*
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* It's SOCKS 4A. So if we haven't yet
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* collected the host name, we should continue
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* waiting for data in order to do so; if we
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* have, we can go ahead.
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*/
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int len;
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if (pr->dynamic == 0x4000) {
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pr->dynamic = 0x4001;
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pr->port = 8; /* reset buffer to overwrite name */
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continue;
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}
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pr->hostname[0] = 0; /* reply version code */
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pr->hostname[1] = 90; /* request granted */
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sk_write(pr->s, pr->hostname, 8);
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len= pr->port - 8;
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pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
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memmove(pr->hostname, pr->hostname + 8, len);
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goto connect;
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} else {
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/*
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* It's SOCKS 4, which means we should format
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* the IP address into the hostname string and
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* then just go.
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*/
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pr->hostname[0] = 0; /* reply version code */
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pr->hostname[1] = 90; /* request granted */
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sk_write(pr->s, pr->hostname, 8);
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pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
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sprintf(pr->hostname, "%d.%d.%d.%d",
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(unsigned char)pr->hostname[4],
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(unsigned char)pr->hostname[5],
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(unsigned char)pr->hostname[6],
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(unsigned char)pr->hostname[7]);
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goto connect;
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}
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}
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if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
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pr->hostname[0] == 5) {
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/*
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* SOCKS 5.
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*/
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if (pr->dynamic == 1)
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pr->dynamic = 0x5000;
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if (pr->dynamic == 0x5000) {
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int i, method;
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char data[2];
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/*
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* We're receiving a set of method identifiers.
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*/
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if (pr->port < 2) continue;/* no method count yet */
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if (pr->port < 2 + (unsigned char)pr->hostname[1])
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continue; /* no methods yet */
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method = 0xFF; /* invalid */
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for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
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if (pr->hostname[2+i] == 0) {
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method = 0;/* no auth */
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break;
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}
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data[0] = 5;
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data[1] = method;
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sk_write(pr->s, data, 2);
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pr->dynamic = 0x5001;
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pr->port = 0; /* re-empty the buffer */
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continue;
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}
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if (pr->dynamic == 0x5001) {
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/*
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* We're receiving a SOCKS request.
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*/
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unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
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int atype, alen = 0;
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/*
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* Pre-fill reply packet.
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* In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
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* (atyp=1) in the reply; if we succeed, we don't know
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* the right answers, and if we fail, they should be
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* ignored.
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*/
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memset(reply, 0, lenof(reply));
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reply[0] = 5; /* VER */
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reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
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if (pr->port < 6) continue;
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atype = (unsigned char)pr->hostname[3];
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if (atype == 1) /* IPv4 address */
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alen = 4;
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if (atype == 4) /* IPv6 address */
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alen = 16;
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if (atype == 3) /* domain name has leading length */
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alen = 1 + (unsigned char)pr->hostname[4];
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if (pr->port < 6 + alen) continue;
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if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
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/* Not CONNECT or reserved field nonzero - error */
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reply[1] = 1; /* generic failure */
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sk_write(pr->s, (char *) reply, lenof(reply));
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pfd_close(pr->s);
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return 1;
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}
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/*
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* Now we have a viable connect request. Switch
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* on atype.
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*/
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pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
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if (atype == 1) {
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/* REP=0 (success) already */
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sk_write(pr->s, (char *) reply, lenof(reply));
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sprintf(pr->hostname, "%d.%d.%d.%d",
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(unsigned char)pr->hostname[4],
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(unsigned char)pr->hostname[5],
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(unsigned char)pr->hostname[6],
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(unsigned char)pr->hostname[7]);
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goto connect;
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} else if (atype == 3) {
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/* REP=0 (success) already */
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sk_write(pr->s, (char *) reply, lenof(reply));
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memmove(pr->hostname, pr->hostname + 5, alen-1);
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pr->hostname[alen-1] = '\0';
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goto connect;
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} else {
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/*
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* Unknown address type. (FIXME: support IPv6!)
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*/
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reply[1] = 8; /* atype not supported */
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sk_write(pr->s, (char *) reply, lenof(reply));
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pfd_close(pr->s);
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return 1;
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}
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}
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}
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/*
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* If we get here without either having done `continue'
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* or `goto connect', it must be because there is no
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* sensible interpretation of what's in our buffer. So
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* close the connection rudely.
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*/
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pfd_close(pr->s);
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return 1;
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}
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return 1;
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/*
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* We come here when we're ready to make an actual
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* connection.
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*/
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connect:
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/*
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* Freeze the socket until the SSH server confirms the
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* connection.
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*/
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sk_set_frozen(pr->s, 1);
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pr->c = new_sock_channel(pr->backhandle, pr->s);
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if (pr->c == NULL) {
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pfd_close(pr->s);
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return 1;
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} else {
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/* asks to forward to the specified host/port for this */
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ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
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}
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pr->dynamic = 0;
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/*
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* If there's any data remaining in our current buffer,
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* save it to be sent on pfd_confirm().
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*/
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if (len > 0) {
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pr->buffer = snewn(len, char);
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memcpy(pr->buffer, data, len);
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pr->buflen = len;
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}
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}
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if (pr->ready) {
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if (sshfwd_write(pr->c, data, len) > 0) {
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pr->throttled = 1;
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sk_set_frozen(pr->s, 1);
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}
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}
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return 1;
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}
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static void pfd_sent(Plug plug, int bufsize)
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{
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struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
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if (pr->c)
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sshfwd_unthrottle(pr->c, bufsize);
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}
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/*
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* Called when receiving a PORT OPEN from the server
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*/
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const char *pfd_newconnect(Socket *s, char *hostname, int port,
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void *c, Conf *conf, int addressfamily)
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{
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static const struct plug_function_table fn_table = {
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pfd_log,
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pfd_closing,
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pfd_receive,
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pfd_sent,
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NULL
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};
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SockAddr addr;
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const char *err;
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char *dummy_realhost;
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struct PFwdPrivate *pr;
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/*
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* Try to find host.
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*/
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addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
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if ((err = sk_addr_error(addr)) != NULL) {
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sk_addr_free(addr);
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return err;
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}
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/*
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* Open socket.
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*/
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pr = snew(struct PFwdPrivate);
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pr->buffer = NULL;
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pr->fn = &fn_table;
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pr->throttled = pr->throttle_override = 0;
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pr->ready = 1;
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pr->c = c;
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pr->backhandle = NULL; /* we shouldn't need this */
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pr->dynamic = 0;
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pr->s = *s = new_connection(addr, dummy_realhost, port,
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0, 1, 0, 0, (Plug) pr, conf);
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if ((err = sk_socket_error(*s)) != NULL) {
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sfree(pr);
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return err;
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}
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sk_set_private_ptr(*s, pr);
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return NULL;
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}
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/*
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called when someone connects to the local port
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*/
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static int pfd_accepting(Plug p, OSSocket sock)
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{
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static const struct plug_function_table fn_table = {
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pfd_log,
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pfd_closing,
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pfd_receive,
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pfd_sent,
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NULL
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};
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struct PFwdPrivate *pr, *org;
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Socket s;
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const char *err;
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org = (struct PFwdPrivate *)p;
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pr = snew(struct PFwdPrivate);
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pr->buffer = NULL;
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pr->fn = &fn_table;
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pr->c = NULL;
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pr->backhandle = org->backhandle;
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pr->s = s = sk_register(sock, (Plug) pr);
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if ((err = sk_socket_error(s)) != NULL) {
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sfree(pr);
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return err != NULL;
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}
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sk_set_private_ptr(s, pr);
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pr->throttled = pr->throttle_override = 0;
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pr->ready = 0;
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if (org->dynamic) {
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pr->dynamic = 1;
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pr->port = 0; /* "hostname" buffer is so far empty */
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sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
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} else {
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pr->dynamic = 0;
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strcpy(pr->hostname, org->hostname);
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pr->port = org->port;
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pr->c = new_sock_channel(org->backhandle, s);
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if (pr->c == NULL) {
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sfree(pr);
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return 1;
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} else {
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/* asks to forward to the specified host/port for this */
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ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
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}
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}
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return 0;
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}
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/* Add a new forwarding from port -> desthost:destport
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sets up a listener on the local machine on (srcaddr:)port
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*/
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const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
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int port, void *backhandle, Conf *conf,
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void **sockdata, int address_family)
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{
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static const struct plug_function_table fn_table = {
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pfd_log,
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pfd_closing,
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pfd_receive, /* should not happen... */
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pfd_sent, /* also should not happen */
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pfd_accepting
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};
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const char *err;
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struct PFwdPrivate *pr;
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Socket s;
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/*
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* Open socket.
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*/
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pr = snew(struct PFwdPrivate);
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pr->buffer = NULL;
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pr->fn = &fn_table;
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pr->c = NULL;
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if (desthost) {
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strcpy(pr->hostname, desthost);
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pr->port = destport;
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pr->dynamic = 0;
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} else
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pr->dynamic = 1;
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pr->throttled = pr->throttle_override = 0;
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pr->ready = 0;
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pr->backhandle = backhandle;
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pr->s = s = new_listener(srcaddr, port, (Plug) pr,
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!conf_get_int(conf, CONF_lport_acceptall),
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conf, address_family);
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if ((err = sk_socket_error(s)) != NULL) {
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sfree(pr);
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return err;
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}
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sk_set_private_ptr(s, pr);
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*sockdata = (void *)s;
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return NULL;
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}
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void pfd_close(Socket s)
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{
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struct PFwdPrivate *pr;
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if (!s)
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return;
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pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
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sfree(pr->buffer);
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sfree(pr);
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sk_close(s);
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}
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/*
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* Terminate a listener.
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*/
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void pfd_terminate(void *sv)
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{
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pfd_close((Socket)sv);
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}
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void pfd_unthrottle(Socket s)
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{
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struct PFwdPrivate *pr;
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if (!s)
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return;
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pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
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pr->throttled = 0;
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sk_set_frozen(s, pr->throttled || pr->throttle_override);
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}
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void pfd_override_throttle(Socket s, int enable)
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{
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struct PFwdPrivate *pr;
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if (!s)
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return;
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pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
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pr->throttle_override = enable;
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sk_set_frozen(s, pr->throttled || pr->throttle_override);
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}
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/*
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* Called to send data down the raw connection.
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*/
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int pfd_send(Socket s, char *data, int len)
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{
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if (s == NULL)
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return 0;
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return sk_write(s, data, len);
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}
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|
|
void pfd_send_eof(Socket s)
|
|
{
|
|
sk_write_eof(s);
|
|
}
|
|
|
|
void pfd_confirm(Socket s)
|
|
{
|
|
struct PFwdPrivate *pr;
|
|
|
|
if (s == NULL)
|
|
return;
|
|
|
|
pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
|
|
pr->ready = 1;
|
|
sk_set_frozen(s, 0);
|
|
sk_write(s, NULL, 0);
|
|
if (pr->buffer) {
|
|
sshfwd_write(pr->c, pr->buffer, pr->buflen);
|
|
sfree(pr->buffer);
|
|
pr->buffer = NULL;
|
|
}
|
|
}
|