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Add X11 forwarding, mainly thanks to Andreas Schultz
[originally from svn r878]
This commit is contained in:
Simon Tatham
276
x11fwd.c
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276
x11fwd.c
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#include <windows.h>
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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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#define GET_32BIT_LSB_FIRST(cp) \
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(((unsigned long)(unsigned char)(cp)[0]) | \
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((unsigned long)(unsigned char)(cp)[1] << 8) | \
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((unsigned long)(unsigned char)(cp)[2] << 16) | \
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((unsigned long)(unsigned char)(cp)[3] << 24))
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#define PUT_32BIT_LSB_FIRST(cp, value) ( \
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(cp)[0] = (value), \
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(cp)[1] = (value) >> 8, \
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(cp)[2] = (value) >> 16, \
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(cp)[3] = (value) >> 24 )
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#define GET_16BIT_LSB_FIRST(cp) \
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(((unsigned long)(unsigned char)(cp)[0]) | \
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((unsigned long)(unsigned char)(cp)[1] << 8))
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#define PUT_16BIT_LSB_FIRST(cp, value) ( \
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(cp)[0] = (value), \
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(cp)[1] = (value) >> 8 )
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#define GET_32BIT_MSB_FIRST(cp) \
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(((unsigned long)(unsigned char)(cp)[0] << 24) | \
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((unsigned long)(unsigned char)(cp)[1] << 16) | \
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((unsigned long)(unsigned char)(cp)[2] << 8) | \
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((unsigned long)(unsigned char)(cp)[3]))
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#define PUT_32BIT_MSB_FIRST(cp, value) ( \
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(cp)[0] = (value) >> 24, \
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(cp)[1] = (value) >> 16, \
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(cp)[2] = (value) >> 8, \
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(cp)[3] = (value) )
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#define GET_16BIT_MSB_FIRST(cp) \
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(((unsigned long)(unsigned char)(cp)[0] << 8) | \
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((unsigned long)(unsigned char)(cp)[1]))
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#define PUT_16BIT_MSB_FIRST(cp, value) ( \
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(cp)[0] = (value) >> 8, \
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(cp)[1] = (value) )
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#define GET_16BIT(endian, cp) \
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(endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
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#define PUT_16BIT(endian, cp, val) \
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(endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
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extern void sshfwd_close(void *);
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extern void sshfwd_write(void *, char *, int);
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struct X11Private {
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unsigned char firstpkt[12]; /* first X data packet */
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char *auth_protocol;
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unsigned char *auth_data;
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int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
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int verified;
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void *c; /* data used by ssh.c */
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};
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void x11_close (Socket s);
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static unsigned char x11_authdata[64];
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static int x11_authdatalen;
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void x11_invent_auth(char *proto, int protomaxlen,
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char *data, int datamaxlen) {
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char ourdata[64];
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int i;
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/* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
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x11_authdatalen = 16;
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for (i = 0; i < 16; i++)
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x11_authdata[i] = random_byte();
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/* Now format for the recipient. */
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strncpy(proto, "MIT-MAGIC-COOKIE-1", protomaxlen);
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ourdata[0] = '\0';
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for (i = 0; i < x11_authdatalen; i++)
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sprintf(ourdata+strlen(ourdata), "%02x", x11_authdata[i]);
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strncpy(data, ourdata, datamaxlen);
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}
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static int x11_verify(char *proto, unsigned char *data, int dlen) {
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if (strcmp(proto, "MIT-MAGIC-COOKIE-1") != 0)
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return 0; /* wrong protocol attempted */
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if (dlen != x11_authdatalen)
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return 0; /* cookie was wrong length */
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if (memcmp(x11_authdata, data, dlen) != 0)
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return 0; /* cookie was wrong cookie! */
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return 1;
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}
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static int x11_receive (Socket s, int urgent, char *data, int len) {
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struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s);
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if (!len) {
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/* Connection has closed. */
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sshfwd_close(pr->c);
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x11_close(s);
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return 1;
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}
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sshfwd_write(pr->c, data, len);
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return 1;
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}
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/*
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* Called to set up the raw connection.
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*
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* Returns an error message, or NULL on success.
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* also, fills the SocketsStructure
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*
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* Also places the canonical host name into `realhost'.
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*/
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char *x11_init (Socket *s, char *display, void *c, char **realhost) {
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SockAddr addr;
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int port;
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char *err;
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char host[128];
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int n, displaynum;
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struct X11Private *pr;
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/*
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* Split up display name into host and display-number parts.
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*/
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n = strcspn(display, ":");
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if (display[n])
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displaynum = atoi(display+n+1);
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else
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displaynum = 0; /* sensible default */
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if (n > sizeof(host)-1)
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n = sizeof(host)-1;
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strncpy(host, display, n);
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host[n] = '\0';
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/*
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* Try to find host.
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*/
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addr = sk_namelookup(host, realhost);
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if ( (err = sk_addr_error(addr)) )
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return err;
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port = 6000 + displaynum;
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/*
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* Open socket.
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*/
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*s = sk_new(addr, port, 0, x11_receive);
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if ( (err = sk_socket_error(*s)) )
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return err;
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pr = (struct X11Private *)smalloc(sizeof(struct X11Private));
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pr->auth_protocol = NULL;
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pr->verified = 0;
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pr->data_read = 0;
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pr->c = c;
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sk_set_private_ptr(*s, pr);
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sk_addr_free(addr);
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return NULL;
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}
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void x11_close (Socket s) {
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struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s);
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if (pr->auth_protocol) {
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sfree(pr->auth_protocol);
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sfree(pr->auth_data);
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}
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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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* Called to send data down the raw connection.
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*/
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void x11_send (Socket s, char *data, int len) {
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struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s);
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if (s == NULL)
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return;
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/*
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* Read the first packet.
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*/
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while (len > 0 && pr->data_read < 12)
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pr->firstpkt[pr->data_read++] = (unsigned char)(len--, *data++);
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if (pr->data_read < 12)
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return;
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/*
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* If we have not allocated the auth_protocol and auth_data
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* strings, do so now.
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*/
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if (!pr->auth_protocol) {
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pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+6);
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pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt+8);
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pr->auth_psize = (pr->auth_plen + 3) &~ 3;
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pr->auth_dsize = (pr->auth_dlen + 3) &~ 3;
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/* Leave room for a terminating zero, to make our lives easier. */
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pr->auth_protocol = (char *)smalloc(pr->auth_psize+1);
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pr->auth_data = (char *)smalloc(pr->auth_dsize);
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}
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/*
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* Read the auth_protocol and auth_data strings.
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*/
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while (len > 0 && pr->data_read < 12 + pr->auth_psize)
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pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
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while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
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pr->auth_data[pr->data_read++ - 12 -
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pr->auth_psize] = (unsigned char)(len--, *data++);
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if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
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return;
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/*
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* If we haven't verified the authentication, do so now.
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*/
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if (!pr->verified) {
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int ret;
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pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
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ret = x11_verify(pr->auth_protocol, pr->auth_data, pr->auth_dlen);
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/*
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* If authentication failed, construct and send an error
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* packet, then terminate the connection.
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*/
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if (!ret) {
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char message[] = "Authentication failed at PuTTY X11 proxy";
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unsigned char reply[8 + sizeof(message) + 4];
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int msglen = sizeof(message)-1; /* skip zero byte */
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int msgsize = (msglen+3) &~ 3;
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reply[0] = 0; /* failure */
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reply[1] = msglen; /* length of reason string */
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memcpy(reply+2, pr->firstpkt+2, 4); /* major/minor proto vsn */
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PUT_16BIT(pr->firstpkt[0], reply+6, msglen >> 2); /* data len */
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memset(reply+8, 0, msgsize);
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memcpy(reply+8, message, msglen);
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sshfwd_write(pr->c, reply, 8+msgsize);
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sshfwd_close(pr->c);
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x11_close(s);
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return;
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}
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/*
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* Now we know we're going to accept the connection. Strip
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* the auth data. (TODO: if we ever work out how, we should
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* replace some real auth data in here.)
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*/
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PUT_16BIT(pr->firstpkt[0], pr->firstpkt+6, 0); /* auth proto */
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PUT_16BIT(pr->firstpkt[0], pr->firstpkt+8, 0); /* auth data */
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sk_write(s, pr->firstpkt, 12);
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pr->verified = 1;
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}
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/*
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* After initialisation, just copy data simply.
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*/
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sk_write(s, data, len);
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}
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