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