#include <krb5/krb5.h>
#include <X11/Xlibint.h>
#include <X11/Xos.h>
#include <X11/k5encode.h>
#include <com_err.h>
#include <stdio.h>
#include "Xlibnet.h"
#include "k5cli.h"

extern krb5_flags krb5_kdc_default_options;

/*
 * k5_clientauth
 *
 * This hack gets inserted in the middle of the XOpenDisplay
 * code.  Returns non-zero if the setup prefix has been read,
 * so we can tell XOpenDisplay to not bother looking for it by
 * itself.
 */
int k5_clientauth(dpy, sprefix)
    Display *dpy;
    xConnSetupPrefix *sprefix;
{
    krb5_error_code retval;
    xReq prefix;
    char *buf;
    CARD16 plen, tlen;
    krb5_data kbuf;
    krb5_ccache cc;
    krb5_creds creds;
    krb5_principal cprinc, sprinc;
    krb5_ap_rep_enc_part *repl;

    krb5_init_ets();
    /*
     * stage 0: get encoded principal and tgt from server
     */
    _XRead(dpy, (char *)&prefix, sz_xReq);
    if (prefix.reqType != 2 && prefix.reqType != 3)
	/* not an auth packet... so deal */
	if (prefix.reqType == 0 || prefix.reqType == 1)
	{
	    bcopy((char *)&prefix, (char *)sprefix, sz_xReq);
	    _XRead(dpy, (char *)sprefix + sz_xReq,
		   sz_xConnSetupPrefix - sz_xReq); /* ewww... gross */
	    return 1;
	}
	else
	{
	    fprintf(stderr, "Xlib: server is royally confused\n");
	    return -1;
	}
    if (prefix.data != 0)
    {
	fprintf(stderr, "Xlib: out of sequence packet from server\n");
	return -1;
    }
    buf = (char *)malloc((prefix.length << 2) - sz_xReq);
    if (buf == NULL)		/* malloc failed.  Run away! */
    {
	fprintf(stderr, "Xlib: malloc bombed\n");
	return -1;
    }
    tlen = (prefix.length << 2) - sz_xReq;
    _XRead(dpy, buf, tlen);
    if (prefix.reqType == 2 && tlen < 6)
    {
	fprintf(stderr, "Xlib: stage 0 reply from server too short\n");
	free(buf);
	return -1;
    }
    if (prefix.reqType == 2)
    {
	plen = *(CARD16 *)buf;
	kbuf.data = buf + 2;
	kbuf.length = (plen > tlen) ? tlen : plen;
    }
    else
    {
	kbuf.data = buf;
	kbuf.length = tlen;
    }
    if (retval = k5_decode(kbuf, &sprinc))
    {
	free(buf);
	fprintf(stderr, "Xlib: k5_decode bombed\n");
	return -1;
    }
    if (prefix.reqType == 3)	/* do some special stuff here */
    {
	char *sname, *hostname = NULL;

	sname = (char *)malloc(krb5_princ_component(sprinc, 0)->length + 1);
	if (sname == NULL)
	{
	    free(buf);
	    krb5_free_principal(sprinc);
	    fprintf(stderr, "Xlib: malloc bombed\n");
	    return -1;
	}
	bcopy(krb5_princ_component(sprinc, 0)->data, sname,
	      krb5_princ_component(sprinc, 0)->length);
	sname[krb5_princ_component(sprinc, 0)->length] = '\0';
	krb5_free_principal(sprinc);
	if (dpy->display_name[0] != ':') /* hunt for a hostname */
	{
	    char *t;

	    if ((hostname = (char *)malloc(strlen(dpy->display_name)))
		== NULL)
	    {
		free(buf);
		free(sname);
		fprintf(stderr, "Xlib: malloc bombed\n");
		return -1;
	    }
	    strcpy(hostname, dpy->display_name);
	    t = strchr(hostname, ':');
	    if (t == NULL)
	    {
		free(buf);
		free(sname);
		free(hostname);
		fprintf(stderr,
			"Xlib: shouldn't get here! malformed display name.");
		return -1;
	    }
	    if ((t - hostname + 1 < strlen(hostname)) && t[1] == ':')
		t++;
	    *t = '\0';		/* truncate the dpy number out */
	}
	retval = krb5_sname_to_principal(hostname, sname,
					 KRB5_NT_SRV_HST, &sprinc);
	free(sname);
	if (hostname)
	    free(hostname);
	if (retval)
	{
	    free(buf);
	    fprintf(stderr, "Xlib: sname_to_principal failed: %s\n",
		    error_message(retval));
	    return -1;
	}
    }
    if (retval = krb5_cc_default(&cc))
    {
	free(buf);
	krb5_free_principal(sprinc);
	fprintf(stderr, "Xlib: cc_default failed: %s\n",
		error_message(retval));
	return -1;
    }
    if (retval = krb5_cc_get_principal(cc, &cprinc))
    {
	free(buf);
	krb5_free_principal(sprinc);
	fprintf(stderr, "Xlib: cc_get_principal failed: %s\n",
		error_message(retval));
	return -1;
    }
    bzero((char *)&creds, sizeof(creds));
    creds.server = sprinc;
    creds.client = cprinc;
    if (prefix.reqType == 2)
    {
	creds.second_ticket.length = tlen - plen - 2;
	creds.second_ticket.data = buf + 2 + plen;
	retval = krb5_get_credentials(KRB5_GC_USER_USER |
				      krb5_kdc_default_options,
				      cc, &creds);
    }
    else
	retval = krb5_get_credentials(krb5_kdc_default_options,
				      cc, &creds);
    if (retval)
    {
	free(buf);
	krb5_free_cred_contents(&creds);
	fprintf(stderr, "Xlib: get_credentials failed: %s\n",
		error_message(retval));
	return -1;
    }
    /*
     * now format the ap_req to send to the server
     */
    if (prefix.reqType == 2)
	retval = krb5_mk_req_extended(AP_OPTS_USE_SESSION_KEY |
				      AP_OPTS_MUTUAL_REQUIRED, NULL,
				      0, 0, NULL, cc,
				      &creds, NULL, &kbuf);
    else
	retval = krb5_mk_req_extended(AP_OPTS_MUTUAL_REQUIRED, NULL,
				      0, 0, NULL, cc, &creds, NULL,
				      &kbuf);
    free(buf);
    if (retval)			/* Some manner of Kerberos lossage */
    {
	krb5_free_cred_contents(&creds);
	fprintf(stderr, "Xlib: mk_req_extended failed: %s\n",
		error_message(retval));
	return -1;
    }
    prefix.reqType = 1;
    prefix.data = 0;
    prefix.length = (kbuf.length + sz_xReq + 3) >> 2;
    /*
     * stage 1: send ap_req to server
     */
    _XSend(dpy, (char *)&prefix, sz_xReq);
    _XSend(dpy, (char *)kbuf.data, kbuf.length);
    free(kbuf.data);
    /*
     * stage 2: get ap_rep from server to mutually authenticate
     */
    _XRead(dpy, (char *)&prefix, sz_xReq);
    if (prefix.reqType != 2)
	if (prefix.reqType == 0 || prefix.reqType == 1)
	{
	    bcopy((char *)&prefix, (char *)sprefix, sz_xReq);
	    _XRead(dpy, (char *)sprefix + sz_xReq,
		   sz_xConnSetupPrefix - sz_xReq);
	    return 1;
	}
	else
	{
	    fprintf(stderr, "Xlib: server is royally confused\n");
	    return -1;
	}
    if (prefix.data != 2)
	return -1;
    kbuf.length = (prefix.length << 2) - sz_xReq;
    kbuf.data = (char *)malloc(kbuf.length);
    if (kbuf.data == NULL)
    {
	fprintf(stderr, "Xlib: malloc bombed\n");
	return -1;
    }
    _XRead(dpy, (char *)kbuf.data, kbuf.length);
    retval = krb5_rd_rep(&kbuf, &creds.keyblock, &repl);
    if (retval)
    {
	free(kbuf.data);
	fprintf(stderr, "Xlib: rd_rep failed: %s\n",
		error_message(retval));
	return -1;
    }
    free(kbuf.data);
    /*
     * stage 3: send a short ack to the server and return
     */
    prefix.reqType = 3;
    prefix.data = 0;
    prefix.length = sz_xReq >> 2;
    _XSend(dpy, (char *)&prefix, sz_xReq);
    return 0;
}