FIFTH ATTEMPT at getting full-screen mode right. This new attempt

[u/mdw/putty] / pageant.c

/*
 * Pageant: the PuTTY Authentication Agent.
 */

#include <windows.h>
#ifndef NO_SECURITY
#include <aclapi.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <tchar.h>

#include "ssh.h"
#include "tree234.h"

#define IDI_MAINICON 200
#define IDI_TRAYICON 201

#define WM_XUSER     (WM_USER + 0x2000)
#define WM_SYSTRAY   (WM_XUSER + 6)
#define WM_SYSTRAY2  (WM_XUSER + 7)

#define AGENT_COPYDATA_ID 0x804e50ba   /* random goop */

/*
 * FIXME: maybe some day we can sort this out ...
 */
#define AGENT_MAX_MSGLEN  8192

#define IDM_CLOSE    0x0010
#define IDM_VIEWKEYS 0x0020
#define IDM_ADDKEY   0x0030
#define IDM_ABOUT    0x0040

#define APPNAME "Pageant"

extern char ver[];

static HINSTANCE instance;
static HWND hwnd;
static HWND keylist;
static HWND aboutbox;
static HMENU systray_menu;
static int already_running;

static tree234 *rsakeys, *ssh2keys;

static int has_security;
#ifndef NO_SECURITY
typedef DWORD(WINAPI * gsi_fn_t)
 (HANDLE, SE_OBJECT_TYPE, SECURITY_INFORMATION,
  PSID *, PSID *, PACL *, PACL *, PSECURITY_DESCRIPTOR *);
static gsi_fn_t getsecurityinfo;
#endif

/*
 * Exports from pageantc.c
 */
void agent_query(void *in, int inlen, void **out, int *outlen);
int agent_exists(void);

/*
 * We need this to link with the RSA code, because rsaencrypt()
 * pads its data with random bytes. Since we only use rsadecrypt()
 * and the signing functions, which are deterministic, this should
 * never be called.
 *
 * If it _is_ called, there is a _serious_ problem, because it
 * won't generate true random numbers. So we must scream, panic,
 * and exit immediately if that should happen.
 */
int random_byte(void)
{
    MessageBox(hwnd, "Internal Error", APPNAME, MB_OK | MB_ICONERROR);
    exit(0);
    /* this line can't be reached but it placates MSVC's warnings :-) */
    return 0;
}

/*
 * Blob structure for passing to the asymmetric SSH2 key compare
 * function, prototyped here.
 */
struct blob {
    unsigned char *blob;
    int len;
};
static int cmpkeys_ssh2_asymm(void *av, void *bv);

/*
 * This function is needed to link with the DES code. We need not
 * have it do anything at all.
 */
void logevent(char *msg)
{
}

#define GET_32BIT(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(cp, value) { \
    (cp)[0] = (unsigned char)((value) >> 24); \
    (cp)[1] = (unsigned char)((value) >> 16); \
    (cp)[2] = (unsigned char)((value) >> 8); \
    (cp)[3] = (unsigned char)(value); }

#define PASSPHRASE_MAXLEN 512

struct PassphraseProcStruct {
    char *passphrase;
    char *comment;
};

/*
 * Dialog-box function for the Licence box.
 */
static int CALLBACK LicenceProc(HWND hwnd, UINT msg,
				WPARAM wParam, LPARAM lParam)
{
    switch (msg) {
      case WM_INITDIALOG:
	return 1;
      case WM_COMMAND:
	switch (LOWORD(wParam)) {
	  case IDOK:
	    EndDialog(hwnd, 1);
	    return 0;
	}
	return 0;
      case WM_CLOSE:
	EndDialog(hwnd, 1);
	return 0;
    }
    return 0;
}

/*
 * Dialog-box function for the About box.
 */
static int CALLBACK AboutProc(HWND hwnd, UINT msg,
			      WPARAM wParam, LPARAM lParam)
{
    switch (msg) {
      case WM_INITDIALOG:
	SetDlgItemText(hwnd, 100, ver);
	return 1;
      case WM_COMMAND:
	switch (LOWORD(wParam)) {
	  case IDOK:
	    aboutbox = NULL;
	    DestroyWindow(hwnd);
	    return 0;
	  case 101:
	    EnableWindow(hwnd, 0);
	    DialogBox(instance, MAKEINTRESOURCE(214), NULL, LicenceProc);
	    EnableWindow(hwnd, 1);
	    SetActiveWindow(hwnd);
	    return 0;
	}
	return 0;
      case WM_CLOSE:
	aboutbox = NULL;
	DestroyWindow(hwnd);
	return 0;
    }
    return 0;
}

static HWND passphrase_box;

/*
 * Dialog-box function for the passphrase box.
 */
static int CALLBACK PassphraseProc(HWND hwnd, UINT msg,
				   WPARAM wParam, LPARAM lParam)
{
    static char *passphrase = NULL;
    struct PassphraseProcStruct *p;

    switch (msg) {
      case WM_INITDIALOG:
	passphrase_box = hwnd;
	/*
	 * Centre the window.
	 */
	{			       /* centre the window */
	    RECT rs, rd;
	    HWND hw;

	    hw = GetDesktopWindow();
	    if (GetWindowRect(hw, &rs) && GetWindowRect(hwnd, &rd))
		MoveWindow(hwnd,
			   (rs.right + rs.left + rd.left - rd.right) / 2,
			   (rs.bottom + rs.top + rd.top - rd.bottom) / 2,
			   rd.right - rd.left, rd.bottom - rd.top, TRUE);
	}

	SetForegroundWindow(hwnd);
	SetWindowPos(hwnd, HWND_TOP, 0, 0, 0, 0,
		     SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
	p = (struct PassphraseProcStruct *) lParam;
	passphrase = p->passphrase;
	if (p->comment)
	    SetDlgItemText(hwnd, 101, p->comment);
	*passphrase = 0;
	SetDlgItemText(hwnd, 102, passphrase);
	return 0;
      case WM_COMMAND:
	switch (LOWORD(wParam)) {
	  case IDOK:
	    if (*passphrase)
		EndDialog(hwnd, 1);
	    else
		MessageBeep(0);
	    return 0;
	  case IDCANCEL:
	    EndDialog(hwnd, 0);
	    return 0;
	  case 102:		       /* edit box */
	    if ((HIWORD(wParam) == EN_CHANGE) && passphrase) {
		GetDlgItemText(hwnd, 102, passphrase,
			       PASSPHRASE_MAXLEN - 1);
		passphrase[PASSPHRASE_MAXLEN - 1] = '\0';
	    }
	    return 0;
	}
	return 0;
      case WM_CLOSE:
	EndDialog(hwnd, 0);
	return 0;
    }
    return 0;
}

/*
 * Warn about the obsolescent key file format.
 */
void old_keyfile_warning(void)
{
    static const char mbtitle[] = "PuTTY Key File Warning";
    static const char message[] =
	"You are loading an SSH 2 private key which has an\n"
	"old version of the file format. This means your key\n"
	"file is not fully tamperproof. Future versions of\n"
	"PuTTY may stop supporting this private key format,\n"
	"so we recommend you convert your key to the new\n"
	"format.\n"
	"\n"
	"You can perform this conversion by loading the key\n"
	"into PuTTYgen and then saving it again.";

    MessageBox(NULL, message, mbtitle, MB_OK);
}

/*
 * Update the visible key list.
 */
static void keylist_update(void)
{
    struct RSAKey *rkey;
    struct ssh2_userkey *skey;
    int i;

    if (keylist) {
	SendDlgItemMessage(keylist, 100, LB_RESETCONTENT, 0, 0);
	for (i = 0; NULL != (rkey = index234(rsakeys, i)); i++) {
	    char listentry[512], *p;
	    /*
	     * Replace two spaces in the fingerprint with tabs, for
	     * nice alignment in the box.
	     */
	    strcpy(listentry, "ssh1\t");
	    p = listentry + strlen(listentry);
	    rsa_fingerprint(p, sizeof(listentry) - (p - listentry), rkey);
	    p = strchr(listentry, ' ');
	    if (p)
		*p = '\t';
	    p = strchr(listentry, ' ');
	    if (p)
		*p = '\t';
	    SendDlgItemMessage(keylist, 100, LB_ADDSTRING,
			       0, (LPARAM) listentry);
	}
	for (i = 0; NULL != (skey = index234(ssh2keys, i)); i++) {
	    char listentry[512], *p;
	    int len;
	    /*
	     * Replace two spaces in the fingerprint with tabs, for
	     * nice alignment in the box.
	     */
	    p = skey->alg->fingerprint(skey->data);
	    strncpy(listentry, p, sizeof(listentry));
	    p = strchr(listentry, ' ');
	    if (p)
		*p = '\t';
	    p = strchr(listentry, ' ');
	    if (p)
		*p = '\t';
	    len = strlen(listentry);
	    if (len < sizeof(listentry) - 2) {
		listentry[len] = '\t';
		strncpy(listentry + len + 1, skey->comment,
			sizeof(listentry) - len - 1);
	    }
	    SendDlgItemMessage(keylist, 100, LB_ADDSTRING, 0,
			       (LPARAM) listentry);
	}
	SendDlgItemMessage(keylist, 100, LB_SETCURSEL, (WPARAM) - 1, 0);
    }
}

/*
 * This function loads a key from a file and adds it.
 */
static void add_keyfile(char *filename)
{
    char passphrase[PASSPHRASE_MAXLEN];
    struct RSAKey *rkey = NULL;
    struct ssh2_userkey *skey = NULL;
    int needs_pass;
    int ret;
    int attempts;
    char *comment;
    struct PassphraseProcStruct pps;
    int ver;

    ver = keyfile_version(filename);
    if (ver == 0) {
	MessageBox(NULL, "Couldn't load private key.", APPNAME,
		   MB_OK | MB_ICONERROR);
	return;
    }

    if (ver == 1)
	needs_pass = rsakey_encrypted(filename, &comment);
    else
	needs_pass = ssh2_userkey_encrypted(filename, &comment);
    attempts = 0;
    if (ver == 1)
	rkey = smalloc(sizeof(*rkey));
    pps.passphrase = passphrase;
    pps.comment = comment;
    do {
	if (needs_pass) {
	    int dlgret;
	    dlgret = DialogBoxParam(instance, MAKEINTRESOURCE(210),
				    NULL, PassphraseProc, (LPARAM) & pps);
	    passphrase_box = NULL;
	    if (!dlgret) {
		if (comment)
		    sfree(comment);
		if (ver == 1)
		    sfree(rkey);
		return;		       /* operation cancelled */
	    }
	} else
	    *passphrase = '\0';
	if (ver == 1)
	    ret = loadrsakey(filename, rkey, passphrase);
	else {
	    skey = ssh2_load_userkey(filename, passphrase);
	    if (skey == SSH2_WRONG_PASSPHRASE)
		ret = -1;
	    else if (!skey)
		ret = 0;
	    else
		ret = 1;
	}
	attempts++;
    } while (ret == -1);
    if (comment)
	sfree(comment);
    if (ret == 0) {
	MessageBox(NULL, "Couldn't load private key.", APPNAME,
		   MB_OK | MB_ICONERROR);
	if (ver == 1)
	    sfree(rkey);
	return;
    }
    if (ver == 1) {
	if (already_running) {
	    unsigned char *request, *response;
	    void *vresponse;
	    int reqlen, clen, resplen;

	    clen = strlen(rkey->comment);

	    reqlen = 4 + 1 +	       /* length, message type */
		4 +		       /* bit count */
		ssh1_bignum_length(rkey->modulus) +
		ssh1_bignum_length(rkey->exponent) +
		ssh1_bignum_length(rkey->private_exponent) +
		ssh1_bignum_length(rkey->iqmp) +
		ssh1_bignum_length(rkey->p) +
		ssh1_bignum_length(rkey->q) + 4 + clen	/* comment */
		;

	    request = smalloc(reqlen);

	    request[4] = SSH1_AGENTC_ADD_RSA_IDENTITY;
	    reqlen = 5;
	    PUT_32BIT(request + reqlen, bignum_bitcount(rkey->modulus));
	    reqlen += 4;
	    reqlen += ssh1_write_bignum(request + reqlen, rkey->modulus);
	    reqlen += ssh1_write_bignum(request + reqlen, rkey->exponent);
	    reqlen +=
		ssh1_write_bignum(request + reqlen,
				  rkey->private_exponent);
	    reqlen += ssh1_write_bignum(request + reqlen, rkey->iqmp);
	    reqlen += ssh1_write_bignum(request + reqlen, rkey->p);
	    reqlen += ssh1_write_bignum(request + reqlen, rkey->q);
	    PUT_32BIT(request + reqlen, clen);
	    memcpy(request + reqlen + 4, rkey->comment, clen);
	    reqlen += 4 + clen;
	    PUT_32BIT(request, reqlen - 4);

	    agent_query(request, reqlen, &vresponse, &resplen);
	    response = vresponse;
	    if (resplen < 5 || response[4] != SSH_AGENT_SUCCESS)
		MessageBox(NULL, "The already running Pageant "
			   "refused to add the key.", APPNAME,
			   MB_OK | MB_ICONERROR);
	} else {
	    if (add234(rsakeys, rkey) != rkey)
		sfree(rkey);	       /* already present, don't waste RAM */
	}
    } else {
	if (already_running) {
	    unsigned char *request, *response;
	    void *vresponse;
	    int reqlen, alglen, clen, keybloblen, resplen;
	    alglen = strlen(skey->alg->name);
	    clen = strlen(skey->comment);

	    keybloblen = skey->alg->openssh_fmtkey(skey->data, NULL, 0);

	    reqlen = 4 + 1 +	       /* length, message type */
		4 + alglen +	       /* algorithm name */
		keybloblen +	       /* key data */
		4 + clen	       /* comment */
		;

	    request = smalloc(reqlen);

	    request[4] = SSH2_AGENTC_ADD_IDENTITY;
	    reqlen = 5;
	    PUT_32BIT(request + reqlen, alglen);
	    reqlen += 4;
	    memcpy(request + reqlen, skey->alg->name, alglen);
	    reqlen += alglen;
	    reqlen += skey->alg->openssh_fmtkey(skey->data,
						request + reqlen,
						keybloblen);
	    PUT_32BIT(request + reqlen, clen);
	    memcpy(request + reqlen + 4, skey->comment, clen);
	    PUT_32BIT(request, reqlen - 4);
	    reqlen += clen + 4;

	    agent_query(request, reqlen, &vresponse, &resplen);
	    response = vresponse;
	    if (resplen < 5 || response[4] != SSH_AGENT_SUCCESS)
		MessageBox(NULL, "The already running Pageant"
			   "refused to add the key.", APPNAME,
			   MB_OK | MB_ICONERROR);
	} else {
	    if (add234(ssh2keys, skey) != skey) {
		skey->alg->freekey(skey->data);
		sfree(skey);	       /* already present, don't waste RAM */
	    }
	}
    }
}

/*
 * This is the main agent function that answers messages.
 */
static void answer_msg(void *msg)
{
    unsigned char *p = msg;
    unsigned char *ret = msg;
    int type;

    /*
     * Get the message type.
     */
    type = p[4];

    p += 5;
    switch (type) {
      case SSH1_AGENTC_REQUEST_RSA_IDENTITIES:
	/*
	 * Reply with SSH1_AGENT_RSA_IDENTITIES_ANSWER.
	 */
	{
	    struct RSAKey *key;
	    int len, nkeys;
	    int i;

	    /*
	     * Count up the number and length of keys we hold.
	     */
	    len = nkeys = 0;
	    for (i = 0; NULL != (key = index234(rsakeys, i)); i++) {
		nkeys++;
		len += 4;	       /* length field */
		len += ssh1_bignum_length(key->exponent);
		len += ssh1_bignum_length(key->modulus);
		len += 4 + strlen(key->comment);
	    }

	    /*
	     * Packet header is the obvious five bytes, plus four
	     * bytes for the key count.
	     */
	    len += 5 + 4;
	    if (len > AGENT_MAX_MSGLEN)
		goto failure;	       /* aaargh! too much stuff! */
	    PUT_32BIT(ret, len - 4);
	    ret[4] = SSH1_AGENT_RSA_IDENTITIES_ANSWER;
	    PUT_32BIT(ret + 5, nkeys);
	    p = ret + 5 + 4;
	    for (i = 0; NULL != (key = index234(rsakeys, i)); i++) {
		PUT_32BIT(p, bignum_bitcount(key->modulus));
		p += 4;
		p += ssh1_write_bignum(p, key->exponent);
		p += ssh1_write_bignum(p, key->modulus);
		PUT_32BIT(p, strlen(key->comment));
		memcpy(p + 4, key->comment, strlen(key->comment));
		p += 4 + strlen(key->comment);
	    }
	}
	break;
      case SSH2_AGENTC_REQUEST_IDENTITIES:
	/*
	 * Reply with SSH2_AGENT_IDENTITIES_ANSWER.
	 */
	{
	    struct ssh2_userkey *key;
	    int len, nkeys;
	    unsigned char *blob;
	    int bloblen;
	    int i;

	    /*
	     * Count up the number and length of keys we hold.
	     */
	    len = nkeys = 0;
	    for (i = 0; NULL != (key = index234(ssh2keys, i)); i++) {
		nkeys++;
		len += 4;	       /* length field */
		blob = key->alg->public_blob(key->data, &bloblen);
		len += bloblen;
		sfree(blob);
		len += 4 + strlen(key->comment);
	    }

	    /*
	     * Packet header is the obvious five bytes, plus four
	     * bytes for the key count.
	     */
	    len += 5 + 4;
	    if (len > AGENT_MAX_MSGLEN)
		goto failure;	       /* aaargh! too much stuff! */
	    PUT_32BIT(ret, len - 4);
	    ret[4] = SSH2_AGENT_IDENTITIES_ANSWER;
	    PUT_32BIT(ret + 5, nkeys);
	    p = ret + 5 + 4;
	    for (i = 0; NULL != (key = index234(ssh2keys, i)); i++) {
		blob = key->alg->public_blob(key->data, &bloblen);
		PUT_32BIT(p, bloblen);
		p += 4;
		memcpy(p, blob, bloblen);
		p += bloblen;
		sfree(blob);
		PUT_32BIT(p, strlen(key->comment));
		memcpy(p + 4, key->comment, strlen(key->comment));
		p += 4 + strlen(key->comment);
	    }
	}
	break;
      case SSH1_AGENTC_RSA_CHALLENGE:
	/*
	 * Reply with either SSH1_AGENT_RSA_RESPONSE or
	 * SSH_AGENT_FAILURE, depending on whether we have that key
	 * or not.
	 */
	{
	    struct RSAKey reqkey, *key;
	    Bignum challenge, response;
	    unsigned char response_source[48], response_md5[16];
	    struct MD5Context md5c;
	    int i, len;

	    p += 4;
	    p += ssh1_read_bignum(p, &reqkey.exponent);
	    p += ssh1_read_bignum(p, &reqkey.modulus);
	    p += ssh1_read_bignum(p, &challenge);
	    memcpy(response_source + 32, p, 16);
	    p += 16;
	    if (GET_32BIT(p) != 1 ||
		(key = find234(rsakeys, &reqkey, NULL)) == NULL) {
		freebn(reqkey.exponent);
		freebn(reqkey.modulus);
		freebn(challenge);
		goto failure;
	    }
	    response = rsadecrypt(challenge, key);
	    for (i = 0; i < 32; i++)
		response_source[i] = bignum_byte(response, 31 - i);

	    MD5Init(&md5c);
	    MD5Update(&md5c, response_source, 48);
	    MD5Final(response_md5, &md5c);
	    memset(response_source, 0, 48);	/* burn the evidence */
	    freebn(response);	       /* and that evidence */
	    freebn(challenge);	       /* yes, and that evidence */
	    freebn(reqkey.exponent);   /* and free some memory ... */
	    freebn(reqkey.modulus);    /* ... while we're at it. */

	    /*
	     * Packet is the obvious five byte header, plus sixteen
	     * bytes of MD5.
	     */
	    len = 5 + 16;
	    PUT_32BIT(ret, len - 4);
	    ret[4] = SSH1_AGENT_RSA_RESPONSE;
	    memcpy(ret + 5, response_md5, 16);
	}
	break;
      case SSH2_AGENTC_SIGN_REQUEST:
	/*
	 * Reply with either SSH2_AGENT_SIGN_RESPONSE or
	 * SSH_AGENT_FAILURE, depending on whether we have that key
	 * or not.
	 */
	{
	    struct ssh2_userkey *key;
	    struct blob b;
	    unsigned char *data, *signature;
	    int datalen, siglen, len;

	    b.len = GET_32BIT(p);
	    p += 4;
	    b.blob = p;
	    p += b.len;
	    datalen = GET_32BIT(p);
	    p += 4;
	    data = p;
	    key = find234(ssh2keys, &b, cmpkeys_ssh2_asymm);
	    if (!key)
		goto failure;
	    signature = key->alg->sign(key->data, data, datalen, &siglen);
	    len = 5 + 4 + siglen;
	    PUT_32BIT(ret, len - 4);
	    ret[4] = SSH2_AGENT_SIGN_RESPONSE;
	    PUT_32BIT(ret + 5, siglen);
	    memcpy(ret + 5 + 4, signature, siglen);
	    sfree(signature);
	}
	break;
      case SSH1_AGENTC_ADD_RSA_IDENTITY:
	/*
	 * Add to the list and return SSH_AGENT_SUCCESS, or
	 * SSH_AGENT_FAILURE if the key was malformed.
	 */
	{
	    struct RSAKey *key;
	    char *comment;
            int commentlen;
	    key = smalloc(sizeof(struct RSAKey));
	    memset(key, 0, sizeof(struct RSAKey));
	    p += makekey(p, key, NULL, 1);
	    p += makeprivate(p, key);
	    p += ssh1_read_bignum(p, &key->iqmp);	/* p^-1 mod q */
	    p += ssh1_read_bignum(p, &key->p);	/* p */
	    p += ssh1_read_bignum(p, &key->q);	/* q */
            commentlen = GET_32BIT(p);
	    comment = smalloc(commentlen+1);
	    if (comment) {
		memcpy(comment, p + 4, commentlen);
                comment[commentlen] = '\0';
		key->comment = comment;
	    }
	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_FAILURE;
	    if (add234(rsakeys, key) == key) {
		keylist_update();
		ret[4] = SSH_AGENT_SUCCESS;
	    } else {
		freersakey(key);
		sfree(key);
	    }
	}
	break;
      case SSH2_AGENTC_ADD_IDENTITY:
	/*
	 * Add to the list and return SSH_AGENT_SUCCESS, or
	 * SSH_AGENT_FAILURE if the key was malformed.
	 */
	{
	    struct ssh2_userkey *key;
	    char *comment, *alg;
	    int alglen, commlen;
	    int bloblen;

	    key = smalloc(sizeof(struct ssh2_userkey));

	    alglen = GET_32BIT(p);
	    p += 4;
	    alg = p;
	    p += alglen;
	    /* Add further algorithm names here. */
	    if (alglen == 7 && !memcmp(alg, "ssh-rsa", 7))
		key->alg = &ssh_rsa;
	    else if (alglen == 7 && !memcmp(alg, "ssh-dss", 7))
		key->alg = &ssh_dss;
	    else {
		sfree(key);
		goto failure;
	    }

	    bloblen =
		GET_32BIT((unsigned char *) msg) - (p -
						    (unsigned char *) msg -
						    4);
	    key->data = key->alg->openssh_createkey(&p, &bloblen);
	    if (!key->data) {
		sfree(key);
		goto failure;
	    }
	    commlen = GET_32BIT(p);
	    p += 4;

	    comment = smalloc(commlen + 1);
	    if (comment) {
		memcpy(comment, p, commlen);
		comment[commlen] = '\0';
	    }
	    key->comment = comment;

	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_FAILURE;
	    if (add234(ssh2keys, key) == key) {
		keylist_update();
		ret[4] = SSH_AGENT_SUCCESS;
	    } else {
		key->alg->freekey(key->data);
		sfree(key->comment);
		sfree(key);
	    }
	}
	break;
      case SSH1_AGENTC_REMOVE_RSA_IDENTITY:
	/*
	 * Remove from the list and return SSH_AGENT_SUCCESS, or
	 * perhaps SSH_AGENT_FAILURE if it wasn't in the list to
	 * start with.
	 */
	{
	    struct RSAKey reqkey, *key;

	    p += makekey(p, &reqkey, NULL, 0);
	    key = find234(rsakeys, &reqkey, NULL);
	    freebn(reqkey.exponent);
	    freebn(reqkey.modulus);
	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_FAILURE;
	    if (key) {
		del234(rsakeys, key);
		keylist_update();
		freersakey(key);
		sfree(key);
		ret[4] = SSH_AGENT_SUCCESS;
	    }
	}
	break;
      case SSH2_AGENTC_REMOVE_IDENTITY:
	/*
	 * Remove from the list and return SSH_AGENT_SUCCESS, or
	 * perhaps SSH_AGENT_FAILURE if it wasn't in the list to
	 * start with.
	 */
	{
	    struct ssh2_userkey *key;
	    struct blob b;

	    b.len = GET_32BIT(p);
	    p += 4;
	    b.blob = p;
	    p += b.len;
	    key = find234(ssh2keys, &b, cmpkeys_ssh2_asymm);
	    if (!key)
		goto failure;

	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_FAILURE;
	    if (key) {
		del234(ssh2keys, key);
		keylist_update();
		key->alg->freekey(key->data);
		sfree(key);
		ret[4] = SSH_AGENT_SUCCESS;
	    }
	}
	break;
      case SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
	/*
	 * Remove all SSH1 keys. Always returns success.
	 */
	{
	    struct RSAKey *rkey;

	    while ((rkey = index234(rsakeys, 0)) != NULL) {
		del234(rsakeys, rkey);
		freersakey(rkey);
		sfree(rkey);
	    }
	    keylist_update();

	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_SUCCESS;
	}
	break;
      case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
	/*
	 * Remove all SSH2 keys. Always returns success.
	 */
	{
	    struct ssh2_userkey *skey;

	    while ((skey = index234(ssh2keys, 0)) != NULL) {
		del234(ssh2keys, skey);
		skey->alg->freekey(skey->data);
		sfree(skey);
	    }
	    keylist_update();

	    PUT_32BIT(ret, 1);
	    ret[4] = SSH_AGENT_SUCCESS;
	}
	break;
      default:
      failure:
	/*
	 * Unrecognised message. Return SSH_AGENT_FAILURE.
	 */
	PUT_32BIT(ret, 1);
	ret[4] = SSH_AGENT_FAILURE;
	break;
    }
}

/*
 * Key comparison function for the 2-3-4 tree of RSA keys.
 */
static int cmpkeys_rsa(void *av, void *bv)
{
    struct RSAKey *a = (struct RSAKey *) av;
    struct RSAKey *b = (struct RSAKey *) bv;
    Bignum am, bm;
    int alen, blen;

    am = a->modulus;
    bm = b->modulus;
    /*
     * Compare by length of moduli.
     */
    alen = bignum_bitcount(am);
    blen = bignum_bitcount(bm);
    if (alen > blen)
	return +1;
    else if (alen < blen)
	return -1;
    /*
     * Now compare by moduli themselves.
     */
    alen = (alen + 7) / 8;	       /* byte count */
    while (alen-- > 0) {
	int abyte, bbyte;
	abyte = bignum_byte(am, alen);
	bbyte = bignum_byte(bm, alen);
	if (abyte > bbyte)
	    return +1;
	else if (abyte < bbyte)
	    return -1;
    }
    /*
     * Give up.
     */
    return 0;
}

/*
 * Key comparison function for the 2-3-4 tree of SSH2 keys.
 */
static int cmpkeys_ssh2(void *av, void *bv)
{
    struct ssh2_userkey *a = (struct ssh2_userkey *) av;
    struct ssh2_userkey *b = (struct ssh2_userkey *) bv;
    int i;
    int alen, blen;
    unsigned char *ablob, *bblob;
    int c;

    /*
     * Compare purely by public blob.
     */
    ablob = a->alg->public_blob(a->data, &alen);
    bblob = b->alg->public_blob(b->data, &blen);

    c = 0;
    for (i = 0; i < alen && i < blen; i++) {
	if (ablob[i] < bblob[i]) {
	    c = -1;
	    break;
	} else if (ablob[i] > bblob[i]) {
	    c = +1;
	    break;
	}
    }
    if (c == 0 && i < alen)
	c = +1;			       /* a is longer */
    if (c == 0 && i < blen)
	c = -1;			       /* a is longer */

    sfree(ablob);
    sfree(bblob);

    return c;
}

/*
 * Key comparison function for looking up a blob in the 2-3-4 tree
 * of SSH2 keys.
 */
static int cmpkeys_ssh2_asymm(void *av, void *bv)
{
    struct blob *a = (struct blob *) av;
    struct ssh2_userkey *b = (struct ssh2_userkey *) bv;
    int i;
    int alen, blen;
    unsigned char *ablob, *bblob;
    int c;

    /*
     * Compare purely by public blob.
     */
    ablob = a->blob;
    alen = a->len;
    bblob = b->alg->public_blob(b->data, &blen);

    c = 0;
    for (i = 0; i < alen && i < blen; i++) {
	if (ablob[i] < bblob[i]) {
	    c = -1;
	    break;
	} else if (ablob[i] > bblob[i]) {
	    c = +1;
	    break;
	}
    }
    if (c == 0 && i < alen)
	c = +1;			       /* a is longer */
    if (c == 0 && i < blen)
	c = -1;			       /* a is longer */

    sfree(bblob);

    return c;
}

/*
 * Prompt for a key file to add, and add it.
 */
static void prompt_add_keyfile(void)
{
    OPENFILENAME of;
    char filename[FILENAME_MAX];
    memset(&of, 0, sizeof(of));
#ifdef OPENFILENAME_SIZE_VERSION_400
    of.lStructSize = OPENFILENAME_SIZE_VERSION_400;
#else
    of.lStructSize = sizeof(of);
#endif
    of.hwndOwner = hwnd;
    of.lpstrFilter = "All Files\0*\0\0\0";
    of.lpstrCustomFilter = NULL;
    of.nFilterIndex = 1;
    of.lpstrFile = filename;
    *filename = '\0';
    of.nMaxFile = sizeof(filename);
    of.lpstrFileTitle = NULL;
    of.lpstrInitialDir = NULL;
    of.lpstrTitle = "Select Private Key File";
    of.Flags = 0;
    if (GetOpenFileName(&of)) {
	add_keyfile(filename);
	keylist_update();
    }
}

/*
 * Dialog-box function for the key list box.
 */
static int CALLBACK KeyListProc(HWND hwnd, UINT msg,
				WPARAM wParam, LPARAM lParam)
{
    struct RSAKey *rkey;
    struct ssh2_userkey *skey;

    switch (msg) {
      case WM_INITDIALOG:
	/*
	 * Centre the window.
	 */
	{			       /* centre the window */
	    RECT rs, rd;
	    HWND hw;

	    hw = GetDesktopWindow();
	    if (GetWindowRect(hw, &rs) && GetWindowRect(hwnd, &rd))
		MoveWindow(hwnd,
			   (rs.right + rs.left + rd.left - rd.right) / 2,
			   (rs.bottom + rs.top + rd.top - rd.bottom) / 2,
			   rd.right - rd.left, rd.bottom - rd.top, TRUE);
	}

	keylist = hwnd;
	{
	    static int tabs[] = { 35, 60, 210 };
	    SendDlgItemMessage(hwnd, 100, LB_SETTABSTOPS,
			       sizeof(tabs) / sizeof(*tabs),
			       (LPARAM) tabs);
	}
	keylist_update();
	return 0;
      case WM_COMMAND:
	switch (LOWORD(wParam)) {
	  case IDOK:
	  case IDCANCEL:
	    keylist = NULL;
	    DestroyWindow(hwnd);
	    return 0;
	  case 101:		       /* add key */
	    if (HIWORD(wParam) == BN_CLICKED ||
		HIWORD(wParam) == BN_DOUBLECLICKED) {
		if (passphrase_box) {
		    MessageBeep(MB_ICONERROR);
		    SetForegroundWindow(passphrase_box);
		    break;
		}
		prompt_add_keyfile();
	    }
	    return 0;
	  case 102:		       /* remove key */
	    if (HIWORD(wParam) == BN_CLICKED ||
		HIWORD(wParam) == BN_DOUBLECLICKED) {
		int n = SendDlgItemMessage(hwnd, 100, LB_GETCURSEL, 0, 0);
		int i;
		if (n == LB_ERR) {
		    MessageBeep(0);
		    break;
		}
		for (i = 0; NULL != (rkey = index234(rsakeys, i)); i++)
		    if (n-- == 0)
			break;
		if (rkey) {
		    del234(rsakeys, rkey);
		    freersakey(rkey);
		    sfree(rkey);
		} else {
		    for (i = 0; NULL != (skey = index234(ssh2keys, i));
			 i++) if (n-- == 0)
			    break;
		    if (skey) {
			del234(ssh2keys, skey);
			skey->alg->freekey(skey->data);
			sfree(skey);
		    }
		}
		keylist_update();
	    }
	    return 0;
	}
	return 0;
      case WM_CLOSE:
	keylist = NULL;
	DestroyWindow(hwnd);
	return 0;
    }
    return 0;
}

/* Set up a system tray icon */
static BOOL AddTrayIcon(HWND hwnd)
{
    BOOL res;
    NOTIFYICONDATA tnid;
    HICON hicon;

#ifdef NIM_SETVERSION
    tnid.uVersion = 0;
    res = Shell_NotifyIcon(NIM_SETVERSION, &tnid);
#endif

    tnid.cbSize = sizeof(NOTIFYICONDATA);
    tnid.hWnd = hwnd;
    tnid.uID = 1;	       /* unique within this systray use */
    tnid.uFlags = NIF_MESSAGE | NIF_ICON | NIF_TIP;
    tnid.uCallbackMessage = WM_SYSTRAY;
    tnid.hIcon = hicon = LoadIcon(instance, MAKEINTRESOURCE(201));
    strcpy(tnid.szTip, "Pageant (PuTTY authentication agent)");

    res = Shell_NotifyIcon(NIM_ADD, &tnid);

    if (hicon) DestroyIcon(hicon);
    
    return res;
}

static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
				WPARAM wParam, LPARAM lParam)
{
    int ret;
    static int menuinprogress;
    static UINT msgTaskbarCreated = 0;

    switch (message) {
      case WM_CREATE:
        msgTaskbarCreated = RegisterWindowMessage(_T("TaskbarCreated"));
        break;
      default:
        if (message==msgTaskbarCreated) {
            /*
	     * Explorer has been restarted, so the tray icon will
	     * have been lost.
	     */
	    AddTrayIcon(hwnd);
        }
        break;
        
      case WM_SYSTRAY:
	if (lParam == WM_RBUTTONUP) {
	    POINT cursorpos;
	    GetCursorPos(&cursorpos);
	    PostMessage(hwnd, WM_SYSTRAY2, cursorpos.x, cursorpos.y);
	} else if (lParam == WM_LBUTTONDBLCLK) {
	    /* Equivalent to IDM_VIEWKEYS. */
	    PostMessage(hwnd, WM_COMMAND, IDM_VIEWKEYS, 0);
	}
	break;
      case WM_SYSTRAY2:
	if (!menuinprogress) {
	    menuinprogress = 1;
	    SetForegroundWindow(hwnd);
	    ret = TrackPopupMenu(systray_menu,
				 TPM_RIGHTALIGN | TPM_BOTTOMALIGN |
				 TPM_RIGHTBUTTON,
				 wParam, lParam, 0, hwnd, NULL);
	    menuinprogress = 0;
	}
	break;
      case WM_COMMAND:
      case WM_SYSCOMMAND:
	switch (wParam & ~0xF) {       /* low 4 bits reserved to Windows */
	  case IDM_CLOSE:
	    if (passphrase_box)
		SendMessage(passphrase_box, WM_CLOSE, 0, 0);
	    SendMessage(hwnd, WM_CLOSE, 0, 0);
	    break;
	  case IDM_VIEWKEYS:
	    if (!keylist) {
		keylist = CreateDialog(instance, MAKEINTRESOURCE(211),
				       NULL, KeyListProc);
		ShowWindow(keylist, SW_SHOWNORMAL);
		/* 
		 * Sometimes the window comes up minimised / hidden
		 * for no obvious reason. Prevent this.
		 */
		SetForegroundWindow(keylist);
		SetWindowPos(keylist, HWND_TOP, 0, 0, 0, 0,
			     SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
	    }
	    break;
	  case IDM_ADDKEY:
	    if (passphrase_box) {
		MessageBeep(MB_ICONERROR);
		SetForegroundWindow(passphrase_box);
		break;
	    }
	    prompt_add_keyfile();
	    break;
	  case IDM_ABOUT:
	    if (!aboutbox) {
		aboutbox = CreateDialog(instance, MAKEINTRESOURCE(213),
					NULL, AboutProc);
		ShowWindow(aboutbox, SW_SHOWNORMAL);
		/* 
		 * Sometimes the window comes up minimised / hidden
		 * for no obvious reason. Prevent this.
		 */
		SetForegroundWindow(aboutbox);
		SetWindowPos(aboutbox, HWND_TOP, 0, 0, 0, 0,
			     SWP_NOMOVE | SWP_NOSIZE | SWP_SHOWWINDOW);
	    }
	    break;
	}
	break;
      case WM_DESTROY:
	PostQuitMessage(0);
	return 0;
      case WM_COPYDATA:
	{
	    COPYDATASTRUCT *cds;
	    char *mapname;
	    void *p;
	    HANDLE filemap;
#ifndef NO_SECURITY
	    HANDLE proc;
	    PSID mapowner, procowner;
	    PSECURITY_DESCRIPTOR psd1 = NULL, psd2 = NULL;
#endif
	    int ret = 0;

	    cds = (COPYDATASTRUCT *) lParam;
	    if (cds->dwData != AGENT_COPYDATA_ID)
		return 0;	       /* not our message, mate */
	    mapname = (char *) cds->lpData;
	    if (mapname[cds->cbData - 1] != '\0')
		return 0;	       /* failure to be ASCIZ! */
#ifdef DEBUG_IPC
	    debug(("mapname is :%s:\n", mapname));
#endif
	    filemap = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, mapname);
#ifdef DEBUG_IPC
	    debug(("filemap is %p\n", filemap));
#endif
	    if (filemap != NULL && filemap != INVALID_HANDLE_VALUE) {
#ifndef NO_SECURITY
		int rc;
		if (has_security) {
		    if ((proc = OpenProcess(MAXIMUM_ALLOWED, FALSE,
					    GetCurrentProcessId())) ==
			NULL) {
#ifdef DEBUG_IPC
			debug(("couldn't get handle for process\n"));
#endif
			return 0;
		    }
		    if (getsecurityinfo(proc, SE_KERNEL_OBJECT,
					OWNER_SECURITY_INFORMATION,
					&procowner, NULL, NULL, NULL,
					&psd2) != ERROR_SUCCESS) {
#ifdef DEBUG_IPC
			debug(("couldn't get owner info for process\n"));
#endif
			CloseHandle(proc);
			return 0;      /* unable to get security info */
		    }
		    CloseHandle(proc);
		    if ((rc = getsecurityinfo(filemap, SE_KERNEL_OBJECT,
					      OWNER_SECURITY_INFORMATION,
					      &mapowner, NULL, NULL, NULL,
					      &psd1) != ERROR_SUCCESS)) {
#ifdef DEBUG_IPC
			debug(
			      ("couldn't get owner info for filemap: %d\n",
			       rc));
#endif
			return 0;
		    }
#ifdef DEBUG_IPC
		    debug(("got security stuff\n"));
#endif
		    if (!EqualSid(mapowner, procowner))
			return 0;      /* security ID mismatch! */
#ifdef DEBUG_IPC
		    debug(("security stuff matched\n"));
#endif
		    LocalFree(psd1);
		    LocalFree(psd2);
		} else {
#ifdef DEBUG_IPC
		    debug(("security APIs not present\n"));
#endif
		}
#endif
		p = MapViewOfFile(filemap, FILE_MAP_WRITE, 0, 0, 0);
#ifdef DEBUG_IPC
		debug(("p is %p\n", p));
		{
		    int i;
		    for (i = 0; i < 5; i++)
			debug(
			      ("p[%d]=%02x\n", i,
			       ((unsigned char *) p)[i]));}
#endif
		answer_msg(p);
		ret = 1;
		UnmapViewOfFile(p);
	    }
	    CloseHandle(filemap);
	    return ret;
	}
    }

    return DefWindowProc(hwnd, message, wParam, lParam);
}

/*
 * Fork and Exec the command in cmdline. [DBW]
 */
void spawn_cmd(char *cmdline, int show)
{
    if (ShellExecute(NULL, _T("open"), cmdline,
		     NULL, NULL, show) <= (HINSTANCE) 32) {
	TCHAR sMsg[140];
	sprintf(sMsg, _T("Failed to run \"%.100s\", Error: %d"), cmdline,
		(int)GetLastError());
	MessageBox(NULL, sMsg, APPNAME, MB_OK | MB_ICONEXCLAMATION);
    }
}

int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)
{
    WNDCLASS wndclass;
    MSG msg;
    OSVERSIONINFO osi;
    HMODULE advapi;
    char *command = NULL;
    int added_keys = 0;

    /*
     * Determine whether we're an NT system (should have security
     * APIs) or a non-NT system (don't do security).
     */
    memset(&osi, 0, sizeof(OSVERSIONINFO));
    osi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
    if (GetVersionEx(&osi) && osi.dwPlatformId == VER_PLATFORM_WIN32_NT) {
	has_security = TRUE;
    } else
	has_security = FALSE;

    if (has_security) {
#ifndef NO_SECURITY
	/*
	 * Attempt to get the security API we need.
	 */
	advapi = LoadLibrary("ADVAPI32.DLL");
	getsecurityinfo =
	    (gsi_fn_t) GetProcAddress(advapi, "GetSecurityInfo");
	if (!getsecurityinfo) {
	    MessageBox(NULL,
		       "Unable to access security APIs. Pageant will\n"
		       "not run, in case it causes a security breach.",
		       "Pageant Fatal Error", MB_ICONERROR | MB_OK);
	    return 1;
	}
#else
	MessageBox(NULL,
		   "This program has been compiled for Win9X and will\n"
		   "not run on NT, in case it causes a security breach.",
		   "Pageant Fatal Error", MB_ICONERROR | MB_OK);
	return 1;
#endif
    } else
	advapi = NULL;

    instance = inst;

    /*
     * Find out if Pageant is already running.
     */
    already_running = FALSE;
    if (agent_exists())
	already_running = TRUE;
    else {

	if (!prev) {
	    wndclass.style = 0;
	    wndclass.lpfnWndProc = WndProc;
	    wndclass.cbClsExtra = 0;
	    wndclass.cbWndExtra = 0;
	    wndclass.hInstance = inst;
	    wndclass.hIcon = LoadIcon(inst, MAKEINTRESOURCE(IDI_MAINICON));
	    wndclass.hCursor = LoadCursor(NULL, IDC_IBEAM);
	    wndclass.hbrBackground = GetStockObject(BLACK_BRUSH);
	    wndclass.lpszMenuName = NULL;
	    wndclass.lpszClassName = APPNAME;

	    RegisterClass(&wndclass);
	}

	hwnd = keylist = NULL;

	hwnd = CreateWindow(APPNAME, APPNAME,
			    WS_OVERLAPPEDWINDOW | WS_VSCROLL,
			    CW_USEDEFAULT, CW_USEDEFAULT,
			    100, 100, NULL, NULL, inst, NULL);

	/* Set up a system tray icon */
	AddTrayIcon(hwnd);

        systray_menu = CreatePopupMenu();
        /* accelerators used: vkxa */
        AppendMenu(systray_menu, MF_ENABLED, IDM_VIEWKEYS,
               "&View Keys");
        AppendMenu(systray_menu, MF_ENABLED, IDM_ADDKEY, "Add &Key");
        AppendMenu(systray_menu, MF_ENABLED, IDM_ABOUT, "&About");
        AppendMenu(systray_menu, MF_ENABLED, IDM_CLOSE, "E&xit");

	ShowWindow(hwnd, SW_HIDE);

	/*
	 * Initialise storage for RSA keys.
	 */
	rsakeys = newtree234(cmpkeys_rsa);
	ssh2keys = newtree234(cmpkeys_ssh2);

    }

    /*
     * Process the command line and add keys as listed on it.
     * If we already determined that we need to spawn a program from above we
     * need to ignore the first two arguments. [DBW]
     */
    {
	char *p;
	int inquotes = 0;
	p = cmdline;
	while (*p) {
	    while (*p && isspace(*p))
		p++;
	    if (*p && !isspace(*p)) {
		char *q = p, *pp = p;
		while (*p && (inquotes || !isspace(*p))) {
		    if (*p == '"') {
			inquotes = !inquotes;
			p++;
			continue;
		    }
		    *pp++ = *p++;
		}
		if (*pp) {
		    if (*p)
			p++;
		    *pp++ = '\0';
		}
		if (!strcmp(q, "-c")) {
		    /*
		     * If we see `-c', then the rest of the
		     * command line should be treated as a
		     * command to be spawned.
		     */
		    while (*p && isspace(*p))
			p++;
		    command = p;
		    break;
		} else {
		    add_keyfile(q);
		    added_keys = TRUE;
		}
	    }
	}
    }

    if (command)
	spawn_cmd(command, show);

    /*
     * If Pageant was already running, we leave now. If we haven't
     * even taken any auxiliary action (spawned a command or added
     * keys), complain.
     */
    if (already_running) {
	if (!command && !added_keys) {
	    MessageBox(NULL, "Pageant is already running", "Pageant Error",
		       MB_ICONERROR | MB_OK);
	}
	if (advapi)
	    FreeLibrary(advapi);
	return 0;
    }

    /*
     * Main message loop.
     */
    while (GetMessage(&msg, NULL, 0, 0) == 1) {
	TranslateMessage(&msg);
	DispatchMessage(&msg);
    }

    /* Clean up the system tray icon */
    {
	NOTIFYICONDATA tnid;

	tnid.cbSize = sizeof(NOTIFYICONDATA);
	tnid.hWnd = hwnd;
	tnid.uID = 1;

	Shell_NotifyIcon(NIM_DELETE, &tnid);

	DestroyMenu(systray_menu);
    }

    if (advapi)
	FreeLibrary(advapi);
    exit(msg.wParam);
}