int ssh_write(int fd, const void *buf, size_t count)
{
    int len;
    const char *data = buf;
    int result = count;

    while (count > 0) {
        len = count > 512 ? 512 : count;
        packet_start(SSH_SMSG_STDOUT_DATA);
        packet_put_string(data, len);
        packet_send();
        packet_write_wait();
        count -= len;
        data += len;
    }
    return result;
}

void
ssh_put_password(char *password)
{
	int size;
	char *padded;

	if (datafellows & SSH_BUG_PASSWORDPAD) {
		packet_put_cstring(password);
		return;
	}
	size = ROUNDUP(strlen(password) + 1, 32);
	padded = xcalloc(1, size);
	strlcpy(padded, password, size);
	packet_put_string(padded, size);
	explicit_bzero(padded, size);
	free(padded);
}

void
ssh_put_password(char *password)
{
	int size;
	char *padded;

	if (datafellows & SSH_BUG_PASSWORDPAD) {
		packet_put_cstring(password);
		return;
	}
	size = roundup(strlen(password) + 1, 32);
	padded = xcalloc(1, size);
	strlcpy(padded, password, size);
	packet_put_string(padded, size);
	memset(padded, 0, size);
	xfree(padded);
}

/*
 * Make packets from buffered stdout data, and buffer it for sending to the
 * client.
 */
static void
make_packets_from_stdout_data(void)
{
	u_int len;

	/* Send buffered stdout data to the client. */
	while (buffer_len(&stdout_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stdout_buffer);
		if (packet_is_interactive()) {
			if (len > 512)
				len = 512;
		} else {
			/* Keep the packets at reasonable size. */
			if (len > packet_get_maxsize())
				len = packet_get_maxsize();
		}
		packet_start(SSH_SMSG_STDOUT_DATA);
		packet_put_string(buffer_ptr(&stdout_buffer), len);
		packet_send();
		buffer_consume(&stdout_buffer, len);
		stdout_bytes += len;
	}
}

static void
client_make_packets_from_stdin_data(void)
{
	u_int len;

	/* Send buffered stdin data to the server. */
	while (buffer_len(&stdin_buffer) > 0 &&
	    packet_not_very_much_data_to_write()) {
		len = buffer_len(&stdin_buffer);
		/* Keep the packets at reasonable size. */
		if (len > packet_get_maxsize())
			len = packet_get_maxsize();
		packet_start(SSH_CMSG_STDIN_DATA);
		packet_put_string(buffer_ptr(&stdin_buffer), len);
		packet_send();
		buffer_consume(&stdin_buffer, len);
		stdin_bytes += len;
		/* If we have a pending EOF, send it now. */
		if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
			packet_start(SSH_CMSG_EOF);
			packet_send();
		}
	}
}

int
userauth_gssapi_keyex(Authctxt *authctxt)
{
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok;
	OM_uint32 status;
        static int attempt = 0;
	
	if (authctxt == NULL || authctxt->method == NULL)
		fatal("input_gssapi_response: no authentication context");

	if (xxx_gssctxt == NULL || xxx_gssctxt->context == GSS_C_NO_CONTEXT)
		return 0;

	if (strcmp(authctxt->method->name, "gssapi-keyex") == 0)
		authctxt->methoddata = gssctxt = xxx_gssctxt;
	
        if (attempt++ >= 1)
        	return 0;
                                
	if (strcmp(authctxt->method->name, "gssapi-keyex") == 0) {
		gss_buffer_desc g_mic_data;
		Buffer mic_data;

		debug2("Authenticating with GSS-API context from key exchange (w/ MIC)");

		/* Make data buffer to MIC */
		buffer_init(&mic_data);
		buffer_put_string(&mic_data, session_id2, session_id2_len);
		buffer_put_char(&mic_data, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&mic_data, authctxt->server_user);
		buffer_put_cstring(&mic_data, authctxt->service);
		buffer_put_cstring(&mic_data, authctxt->method->name);

		/* Make MIC */
		g_mic_data.value  = buffer_ptr(&mic_data);
		g_mic_data.length = buffer_len(&mic_data);
		status = ssh_gssapi_get_mic(gssctxt, &g_mic_data, &send_tok);
		buffer_clear(&mic_data);

		if (GSS_ERROR(status) || send_tok.length == 0) {
			/*
			 * Oops, now what?  There's no error token...
			 * Next userauth
			 */
			debug("GSS_GetMIC() failed! - "
			      "Abandoning GSSAPI userauth");
			clear_auth_state(authctxt);
			userauth(authctxt,NULL);
			return 0;
		}
		packet_start(SSH2_MSG_USERAUTH_REQUEST);
		packet_put_cstring(authctxt->server_user);
		packet_put_cstring(authctxt->service);
		packet_put_cstring(authctxt->method->name);
		packet_put_string(send_tok.value,send_tok.length); /* MIC */
		packet_send();
		packet_write_wait();
		(void) gss_release_buffer(&status, &send_tok);
	} else if (strcmp(authctxt->method->name, "external-keyx") == 0) {
		debug2("Authentication with deprecated \"external-keyx\""
			" method not supported");
		return 0;
	}
        return 1;
}

//.........这里部分代码省略.........
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	if (key_type_plain(key->type) == KEY_RSA &&
	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
		logit("Refusing RSA key because client uses unsafe "
		    "signature scheme");
		goto done;
	}
	if (auth2_userkey_already_used(authctxt, key)) {
		logit("refusing previously-used %s key", key_type(key));
		goto done;
	}
	if (match_pattern_list(sshkey_ssh_name(key), options.pubkey_key_types,
	    strlen(options.pubkey_key_types), 0) != 1) {
		logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
		    __func__, sshkey_ssh_name(key));
		goto done;
	}

	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		xasprintf(&userstyle, "%s%s%s", authctxt->user,
		    authctxt->style ? ":" : "",
		    authctxt->style ? authctxt->style : "");
		buffer_put_cstring(&b, userstyle);
		free(userstyle);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		pubkey_auth_info(authctxt, key, NULL);

		/* test for correct signature */
		authenticated = 0;
		if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b))) == 1) {
			authenticated = 1;
			/* Record the successful key to prevent reuse */
			auth2_record_userkey(authctxt, key);
			key = NULL; /* Don't free below */
		}
		buffer_free(&b);
		free(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->postponed = 1;
		}
	}
	if (authenticated != 1)
		auth_clear_options();
done:
	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	free(pkalg);
	free(pkblob);
	return authenticated;
}

void
kexdh_server(Kex *kex)
{
	BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
	DH *dh;
	Key *server_host_key;
	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
	u_int sbloblen, klen, kout, hashlen;
	u_int slen;

	/* generate server DH public key */
	switch (kex->kex_type) {
	case KEX_DH_GRP1_SHA1:
		dh = dh_new_group1();
		break;
	case KEX_DH_GRP14_SHA1:
		dh = dh_new_group14();
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}
	dh_gen_key(dh, kex->we_need * 8);

	debug("expecting SSH2_MSG_KEXDH_INIT");
	packet_read_expect(SSH2_MSG_KEXDH_INIT);

	if (kex->load_host_key == NULL)
		fatal("Cannot load hostkey");
	server_host_key = kex->load_host_key(kex->hostkey_type);
	if (server_host_key == NULL)
		fatal("Unsupported hostkey type %d", kex->hostkey_type);

	/* key, cert */
	if ((dh_client_pub = BN_new()) == NULL)
		fatal("dh_client_pub == NULL");
	packet_get_bignum2(dh_client_pub);
	packet_check_eom();

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_client_pub= ");
	BN_print_fp(stderr, dh_client_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_client_pub));
#endif

#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif
	if (!dh_pub_is_valid(dh, dh_client_pub))
		packet_disconnect("bad client public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_client_pub, dh);
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexdh_server: BN_new failed");
	BN_bin2bn(kbuf, kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);

	/* calc H */
	kex_dh_hash(
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    server_host_key_blob, sbloblen,
	    dh_client_pub,
	    dh->pub_key,
	    shared_secret,
	    &hash, &hashlen
	);
	BN_clear_free(dh_client_pub);

	/* save session id := H */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	/* sign H */
	PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, hashlen));

	/* destroy_sensitive_data(); */

	/* send server hostkey, DH pubkey 'f' and singed H */
	packet_start(SSH2_MSG_KEXDH_REPLY);
	packet_put_string(server_host_key_blob, sbloblen);
	packet_put_bignum2(dh->pub_key);	/* f */
	packet_put_string(signature, slen);
	packet_send();
//.........这里部分代码省略.........

//.........这里部分代码省略.........
				 */
				/* Restore tty modes. */
				leave_raw_mode();

				/* Stop listening for new connections. */
				channel_stop_listening();

				snprintf(string, sizeof string,
				    "%c& [backgrounded]\n", escape_char);
				buffer_append(berr, string, strlen(string));

				/* Fork into background. */
				pid = fork();
				if (pid < 0) {
					error("fork: %.100s", strerror(errno));
					continue;
				}
				if (pid != 0) {	/* This is the parent. */
					/* The parent just exits. */
					exit(0);
				}
				/* The child continues serving connections. */
				if (compat20) {
					buffer_append(bin, "\004", 1);
					/* fake EOF on stdin */
					return -1;
				} else if (!stdin_eof) {
					/*
					 * Sending SSH_CMSG_EOF alone does not always appear
					 * to be enough.  So we try to send an EOF character
					 * first.
					 */
					packet_start(SSH_CMSG_STDIN_DATA);
					packet_put_string("\004", 1);
					packet_send();
					/* Close stdin. */
					stdin_eof = 1;
					if (buffer_len(bin) == 0) {
						packet_start(SSH_CMSG_EOF);
						packet_send();
					}
				}
				continue;

			case '?':
				snprintf(string, sizeof string,
"%c?\r\n\
Supported escape sequences:\r\n\
%c.  - terminate connection\r\n\
%cB  - send a BREAK to the remote system\r\n\
%cC  - open a command line\r\n\
%cR  - Request rekey (SSH protocol 2 only)\r\n\
%c^Z - suspend ssh\r\n\
%c#  - list forwarded connections\r\n\
%c&  - background ssh (when waiting for connections to terminate)\r\n\
%c?  - this message\r\n\
%c%c  - send the escape character by typing it twice\r\n\
(Note that escapes are only recognized immediately after newline.)\r\n",
				    escape_char, escape_char, escape_char, escape_char,
				    escape_char, escape_char, escape_char, escape_char,
				    escape_char, escape_char, escape_char);
				buffer_append(berr, string, strlen(string));
				continue;

			case '#':
				snprintf(string, sizeof string, "%c#\r\n", escape_char);

static int
try_krb4_authentication(void)
{
	KTEXT_ST auth;		/* Kerberos data */
	char *reply;
	char inst[INST_SZ];
	char *realm;
	CREDENTIALS cred;
	int r, type;
	socklen_t slen;
	Key_schedule schedule;
	u_long checksum, cksum;
	MSG_DAT msg_data;
	struct sockaddr_in local, foreign;
	struct stat st;

	/* Don't do anything if we don't have any tickets. */
	if (stat(tkt_string(), &st) < 0)
		return 0;

	strlcpy(inst, (char *)krb_get_phost(get_canonical_hostname(1)),
	    INST_SZ);

	realm = (char *)krb_realmofhost(get_canonical_hostname(1));
	if (!realm) {
		debug("Kerberos v4: no realm for %s", get_canonical_hostname(1));
		return 0;
	}
	/* This can really be anything. */
	checksum = (u_long)getpid();

	r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum);
	if (r != KSUCCESS) {
		debug("Kerberos v4 krb_mk_req failed: %s", krb_err_txt[r]);
		return 0;
	}
	/* Get session key to decrypt the server's reply with. */
	r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred);
	if (r != KSUCCESS) {
		debug("get_cred failed: %s", krb_err_txt[r]);
		return 0;
	}
	des_key_sched((des_cblock *) cred.session, schedule);

	/* Send authentication info to server. */
	packet_start(SSH_CMSG_AUTH_KERBEROS);
	packet_put_string((char *) auth.dat, auth.length);
	packet_send();
	packet_write_wait();

	/* Zero the buffer. */
	(void) memset(auth.dat, 0, MAX_KTXT_LEN);

	slen = sizeof(local);
	memset(&local, 0, sizeof(local));
	if (getsockname(packet_get_connection_in(),
	    (struct sockaddr *)&local, &slen) < 0)
		debug("getsockname failed: %s", strerror(errno));

	slen = sizeof(foreign);
	memset(&foreign, 0, sizeof(foreign));
	if (getpeername(packet_get_connection_in(),
	    (struct sockaddr *)&foreign, &slen) < 0) {
		debug("getpeername failed: %s", strerror(errno));
		cleanup_exit(255);
	}
	/* Get server reply. */
	type = packet_read();
	switch (type) {
	case SSH_SMSG_FAILURE:
		/* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */
		debug("Kerberos v4 authentication failed.");
		return 0;
		break;

	case SSH_SMSG_AUTH_KERBEROS_RESPONSE:
		/* SSH_SMSG_AUTH_KERBEROS_SUCCESS */
		debug("Kerberos v4 authentication accepted.");

		/* Get server's response. */
		reply = packet_get_string((u_int *) &auth.length);
		if (auth.length >= MAX_KTXT_LEN)
			fatal("Kerberos v4: Malformed response from server");
		memcpy(auth.dat, reply, auth.length);
		free(reply);

		packet_check_eom();

		/*
		 * If his response isn't properly encrypted with the session
		 * key, and the decrypted checksum fails to match, he's
		 * bogus. Bail out.
		 */
		r = krb_rd_priv(auth.dat, auth.length, (void *)schedule,
		    &cred.session, &foreign, &local, &msg_data);
		if (r != KSUCCESS) {
			debug("Kerberos v4 krb_rd_priv failed: %s",
			    krb_err_txt[r]);
			packet_disconnect("Kerberos v4 challenge failed!");
		}
//.........这里部分代码省略.........

void
kexgss_client(Kex *kex) {
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
	Gssctxt *ctxt;
	OM_uint32 maj_status, min_status, ret_flags;
	u_int klen, kout, slen = 0, hashlen, strlen;
	DH *dh; 
	BIGNUM *dh_server_pub = NULL;
	BIGNUM *shared_secret = NULL;
	BIGNUM *p = NULL;
	BIGNUM *g = NULL;	
	u_char *kbuf, *hash;
	u_char *serverhostkey = NULL;
	u_char *empty = "";
	char *msg;
	char *lang;
	int type = 0;
	int first = 1;
	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;

	/* Initialise our GSSAPI world */	
	ssh_gssapi_build_ctx(&ctxt);
	if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) 
	    == GSS_C_NO_OID)
		fatal("Couldn't identify host exchange");

	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
		fatal("Couldn't import hostname");

	if (kex->gss_client && 
	    ssh_gssapi_client_identity(ctxt, kex->gss_client))
		fatal("Couldn't acquire client credentials");

	switch (kex->kex_type) {
	case KEX_GSS_GRP1_SHA1:
		dh = dh_new_group1();
		break;
	case KEX_GSS_GRP14_SHA1:
		dh = dh_new_group14();
		break;
	case KEX_GSS_GEX_SHA1:
		debug("Doing group exchange\n");
		nbits = dh_estimate(kex->we_need * 8);
		packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
		packet_put_int(min);
		packet_put_int(nbits);
		packet_put_int(max);

		packet_send();

		packet_read_expect(SSH2_MSG_KEXGSS_GROUP);

		if ((p = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(p);
		if ((g = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(g);
		packet_check_eom();

		if (BN_num_bits(p) < min || BN_num_bits(p) > max)
			fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
			    min, BN_num_bits(p), max);

		dh = dh_new_group(g, p);
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}
	
	/* Step 1 - e is dh->pub_key */
	dh_gen_key(dh, kex->we_need * 8);

	/* This is f, we initialise it now to make life easier */
	dh_server_pub = BN_new();
	if (dh_server_pub == NULL)
		fatal("dh_server_pub == NULL");

	token_ptr = GSS_C_NO_BUFFER;
			 
	do {
		debug("Calling gss_init_sec_context");
		
		maj_status = ssh_gssapi_init_ctx(ctxt,
		    kex->gss_deleg_creds, token_ptr, &send_tok,
		    &ret_flags);

		if (GSS_ERROR(maj_status)) {
			if (send_tok.length != 0) {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
				    send_tok.length);
			}
			fatal("gss_init_context failed");
		}

		/* If we've got an old receive buffer get rid of it */
		if (token_ptr != GSS_C_NO_BUFFER)
			xfree(recv_tok.value);
//.........这里部分代码省略.........

/*
 * We only support those mechanisms that we know about (ie ones that we know
 * how to check local user kuserok and the like)
 */
static int
userauth_gssapi(Authctxt *authctxt)
{
	gss_OID_desc goid = {0, NULL};
	Gssctxt *ctxt = NULL;
	int mechs;
	int present;
	OM_uint32 ms;
	u_int len;
	u_char *doid = NULL;

	if (!authctxt->valid || authctxt->user == NULL)
		return (0);

	mechs = packet_get_int();
	if (mechs == 0) {
		debug("Mechanism negotiation is not supported");
		return (0);
	}

	do {
		mechs--;

		free(doid);

		present = 0;
		doid = packet_get_string(&len);

		if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
		    doid[1] == len - 2) {
			goid.elements = doid + 2;
			goid.length   = len - 2;
			ssh_gssapi_test_oid_supported(&ms, &goid, &present);
		} else {
			logit("Badly formed OID received");
		}
	} while (mechs > 0 && !present);

	if (!present) {
		free(doid);
		authctxt->server_caused_failure = 1;
		return (0);
	}

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
		if (ctxt != NULL)
			ssh_gssapi_delete_ctx(&ctxt);
		free(doid);
		authctxt->server_caused_failure = 1;
		return (0);
	}

	authctxt->methoddata = (void *)ctxt;

	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

	/* Return the OID that we received */
	packet_put_string(doid, len);

	packet_send();
	free(doid);

	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
	authctxt->postponed = 1;

	return (0);
}

//.........这里部分代码省略.........
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
			have_tty = 1;
		} else if (type == SSH_SMSG_FAILURE)
			logit("Warning: Remote host failed or refused to "
			    "allocate a pseudo tty.");
		else
			packet_disconnect("Protocol error waiting for pty "
			    "request response.");
	}
	/* Request X11 forwarding if enabled and DISPLAY is set. */
	display = getenv("DISPLAY");
	if (options.forward_x11 && display != NULL) {
		char *proto, *data;
		/* Get reasonable local authentication information. */
		client_x11_get_proto(display, options.xauth_location,
		    options.forward_x11_trusted, 
		    options.forward_x11_timeout,
		    &proto, &data);
		/* Request forwarding with authentication spoofing. */
		debug("Requesting X11 forwarding with authentication "
		    "spoofing.");
		x11_request_forwarding_with_spoofing(0, display, proto,
		    data, 0);
		/* Read response from the server. */
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
		} else if (type == SSH_SMSG_FAILURE) {
			logit("Warning: Remote host denied X11 forwarding.");
		} else {
			packet_disconnect("Protocol error waiting for X11 "
			    "forwarding");
		}
	}
	/* Tell the packet module whether this is an interactive session. */
	packet_set_interactive(interactive,
	    options.ip_qos_interactive, options.ip_qos_bulk);

	/* Request authentication agent forwarding if appropriate. */
	check_agent_present();

	if (options.forward_agent) {
		debug("Requesting authentication agent forwarding.");
		auth_request_forwarding();

		/* Read response from the server. */
		type = packet_read();
		packet_check_eom();
		if (type != SSH_SMSG_SUCCESS)
			logit("Warning: Remote host denied authentication agent forwarding.");
	}

	/* Initiate port forwardings. */
	ssh_init_stdio_forwarding();
	ssh_init_forwarding();

	/* Execute a local command */
	if (options.local_command != NULL &&
	    options.permit_local_command)
		ssh_local_cmd(options.local_command);

	/*
	 * If requested and we are not interested in replies to remote
	 * forwarding requests, then let ssh continue in the background.
	 */
	if (fork_after_authentication_flag) {
		if (options.exit_on_forward_failure &&
		    options.num_remote_forwards > 0) {
			debug("deferring postauth fork until remote forward "
			    "confirmation received");
		} else
			fork_postauth();
	}

	/*
	 * If a command was specified on the command line, execute the
	 * command now. Otherwise request the server to start a shell.
	 */
	if (buffer_len(&command) > 0) {
		int len = buffer_len(&command);
		if (len > 900)
			len = 900;
		debug("Sending command: %.*s", len,
		    (u_char *)buffer_ptr(&command));
		packet_start(SSH_CMSG_EXEC_CMD);
		packet_put_string(buffer_ptr(&command), buffer_len(&command));
		packet_send();
		packet_write_wait();
	} else {
		debug("Requesting shell.");
		packet_start(SSH_CMSG_EXEC_SHELL);
		packet_send();
		packet_write_wait();
	}

	/* Enter the interactive session. */
	return client_loop(have_tty, tty_flag ?
	    options.escape_char : SSH_ESCAPECHAR_NONE, 0);
}

void
input_gssapi_token(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok, recv_tok, g_mic_data;
	Buffer mic_data;
	OM_uint32 status;
	u_int slen;
	
	if (authctxt == NULL || authctxt->method == NULL)
		fatal("input_gssapi_response: no authentication context");
	gssctxt = authctxt->methoddata;
	
	recv_tok.value=packet_get_string(&slen);
	recv_tok.length=slen;	/* safe typecast */

	status=ssh_gssapi_init_ctx(gssctxt, authctxt->host,
					options.gss_deleg_creds,
					&recv_tok, &send_tok);

	packet_check_eom();
	
	if (GSS_ERROR(status)) {
		if (send_tok.length>0) {
			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
			packet_put_string(send_tok.value,send_tok.length);
			packet_send();
			packet_write_wait();
		}
		/* Start again with the next method in the list */
		clear_auth_state(authctxt);
		userauth(authctxt,NULL);
		return;
	}
	
	if (send_tok.length>0) {
		packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
		packet_put_string(send_tok.value,send_tok.length);
		packet_send();
		packet_write_wait();
	}

	if (status != GSS_S_COMPLETE)
		return;

	/* Make data buffer to MIC */
	buffer_init(&mic_data);
	buffer_put_string(&mic_data, session_id2, session_id2_len);
	buffer_put_char(&mic_data, SSH2_MSG_USERAUTH_REQUEST);
	buffer_put_cstring(&mic_data, authctxt->server_user);
	buffer_put_cstring(&mic_data, authctxt->service);
	buffer_put_cstring(&mic_data, authctxt->method->name);

	/* Make MIC */
	g_mic_data.value  = buffer_ptr(&mic_data);
	g_mic_data.length = buffer_len(&mic_data);

	status = ssh_gssapi_get_mic(gssctxt, &g_mic_data, &send_tok);
	buffer_clear(&mic_data);

	if (GSS_ERROR(status) || send_tok.length == 0) {
		/*
		 * Oops, now what?  There's no error token...
		 * Next userauth
		 */
		debug("GSS_GetMIC() failed! - "
		      "Abandoning GSSAPI userauth");
		clear_auth_state(authctxt);
		userauth(authctxt,NULL);
		return;
	}
	packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
	packet_put_string(send_tok.value,send_tok.length);
	packet_send();
	packet_write_wait();
}

//.........这里部分代码省略.........
			recv_tok.length = slen; 

			if ((dh_client_pub = BN_new()) == NULL)
				fatal("dh_client_pub == NULL");

			packet_get_bignum2(dh_client_pub);

			/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
			break;
		case SSH2_MSG_KEXGSS_CONTINUE:
			recv_tok.value = packet_get_string(&slen);
			recv_tok.length = slen; 
			break;
		default:
			packet_disconnect(
			    "Protocol error: didn't expect packet type %d",
			    type);
		}

		maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, 
		    &send_tok, &ret_flags));

		xfree(recv_tok.value);

		if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
			fatal("Zero length token output when incomplete");

		if (dh_client_pub == NULL)
			fatal("No client public key");
		
		if (maj_status & GSS_S_CONTINUE_NEEDED) {
			debug("Sending GSSAPI_CONTINUE");
			packet_start(SSH2_MSG_KEXGSS_CONTINUE);
			packet_put_string(send_tok.value, send_tok.length);
			packet_send();
			gss_release_buffer(&min_status, &send_tok);
		}
	} while (maj_status & GSS_S_CONTINUE_NEEDED);

	if (GSS_ERROR(maj_status)) {
		if (send_tok.length > 0) {
			packet_start(SSH2_MSG_KEXGSS_CONTINUE);
			packet_put_string(send_tok.value, send_tok.length);
			packet_send();
		}
		fatal("accept_ctx died");
	}

	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
		fatal("Mutual Authentication flag wasn't set");

	if (!(ret_flags & GSS_C_INTEG_FLAG))
		fatal("Integrity flag wasn't set");
	
	if (!dh_pub_is_valid(dh, dh_client_pub))
		packet_disconnect("bad client public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen); 
	kout = DH_compute_key(kbuf, dh_client_pub, dh);
	if (kout < 0)
		fatal("DH_compute_key: failed");

	shared_secret = BN_new();
	if (shared_secret == NULL)
		fatal("kexgss_server: BN_new failed");

void
input_gssapi_response(int type, u_int32_t plen, void *ctxt) 
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	OM_uint32 status,ms;
	u_int oidlen;
	char *oidv;
	gss_buffer_desc send_tok;
	
	if (authctxt == NULL)
		fatal("input_gssapi_response: no authentication context");
	gssctxt = authctxt->methoddata;
	
	/* Setup our OID */
	oidv=packet_get_string(&oidlen);
	
	if (datafellows & SSH_BUG_GSSAPI_BER) {
		if (!ssh_gssapi_check_mech_oid(gssctxt,oidv,oidlen)) {
			gss_OID oid;

			oid = ssh_gssapi_make_oid(oidlen, oidv);
			debug("Server returned different OID (%s) than expected (%s)",
				ssh_gssapi_oid_to_str(oid),
				ssh_gssapi_oid_to_str(gssctxt->desired_mech));
			ssh_gssapi_release_oid(&oid);
			clear_auth_state(authctxt);
			userauth(authctxt,NULL);
			return;
		}
	} else {
		if(oidv[0]!=0x06 || oidv[1]!=oidlen-2) {
			debug("Badly encoded mechanism OID received");
			clear_auth_state(authctxt);
			userauth(authctxt,NULL);
			return;
		}
		if (!ssh_gssapi_check_mech_oid(gssctxt,oidv+2,oidlen-2)) {
			gss_OID oid;

			oid = ssh_gssapi_make_oid(oidlen-2, oidv+2);
			debug("Server returned different OID (%s) than expected (%s)",
				ssh_gssapi_oid_to_str(oid),
				ssh_gssapi_oid_to_str(gssctxt->desired_mech));
			clear_auth_state(authctxt);
			userauth(authctxt,NULL);
			return;
		}
	}
		
	packet_check_eom();

        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN,&input_gssapi_token);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR,&input_gssapi_error);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK,&input_gssapi_errtok);
	
	status = ssh_gssapi_init_ctx(gssctxt, authctxt->host,
					options.gss_deleg_creds,
					GSS_C_NO_BUFFER, &send_tok);
	if (GSS_ERROR(status)) {
		if (send_tok.length>0) {
			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
			packet_put_string(send_tok.value,send_tok.length);
			packet_send();
			packet_write_wait();
		}
		/* Start again with next method on list */
		debug("Trying to start again");
		clear_auth_state(authctxt);
		userauth(authctxt,NULL);
		return;
	}

	/* We must have data to send */					
	packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
	packet_put_string(send_tok.value,send_tok.length);
	packet_send();
	packet_write_wait();
	gss_release_buffer(&ms, &send_tok);
}

int 
userauth_gssapi(Authctxt *authctxt)
{
	Gssctxt *gssctxt = NULL;
	static int initialized = 0;
	static int mech_idx = 0;
	static gss_OID_set supported = GSS_C_NULL_OID_SET;
	gss_OID mech = GSS_C_NULL_OID;

	/* Things work better if we send one mechanism at a time, rather
	 * than them all at once. This means that if we fail at some point
	 * in the middle of a negotiation, we can come back and try something
	 * different. */

	if (datafellows & SSH_OLD_GSSAPI) return 0;
	
	/* Before we offer a mechanism, check that we can support it. Don't
	 * bother trying to get credentials - as the standard fallback will
	 * deal with that kind of failure.
	 */

	if (!initialized) {
		initialized = 1;
		ssh_gssapi_client_mechs(authctxt->host, &supported);
		if (supported == GSS_C_NULL_OID_SET || supported->count == 0)
			return (0);
	} else if (supported != GSS_C_NULL_OID_SET) {
		/* Try next mech, if any */
		mech_idx++;

		if (mech_idx >= supported->count)
			return (0);
	} else {
		return (0);
	}

	mech = &supported->elements[mech_idx];

	ssh_gssapi_build_ctx(&gssctxt, 1, mech);
	authctxt->methoddata=(void *)gssctxt;
		
	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	packet_put_cstring(authctxt->server_user);
	packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
	
	packet_put_int(1);

	/* The newest gsskeyex draft stipulates that OIDs should
	 * be DER encoded, so we need to add the object type and
	 * length information back on */
	if (datafellows & SSH_BUG_GSSAPI_BER) {
		packet_put_string(mech->elements, mech->length);
	} else {
		packet_put_int((mech->length)+2);
		packet_put_char(0x06);
		packet_put_char(mech->length);
		packet_put_raw(mech->elements, mech->length);
	}

        packet_send();
        packet_write_wait();

        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE,&input_gssapi_response);

        return 1;
}

//.........这里部分代码省略.........
			    memcmp(prev_pkblob, pkblob, blen) != 0) {
				authctxt->method->abandons++;
				authctxt->method->attempts++;
			}
		}
		key_free(prev_key);
		authctxt->method->method_data = NULL;
	}

	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&b, authctxt->user);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		/* test for correct signature */
		if (user_key_allowed(authctxt->pw, key) &&
		    key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b)) == 1) {
			authenticated = 1;
		}
		authctxt->method->postponed = 0;
		buffer_free(&b);
		xfree(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		if (user_key_allowed(authctxt->pw, key)) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->method->postponed = 1;
			/*
			 * Remember key that was tried so we can
			 * correctly detect abandonment.  See above.
			 */
			authctxt->method->method_data = (void *) key;
			key = NULL;
		}
	}
	if (authenticated != 1)
		auth_clear_options();

done:
	/*
	 * XXX TODO: add config options for specifying users for whom
	 * this userauth is insufficient and what userauths may
	 * continue.
	 */
#ifdef USE_PAM
	if (authenticated) {
		if (!do_pam_non_initial_userauth(authctxt))
			authenticated = 0;
	}
#endif /* USE_PAM */

	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
#ifdef HAVE_CYGWIN
	if (check_nt_auth(0, authctxt->pw) == 0)
		return;
#endif
	if (authenticated)
		authctxt->method->authenticated = 1;
}

/*
 * Encodes terminal modes for the terminal referenced by fd
 * or tiop in a portable manner, and appends the modes to a packet
 * being constructed.
 */
void
tty_make_modes(int fd, struct termios *tiop)
{
	struct termios tio;
	int baud;
	Buffer buf;
	int tty_op_ospeed, tty_op_ispeed;
	void (*put_arg)(Buffer *, u_int);

	buffer_init(&buf);
	if (compat20) {
		tty_op_ospeed = TTY_OP_OSPEED_PROTO2;
		tty_op_ispeed = TTY_OP_ISPEED_PROTO2;
		put_arg = buffer_put_int;
	} else {
		tty_op_ospeed = TTY_OP_OSPEED_PROTO1;
		tty_op_ispeed = TTY_OP_ISPEED_PROTO1;
		put_arg = (void (*)(Buffer *, u_int)) buffer_put_char;
	}

	if (tiop == NULL) {
		if (fd == -1) {
			debug("tty_make_modes: no fd or tio");
			goto end;
		}
		if (tcgetattr(fd, &tio) == -1) {
			logit("tcgetattr: %.100s", strerror(errno));
			goto end;
		}
	} else
		tio = *tiop;

	/* Store input and output baud rates. */
	baud = speed_to_baud(cfgetospeed(&tio));
	buffer_put_char(&buf, tty_op_ospeed);
	buffer_put_int(&buf, baud);
	baud = speed_to_baud(cfgetispeed(&tio));
	buffer_put_char(&buf, tty_op_ispeed);
	buffer_put_int(&buf, baud);

	/* Store values of mode flags. */
#define TTYCHAR(NAME, OP) \
	buffer_put_char(&buf, OP); \
	put_arg(&buf, special_char_encode(tio.c_cc[NAME]));

#define TTYMODE(NAME, FIELD, OP) \
	buffer_put_char(&buf, OP); \
	put_arg(&buf, ((tio.FIELD & NAME) != 0));

#include "ttymodes.h"

#undef TTYCHAR
#undef TTYMODE

end:
	/* Mark end of mode data. */
	buffer_put_char(&buf, TTY_OP_END);
	if (compat20)
		packet_put_string(buffer_ptr(&buf), buffer_len(&buf));
	else
		packet_put_raw(buffer_ptr(&buf), buffer_len(&buf));
	buffer_free(&buf);
}