/**
 * @brief Blocking write on channel.
 *
 * @param channel       The channel to write to.
 *
 * @param data          A pointer to the data to write.
 *
 * @param len           The length of the buffer to write to.
 *
 * @return The number of bytes written, SSH_ERROR on error.
 *
 * @see channel_read()
 */
int channel_write(CHANNEL *channel, const void *data, u32 len) {
  SSH_SESSION *session = channel->session;
  int origlen = len;
  int effectivelen;

  enter_function();

  if (channel->local_eof) {
    ssh_set_error(session, SSH_REQUEST_DENIED,
        "Can't write to channel %d:%d  after EOF was sent",
        channel->local_channel,
        channel->remote_channel);
    leave_function();
    return -1;
  }

  if (channel->open == 0 || channel->delayed_close != 0) {
    ssh_set_error(session, SSH_REQUEST_DENIED, "Remote channel is closed");
    leave_function();
    return -1;
  }

#ifdef HAVE_SSH1
  if (channel->version == 1) {
    int rc = channel_write1(channel, data, len);
    leave_function();
    return rc;
  }
#endif

  while (len > 0) {
    if (channel->remote_window < len) {
      ssh_log(session, SSH_LOG_PROTOCOL,
          "Remote window is %d bytes. going to write %d bytes",
          channel->remote_window,
          len);
      ssh_log(session, SSH_LOG_PROTOCOL,
          "Waiting for a growing window message...");
      /* What happens when the channel window is zero? */
      while(channel->remote_window == 0) {
        /* parse every incoming packet */
        packet_wait(channel->session, 0, 0);
      }
      effectivelen = len > channel->remote_window ? channel->remote_window : len;
    } else {
      effectivelen = len;
    }

    if (buffer_add_u8(session->out_buffer, SSH2_MSG_CHANNEL_DATA) < 0 ||
        buffer_add_u32(session->out_buffer,
          htonl(channel->remote_channel)) < 0 ||
        buffer_add_u32(session->out_buffer, htonl(effectivelen)) < 0 ||
        buffer_add_data(session->out_buffer, data, effectivelen) < 0) {
      goto error;
    }

    if (packet_send(session) != SSH_OK) {
      leave_function();
      return SSH_ERROR;
    }

    ssh_log(session, SSH_LOG_RARE,
        "channel_write wrote %d bytes", effectivelen);

    channel->remote_window -= effectivelen;
    len -= effectivelen;
    data += effectivelen;
  }

  leave_function();
  return origlen;
error:
  buffer_free(session->out_buffer);

  leave_function();
  return SSH_ERROR;
}

/*
 * Performs authentication of an incoming connection.  Session key has already
 * been exchanged and encryption is enabled.
 */
void
do_authentication(Authctxt *authctxt)
{
	u_int ulen;
	char *user, *style = NULL;

	/* Get the name of the user that we wish to log in as. */
	packet_read_expect(SSH_CMSG_USER);

	/* Get the user name. */
	user = packet_get_cstring(&ulen);
	packet_check_eom();

	if ((style = strchr(user, ':')) != NULL)
		*style++ = '\0';

#ifdef KRB5
	/* XXX - SSH.com Kerberos v5 braindeath. */
	if ((datafellows & SSH_BUG_K5USER) &&
	    options.kerberos_authentication) {
		char *p;
		if ((p = strchr(user, '@')) != NULL)
			*p = '\0';
	}
#endif

	authctxt->user = user;
	authctxt->style = style;

	/* Verify that the user is a valid user. */
	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
		authctxt->valid = 1;
	else {
		debug("do_authentication: invalid user %s", user);
		authctxt->pw = fakepw();
	}

	/* Configuration may have changed as a result of Match */
	if (options.num_auth_methods != 0)
		fatal("AuthenticationMethods is not supported with SSH "
		    "protocol 1");

	setproctitle("%s%s", authctxt->valid ? user : "unknown",
	    use_privsep ? " [net]" : "");

#ifdef USE_PAM
	if (options.use_pam)
		PRIVSEP(start_pam(authctxt));
#endif

	/*
	 * If we are not running as root, the user must have the same uid as
	 * the server.
	 */
	if (!use_privsep && getuid() != 0 && authctxt->pw &&
	    authctxt->pw->pw_uid != getuid())
		packet_disconnect("Cannot change user when server not running as root.");

	/*
	 * Loop until the user has been authenticated or the connection is
	 * closed, do_authloop() returns only if authentication is successful
	 */
	do_authloop(authctxt);

	/* The user has been authenticated and accepted. */
	packet_start(SSH_SMSG_SUCCESS);
	packet_send();
	packet_write_wait();
}

static int dh_handshake_server(ssh_session session) {
  ssh_key privkey;
  ssh_string sig_blob;
  ssh_string f;
  int rc;

  if (dh_generate_y(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not create y number");
    return -1;
  }
  if (dh_generate_f(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not create f number");
    return -1;
  }

  f = dh_get_f(session);
  if (f == NULL) {
    ssh_set_error(session, SSH_FATAL, "Could not get the f number");
    return -1;
  }

  if (ssh_get_key_params(session,&privkey) != SSH_OK){
      ssh_string_free(f);
      return -1;
  }

  if (dh_build_k(session) < 0) {
    ssh_set_error(session, SSH_FATAL, "Could not import the public key");
    ssh_string_free(f);
    return -1;
  }

  if (make_sessionid(session) != SSH_OK) {
    ssh_set_error(session, SSH_FATAL, "Could not create a session id");
    ssh_string_free(f);
    return -1;
  }

  sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey);
  if (sig_blob == NULL) {
    ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
    ssh_string_free(f);
    return -1;
  }

  rc = ssh_buffer_pack(session->out_buffer,
                       "bSSS",
                       SSH2_MSG_KEXDH_REPLY,
                       session->next_crypto->server_pubkey,
                       f,
                       sig_blob);
  ssh_string_free(f);
  ssh_string_free(sig_blob);
  if(rc != SSH_OK){
    ssh_set_error_oom(session);
    ssh_buffer_reinit(session->out_buffer);
    return -1;
  }

  if (packet_send(session) == SSH_ERROR) {
    return -1;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
    ssh_buffer_reinit(session->out_buffer);
    return -1;
  }

  if (packet_send(session) == SSH_ERROR) {
    return -1;
  }
  SSH_LOG(SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
  session->dh_handshake_state=DH_STATE_NEWKEYS_SENT;

  return 0;
}

static int
roaming_resume(void)
{
	u_int64_t recv_bytes;
	char *str = NULL, *kexlist = NULL, *c;
	int i, type;
	int timeout_ms = options.connection_timeout * 1000;
	u_int len;
	u_int32_t rnd = 0;

	resume_in_progress = 1;

	/* Exchange banners */
	ssh_exchange_identification(timeout_ms);
	packet_set_nonblocking();

	/* Send a kexinit message with [email protected] as only kex algo */
	packet_start(SSH2_MSG_KEXINIT);
	for (i = 0; i < KEX_COOKIE_LEN; i++) {
		if (i % 4 == 0)
			rnd = arc4random();
		packet_put_char(rnd & 0xff);
		rnd >>= 8;
	}
	packet_put_cstring(KEX_RESUME);
	for (i = 1; i < PROPOSAL_MAX; i++) {
		/* kex algorithm added so start with i=1 and not 0 */
		packet_put_cstring(""); /* Not used when we resume */
	}
	packet_put_char(1); /* first kex_packet follows */
	packet_put_int(0); /* reserved */
	packet_send();

	/* Assume that [email protected] will be accepted */
	packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
	packet_put_int(roaming_id);
	packet_send();

	/* Read the server's kexinit and check for [email protected] */
	if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
		debug("expected kexinit on resume, got %d", type);
		goto fail;
	}
	for (i = 0; i < KEX_COOKIE_LEN; i++)
		(void)packet_get_char();
	kexlist = packet_get_string(&len);
	if (!kexlist
	    || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
		debug("server doesn't allow resume");
		goto fail;
	}
	free(str);
	for (i = 1; i < PROPOSAL_MAX; i++) {
		/* kex algorithm taken care of so start with i=1 and not 0 */
		free(packet_get_string(&len));
	}
	i = packet_get_char(); /* first_kex_packet_follows */
	if (i && (c = strchr(kexlist, ',')))
		*c = 0;
	if (i && strcmp(kexlist, KEX_RESUME)) {
		debug("server's kex guess (%s) was wrong, skipping", kexlist);
		(void)packet_read(); /* Wrong guess - discard packet */
	}

	/*
	 * Read the ROAMING_AUTH_REQUIRED challenge from the server and
	 * send ROAMING_AUTH
	 */
	if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
		debug("expected roaming_auth_required, got %d", type);
		goto fail;
	}
	roaming_auth_required();

	/* Read ROAMING_AUTH_OK from the server */
	if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
		debug("expected roaming_auth_ok, got %d", type);
		goto fail;
	}
	recv_bytes = packet_get_int64() ^ oldkey2;
	debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
	resend_bytes(packet_get_connection_out(), &recv_bytes);

	resume_in_progress = 0;

	session_resumed = 1; /* Tell clientloop */

	return 0;

fail:
	free(kexlist);
	if (packet_get_connection_in() == packet_get_connection_out())
		close(packet_get_connection_in());
	else {
		close(packet_get_connection_in());
		close(packet_get_connection_out());
	}
	return 1;
}

static int
userauth_pubkey(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_pubkey: disabled because of invalid user");
		return 0;
	}
	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		logit("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		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);
		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 */
		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;
		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 (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;
//.........这里部分代码省略.........

void
kexgss_server(Kex *kex)
{
	OM_uint32 maj_status, min_status;
	
	/* 
	 * Some GSSAPI implementations use the input value of ret_flags (an
 	 * output variable) as a means of triggering mechanism specific 
 	 * features. Initializing it to zero avoids inadvertently 
 	 * activating this non-standard behaviour.
	 */

	OM_uint32 ret_flags = 0;
	gss_buffer_desc gssbuf, recv_tok, msg_tok;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	Gssctxt *ctxt = NULL;
	u_int slen, klen, kout, hashlen;
	u_char *kbuf, *hash;
	DH *dh;
	int min = -1, max = -1, nbits = -1;
	BIGNUM *shared_secret = NULL;
	BIGNUM *dh_client_pub = NULL;
	int type = 0;
	gss_OID oid;
	char *mechs;

	/* Initialise GSSAPI */

	/* If we're rekeying, privsep means that some of the private structures
	 * in the GSSAPI code are no longer available. This kludges them back
	 * into life
	 */
	if (!ssh_gssapi_oid_table_ok()) 
		if ((mechs = ssh_gssapi_server_mechanisms()))
			xfree(mechs);

	debug2("%s: Identifying %s", __func__, kex->name);
	oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
	if (oid == GSS_C_NO_OID)
	   fatal("Unknown gssapi mechanism");

	debug2("%s: Acquiring credentials", __func__);

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
		fatal("Unable to acquire credentials for the server");

	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");
		packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
		min = packet_get_int();
		nbits = packet_get_int();
		max = packet_get_int();
		min = MAX(DH_GRP_MIN, min);
		max = MIN(DH_GRP_MAX, max);
		packet_check_eom();
		if (max < min || nbits < min || max < nbits)
			fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
			    min, nbits, max);
		dh = PRIVSEP(choose_dh(min, nbits, max));
		if (dh == NULL)
			packet_disconnect("Protocol error: no matching group found");

		packet_start(SSH2_MSG_KEXGSS_GROUP);
		packet_put_bignum2(dh->p);
		packet_put_bignum2(dh->g);
		packet_send();

		packet_write_wait();
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}

	dh_gen_key(dh, kex->we_need * 8);

	do {
		debug("Wait SSH2_MSG_GSSAPI_INIT");
		type = packet_read();
		switch(type) {
		case SSH2_MSG_KEXGSS_INIT:
			if (dh_client_pub != NULL) 
				fatal("Received KEXGSS_INIT after initialising");
			recv_tok.value = packet_get_string(&slen);
			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:
//.........这里部分代码省略.........

/**
 * @brief Disconnect from a session (client or server).
 * The session can then be reused to open a new session.
 *
 * @param[in]  session  The SSH session to use.
 */
void ssh_disconnect(ssh_session session) {
  ssh_string str = NULL;
  struct ssh_iterator *it;

  if (session == NULL) {
    return;
  }

  enter_function();

  if (ssh_socket_is_open(session->socket)) {
    if (buffer_add_u8(session->out_buffer, SSH2_MSG_DISCONNECT) < 0) {
      goto error;
    }
    if (buffer_add_u32(session->out_buffer,
          htonl(SSH2_DISCONNECT_BY_APPLICATION)) < 0) {
      goto error;
    }

    str = ssh_string_from_char("Bye Bye");
    if (str == NULL) {
      goto error;
    }

    if (buffer_add_ssh_string(session->out_buffer,str) < 0) {
      ssh_string_free(str);
      goto error;
    }
    ssh_string_free(str);

    packet_send(session);
    ssh_socket_close(session->socket);
  }
error:
  session->alive = 0;
  if(session->socket){
    ssh_socket_reset(session->socket);
  }
  session->opts.fd = SSH_INVALID_SOCKET;
  session->session_state=SSH_SESSION_STATE_DISCONNECTED;

  while ((it=ssh_list_get_iterator(session->channels)) != NULL) {
    ssh_channel_free(ssh_iterator_value(ssh_channel,it));
    ssh_list_remove(session->channels, it);
  }
  if(session->current_crypto){
    crypto_free(session->current_crypto);
    session->current_crypto=NULL;
  }
  if(session->in_buffer)
    buffer_reinit(session->in_buffer);
  if(session->out_buffer)
    buffer_reinit(session->out_buffer);
  if(session->in_hashbuf)
    buffer_reinit(session->in_hashbuf);
  if(session->out_hashbuf)
    buffer_reinit(session->out_hashbuf);
  session->auth_methods = 0;
  SAFE_FREE(session->serverbanner);
  SAFE_FREE(session->clientbanner);

  if(session->ssh_message_list){
    ssh_message msg;
    while((msg=ssh_list_pop_head(ssh_message ,session->ssh_message_list))
        != NULL){
      ssh_message_free(msg);
    }
    ssh_list_free(session->ssh_message_list);
    session->ssh_message_list=NULL;
  }

  if (session->packet_callbacks){
    ssh_list_free(session->packet_callbacks);
    session->packet_callbacks=NULL;
  }

  leave_function();
}

/** @internal
 * replies to an SSH_AUTH packet with a default (denied) response.
 */
int ssh_auth_reply_default(ssh_session session,int partial) {
  char methods_c[128] = {0};
  ssh_string methods = NULL;
  int rc = SSH_ERROR;

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_FAILURE) < 0) {
    return rc;
  }

  if (session->auth_methods == 0) {
    session->auth_methods = SSH_AUTH_METHOD_PUBLICKEY | SSH_AUTH_METHOD_PASSWORD;
  }
  if (session->auth_methods & SSH_AUTH_METHOD_PUBLICKEY) {
    strncat(methods_c, "publickey,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC){
	  strncat(methods_c,"gssapi-with-mic,",
			  sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth_methods & SSH_AUTH_METHOD_INTERACTIVE) {
    strncat(methods_c, "keyboard-interactive,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth_methods & SSH_AUTH_METHOD_PASSWORD) {
    strncat(methods_c, "password,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }
  if (session->auth_methods & SSH_AUTH_METHOD_HOSTBASED) {
    strncat(methods_c, "hostbased,",
            sizeof(methods_c) - strlen(methods_c) - 1);
  }

  if (methods_c[0] == '\0' || methods_c[strlen(methods_c)-1] != ',') {
      return SSH_ERROR;
  }

  /* Strip the comma. */
  methods_c[strlen(methods_c) - 1] = '\0'; // strip the comma. We are sure there is at

  SSH_LOG(SSH_LOG_PACKET,
      "Sending a auth failure. methods that can continue: %s", methods_c);

  methods = ssh_string_from_char(methods_c);
  if (methods == NULL) {
    goto error;
  }

  if (buffer_add_ssh_string(session->out_buffer, methods) < 0) {
    goto error;
  }

  if (partial) {
    if (buffer_add_u8(session->out_buffer, 1) < 0) {
      goto error;
    }
  } else {
    if (buffer_add_u8(session->out_buffer, 0) < 0) {
      goto error;
    }
  }

  rc = packet_send(session);
error:
  ssh_string_free(methods);

  return rc;
}

int ssh_message_auth_interactive_request(ssh_message msg, const char *name,
                            const char *instruction, unsigned int num_prompts,
                            const char **prompts, char *echo) {
  int r;
  unsigned int i = 0;
  ssh_string tmp = NULL;

  if(name == NULL || instruction == NULL) {
    return SSH_ERROR;
  }
  if(num_prompts > 0 && (prompts == NULL || echo == NULL)) {
    return SSH_ERROR;
  }

  if (buffer_add_u8(msg->session->out_buffer, SSH2_MSG_USERAUTH_INFO_REQUEST) < 0) {
    return SSH_ERROR;
  }

  /* name */
  tmp = ssh_string_from_char(name);
  if (tmp == NULL) {
      return SSH_ERROR;
  }

  r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
  ssh_string_free(tmp);
  if (r < 0) {
    return SSH_ERROR;
  }

  /* instruction */
  tmp = ssh_string_from_char(instruction);
  if (tmp == NULL) {
      return SSH_ERROR;
  }

  r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
  ssh_string_free(tmp);
  if (r < 0) {
    return SSH_ERROR;
  }

  /* language tag */
  tmp = ssh_string_from_char("");
  if (tmp == NULL) {
      return SSH_ERROR;
  }

  r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
  ssh_string_free(tmp);
  if (r < 0) {
    return SSH_ERROR;
  }

  /* num prompts */
  if (buffer_add_u32(msg->session->out_buffer, ntohl(num_prompts)) < 0) {
    return SSH_ERROR;
  }

  for(i = 0; i < num_prompts; i++) {
    /* prompt[i] */
    tmp = ssh_string_from_char(prompts[i]);
    if (tmp == NULL) {
        return SSH_ERROR;
    }

    r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
    ssh_string_free(tmp);
    if (r < 0) {
        return SSH_ERROR;
    }

    /* echo[i] */
    if (buffer_add_u8(msg->session->out_buffer, echo[i]) < 0) {
        return SSH_ERROR;
    }
  }

  r = packet_send(msg->session);

  /* fill in the kbdint structure */
  if (msg->session->kbdint == NULL) {
    SSH_LOG(SSH_LOG_PROTOCOL, "Warning: Got a "
                                        "keyboard-interactive response but it "
                                        "seems we didn't send the request.");

    msg->session->kbdint = ssh_kbdint_new();
    if (msg->session->kbdint == NULL) {
      ssh_set_error_oom(msg->session);

      return SSH_ERROR;
    }
  } else {
    ssh_kbdint_clean(msg->session->kbdint);
  }

  msg->session->kbdint->name = strdup(name);
  if(msg->session->kbdint->name == NULL) {
      ssh_set_error_oom(msg->session);
      ssh_kbdint_free(msg->session->kbdint);
//.........这里部分代码省略.........

static int
server_input_global_request(int type, u_int32_t seq, void *ctxt)
{
	char *rtype;
	int want_reply;
	int r, success = 0, allocated_listen_port = 0;
	struct sshbuf *resp = NULL;

	rtype = packet_get_string(NULL);
	want_reply = packet_get_char();
	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);

	/* -R style forwarding */
	if (strcmp(rtype, "tcpip-forward") == 0) {
		struct passwd *pw;
		struct Forward fwd;

		pw = the_authctxt->pw;
		if (pw == NULL || !the_authctxt->valid)
			fatal("server_input_global_request: no/invalid user");
		memset(&fwd, 0, sizeof(fwd));
		fwd.listen_host = packet_get_string(NULL);
		fwd.listen_port = (u_short)packet_get_int();
		debug("server_input_global_request: tcpip-forward listen %s port %d",
		    fwd.listen_host, fwd.listen_port);

		/* check permissions */
		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
		    no_port_forwarding_flag ||
		    (!want_reply && fwd.listen_port == 0)
#ifndef NO_IPPORT_RESERVED_CONCEPT
		    || (fwd.listen_port != 0 && fwd.listen_port < IPPORT_RESERVED &&
		    pw->pw_uid != 0)
#endif
		    ) {
			success = 0;
			packet_send_debug("Server has disabled port forwarding.");
		} else {
			/* Start listening on the port */
			success = channel_setup_remote_fwd_listener(&fwd,
			    &allocated_listen_port, &options.fwd_opts);
		}
		free(fwd.listen_host);
		if ((resp = sshbuf_new()) == NULL)
			fatal("%s: sshbuf_new", __func__);
		if ((r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
			fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
		struct Forward fwd;

		memset(&fwd, 0, sizeof(fwd));
		fwd.listen_host = packet_get_string(NULL);
		fwd.listen_port = (u_short)packet_get_int();
		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
		    fwd.listen_host, fwd.listen_port);

		success = channel_cancel_rport_listener(&fwd);
		free(fwd.listen_host);
	} else if (strcmp(rtype, "[email protected]") == 0) {
		struct Forward fwd;

		memset(&fwd, 0, sizeof(fwd));
		fwd.listen_path = packet_get_string(NULL);
		debug("server_input_global_request: streamlocal-forward listen path %s",
		    fwd.listen_path);

		/* check permissions */
		if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0
		    || no_port_forwarding_flag) {
			success = 0;
			packet_send_debug("Server has disabled port forwarding.");
		} else {
			/* Start listening on the socket */
			success = channel_setup_remote_fwd_listener(
			    &fwd, NULL, &options.fwd_opts);
		}
		free(fwd.listen_path);
	} else if (strcmp(rtype, "[email protected]") == 0) {
		struct Forward fwd;

		memset(&fwd, 0, sizeof(fwd));
		fwd.listen_path = packet_get_string(NULL);
		debug("%s: cancel-streamlocal-forward path %s", __func__,
		    fwd.listen_path);

		success = channel_cancel_rport_listener(&fwd);
		free(fwd.listen_path);
	} else if (strcmp(rtype, "[email protected]") == 0) {
		no_more_sessions = 1;
		success = 1;
	} else if (strcmp(rtype, "[email protected]") == 0) {
		success = server_input_hostkeys_prove(&resp);
	}
	if (want_reply) {
		packet_start(success ?
		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
		if (success && resp != NULL)
			ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
			    sshbuf_len(resp));
		packet_send();
//.........这里部分代码省略.........

/* process the characters one by one */
static int
process_escapes(Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len)
{
	char string[1024];
	pid_t pid;
	int bytes = 0;
	u_int i;
	u_char ch;
	char *s;

	for (i = 0; i < len; i++) {
		/* Get one character at a time. */
		ch = buf[i];

		if (escape_pending) {
			/* We have previously seen an escape character. */
			/* Clear the flag now. */
			escape_pending = 0;

			/* Process the escaped character. */
			switch (ch) {
			case '.':
				/* Terminate the connection. */
				snprintf(string, sizeof string, "%c.\r\n", escape_char);
				buffer_append(berr, string, strlen(string));

				quit_pending = 1;
				return -1;

			case 'Z' - 64:
				/* Suspend the program. */
				/* Print a message to that effect to the user. */
				snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", escape_char);
				buffer_append(berr, string, strlen(string));

				/* Restore terminal modes and suspend. */
				client_suspend_self(bin, bout, berr);

				/* We have been continued. */
				continue;

			case 'B':
				if (compat20) {
					snprintf(string, sizeof string,
					    "%cB\r\n", escape_char);
					buffer_append(berr, string,
					    strlen(string));
					channel_request_start(session_ident,
					    "break", 0);
					packet_put_int(1000);
					packet_send();
				}
				continue;

			case 'R':
				if (compat20) {
					if (datafellows & SSH_BUG_NOREKEY)
						logit("Server does not support re-keying");
					else
						need_rekeying = 1;
				}
				continue;

			case '&':
				/*
				 * Detach the program (continue to serve connections,
				 * but put in background and no more new connections).
				 */
				/* 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.
					 */
//.........这里部分代码省略.........

/*
 * Checks if the user has an authentication agent, and if so, tries to
 * authenticate using the agent.
 */
static int
try_agent_authentication(void)
{
	int type;
	char *comment;
	AuthenticationConnection *auth;
	u_char response[16];
	u_int i;
	Key *key;
	BIGNUM *challenge;

	/* Get connection to the agent. */
	auth = ssh_get_authentication_connection();
	if (!auth)
		return 0;

	if ((challenge = BN_new()) == NULL)
		fatal("try_agent_authentication: BN_new failed");
	/* Loop through identities served by the agent. */
	for (key = ssh_get_first_identity(auth, &comment, 1);
	    key != NULL;
	    key = ssh_get_next_identity(auth, &comment, 1)) {

		/* Try this identity. */
		debug("Trying RSA authentication via agent with '%.100s'", comment);
		free(comment);

		/* Tell the server that we are willing to authenticate using this key. */
		packet_start(SSH_CMSG_AUTH_RSA);
		packet_put_bignum(key->rsa->n);
		packet_send();
		packet_write_wait();

		/* Wait for server's response. */
		type = packet_read();

		/* The server sends failure if it doesn't like our key or
		   does not support RSA authentication. */
		if (type == SSH_SMSG_FAILURE) {
			debug("Server refused our key.");
			key_free(key);
			continue;
		}
		/* Otherwise it should have sent a challenge. */
		if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
			packet_disconnect("Protocol error during RSA authentication: %d",
					  type);

		packet_get_bignum(challenge);
		packet_check_eom();

		debug("Received RSA challenge from server.");

		/* Ask the agent to decrypt the challenge. */
		if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) {
			/*
			 * The agent failed to authenticate this identifier
			 * although it advertised it supports this.  Just
			 * return a wrong value.
			 */
			logit("Authentication agent failed to decrypt challenge.");
			explicit_bzero(response, sizeof(response));
		}
		key_free(key);
		debug("Sending response to RSA challenge.");

		/* Send the decrypted challenge back to the server. */
		packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
		for (i = 0; i < 16; i++)
			packet_put_char(response[i]);
		packet_send();
		packet_write_wait();

		/* Wait for response from the server. */
		type = packet_read();

		/* The server returns success if it accepted the authentication. */
		if (type == SSH_SMSG_SUCCESS) {
			ssh_close_authentication_connection(auth);
			BN_clear_free(challenge);
			debug("RSA authentication accepted by server.");
			return 1;
		}
		/* Otherwise it should return failure. */
		if (type != SSH_SMSG_FAILURE)
			packet_disconnect("Protocol error waiting RSA auth response: %d",
					  type);
	}
	ssh_close_authentication_connection(auth);
	BN_clear_free(challenge);
	debug("RSA authentication using agent refused.");
	return 0;
}

static void
server_input_global_request(int type, u_int32_t seq, void *ctxt)
{
	char *rtype;
	int want_reply;
	int success = 0, allocated_listen_port = 0;

	rtype = packet_get_string(NULL);
	want_reply = packet_get_char();
	debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);

	/* -R style forwarding */
	if (strcmp(rtype, "tcpip-forward") == 0) {
		struct passwd *pw;
		char *listen_address;
		u_short listen_port;

		pw = the_authctxt->pw;
		if (pw == NULL || !the_authctxt->valid)
			fatal("server_input_global_request: no/invalid user");
		listen_address = packet_get_string(NULL);
		listen_port = (u_short)packet_get_int();
		debug("server_input_global_request: tcpip-forward listen %s port %d",
		    listen_address, listen_port);

		/* check permissions */
		if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 ||
		    no_port_forwarding_flag ||
		    (!want_reply && listen_port == 0)
#ifndef NO_IPPORT_RESERVED_CONCEPT
		    || (listen_port != 0 && listen_port < IPPORT_RESERVED &&
                    pw->pw_uid != 0)
#endif
		    ) {
			success = 0;
			packet_send_debug("Server has disabled port forwarding.");
		} else {
			/* Start listening on the port */
			success = channel_setup_remote_fwd_listener(
			    listen_address, listen_port,
			    &allocated_listen_port, options.gateway_ports);
		}
		xfree(listen_address);
	} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
		char *cancel_address;
		u_short cancel_port;

		cancel_address = packet_get_string(NULL);
		cancel_port = (u_short)packet_get_int();
		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
		    cancel_address, cancel_port);

		success = channel_cancel_rport_listener(cancel_address,
		    cancel_port);
		xfree(cancel_address);
	} else if (strcmp(rtype, "[email protected]") == 0) {
		no_more_sessions = 1;
		success = 1;
	}
	if (want_reply) {
		packet_start(success ?
		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
		if (success && allocated_listen_port > 0)
			packet_put_int(allocated_listen_port);
		packet_send();
		packet_write_wait();
	}
	xfree(rtype);
}

static int channel_request(CHANNEL *channel, const char *request,
    BUFFER *buffer, int reply) {
  SSH_SESSION *session = channel->session;
  STRING *req = NULL;
  int rc = SSH_ERROR;

  enter_function();

  req = string_from_char(request);
  if (req == NULL) {
    goto error;
  }

  if (buffer_add_u8(session->out_buffer, SSH2_MSG_CHANNEL_REQUEST) < 0 ||
      buffer_add_u32(session->out_buffer, htonl(channel->remote_channel)) < 0 ||
      buffer_add_ssh_string(session->out_buffer, req) < 0 ||
      buffer_add_u8(session->out_buffer, reply == 0 ? 0 : 1) < 0) {
    goto error;
  }
  string_free(req);

  if (buffer != NULL) {
    if (buffer_add_data(session->out_buffer, buffer_get(buffer),
        buffer_get_len(buffer)) < 0) {
      goto error;
    }
  }

  if (packet_send(session) != SSH_OK) {
    leave_function();
    return rc;
  }

  ssh_log(session, SSH_LOG_RARE,
      "Sent a SSH_MSG_CHANNEL_REQUEST %s", request);
  if (reply == 0) {
    leave_function();
    return SSH_OK;
  }

  rc = packet_wait(session, SSH2_MSG_CHANNEL_SUCCESS, 1);
  if (rc) {
    if (session->in_packet.type == SSH2_MSG_CHANNEL_FAILURE) {
      ssh_log(session, SSH_LOG_PACKET,
          "%s channel request failed", request);
      ssh_set_error(session, SSH_REQUEST_DENIED,
          "Channel request %s failed", request);
    } else {
      ssh_log(session, SSH_LOG_RARE,
          "Received an unexpected %d message", session->in_packet.type);
    }
  } else {
    ssh_log(session, SSH_LOG_RARE, "Received a SUCCESS");
  }

  leave_function();
  return rc;
error:
  buffer_free(session->out_buffer);
  string_free(req);

  leave_function();
  return rc;
}

/*
 * 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);
}

/*
 * SSH1 key exchange
 */
void
do_ssh1_kex(void)
{
	int i, len;
	int rsafail = 0;
	BIGNUM *session_key_int;
	u_char session_key[SSH_SESSION_KEY_LENGTH];
	u_char cookie[8];
	u_int cipher_type, auth_mask, protocol_flags;
	u_int32_t rnd = 0;

	/*
	 * Generate check bytes that the client must send back in the user
	 * packet in order for it to be accepted; this is used to defy ip
	 * spoofing attacks.  Note that this only works against somebody
	 * doing IP spoofing from a remote machine; any machine on the local
	 * network can still see outgoing packets and catch the random
	 * cookie.  This only affects rhosts authentication, and this is one
	 * of the reasons why it is inherently insecure.
	 */
	for (i = 0; i < 8; i++) {
		if (i % 4 == 0)
			rnd = arc4random();
		cookie[i] = rnd & 0xff;
		rnd >>= 8;
	}

	/*
	 * Send our public key.  We include in the packet 64 bits of random
	 * data that must be matched in the reply in order to prevent IP
	 * spoofing.
	 */
	packet_start(SSH_SMSG_PUBLIC_KEY);
	for (i = 0; i < 8; i++)
		packet_put_char(cookie[i]);

	/* Store our public server RSA key. */
	packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
	packet_put_bignum(sensitive_data.server_key->rsa->e);
	packet_put_bignum(sensitive_data.server_key->rsa->n);

	/* Store our public host RSA key. */
	packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
	packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
	packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);

	/* Put protocol flags. */
	packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);

	/* Declare which ciphers we support. */
	packet_put_int(cipher_mask_ssh1(0));

	/* Declare supported authentication types. */
	auth_mask = 0;
	if (options.rhosts_rsa_authentication)
		auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
	if (options.rsa_authentication)
		auth_mask |= 1 << SSH_AUTH_RSA;
	if (options.challenge_response_authentication == 1)
		auth_mask |= 1 << SSH_AUTH_TIS;
	if (options.password_authentication)
		auth_mask |= 1 << SSH_AUTH_PASSWORD;
	packet_put_int(auth_mask);

	/* Send the packet and wait for it to be sent. */
	packet_send();
	packet_write_wait();

	debug("Sent %d bit server key and %d bit host key.",
	    BN_num_bits(sensitive_data.server_key->rsa->n),
	    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));

	/* Read clients reply (cipher type and session key). */
	packet_read_expect(SSH_CMSG_SESSION_KEY);

	/* Get cipher type and check whether we accept this. */
	cipher_type = packet_get_char();

	if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
		packet_disconnect("Warning: client selects unsupported cipher.");

	/* Get check bytes from the packet.  These must match those we
	   sent earlier with the public key packet. */
	for (i = 0; i < 8; i++)
		if (cookie[i] != packet_get_char())
			packet_disconnect("IP Spoofing check bytes do not match.");

	debug("Encryption type: %.200s", cipher_name(cipher_type));

	/* Get the encrypted integer. */
	if ((session_key_int = BN_new()) == NULL)
		fatal("do_ssh1_kex: BN_new failed");
	packet_get_bignum(session_key_int);

	protocol_flags = packet_get_int();
	packet_set_protocol_flags(protocol_flags);
	packet_check_eom();
//.........这里部分代码省略.........

void
kexdh_server(Kex *kex)
{
	BIGNUM *sha