remote.c
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remote.c
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	/*
	* Copyright 2008-2024 the Pacemaker project contributors
	*
	* The version control history for this file may have further details.
	*
	* This source code is licensed under the GNU Lesser General Public License
	* version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
	*/

	#include <crm_internal.h>
	#include <crm/crm.h>

	#include <sys/param.h>
	#include <stdio.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <unistd.h>
	#include <sys/socket.h>
	#include <arpa/inet.h>
	#include <netinet/in.h>
	#include <netinet/ip.h>
	#include <netinet/tcp.h>
	#include <netdb.h>
	#include <stdlib.h>
	#include <errno.h>
	#include <inttypes.h> // PRIx32

	#include <glib.h>
	#include <bzlib.h>

	#include <crm/common/ipc_internal.h>
	#include <crm/common/xml.h>
	#include <crm/common/mainloop.h>
	#include <crm/common/remote_internal.h>

	#ifdef HAVE_GNUTLS_GNUTLS_H
	# include <gnutls/gnutls.h>
	#endif

	/* Swab macros from linux/swab.h */
	#ifdef HAVE_LINUX_SWAB_H
	# include <linux/swab.h>
	#else
	/*
	* casts are necessary for constants, because we never know how for sure
	* how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
	*/
	#define __swab16(x) ((uint16_t)( \
	(((uint16_t)(x) & (uint16_t)0x00ffU) << 8) \| \
	(((uint16_t)(x) & (uint16_t)0xff00U) >> 8)))

	#define __swab32(x) ((uint32_t)( \
	(((uint32_t)(x) & (uint32_t)0x000000ffUL) << 24) \| \
	(((uint32_t)(x) & (uint32_t)0x0000ff00UL) << 8) \| \
	(((uint32_t)(x) & (uint32_t)0x00ff0000UL) >> 8) \| \
	(((uint32_t)(x) & (uint32_t)0xff000000UL) >> 24)))

	#define __swab64(x) ((uint64_t)( \
	(((uint64_t)(x) & (uint64_t)0x00000000000000ffULL) << 56) \| \
	(((uint64_t)(x) & (uint64_t)0x000000000000ff00ULL) << 40) \| \
	(((uint64_t)(x) & (uint64_t)0x0000000000ff0000ULL) << 24) \| \
	(((uint64_t)(x) & (uint64_t)0x00000000ff000000ULL) << 8) \| \
	(((uint64_t)(x) & (uint64_t)0x000000ff00000000ULL) >> 8) \| \
	(((uint64_t)(x) & (uint64_t)0x0000ff0000000000ULL) >> 24) \| \
	(((uint64_t)(x) & (uint64_t)0x00ff000000000000ULL) >> 40) \| \
	(((uint64_t)(x) & (uint64_t)0xff00000000000000ULL) >> 56)))
	#endif

	#define REMOTE_MSG_VERSION 1
	#define ENDIAN_LOCAL 0xBADADBBD

	struct remote_header_v0 {
	uint32_t endian; /* Detect messages from hosts with different endian-ness */
	uint32_t version;
	uint64_t id;
	uint64_t flags;
	uint32_t size_total;
	uint32_t payload_offset;
	uint32_t payload_compressed;
	uint32_t payload_uncompressed;

	/* New fields get added here */

	} __attribute__ ((packed));

	/*!
	* \internal
	* \brief Retrieve remote message header, in local endianness
	*
	* Return a pointer to the header portion of a remote connection's message
	* buffer, converting the header to local endianness if needed.
	*
	* \param[in,out] remote Remote connection with new message
	*
	* \return Pointer to message header, localized if necessary
	*/
	static struct remote_header_v0 *
	localized_remote_header(pcmk__remote_t *remote)
	{
	struct remote_header_v0 header = (struct remote_header_v0 )remote->buffer;
	if(remote->buffer_offset < sizeof(struct remote_header_v0)) {
	return NULL;

	} else if(header->endian != ENDIAN_LOCAL) {
	uint32_t endian = __swab32(header->endian);

	CRM_LOG_ASSERT(endian == ENDIAN_LOCAL);
	if(endian != ENDIAN_LOCAL) {
	crm_err("Invalid message detected, endian mismatch: %" PRIx32
	" is neither %" PRIx32 " nor the swab'd %" PRIx32,
	ENDIAN_LOCAL, header->endian, endian);
	return NULL;
	}

	header->id = __swab64(header->id);
	header->flags = __swab64(header->flags);
	header->endian = __swab32(header->endian);

	header->version = __swab32(header->version);
	header->size_total = __swab32(header->size_total);
	header->payload_offset = __swab32(header->payload_offset);
	header->payload_compressed = __swab32(header->payload_compressed);
	header->payload_uncompressed = __swab32(header->payload_uncompressed);
	}

	return header;
	}

	#ifdef HAVE_GNUTLS_GNUTLS_H

	int
	pcmk__tls_client_try_handshake(pcmk__remote_t remote, int gnutls_rc)
	{
	int rc = pcmk_rc_ok;

	if (gnutls_rc != NULL) {
	*gnutls_rc = GNUTLS_E_SUCCESS;
	}

	rc = gnutls_handshake(*remote->tls_session);

	switch (rc) {
	case GNUTLS_E_SUCCESS:
	rc = pcmk_rc_ok;
	break;

	case GNUTLS_E_INTERRUPTED:
	case GNUTLS_E_AGAIN:
	rc = EAGAIN;
	break;

	default:
	if (gnutls_rc != NULL) {
	*gnutls_rc = rc;
	}

	rc = EPROTO;
	break;
	}

	return rc;
	}

	int pcmk__tls_client_handshake(pcmk__remote_t *remote, int timeout_sec,
	int *gnutls_rc)
	{
	const time_t time_limit = time(NULL) + timeout_sec;

	do {
	int rc = pcmk__tls_client_try_handshake(remote, gnutls_rc);

	if (rc != EAGAIN) {
	return rc;
	}
	} while (time(NULL) < time_limit);

	return ETIME;
	}

	/*!
	* \internal
	* \brief Set minimum prime size required by TLS client
	*
	* \param[in] session TLS session to affect
	*/
	static void
	set_minimum_dh_bits(const gnutls_session_t *session)
	{
	int dh_min_bits;

	pcmk__scan_min_int(pcmk__env_option(PCMK__ENV_DH_MIN_BITS), &dh_min_bits,
	0);

	/* This function is deprecated since GnuTLS 3.1.7, in favor of letting
	* the priority string imply the DH requirements, but this is the only
	* way to give the user control over compatibility with older servers.
	*/
	if (dh_min_bits > 0) {
	crm_info("Requiring server use a Diffie-Hellman prime of at least %d bits",
	dh_min_bits);
	crm_warn("Support for the " PCMK__ENV_DH_MIN_BITS " "
	"environment variable is deprecated and will be removed "
	"in a future release");
	gnutls_dh_set_prime_bits(*session, dh_min_bits);
	}
	}

	static unsigned int
	get_bound_dh_bits(unsigned int dh_bits)
	{
	int dh_min_bits;
	int dh_max_bits;

	pcmk__scan_min_int(pcmk__env_option(PCMK__ENV_DH_MIN_BITS), &dh_min_bits,
	0);
	pcmk__scan_min_int(pcmk__env_option(PCMK__ENV_DH_MAX_BITS), &dh_max_bits,
	0);

	if ((dh_max_bits > 0) && (dh_max_bits < dh_min_bits)) {
	crm_warn("Ignoring PCMK_dh_max_bits less than PCMK_dh_min_bits");
	dh_max_bits = 0;
	}
	if ((dh_min_bits > 0) && (dh_bits < dh_min_bits)) {
	return dh_min_bits;
	}
	if ((dh_max_bits > 0) && (dh_bits > dh_max_bits)) {
	return dh_max_bits;
	}
	return dh_bits;
	}

	/*!
	* \internal
	* \brief Initialize a new TLS session
	*
	* \param[in] csock Connected socket for TLS session
	* \param[in] conn_type GNUTLS_SERVER or GNUTLS_CLIENT
	* \param[in] cred_type GNUTLS_CRD_ANON or GNUTLS_CRD_PSK
	* \param[in] credentials TLS session credentials
	*
	* \return Pointer to newly created session object, or NULL on error
	*/
	gnutls_session_t *
	pcmk__new_tls_session(int csock, unsigned int conn_type,
	gnutls_credentials_type_t cred_type, void *credentials)
	{
	int rc = GNUTLS_E_SUCCESS;
	const char *prio_base = NULL;
	char *prio = NULL;
	gnutls_session_t *session = NULL;

	/* Determine list of acceptable ciphers, etc. Pacemaker always adds the
	* values required for its functionality.
	*
	* For an example of anonymous authentication, see:
	* http://www.manpagez.com/info/gnutls/gnutls-2.10.4/gnutls_81.php#Echo-Server-with-anonymous-authentication
	*/

	prio_base = pcmk__env_option(PCMK__ENV_TLS_PRIORITIES);
	if (prio_base == NULL) {
	prio_base = PCMK_GNUTLS_PRIORITIES;
	}
	prio = crm_strdup_printf("%s:%s", prio_base,
	(cred_type == GNUTLS_CRD_ANON)? "+ANON-DH" : "+DHE-PSK:+PSK");

	session = gnutls_malloc(sizeof(gnutls_session_t));
	if (session == NULL) {
	rc = GNUTLS_E_MEMORY_ERROR;
	goto error;
	}

	rc = gnutls_init(session, conn_type);
	if (rc != GNUTLS_E_SUCCESS) {
	goto error;
	}

	/* @TODO On the server side, it would be more efficient to cache the
	* priority with gnutls_priority_init2() and set it with
	* gnutls_priority_set() for all sessions.
	*/
	rc = gnutls_priority_set_direct(*session, prio, NULL);
	if (rc != GNUTLS_E_SUCCESS) {
	goto error;
	}
	if (conn_type == GNUTLS_CLIENT) {
	set_minimum_dh_bits(session);
	}

	gnutls_transport_set_ptr(*session,
	(gnutls_transport_ptr_t) GINT_TO_POINTER(csock));

	rc = gnutls_credentials_set(*session, cred_type, credentials);
	if (rc != GNUTLS_E_SUCCESS) {
	goto error;
	}
	free(prio);
	return session;

	error:
	crm_err("Could not initialize %s TLS %s session: %s "
	CRM_XS " rc=%d priority='%s'",
	(cred_type == GNUTLS_CRD_ANON)? "anonymous" : "PSK",
	(conn_type == GNUTLS_SERVER)? "server" : "client",
	gnutls_strerror(rc), rc, prio);
	free(prio);
	if (session != NULL) {
	gnutls_free(session);
	}
	return NULL;
	}

	/*!
	* \internal
	* \brief Initialize Diffie-Hellman parameters for a TLS server
	*
	* \param[out] dh_params Parameter object to initialize
	*
	* \return Standard Pacemaker return code
	* \todo The current best practice is to allow the client and server to
	* negotiate the Diffie-Hellman parameters via a TLS extension (RFC 7919).
	* However, we have to support both older versions of GnuTLS (<3.6) that
	* don't support the extension on our side, and older Pacemaker versions
	* that don't support the extension on the other side. The next best
	* practice would be to use a known good prime (see RFC 5114 section 2.2),
	* possibly stored in a file distributed with Pacemaker.
	*/
	int
	pcmk__init_tls_dh(gnutls_dh_params_t *dh_params)
	{
	int rc = GNUTLS_E_SUCCESS;
	unsigned int dh_bits = 0;

	rc = gnutls_dh_params_init(dh_params);
	if (rc != GNUTLS_E_SUCCESS) {
	goto error;
	}

	dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
	GNUTLS_SEC_PARAM_NORMAL);
	if (dh_bits == 0) {
	rc = GNUTLS_E_DH_PRIME_UNACCEPTABLE;
	goto error;
	}
	dh_bits = get_bound_dh_bits(dh_bits);

	crm_info("Generating Diffie-Hellman parameters with %u-bit prime for TLS",
	dh_bits);
	rc = gnutls_dh_params_generate2(*dh_params, dh_bits);
	if (rc != GNUTLS_E_SUCCESS) {
	goto error;
	}

	return pcmk_rc_ok;

	error:
	crm_err("Could not initialize Diffie-Hellman parameters for TLS: %s "
	CRM_XS " rc=%d", gnutls_strerror(rc), rc);
	return EPROTO;
	}

	/*!
	* \internal
	* \brief Process handshake data from TLS client
	*
	* Read as much TLS handshake data as is available.
	*
	* \param[in] client Client connection
	*
	* \return Standard Pacemaker return code (of particular interest, EAGAIN
	* if some data was successfully read but more data is needed)
	*/
	int
	pcmk__read_handshake_data(const pcmk__client_t *client)
	{
	int rc = 0;

	CRM_ASSERT(client && client->remote && client->remote->tls_session);

	do {
	rc = gnutls_handshake(*client->remote->tls_session);
	} while (rc == GNUTLS_E_INTERRUPTED);

	if (rc == GNUTLS_E_AGAIN) {
	/* No more data is available at the moment. This function should be
	* invoked again once the client sends more.
	*/
	return EAGAIN;
	} else if (rc != GNUTLS_E_SUCCESS) {
	crm_err("TLS handshake with remote client failed: %s "
	CRM_XS " rc=%d", gnutls_strerror(rc), rc);
	return EPROTO;
	}
	return pcmk_rc_ok;
	}

	// \return Standard Pacemaker return code
	static int
	send_tls(gnutls_session_t session, struct iovec iov)
	{
	const char *unsent = iov->iov_base;
	size_t unsent_len = iov->iov_len;
	ssize_t gnutls_rc;

	if (unsent == NULL) {
	return EINVAL;
	}

	crm_trace("Sending TLS message of %llu bytes",
	(unsigned long long) unsent_len);
	while (true) {
	gnutls_rc = gnutls_record_send(*session, unsent, unsent_len);

	if (gnutls_rc == GNUTLS_E_INTERRUPTED \|\| gnutls_rc == GNUTLS_E_AGAIN) {
	crm_trace("Retrying to send %llu bytes remaining",
	(unsigned long long) unsent_len);

	} else if (gnutls_rc < 0) {
	// Caller can log as error if necessary
	crm_info("TLS connection terminated: %s " CRM_XS " rc=%lld",
	gnutls_strerror((int) gnutls_rc),
	(long long) gnutls_rc);
	return ECONNABORTED;

	} else if (gnutls_rc < unsent_len) {
	crm_trace("Sent %lld of %llu bytes remaining",
	(long long) gnutls_rc, (unsigned long long) unsent_len);
	unsent_len -= gnutls_rc;
	unsent += gnutls_rc;
	} else {
	crm_trace("Sent all %lld bytes remaining", (long long) gnutls_rc);
	break;
	}
	}
	return pcmk_rc_ok;
	}
	#endif

	// \return Standard Pacemaker return code
	static int
	send_plaintext(int sock, struct iovec *iov)
	{
	const char *unsent = iov->iov_base;
	size_t unsent_len = iov->iov_len;
	ssize_t write_rc;

	if (unsent == NULL) {
	return EINVAL;
	}

	crm_debug("Sending plaintext message of %llu bytes to socket %d",
	(unsigned long long) unsent_len, sock);
	while (true) {
	write_rc = write(sock, unsent, unsent_len);
	if (write_rc < 0) {
	int rc = errno;

	if ((errno == EINTR) \|\| (errno == EAGAIN)) {
	crm_trace("Retrying to send %llu bytes remaining to socket %d",
	(unsigned long long) unsent_len, sock);
	continue;
	}

	// Caller can log as error if necessary
	crm_info("Could not send message: %s " CRM_XS " rc=%d socket=%d",
	pcmk_rc_str(rc), rc, sock);
	return rc;

	} else if (write_rc < unsent_len) {
	crm_trace("Sent %lld of %llu bytes remaining",
	(long long) write_rc, (unsigned long long) unsent_len);
	unsent += write_rc;
	unsent_len -= write_rc;
	continue;

	} else {
	crm_trace("Sent all %lld bytes remaining: %.100s",
	(long long) write_rc, (char *) (iov->iov_base));
	break;
	}
	}
	return pcmk_rc_ok;
	}

	// \return Standard Pacemaker return code
	static int
	remote_send_iovs(pcmk__remote_t remote, struct iovec iov, int iovs)
	{
	int rc = pcmk_rc_ok;

	for (int lpc = 0; (lpc < iovs) && (rc == pcmk_rc_ok); lpc++) {
	#ifdef HAVE_GNUTLS_GNUTLS_H
	if (remote->tls_session) {
	rc = send_tls(remote->tls_session, &(iov[lpc]));
	continue;
	}
	#endif
	if (remote->tcp_socket) {
	rc = send_plaintext(remote->tcp_socket, &(iov[lpc]));
	} else {
	rc = ESOCKTNOSUPPORT;
	}
	}
	return rc;
	}

	/*!
	* \internal
	* \brief Send an XML message over a Pacemaker Remote connection
	*
	* \param[in,out] remote Pacemaker Remote connection to use
	* \param[in] msg XML to send
	*
	* \return Standard Pacemaker return code
	*/
	int
	pcmk__remote_send_xml(pcmk__remote_t remote, const xmlNode msg)
	{
	int rc = pcmk_rc_ok;
	static uint64_t id = 0;
	GString *xml_text = NULL;

	struct iovec iov[2];
	struct remote_header_v0 *header;

	CRM_CHECK((remote != NULL) && (msg != NULL), return EINVAL);

	xml_text = g_string_sized_new(1024);
	pcmk__xml_string(msg, 0, xml_text, 0);
	CRM_CHECK(xml_text->len > 0,
	g_string_free(xml_text, TRUE); return EINVAL);

	header = pcmk__assert_alloc(1, sizeof(struct remote_header_v0));

	iov[0].iov_base = header;
	iov[0].iov_len = sizeof(struct remote_header_v0);

	iov[1].iov_len = 1 + xml_text->len;
	iov[1].iov_base = g_string_free(xml_text, FALSE);

	id++;
	header->id = id;
	header->endian = ENDIAN_LOCAL;
	header->version = REMOTE_MSG_VERSION;
	header->payload_offset = iov[0].iov_len;
	header->payload_uncompressed = iov[1].iov_len;
	header->size_total = iov[0].iov_len + iov[1].iov_len;

	rc = remote_send_iovs(remote, iov, 2);
	if (rc != pcmk_rc_ok) {
	crm_err("Could not send remote message: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	}

	free(iov[0].iov_base);
	g_free((gchar *) iov[1].iov_base);
	return rc;
	}

	/*!
	* \internal
	* \brief Obtain the XML from the currently buffered remote connection message
	*
	* \param[in,out] remote Remote connection possibly with message available
	*
	* \return Newly allocated XML object corresponding to message data, or NULL
	* \note This effectively removes the message from the connection buffer.
	*/
	xmlNode *
	pcmk__remote_message_xml(pcmk__remote_t *remote)
	{
	xmlNode *xml = NULL;
	struct remote_header_v0 *header = localized_remote_header(remote);

	if (header == NULL) {
	return NULL;
	}

	/* Support compression on the receiving end now, in case we ever want to add it later */
	if (header->payload_compressed) {
	int rc = 0;
	unsigned int size_u = 1 + header->payload_uncompressed;
	char *uncompressed =
	pcmk__assert_alloc(1, header->payload_offset + size_u);

	crm_trace("Decompressing message data %d bytes into %d bytes",
	header->payload_compressed, size_u);

	rc = BZ2_bzBuffToBuffDecompress(uncompressed + header->payload_offset, &size_u,
	remote->buffer + header->payload_offset,
	header->payload_compressed, 1, 0);
	rc = pcmk__bzlib2rc(rc);

	if (rc != pcmk_rc_ok && header->version > REMOTE_MSG_VERSION) {
	crm_warn("Couldn't decompress v%d message, we only understand v%d",
	header->version, REMOTE_MSG_VERSION);
	free(uncompressed);
	return NULL;

	} else if (rc != pcmk_rc_ok) {
	crm_err("Decompression failed: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	free(uncompressed);
	return NULL;
	}

	CRM_ASSERT(size_u == header->payload_uncompressed);

	memcpy(uncompressed, remote->buffer, header->payload_offset); /* Preserve the header */
	remote->buffer_size = header->payload_offset + size_u;

	free(remote->buffer);
	remote->buffer = uncompressed;
	header = localized_remote_header(remote);
	}

	/* take ownership of the buffer */
	remote->buffer_offset = 0;

	CRM_LOG_ASSERT(remote->buffer[sizeof(struct remote_header_v0) + header->payload_uncompressed - 1] == 0);

	xml = pcmk__xml_parse(remote->buffer + header->payload_offset);
	if (xml == NULL && header->version > REMOTE_MSG_VERSION) {
	crm_warn("Couldn't parse v%d message, we only understand v%d",
	header->version, REMOTE_MSG_VERSION);

	} else if (xml == NULL) {
	crm_err("Couldn't parse: '%.120s'", remote->buffer + header->payload_offset);
	}

	return xml;
	}

	static int
	get_remote_socket(const pcmk__remote_t *remote)
	{
	#ifdef HAVE_GNUTLS_GNUTLS_H
	if (remote->tls_session) {
	void sock_ptr = gnutls_transport_get_ptr(remote->tls_session);

	return GPOINTER_TO_INT(sock_ptr);
	}
	#endif

	if (remote->tcp_socket) {
	return remote->tcp_socket;
	}

	crm_err("Remote connection type undetermined (bug?)");
	return -1;
	}

	/*!
	* \internal
	* \brief Wait for a remote session to have data to read
	*
	* \param[in] remote Connection to check
	* \param[in] timeout_ms Maximum time (in ms) to wait
	*
	* \return Standard Pacemaker return code (of particular interest, pcmk_rc_ok if
	* there is data ready to be read, and ETIME if there is no data within
	* the specified timeout)
	*/
	int
	pcmk__remote_ready(const pcmk__remote_t *remote, int timeout_ms)
	{
	struct pollfd fds = { 0, };
	int sock = 0;
	int rc = 0;
	time_t start;
	int timeout = timeout_ms;

	sock = get_remote_socket(remote);
	if (sock <= 0) {
	crm_trace("No longer connected");
	return ENOTCONN;
	}

	start = time(NULL);
	errno = 0;
	do {
	fds.fd = sock;
	fds.events = POLLIN;

	/* If we got an EINTR while polling, and we have a
	* specific timeout we are trying to honor, attempt
	* to adjust the timeout to the closest second. */
	if (errno == EINTR && (timeout > 0)) {
	timeout = timeout_ms - ((time(NULL) - start) * 1000);
	if (timeout < 1000) {
	timeout = 1000;
	}
	}

	rc = poll(&fds, 1, timeout);
	} while (rc < 0 && errno == EINTR);

	if (rc < 0) {
	return errno;
	}
	return (rc == 0)? ETIME : pcmk_rc_ok;
	}

	/*!
	* \internal
	* \brief Read bytes from non-blocking remote connection
	*
	* \param[in,out] remote Remote connection to read
	*
	* \return Standard Pacemaker return code (of particular interest, pcmk_rc_ok if
	* a full message has been received, or EAGAIN for a partial message)
	* \note Use only with non-blocking sockets after polling the socket.
	* \note This function will return when the socket read buffer is empty or an
	* error is encountered.
	*/
	static int
	read_available_remote_data(pcmk__remote_t *remote)
	{
	int rc = pcmk_rc_ok;
	size_t read_len = sizeof(struct remote_header_v0);
	struct remote_header_v0 *header = localized_remote_header(remote);
	bool received = false;
	ssize_t read_rc;

	if(header) {
	/* Stop at the end of the current message */
	read_len = header->size_total;
	}

	/* automatically grow the buffer when needed */
	if(remote->buffer_size < read_len) {
	remote->buffer_size = 2 * read_len;
	crm_trace("Expanding buffer to %llu bytes",
	(unsigned long long) remote->buffer_size);
	remote->buffer = pcmk__realloc(remote->buffer, remote->buffer_size + 1);
	}

	#ifdef HAVE_GNUTLS_GNUTLS_H
	if (!received && remote->tls_session) {
	read_rc = gnutls_record_recv(*(remote->tls_session),
	remote->buffer + remote->buffer_offset,
	remote->buffer_size - remote->buffer_offset);
	if (read_rc == GNUTLS_E_INTERRUPTED) {
	rc = EINTR;
	} else if (read_rc == GNUTLS_E_AGAIN) {
	rc = EAGAIN;
	} else if (read_rc < 0) {
	crm_debug("TLS receive failed: %s (%lld)",
	gnutls_strerror(read_rc), (long long) read_rc);
	rc = EIO;
	}
	received = true;
	}
	#endif

	if (!received && remote->tcp_socket) {
	read_rc = read(remote->tcp_socket,
	remote->buffer + remote->buffer_offset,
	remote->buffer_size - remote->buffer_offset);
	if (read_rc < 0) {
	rc = errno;
	}
	received = true;
	}

	if (!received) {
	crm_err("Remote connection type undetermined (bug?)");
	return ESOCKTNOSUPPORT;
	}

	/* process any errors. */
	if (read_rc > 0) {
	remote->buffer_offset += read_rc;
	/* always null terminate buffer, the +1 to alloc always allows for this. */
	remote->buffer[remote->buffer_offset] = '\0';
	crm_trace("Received %lld more bytes (%llu total)",
	(long long) read_rc,
	(unsigned long long) remote->buffer_offset);

	} else if ((rc == EINTR) \|\| (rc == EAGAIN)) {
	crm_trace("No data available for non-blocking remote read: %s (%d)",
	pcmk_rc_str(rc), rc);

	} else if (read_rc == 0) {
	crm_debug("End of remote data encountered after %llu bytes",
	(unsigned long long) remote->buffer_offset);
	return ENOTCONN;

	} else {
	crm_debug("Error receiving remote data after %llu bytes: %s (%d)",
	(unsigned long long) remote->buffer_offset,
	pcmk_rc_str(rc), rc);
	return ENOTCONN;
	}

	header = localized_remote_header(remote);
	if(header) {
	if(remote->buffer_offset < header->size_total) {
	crm_trace("Read partial remote message (%llu of %u bytes)",
	(unsigned long long) remote->buffer_offset,
	header->size_total);
	} else {
	crm_trace("Read full remote message of %llu bytes",
	(unsigned long long) remote->buffer_offset);
	return pcmk_rc_ok;
	}
	}

	return EAGAIN;
	}

	/*!
	* \internal
	* \brief Read one message from a remote connection
	*
	* \param[in,out] remote Remote connection to read
	* \param[in] timeout_ms Fail if message not read in this many milliseconds
	* (10s will be used if 0, and 60s if negative)
	*
	* \return Standard Pacemaker return code
	*/
	int
	pcmk__read_remote_message(pcmk__remote_t *remote, int timeout_ms)
	{
	int rc = pcmk_rc_ok;
	time_t start = time(NULL);
	int remaining_timeout = 0;

	if (timeout_ms == 0) {
	timeout_ms = 10000;
	} else if (timeout_ms < 0) {
	timeout_ms = 60000;
	}

	remaining_timeout = timeout_ms;
	while (remaining_timeout > 0) {

	crm_trace("Waiting for remote data (%d ms of %d ms timeout remaining)",
	remaining_timeout, timeout_ms);
	rc = pcmk__remote_ready(remote, remaining_timeout);

	if (rc == ETIME) {
	crm_err("Timed out (%d ms) while waiting for remote data",
	remaining_timeout);
	return rc;

	} else if (rc != pcmk_rc_ok) {
	crm_debug("Wait for remote data aborted (will retry): %s "
	CRM_XS " rc=%d", pcmk_rc_str(rc), rc);

	} else {
	rc = read_available_remote_data(remote);
	if (rc == pcmk_rc_ok) {
	return rc;
	} else if (rc == EAGAIN) {
	crm_trace("Waiting for more remote data");
	} else {
	crm_debug("Could not receive remote data: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	}
	}

	// Don't waste time retrying after fatal errors
	if ((rc == ENOTCONN) \|\| (rc == ESOCKTNOSUPPORT)) {
	return rc;
	}

	remaining_timeout = timeout_ms - ((time(NULL) - start) * 1000);
	}
	return ETIME;
	}

	struct tcp_async_cb_data {
	int sock;
	int timeout_ms;
	time_t start;
	void *userdata;
	void (callback) (void userdata, int rc, int sock);
	};

	// \return TRUE if timer should be rescheduled, FALSE otherwise
	static gboolean
	check_connect_finished(gpointer userdata)
	{
	struct tcp_async_cb_data *cb_data = userdata;
	int rc;

	fd_set rset, wset;
	struct timeval ts = { 0, };

	if (cb_data->start == 0) {
	// Last connect() returned success immediately
	rc = pcmk_rc_ok;
	goto dispatch_done;
	}

	// If the socket is ready for reading or writing, the connect succeeded
	FD_ZERO(&rset);
	FD_SET(cb_data->sock, &rset);
	wset = rset;
	rc = select(cb_data->sock + 1, &rset, &wset, NULL, &ts);

	if (rc < 0) { // select() error
	rc = errno;
	if ((rc == EINPROGRESS) \|\| (rc == EAGAIN)) {
	if ((time(NULL) - cb_data->start) < (cb_data->timeout_ms / 1000)) {
	return TRUE; // There is time left, so reschedule timer
	} else {
	rc = ETIMEDOUT;
	}
	}
	crm_trace("Could not check socket %d for connection success: %s (%d)",
	cb_data->sock, pcmk_rc_str(rc), rc);

	} else if (rc == 0) { // select() timeout
	if ((time(NULL) - cb_data->start) < (cb_data->timeout_ms / 1000)) {
	return TRUE; // There is time left, so reschedule timer
	}
	crm_debug("Timed out while waiting for socket %d connection success",
	cb_data->sock);
	rc = ETIMEDOUT;

	// select() returned number of file descriptors that are ready

	} else if (FD_ISSET(cb_data->sock, &rset)
	\|\| FD_ISSET(cb_data->sock, &wset)) {

	// The socket is ready; check it for connection errors
	int error = 0;
	socklen_t len = sizeof(error);

	if (getsockopt(cb_data->sock, SOL_SOCKET, SO_ERROR, &error, &len) < 0) {
	rc = errno;
	crm_trace("Couldn't check socket %d for connection errors: %s (%d)",
	cb_data->sock, pcmk_rc_str(rc), rc);
	} else if (error != 0) {
	rc = error;
	crm_trace("Socket %d connected with error: %s (%d)",
	cb_data->sock, pcmk_rc_str(rc), rc);
	} else {
	rc = pcmk_rc_ok;
	}

	} else { // Should not be possible
	crm_trace("select() succeeded, but socket %d not in resulting "
	"read/write sets", cb_data->sock);
	rc = EAGAIN;
	}

	dispatch_done:
	if (rc == pcmk_rc_ok) {
	crm_trace("Socket %d is connected", cb_data->sock);
	} else {
	close(cb_data->sock);
	cb_data->sock = -1;
	}

	if (cb_data->callback) {
	cb_data->callback(cb_data->userdata, rc, cb_data->sock);
	}
	free(cb_data);
	return FALSE; // Do not reschedule timer
	}

	/*!
	* \internal
	* \brief Attempt to connect socket, calling callback when done
	*
	* Set a given socket non-blocking, then attempt to connect to it,
	* retrying periodically until success or a timeout is reached.
	* Call a caller-supplied callback function when completed.
	*
	* \param[in] sock Newly created socket
	* \param[in] addr Socket address information for connect
	* \param[in] addrlen Size of socket address information in bytes
	* \param[in] timeout_ms Fail if not connected within this much time
	* \param[out] timer_id If not NULL, store retry timer ID here
	* \param[in] userdata User data to pass to callback
	* \param[in] callback Function to call when connection attempt completes
	*
	* \return Standard Pacemaker return code
	*/
	static int
	connect_socket_retry(int sock, const struct sockaddr *addr, socklen_t addrlen,
	int timeout_ms, int timer_id, void userdata,
	void (callback) (void userdata, int rc, int sock))
	{
	int rc = 0;
	int interval = 500;
	int timer;
	struct tcp_async_cb_data *cb_data = NULL;

	rc = pcmk__set_nonblocking(sock);
	if (rc != pcmk_rc_ok) {
	crm_warn("Could not set socket non-blocking: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	return rc;
	}

	rc = connect(sock, addr, addrlen);
	if (rc < 0 && (errno != EINPROGRESS) && (errno != EAGAIN)) {
	rc = errno;
	crm_warn("Could not connect socket: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	return rc;
	}

	cb_data = pcmk__assert_alloc(1, sizeof(struct tcp_async_cb_data));
	cb_data->userdata = userdata;
	cb_data->callback = callback;
	cb_data->sock = sock;
	cb_data->timeout_ms = timeout_ms;

	if (rc == 0) {
	/* The connect was successful immediately, we still return to mainloop
	* and let this callback get called later. This avoids the user of this api
	* to have to account for the fact the callback could be invoked within this
	* function before returning. */
	cb_data->start = 0;
	interval = 1;
	} else {
	cb_data->start = time(NULL);
	}

	/* This timer function does a non-blocking poll on the socket to see if we
	* can use it. Once we can, the connect has completed. This method allows us
	* to connect without blocking the mainloop.
	*
	* @TODO Use a mainloop fd callback for this instead of polling. Something
	* about the way mainloop is currently polling prevents this from
	* working at the moment though. (See connect(2) regarding EINPROGRESS
	* for possible new handling needed.)
	*/
	crm_trace("Scheduling check in %dms for whether connect to fd %d finished",
	interval, sock);
	timer = g_timeout_add(interval, check_connect_finished, cb_data);
	if (timer_id) {
	*timer_id = timer;
	}

	// timer callback should be taking care of cb_data
	// cppcheck-suppress memleak
	return pcmk_rc_ok;
	}

	/*!
	* \internal
	* \brief Attempt once to connect socket and set it non-blocking
	*
	* \param[in] sock Newly created socket
	* \param[in] addr Socket address information for connect
	* \param[in] addrlen Size of socket address information in bytes
	*
	* \return Standard Pacemaker return code
	*/
	static int
	connect_socket_once(int sock, const struct sockaddr *addr, socklen_t addrlen)
	{
	int rc = connect(sock, addr, addrlen);

	if (rc < 0) {
	rc = errno;
	crm_warn("Could not connect socket: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	return rc;
	}

	rc = pcmk__set_nonblocking(sock);
	if (rc != pcmk_rc_ok) {
	crm_warn("Could not set socket non-blocking: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	return rc;
	}

	return pcmk_ok;
	}

	/*!
	* \internal
	* \brief Connect to server at specified TCP port
	*
	* \param[in] host Name of server to connect to
	* \param[in] port Server port to connect to
	* \param[in] timeout_ms If asynchronous, fail if not connected in this time
	* \param[out] timer_id If asynchronous and this is non-NULL, retry timer ID
	* will be put here (for ease of cancelling by caller)
	* \param[out] sock_fd Where to store socket file descriptor
	* \param[in] userdata If asynchronous, data to pass to callback
	* \param[in] callback If NULL, attempt a single synchronous connection,
	* otherwise retry asynchronously then call this
	*
	* \return Standard Pacemaker return code
	*/
	int
	pcmk__connect_remote(const char host, int port, int timeout, int timer_id,
	int sock_fd, void userdata,
	void (callback) (void userdata, int rc, int sock))
	{
	char buffer[INET6_ADDRSTRLEN];
	struct addrinfo *res = NULL;
	struct addrinfo *rp = NULL;
	struct addrinfo hints;
	const char *server = host;
	int rc;
	int sock = -1;

	CRM_CHECK((host != NULL) && (sock_fd != NULL), return EINVAL);

	// Get host's IP address(es)
	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_CANONNAME;

	rc = getaddrinfo(server, NULL, &hints, &res);
	rc = pcmk__gaierror2rc(rc);

	if (rc != pcmk_rc_ok) {
	crm_err("Unable to get IP address info for %s: %s",
	server, pcmk_rc_str(rc));
	goto async_cleanup;
	}

	if (!res \|\| !res->ai_addr) {
	crm_err("Unable to get IP address info for %s: no result", server);
	rc = ENOTCONN;
	goto async_cleanup;
	}

	// getaddrinfo() returns a list of host's addresses, try them in order
	for (rp = res; rp != NULL; rp = rp->ai_next) {
	struct sockaddr *addr = rp->ai_addr;

	if (!addr) {
	continue;
	}

	if (rp->ai_canonname) {
	server = res->ai_canonname;
	}
	crm_debug("Got canonical name %s for %s", server, host);

	sock = socket(rp->ai_family, SOCK_STREAM, IPPROTO_TCP);
	if (sock == -1) {
	rc = errno;
	crm_warn("Could not create socket for remote connection to %s:%d: "
	"%s " CRM_XS " rc=%d", server, port, pcmk_rc_str(rc), rc);
	continue;
	}

	/* Set port appropriately for address family */
	/* (void) casts avoid false-positive compiler alignment warnings /
	if (addr->sa_family == AF_INET6) {
	((struct sockaddr_in6 )(void)addr)->sin6_port = htons(port);
	} else {
	((struct sockaddr_in )(void)addr)->sin_port = htons(port);
	}

	memset(buffer, 0, PCMK__NELEM(buffer));
	pcmk__sockaddr2str(addr, buffer);
	crm_info("Attempting remote connection to %s:%d", buffer, port);

	if (callback) {
	if (connect_socket_retry(sock, rp->ai_addr, rp->ai_addrlen, timeout,
	timer_id, userdata, callback) == pcmk_rc_ok) {
	goto async_cleanup; /* Success for now, we'll hear back later in the callback */
	}

	} else if (connect_socket_once(sock, rp->ai_addr,
	rp->ai_addrlen) == pcmk_rc_ok) {
	break; /* Success */
	}

	// Connect failed
	close(sock);
	sock = -1;
	rc = ENOTCONN;
	}

	async_cleanup:

	if (res) {
	freeaddrinfo(res);
	}
	*sock_fd = sock;
	return rc;
	}

	/*!
	* \internal
	* \brief Convert an IP address (IPv4 or IPv6) to a string for logging
	*
	* \param[in] sa Socket address for IP
	* \param[out] s Storage for at least INET6_ADDRSTRLEN bytes
	*
	* \note sa The socket address can be a pointer to struct sockaddr_in (IPv4),
	* struct sockaddr_in6 (IPv6) or struct sockaddr_storage (either),
	* as long as its sa_family member is set correctly.
	*/
	void
	pcmk__sockaddr2str(const void sa, char s)
	{
	switch (((const struct sockaddr *) sa)->sa_family) {
	case AF_INET:
	inet_ntop(AF_INET, &(((const struct sockaddr_in *) sa)->sin_addr),
	s, INET6_ADDRSTRLEN);
	break;

	case AF_INET6:
	inet_ntop(AF_INET6,
	&(((const struct sockaddr_in6 *) sa)->sin6_addr),
	s, INET6_ADDRSTRLEN);
	break;

	default:
	strcpy(s, "<invalid>");
	}
	}

	/*!
	* \internal
	* \brief Accept a client connection on a remote server socket
	*
	* \param[in] ssock Server socket file descriptor being listened on
	* \param[out] csock Where to put new client socket's file descriptor
	*
	* \return Standard Pacemaker return code
	*/
	int
	pcmk__accept_remote_connection(int ssock, int *csock)
	{
	int rc;
	struct sockaddr_storage addr;
	socklen_t laddr = sizeof(addr);
	char addr_str[INET6_ADDRSTRLEN];
	#ifdef TCP_USER_TIMEOUT
	long sbd_timeout = 0;
	#endif

	/* accept the connection */
	memset(&addr, 0, sizeof(addr));
	csock = accept(ssock, (struct sockaddr )&addr, &laddr);
	if (*csock == -1) {
	rc = errno;
	crm_err("Could not accept remote client connection: %s "
	CRM_XS " rc=%d", pcmk_rc_str(rc), rc);
	return rc;
	}
	pcmk__sockaddr2str(&addr, addr_str);
	crm_info("Accepted new remote client connection from %s", addr_str);

	rc = pcmk__set_nonblocking(*csock);
	if (rc != pcmk_rc_ok) {
	crm_err("Could not set socket non-blocking: %s " CRM_XS " rc=%d",
	pcmk_rc_str(rc), rc);
	close(*csock);
	*csock = -1;
	return rc;
	}

	#ifdef TCP_USER_TIMEOUT
	sbd_timeout = pcmk__get_sbd_watchdog_timeout();
	if (sbd_timeout > 0) {
	// Time to fail and retry before watchdog
	long half = sbd_timeout / 2;
	unsigned int optval = (half <= UINT_MAX)? half : UINT_MAX;

	rc = setsockopt(*csock, SOL_TCP, TCP_USER_TIMEOUT,
	&optval, sizeof(optval));
	if (rc < 0) {
	rc = errno;
	crm_err("Could not set TCP timeout to %d ms on remote connection: "
	"%s " CRM_XS " rc=%d", optval, pcmk_rc_str(rc), rc);
	close(*csock);
	*csock = -1;
	return rc;
	}
	}
	#endif

	return rc;
	}

	/*!
	* \brief Get the default remote connection TCP port on this host
	*
	* \return Remote connection TCP port number
	*/
	int
	crm_default_remote_port(void)
	{
	static int port = 0;

	if (port == 0) {
	const char *env = pcmk__env_option(PCMK__ENV_REMOTE_PORT);

	if (env) {
	errno = 0;
	port = strtol(env, NULL, 10);
	if (errno \|\| (port < 1) \|\| (port > 65535)) {
	crm_warn("Environment variable PCMK_" PCMK__ENV_REMOTE_PORT
	" has invalid value '%s', using %d instead",
	env, DEFAULT_REMOTE_PORT);
	port = DEFAULT_REMOTE_PORT;
	}
	} else {
	port = DEFAULT_REMOTE_PORT;
	}
	}
	return port;
	}

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