src/checks.c

/*
 * Health-checks functions.
 *
 * Copyright 2000-2006 Willy Tarreau <w@1wt.eu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 */

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <common/compat.h>
#include <common/config.h>
#include <common/mini-clist.h>
#include <common/time.h>

#include <types/global.h>
#include <types/polling.h>
#include <types/proxy.h>
#include <types/session.h>

#include <proto/backend.h>
#include <proto/fd.h>
#include <proto/log.h>
#include <proto/queue.h>
#include <proto/server.h>
#include <proto/task.h>


/* Sets server <s> down, notifies by all available means, recounts the
 * remaining servers on the proxy and transfers queued sessions whenever
 * possible to other servers.
 */
void set_server_down(struct server *s)
{
	struct pendconn *pc, *pc_bck, *pc_end;
	struct session *sess;
	int xferred;

	s->state &= ~SRV_RUNNING;

	if (s->health == s->rise) {
		recount_servers(s->proxy);
		recalc_server_map(s->proxy);

		/* we might have sessions queued on this server and waiting for
		 * a connection. Those which are redispatchable will be queued
		 * to another server or to the proxy itself.
		 */
		xferred = 0;
		FOREACH_ITEM_SAFE(pc, pc_bck, &s->pendconns, pc_end, struct pendconn *, list) {
			sess = pc->sess;
			if ((sess->proxy->options & PR_O_REDISP)) {
				/* The REDISP option was specified. We will ignore
				 * cookie and force to balance or use the dispatcher.
				 */
				sess->flags &= ~(SN_DIRECT | SN_ASSIGNED | SN_ADDR_SET);
				sess->srv = NULL; /* it's left to the dispatcher to choose a server */
				if ((sess->flags & SN_CK_MASK) == SN_CK_VALID) {
					sess->flags &= ~SN_CK_MASK;
					sess->flags |= SN_CK_DOWN;
				}
				pendconn_free(pc);
				task_wakeup(&rq, sess->task);
				xferred++;
			}
		}

		sprintf(trash, "%sServer %s/%s is DOWN. %d active and %d backup servers left.%s"
			" %d sessions active, %d requeued, %d remaining in queue.\n",
			s->state & SRV_BACKUP ? "Backup " : "",
			s->proxy->id, s->id, s->proxy->srv_act, s->proxy->srv_bck,
			(s->proxy->srv_bck && !s->proxy->srv_act) ? " Running on backup." : "",
			s->cur_sess, xferred, s->nbpend);

		Warning("%s", trash);
		send_log(s->proxy, LOG_ALERT, "%s", trash);
	
		if (s->proxy->srv_bck == 0 && s->proxy->srv_act == 0) {
			Alert("Proxy %s has no server available !\n", s->proxy->id);
			send_log(s->proxy, LOG_EMERG, "Proxy %s has no server available !\n", s->proxy->id);
		}
		s->down_trans++;
	}
	s->health = 0; /* failure */
}


/*
 * This function is used only for server health-checks. It handles
 * the connection acknowledgement. If the proxy requires HTTP health-checks,
 * it sends the request. In other cases, it returns 1 if the socket is OK,
 * or -1 if an error occured.
 */
int event_srv_chk_w(int fd)
{
	struct task *t = fdtab[fd].owner;
	struct server *s = t->context;
	int skerr;
	socklen_t lskerr = sizeof(skerr);

	skerr = 1;
	if ((getsockopt(fd, SOL_SOCKET, SO_ERROR, &skerr, &lskerr) == -1)
	    || (skerr != 0)) {
		/* in case of TCP only, this tells us if the connection failed */
		s->result = -1;
		fdtab[fd].state = FD_STERROR;
		FD_CLR(fd, StaticWriteEvent);
	}
	else if (s->result != -1) {
		/* we don't want to mark 'UP' a server on which we detected an error earlier */
		if ((s->proxy->options & PR_O_HTTP_CHK) ||
		    (s->proxy->options & PR_O_SSL3_CHK)) {
			int ret;
			/* we want to check if this host replies to HTTP or SSLv3 requests
			 * so we'll send the request, and won't wake the checker up now.
			 */

			if (s->proxy->options & PR_O_SSL3_CHK) {
				/* SSL requires that we put Unix time in the request */
				int gmt_time = htonl(now.tv_sec);
				memcpy(s->proxy->check_req + 11, &gmt_time, 4);
			}

#ifndef MSG_NOSIGNAL
			ret = send(fd, s->proxy->check_req, s->proxy->check_len, MSG_DONTWAIT);
#else
			ret = send(fd, s->proxy->check_req, s->proxy->check_len, MSG_DONTWAIT | MSG_NOSIGNAL);
#endif
			if (ret == s->proxy->check_len) {
				FD_SET(fd, StaticReadEvent);   /* prepare for reading reply */
				FD_CLR(fd, StaticWriteEvent);  /* nothing more to write */
				return 0;
			}
			else {
				s->result = -1;
				FD_CLR(fd, StaticWriteEvent);
			}
		}
		else {
			/* good TCP connection is enough */
			s->result = 1;
		}
	}

	task_wakeup(&rq, t);
	return 0;
}


/*
 * This function is used only for server health-checks. It handles the server's
 * reply to an HTTP request or SSL HELLO. It returns 1 in s->result if the
 * server replies HTTP 2xx or 3xx (valid responses), or if it returns at least
 * 5 bytes in response to SSL HELLO. The principle is that this is enough to
 * distinguish between an SSL server and a pure TCP relay. All other cases will
 * return -1. The function returns 0.
 */
int event_srv_chk_r(int fd)
{
	char reply[64];
	int len, result;
	struct task *t = fdtab[fd].owner;
	struct server *s = t->context;
	int skerr;
	socklen_t lskerr = sizeof(skerr);

	result = len = -1;

	getsockopt(fd, SOL_SOCKET, SO_ERROR, &skerr, &lskerr);
	if (!skerr) {
#ifndef MSG_NOSIGNAL
		len = recv(fd, reply, sizeof(reply), 0);
#else
		/* Warning! Linux returns EAGAIN on SO_ERROR if data are still available
		 * but the connection was closed on the remote end. Fortunately, recv still
		 * works correctly and we don't need to do the getsockopt() on linux.
		 */
		len = recv(fd, reply, sizeof(reply), MSG_NOSIGNAL);
#endif
		if (((s->proxy->options & PR_O_HTTP_CHK) &&
		     (len >= sizeof("HTTP/1.0 000")) &&
		    !memcmp(reply, "HTTP/1.", 7) &&
		    (reply[9] == '2' || reply[9] == '3')) /* 2xx or 3xx */
		    || ((s->proxy->options & PR_O_SSL3_CHK) && (len >= 5) &&
			(reply[0] == 0x15 || reply[0] == 0x16))) /* alert or handshake */
			result = 1;
	}

	if (result == -1)
		fdtab[fd].state = FD_STERROR;

	if (s->result != -1)
		s->result = result;

	FD_CLR(fd, StaticReadEvent);
	task_wakeup(&rq, t);
	return 0;
}

/*
 * manages a server health-check. Returns
 * the time the task accepts to wait, or TIME_ETERNITY for infinity.
 */
int process_chk(struct task *t)
{
	struct server *s = t->context;
	struct sockaddr_in sa;
	int fd;

	//fprintf(stderr, "process_chk: task=%p\n", t);

 new_chk:
	fd = s->curfd;
	if (fd < 0) {   /* no check currently running */
		//fprintf(stderr, "process_chk: 2\n");
		if (tv_cmp2_ms(&t->expire, &now) > 0) { /* not good time yet */
			task_queue(t);	/* restore t to its place in the task list */
			return tv_remain2(&now, &t->expire);
		}

		/* we don't send any health-checks when the proxy is stopped or when
		 * the server should not be checked.
		 */
		if (!(s->state & SRV_CHECKED) || s->proxy->state == PR_STSTOPPED) {
			while (tv_cmp2_ms(&t->expire, &now) <= 0)
				tv_delayfrom(&t->expire, &t->expire, s->inter);
			task_queue(t);	/* restore t to its place in the task list */
			return tv_remain2(&now, &t->expire);
		}

		/* we'll initiate a new check */
		s->result = 0; /* no result yet */
		if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) != -1) {
			if ((fd < global.maxsock) &&
			    (fcntl(fd, F_SETFL, O_NONBLOCK) != -1) &&
			    (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char *) &one, sizeof(one)) != -1)) {
				//fprintf(stderr, "process_chk: 3\n");

				/* we'll connect to the check port on the server */
				sa = s->addr;
				sa.sin_port = htons(s->check_port);

				/* allow specific binding :
				 * - server-specific at first
				 * - proxy-specific next
				 */
				if (s->state & SRV_BIND_SRC) {
					setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &one, sizeof(one));
					if (bind(fd, (struct sockaddr *)&s->source_addr, sizeof(s->source_addr)) == -1) {
						Alert("Cannot bind to source address before connect() for server %s/%s. Aborting.\n",
						      s->proxy->id, s->id);
						s->result = -1;
					}
				}
				else if (s->proxy->options & PR_O_BIND_SRC) {
					setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &one, sizeof(one));
					if (bind(fd, (struct sockaddr *)&s->proxy->source_addr, sizeof(s->proxy->source_addr)) == -1) {
						Alert("Cannot bind to source address before connect() for proxy %s. Aborting.\n",
						      s->proxy->id);
						s->result = -1;
					}
				}

				if (!s->result) {
					if ((connect(fd, (struct sockaddr *)&sa, sizeof(sa)) != -1) || (errno == EINPROGRESS)) {
						/* OK, connection in progress or established */
			
						//fprintf(stderr, "process_chk: 4\n");
			
						s->curfd = fd; /* that's how we know a test is in progress ;-) */
						fdtab[fd].owner = t;
						fdtab[fd].cb[DIR_RD].f = &event_srv_chk_r;
						fdtab[fd].cb[DIR_RD].b = NULL;
						fdtab[fd].cb[DIR_WR].f = &event_srv_chk_w;
						fdtab[fd].cb[DIR_WR].b = NULL;
						fdtab[fd].state = FD_STCONN; /* connection in progress */
						FD_SET(fd, StaticWriteEvent);  /* for connect status */
#ifdef DEBUG_FULL
						assert (!FD_ISSET(fd, StaticReadEvent));
#endif
						fd_insert(fd);
						/* FIXME: we allow up to <inter> for a connection to establish, but we should use another parameter */
						tv_delayfrom(&t->expire, &now, s->inter);
						task_queue(t);	/* restore t to its place in the task list */
						return tv_remain(&now, &t->expire);
					}
					else if (errno != EALREADY && errno != EISCONN && errno != EAGAIN) {
						s->result = -1;    /* a real error */
					}
				}
			}
			close(fd); /* socket creation error */
		}

		if (!s->result) { /* nothing done */
			//fprintf(stderr, "process_chk: 6\n");
			while (tv_cmp2_ms(&t->expire, &now) <= 0)
				tv_delayfrom(&t->expire, &t->expire, s->inter);
			goto new_chk; /* may be we should initialize a new check */
		}

		/* here, we have seen a failure */
		if (s->health > s->rise) {
			s->health--; /* still good */
			s->failed_checks++;
		}
		else
			set_server_down(s);

		//fprintf(stderr, "process_chk: 7\n");
		/* FIXME: we allow up to <inter> for a connection to establish, but we should use another parameter */
		while (tv_cmp2_ms(&t->expire, &now) <= 0)
			tv_delayfrom(&t->expire, &t->expire, s->inter);
		goto new_chk;
	}
	else {
		//fprintf(stderr, "process_chk: 8\n");
		/* there was a test running */
		if (s->result > 0) { /* good server detected */
			//fprintf(stderr, "process_chk: 9\n");
			s->health++; /* was bad, stays for a while */
			if (s->health >= s->rise) {
				s->state |= SRV_RUNNING;

				if (s->health == s->rise) {
					int xferred;

					recount_servers(s->proxy);
					recalc_server_map(s->proxy);

					/* check if we can handle some connections queued at the proxy. We
					 * will take as many as we can handle.
					 */
					for (xferred = 0; !s->maxconn || xferred < srv_dynamic_maxconn(s); xferred++) {
						struct session *sess;
						struct pendconn *p;

						p = pendconn_from_px(s->proxy);
						if (!p)
							break;
						p->sess->srv = s;
						sess = p->sess;
						pendconn_free(p);
						task_wakeup(&rq, sess->task);
					}

					sprintf(trash,
						"%sServer %s/%s is UP. %d active and %d backup servers online.%s"
						" %d sessions requeued, %d total in queue.\n",
						s->state & SRV_BACKUP ? "Backup " : "",
						s->proxy->id, s->id, s->proxy->srv_act, s->proxy->srv_bck,
						(s->proxy->srv_bck && !s->proxy->srv_act) ? " Running on backup." : "",
						xferred, s->nbpend);

					Warning("%s", trash);
					send_log(s->proxy, LOG_NOTICE, "%s", trash);
				}

				s->health = s->rise + s->fall - 1; /* OK now */
			}
			s->curfd = -1; /* no check running anymore */
			//FD_CLR(fd, StaticWriteEvent);
			fd_delete(fd);
			while (tv_cmp2_ms(&t->expire, &now) <= 0)
				tv_delayfrom(&t->expire, &t->expire, s->inter);
			goto new_chk;
		}
		else if (s->result < 0 || tv_cmp2_ms(&t->expire, &now) <= 0) {
			//fprintf(stderr, "process_chk: 10\n");
			/* failure or timeout detected */
			if (s->health > s->rise) {
				s->health--; /* still good */
				s->failed_checks++;
			}
			else
				set_server_down(s);
			s->curfd = -1;
			//FD_CLR(fd, StaticWriteEvent);
			fd_delete(fd);
			while (tv_cmp2_ms(&t->expire, &now) <= 0)
				tv_delayfrom(&t->expire, &t->expire, s->inter);
			goto new_chk;
		}
		/* if result is 0 and there's no timeout, we have to wait again */
	}
	//fprintf(stderr, "process_chk: 11\n");
	s->result = 0;
	task_queue(t);	/* restore t to its place in the task list */
	return tv_remain2(&now, &t->expire);
}


/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */