blob: ff91ee3d01be8bda33fd0f336d581410975ae745 [file] [log] [blame]
/*
* Backend variables and 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 <stdlib.h>
#include <syslog.h>
#include <common/compat.h>
#include <common/config.h>
#include <common/time.h>
#include <types/buffers.h>
#include <types/global.h>
#include <types/polling.h>
#include <types/proxy.h>
#include <types/server.h>
#include <types/session.h>
#include <proto/backend.h>
#include <proto/fd.h>
#include <proto/log.h>
#include <proto/proto_http.h>
#include <proto/queue.h>
#include <proto/stream_sock.h>
#include <proto/task.h>
/*
* This function recounts the number of usable active and backup servers for
* proxy <p>. These numbers are returned into the p->srv_act and p->srv_bck.
* This function also recomputes the total active and backup weights.
*/
void recount_servers(struct proxy *px)
{
struct server *srv;
px->srv_act = 0; px->srv_bck = px->tot_wact = px->tot_wbck = 0;
for (srv = px->srv; srv != NULL; srv = srv->next) {
if (srv->state & SRV_RUNNING) {
if (srv->state & SRV_BACKUP) {
px->srv_bck++;
px->tot_wbck += srv->eweight + 1;
} else {
px->srv_act++;
px->tot_wact += srv->eweight + 1;
}
}
}
}
/* This function recomputes the server map for proxy px. It
* relies on px->tot_wact and px->tot_wbck, so it must be
* called after recount_servers(). It also expects px->srv_map
* to be initialized to the largest value needed.
*/
void recalc_server_map(struct proxy *px)
{
int o, tot, flag;
struct server *cur, *best;
if (px->srv_act) {
flag = SRV_RUNNING;
tot = px->tot_wact;
} else if (px->srv_bck) {
flag = SRV_RUNNING | SRV_BACKUP;
if (px->options & PR_O_USE_ALL_BK)
tot = px->tot_wbck;
else
tot = 1; /* the first server is enough */
} else {
px->srv_map_sz = 0;
return;
}
/* this algorithm gives priority to the first server, which means that
* it will respect the declaration order for equivalent weights, and
* that whatever the weights, the first server called will always be
* the first declard. This is an important asumption for the backup
* case, where we want the first server only.
*/
for (cur = px->srv; cur; cur = cur->next)
cur->wscore = 0;
for (o = 0; o < tot; o++) {
int max = 0;
best = NULL;
for (cur = px->srv; cur; cur = cur->next) {
if ((cur->state & (SRV_RUNNING | SRV_BACKUP)) == flag) {
int v;
/* If we are forced to return only one server, we don't want to
* go further, because we would return the wrong one due to
* divide overflow.
*/
if (tot == 1) {
best = cur;
break;
}
cur->wscore += cur->eweight + 1;
v = (cur->wscore + tot) / tot; /* result between 0 and 3 */
if (best == NULL || v > max) {
max = v;
best = cur;
}
}
}
px->srv_map[o] = best;
best->wscore -= tot;
}
px->srv_map_sz = tot;
}
/*
* This function marks the session as 'assigned' in direct or dispatch modes,
* or tries to assign one in balance mode, according to the algorithm. It does
* nothing if the session had already been assigned a server.
*
* It may return :
* SRV_STATUS_OK if everything is OK. s->srv will be valid.
* SRV_STATUS_NOSRV if no server is available. s->srv = NULL.
* SRV_STATUS_FULL if all servers are saturated. s->srv = NULL.
* SRV_STATUS_INTERNAL for other unrecoverable errors.
*
* Upon successful return, the session flag SN_ASSIGNED to indicate that it does
* not need to be called anymore. This usually means that s->srv can be trusted
* in balance and direct modes. This flag is not cleared, so it's to the caller
* to clear it if required (eg: redispatch).
*
*/
int assign_server(struct session *s)
{
#ifdef DEBUG_FULL
fprintf(stderr,"assign_server : s=%p\n",s);
#endif
if (s->pend_pos)
return SRV_STATUS_INTERNAL;
if (!(s->flags & SN_ASSIGNED)) {
if ((s->proxy->options & PR_O_BALANCE) && !(s->flags & SN_DIRECT)) {
if (!s->proxy->srv_act && !s->proxy->srv_bck)
return SRV_STATUS_NOSRV;
if (s->proxy->options & PR_O_BALANCE_RR) {
s->srv = get_server_rr_with_conns(s->proxy);
if (!s->srv)
return SRV_STATUS_FULL;
}
else if (s->proxy->options & PR_O_BALANCE_SH) {
int len;
if (s->cli_addr.ss_family == AF_INET)
len = 4;
else if (s->cli_addr.ss_family == AF_INET6)
len = 16;
else /* unknown IP family */
return SRV_STATUS_INTERNAL;
s->srv = get_server_sh(s->proxy,
(void *)&((struct sockaddr_in *)&s->cli_addr)->sin_addr,
len);
}
else /* unknown balancing algorithm */
return SRV_STATUS_INTERNAL;
}
s->flags |= SN_ASSIGNED;
}
return SRV_STATUS_OK;
}
/*
* This function assigns a server address to a session, and sets SN_ADDR_SET.
* The address is taken from the currently assigned server, or from the
* dispatch or transparent address.
*
* It may return :
* SRV_STATUS_OK if everything is OK.
* SRV_STATUS_INTERNAL for other unrecoverable errors.
*
* Upon successful return, the session flag SN_ADDR_SET is set. This flag is
* not cleared, so it's to the caller to clear it if required.
*
*/
int assign_server_address(struct session *s)
{
#ifdef DEBUG_FULL
fprintf(stderr,"assign_server_address : s=%p\n",s);
#endif
if (s->flags & SN_DIRECT || s->proxy->options & PR_O_BALANCE) {
/* A server is necessarily known for this session */
if (!(s->flags & SN_ASSIGNED))
return SRV_STATUS_INTERNAL;
s->srv_addr = s->srv->addr;
/* if this server remaps proxied ports, we'll use
* the port the client connected to with an offset. */
if (s->srv->state & SRV_MAPPORTS) {
struct sockaddr_in sockname;
socklen_t namelen = sizeof(sockname);
if (!(s->proxy->options & PR_O_TRANSP) ||
get_original_dst(s->cli_fd, (struct sockaddr_in *)&sockname, &namelen) == -1)
getsockname(s->cli_fd, (struct sockaddr *)&sockname, &namelen);
s->srv_addr.sin_port = htons(ntohs(s->srv_addr.sin_port) + ntohs(sockname.sin_port));
}
}
else if (*(int *)&s->proxy->dispatch_addr.sin_addr) {
/* connect to the defined dispatch addr */
s->srv_addr = s->proxy->dispatch_addr;
}
else if (s->proxy->options & PR_O_TRANSP) {
/* in transparent mode, use the original dest addr if no dispatch specified */
socklen_t salen = sizeof(s->srv_addr);
if (get_original_dst(s->cli_fd, &s->srv_addr, &salen) == -1) {
qfprintf(stderr, "Cannot get original server address.\n");
return SRV_STATUS_INTERNAL;
}
}
s->flags |= SN_ADDR_SET;
return SRV_STATUS_OK;
}
/* This function assigns a server to session <s> if required, and can add the
* connection to either the assigned server's queue or to the proxy's queue.
*
* Returns :
*
* SRV_STATUS_OK if everything is OK.
* SRV_STATUS_NOSRV if no server is available. s->srv = NULL.
* SRV_STATUS_QUEUED if the connection has been queued.
* SRV_STATUS_FULL if the server(s) is/are saturated and the
* connection could not be queued.
* SRV_STATUS_INTERNAL for other unrecoverable errors.
*
*/
int assign_server_and_queue(struct session *s)
{
struct pendconn *p;
int err;
if (s->pend_pos)
return SRV_STATUS_INTERNAL;
if (s->flags & SN_ASSIGNED) {
/* a server does not need to be assigned, perhaps because we're in
* direct mode, or in dispatch or transparent modes where the server
* is not needed.
*/
if (s->srv &&
s->srv->maxconn && s->srv->cur_sess >= srv_dynamic_maxconn(s->srv)) {
p = pendconn_add(s);
if (p)
return SRV_STATUS_QUEUED;
else
return SRV_STATUS_FULL;
}
return SRV_STATUS_OK;
}
/* a server needs to be assigned */
err = assign_server(s);
switch (err) {
case SRV_STATUS_OK:
/* in balance mode, we might have servers with connection limits */
if (s->srv &&
s->srv->maxconn && s->srv->cur_sess >= srv_dynamic_maxconn(s->srv)) {
p = pendconn_add(s);
if (p)
return SRV_STATUS_QUEUED;
else
return SRV_STATUS_FULL;
}
return SRV_STATUS_OK;
case SRV_STATUS_FULL:
/* queue this session into the proxy's queue */
p = pendconn_add(s);
if (p)
return SRV_STATUS_QUEUED;
else
return SRV_STATUS_FULL;
case SRV_STATUS_NOSRV:
case SRV_STATUS_INTERNAL:
return err;
default:
return SRV_STATUS_INTERNAL;
}
}
/*
* This function initiates a connection to the server assigned to this session
* (s->srv, s->srv_addr). It will assign a server if none is assigned yet.
* It can return one of :
* - SN_ERR_NONE if everything's OK
* - SN_ERR_SRVTO if there are no more servers
* - SN_ERR_SRVCL if the connection was refused by the server
* - SN_ERR_PRXCOND if the connection has been limited by the proxy (maxconn)
* - SN_ERR_RESOURCE if a system resource is lacking (eg: fd limits, ports, ...)
* - SN_ERR_INTERNAL for any other purely internal errors
* Additionnally, in the case of SN_ERR_RESOURCE, an emergency log will be emitted.
*/
int connect_server(struct session *s)
{
int fd, err;
if (!(s->flags & SN_ADDR_SET)) {
err = assign_server_address(s);
if (err != SRV_STATUS_OK)
return SN_ERR_INTERNAL;
}
if ((fd = s->srv_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
qfprintf(stderr, "Cannot get a server socket.\n");
if (errno == ENFILE)
send_log(s->proxy, LOG_EMERG,
"Proxy %s reached system FD limit at %d. Please check system tunables.\n",
s->proxy->id, maxfd);
else if (errno == EMFILE)
send_log(s->proxy, LOG_EMERG,
"Proxy %s reached process FD limit at %d. Please check 'ulimit-n' and restart.\n",
s->proxy->id, maxfd);
else if (errno == ENOBUFS || errno == ENOMEM)
send_log(s->proxy, LOG_EMERG,
"Proxy %s reached system memory limit at %d sockets. Please check system tunables.\n",
s->proxy->id, maxfd);
/* this is a resource error */
return SN_ERR_RESOURCE;
}
if (fd >= global.maxsock) {
/* do not log anything there, it's a normal condition when this option
* is used to serialize connections to a server !
*/
Alert("socket(): not enough free sockets. Raise -n argument. Giving up.\n");
close(fd);
return SN_ERR_PRXCOND; /* it is a configuration limit */
}
if ((fcntl(fd, F_SETFL, O_NONBLOCK)==-1) ||
(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char *) &one, sizeof(one)) == -1)) {
qfprintf(stderr,"Cannot set client socket to non blocking mode.\n");
close(fd);
return SN_ERR_INTERNAL;
}
if (s->proxy->options & PR_O_TCP_SRV_KA)
setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (char *) &one, sizeof(one));
/* allow specific binding :
* - server-specific at first
* - proxy-specific next
*/
if (s->srv != NULL && s->srv->state & SRV_BIND_SRC) {
setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &one, sizeof(one));
if (bind(fd, (struct sockaddr *)&s->srv->source_addr, sizeof(s->srv->source_addr)) == -1) {
Alert("Cannot bind to source address before connect() for server %s/%s. Aborting.\n",
s->proxy->id, s->srv->id);
close(fd);
send_log(s->proxy, LOG_EMERG,
"Cannot bind to source address before connect() for server %s/%s.\n",
s->proxy->id, s->srv->id);
return SN_ERR_RESOURCE;
}
}
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);
close(fd);
send_log(s->proxy, LOG_EMERG,
"Cannot bind to source address before connect() for server %s/%s.\n",
s->proxy->id, s->srv->id);
return SN_ERR_RESOURCE;
}
}
if ((connect(fd, (struct sockaddr *)&s->srv_addr, sizeof(s->srv_addr)) == -1) &&
(errno != EINPROGRESS) && (errno != EALREADY) && (errno != EISCONN)) {
if (errno == EAGAIN || errno == EADDRINUSE) {
char *msg;
if (errno == EAGAIN) /* no free ports left, try again later */
msg = "no free ports";
else
msg = "local address already in use";
qfprintf(stderr,"Cannot connect: %s.\n",msg);
close(fd);
send_log(s->proxy, LOG_EMERG,
"Connect() failed for server %s/%s: %s.\n",
s->proxy->id, s->srv->id, msg);
return SN_ERR_RESOURCE;
} else if (errno == ETIMEDOUT) {
//qfprintf(stderr,"Connect(): ETIMEDOUT");
close(fd);
return SN_ERR_SRVTO;
} else {
// (errno == ECONNREFUSED || errno == ENETUNREACH || errno == EACCES || errno == EPERM)
//qfprintf(stderr,"Connect(): %d", errno);
close(fd);
return SN_ERR_SRVCL;
}
}
fdtab[fd].owner = s->task;
fdtab[fd].read = &event_srv_read;
fdtab[fd].write = &event_srv_write;
fdtab[fd].state = FD_STCONN; /* connection in progress */
FD_SET(fd, StaticWriteEvent); /* for connect status */
#if defined(DEBUG_FULL) && defined(ENABLE_EPOLL)
if (PrevReadEvent) {
assert(!(FD_ISSET(fd, PrevReadEvent)));
assert(!(FD_ISSET(fd, PrevWriteEvent)));
}
#endif
fd_insert(fd);
if (s->srv) {
s->srv->cur_sess++;
if (s->srv->cur_sess > s->srv->cur_sess_max)
s->srv->cur_sess_max = s->srv->cur_sess;
}
if (s->proxy->contimeout)
tv_delayfrom(&s->cnexpire, &now, s->proxy->contimeout);
else
tv_eternity(&s->cnexpire);
return SN_ERR_NONE; /* connection is OK */
}
/*
* This function checks the retry count during the connect() job.
* It updates the session's srv_state and retries, so that the caller knows
* what it has to do. It uses the last connection error to set the log when
* it expires. It returns 1 when it has expired, and 0 otherwise.
*/
int srv_count_retry_down(struct session *t, int conn_err)
{
/* we are in front of a retryable error */
t->conn_retries--;
if (t->conn_retries < 0) {
/* if not retryable anymore, let's abort */
tv_eternity(&t->cnexpire);
srv_close_with_err(t, conn_err, SN_FINST_C,
503, t->proxy->errmsg.len503, t->proxy->errmsg.msg503);
if (t->srv)
t->srv->failed_conns++;
t->proxy->failed_conns++;
/* We used to have a free connection slot. Since we'll never use it,
* we have to inform the server that it may be used by another session.
*/
if (may_dequeue_tasks(t->srv, t->proxy))
task_wakeup(&rq, t->srv->queue_mgt);
return 1;
}
return 0;
}
/*
* This function performs the retryable part of the connect() job.
* It updates the session's srv_state and retries, so that the caller knows
* what it has to do. It returns 1 when it breaks out of the loop, or 0 if
* it needs to redispatch.
*/
int srv_retryable_connect(struct session *t)
{
int conn_err;
/* This loop ensures that we stop before the last retry in case of a
* redispatchable server.
*/
do {
/* initiate a connection to the server */
conn_err = connect_server(t);
switch (conn_err) {
case SN_ERR_NONE:
//fprintf(stderr,"0: c=%d, s=%d\n", c, s);
t->srv_state = SV_STCONN;
return 1;
case SN_ERR_INTERNAL:
tv_eternity(&t->cnexpire);
srv_close_with_err(t, SN_ERR_INTERNAL, SN_FINST_C,
500, t->proxy->errmsg.len500, t->proxy->errmsg.msg500);
if (t->srv)
t->srv->failed_conns++;
t->proxy->failed_conns++;
/* release other sessions waiting for this server */
if (may_dequeue_tasks(t->srv, t->proxy))
task_wakeup(&rq, t->srv->queue_mgt);
return 1;
}
/* ensure that we have enough retries left */
if (srv_count_retry_down(t, conn_err)) {
/* let's try to offer this slot to anybody */
if (may_dequeue_tasks(t->srv, t->proxy))
task_wakeup(&rq, t->srv->queue_mgt);
return 1;
}
} while (t->srv == NULL || t->conn_retries > 0 || !(t->proxy->options & PR_O_REDISP));
/* We're on our last chance, and the REDISP option was specified.
* We will ignore cookie and force to balance or use the dispatcher.
*/
/* let's try to offer this slot to anybody */
if (may_dequeue_tasks(t->srv, t->proxy))
task_wakeup(&rq, t->srv->queue_mgt);
if (t->srv)
t->srv->failed_conns++;
t->proxy->failed_conns++;
t->flags &= ~(SN_DIRECT | SN_ASSIGNED | SN_ADDR_SET);
t->srv = NULL; /* it's left to the dispatcher to choose a server */
if ((t->flags & SN_CK_MASK) == SN_CK_VALID) {
t->flags &= ~SN_CK_MASK;
t->flags |= SN_CK_DOWN;
}
return 0;
}
/* This function performs the "redispatch" part of a connection attempt. It
* will assign a server if required, queue the connection if required, and
* handle errors that might arise at this level. It can change the server
* state. It will return 1 if it encounters an error, switches the server
* state, or has to queue a connection. Otherwise, it will return 0 indicating
* that the connection is ready to use.
*/
int srv_redispatch_connect(struct session *t)
{
int conn_err;
/* We know that we don't have any connection pending, so we will
* try to get a new one, and wait in this state if it's queued
*/
conn_err = assign_server_and_queue(t);
switch (conn_err) {
case SRV_STATUS_OK:
break;
case SRV_STATUS_NOSRV:
/* note: it is guaranteed that t->srv == NULL here */
tv_eternity(&t->cnexpire);
srv_close_with_err(t, SN_ERR_SRVTO, SN_FINST_C,
503, t->proxy->errmsg.len503, t->proxy->errmsg.msg503);
if (t->srv)
t->srv->failed_conns++;
t->proxy->failed_conns++;
return 1;
case SRV_STATUS_QUEUED:
/* FIXME-20060503 : we should use the queue timeout instead */
if (t->proxy->contimeout)
tv_delayfrom(&t->cnexpire, &now, t->proxy->contimeout);
else
tv_eternity(&t->cnexpire);
t->srv_state = SV_STIDLE;
/* do nothing else and do not wake any other session up */
return 1;
case SRV_STATUS_FULL:
case SRV_STATUS_INTERNAL:
default:
tv_eternity(&t->cnexpire);
srv_close_with_err(t, SN_ERR_INTERNAL, SN_FINST_C,
500, t->proxy->errmsg.len500, t->proxy->errmsg.msg500);
if (t->srv)
t->srv->failed_conns++;
t->proxy->failed_conns++;
/* release other sessions waiting for this server */
if (may_dequeue_tasks(t->srv, t->proxy))
task_wakeup(&rq, t->srv->queue_mgt);
return 1;
}
/* if we get here, it's because we got SRV_STATUS_OK, which also
* means that the connection has not been queued.
*/
return 0;
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/