view src/core/ngx_syslog.c @ 8743:5d09596909c6 stable-1.20

Upstream: fixed timeouts with gRPC, SSL and select (ticket #2229). With SSL it is possible that an established connection is ready for reading after the handshake. Further, events might be already disabled in case of level-triggered event methods. If this happens and ngx_http_upstream_send_request() blocks waiting for some data from the upstream, such as flow control in case of gRPC, the connection will time out due to no read events on the upstream connection. Fix is to explicitly check the c->read->ready flag if sending request blocks and post a read event if it is set. Note that while it is possible to modify ngx_ssl_handshake() to keep read events active, this won't completely resolve the issue, since there can be data already received during the SSL handshake (see 573bd30e46b4).
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 20 Aug 2021 03:53:56 +0300
parents 7f9935f07fe9
children 29adacffdefa
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


#define NGX_SYSLOG_MAX_STR                                                    \
    NGX_MAX_ERROR_STR + sizeof("<255>Jan 01 00:00:00 ") - 1                   \
    + (NGX_MAXHOSTNAMELEN - 1) + 1 /* space */                                \
    + 32 /* tag */ + 2 /* colon, space */


static char *ngx_syslog_parse_args(ngx_conf_t *cf, ngx_syslog_peer_t *peer);
static ngx_int_t ngx_syslog_init_peer(ngx_syslog_peer_t *peer);
static void ngx_syslog_cleanup(void *data);


static char  *facilities[] = {
    "kern", "user", "mail", "daemon", "auth", "intern", "lpr", "news", "uucp",
    "clock", "authpriv", "ftp", "ntp", "audit", "alert", "cron", "local0",
    "local1", "local2", "local3", "local4", "local5", "local6", "local7",
    NULL
};

/* note 'error/warn' like in nginx.conf, not 'err/warning' */
static char  *severities[] = {
    "emerg", "alert", "crit", "error", "warn", "notice", "info", "debug", NULL
};

static ngx_log_t    ngx_syslog_dummy_log;
static ngx_event_t  ngx_syslog_dummy_event;


char *
ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
{
    ngx_pool_cleanup_t  *cln;

    peer->facility = NGX_CONF_UNSET_UINT;
    peer->severity = NGX_CONF_UNSET_UINT;

    if (ngx_syslog_parse_args(cf, peer) != NGX_CONF_OK) {
        return NGX_CONF_ERROR;
    }

    if (peer->server.sockaddr == NULL) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "no syslog server specified");
        return NGX_CONF_ERROR;
    }

    if (peer->facility == NGX_CONF_UNSET_UINT) {
        peer->facility = 23; /* local7 */
    }

    if (peer->severity == NGX_CONF_UNSET_UINT) {
        peer->severity = 6; /* info */
    }

    if (peer->tag.data == NULL) {
        ngx_str_set(&peer->tag, "nginx");
    }

    peer->conn.fd = (ngx_socket_t) -1;

    peer->conn.read = &ngx_syslog_dummy_event;
    peer->conn.write = &ngx_syslog_dummy_event;

    ngx_syslog_dummy_event.log = &ngx_syslog_dummy_log;

    cln = ngx_pool_cleanup_add(cf->pool, 0);
    if (cln == NULL) {
        return NGX_CONF_ERROR;
    }

    cln->data = peer;
    cln->handler = ngx_syslog_cleanup;

    return NGX_CONF_OK;
}


static char *
ngx_syslog_parse_args(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
{
    u_char      *p, *comma, c;
    size_t       len;
    ngx_str_t   *value;
    ngx_url_t    u;
    ngx_uint_t   i;

    value = cf->args->elts;

    p = value[1].data + sizeof("syslog:") - 1;

    for ( ;; ) {
        comma = (u_char *) ngx_strchr(p, ',');

        if (comma != NULL) {
            len = comma - p;
            *comma = '\0';

        } else {
            len = value[1].data + value[1].len - p;
        }

        if (ngx_strncmp(p, "server=", 7) == 0) {

            if (peer->server.sockaddr != NULL) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "duplicate syslog \"server\"");
                return NGX_CONF_ERROR;
            }

            ngx_memzero(&u, sizeof(ngx_url_t));

            u.url.data = p + 7;
            u.url.len = len - 7;
            u.default_port = 514;

            if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
                if (u.err) {
                    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                       "%s in syslog server \"%V\"",
                                       u.err, &u.url);
                }

                return NGX_CONF_ERROR;
            }

            peer->server = u.addrs[0];

        } else if (ngx_strncmp(p, "facility=", 9) == 0) {

            if (peer->facility != NGX_CONF_UNSET_UINT) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "duplicate syslog \"facility\"");
                return NGX_CONF_ERROR;
            }

            for (i = 0; facilities[i] != NULL; i++) {

                if (ngx_strcmp(p + 9, facilities[i]) == 0) {
                    peer->facility = i;
                    goto next;
                }
            }

            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "unknown syslog facility \"%s\"", p + 9);
            return NGX_CONF_ERROR;

        } else if (ngx_strncmp(p, "severity=", 9) == 0) {

            if (peer->severity != NGX_CONF_UNSET_UINT) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "duplicate syslog \"severity\"");
                return NGX_CONF_ERROR;
            }

            for (i = 0; severities[i] != NULL; i++) {

                if (ngx_strcmp(p + 9, severities[i]) == 0) {
                    peer->severity = i;
                    goto next;
                }
            }

            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "unknown syslog severity \"%s\"", p + 9);
            return NGX_CONF_ERROR;

        } else if (ngx_strncmp(p, "tag=", 4) == 0) {

            if (peer->tag.data != NULL) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "duplicate syslog \"tag\"");
                return NGX_CONF_ERROR;
            }

            /*
             * RFC 3164: the TAG is a string of ABNF alphanumeric characters
             * that MUST NOT exceed 32 characters.
             */
            if (len - 4 > 32) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "syslog tag length exceeds 32");
                return NGX_CONF_ERROR;
            }

            for (i = 4; i < len; i++) {
                c = ngx_tolower(p[i]);

                if (c < '0' || (c > '9' && c < 'a' && c != '_') || c > 'z') {
                    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                       "syslog \"tag\" only allows "
                                       "alphanumeric characters "
                                       "and underscore");
                    return NGX_CONF_ERROR;
                }
            }

            peer->tag.data = p + 4;
            peer->tag.len = len - 4;

        } else if (len == 10 && ngx_strncmp(p, "nohostname", 10) == 0) {
            peer->nohostname = 1;

        } else {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "unknown syslog parameter \"%s\"", p);
            return NGX_CONF_ERROR;
        }

    next:

        if (comma == NULL) {
            break;
        }

        p = comma + 1;
    }

    return NGX_CONF_OK;
}


u_char *
ngx_syslog_add_header(ngx_syslog_peer_t *peer, u_char *buf)
{
    ngx_uint_t  pri;

    pri = peer->facility * 8 + peer->severity;

    if (peer->nohostname) {
        return ngx_sprintf(buf, "<%ui>%V %V: ", pri, &ngx_cached_syslog_time,
                           &peer->tag);
    }

    return ngx_sprintf(buf, "<%ui>%V %V %V: ", pri, &ngx_cached_syslog_time,
                       &ngx_cycle->hostname, &peer->tag);
}


void
ngx_syslog_writer(ngx_log_t *log, ngx_uint_t level, u_char *buf,
    size_t len)
{
    u_char             *p, msg[NGX_SYSLOG_MAX_STR];
    ngx_uint_t          head_len;
    ngx_syslog_peer_t  *peer;

    peer = log->wdata;

    if (peer->busy) {
        return;
    }

    peer->busy = 1;
    peer->severity = level - 1;

    p = ngx_syslog_add_header(peer, msg);
    head_len = p - msg;

    len -= NGX_LINEFEED_SIZE;

    if (len > NGX_SYSLOG_MAX_STR - head_len) {
        len = NGX_SYSLOG_MAX_STR - head_len;
    }

    p = ngx_snprintf(p, len, "%s", buf);

    (void) ngx_syslog_send(peer, msg, p - msg);

    peer->busy = 0;
}


ssize_t
ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len)
{
    ssize_t  n;

    if (peer->conn.fd == (ngx_socket_t) -1) {
        if (ngx_syslog_init_peer(peer) != NGX_OK) {
            return NGX_ERROR;
        }
    }

    /* log syslog socket events with valid log */
    peer->conn.log = ngx_cycle->log;

    if (ngx_send) {
        n = ngx_send(&peer->conn, buf, len);

    } else {
        /* event module has not yet set ngx_io */
        n = ngx_os_io.send(&peer->conn, buf, len);
    }

    if (n == NGX_ERROR) {

        if (ngx_close_socket(peer->conn.fd) == -1) {
            ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                          ngx_close_socket_n " failed");
        }

        peer->conn.fd = (ngx_socket_t) -1;
    }

    return n;
}


static ngx_int_t
ngx_syslog_init_peer(ngx_syslog_peer_t *peer)
{
    ngx_socket_t  fd;

    fd = ngx_socket(peer->server.sockaddr->sa_family, SOCK_DGRAM, 0);
    if (fd == (ngx_socket_t) -1) {
        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                      ngx_socket_n " failed");
        return NGX_ERROR;
    }

    if (ngx_nonblocking(fd) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                      ngx_nonblocking_n " failed");
        goto failed;
    }

    if (connect(fd, peer->server.sockaddr, peer->server.socklen) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                      "connect() failed");
        goto failed;
    }

    peer->conn.fd = fd;

    /* UDP sockets are always ready to write */
    peer->conn.write->ready = 1;

    return NGX_OK;

failed:

    if (ngx_close_socket(fd) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                      ngx_close_socket_n " failed");
    }

    return NGX_ERROR;
}


static void
ngx_syslog_cleanup(void *data)
{
    ngx_syslog_peer_t  *peer = data;

    /* prevents further use of this peer */
    peer->busy = 1;

    if (peer->conn.fd == (ngx_socket_t) -1) {
        return;
    }

    if (ngx_close_socket(peer->conn.fd) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
                      ngx_close_socket_n " failed");
    }
}