view src/core/ngx_syslog.c @ 7983:39501ce97e29

gRPC: generate error when response size is wrong. As long as the "Content-Length" header is given, we now make sure it exactly matches the size of the response. If it doesn't, the response is considered malformed and must not be forwarded (https://tools.ietf.org/html/rfc7540#section-8.1.2.6). While it is not really possible to "not forward" the response which is already being forwarded, we generate an error instead, which is the closest equivalent. Previous behaviour was to pass everything to the client, but this seems to be suboptimal and causes issues (ticket #1695). Also this directly contradicts HTTP/2 specification requirements. Note that the new behaviour for the gRPC proxy is more strict than that applied in other variants of proxying. This is intentional, as HTTP/2 specification requires us to do so, while in other types of proxying malformed responses from backends are well known and historically tolerated.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 06 Jul 2020 18:36:25 +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");
    }
}