Mercurial > hg > nginx-quic
view src/stream/ngx_stream_core_module.c @ 7054:e02555553d0b
Range filter: protect from total size overflows.
The overflow can be used to circumvent the restriction on total size of
ranges introduced in c2a91088b0c0 (1.1.2). Additionally, overflow
allows producing ranges with negative start (such ranges can be created
by using a suffix, "bytes=-100"; normally this results in 200 due to
the total size check). These can result in the following errors in logs:
[crit] ... pread() ... failed (22: Invalid argument)
[alert] ... sendfile() failed (22: Invalid argument)
When using cache, it can be also used to reveal cache file header.
It is believed that there are no other negative effects, at least with
standard nginx modules.
In theory, this can also result in memory disclosure and/or segmentation
faults if multiple ranges are allowed, and the response is returned in a
single in-memory buffer. This never happens with standard nginx modules
though, as well as known 3rd party modules.
Fix is to properly protect from possible overflow when incrementing size.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Tue, 11 Jul 2017 16:06:23 +0300 |
parents | ed1101bbf19f |
children | 7f955d3b9a0d |
line wrap: on
line source
/* * Copyright (C) Roman Arutyunyan * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_stream.h> static ngx_int_t ngx_stream_core_preconfiguration(ngx_conf_t *cf); static void *ngx_stream_core_create_main_conf(ngx_conf_t *cf); static char *ngx_stream_core_init_main_conf(ngx_conf_t *cf, void *conf); static void *ngx_stream_core_create_srv_conf(ngx_conf_t *cf); static char *ngx_stream_core_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child); static char *ngx_stream_core_error_log(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_stream_core_server(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_stream_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_stream_core_resolver(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_stream_core_commands[] = { { ngx_string("variables_hash_max_size"), NGX_STREAM_MAIN_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, NGX_STREAM_MAIN_CONF_OFFSET, offsetof(ngx_stream_core_main_conf_t, variables_hash_max_size), NULL }, { ngx_string("variables_hash_bucket_size"), NGX_STREAM_MAIN_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, NGX_STREAM_MAIN_CONF_OFFSET, offsetof(ngx_stream_core_main_conf_t, variables_hash_bucket_size), NULL }, { ngx_string("server"), NGX_STREAM_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_NOARGS, ngx_stream_core_server, 0, 0, NULL }, { ngx_string("listen"), NGX_STREAM_SRV_CONF|NGX_CONF_1MORE, ngx_stream_core_listen, NGX_STREAM_SRV_CONF_OFFSET, 0, NULL }, { ngx_string("error_log"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_1MORE, ngx_stream_core_error_log, NGX_STREAM_SRV_CONF_OFFSET, 0, NULL }, { ngx_string("resolver"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_1MORE, ngx_stream_core_resolver, NGX_STREAM_SRV_CONF_OFFSET, 0, NULL }, { ngx_string("resolver_timeout"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1, ngx_conf_set_msec_slot, NGX_STREAM_SRV_CONF_OFFSET, offsetof(ngx_stream_core_srv_conf_t, resolver_timeout), NULL }, { ngx_string("proxy_protocol_timeout"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1, ngx_conf_set_msec_slot, NGX_STREAM_SRV_CONF_OFFSET, offsetof(ngx_stream_core_srv_conf_t, proxy_protocol_timeout), NULL }, { ngx_string("tcp_nodelay"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG, ngx_conf_set_flag_slot, NGX_STREAM_SRV_CONF_OFFSET, offsetof(ngx_stream_core_srv_conf_t, tcp_nodelay), NULL }, { ngx_string("preread_buffer_size"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1, ngx_conf_set_size_slot, NGX_STREAM_SRV_CONF_OFFSET, offsetof(ngx_stream_core_srv_conf_t, preread_buffer_size), NULL }, { ngx_string("preread_timeout"), NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1, ngx_conf_set_msec_slot, NGX_STREAM_SRV_CONF_OFFSET, offsetof(ngx_stream_core_srv_conf_t, preread_timeout), NULL }, ngx_null_command }; static ngx_stream_module_t ngx_stream_core_module_ctx = { ngx_stream_core_preconfiguration, /* preconfiguration */ NULL, /* postconfiguration */ ngx_stream_core_create_main_conf, /* create main configuration */ ngx_stream_core_init_main_conf, /* init main configuration */ ngx_stream_core_create_srv_conf, /* create server configuration */ ngx_stream_core_merge_srv_conf /* merge server configuration */ }; ngx_module_t ngx_stream_core_module = { NGX_MODULE_V1, &ngx_stream_core_module_ctx, /* module context */ ngx_stream_core_commands, /* module directives */ NGX_STREAM_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; void ngx_stream_core_run_phases(ngx_stream_session_t *s) { ngx_int_t rc; ngx_stream_phase_handler_t *ph; ngx_stream_core_main_conf_t *cmcf; cmcf = ngx_stream_get_module_main_conf(s, ngx_stream_core_module); ph = cmcf->phase_engine.handlers; while (ph[s->phase_handler].checker) { rc = ph[s->phase_handler].checker(s, &ph[s->phase_handler]); if (rc == NGX_OK) { return; } } } ngx_int_t ngx_stream_core_generic_phase(ngx_stream_session_t *s, ngx_stream_phase_handler_t *ph) { ngx_int_t rc; /* * generic phase checker, * used by all phases, except for preread and content */ ngx_log_debug1(NGX_LOG_DEBUG_STREAM, s->connection->log, 0, "generic phase: %ui", s->phase_handler); rc = ph->handler(s); if (rc == NGX_OK) { s->phase_handler = ph->next; return NGX_AGAIN; } if (rc == NGX_DECLINED) { s->phase_handler++; return NGX_AGAIN; } if (rc == NGX_AGAIN || rc == NGX_DONE) { return NGX_OK; } if (rc == NGX_ERROR) { rc = NGX_STREAM_INTERNAL_SERVER_ERROR; } ngx_stream_finalize_session(s, rc); return NGX_OK; } ngx_int_t ngx_stream_core_preread_phase(ngx_stream_session_t *s, ngx_stream_phase_handler_t *ph) { size_t size; ssize_t n; ngx_int_t rc; ngx_connection_t *c; ngx_stream_core_srv_conf_t *cscf; c = s->connection; c->log->action = "prereading client data"; cscf = ngx_stream_get_module_srv_conf(s, ngx_stream_core_module); if (c->read->timedout) { rc = NGX_STREAM_OK; } else if (c->read->timer_set) { rc = NGX_AGAIN; } else { rc = ph->handler(s); } while (rc == NGX_AGAIN) { if (c->buffer == NULL) { c->buffer = ngx_create_temp_buf(c->pool, cscf->preread_buffer_size); if (c->buffer == NULL) { rc = NGX_ERROR; break; } } size = c->buffer->end - c->buffer->last; if (size == 0) { ngx_log_error(NGX_LOG_ERR, c->log, 0, "preread buffer full"); rc = NGX_STREAM_BAD_REQUEST; break; } if (c->read->eof) { rc = NGX_STREAM_OK; break; } if (!c->read->ready) { if (ngx_handle_read_event(c->read, 0) != NGX_OK) { rc = NGX_ERROR; break; } if (!c->read->timer_set) { ngx_add_timer(c->read, cscf->preread_timeout); } c->read->handler = ngx_stream_session_handler; return NGX_OK; } n = c->recv(c, c->buffer->last, size); if (n == NGX_ERROR) { rc = NGX_STREAM_OK; break; } if (n > 0) { c->buffer->last += n; } rc = ph->handler(s); } if (c->read->timer_set) { ngx_del_timer(c->read); } if (rc == NGX_OK) { s->phase_handler = ph->next; return NGX_AGAIN; } if (rc == NGX_DECLINED) { s->phase_handler++; return NGX_AGAIN; } if (rc == NGX_DONE) { return NGX_OK; } if (rc == NGX_ERROR) { rc = NGX_STREAM_INTERNAL_SERVER_ERROR; } ngx_stream_finalize_session(s, rc); return NGX_OK; } ngx_int_t ngx_stream_core_content_phase(ngx_stream_session_t *s, ngx_stream_phase_handler_t *ph) { ngx_connection_t *c; ngx_stream_core_srv_conf_t *cscf; c = s->connection; c->log->action = NULL; cscf = ngx_stream_get_module_srv_conf(s, ngx_stream_core_module); if (c->type == SOCK_STREAM && cscf->tcp_nodelay && ngx_tcp_nodelay(c) != NGX_OK) { ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR); return NGX_OK; } cscf->handler(s); return NGX_OK; } static ngx_int_t ngx_stream_core_preconfiguration(ngx_conf_t *cf) { return ngx_stream_variables_add_core_vars(cf); } static void * ngx_stream_core_create_main_conf(ngx_conf_t *cf) { ngx_stream_core_main_conf_t *cmcf; cmcf = ngx_pcalloc(cf->pool, sizeof(ngx_stream_core_main_conf_t)); if (cmcf == NULL) { return NULL; } if (ngx_array_init(&cmcf->servers, cf->pool, 4, sizeof(ngx_stream_core_srv_conf_t *)) != NGX_OK) { return NULL; } if (ngx_array_init(&cmcf->listen, cf->pool, 4, sizeof(ngx_stream_listen_t)) != NGX_OK) { return NULL; } cmcf->variables_hash_max_size = NGX_CONF_UNSET_UINT; cmcf->variables_hash_bucket_size = NGX_CONF_UNSET_UINT; return cmcf; } static char * ngx_stream_core_init_main_conf(ngx_conf_t *cf, void *conf) { ngx_stream_core_main_conf_t *cmcf = conf; ngx_conf_init_uint_value(cmcf->variables_hash_max_size, 1024); ngx_conf_init_uint_value(cmcf->variables_hash_bucket_size, 64); cmcf->variables_hash_bucket_size = ngx_align(cmcf->variables_hash_bucket_size, ngx_cacheline_size); if (cmcf->ncaptures) { cmcf->ncaptures = (cmcf->ncaptures + 1) * 3; } return NGX_CONF_OK; } static void * ngx_stream_core_create_srv_conf(ngx_conf_t *cf) { ngx_stream_core_srv_conf_t *cscf; cscf = ngx_pcalloc(cf->pool, sizeof(ngx_stream_core_srv_conf_t)); if (cscf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * cscf->handler = NULL; * cscf->error_log = NULL; */ cscf->file_name = cf->conf_file->file.name.data; cscf->line = cf->conf_file->line; cscf->resolver_timeout = NGX_CONF_UNSET_MSEC; cscf->proxy_protocol_timeout = NGX_CONF_UNSET_MSEC; cscf->tcp_nodelay = NGX_CONF_UNSET; cscf->preread_buffer_size = NGX_CONF_UNSET_SIZE; cscf->preread_timeout = NGX_CONF_UNSET_MSEC; return cscf; } static char * ngx_stream_core_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_stream_core_srv_conf_t *prev = parent; ngx_stream_core_srv_conf_t *conf = child; ngx_conf_merge_msec_value(conf->resolver_timeout, prev->resolver_timeout, 30000); if (conf->resolver == NULL) { if (prev->resolver == NULL) { /* * create dummy resolver in stream {} context * to inherit it in all servers */ prev->resolver = ngx_resolver_create(cf, NULL, 0); if (prev->resolver == NULL) { return NGX_CONF_ERROR; } } conf->resolver = prev->resolver; } if (conf->handler == NULL) { ngx_log_error(NGX_LOG_EMERG, cf->log, 0, "no handler for server in %s:%ui", conf->file_name, conf->line); return NGX_CONF_ERROR; } if (conf->error_log == NULL) { if (prev->error_log) { conf->error_log = prev->error_log; } else { conf->error_log = &cf->cycle->new_log; } } ngx_conf_merge_msec_value(conf->proxy_protocol_timeout, prev->proxy_protocol_timeout, 30000); ngx_conf_merge_value(conf->tcp_nodelay, prev->tcp_nodelay, 1); ngx_conf_merge_size_value(conf->preread_buffer_size, prev->preread_buffer_size, 16384); ngx_conf_merge_msec_value(conf->preread_timeout, prev->preread_timeout, 30000); return NGX_CONF_OK; } static char * ngx_stream_core_error_log(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_stream_core_srv_conf_t *cscf = conf; return ngx_log_set_log(cf, &cscf->error_log); } static char * ngx_stream_core_server(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { char *rv; void *mconf; ngx_uint_t m; ngx_conf_t pcf; ngx_stream_module_t *module; ngx_stream_conf_ctx_t *ctx, *stream_ctx; ngx_stream_core_srv_conf_t *cscf, **cscfp; ngx_stream_core_main_conf_t *cmcf; ctx = ngx_pcalloc(cf->pool, sizeof(ngx_stream_conf_ctx_t)); if (ctx == NULL) { return NGX_CONF_ERROR; } stream_ctx = cf->ctx; ctx->main_conf = stream_ctx->main_conf; /* the server{}'s srv_conf */ ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_stream_max_module); if (ctx->srv_conf == NULL) { return NGX_CONF_ERROR; } for (m = 0; cf->cycle->modules[m]; m++) { if (cf->cycle->modules[m]->type != NGX_STREAM_MODULE) { continue; } module = cf->cycle->modules[m]->ctx; if (module->create_srv_conf) { mconf = module->create_srv_conf(cf); if (mconf == NULL) { return NGX_CONF_ERROR; } ctx->srv_conf[cf->cycle->modules[m]->ctx_index] = mconf; } } /* the server configuration context */ cscf = ctx->srv_conf[ngx_stream_core_module.ctx_index]; cscf->ctx = ctx; cmcf = ctx->main_conf[ngx_stream_core_module.ctx_index]; cscfp = ngx_array_push(&cmcf->servers); if (cscfp == NULL) { return NGX_CONF_ERROR; } *cscfp = cscf; /* parse inside server{} */ pcf = *cf; cf->ctx = ctx; cf->cmd_type = NGX_STREAM_SRV_CONF; rv = ngx_conf_parse(cf, NULL); *cf = pcf; if (rv == NGX_CONF_OK && !cscf->listen) { ngx_log_error(NGX_LOG_EMERG, cf->log, 0, "no \"listen\" is defined for server in %s:%ui", cscf->file_name, cscf->line); return NGX_CONF_ERROR; } return rv; } static char * ngx_stream_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_stream_core_srv_conf_t *cscf = conf; ngx_str_t *value, size; ngx_url_t u; ngx_uint_t i, backlog; ngx_stream_listen_t *ls, *als; ngx_stream_core_main_conf_t *cmcf; cscf->listen = 1; value = cf->args->elts; ngx_memzero(&u, sizeof(ngx_url_t)); u.url = value[1]; u.listen = 1; if (ngx_parse_url(cf->pool, &u) != NGX_OK) { if (u.err) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "%s in \"%V\" of the \"listen\" directive", u.err, &u.url); } return NGX_CONF_ERROR; } cmcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_core_module); ls = ngx_array_push(&cmcf->listen); if (ls == NULL) { return NGX_CONF_ERROR; } ngx_memzero(ls, sizeof(ngx_stream_listen_t)); ngx_memcpy(&ls->sockaddr.sockaddr, &u.sockaddr, u.socklen); ls->socklen = u.socklen; ls->backlog = NGX_LISTEN_BACKLOG; ls->rcvbuf = -1; ls->sndbuf = -1; ls->type = SOCK_STREAM; ls->wildcard = u.wildcard; ls->ctx = cf->ctx; #if (NGX_HAVE_INET6) ls->ipv6only = 1; #endif backlog = 0; for (i = 2; i < cf->args->nelts; i++) { #if !(NGX_WIN32) if (ngx_strcmp(value[i].data, "udp") == 0) { ls->type = SOCK_DGRAM; continue; } #endif if (ngx_strcmp(value[i].data, "bind") == 0) { ls->bind = 1; continue; } if (ngx_strncmp(value[i].data, "backlog=", 8) == 0) { ls->backlog = ngx_atoi(value[i].data + 8, value[i].len - 8); ls->bind = 1; if (ls->backlog == NGX_ERROR || ls->backlog == 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid backlog \"%V\"", &value[i]); return NGX_CONF_ERROR; } backlog = 1; continue; } if (ngx_strncmp(value[i].data, "rcvbuf=", 7) == 0) { size.len = value[i].len - 7; size.data = value[i].data + 7; ls->rcvbuf = ngx_parse_size(&size); ls->bind = 1; if (ls->rcvbuf == NGX_ERROR) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid rcvbuf \"%V\"", &value[i]); return NGX_CONF_ERROR; } continue; } if (ngx_strncmp(value[i].data, "sndbuf=", 7) == 0) { size.len = value[i].len - 7; size.data = value[i].data + 7; ls->sndbuf = ngx_parse_size(&size); ls->bind = 1; if (ls->sndbuf == NGX_ERROR) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid sndbuf \"%V\"", &value[i]); return NGX_CONF_ERROR; } continue; } if (ngx_strncmp(value[i].data, "ipv6only=o", 10) == 0) { #if (NGX_HAVE_INET6 && defined IPV6_V6ONLY) size_t len; u_char buf[NGX_SOCKADDR_STRLEN]; if (ls->sockaddr.sockaddr.sa_family == AF_INET6) { if (ngx_strcmp(&value[i].data[10], "n") == 0) { ls->ipv6only = 1; } else if (ngx_strcmp(&value[i].data[10], "ff") == 0) { ls->ipv6only = 0; } else { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid ipv6only flags \"%s\"", &value[i].data[9]); return NGX_CONF_ERROR; } ls->bind = 1; } else { len = ngx_sock_ntop(&ls->sockaddr.sockaddr, ls->socklen, buf, NGX_SOCKADDR_STRLEN, 1); ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "ipv6only is not supported " "on addr \"%*s\", ignored", len, buf); } continue; #else ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "bind ipv6only is not supported " "on this platform"); return NGX_CONF_ERROR; #endif } if (ngx_strcmp(value[i].data, "reuseport") == 0) { #if (NGX_HAVE_REUSEPORT) ls->reuseport = 1; ls->bind = 1; #else ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "reuseport is not supported " "on this platform, ignored"); #endif continue; } if (ngx_strcmp(value[i].data, "ssl") == 0) { #if (NGX_STREAM_SSL) ls->ssl = 1; continue; #else ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "the \"ssl\" parameter requires " "ngx_stream_ssl_module"); return NGX_CONF_ERROR; #endif } if (ngx_strncmp(value[i].data, "so_keepalive=", 13) == 0) { if (ngx_strcmp(&value[i].data[13], "on") == 0) { ls->so_keepalive = 1; } else if (ngx_strcmp(&value[i].data[13], "off") == 0) { ls->so_keepalive = 2; } else { #if (NGX_HAVE_KEEPALIVE_TUNABLE) u_char *p, *end; ngx_str_t s; end = value[i].data + value[i].len; s.data = value[i].data + 13; p = ngx_strlchr(s.data, end, ':'); if (p == NULL) { p = end; } if (p > s.data) { s.len = p - s.data; ls->tcp_keepidle = ngx_parse_time(&s, 1); if (ls->tcp_keepidle == (time_t) NGX_ERROR) { goto invalid_so_keepalive; } } s.data = (p < end) ? (p + 1) : end; p = ngx_strlchr(s.data, end, ':'); if (p == NULL) { p = end; } if (p > s.data) { s.len = p - s.data; ls->tcp_keepintvl = ngx_parse_time(&s, 1); if (ls->tcp_keepintvl == (time_t) NGX_ERROR) { goto invalid_so_keepalive; } } s.data = (p < end) ? (p + 1) : end; if (s.data < end) { s.len = end - s.data; ls->tcp_keepcnt = ngx_atoi(s.data, s.len); if (ls->tcp_keepcnt == NGX_ERROR) { goto invalid_so_keepalive; } } if (ls->tcp_keepidle == 0 && ls->tcp_keepintvl == 0 && ls->tcp_keepcnt == 0) { goto invalid_so_keepalive; } ls->so_keepalive = 1; #else ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "the \"so_keepalive\" parameter accepts " "only \"on\" or \"off\" on this platform"); return NGX_CONF_ERROR; #endif } ls->bind = 1; continue; #if (NGX_HAVE_KEEPALIVE_TUNABLE) invalid_so_keepalive: ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid so_keepalive value: \"%s\"", &value[i].data[13]); return NGX_CONF_ERROR; #endif } if (ngx_strcmp(value[i].data, "proxy_protocol") == 0) { ls->proxy_protocol = 1; continue; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "the invalid \"%V\" parameter", &value[i]); return NGX_CONF_ERROR; } if (ls->type == SOCK_DGRAM) { if (backlog) { return "\"backlog\" parameter is incompatible with \"udp\""; } #if (NGX_STREAM_SSL) if (ls->ssl) { return "\"ssl\" parameter is incompatible with \"udp\""; } #endif if (ls->so_keepalive) { return "\"so_keepalive\" parameter is incompatible with \"udp\""; } if (ls->proxy_protocol) { return "\"proxy_protocol\" parameter is incompatible with \"udp\""; } } als = cmcf->listen.elts; for (i = 0; i < cmcf->listen.nelts - 1; i++) { if (ls->type != als[i].type) { continue; } if (ngx_cmp_sockaddr(&als[i].sockaddr.sockaddr, als[i].socklen, &ls->sockaddr.sockaddr, ls->socklen, 1) != NGX_OK) { continue; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "duplicate \"%V\" address and port pair", &u.url); return NGX_CONF_ERROR; } return NGX_CONF_OK; } static char * ngx_stream_core_resolver(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_stream_core_srv_conf_t *cscf = conf; ngx_str_t *value; if (cscf->resolver) { return "is duplicate"; } value = cf->args->elts; cscf->resolver = ngx_resolver_create(cf, &value[1], cf->args->nelts - 1); if (cscf->resolver == NULL) { return NGX_CONF_ERROR; } return NGX_CONF_OK; }