Mercurial > hg > nginx-quic
view src/stream/ngx_stream_core_module.c @ 7507:ea05113adbdb
Range filter: fixed loss of incoming chain links.
Filters are not allowed to change incoming chain links, and should allocate
their own links if any modifications are needed. Nevertheless
ngx_http_range_singlepart_body() modified incoming chain links in some
cases, notably at the end of the requested range.
No problems caused by this are currently known, mostly because of
limited number of possible modifications and the position of the range
body filter in the filter chain. Though this behaviour is clearly incorrect
and tests demonstrate that it can at least cause some proxy buffers being
lost when using proxy_force_ranges, leading to less effective handling
of responses.
Fix is to always allocate new chain links in ngx_http_range_singlepart_body().
Links are explicitly freed to ensure constant memory usage with long-lived
requests.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 13 May 2019 22:44:02 +0300 |
parents | 4f9b72a229c1 |
children | 893b3313f53c 2ab7b55ae4a0 |
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/* * 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) { break; } n = c->recv(c, c->buffer->last, size); if (n == NGX_ERROR || n == 0) { rc = NGX_STREAM_OK; break; } if (n == NGX_AGAIN) { break; } c->buffer->last += n; rc = ph->handler(s); } if (rc == NGX_AGAIN) { if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR); return NGX_OK; } if (!c->read->timer_set) { ngx_add_timer(c->read, cscf->preread_timeout); } c->read->handler = ngx_stream_session_handler; return NGX_OK; } 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, n, 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_n(&cmcf->listen, u.naddrs); if (ls == NULL) { return NGX_CONF_ERROR; } ngx_memzero(ls, sizeof(ngx_stream_listen_t)); ls->backlog = NGX_LISTEN_BACKLOG; ls->rcvbuf = -1; ls->sndbuf = -1; ls->type = SOCK_STREAM; 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) 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; 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) ngx_stream_ssl_conf_t *sslcf; sslcf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_ssl_module); sslcf->listen = 1; sslcf->file = cf->conf_file->file.name.data; sslcf->line = cf->conf_file->line; 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 (n = 0; n < u.naddrs; n++) { ls[n] = ls[0]; ls[n].sockaddr = u.addrs[n].sockaddr; ls[n].socklen = u.addrs[n].socklen; ls[n].addr_text = u.addrs[n].name; ls[n].wildcard = ngx_inet_wildcard(ls[n].sockaddr); for (i = 0; i < cmcf->listen.nelts - u.naddrs + n; i++) { if (ls[n].type != als[i].type) { continue; } if (ngx_cmp_sockaddr(als[i].sockaddr, als[i].socklen, ls[n].sockaddr, ls[n].socklen, 1) != NGX_OK) { continue; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "duplicate \"%V\" address and port pair", &ls[n].addr_text); 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; }