<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html xmlns:fn="http://www.w3.org/2005/02/xpath-functions"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link rel="stylesheet" href="../../../../doc/otp_doc.css" type="text/css"> <title>Erlang -- inet_res</title> </head> <body bgcolor="white" text="#000000" link="#0000ff" vlink="#ff00ff" alink="#ff0000"><div id="container"> <script id="js" type="text/javascript" language="JavaScript" src="../../../../doc/js/flipmenu/flipmenu.js"></script><script id="js2" type="text/javascript" src="../../../../doc/js/erlresolvelinks.js"></script><script language="JavaScript" type="text/javascript"> <!-- function getWinHeight() { var myHeight = 0; if( typeof( window.innerHeight ) == 'number' ) { //Non-IE myHeight = window.innerHeight; } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) { //IE 6+ in 'standards compliant mode' myHeight = 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href="../../../../doc/index.html">Top</a></small><p><strong>Kernel</strong><br><strong>Reference Manual</strong><br><small>Version 2.13.5</small></p> <br><a href="javascript:openAllFlips()">Expand All</a><br><a href="javascript:closeAllFlips()">Contract All</a><p><small><strong>Table of Contents</strong></small></p> <ul class="flipMenu"> <li title="kernel (App)"><a href="kernel_app.html">kernel (App) </a></li> <li id="no" title="application " expanded="false">application<ul> <li><a href="application.html"> Top of manual page </a></li> <li title="get_all_env-0"><a href="application.html#get_all_env-0">get_all_env/0</a></li> <li title="get_all_env-1"><a href="application.html#get_all_env-1">get_all_env/1</a></li> <li title="get_all_key-0"><a href="application.html#get_all_key-0">get_all_key/0</a></li> <li title="get_all_key-1"><a href="application.html#get_all_key-1">get_all_key/1</a></li> <li title="get_application-0"><a href="application.html#get_application-0">get_application/0</a></li> <li title="get_application-1"><a href="application.html#get_application-1">get_application/1</a></li> <li title="get_env-1"><a href="application.html#get_env-1">get_env/1</a></li> <li title="get_env-2"><a href="application.html#get_env-2">get_env/2</a></li> <li title="get_key-1"><a href="application.html#get_key-1">get_key/1</a></li> <li title="get_key-2"><a href="application.html#get_key-2">get_key/2</a></li> <li title="load-1"><a href="application.html#load-1">load/1</a></li> <li title="load-2"><a href="application.html#load-2">load/2</a></li> <li title="loaded_applications-0"><a href="application.html#loaded_applications-0">loaded_applications/0</a></li> <li title="permit-2"><a href="application.html#permit-2">permit/2</a></li> <li title="set_env-3"><a href="application.html#set_env-3">set_env/3</a></li> <li title="set_env-4"><a href="application.html#set_env-4">set_env/4</a></li> <li title="start-1"><a href="application.html#start-1">start/1</a></li> <li title="start-2"><a href="application.html#start-2">start/2</a></li> <li title="start_type-0"><a href="application.html#start_type-0">start_type/0</a></li> <li title="stop-1"><a href="application.html#stop-1">stop/1</a></li> <li title="takeover-2"><a href="application.html#takeover-2">takeover/2</a></li> <li title="unload-1"><a href="application.html#unload-1">unload/1</a></li> <li title="unset_env-2"><a href="application.html#unset_env-2">unset_env/2</a></li> <li title="unset_env-3"><a href="application.html#unset_env-3">unset_env/3</a></li> <li title="which_applications-0"><a href="application.html#which_applications-0">which_applications/0</a></li> <li title="which_applications-1"><a href="application.html#which_applications-1">which_applications/1</a></li> <li title="Module:start-2"><a href="application.html#Module:start-2">Module:start/2</a></li> <li title="Module:start_phase-3"><a href="application.html#Module:start_phase-3">Module:start_phase/3</a></li> <li title="Module:prep_stop-1"><a href="application.html#Module:prep_stop-1">Module:prep_stop/1</a></li> <li title="Module:stop-1"><a href="application.html#Module:stop-1">Module:stop/1</a></li> <li title="Module:config_change-3"><a href="application.html#Module:config_change-3">Module:config_change/3</a></li> </ul> </li> <li id="no" title="auth " expanded="false">auth<ul> <li><a href="auth.html"> Top of manual page </a></li> <li title="is_auth-1"><a href="auth.html#is_auth-1">is_auth/1</a></li> <li title="cookie-0"><a href="auth.html#cookie-0">cookie/0</a></li> <li title="cookie-1"><a href="auth.html#cookie-1">cookie/1</a></li> <li title="node_cookie-1"><a href="auth.html#node_cookie-1">node_cookie/1</a></li> <li title="node_cookie-2"><a href="auth.html#node_cookie-2">node_cookie/2</a></li> </ul> </li> <li id="no" title="code " expanded="false">code<ul> <li><a href="code.html"> Top of manual page </a></li> <li title="set_path-1"><a href="code.html#set_path-1">set_path/1</a></li> <li title="get_path-0"><a href="code.html#get_path-0">get_path/0</a></li> <li title="add_path-1"><a href="code.html#add_path-1">add_path/1</a></li> <li title="add_pathz-1"><a href="code.html#add_pathz-1">add_pathz/1</a></li> <li title="add_patha-1"><a href="code.html#add_patha-1">add_patha/1</a></li> <li title="add_paths-1"><a href="code.html#add_paths-1">add_paths/1</a></li> <li title="add_pathsz-1"><a href="code.html#add_pathsz-1">add_pathsz/1</a></li> <li title="add_pathsa-1"><a href="code.html#add_pathsa-1">add_pathsa/1</a></li> <li title="del_path-1"><a href="code.html#del_path-1">del_path/1</a></li> <li title="replace_path-2"><a href="code.html#replace_path-2">replace_path/2</a></li> <li title="load_file-1"><a href="code.html#load_file-1">load_file/1</a></li> <li title="load_abs-1"><a href="code.html#load_abs-1">load_abs/1</a></li> <li title="ensure_loaded-1"><a href="code.html#ensure_loaded-1">ensure_loaded/1</a></li> <li title="load_binary-3"><a href="code.html#load_binary-3">load_binary/3</a></li> <li title="delete-1"><a href="code.html#delete-1">delete/1</a></li> <li title="purge-1"><a href="code.html#purge-1">purge/1</a></li> <li title="soft_purge-1"><a href="code.html#soft_purge-1">soft_purge/1</a></li> <li title="is_loaded-1"><a href="code.html#is_loaded-1">is_loaded/1</a></li> <li title="all_loaded-0"><a href="code.html#all_loaded-0">all_loaded/0</a></li> <li title="which-1"><a href="code.html#which-1">which/1</a></li> <li title="get_object_code-1"><a href="code.html#get_object_code-1">get_object_code/1</a></li> <li title="root_dir-0"><a href="code.html#root_dir-0">root_dir/0</a></li> <li title="lib_dir-0"><a href="code.html#lib_dir-0">lib_dir/0</a></li> <li title="lib_dir-1"><a href="code.html#lib_dir-1">lib_dir/1</a></li> <li title="lib_dir-2"><a href="code.html#lib_dir-2">lib_dir/2</a></li> <li title="compiler_dir-0"><a href="code.html#compiler_dir-0">compiler_dir/0</a></li> <li title="priv_dir-1"><a href="code.html#priv_dir-1">priv_dir/1</a></li> <li title="objfile_extension-0"><a href="code.html#objfile_extension-0">objfile_extension/0</a></li> <li title="stick_dir-1"><a href="code.html#stick_dir-1">stick_dir/1</a></li> <li title="unstick_dir-1"><a href="code.html#unstick_dir-1">unstick_dir/1</a></li> <li title="is_sticky-1"><a href="code.html#is_sticky-1">is_sticky/1</a></li> <li title="rehash-0"><a href="code.html#rehash-0">rehash/0</a></li> <li title="where_is_file-1"><a href="code.html#where_is_file-1">where_is_file/1</a></li> <li title="clash-0"><a href="code.html#clash-0">clash/0</a></li> <li title="is_module_native-1"><a href="code.html#is_module_native-1">is_module_native/1</a></li> </ul> </li> <li id="no" title="disk_log " expanded="false">disk_log<ul> <li><a href="disk_log.html"> Top of manual page </a></li> <li title="accessible_logs-0"><a href="disk_log.html#accessible_logs-0">accessible_logs/0</a></li> <li title="alog-2"><a href="disk_log.html#alog-2">alog/2</a></li> <li title="balog-2"><a href="disk_log.html#balog-2">balog/2</a></li> <li title="alog_terms-2"><a href="disk_log.html#alog_terms-2">alog_terms/2</a></li> <li title="balog_terms-2"><a href="disk_log.html#balog_terms-2">balog_terms/2</a></li> <li title="block-1"><a href="disk_log.html#block-1">block/1</a></li> <li title="block-2"><a href="disk_log.html#block-2">block/2</a></li> <li title="change_header-2"><a href="disk_log.html#change_header-2">change_header/2</a></li> <li title="change_notify-3"><a href="disk_log.html#change_notify-3">change_notify/3</a></li> <li title="change_size-2"><a href="disk_log.html#change_size-2">change_size/2</a></li> <li title="chunk-2"><a href="disk_log.html#chunk-2">chunk/2</a></li> <li title="chunk-3"><a href="disk_log.html#chunk-3">chunk/3</a></li> <li title="bchunk-2"><a href="disk_log.html#bchunk-2">bchunk/2</a></li> <li title="bchunk-3"><a href="disk_log.html#bchunk-3">bchunk/3</a></li> <li title="chunk_info-1"><a href="disk_log.html#chunk_info-1">chunk_info/1</a></li> <li title="chunk_step-3"><a href="disk_log.html#chunk_step-3">chunk_step/3</a></li> <li title="close-1"><a href="disk_log.html#close-1">close/1</a></li> <li title="format_error-1"><a href="disk_log.html#format_error-1">format_error/1</a></li> <li title="inc_wrap_file-1"><a href="disk_log.html#inc_wrap_file-1">inc_wrap_file/1</a></li> <li title="info-1"><a href="disk_log.html#info-1">info/1</a></li> <li title="lclose-1"><a href="disk_log.html#lclose-1">lclose/1</a></li> <li title="lclose-2"><a href="disk_log.html#lclose-2">lclose/2</a></li> <li title="log-2"><a href="disk_log.html#log-2">log/2</a></li> <li title="blog-2"><a href="disk_log.html#blog-2">blog/2</a></li> <li title="log_terms-2"><a href="disk_log.html#log_terms-2">log_terms/2</a></li> <li title="blog_terms-2"><a href="disk_log.html#blog_terms-2">blog_terms/2</a></li> <li title="open-1"><a href="disk_log.html#open-1">open/1</a></li> <li title="pid2name-1"><a href="disk_log.html#pid2name-1">pid2name/1</a></li> <li title="reopen-2"><a href="disk_log.html#reopen-2">reopen/2</a></li> <li title="reopen-3"><a href="disk_log.html#reopen-3">reopen/3</a></li> <li title="breopen-3"><a href="disk_log.html#breopen-3">breopen/3</a></li> <li title="sync-1"><a href="disk_log.html#sync-1">sync/1</a></li> <li title="truncate-1"><a href="disk_log.html#truncate-1">truncate/1</a></li> <li title="truncate-2"><a href="disk_log.html#truncate-2">truncate/2</a></li> <li title="btruncate-2"><a href="disk_log.html#btruncate-2">btruncate/2</a></li> <li title="unblock-1"><a href="disk_log.html#unblock-1">unblock/1</a></li> </ul> </li> <li id="no" title="erl_boot_server " expanded="false">erl_boot_server<ul> <li><a href="erl_boot_server.html"> Top of manual page </a></li> <li title="start-1"><a href="erl_boot_server.html#start-1">start/1</a></li> <li title="start_link-1"><a href="erl_boot_server.html#start_link-1">start_link/1</a></li> <li title="add_slave-1"><a href="erl_boot_server.html#add_slave-1">add_slave/1</a></li> <li title="delete_slave-1"><a href="erl_boot_server.html#delete_slave-1">delete_slave/1</a></li> <li title="which_slaves-0"><a href="erl_boot_server.html#which_slaves-0">which_slaves/0</a></li> </ul> </li> <li id="no" title="erl_ddll " expanded="false">erl_ddll<ul> <li><a href="erl_ddll.html"> Top of manual page </a></li> <li title="demonitor-1"><a href="erl_ddll.html#demonitor-1">demonitor/1</a></li> <li title="info-0"><a href="erl_ddll.html#info-0">info/0</a></li> <li title="info-1"><a href="erl_ddll.html#info-1">info/1</a></li> <li title="info-2"><a href="erl_ddll.html#info-2">info/2</a></li> <li title="load-2"><a href="erl_ddll.html#load-2">load/2</a></li> <li title="load_driver-2"><a href="erl_ddll.html#load_driver-2">load_driver/2</a></li> <li title="monitor-2"><a href="erl_ddll.html#monitor-2">monitor/2</a></li> <li title="reload-2"><a href="erl_ddll.html#reload-2">reload/2</a></li> <li title="reload_driver-2"><a href="erl_ddll.html#reload_driver-2">reload_driver/2</a></li> <li title="try_load-3"><a href="erl_ddll.html#try_load-3">try_load/3</a></li> <li title="try_unload-2"><a href="erl_ddll.html#try_unload-2">try_unload/2</a></li> <li title="unload-1"><a href="erl_ddll.html#unload-1">unload/1</a></li> <li title="unload_driver-1"><a href="erl_ddll.html#unload_driver-1">unload_driver/1</a></li> <li title="loaded_drivers-0"><a href="erl_ddll.html#loaded_drivers-0">loaded_drivers/0</a></li> <li title="format_error-1"><a href="erl_ddll.html#format_error-1">format_error/1</a></li> </ul> </li> <li title="erl_prim_loader"><a href="erl_prim_loader.html">erl_prim_loader</a></li> <li title="erlang"><a href="erlang.html">erlang</a></li> <li id="no" title="error_handler " expanded="false">error_handler<ul> <li><a href="error_handler.html"> Top of manual page </a></li> <li title="undefined_function-3"><a href="error_handler.html#undefined_function-3">undefined_function/3</a></li> <li title="undefined_lambda-3"><a href="error_handler.html#undefined_lambda-3">undefined_lambda/3</a></li> </ul> </li> <li id="no" title="error_logger " expanded="false">error_logger<ul> <li><a href="error_logger.html"> Top of manual page </a></li> <li title="error_msg-1"><a href="error_logger.html#error_msg-1">error_msg/1</a></li> <li title="error_msg-2"><a href="error_logger.html#error_msg-2">error_msg/2</a></li> <li title="format-2"><a href="error_logger.html#format-2">format/2</a></li> <li title="error_report-1"><a href="error_logger.html#error_report-1">error_report/1</a></li> <li title="error_report-2"><a href="error_logger.html#error_report-2">error_report/2</a></li> <li title="warning_map-0"><a href="error_logger.html#warning_map-0">warning_map/0</a></li> <li title="warning_msg-1"><a href="error_logger.html#warning_msg-1">warning_msg/1</a></li> <li title="warning_msg-2"><a href="error_logger.html#warning_msg-2">warning_msg/2</a></li> <li title="warning_report-1"><a href="error_logger.html#warning_report-1">warning_report/1</a></li> <li title="warning_report-2"><a href="error_logger.html#warning_report-2">warning_report/2</a></li> <li title="info_msg-1"><a href="error_logger.html#info_msg-1">info_msg/1</a></li> <li title="info_msg-2"><a href="error_logger.html#info_msg-2">info_msg/2</a></li> <li title="info_report-1"><a href="error_logger.html#info_report-1">info_report/1</a></li> <li title="info_report-2"><a href="error_logger.html#info_report-2">info_report/2</a></li> <li title="add_report_handler-1"><a href="error_logger.html#add_report_handler-1">add_report_handler/1</a></li> <li title="add_report_handler-2"><a href="error_logger.html#add_report_handler-2">add_report_handler/2</a></li> <li title="delete_report_handler-1"><a href="error_logger.html#delete_report_handler-1">delete_report_handler/1</a></li> <li title="tty-1"><a href="error_logger.html#tty-1">tty/1</a></li> <li title="logfile-1"><a href="error_logger.html#logfile-1">logfile/1</a></li> </ul> </li> <li id="no" title="file " expanded="false">file<ul> <li><a href="file.html"> Top of manual page </a></li> <li title="change_group-2"><a href="file.html#change_group-2">change_group/2</a></li> <li title="change_owner-2"><a href="file.html#change_owner-2">change_owner/2</a></li> <li title="change_owner-3"><a href="file.html#change_owner-3">change_owner/3</a></li> <li title="change_time-2"><a href="file.html#change_time-2">change_time/2</a></li> <li title="change_time-3"><a href="file.html#change_time-3">change_time/3</a></li> <li title="close-1"><a href="file.html#close-1">close/1</a></li> <li title="consult-1"><a href="file.html#consult-1">consult/1</a></li> <li title="copy-2"><a href="file.html#copy-2">copy/2</a></li> <li title="copy-3"><a href="file.html#copy-3">copy/3</a></li> <li title="del_dir-1"><a href="file.html#del_dir-1">del_dir/1</a></li> <li title="delete-1"><a href="file.html#delete-1">delete/1</a></li> <li title="eval-1"><a href="file.html#eval-1">eval/1</a></li> <li title="eval-2"><a href="file.html#eval-2">eval/2</a></li> <li title="file_info-1"><a href="file.html#file_info-1">file_info/1</a></li> <li title="format_error-1"><a href="file.html#format_error-1">format_error/1</a></li> <li title="get_cwd-0"><a href="file.html#get_cwd-0">get_cwd/0</a></li> <li title="get_cwd-1"><a href="file.html#get_cwd-1">get_cwd/1</a></li> <li title="list_dir-1"><a href="file.html#list_dir-1">list_dir/1</a></li> <li title="make_dir-1"><a href="file.html#make_dir-1">make_dir/1</a></li> <li title="make_link-2"><a href="file.html#make_link-2">make_link/2</a></li> <li title="make_symlink-2"><a href="file.html#make_symlink-2">make_symlink/2</a></li> <li title="open-2"><a href="file.html#open-2">open/2</a></li> <li title="path_consult-2"><a href="file.html#path_consult-2">path_consult/2</a></li> <li title="path_eval-2"><a href="file.html#path_eval-2">path_eval/2</a></li> <li title="path_open-3"><a href="file.html#path_open-3">path_open/3</a></li> <li title="path_script-2"><a href="file.html#path_script-2">path_script/2</a></li> <li title="path_script-3"><a href="file.html#path_script-3">path_script/3</a></li> <li title="pid2name-1"><a href="file.html#pid2name-1">pid2name/1</a></li> <li title="position-2"><a href="file.html#position-2">position/2</a></li> <li title="pread-2"><a href="file.html#pread-2">pread/2</a></li> <li title="pread-3"><a href="file.html#pread-3">pread/3</a></li> <li title="pwrite-2"><a href="file.html#pwrite-2">pwrite/2</a></li> <li title="pwrite-3"><a href="file.html#pwrite-3">pwrite/3</a></li> <li title="read-2"><a href="file.html#read-2">read/2</a></li> <li title="read_file-1"><a href="file.html#read_file-1">read_file/1</a></li> <li title="read_file_info-1"><a href="file.html#read_file_info-1">read_file_info/1</a></li> <li title="read_line-1"><a href="file.html#read_line-1">read_line/1</a></li> <li title="read_link-1"><a href="file.html#read_link-1">read_link/1</a></li> <li title="read_link_info-1"><a href="file.html#read_link_info-1">read_link_info/1</a></li> <li title="rename-2"><a href="file.html#rename-2">rename/2</a></li> <li title="script-1"><a href="file.html#script-1">script/1</a></li> <li title="script-2"><a href="file.html#script-2">script/2</a></li> <li title="set_cwd-1"><a href="file.html#set_cwd-1">set_cwd/1</a></li> <li title="sync-1"><a href="file.html#sync-1">sync/1</a></li> <li title="truncate-1"><a href="file.html#truncate-1">truncate/1</a></li> <li title="write-2"><a href="file.html#write-2">write/2</a></li> <li title="write_file-2"><a href="file.html#write_file-2">write_file/2</a></li> <li title="write_file-3"><a href="file.html#write_file-3">write_file/3</a></li> <li title="write_file_info-2"><a href="file.html#write_file_info-2">write_file_info/2</a></li> </ul> </li> <li id="no" title="gen_tcp " expanded="false">gen_tcp<ul> <li><a href="gen_tcp.html"> Top of manual page </a></li> <li title="connect-3"><a href="gen_tcp.html#connect-3">connect/3</a></li> <li title="connect-4"><a href="gen_tcp.html#connect-4">connect/4</a></li> <li title="listen-2"><a href="gen_tcp.html#listen-2">listen/2</a></li> <li title="accept-1"><a href="gen_tcp.html#accept-1">accept/1</a></li> <li title="accept-2"><a href="gen_tcp.html#accept-2">accept/2</a></li> <li title="send-2"><a href="gen_tcp.html#send-2">send/2</a></li> <li title="recv-2"><a href="gen_tcp.html#recv-2">recv/2</a></li> <li title="recv-3"><a href="gen_tcp.html#recv-3">recv/3</a></li> <li title="controlling_process-2"><a href="gen_tcp.html#controlling_process-2">controlling_process/2</a></li> <li title="close-1"><a href="gen_tcp.html#close-1">close/1</a></li> <li title="shutdown-2"><a href="gen_tcp.html#shutdown-2">shutdown/2</a></li> </ul> </li> <li id="no" title="gen_udp " expanded="false">gen_udp<ul> <li><a href="gen_udp.html"> Top of manual page </a></li> <li title="open-1"><a href="gen_udp.html#open-1">open/1</a></li> <li title="open-2"><a href="gen_udp.html#open-2">open/2</a></li> <li title="send-4"><a href="gen_udp.html#send-4">send/4</a></li> <li title="recv-2"><a href="gen_udp.html#recv-2">recv/2</a></li> <li title="recv-3"><a href="gen_udp.html#recv-3">recv/3</a></li> <li title="controlling_process-2"><a href="gen_udp.html#controlling_process-2">controlling_process/2</a></li> <li title="close-1"><a href="gen_udp.html#close-1">close/1</a></li> </ul> </li> <li id="no" title="gen_sctp " expanded="false">gen_sctp<ul> <li><a href="gen_sctp.html"> Top of manual page </a></li> <li title="abort-2"><a href="gen_sctp.html#abort-2">abort/2</a></li> <li title="close-1"><a href="gen_sctp.html#close-1">close/1</a></li> <li title="connect-4"><a href="gen_sctp.html#connect-4">connect/4</a></li> <li title="connect-5"><a href="gen_sctp.html#connect-5">connect/5</a></li> <li title="connect_init-4"><a href="gen_sctp.html#connect_init-4">connect_init/4</a></li> <li title="connect_init-5"><a href="gen_sctp.html#connect_init-5">connect_init/5</a></li> <li title="controlling_process-2"><a href="gen_sctp.html#controlling_process-2">controlling_process/2</a></li> <li title="eof-2"><a href="gen_sctp.html#eof-2">eof/2</a></li> <li title="listen-2"><a href="gen_sctp.html#listen-2">listen/2</a></li> <li title="open-0"><a href="gen_sctp.html#open-0">open/0</a></li> <li title="open-1"><a href="gen_sctp.html#open-1">open/1</a></li> <li title="open-1"><a href="gen_sctp.html#open-1">open/1</a></li> <li title="open-2"><a href="gen_sctp.html#open-2">open/2</a></li> <li title="recv-1"><a href="gen_sctp.html#recv-1">recv/1</a></li> <li title="recv-2"><a href="gen_sctp.html#recv-2">recv/2</a></li> <li title="send-3"><a href="gen_sctp.html#send-3">send/3</a></li> <li title="send-4"><a href="gen_sctp.html#send-4">send/4</a></li> <li title="error_string-1"><a href="gen_sctp.html#error_string-1">error_string/1</a></li> </ul> </li> <li id="no" title="global " expanded="false">global<ul> <li><a href="global.html"> Top of manual page </a></li> <li title="del_lock-1"><a href="global.html#del_lock-1">del_lock/1</a></li> <li title="del_lock-2"><a href="global.html#del_lock-2">del_lock/2</a></li> <li title="notify_all_name-3"><a href="global.html#notify_all_name-3">notify_all_name/3</a></li> <li title="random_exit_name-3"><a href="global.html#random_exit_name-3">random_exit_name/3</a></li> <li title="random_notify_name-3"><a href="global.html#random_notify_name-3">random_notify_name/3</a></li> <li title="register_name-2"><a href="global.html#register_name-2">register_name/2</a></li> <li title="register_name-3"><a href="global.html#register_name-3">register_name/3</a></li> <li title="registered_names-0"><a href="global.html#registered_names-0">registered_names/0</a></li> <li title="re_register_name-2"><a href="global.html#re_register_name-2">re_register_name/2</a></li> <li title="re_register_name-3"><a href="global.html#re_register_name-3">re_register_name/3</a></li> <li title="send-2"><a href="global.html#send-2">send/2</a></li> <li title="set_lock-1"><a href="global.html#set_lock-1">set_lock/1</a></li> <li title="set_lock-2"><a href="global.html#set_lock-2">set_lock/2</a></li> <li title="set_lock-3"><a href="global.html#set_lock-3">set_lock/3</a></li> <li title="sync-0"><a href="global.html#sync-0">sync/0</a></li> <li title="trans-2"><a href="global.html#trans-2">trans/2</a></li> <li title="trans-3"><a href="global.html#trans-3">trans/3</a></li> <li title="trans-4"><a href="global.html#trans-4">trans/4</a></li> <li title="unregister_name-1"><a href="global.html#unregister_name-1">unregister_name/1</a></li> <li title="whereis_name-1"><a href="global.html#whereis_name-1">whereis_name/1</a></li> </ul> </li> <li id="no" title="global_group " expanded="false">global_group<ul> <li><a href="global_group.html"> Top of manual page </a></li> <li title="global_groups-0"><a href="global_group.html#global_groups-0">global_groups/0</a></li> <li title="info-0"><a href="global_group.html#info-0">info/0</a></li> <li title="monitor_nodes-1"><a href="global_group.html#monitor_nodes-1">monitor_nodes/1</a></li> <li title="own_nodes-0"><a href="global_group.html#own_nodes-0">own_nodes/0</a></li> <li title="registered_names-1"><a href="global_group.html#registered_names-1">registered_names/1</a></li> <li title="send-2"><a href="global_group.html#send-2">send/2</a></li> <li title="send-3"><a href="global_group.html#send-3">send/3</a></li> <li title="sync-0"><a href="global_group.html#sync-0">sync/0</a></li> <li title="whereis_name-1"><a href="global_group.html#whereis_name-1">whereis_name/1</a></li> <li title="whereis_name-2"><a href="global_group.html#whereis_name-2">whereis_name/2</a></li> </ul> </li> <li id="no" title="heart " expanded="false">heart<ul> <li><a href="heart.html"> Top of manual page </a></li> <li title="set_cmd-1"><a href="heart.html#set_cmd-1">set_cmd/1</a></li> <li title="clear_cmd-0"><a href="heart.html#clear_cmd-0">clear_cmd/0</a></li> <li title="get_cmd-0"><a href="heart.html#get_cmd-0">get_cmd/0</a></li> </ul> </li> <li id="no" title="inet " expanded="false">inet<ul> <li><a href="inet.html"> Top of manual page </a></li> <li title="close-1"><a href="inet.html#close-1">close/1</a></li> <li title="get_rc-0"><a href="inet.html#get_rc-0">get_rc/0</a></li> <li title="format_error-1"><a href="inet.html#format_error-1">format_error/1</a></li> <li title="getaddr-2"><a href="inet.html#getaddr-2">getaddr/2</a></li> <li title="getaddrs-2"><a href="inet.html#getaddrs-2">getaddrs/2</a></li> <li title="gethostbyaddr-1"><a href="inet.html#gethostbyaddr-1">gethostbyaddr/1</a></li> <li title="gethostbyname-1"><a href="inet.html#gethostbyname-1">gethostbyname/1</a></li> <li title="gethostbyname-2"><a href="inet.html#gethostbyname-2">gethostbyname/2</a></li> <li title="gethostname-0"><a href="inet.html#gethostname-0">gethostname/0</a></li> <li title="getopts-2"><a href="inet.html#getopts-2">getopts/2</a></li> <li title="getstat-1"><a href="inet.html#getstat-1">getstat/1</a></li> <li title="getstat-2"><a href="inet.html#getstat-2">getstat/2</a></li> <li title="peername-1"><a href="inet.html#peername-1">peername/1</a></li> <li title="port-1"><a href="inet.html#port-1">port/1</a></li> <li title="sockname-1"><a href="inet.html#sockname-1">sockname/1</a></li> <li title="setopts-2"><a href="inet.html#setopts-2">setopts/2</a></li> </ul> </li> <li id="loadscrollpos" title="inet_res " expanded="true">inet_res<ul> <li><a href="inet_res.html"> Top of manual page </a></li> <li title="getbyname-2"><a href="inet_res.html#getbyname-2">getbyname/2</a></li> <li title="getbyname-3"><a href="inet_res.html#getbyname-3">getbyname/3</a></li> <li title="gethostbyaddr-1"><a href="inet_res.html#gethostbyaddr-1">gethostbyaddr/1</a></li> <li title="gethostbyaddr-2"><a href="inet_res.html#gethostbyaddr-2">gethostbyaddr/2</a></li> <li title="gethostbyname-1"><a href="inet_res.html#gethostbyname-1">gethostbyname/1</a></li> <li title="gethostbyname-2"><a href="inet_res.html#gethostbyname-2">gethostbyname/2</a></li> <li title="gethostbyname-3"><a href="inet_res.html#gethostbyname-3">gethostbyname/3</a></li> <li title="lookup-3"><a href="inet_res.html#lookup-3">lookup/3</a></li> <li title="lookup-4"><a href="inet_res.html#lookup-4">lookup/4</a></li> <li title="lookup-5"><a href="inet_res.html#lookup-5">lookup/5</a></li> <li title="resolve-3"><a href="inet_res.html#resolve-3">resolve/3</a></li> <li title="resolve-4"><a href="inet_res.html#resolve-4">resolve/4</a></li> <li title="resolve-5"><a href="inet_res.html#resolve-5">resolve/5</a></li> <li title="nslookup-3"><a href="inet_res.html#nslookup-3">nslookup/3</a></li> <li title="nslookup-4"><a href="inet_res.html#nslookup-4">nslookup/4</a></li> <li title="nslookup-4"><a href="inet_res.html#nslookup-4">nslookup/4</a></li> <li title="nnslookup-4"><a href="inet_res.html#nnslookup-4">nnslookup/4</a></li> <li title="nnslookup-5"><a href="inet_res.html#nnslookup-5">nnslookup/5</a></li> </ul> </li> <li title="init"><a href="init.html">init</a></li> <li id="no" title="net_adm " expanded="false">net_adm<ul> <li><a href="net_adm.html"> Top of manual page </a></li> <li title="dns_hostname-1"><a href="net_adm.html#dns_hostname-1">dns_hostname/1</a></li> <li title="host_file-0"><a href="net_adm.html#host_file-0">host_file/0</a></li> <li title="localhost-0"><a href="net_adm.html#localhost-0">localhost/0</a></li> <li title="names-0"><a href="net_adm.html#names-0">names/0</a></li> <li title="names-1"><a href="net_adm.html#names-1">names/1</a></li> <li title="ping-1"><a href="net_adm.html#ping-1">ping/1</a></li> <li title="world-0"><a href="net_adm.html#world-0">world/0</a></li> <li title="world-1"><a href="net_adm.html#world-1">world/1</a></li> <li title="world_list-1"><a href="net_adm.html#world_list-1">world_list/1</a></li> <li title="world_list-2"><a href="net_adm.html#world_list-2">world_list/2</a></li> </ul> </li> <li id="no" title="net_kernel " expanded="false">net_kernel<ul> <li><a href="net_kernel.html"> Top of manual page </a></li> <li title="allow-1"><a href="net_kernel.html#allow-1">allow/1</a></li> <li title="connect_node-1"><a href="net_kernel.html#connect_node-1">connect_node/1</a></li> <li title="monitor_nodes-1"><a href="net_kernel.html#monitor_nodes-1">monitor_nodes/1</a></li> <li title="monitor_nodes-2"><a href="net_kernel.html#monitor_nodes-2">monitor_nodes/2</a></li> <li title="get_net_ticktime-0"><a href="net_kernel.html#get_net_ticktime-0">get_net_ticktime/0</a></li> <li title="set_net_ticktime-1"><a href="net_kernel.html#set_net_ticktime-1">set_net_ticktime/1</a></li> <li title="set_net_ticktime-2"><a href="net_kernel.html#set_net_ticktime-2">set_net_ticktime/2</a></li> <li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li> <li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li> <li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li> <li title="stop-0"><a href="net_kernel.html#stop-0">stop/0</a></li> </ul> </li> <li id="no" title="os " expanded="false">os<ul> <li><a href="os.html"> Top of manual page </a></li> <li title="cmd-1"><a href="os.html#cmd-1">cmd/1</a></li> <li title="find_executable-1"><a href="os.html#find_executable-1">find_executable/1</a></li> <li title="find_executable-2"><a href="os.html#find_executable-2">find_executable/2</a></li> <li title="getenv-0"><a href="os.html#getenv-0">getenv/0</a></li> <li title="getenv-1"><a href="os.html#getenv-1">getenv/1</a></li> <li title="getpid-0"><a href="os.html#getpid-0">getpid/0</a></li> <li title="putenv-2"><a href="os.html#putenv-2">putenv/2</a></li> <li title="timestamp-0"><a href="os.html#timestamp-0">timestamp/0</a></li> <li title="type-0"><a href="os.html#type-0">type/0</a></li> <li title="version-0"><a href="os.html#version-0">version/0</a></li> </ul> </li> <li id="no" title="pg2 " expanded="false">pg2<ul> <li><a href="pg2.html"> Top of manual page </a></li> <li title="create-1"><a href="pg2.html#create-1">create/1</a></li> <li title="delete-1"><a href="pg2.html#delete-1">delete/1</a></li> <li title="get_closest_pid-1"><a href="pg2.html#get_closest_pid-1">get_closest_pid/1</a></li> <li title="get_members-1"><a href="pg2.html#get_members-1">get_members/1</a></li> <li title="get_local_members-1"><a href="pg2.html#get_local_members-1">get_local_members/1</a></li> <li title="join-2"><a href="pg2.html#join-2">join/2</a></li> <li title="leave-2"><a href="pg2.html#leave-2">leave/2</a></li> <li title="which_groups-0"><a href="pg2.html#which_groups-0">which_groups/0</a></li> <li title="start-0"><a href="pg2.html#start-0">start/0</a></li> <li title="start_link-0"><a href="pg2.html#start_link-0">start_link/0</a></li> </ul> </li> <li id="no" title="rpc " expanded="false">rpc<ul> <li><a href="rpc.html"> Top of manual page </a></li> <li title="call-4"><a href="rpc.html#call-4">call/4</a></li> <li title="call-5"><a href="rpc.html#call-5">call/5</a></li> <li title="block_call-4"><a href="rpc.html#block_call-4">block_call/4</a></li> <li title="block_call-5"><a href="rpc.html#block_call-5">block_call/5</a></li> <li title="async_call-4"><a href="rpc.html#async_call-4">async_call/4</a></li> <li title="yield-1"><a href="rpc.html#yield-1">yield/1</a></li> <li title="nb_yield-1"><a href="rpc.html#nb_yield-1">nb_yield/1</a></li> <li title="nb_yield-2"><a href="rpc.html#nb_yield-2">nb_yield/2</a></li> <li title="multicall-3"><a href="rpc.html#multicall-3">multicall/3</a></li> <li title="multicall-4"><a href="rpc.html#multicall-4">multicall/4</a></li> <li title="multicall-4"><a href="rpc.html#multicall-4">multicall/4</a></li> <li title="multicall-5"><a href="rpc.html#multicall-5">multicall/5</a></li> <li title="cast-4"><a href="rpc.html#cast-4">cast/4</a></li> <li title="eval_everywhere-3"><a href="rpc.html#eval_everywhere-3">eval_everywhere/3</a></li> <li title="eval_everywhere-4"><a href="rpc.html#eval_everywhere-4">eval_everywhere/4</a></li> <li title="abcast-2"><a href="rpc.html#abcast-2">abcast/2</a></li> <li title="abcast-3"><a href="rpc.html#abcast-3">abcast/3</a></li> <li title="sbcast-2"><a href="rpc.html#sbcast-2">sbcast/2</a></li> <li title="sbcast-3"><a href="rpc.html#sbcast-3">sbcast/3</a></li> <li title="server_call-4"><a href="rpc.html#server_call-4">server_call/4</a></li> <li title="multi_server_call-2"><a href="rpc.html#multi_server_call-2">multi_server_call/2</a></li> <li title="multi_server_call-3"><a href="rpc.html#multi_server_call-3">multi_server_call/3</a></li> <li title="safe_multi_server_call-2"><a href="rpc.html#safe_multi_server_call-2">safe_multi_server_call/2</a></li> <li title="safe_multi_server_call-3"><a href="rpc.html#safe_multi_server_call-3">safe_multi_server_call/3</a></li> <li title="parallel_eval-1"><a href="rpc.html#parallel_eval-1">parallel_eval/1</a></li> <li title="pmap-3"><a href="rpc.html#pmap-3">pmap/3</a></li> <li title="pinfo-1"><a href="rpc.html#pinfo-1">pinfo/1</a></li> <li title="pinfo-2"><a href="rpc.html#pinfo-2">pinfo/2</a></li> </ul> </li> <li id="no" title="seq_trace " expanded="false">seq_trace<ul> <li><a href="seq_trace.html"> Top of manual page </a></li> <li title="set_token-1"><a href="seq_trace.html#set_token-1">set_token/1</a></li> <li title="set_token-2"><a href="seq_trace.html#set_token-2">set_token/2</a></li> <li title="get_token-0"><a href="seq_trace.html#get_token-0">get_token/0</a></li> <li title="get_token-1"><a href="seq_trace.html#get_token-1">get_token/1</a></li> <li title="print-1"><a href="seq_trace.html#print-1">print/1</a></li> <li title="print-2"><a href="seq_trace.html#print-2">print/2</a></li> <li title="reset_trace-0"><a href="seq_trace.html#reset_trace-0">reset_trace/0</a></li> <li title="set_system_tracer-1"><a href="seq_trace.html#set_system_tracer-1">set_system_tracer/1</a></li> <li title="get_system_tracer-0"><a href="seq_trace.html#get_system_tracer-0">get_system_tracer/0</a></li> </ul> </li> <li title="user"><a href="user.html">user</a></li> <li id="no" title="wrap_log_reader " expanded="false">wrap_log_reader<ul> <li><a href="wrap_log_reader.html"> Top of manual page </a></li> <li title="chunk-1"><a href="wrap_log_reader.html#chunk-1">chunk/1</a></li> <li title="chunk-2"><a href="wrap_log_reader.html#chunk-2">chunk/2</a></li> <li title="close-1"><a href="wrap_log_reader.html#close-1">close/1</a></li> <li title="open-1"><a href="wrap_log_reader.html#open-1">open/1</a></li> <li title="open-2"><a href="wrap_log_reader.html#open-2">open/2</a></li> </ul> </li> <li title="zlib"><a href="zlib.html">zlib</a></li> <li title="app"><a href="app.html">app</a></li> <li title="config"><a href="config.html">config</a></li> <li id="no" title="packages " expanded="false">packages<ul> <li><a href="packages.html"> Top of manual page </a></li> <li title="-0"><a href="packages.html#-0">/0</a></li> </ul> </li> </ul> </div></div> <div id="content"> <div class="innertube"> <!-- refpage --><center><h1>inet_res</h1></center> <h3>MODULE</h3> <div class="REFBODY">inet_res</div> <h3>MODULE SUMMARY</h3> <div class="REFBODY">A Rudimentary DNS Client</div> <h3>DESCRIPTION</h3> <div class="REFBODY"><p> <p>Performs DNS name resolving towards recursive name servers</p> <p>See also <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','inet_cfg.html');"> ERTS User's Guide: Inet configuration </a></span> for more information on how to configure an Erlang runtime system for IP communication and how to enable this DNS client by defining <span class="code">'dns'</span> as a lookup method. It then acts as a backend for the resolving functions in <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html');">inet</a></span>.</p> <p>This DNS client can resolve DNS records even if it is not used for normal name resolving in the node.</p> <p>This is not a full-fledged resolver. It is just a DNS client that relies on asking trusted recursive nameservers.</p> </p></div> <h3><a name="id2329575">Name Resolving</a></h3> <div class="REFBODY"> <p>UDP queries are used unless resolver option <span class="code">usevc</span> is <span class="code">true</span>, which forces TCP queries. If the query is to large for UDP, TCP is used instead. For regular DNS queries 512 bytes is the size limit. When EDNS is enabled (resolver option <span class="code">edns</span> is set to the EDNS version i.e <span class="code">0</span> instead of <span class="code">false</span>), resolver option <span class="code">udp_payload_size</span> sets the limit. If a nameserver replies with the TC bit set (truncation), indicating the answer is incomplete, the query is retried to that nameserver using TCP. The resolver option <span class="code">udp_payload_size</span> also sets the advertised size for the max allowed reply size, if EDNS is enabled, otherwise the nameserver uses the limit 512 byte. If the reply is larger it gets truncated, forcing a TCP re-query.</p> <p>For UDP queries, the resolver options <span class="code">timeout</span> and <span class="code">retry</span> control retransmission. Each nameserver in the <span class="code">nameservers</span> list is tried with a timeout of <span class="code">timeout</span> / <span class="code">retry</span>. Then all nameservers are tried again doubling the timeout, for a total of <span class="code">retry</span> times.</p> <p>For queries that not use the <span class="code">search</span> list, if the query to all <span class="code">nameservers</span> results in <span class="code">{error,nxdomain}</span>or an empty answer, the same query is tried for the <span class="code">alt_nameservers</span>.</p> </div> <h3><a name="id2329674">DATA TYPES</a></h3> <div class="REFBODY"> <p>As defined in the module <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html');">inet</a></span>:</p> <div class="example"><pre> hostent() = #hostent{} posix() = some atom()s ip_address() = tuple of integers of arity 4 or 8</pre></div> <p>Resolver types:</p> <div class="example"><pre>These correspond to resolver options: res_option() = [ {alt_nameservers, [ nameserver() ]} | {edns, 0 | false} % Use EDNS | {inet6, bool()} % Return IPv6 addresses | {nameservers, [ nameserver() ]} % List of nameservers | {recurse, bool()} % Request server recursion | {retry, integer()} % UDP retries | {timeout, integer()} % UDP query timeout | {udp_payload_size, integer()} % EDNS payload size | {usevc, bool()} ] % Use TCP (Virtual Circuit) nameserver() = {ip_address(),Port} Port = integer(1..65535) res_error() = formerr | qfmterror | servfail | nxdomain | notimp | refused | badvers | timeout </pre></div> <p>DNS types:</p> <a name="dns_types"></a> <div class="example"><pre>dns_name() = string() with no adjacent dots rr_type() = a | aaaa | cname | gid | hinfo | ns | mb | md | mg | mf | minfo | mx | naptr | null | ptr | soa | spf | srv | txt | uid | uinfo | unspec | wks query_type() = axfr | mailb | maila | any | rr_type() dns_class() = in | chaos | hs | any dns_msg() = DnsMsg This is the start of a hiearchy of opaque data structures that can be examined with access functions in inet_dns that return lists of {Field,Value} tuples. The arity 2 functions just return the value for a given field. inet_dns:msg(DnsMsg) -> [ {header, dns_header()} | {qdlist, dns_query()} | {anlist, dns_rr()} | {nslist, dns_rr()} | {arlist, dns_rr()} ] inet_dns:msg(DnsMsg, header) -> dns_header() % for example inet_dns:msg(DnsMsg, Field) -> Value dhs_header() = DnsHeader inet_dns:header(DnsHeader) -> [ {id, integer()} | {qr, bool()} | {opcode, 'query' | iquery | status | integer()} | {aa, bool()} | {tc, bool()} | {rd, bool()} | {ra, bool()} | {pr, bool()} | {rcode, integer(0..16)} ] inet_dns:header(DnsHeader, Field) -> Value dns_query() = DnsQuery inet_dns:dns_query(DnsQuery) -> [ {domain, dns_name()} | {type, query_type()} | {class, dns_class()} ] inet_dns:dns_query(DnsQuery, Field) -> Value dns_rr() = DnsRr inet_dns:rr(DnsRr) -> DnsRrFields | DnsRrOptFields DnsRrFields = [ {domain, dns_name()} | {type, rr_type()} | {class, dns_class()} | {ttl, integer()} | {data, dns_data()} ] DnsRrOptFields = [ {domain, dns_name()} | {type, opt} | {udp_payload_size, integer()} | {ext_rcode, integer()} | {version, integer()} | {z, integer()} | {data, dns_data()} ] inet_dns:rr(DnsRr, Field) -> Value dns_data() = % for dns_type() [ dns_name() % ns, md, mf, cname, mb, mg, mr, ptr | ip_address(v4) % a | ip_address(v6) % aaaa | {MName,RName,Serial,Refresh,Retry,Expiry,Minimum} % soa | {ip_address(v4),Proto,BitMap} % wks | {CpuString,OsString} % hinfo | {RM,EM} % minfo | {Prio,dns_name()} % mx | {Prio,Weight,Port,dns_name()} % srv | {Order,Preference,Flags,Services,Regexp,dns_name()} % naptr | [ string() ] % txt, spf | binary() ] % null, integer() MName, RName = dns_name() Serial, Refresh, Retry, Expiry, Minimum = integer(), Proto = integer() BitMap = binary() CpuString, OsString = string() RM = EM = dns_name() Prio, Weight, Port = integer() Order, Preference = integer() Flags, Services = string(), Regexp = string(utf8) There is an info function for the types above: inet_dns:record_type(dns_msg()) -> msg; inet_dns:record_type(dns_header()) -> header; inet_dns:record_type(dns_query()) -> dns_query; inet_dns:record_type(dns_rr()) -> rr; inet_dns:record_type(_) -> undefined. So; inet_dns:(inet_dns:record_type(X))(X) will convert any of these data structures into a {Field,Value} list.</pre></div> </div> <h3>EXPORTS</h3> <p><a name="getbyname-2"><span class="bold_code">getbyname(Name, Type) -> {ok,hostent()} | {error,Reason}</span></a><br><a name="getbyname-3"><span class="bold_code">getbyname(Name, Type, Timeout) -> {ok,hostent()} | {error,Reason} </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Type = rr_type()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Resolve a DNS record of the given type for the given host, of class <span class="code">in</span>. On success returns a <span class="code">hostent()</span> record with <span class="code">dns_data()</span> elements in the address list field. </p><p> This function uses the resolver option <span class="code">search</span> that is a list of domain names. If the name to resolve contains no dots, it is prepended to each domain name in the search list, and they are tried in order. If the name contains dots, it is first tried as an absolute name and if that fails the search list is used. If the name has a trailing dot it is simply supposed to be an absolute name and the search list is not used. </p> </p></div> <p><a name="gethostbyaddr-1"><span class="bold_code">gethostbyaddr(Address) -> {ok,hostent()} | {error,Reason}</span></a><br><a name="gethostbyaddr-2"><span class="bold_code">gethostbyaddr(Address, Timeout) -> {ok,hostent()} | {error,Reason} </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Address = ip_address()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Backend functions used by <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html#gethostbyaddr-1');"> inet:gethostbyaddr/1 </a></span>. </p> </p></div> <p><a name="gethostbyname-1"><span class="bold_code">gethostbyname(Name) -> {ok,hostent()} | Reason}</span></a><br><a name="gethostbyname-2"><span class="bold_code">gethostbyname(Name, Family) -> {ok,hostent()} | {error,Reason}} </span></a><br><a name="gethostbyname-3"><span class="bold_code">gethostbyname(Name, Family, Timeout) -> {ok,hostent()} | {error,Reason} </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Backend functions used by <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html#gethostbyname-1');"> inet:gethostbyname/1,2 </a></span>. </p><p> This function uses the resolver option <span class="code">search</span> just like <span class="bold_code"><a href="#getbyname-2">getbyname/2,3</a></span>. </p><p> If the resolver option <span class="code">inet6</span> is <span class="code">true</span>, an IPv6 address is looked up, and if that fails the IPv4 address is looked up and returned on IPv6 mapped IPv4 format. </p> </p></div> <p><a name="lookup-3"><span class="bold_code">lookup(Name, Class, Type) -> [ dns_data() ] </span></a><br><a name="lookup-4"><span class="bold_code">lookup(Name, Class, Type, Opts) -> [ dns_data() ] </span></a><br><a name="lookup-5"><span class="bold_code">lookup(Name, Class, Type, Opts, Timeout) -> [ dns_data() ] </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name() | ip_address()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Type = rr_type()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Opts = res_option() | verbose</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Resolve the DNS data for the record of the given type and class for the given name. On success filters out the answer records with the correct <span class="code">Class</span> and <span class="code">Type</span> and returns a list of their data fields. So a lookup for type <span class="code">any</span> will give an empty answer since the answer records have specific types that are not <span class="code">any</span>. An empty answer as well as a failed lookup returns an empty list. </p><p> Calls <span class="bold_code"><a href="#resolve-3">resolve/2..4</a></span> with the same arguments and filters the result, so <span class="code">Opts</span> is explained there. </p> </p></div> <p><a name="resolve-3"><span class="bold_code">resolve(Name, Class, Type) -> {ok,dns_msg()} | Error </span></a><br><a name="resolve-4"><span class="bold_code">resolve(Name, Class, Type, Opts) -> {ok,dns_msg()} | Error </span></a><br><a name="resolve-5"><span class="bold_code">resolve(Name, Class, Type, Opts, Timeout) -> {ok,dns_msg()} | Error </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name() | ip_address()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Type = rr_type()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Opts = res_option() | verbose | atom()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Error = {error,Reason} | {error,{Reason,dns_msg()}}</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Resolve a DNS record of the given type and class for the given name. The returned <span class="code">dns_msg()</span> can be examined using access functions in <span class="code">inet_db</span> as described in <span class="bold_code"><a href="#dns_types">DNS types</a></span>. </p><p> If <span class="code">Name</span> is an <span class="code">ip_address()</span>, the domain name to query for is generated as the standard reverse ".IN-ADDR.ARPA." name for an IPv4 address, or the ".IP6.ARPA." name for an IPv6 address. In this case you most probably want to use <span class="code">Class = in</span> and <span class="code">Type = ptr</span> but it is not done automatically. </p><p> <span class="code">Opts</span> override the corresponding resolver options. If the option <span class="code">nameservers</span> is given, it is also assumed that it is the complete list of nameserves, so the resolver option <span class="code">alt_nameserves</span> is ignored. Of course, if that option is also given to this function, it is used. </p><p> The <span class="code">verbose</span> option (or rather <span class="code">{verbose,true}</span>), causes diagnostics printout through <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','io.html#format-3');">io:format/2</a></span> of queries, replies retransmissions, etc, similar to from utilities like <span class="code">dig</span>, <span class="code">nslookup</span> et.al. </p><p> If <span class="code">Opt</span> is an arbitrary atom it is interpreted as <span class="code">{Opt,true}</span> unless the atom string starts with <span class="code">"no"</span> making the interpretation <span class="code">{Opt,false}</span>. For example: <span class="code">usevc</span> is an alias for <span class="code">{usevc,true}</span>, and <span class="code">nousevc</span> an alias for <span class="code">{usevc,false}</span>. </p><p> The <span class="code">inet6</span> option currently has no effect on this function. You probably want to use <span class="code">Type = a | aaaa</span> instead. </p> </p></div> <h3><a name="id2330273">Examples</a></h3> <div class="REFBODY"> <p>Access functions example: how <span class="bold_code"><a href="#lookup-3">lookup/3</a></span> could have been implemented using <span class="bold_code"><a href="#resolve-3">resolve/3</a></span> from outside the module. </p> <div class="example"><pre> example_lookup(Name, Class, Type) -> case inet_res:resolve(Name, Class, Type) of {ok,Msg} -> [inet_dns:rr(RR, data) || RR <- inet_dns:msg(Msg, anlist), inet_dns:rr(RR, type) =:= Type, inet_dns:rr(RR, class) =:= Class]; {error,_} -> [] end.</pre></div> </div> <h3><a name="id2330309">Legacy Functions</a></h3> <div class="REFBODY"> <p>These have been deprecated due to the annoying double meaning of the nameservers/timeout argument, and because they had no decent place for a resolver options list.</p> </div> <h3>EXPORTS</h3> <p><a name="nslookup-3"><span class="bold_code">nslookup(Name, Class, Type) -> {ok,dns_msg()} | {error,Reason} </span></a><br><a name="nslookup-4"><span class="bold_code">nslookup(Name, Class, Type, Timeout) -> {ok,dns_msg()} | {error,Reason} </span></a><br><a name="nslookup-4"><span class="bold_code">nslookup(Name, Class, Type, Nameservers) -> {ok,dns_msg()} | {error,Reason} </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name() | ip_address()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Type = rr_type()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Nameservers = [ nameserver() ]</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Resolve a DNS record of the given type and class for the given name. </p> </p></div> <p><a name="nnslookup-4"><span class="bold_code">nnslookup(Name, Class, Type, Nameservers) -> {ok,dns_msg()} | {error,posix()} </span></a><br><a name="nnslookup-5"><span class="bold_code">nnslookup(Name, Class, Type, Nameservers, Timeout) -> {ok,dns_msg()} | {error,posix()} </span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Name = dns_name() | ip_address()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Type = rr_type()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Nameservers = [ nameserver() ]</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Timeout = integer() >= 0 | infinity</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Reason = posix() | res_error()</span><br> </div> </div> <div class="REFBODY"><p> <p>Resolve a DNS record of the given type and class for the given name. </p> </p></div> </div> <div class="footer"> <hr> <p>Copyright © 1997-2010 Ericsson AB. All Rights Reserved.</p> </div> </div> </div></body> </html>