1inet(3) Erlang Module Definition inet(3)
2
6 inet - Access to TCP/IP protocols.
7
9 This module provides access to TCP/IP protocols.
10 See also ERTS User's Guide: Inet Configuration for more information
12 about how to configure an Erlang runtime system for IP communication.
13 The following two Kernel configuration parameters affect the behavior
15 of all sockets opened on an Erlang node:
16 * inet_default_connect_options can contain a list of default options
18 used for all sockets returned when doing connect.
19 * inet_default_listen_options can contain a list of default options
21 used when issuing a listen call.
22 When accept is issued, the values of the listening socket options are
24 inherited. No such application variable is therefore needed for accept.
25 Using the Kernel configuration parameters above, one can set default
27 options for all TCP sockets on a node, but use this with care. Options
28 such as {delay_send,true} can be specified in this way. The following
29 is an example of starting an Erlang node with all sockets using delayed
30 send:
31 $ erl -sname test -kernel \
33 inet_default_connect_options '[{delay_send,true}]' \
34 inet_default_listen_options '[{delay_send,true}]'
35 Notice that default option {active, true} cannot be changed, for inter‐
37 nal reasons.
38 Addresses as inputs to functions can be either a string or a tuple. For
40 example, the IP address 150.236.20.73 can be passed to gethostbyaddr/1,
41 either as string "150.236.20.73" or as tuple {150, 236, 20, 73}.
42 IPv4 address examples:
44 Address ip_address()
46 ------- ------------
47 127.0.0.1 {127,0,0,1}
48 192.168.42.2 {192,168,42,2}
49 IPv6 address examples:
51 Address ip_address()
53 ------- ------------
54 ::1 {0,0,0,0,0,0,0,1}
55 ::192.168.42.2 {0,0,0,0,0,0,(192 bsl 8) bor 168,(42 bsl 8) bor 2}
56 ::FFFF:192.168.42.2
57 {0,0,0,0,0,16#FFFF,(192 bsl 8) bor 168,(42 bsl 8) bor 2}
58 3ffe:b80:1f8d:2:204:acff:fe17:bf38
59 {16#3ffe,16#b80,16#1f8d,16#2,16#204,16#acff,16#fe17,16#bf38}
60 fe80::204:acff:fe17:bf38
61 {16#fe80,0,0,0,16#204,16#acff,16#fe17,16#bf38}
62 Function parse_address/1 can be useful:
64 1> inet:parse_address("192.168.42.2").
66 {ok,{192,168,42,2}}
67 2> inet:parse_address("::FFFF:192.168.42.2").
68 {ok,{0,0,0,0,0,65535,49320,10754}}
69
71 Exported data types
72 hostent() =
73 #hostent{h_name = inet:hostname(),
74 h_aliases = [inet:hostname()],
75 h_addrtype = inet | inet6,
76 h_length = integer() >= 0,
77 h_addr_list = [inet:ip_address()]}
78 The record is defined in the Kernel include file "inet.hrl".
80 Add the following directive to the module:
82 -include_lib("kernel/include/inet.hrl").
84 hostname() = atom() | string()
86 ip_address() = ip4_address() | ip6_address()
88 ip4_address() = {0..255, 0..255, 0..255, 0..255}
90 ip6_address() =
92 {0..65535,
93 0..65535,
94 0..65535,
95 0..65535,
96 0..65535,
97 0..65535,
98 0..65535,
99 0..65535}
100 port_number() = 0..65535
102 family_address() =
104 inet_address() | inet6_address() | local_address()
105 A general address format on the form {Family, Destination} where
107 Family is an atom such as local and the format of Destination
108 depends on Family, and is a complete address (for example an IP
109 address including port number).
110 local_address() = {local, File :: binary() | string()}
112 This address family only works on Unix-like systems.
114 File is normally a file pathname in a local filesystem. It is
116 limited in length by the operating system, traditionally to 108
117 bytes.
118 A binary() is passed as is to the operating system, but a
120 string() is encoded according to the system filename encoding
121 mode.
122 Other addresses are possible, for example Linux implements "Ab‐
124 stract Addresses". See the documentation for Unix Domain Sockets
125 on your system, normally unix in manual section 7.
126 In most API functions where you can use this address family the
128 port number must be 0.
129 inet_backend() = {inet_backend, inet | socket}
131 Select the implementation backend for sockets. The current de‐
133 fault is inet which at the bottom uses inet_drv.c to call the
134 platform's socket API. The value socket instead at the bottom
135 uses the socket module and its NIF implementation.
136 This is a temporary option that will be ignored in a future re‐
138 lease.
139 socket_address() =
141 ip_address() | any | loopback | local_address()
142 socket_getopt() =
144 gen_sctp:option_name() |
145 gen_tcp:option_name() |
146 gen_udp:option_name()
147 socket_setopt() =
149 gen_sctp:option() | gen_tcp:option() | gen_udp:option()
150 socket_optval() =
152 gen_sctp:option_value() |
153 gen_tcp:option() |
154 gen_udp:option() |
155 gen_tcp:pktoptions_value()
156 returned_non_ip_address() =
158 {local, binary()} | {unspec, <<>>} | {undefined, any()}
159 Addresses besides ip_address() ones that are returned from
161 socket API functions. See in particular local_address(). The
162 unspec family corresponds to AF_UNSPEC and can occur if the
163 other side has no socket address. The undefined family can only
164 occur in the unlikely event of an address family that the VM
165 does not recognize.
166 ancillary_data() =
168 [{tos, byte()} | {tclass, byte()} | {ttl, byte()}]
169 Ancillary data received with the data packet, read with the
171 socket option pktoptions from a TCP socket, or to set in a call
172 to gen_udp:send/4 or gen_udp:send/5.
173 The value(s) correspond to the currently active socket options
175 recvtos, recvtclass and recvttl, or for a single send operation
176 the option(s) to override the currently active socket option(s).
177 posix() =
179 eaddrinuse | eaddrnotavail | eafnosupport | ealready |
180 econnaborted | econnrefused | econnreset | edestaddrreq |
181 ehostdown | ehostunreach | einprogress | eisconn | emsgsize |
182 enetdown | enetunreach | enopkg | enoprotoopt | enotconn |
183 enotty | enotsock | eproto | eprotonosupport | eprototype |
184 esocktnosupport | etimedout | ewouldblock | exbadport |
185 exbadseq |
186 file:posix()
187 An atom that is named from the POSIX error codes used in Unix,
189 and in the runtime libraries of most C compilers. See section
190 POSIX Error Codes.
191 socket()
193 See gen_tcp:type-socket and gen_udp:type-socket.
195 address_family() = inet | inet6 | local
197 socket_protocol() = tcp | udp | sctp
199 stat_option() =
201 recv_cnt | recv_max | recv_avg | recv_oct | recv_dvi |
202 send_cnt | send_max | send_avg | send_oct | send_pend
203
205 Internal data types
206 inet_address() =
207 {inet, {ip4_address() | any | loopback, port_number()}}
208 Warning:
210 This address format is for now experimental and for completeness
211 to make all address families have a {Family, Destination} repre‐
212 sentation.
213 inet6_address() =
216 {inet6, {ip6_address() | any | loopback, port_number()}}
217 Warning:
219 This address format is for now experimental and for completeness
220 to make all address families have a {Family, Destination} repre‐
221 sentation.
222 getifaddrs_ifopts() =
225 [Ifopt ::
226 {flags,
227 Flags ::
228 [up | broadcast | loopback | pointtopoint |
229 running | multicast]} |
230 {addr, Addr :: ip_address()} |
231 {netmask, Netmask :: ip_address()} |
232 {broadaddr, Broadaddr :: ip_address()} |
233 {dstaddr, Dstaddr :: ip_address()} |
234 {hwaddr, Hwaddr :: [byte()]}]
235 Interface address description list returned from getifaddrs/0,1
237 for a named interface, translated from the returned data of the
238 POSIX API function getaddrinfo().
239 Hwaddr is hardware dependent, for example, on Ethernet inter‐
241 faces it is the 6-byte Ethernet address (MAC address (EUI-48 ad‐
242 dress)).
243 The tuples {addr,Addr}, {netmask,Netmask}, and possibly {broad‐
245 addr,Broadaddr} or {dstaddr,Dstaddr} are repeated in the list if
246 the interface has got multiple addresses. An interface may have
247 multiple {flag,_} tuples for example if it has different flags
248 for different address families. Multiple {hwaddr,Hwaddr} tuples
249 is hard to say anything definite about, though. The tuple
250 {flag,Flags} is mandatory, all others are optional.
251 Do not rely too much on the order of Flags atoms or the Ifopt
253 tuples. There are however some rules:
254 * A {flag,_} tuple applies to all other tuples that follow.
256 * Immediately after {addr,_} follows {netmask,_}.
258 * Immediately thereafter may {broadaddr,_} follow if broadcast
260 is member of Flags, or {dstaddr,_} if pointtopoint is member
261 of Flags. Both {dstaddr,_} and {broadaddr,_} does not occur
262 for the same {addr,_}.
263 * Any {netmask,_}, {broadaddr,_}, or {dstaddr,_} tuples that
265 follow an {addr,Addr} tuple concerns the address Addr.
266 The tuple {hwaddr,_} is not returned on Solaris, as the hardware
268 address historically belongs to the link layer and it is not re‐
269 turned by the Solaris API function getaddrinfo().
270 Warning:
272 On Windows, the data is fetched from different OS API functions,
273 so the Netmask and Broadaddr values may be calculated, just as
274 some Flags values.
275
278 close(Socket) -> ok
279 Types:
281 Socket = socket()
283 Closes a socket of any type.
285 cancel_monitor(MRef) -> boolean()
287 Types:
289 MRef = reference()
291 If MRef is a reference that the calling process obtained by
293 calling monitor/1, this monitor is turned off. If the monitoring
294 is already turned off, nothing happens.
295 The returned value is one of the following:
297 true:
299 The monitor was found and removed. In this case, no 'DOWN'
300 message corresponding to this monitor has been delivered and
301 will not be delivered.
302 false:
304 The monitor was not found and could not be removed. This
305 probably because a 'DOWN' message corresponding to this mon‐
306 itor has already been placed in the caller message queue.
307 Failure: It is an error if MRef refers to a monitor started by
309 another process.
310 format_error(Reason) -> string()
312 Types:
314 Reason = posix() | system_limit
316 Returns a diagnostic error string. For possible POSIX values and
318 corresponding strings, see section POSIX Error Codes.
319 get_rc() ->
321 [{Par :: atom(), Val :: any()} |
322 {Par :: atom(), Val1 :: any(), Val2 :: any()}]
323 Returns the state of the Inet configuration database in form of
325 a list of recorded configuration parameters. For more informa‐
326 tion, see ERTS User's Guide: Inet Configuration.
327 Only actual parameters with other than default values are re‐
329 turned, for example not directives that specify other sources
330 for configuration parameters nor directives that clear parame‐
331 ters.
332 getaddr(Host, Family) -> {ok, Address} | {error, posix()}
334 Types:
336 Host = ip_address() | hostname()
338 Family = address_family()
339 Address = ip_address()
340 Returns the IP address for Host as a tuple of integers. Host can
342 be an IP address, a single hostname, or a fully qualified host‐
343 name.
344 getaddrs(Host, Family) -> {ok, Addresses} | {error, posix()}
346 Types:
348 Host = ip_address() | hostname()
350 Family = address_family()
351 Addresses = [ip_address()]
352 Returns a list of all IP addresses for Host. Host can be an IP
354 address, a single hostname, or a fully qualified hostname.
355 gethostbyaddr(Address) -> {ok, Hostent} | {error, posix()}
357 Types:
359 Address = string() | ip_address()
361 Hostent = hostent()
362 Returns a hostent record for the host with the specified ad‐
364 dress.
365 gethostbyname(Hostname) -> {ok, Hostent} | {error, posix()}
367 Types:
369 Hostname = hostname()
371 Hostent = hostent()
372 Returns a hostent record for the host with the specified host‐
374 name.
375 If resolver option inet6 is true, an IPv6 address is looked up.
377 gethostbyname(Hostname, Family) ->
379 {ok, Hostent} | {error, posix()}
380 Types:
382 Hostname = hostname()
384 Family = address_family()
385 Hostent = hostent()
386 Returns a hostent record for the host with the specified name,
388 restricted to the specified address family.
389 gethostname() -> {ok, Hostname}
391 Types:
393 Hostname = string()
395 Returns the local hostname. Never fails.
397 getifaddrs() ->
399 {ok,
400 [{Ifname :: string(),
401 Ifopts :: getifaddrs_ifopts()}]} |
402 {error, posix()}
403 Returns a list of 2-tuples containing interface names and the
405 interfaces' addresses. Ifname is a Unicode string and Ifopts is
406 a list of interface address description tuples.
407 The interface address description tuples are documented under
409 the type of the Ifopts value.
410 getifaddrs(Opts) -> {ok, [{Ifname, Ifopts}]} | {error, Posix}
412 Types:
414 Opts = [{netns, Namespace}]
416 Namespace = file:filename_all()
417 Ifname = string()
418 Ifopts = getifaddrs_ifopts()
419 Posix = posix()
420 The same as getifaddrs/0 but the Option {netns, Namespace} sets
422 a network namespace for the OS call, on platforms that supports
423 that feature.
424 See the socket option {netns, Namespace} under setopts/2.
426 getopts(Socket, Options) -> {ok, OptionValues} | {error, posix()}
428 Types:
430 Socket = socket()
432 Options = [socket_getopt()]
433 OptionValues = [socket_optval()]
434 Gets one or more options for a socket. For a list of available
436 inet options, see setopts/2. See also the descriptions for the
437 protocol specific types referenced by socket_optval().
438 The number of elements in the returned OptionValues list does
440 not necessarily correspond to the number of options asked for.
441 If the operating system fails to support an option, it is left
442 out in the returned list. An error tuple is returned only when
443 getting options for the socket is impossible (that is, the
444 socket is closed or the buffer size in a raw request is too
445 large). This behavior is kept for backward compatibility rea‐
446 sons.
447 A raw option request RawOptReq = {raw, Protocol, OptionNum, Val‐
449 ueSpec} can be used to get information about socket options not
450 (explicitly) supported by the emulator. The use of raw socket
451 options makes the code non-portable, but allows the Erlang pro‐
452 grammer to take advantage of unusual features present on a par‐
453 ticular platform.
454 RawOptReq consists of tag raw followed by the protocol level,
456 the option number, and either a binary or the size, in bytes, of
457 the buffer in which the option value is to be stored. A binary
458 is to be used when the underlying getsockopt requires input in
459 the argument field. In this case, the binary size is to corre‐
460 spond to the required buffer size of the return value. The sup‐
461 plied values in a RawOptReq correspond to the second, third, and
462 fourth/fifth parameters to the getsockopt call in the C socket
463 API. The value stored in the buffer is returned as a binary Val‐
464 ueBin, where all values are coded in the native endianness.
465 Asking for and inspecting raw socket options require low-level
467 information about the current operating system and TCP stack.
468 Example:
470 Consider a Linux machine where option TCP_INFO can be used to
472 collect TCP statistics for a socket. Assume you are interested
473 in field tcpi_sacked of struct tcp_info filled in when asking
474 for TCP_INFO. To be able to access this information, you need to
475 know the following:
476 * The numeric value of protocol level IPPROTO_TCP
478 * The numeric value of option TCP_INFO
480 * The size of struct tcp_info
482 * The size and offset of the specific field
484 By inspecting the headers or writing a small C program, it is
486 found that IPPROTO_TCP is 6, TCP_INFO is 11, the structure size
487 is 92 (bytes), the offset of tcpi_sacked is 28 bytes, and the
488 value is a 32-bit integer. The following code can be used to re‐
489 trieve the value:
490 get_tcpi_sacked(Sock) ->
492 {ok,[{raw,_,_,Info}]} = inet:getopts(Sock,[{raw,6,11,92}]),
493 <<_:28/binary,TcpiSacked:32/native,_/binary>> = Info,
494 TcpiSacked.
495 Preferably, you would check the machine type, the operating sys‐
497 tem, and the Kernel version before executing anything similar to
498 this code.
499 getstat(Socket) -> {ok, OptionValues} | {error, posix()}
501 getstat(Socket, Options) -> {ok, OptionValues} | {error, posix()}
503 Types:
505 Socket = socket()
507 Options = [stat_option()]
508 OptionValues = [{stat_option(), integer()}]
509 stat_option() =
510 recv_cnt | recv_max | recv_avg | recv_oct | recv_dvi |
511 send_cnt | send_max | send_avg | send_oct | send_pend
512 Gets one or more statistic options for a socket.
514 getstat(Socket) is equivalent to getstat(Socket, [recv_avg,
516 recv_cnt, recv_dvi, recv_max, recv_oct, send_avg, send_cnt,
517 send_pend, send_max, send_oct]).
518 The following options are available:
520 recv_avg:
522 Average size of packets, in bytes, received by the socket.
523 recv_cnt:
525 Number of packets received by the socket.
526 recv_dvi:
528 Average packet size deviation, in bytes, received by the
529 socket.
530 recv_max:
532 Size of the largest packet, in bytes, received by the
533 socket.
534 recv_oct:
536 Number of bytes received by the socket.
537 send_avg:
539 Average size of packets, in bytes, sent from the socket.
540 send_cnt:
542 Number of packets sent from the socket.
543 send_pend:
545 Number of bytes waiting to be sent by the socket.
546 send_max:
548 Size of the largest packet, in bytes, sent from the socket.
549 send_oct:
551 Number of bytes sent from the socket.
552 i() -> ok
554 i(Proto :: socket_protocol()) -> ok
556 i(X1 :: socket_protocol(), Fs :: [atom()]) -> ok
558 Lists all TCP, UDP and SCTP sockets, including those that the
560 Erlang runtime system uses as well as those created by the ap‐
561 plication.
562 The following options are available:
564 port:
566 The internal index of the port.
567 module:
569 The callback module of the socket.
570 recv:
572 Number of bytes received by the socket.
573 sent:
575 Number of bytes sent from the socket.
576 owner:
578 The socket owner process.
579 local_address:
581 The local address of the socket.
582 foreign_address:
584 The address and port of the other end of the connection.
585 state:
587 The connection state.
588 type:
590 STREAM or DGRAM or SEQPACKET.
591 info(Socket) -> Info
593 Types:
595 Socket = socket()
597 Info = term()
598 Produces a term containing miscellaneous information about a
600 socket.
601 monitor(Socket) -> reference()
603 Types:
605 Socket = socket()
607 Start monitor the socket Socket.
609 If the monitored socket does not exist or when the monitor is
611 triggered, a 'DOWN' message is sent that has the following pat‐
612 tern:
613 {'DOWN', MonitorRef, Type, Object, Info}
615 MonitorRef:
618 The identity of the socket.
619 Type:
621 The type of socket, can be one of the following atoms: port
622 or socket.
623 Object:
625 The monitored entity, the socket, which triggered the event.
626 Info:
628 Either the termination reason of the socket or nosock
629 (socket Socket did not exist at the time of monitor cre‐
630 ation).
631 Making several calls to inet:monitor/1 for the same Socket is
633 not an error; it results in as many independent monitoring in‐
634 stances.
635 is_ip_address(IPAddress) -> boolean()
637 Types:
639 IPAddress = ip_address() | term()
641 Tests if IPAddress is an ip_address() and returns true if so,
643 otherwise false.
644 is_ipv4_address(IPv4Address) -> boolean()
646 Types:
648 IPv4Address = ip4_address() | term()
650 Tests if IPAddress is an ip4_address() and returns true if so,
652 otherwise false.
653 is_ipv6_address(IPv6Address) -> boolean()
655 Types:
657 IPv6Address = ip6_address() | term()
659 Tests if IPAddress is an ip6_address() and returns true if so,
661 otherwise false.
662 ntoa(IpAddress) -> Address | {error, einval}
664 Types:
666 Address = string()
668 IpAddress = ip_address()
669 Parses an ip_address() and returns an IPv4 or IPv6 address
671 string.
672 parse_address(Address) -> {ok, IPAddress} | {error, einval}
674 Types:
676 Address = string()
678 IPAddress = ip_address()
679 Parses an IPv4 or IPv6 address string and returns an ip4_ad‐
681 dress() or ip6_address(). Accepts a shortened IPv4 address
682 string.
683 parse_ipv4_address(Address) -> {ok, IPv4Address} | {error, einval}
685 Types:
687 Address = string()
689 IPv4Address = ip4_address()
690 Parses an IPv4 address string and returns an ip4_address(). Ac‐
692 cepts a shortened IPv4 address string.
693 parse_ipv4strict_address(Address) ->
695 {ok, IPv4Address} | {error, einval}
696 Types:
698 Address = string()
700 IPv4Address = ip4_address()
701 Parses an IPv4 address string containing four fields, that is,
703 not shortened, and returns an ip4_address().
704 parse_ipv6_address(Address) -> {ok, IPv6Address} | {error, einval}
706 Types:
708 Address = string()
710 IPv6Address = ip6_address()
711 Parses an IPv6 address string and returns an ip6_address(). If
713 an IPv4 address string is specified, an IPv4-mapped IPv6 address
714 is returned.
715 parse_ipv6strict_address(Address) ->
717 {ok, IPv6Address} | {error, einval}
718 Types:
720 Address = string()
722 IPv6Address = ip6_address()
723 Parses an IPv6 address string and returns an ip6_address(). Does
725 not accept IPv4 addresses.
726 ipv4_mapped_ipv6_address(X1 :: ip_address()) -> ip_address()
728 Convert an IPv4 address to an IPv4-mapped IPv6 address or the
730 reverse. When converting from an IPv6 address all but the 2 low
731 words are ignored so this function also works on some other
732 types of addresses than IPv4-mapped.
733 parse_strict_address(Address) -> {ok, IPAddress} | {error, einval}
735 Types:
737 Address = string()
739 IPAddress = ip_address()
740 Parses an IPv4 or IPv6 address string and returns an ip4_ad‐
742 dress() or ip6_address(). Does not accept a shortened IPv4 ad‐
743 dress string.
744 peername(Socket :: socket()) ->
746 {ok,
747 {ip_address(), port_number()} |
748 returned_non_ip_address()} |
749 {error, posix()}
750 Returns the address and port for the other end of a connection.
752 Notice that for SCTP sockets, this function returns only one of
754 the peer addresses of the socket. Function peernames/1,2 returns
755 all.
756 peernames(Socket :: socket()) ->
758 {ok,
759 [{ip_address(), port_number()} |
760 returned_non_ip_address()]} |
761 {error, posix()}
762 Equivalent to peernames(Socket, 0).
764 Notice that the behavior of this function for an SCTP one-to-
766 many style socket is not defined by the SCTP Sockets API Exten‐
767 sions.
768 peernames(Socket, Assoc) ->
770 {ok, [{Address, Port}]} | {error, posix()}
771 Types:
773 Socket = socket()
775 Assoc = #sctp_assoc_change{} | gen_sctp:assoc_id()
776 Address = ip_address()
777 Port = integer() >= 0
778 Returns a list of all address/port number pairs for the other
780 end of an association Assoc of a socket.
781 This function can return multiple addresses for multihomed sock‐
783 ets, such as SCTP sockets. For other sockets it returns a one-
784 element list.
785 Notice that parameter Assoc is by the SCTP Sockets API Exten‐
787 sions defined to be ignored for one-to-one style sockets. What
788 the special value 0 means, hence its behavior for one-to-many
789 style sockets, is unfortunately undefined.
790 port(Socket) -> {ok, Port} | {error, any()}
792 Types:
794 Socket = socket()
796 Port = port_number()
797 Returns the local port number for a socket.
799 setopts(Socket, Options) -> ok | {error, posix()}
801 Types:
803 Socket = socket()
805 Options = [socket_setopt()]
806 Sets one or more options for a socket.
808 The following options are available:
810 {active, true | false | once | N}:
812 If the value is true, which is the default, everything re‐
813 ceived from the socket is sent as messages to the receiving
814 process.
815 If the value is false (passive mode), the process must ex‐
817 plicitly receive incoming data by calling gen_tcp:recv/2,3,
818 gen_udp:recv/2,3, or gen_sctp:recv/1,2 (depending on the
819 type of socket).
820 If the value is once ({active, once}), one data message from
822 the socket is sent to the process. To receive one more mes‐
823 sage, setopts/2 must be called again with option {active,
824 once}.
825 If the value is an integer N in the range -32768 to 32767
827 (inclusive), the value is added to the socket's count of
828 data messages sent to the controlling process. A socket's
829 default message count is 0. If a negative value is speci‐
830 fied, and its magnitude is equal to or greater than the
831 socket's current message count, the socket's message count
832 is set to 0. Once the socket's message count reaches 0, ei‐
833 ther because of sending received data messages to the
834 process or by being explicitly set, the process is then no‐
835 tified by a special message, specific to the type of socket,
836 that the socket has entered passive mode. Once the socket
837 enters passive mode, to receive more messages setopts/2 must
838 be called again to set the socket back into an active mode.
839 When using {active, once} or {active, N}, the socket changes
841 behavior automatically when data is received. This can be
842 confusing in combination with connection-oriented sockets
843 (that is, gen_tcp), as a socket with {active, false} behav‐
844 ior reports closing differently than a socket with {active,
845 true} behavior. To simplify programming, a socket where the
846 peer closed, and this is detected while in {active, false}
847 mode, still generates message {tcp_closed,Socket} when set
848 to {active, once}, {active, true}, or {active, N} mode. It
849 is therefore safe to assume that message
850 {tcp_closed,Socket}, possibly followed by socket port termi‐
851 nation (depending on option exit_on_close) eventually ap‐
852 pears when a socket changes back and forth between {active,
853 true} and {active, false} mode. However, when peer closing
854 is detected it is all up to the underlying TCP/IP stack and
855 protocol.
856 Notice that {active, true} mode provides no flow control; a
858 fast sender can easily overflow the receiver with incoming
859 messages. The same is true for {active, N} mode, while the
860 message count is greater than zero.
861 Use active mode only if your high-level protocol provides
863 its own flow control (for example, acknowledging received
864 messages) or the amount of data exchanged is small. {active,
865 false} mode, use of the {active, once} mode, or {active, N}
866 mode with values of N appropriate for the application pro‐
867 vides flow control. The other side cannot send faster than
868 the receiver can read.
869 {broadcast, Boolean} (UDP sockets):
871 Enables/disables permission to send broadcasts.
872 {buffer, Size}:
874 The size of the user-level buffer used by the driver. Not to
875 be confused with options sndbuf and recbuf, which correspond
876 to the Kernel socket buffers. For TCP it is recommended to
877 have val(buffer) >= val(recbuf) to avoid performance issues
878 because of unnecessary copying. For UDP the same recommenda‐
879 tion applies, but the max should not be larger than the MTU
880 of the network path. val(buffer) is automatically set to the
881 above maximum when recbuf is set. However, as the size set
882 for recbuf usually become larger, you are encouraged to use
883 getopts/2 to analyze the behavior of your operating system.
884 Note that this is also the maximum amount of data that can
886 be received from a single recv call. If you are using higher
887 than normal MTU consider setting buffer higher.
888 {delay_send, Boolean}:
890 Normally, when an Erlang process sends to a socket, the
891 driver tries to send the data immediately. If that fails,
892 the driver uses any means available to queue up the message
893 to be sent whenever the operating system says it can handle
894 it. Setting {delay_send, true} makes all messages queue up.
895 The messages sent to the network are then larger but fewer.
896 The option affects the scheduling of send requests versus
897 Erlang processes instead of changing any real property of
898 the socket. The option is implementation-specific. Defaults
899 to false.
900 {deliver, port | term}:
902 When {active, true}, data is delivered on the form port :
903 {S, {data, [H1,..Hsz | Data]}} or term : {tcp, S, [H1..Hsz |
904 Data]}.
905 {dontroute, Boolean}:
907 Enables/disables routing bypass for outgoing messages.
908 {exit_on_close, Boolean}:
910 This option is set to true by default.
911 The only reason to set it to false is if you want to con‐
913 tinue sending data to the socket after a close is detected,
914 for example, if the peer uses gen_tcp:shutdown/2 to shut
915 down the write side.
916 {header, Size}:
918 This option is only meaningful if option binary was speci‐
919 fied when the socket was created. If option header is speci‐
920 fied, the first Size number bytes of data received from the
921 socket are elements of a list, and the remaining data is a
922 binary specified as the tail of the same list. For example,
923 if Size == 2, the data received matches [Byte1,Byte2|Bi‐
924 nary].
925 {high_msgq_watermark, Size}:
927 The socket message queue is set to a busy state when the
928 amount of data on the message queue reaches this limit. No‐
929 tice that this limit only concerns data that has not yet
930 reached the ERTS internal socket implementation. Defaults to
931 8 kB.
932 Senders of data to the socket are suspended if either the
934 socket message queue is busy or the socket itself is busy.
935 For more information, see options low_msgq_watermark,
937 high_watermark, and low_watermark.
938 Notice that distribution sockets disable the use of
940 high_msgq_watermark and low_msgq_watermark. Instead use the
941 distribution buffer busy limit, which is a similar feature.
942 {high_watermark, Size} (TCP/IP sockets):
944 The socket is set to a busy state when the amount of data
945 queued internally by the ERTS socket implementation reaches
946 this limit. Defaults to 8 kB.
947 Senders of data to the socket are suspended if either the
949 socket message queue is busy or the socket itself is busy.
950 For more information, see options low_watermark,
952 high_msgq_watermark, and low_msqg_watermark.
953 {ipv6_v6only, Boolean}:
955 Restricts the socket to use only IPv6, prohibiting any IPv4
956 connections. This is only applicable for IPv6 sockets (op‐
957 tion inet6).
958 On most platforms this option must be set on the socket be‐
960 fore associating it to an address. It is therefore only rea‐
961 sonable to specify it when creating the socket and not to
962 use it when calling function (setopts/2) containing this de‐
963 scription.
964 The behavior of a socket with this option set to true is the
966 only portable one. The original idea when IPv6 was new of
967 using IPv6 for all traffic is now not recommended by FreeBSD
968 (you can use {ipv6_v6only,false} to override the recommended
969 system default value), forbidden by OpenBSD (the supported
970 GENERIC kernel), and impossible on Windows (which has sepa‐
971 rate IPv4 and IPv6 protocol stacks). Most Linux distros
972 still have a system default value of false. This policy
973 shift among operating systems to separate IPv6 from IPv4
974 traffic has evolved, as it gradually proved hard and compli‐
975 cated to get a dual stack implementation correct and secure.
976 On some platforms, the only allowed value for this option is
978 true, for example, OpenBSD and Windows. Trying to set this
979 option to false, when creating the socket, fails in this
980 case.
981 Setting this option on platforms where it does not exist is
983 ignored. Getting this option with getopts/2 returns no
984 value, that is, the returned list does not contain an
985 {ipv6_v6only,_} tuple. On Windows, the option does not ex‐
986 ist, but it is emulated as a read-only option with value
987 true.
988 Therefore, setting this option to true when creating a
990 socket never fails, except possibly on a platform where you
991 have customized the kernel to only allow false, which can be
992 doable (but awkward) on, for example, OpenBSD.
993 If you read back the option value using getopts/2 and get no
995 value, the option does not exist in the host operating sys‐
996 tem. The behavior of both an IPv6 and an IPv4 socket listen‐
997 ing on the same port, and for an IPv6 socket getting IPv4
998 traffic is then no longer predictable.
999 {keepalive, Boolean}(TCP/IP sockets):
1001 Enables/disables periodic transmission on a connected socket
1002 when no other data is exchanged. If the other end does not
1003 respond, the connection is considered broken and an error
1004 message is sent to the controlling process. Defaults to
1005 false.
1006 {linger, {true|false, Seconds}}:
1008 Determines the time-out, in seconds, for flushing unsent
1009 data in the close/1 socket call.
1010 The first component is if linger is enabled, the second com‐
1012 ponent is the flushing time-out, in seconds. There are 3 al‐
1013 ternatives:
1014 {false, _}:
1016 close/1 or shutdown/2 returns immediately, not waiting for
1017 data to be flushed, with closing happening in the back‐
1018 ground.
1019 {true, 0}:
1021 Aborts the connection when it is closed. Discards any data
1022 still remaining in the send buffers and sends RST to the
1023 peer.
1024 This avoids TCP's TIME_WAIT state, but leaves open the
1026 possibility that another "incarnation" of this connection
1027 being created.
1028 {true, Time} when Time > 0:
1030 close/1 or shutdown/2 will not return until all queued
1031 messages for the socket have been successfully sent or the
1032 linger timeout (Time) has been reached.
1033 {low_msgq_watermark, Size}:
1035 If the socket message queue is in a busy state, the socket
1036 message queue is set in a not busy state when the amount of
1037 data queued in the message queue falls below this limit. No‐
1038 tice that this limit only concerns data that has not yet
1039 reached the ERTS internal socket implementation. Defaults to
1040 4 kB.
1041 Senders that are suspended because of either a busy message
1043 queue or a busy socket are resumed when the socket message
1044 queue and the socket are not busy.
1045 For more information, see options high_msgq_watermark,
1047 high_watermark, and low_watermark.
1048 Notice that distribution sockets disable the use of
1050 high_msgq_watermark and low_msgq_watermark. Instead they use
1051 the distribution buffer busy limit, which is a similar fea‐
1052 ture.
1053 {low_watermark, Size} (TCP/IP sockets):
1055 If the socket is in a busy state, the socket is set in a not
1056 busy state when the amount of data queued internally by the
1057 ERTS socket implementation falls below this limit. Defaults
1058 to 4 kB.
1059 Senders that are suspended because of a busy message queue
1061 or a busy socket are resumed when the socket message queue
1062 and the socket are not busy.
1063 For more information, see options high_watermark,
1065 high_msgq_watermark, and low_msgq_watermark.
1066 {mode, Mode :: binary | list}:
1068 Received Packet is delivered as defined by Mode.
1069 {netns, Namespace :: file:filename_all()}:
1071 Sets a network namespace for the socket. Parameter Namespace
1072 is a filename defining the namespace, for example,
1073 "/var/run/netns/example", typically created by command ip
1074 netns add example. This option must be used in a function
1075 call that creates a socket, that is, gen_tcp:connect/3,4,
1076 gen_tcp:listen/2, gen_udp:open/1,2 or gen_sctp:open/0,1,2,
1077 and also getifaddrs/1.
1078 This option uses the Linux-specific syscall setns(), such as
1080 in Linux kernel 3.0 or later, and therefore only exists when
1081 the runtime system is compiled for such an operating system.
1082 The virtual machine also needs elevated privileges, either
1084 running as superuser or (for Linux) having capability
1085 CAP_SYS_ADMIN according to the documentation for setns(2).
1086 However, during testing also CAP_SYS_PTRACE and
1087 CAP_DAC_READ_SEARCH have proven to be necessary.
1088 Example:
1090 setcap cap_sys_admin,cap_sys_ptrace,cap_dac_read_search+epi beam.smp
1092 Notice that the filesystem containing the virtual machine
1094 executable (beam.smp in the example) must be local, mounted
1095 without flag nosetuid, support extended attributes, and the
1096 kernel must support file capabilities. All this runs out of
1097 the box on at least Ubuntu 12.04 LTS, except that SCTP sock‐
1098 ets appear to not support network namespaces.
1099 Namespace is a filename and is encoded and decoded as dis‐
1101 cussed in module file, with the following exceptions:
1102 * Emulator flag +fnu is ignored.
1104 * getopts/2 for this option returns a binary for the file‐
1106 name if the stored filename cannot be decoded. This is
1107 only to occur if you set the option using a binary that
1108 cannot be decoded with the emulator's filename encoding:
1109 file:native_name_encoding/0.
1110 {bind_to_device, Ifname :: binary()}:
1112 Binds a socket to a specific network interface. This option
1113 must be used in a function call that creates a socket, that
1114 is, gen_tcp:connect/3,4, gen_tcp:listen/2, gen_udp:open/1,2,
1115 or gen_sctp:open/0,1,2.
1116 Unlike getifaddrs/0, Ifname is encoded a binary. In the un‐
1118 likely case that a system is using non-7-bit-ASCII charac‐
1119 ters in network device names, special care has to be taken
1120 when encoding this argument.
1121 This option uses the Linux-specific socket option SO_BIND‐
1123 TODEVICE, such as in Linux kernel 2.0.30 or later, and
1124 therefore only exists when the runtime system is compiled
1125 for such an operating system.
1126 Before Linux 3.8, this socket option could be set, but could
1128 not retrieved with getopts/2. Since Linux 3.8, it is read‐
1129 able.
1130 The virtual machine also needs elevated privileges, either
1132 running as superuser or (for Linux) having capability
1133 CAP_NET_RAW.
1134 The primary use case for this option is to bind sockets into
1136 Linux VRF instances.
1137 list:
1139 Received Packet is delivered as a list.
1140 binary:
1142 Received Packet is delivered as a binary.
1143 {nodelay, Boolean}(TCP/IP sockets):
1145 If Boolean == true, option TCP_NODELAY is turned on for the
1146 socket, which means that also small amounts of data are sent
1147 immediately.
1148 This option is not supported for domain = local, but if
1150 inet_backend =/= socket this error will be ignored.
1151 {nopush, Boolean}(TCP/IP sockets):
1153 This translates to TCP_NOPUSH on BSD and to TCP_CORK on
1154 Linux.
1155 If Boolean == true, the corresponding option is turned on
1157 for the socket, which means that small amounts of data are
1158 accumulated until a full MSS-worth of data is available or
1159 this option is turned off.
1160 Note that while TCP_NOPUSH socket option is available on
1162 OSX, its semantics is very different (e.g., unsetting it
1163 does not cause immediate send of accumulated data). Hence,
1164 nopush option is intentionally ignored on OSX.
1165 {packet, PacketType}(TCP/IP sockets):
1167 Defines the type of packets to use for a socket. Possible
1168 values:
1169 raw | 0:
1171 No packaging is done.
1172 1 | 2 | 4:
1174 Packets consist of a header specifying the number of bytes
1175 in the packet, followed by that number of bytes. The
1176 header length can be one, two, or four bytes, and contain‐
1177 ing an unsigned integer in big-endian byte order. Each
1178 send operation generates the header, and the header is
1179 stripped off on each receive operation.
1180 The 4-byte header is limited to 2Gb.
1182 asn1 | cdr | sunrm | fcgi | tpkt | line:
1184 These packet types only have effect on receiving. When
1185 sending a packet, it is the responsibility of the applica‐
1186 tion to supply a correct header. On receiving, however,
1187 one message is sent to the controlling process for each
1188 complete packet received, and, similarly, each call to
1189 gen_tcp:recv/2,3 returns one complete packet. The header
1190 is not stripped off.
1191 The meanings of the packet types are as follows:
1193 * asn1 - ASN.1 BER
1195 * sunrm - Sun's RPC encoding
1197 * cdr - CORBA (GIOP 1.1)
1199 * fcgi - Fast CGI
1201 * tpkt - TPKT format [RFC1006]
1203 * line - Line mode, a packet is a line-terminated with
1205 newline, lines longer than the receive buffer are trun‐
1206 cated
1207 http | http_bin:
1209 The Hypertext Transfer Protocol. The packets are returned
1210 with the format according to HttpPacket described in er‐
1211 lang:decode_packet/3 in ERTS. A socket in passive mode re‐
1212 turns {ok, HttpPacket} from gen_tcp:recv while an active
1213 socket sends messages like {http, Socket, HttpPacket}.
1214 httph | httph_bin:
1216 These two types are often not needed, as the socket auto‐
1217 matically switches from http/http_bin to httph/httph_bin
1218 internally after the first line is read. However, there
1219 can be occasions when they are useful, such as parsing
1220 trailers from chunked encoding.
1221 {packet_size, Integer}(TCP/IP sockets):
1223 Sets the maximum allowed length of the packet body. If the
1224 packet header indicates that the length of the packet is
1225 longer than the maximum allowed length, the packet is con‐
1226 sidered invalid. The same occurs if the packet header is too
1227 large for the socket receive buffer.
1228 For line-oriented protocols (line, http*), option
1230 packet_size also guarantees that lines up to the indicated
1231 length are accepted and not considered invalid because of
1232 internal buffer limitations.
1233 {line_delimiter, Char}(TCP/IP sockets):
1235 Sets the line delimiting character for line-oriented proto‐
1236 cols (line). Defaults to $\n.
1237 {raw, Protocol, OptionNum, ValueBin}:
1239 See below.
1240 {read_packets, Integer}(UDP sockets):
1242 Sets the maximum number of UDP packets to read without in‐
1243 tervention from the socket when data is available. When this
1244 many packets have been read and delivered to the destination
1245 process, new packets are not read until a new notification
1246 of available data has arrived. Defaults to 5. If this param‐
1247 eter is set too high, the system can become unresponsive be‐
1248 cause of UDP packet flooding.
1249 {recbuf, Size}:
1251 The minimum size of the receive buffer to use for the
1252 socket. You are encouraged to use getopts/2 to retrieve the
1253 size set by your operating system.
1254 {recvtclass, Boolean}:
1256 If set to true activates returning the received TCLASS value
1257 on platforms that implements the protocol IPPROTO_IPV6 op‐
1258 tion IPV6_RECVTCLASS or IPV6_2292RECVTCLASS for the socket.
1259 The value is returned as a {tclass,TCLASS} tuple regardless
1260 of if the platform returns an IPV6_TCLASS or an IPV6_RECVT‐
1261 CLASS CMSG value.
1262 For packet oriented sockets that supports receiving ancil‐
1264 lary data with the payload data (gen_udp and gen_sctp), the
1265 TCLASS value is returned in an extended return tuple con‐
1266 tained in an ancillary data list. For stream oriented
1267 sockets (gen_tcp) the only way to get the TCLASS value is if
1268 the platform supports the pktoptions option.
1269 {recvtos, Boolean}:
1271 If set to true activates returning the received TOS value on
1272 platforms that implements the protocol IPPROTO_IP option
1273 IP_RECVTOS for the socket. The value is returned as a
1274 {tos,TOS} tuple regardless of if the platform returns an
1275 IP_TOS or an IP_RECVTOS CMSG value.
1276 For packet oriented sockets that supports receiving ancil‐
1278 lary data with the payload data (gen_udp and gen_sctp), the
1279 TOS value is returned in an extended return tuple contained
1280 in an ancillary data list. For stream oriented sockets
1281 (gen_tcp) the only way to get the TOS value is if the plat‐
1282 form supports the pktoptions option.
1283 {recvttl, Boolean}:
1285 If set to true activates returning the received TTL value on
1286 platforms that implements the protocol IPPROTO_IP option
1287 IP_RECVTTL for the socket. The value is returned as a
1288 {ttl,TTL} tuple regardless of if the platform returns an
1289 IP_TTL or an IP_RECVTTL CMSG value.
1290 For packet oriented sockets that supports receiving ancil‐
1292 lary data with the payload data (gen_udp and gen_sctp), the
1293 TTL value is returned in an extended return tuple contained
1294 in an ancillary data list. For stream oriented sockets
1295 (gen_tcp) the only way to get the TTL value is if the plat‐
1296 form supports the pktoptions option.
1297 {reuseaddr, Boolean}:
1299 Allows or disallows local reuse of address. By default, re‐
1300 use is disallowed.
1301 Note:
1303 On Windows this option will be ignored unless Socket is an UDP
1304 socket. This since the behavior of reuseaddr is very different
1305 on Windows compared to other system.
1306 {send_timeout, Integer}:
1309 Only allowed for connection-oriented sockets.
1310 Specifies a longest time to wait for a send operation to be
1312 accepted by the underlying TCP stack. When the limit is ex‐
1313 ceeded, the send operation returns {error,timeout}. How much
1314 of a packet that got sent is unknown; the socket is there‐
1315 fore to be closed whenever a time-out has occurred (see
1316 send_timeout_close below). Defaults to infinity.
1317 {send_timeout_close, Boolean}:
1319 Only allowed for connection-oriented sockets.
1320 Used together with send_timeout to specify whether the
1322 socket is to be automatically closed when the send operation
1323 returns {error,timeout}. The recommended setting is true,
1324 which automatically closes the socket. Defaults to false be‐
1325 cause of backward compatibility.
1326 {show_econnreset, Boolean} (TCP/IP sockets) :
1328 When this option is set to false, which is default, an RST
1329 received from the TCP peer is treated as a normal close (as
1330 though an FIN was sent). A caller to gen_tcp:recv/2 gets
1331 {error, closed}. In active mode, the controlling process re‐
1332 ceives a {tcp_closed, Socket} message, indicating that the
1333 peer has closed the connection.
1334 Setting this option to true allows you to distinguish be‐
1336 tween a connection that was closed normally, and one that
1337 was aborted (intentionally or unintentionally) by the TCP
1338 peer. A call to gen_tcp:recv/2 returns {error, econnreset}.
1339 In active mode, the controlling process receives a {tcp_er‐
1340 ror, Socket, econnreset} message before the usual
1341 {tcp_closed, Socket}, as is the case for any other socket
1342 error. Calls to gen_tcp:send/2 also returns {error, econnre‐
1343 set} when it is detected that a TCP peer has sent an RST.
1344 A connected socket returned from gen_tcp:accept/1 inherits
1346 the show_econnreset setting from the listening socket.
1347 {sndbuf, Size}:
1349 The minimum size of the send buffer to use for the socket.
1350 You are encouraged to use getopts/2, to retrieve the size
1351 set by your operating system.
1352 {priority, Integer}:
1354 Sets the SO_PRIORITY socket level option on platforms where
1355 this is implemented. The behavior and allowed range varies
1356 between different systems. The option is ignored on plat‐
1357 forms where it is not implemented. Use with caution.
1358 {tos, Integer}:
1360 Sets IP_TOS IP level options on platforms where this is im‐
1361 plemented. The behavior and allowed range varies between
1362 different systems. The option is ignored on platforms where
1363 it is not implemented. Use with caution.
1364 {tclass, Integer}:
1366 Sets IPV6_TCLASS IP level options on platforms where this is
1367 implemented. The behavior and allowed range varies between
1368 different systems. The option is ignored on platforms where
1369 it is not implemented. Use with caution.
1370 In addition to these options, raw option specifications can be
1372 used. The raw options are specified as a tuple of arity four,
1373 beginning with tag raw, followed by the protocol level, the op‐
1374 tion number, and the option value specified as a binary. This
1375 corresponds to the second, third, and fourth arguments to the
1376 setsockopt call in the C socket API. The option value must be
1377 coded in the native endianness of the platform and, if a struc‐
1378 ture is required, must follow the structure alignment conven‐
1379 tions on the specific platform.
1380 Using raw socket options requires detailed knowledge about the
1382 current operating system and TCP stack.
1383 Example:
1385 This example concerns the use of raw options. Consider a Linux
1387 system where you want to set option TCP_LINGER2 on protocol
1388 level IPPROTO_TCP in the stack. You know that on this particular
1389 system it defaults to 60 (seconds), but you want to lower it to
1390 30 for a particular socket. Option TCP_LINGER2 is not explicitly
1391 supported by inet, but you know that the protocol level trans‐
1392 lates to number 6, the option number to number 8, and the value
1393 is to be specified as a 32-bit integer. You can use this code
1394 line to set the option for the socket named Sock:
1395 inet:setopts(Sock,[{raw,6,8,<<30:32/native>>}]),
1397 As many options are silently discarded by the stack if they are
1399 specified out of range; it can be a good idea to check that a
1400 raw option is accepted. The following code places the value in
1401 variable TcpLinger2:
1402 {ok,[{raw,6,8,<<TcpLinger2:32/native>>}]}=inet:getopts(Sock,[{raw,6,8,4}]),
1404 Code such as these examples is inherently non-portable, even
1406 different versions of the same OS on the same platform can re‐
1407 spond differently to this kind of option manipulation. Use with
1408 care.
1409 Notice that the default options for TCP/IP sockets can be
1411 changed with the Kernel configuration parameters mentioned in
1412 the beginning of this manual page.
1413 sockname(Socket :: socket()) ->
1415 {ok,
1416 {ip_address(), port_number()} |
1417 returned_non_ip_address()} |
1418 {error, posix()}
1419 Returns the local address and port number for a socket.
1421 Notice that for SCTP sockets this function returns only one of
1423 the socket addresses. Function socknames/1,2 returns all.
1424 socknames(Socket :: socket()) ->
1426 {ok,
1427 [{ip_address(), port_number()} |
1428 returned_non_ip_address()]} |
1429 {error, posix()}
1430 Equivalent to socknames(Socket, 0).
1432 socknames(Socket, Assoc) ->
1434 {ok, [{Address, Port}]} | {error, posix()}
1435 Types:
1437 Socket = socket()
1439 Assoc = #sctp_assoc_change{} | gen_sctp:assoc_id()
1440 Address = ip_address()
1441 Port = integer() >= 0
1442 Returns a list of all local address/port number pairs for a
1444 socket for the specified association Assoc.
1445 This function can return multiple addresses for multihomed sock‐
1447 ets, such as SCTP sockets. For other sockets it returns a one-
1448 element list.
1449 Notice that parameter Assoc is by the SCTP Sockets API Exten‐
1451 sions defined to be ignored for one-to-one style sockets. For
1452 one-to-many style sockets, the special value 0 is defined to
1453 mean that the returned addresses must be without any particular
1454 association. How different SCTP implementations interpret this
1455 varies somewhat.
1456
1458 * e2big - Too long argument list
1459 * eacces - Permission denied
1461 * eaddrinuse - Address already in use
1463 * eaddrnotavail - Cannot assign requested address
1465 * eadv - Advertise error
1467 * eafnosupport - Address family not supported by protocol family
1469 * eagain - Resource temporarily unavailable
1471 * ealign - EALIGN
1473 * ealready - Operation already in progress
1475 * ebade - Bad exchange descriptor
1477 * ebadf - Bad file number
1479 * ebadfd - File descriptor in bad state
1481 * ebadmsg - Not a data message
1483 * ebadr - Bad request descriptor
1485 * ebadrpc - Bad RPC structure
1487 * ebadrqc - Bad request code
1489 * ebadslt - Invalid slot
1491 * ebfont - Bad font file format
1493 * ebusy - File busy
1495 * echild - No children
1497 * echrng - Channel number out of range
1499 * ecomm - Communication error on send
1501 * econnaborted - Software caused connection abort
1503 * econnrefused - Connection refused
1505 * econnreset - Connection reset by peer
1507 * edeadlk - Resource deadlock avoided
1509 * edeadlock - Resource deadlock avoided
1511 * edestaddrreq - Destination address required
1513 * edirty - Mounting a dirty fs without force
1515 * edom - Math argument out of range
1517 * edotdot - Cross mount point
1519 * edquot - Disk quota exceeded
1521 * eduppkg - Duplicate package name
1523 * eexist - File already exists
1525 * efault - Bad address in system call argument
1527 * efbig - File too large
1529 * ehostdown - Host is down
1531 * ehostunreach - Host is unreachable
1533 * eidrm - Identifier removed
1535 * einit - Initialization error
1537 * einprogress - Operation now in progress
1539 * eintr - Interrupted system call
1541 * einval - Invalid argument
1543 * eio - I/O error
1545 * eisconn - Socket is already connected
1547 * eisdir - Illegal operation on a directory
1549 * eisnam - Is a named file
1551 * el2hlt - Level 2 halted
1553 * el2nsync - Level 2 not synchronized
1555 * el3hlt - Level 3 halted
1557 * el3rst - Level 3 reset
1559 * elbin - ELBIN
1561 * elibacc - Cannot access a needed shared library
1563 * elibbad - Accessing a corrupted shared library
1565 * elibexec - Cannot exec a shared library directly
1567 * elibmax - Attempting to link in more shared libraries than system
1569 limit
1570 * elibscn - .lib section in a.out corrupted
1572 * elnrng - Link number out of range
1574 * eloop - Too many levels of symbolic links
1576 * emfile - Too many open files
1578 * emlink - Too many links
1580 * emsgsize - Message too long
1582 * emultihop - Multihop attempted
1584 * enametoolong - Filename too long
1586 * enavail - Unavailable
1588 * enet - ENET
1590 * enetdown - Network is down
1592 * enetreset - Network dropped connection on reset
1594 * enetunreach - Network is unreachable
1596 * enfile - File table overflow
1598 * enoano - Anode table overflow
1600 * enobufs - No buffer space available
1602 * enocsi - No CSI structure available
1604 * enodata - No data available
1606 * enodev - No such device
1608 * enoent - No such file or directory
1610 * enoexec - Exec format error
1612 * enolck - No locks available
1614 * enolink - Link has been severed
1616 * enomem - Not enough memory
1618 * enomsg - No message of desired type
1620 * enonet - Machine is not on the network
1622 * enopkg - Package not installed
1624 * enoprotoopt - Bad protocol option
1626 * enospc - No space left on device
1628 * enosr - Out of stream resources or not a stream device
1630 * enosym - Unresolved symbol name
1632 * enosys - Function not implemented
1634 * enotblk - Block device required
1636 * enotconn - Socket is not connected
1638 * enotdir - Not a directory
1640 * enotempty - Directory not empty
1642 * enotnam - Not a named file
1644 * enotsock - Socket operation on non-socket
1646 * enotsup - Operation not supported
1648 * enotty - Inappropriate device for ioctl
1650 * enotuniq - Name not unique on network
1652 * enxio - No such device or address
1654 * eopnotsupp - Operation not supported on socket
1656 * eperm - Not owner
1658 * epfnosupport - Protocol family not supported
1660 * epipe - Broken pipe
1662 * eproclim - Too many processes
1664 * eprocunavail - Bad procedure for program
1666 * eprogmismatch - Wrong program version
1668 * eprogunavail - RPC program unavailable
1670 * eproto - Protocol error
1672 * eprotonosupport - Protocol not supported
1674 * eprototype - Wrong protocol type for socket
1676 * erange - Math result unrepresentable
1678 * erefused - EREFUSED
1680 * eremchg - Remote address changed
1682 * eremdev - Remote device
1684 * eremote - Pathname hit remote filesystem
1686 * eremoteio - Remote I/O error
1688 * eremoterelease - EREMOTERELEASE
1690 * erofs - Read-only filesystem
1692 * erpcmismatch - Wrong RPC version
1694 * erremote - Object is remote
1696 * eshutdown - Cannot send after socket shutdown
1698 * esocktnosupport - Socket type not supported
1700 * espipe - Invalid seek
1702 * esrch - No such process
1704 * esrmnt - Srmount error
1706 * estale - Stale remote file handle
1708 * esuccess - Error 0
1710 * etime - Timer expired
1712 * etimedout - Connection timed out
1714 * etoomanyrefs - Too many references
1716 * etxtbsy - Text file or pseudo-device busy
1718 * euclean - Structure needs cleaning
1720 * eunatch - Protocol driver not attached
1722 * eusers - Too many users
1724 * eversion - Version mismatch
1726 * ewouldblock - Operation would block
1728 * exdev - Cross-domain link
1730 * exfull - Message tables full
1732 * nxdomain - Hostname or domain name cannot be found
1734Ericsson AB kernel 8.5.3 inet(3)