Provided by: erlang-manpages_22.2.7+dfsg-1ubuntu0.2_all 
NAME
socket - Socket interface.
DESCRIPTION
This module provides an API for network socket. Functions are provided to create, delete and manupilate
the sockets aswell as sending and reciving data on them.
The intent is that it shall be as "close as possible" to the OS level socket interface. The only
significant addition is that some of the functions, e.g. recv/3, has a timeout argument.
Note:
Some functions allow for an asynchronous call. This is achieved by setting the Timeout argument to
nowait. For instance, if calling the recv/3 function with Timeout set to nowait (recv(Sock, 0, nowait))
when there is actually nothing to read, it will return with {select, SelectInfo} (SelectInfo contains
the SelectRef). When data eventually arrives a 'select' message will be sent to the caller:
: {'$socket', socket(), select, SelectRef}
The caller can now make another call to the recv function and now expect data.
Note that all other users are locked out until the 'current user' has called the function (recv in this
case).
Another message the user must be prepared for (when making asynchronous calls) is the abort message:
: {'$socket', socket(), abort, Info}
This message indicates that the (asynchronous) operation has been aborted. If, for instance, the socket
has been closed (by another process), Info will be {SelectRef, closed}.
Note:
There is currently no support for Windows.
Support for IPv6 has been implemented but not tested.
SCTP has only been partly implemented (and not tested).
DATA TYPES
domain() = local | inet | inet6
type() = stream | dgram | raw | rdm | seqpacket
protocol() =
ip | tcp | udp | sctp | icmp | igmp | {raw, integer()}
socket()
As returned by open/2,3,4 and accept/1,2.
select_tag()
A tag that describes the (select) operation.
select_ref()
A reference that uniquely identifies the (select) operation.
select_info() = {select_info, select_tag(), select_ref()}
socket_counters() = [{socket_counter(), integer() >= 0}]
socket_counter() =
read_byte | read_fails | read_pkg | read_tries | read_waits |
write_byte | write_fails | write_pkg | write_tries |
write_waits
socket_info() =
#{counters := socket_counters(),
num_readers := integer() >= 0,
num_writers := integer() >= 0,
num_acceptors := integer() >= 0}
ip4_address() = {0..255, 0..255, 0..255, 0..255}
ip6_address() =
{0..65535,
0..65535,
0..65535,
0..65535,
0..65535,
0..65535,
0..65535,
0..65535}
ip_address() = ip4_address() | ip6_address()
sockaddr() =
sockaddr_in4() |
sockaddr_in6() |
sockaddr_un() |
sockaddr_ll()
sockaddr_in4() =
#{family := inet,
port := port_number(),
addr := any | broadcast | loopback | ip4_address()}
sockaddr_in6() =
#{family := inet6,
port := port_number(),
addr := any | loopback | ip6_address(),
flowinfo := in6_flow_info(),
scope_id := in6_scope_id()}
sockaddr_un() = #{family := local, path := binary() | string()}
sockaddr_ll() =
#{family := packet,
protocol := integer() >= 0,
ifindex := integer(),
pkttype := packet_type(),
hatype := integer() >= 0,
addr := binary()}
packet_type() =
host | broadcast | multicast | otherhost | outgoing |
loopback | user | kernel | fastroute |
integer() >= 0
port_number() = 0..65535
in6_flow_info() = uint20()
in6_scope_id() = uint32()
send_flags() = [send_flag()]
send_flag() = confirm | dontroute | eor | more | nosignal | oob
recv_flags() = [recv_flag()]
recv_flag() = cmsg_cloexec | errqueue | oob | peek | trunc
shutdown_how() = read | write | read_write
sockopt_level() =
otp | socket | ip | ipv6 | tcp | udp | sctp |
integer() >= 0
otp_socket_option() =
debug | iow | controlling_process | rcvbuf | rcvctrlbuf |
sndctrlbuf | fd
socket_option() =
acceptconn | acceptfilter | bindtodevice | broadcast |
busy_poll | debug | domain | dontroute | error | keepalive |
linger | mark | oobinline | passcred | peek_off | peercred |
priority | protocol | rcvbuf | rcvbufforce | rcvlowat |
rcvtimeo | reuseaddr | reuseport | rxq_ovfl | setfib |
sndbuf | sndbufforce | sndlowat | sndtimeo | timestamp | type
ip_socket_option() =
add_membership | add_source_membership | block_source |
dontfrag | drop_membership | drop_source_membership |
freebind | hdrincl | minttl | msfilter | mtu | mtu_discover |
multicast_all | multicast_if | multicast_loop |
multicast_ttl | nodefrag | options | pktinfo | recverr |
recvif | recvdstaddr | recvopts | recvorigdstaddr | recvtos |
recvttl | retopts | router_alert | sndsrcaddr | tos |
transparent | ttl | unblock_source
ipv6_socket_option() =
addrform | add_membership | authhdr | auth_level | checksum |
drop_membership | dstopts | esp_trans_level |
esp_network_level | faith | flowinfo | hopopts |
ipcomp_level | join_group | leave_group | mtu | mtu_discover |
multicast_hops | multicast_if | multicast_loop | portrange |
pktoptions | recverr | recvhoplimit | hoplimit | recvpktinfo |
pktinfo | recvtclass | router_alert | rthdr | tclass |
unicast_hops | use_min_mtu | v6only
tcp_socket_option() =
congestion | cork | info | keepcnt | keepidle | keepintvl |
maxseg | md5sig | nodelay | noopt | nopush | syncnt |
user_timeout
udp_socket_option() = cork
sctp_socket_option() =
adaption_layer | associnfo | auth_active_key | auth_asconf |
auth_chunk | auth_key | auth_delete_key | autoclose |
context | default_send_params | delayed_ack_time |
disable_fragments | hmac_ident | events | explicit_eor |
fragment_interleave | get_peer_addr_info | initmsg |
i_want_mapped_v4_addr | local_auth_chunks | maxseg |
maxburst | nodelay | partial_delivery_point |
peer_addr_params | peer_auth_chunks | primary_addr |
reset_streams | rtoinfo | set_peer_primary_addr | status |
use_ext_recvinfo
timeval() = #{sec := integer(), usec := integer()}
ip_tos() =
lowdelay | throughput | reliability | mincost | integer()
ip_mreq() =
#{multiaddr := ip4_address(),
interface := any | ip4_address()}
ip_mreq_source() =
#{multiaddr := ip4_address(),
interface := ip4_address(),
sourceaddr := ip4_address()}
ip_pmtudisc() = want | dont | do | probe
ip_msfilter_mode() = include | exclude
ip_msfilter() =
#{multiaddr := ip4_address(),
interface := ip4_address(),
mode := ip_msfilter_mode(),
slist := [ip4_address()]}
ip_pktinfo() =
#{ifindex := integer() >= 0,
spec_dst := ip4_address(),
addr := ip4_address()}
ipv6_mreq() =
#{multiaddr := ip6_address(), interface := integer() >= 0}
ipv6_pmtudisc() = ip_pmtudisc()
ipv6_pktinfo() = #{addr := ip6_address(), ifindex := integer()}
sctp_assoc_id() = int32()
sctp_sndrcvinfo() =
#{stream := uint16(),
ssn := uint16(),
flags := uint16(),
ppid := uint16(),
context := uint16(),
timetolive := uint16(),
tsn := uint16(),
cumtsn := uint16(),
assoc_id := sctp_assoc_id()}
sctp_event_subscribe() =
#{data_in := boolean(),
association := boolean(),
address := boolean(),
send_failure := boolean(),
peer_error := boolean(),
shutdown := boolean(),
partial_delivery := boolean(),
adaptation_layer := boolean(),
authentication := boolean(),
sender_dry := boolean()}
sctp_assocparams() =
#{assoc_id := sctp_assoc_id(),
max_rxt := uint16(),
num_peer_dests := uint16(),
peer_rwnd := uint32(),
local_rwnd := uint32(),
cookie_life := uint32()}
sctp_initmsg() =
#{num_outstreams := uint16(),
max_instreams := uint16(),
max_attempts := uint16(),
max_init_timeo := uint16()}
sctp_rtoinfo() =
#{assoc_id := sctp_assoc_id(),
initial := uint32(),
max := uint32(),
min := uint32()}
msghdr_flag() = ctrunc | eor | errqueue | oob | trunc
msghdr_flags() = [msghdr_flag()]
msghdr() =
#{addr := sockaddr(),
iov := [binary()],
ctrl := [cmsghdr_recv()] | [cmsghdr_send()],
flags := msghdr_flags()}
cmsghdr_level() = socket | ip | ipv6 | integer()
cmsghdr_type() =
credentials | hoplevel | origdstaddr | pktinfo | recvtos |
rights | timestamp | tos | ttl |
integer()
cmsghdr_recv() =
#{level := socket, type := timestamp, data := timeval()} |
#{level := socket, type := rights, data := binary()} |
#{level := socket, type := credentials, data := binary()} |
#{level := socket, type := integer(), data := binary()} |
#{level := ip, type := tos, data := ip_tos()} |
#{level := ip, type := recvtos, data := ip_tos()} |
#{level := ip, type := ttl, data := integer()} |
#{level := ip, type := recvttl, data := integer()} |
#{level := ip, type := pktinfo, data := ip_pktinfo()} |
#{level := ip, type := origdstaddr, data := sockaddr_in4()} |
#{level := ip,
type := recverr,
data := extended_err() | binary()} |
#{level := ip, type := integer(), data := binary()} |
#{level := ipv6, type := hoplevel, data := integer()} |
#{level := ipv6, type := pktinfo, data := ipv6_pktinfo()} |
#{level := ipv6,
type := recverr,
data := extended_err() | binary()} |
#{level := ipv6, type := tclass, data := integer()} |
#{level := ipv6, type := integer(), data := binary()} |
#{level := integer(), type := integer(), data := binary()}
cmsghdr_send() =
#{level := socket, type := timestamp, data := binary()} |
#{level := socket, type := rights, data := binary()} |
#{level := socket, type := credentials, data := binary()} |
#{level := socket, type := integer(), data := binary()} |
#{level := ip, type := tos, data := ip_tos() | binary()} |
#{level := ip, type := ttl, data := integer() | binary()} |
#{level := ip, type := integer(), data := binary()} |
#{level := ipv6, type := tclass, data := integer()} |
#{level := ipv6, type := integer(), data := binary()} |
#{level := udp, type := integer(), data := binary()} |
#{level := integer(), type := integer(), data := binary()}
icmp_dest_unreach() =
net_unreach | host_unreach | port_unreach | frag_needed |
net_unknown | host_unknown |
uint8()
icmpv6_dest_unreach() =
noroute | adm_prohibited | not_neighbour | addr_unreach |
port_unreach | policy_fail | reject_route |
uint8()
ee_origin() = none | local | icmp | icmp6 | uint8()
extended_err() =
#{error := term(),
origin := icmp,
type := dest_unreach,
code := icmp_dest_unreach(),
info := uint32(),
data := uint32(),
offender := undefined | sockaddr()} |
#{error := term(),
origin := icmp,
type := time_exceeded | uint8(),
code := uint8(),
info := uint32(),
data := uint32(),
offender := undefined | sockaddr()} |
#{error := term(),
origin := icmp6,
type := dest_unreach,
code := icmpv6_dest_unreach(),
info := uint32(),
data := uint32(),
offender := undefined | sockaddr()} |
#{error := term(),
origin := icmp6,
type := pkt_toobig | time_exceeded | uint8(),
code := uint8(),
info := uint32(),
data := uint32(),
offender := undefined | sockaddr()} |
#{error := term(),
origin := ee_origin(),
type := uint8(),
code := uint8(),
info := uint32(),
data := uint32(),
offender := undefined | sockaddr()}
uint8() = 0..255
uint16() = 0..65535
uint20() = 0..1048575
uint32() = 0..4294967295
int32() = -2147483648..2147483647
supports_options_socket() = [{socket_option(), boolean()}]
supports_options_ip() = [{ip_socket_option(), boolean()}]
supports_options_ipv6() = [{ipv6_socket_option(), boolean()}]
supports_options_tcp() = [{tcp_socket_option(), boolean()}]
supports_options_udp() = [{udp_socket_option(), boolean()}]
supports_options_sctp() = [{sctp_socket_option(), boolean()}]
supports_options() =
[{socket, supports_options_socket()} |
{ip, supports_options_ip()} |
{ipv6, supports_options_ipv6()} |
{tcp, supports_options_tcp()} |
{udp, supports_options_udp()} |
{sctp, supports_options_sctp()}]
supports_send_flags() = [{send_flag(), boolean()}]
supports_recv_flags() = [{recv_flag(), boolean()}]
EXPORTS
accept(LSocket) -> {ok, Socket} | {error, Reason}
accept(LSocket, Timeout) -> {ok, Socket} | {error, Reason}
Types:
LSocket = socket()
Timeout = timeout()
Socket = socket()
Reason = term()
Accept a connection on a socket.
This call is used with connection-based socket types (stream or seqpacket). It extracs the first
pending connection request for the listen socket and returns the (newly) connected socket.
accept(LSocket, Timeout :: nowait) ->
{ok, Socket} | {select, SelectInfo} | {error, Reason}
Types:
LSocket = Socket = socket()
SelectInfo = select_info()
Reason = term()
Accept a connection on a socket.
This call is used with connection-based socket types (stream or seqpacket). It extracs the first
pending connection request for the listen socket and returns the (newly) connected socket.
In the case when there is no connections waiting, the function will return with the SelectInfo.
The caller can then await a select message, {'$socket', Socket, select, Info} (where Info is the
ref field from the SelectInfo), when a client connects (a subsequent call to accept will then
return the socket).
bind(Socket, Addr) -> {ok, Port} | {error, Reason}
Types:
Socket = socket()
Addr = any | broadcast | loopback | sockaddr()
Port = port_number()
Reason = term()
Bind a name to a socket.
When a socket is created (with open), it has no address assigned to it. bind assigns the address
specified by the Addr argument.
The rules used for name binding vary between domains.
cancel(Socket, SelectInfo) -> ok | {error, Reason}
Types:
Socket = socket()
SelectInfo = select_info()
Reason = term()
Cancel an asynchronous request.
Call this function in order to cancel a previous asynchronous call to, e.g. recv/3.
close(Socket) -> ok | {error, Reason}
Types:
Socket = socket()
Reason = term()
Closes the socket.
Note:
Note that for e.g. protocol = tcp, most implementations doing a close does not guarantee that any
data sent is delivered to the recipient before the close is detected at the remote side.
One way to handle this is to use the shutdown function (socket:shutdown(Socket, write)) to signal
that no more data is to be sent and then wait for the read side of the socket to be closed.
connect(Socket, SockAddr) -> ok | {error, Reason}
connect(Socket, SockAddr, Timeout) -> ok | {error, Reason}
Types:
Socket = socket()
SockAddr = sockaddr()
Timeout = timeout()
Reason = term()
This function connects the socket to the address specied by the SockAddr argument.
connect(Socket, SockAddr, Timeout :: nowait) ->
ok | {select, SelectInfo} | {error, Reason}
Types:
Socket = socket()
SockAddr = sockaddr()
SelectInfo = select_info()
Reason = term()
This function connects the socket to the address specied by the SockAddr argument.
In the case when its not possible to immediately establish a connection, the function will return
with the SelectInfo. The caller can then await a select message, {'$socket', Socket, select, Info}
(where Info is the ref field from the SelectInfo, a subsequent call to connect will then establish
the connection).
getopt(Socket, Level :: otp, Key :: otp_socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: socket, Key :: socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: ip, Key :: ip_socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: ipv6, Key :: ipv6_socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: tcp, Key :: tcp_socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: udp, Key :: udp_socket_option()) ->
{ok, Value} | {error, Reason}
getopt(Socket, Level :: sctp, Key :: sctp_socket_option()) ->
{ok, Value} | {error, Reason}
Types:
Socket = socket()
Value = Reason = term()
Get an option on a socket.
What properties are valid depend both on Level and on what kind of socket it is (domain, type and
protocol).
See the socket options chapter of the users guide for more info.
Note:
Not all options are valid on all platforms. That is, even if "we" support an option, that does not
mean that the underlying OS does.
getopt(Socket, Level, Key) -> ok | {ok, Value} | {error, Reason}
Types:
Socket = socket()
Level = integer()
Key = {NativeOpt, ValueSize}
NativeOpt = integer()
ValueSize = int | bool | integer() >= 0
Value = Reason = term()
Get an option on a socket.
When specifying Level as an integer, and therefor using "native mode", it is *currently* up to the
caller to know how to interpret the result.
For more info, see getopt above.
info(Socket) -> socket_info()
Types:
Socket = socket()
Get miscellaneous info about the socket.
The function returns a map with each info item as a key-value binding. It reflects the "current"
state of the socket.
Note:
In order to ensure data integrity, mutex'es are taken when needed. So, do not call this function
often.
listen(Socket) -> ok | {error, Reason}
listen(Socket, Backlog) -> ok | {error, Reason}
Types:
Socket = socket()
Backlog = integer() >= 1
Reason = term()
Listen for connections on a socket.
open(Domain, Type) -> {ok, Socket} | {error, Reason}
open(Domain, Type, Protocol) -> {ok, Socket} | {error, Reason}
open(Domain, Type, Protocol, Extra) ->
{ok, Socket} | {error, Reason}
Types:
Domain = domain()
Type = type()
Protocol = default | protocol()
Extra = map()
Socket = socket()
Reason = term()
Creates an endpoint (socket) for communication.
For some types there is a default protocol, indicated by default, which it may be possible to
specify. And for Domain = local, if a protocol is pecified, it must be default.
The Extra argument is intended for "obscure" options. Currently the only supported option is
netns, which is only supported on the linux platform.
Note:
It may not be possible to specify the default protocol (except when Domain = local). We need to be
able to retreive the resulting protocol, which is not possble on all platforms.
peername(Socket) -> {ok, SockAddr} | {error, Reason}
Types:
Socket = socket()
SockAddr = sockaddr()
Reason = term()
Returns the address of the peer connected to the socket.
recv(Socket) -> {ok, Data} | {error, Reason}
recv(Socket, Length) -> {ok, Data} | {error, Reason}
recv(Socket, Length, Flags) -> {ok, Data} | {error, Reason}
recv(Socket, Length, Timeout) -> {ok, Data} | {error, Reason}
recv(Socket, Length, Flags, Timeout) ->
{ok, Data} | {error, Reason}
Types:
Socket = socket()
Length = integer() >= 0
Flags = recv_flags()
Timeout = timeout()
Data = binary()
Reason = term()
Receive a message from a socket.
There is a special case for the argument Length. If it is set to zero (0), it means "give me
everything you currently have".
recv(Socket, Length, Timeout :: nowait) ->
{ok, Data} |
{select, SelectInfo} |
{ok, {Data, SelectInfo}} |
{error, Reason}
recv(Socket, Length, Flags, Timeout :: nowait) ->
{ok, Data} |
{select, SelectInfo} |
{ok, {Data, SelectInfo}} |
{error, Reason}
Types:
Socket = socket()
Length = integer() >= 0
Flags = recv_flags()
Data = binary()
SelectInfo = select_info()
Reason = term()
Receive a message from a socket.
There is a special case for the argument Length. If it is set to zero (0), it means "give me
everything you currently have".
In the case when there is no data waiting, the function will return with the SelectInfo. The
caller can then await a select message, {'$socket', Socket, select, Info} (where Info is the ref
field from the SelectInfo), when data has arrived (a subsequent call to recv will then return the
data).
Note that if a length (> 0) is specified, and only part of that amount of data is available, the
function will return with that data and the SelectInfo (if the caller don't want to wait for the
remaining data, it must immediately call the cancel/2 function.)
recvfrom(Socket) -> {ok, {Source, Data}} | {error, Reason}
recvfrom(Socket, BufSz) -> {ok, {Source, Data}} | {error, Reason}
recvfrom(Socket, Flags, Timeout) ->
{ok, {Source, Data}} | {error, Reason}
recvfrom(Socket, BufSz, Flags) ->
{ok, {Source, Data}} | {error, Reason}
recvfrom(Socket, BufSz, Timeout) ->
{ok, {Source, Data}} | {error, Reason}
recvfrom(Socket, BufSz, Flags, Timeout) ->
{ok, {Source, Data}} | {error, Reason}
Types:
Socket = socket()
BufSz = integer() >= 0
Flags = recv_flags()
Timeout = timeout()
Source = sockaddr() | undefined
Data = binary()
Reason = term()
Receive a message from a socket.
This function reads "messages", which means that regardless of how much we want to read, it
returns when we get a message (if the buffer size is too small, the message will be truncated).
The BufSz argument basically defines the size of the receive buffer. By setting the value to zero
(0), the configured size (setopt with Level = otp and Key = rcvbuf) is used.
It may be impossible to know what (buffer) size is appropriate "in advance", and in those cases it
may be convenient to use the (recv) 'peek' flag. When this flag is provided, the message is *not*
"consumed" from the underlying buffers, so another recvfrom call is needed, possibly with a then
adjusted buffer size.
recvfrom(Socket, Flags, Timeout :: nowait) ->
{ok, {Source, Data}} |
{select, SelectInfo} |
{error, Reason}
recvfrom(Socket, BufSz, Timeout :: nowait) ->
{ok, {Source, Data}} |
{select, SelectInfo} |
{error, Reason}
recvfrom(Socket, BufSz, Flags, Timeout :: nowait) ->
{ok, {Source, Data}} |
{select, SelectInfo} |
{error, Reason}
Types:
Socket = socket()
BufSz = integer() >= 0
Flags = recv_flags()
Source = sockaddr() | undefined
Data = binary()
SelectInfo = select_info()
Reason = term()
Receive a message from a socket.
This function reads "messages", which means that regardless of how much we want to read, it
returns when we get a message (if the buffer size is too small, the message will be truncated).
The BufSz argument basically defines the size of the receive buffer. By setting the value to zero
(0), the configured size (setopt with Level = otp and Key = rcvbuf) is used.
It may be impossible to know what (buffer) size is appropriate "in advance", and in those cases it
may be convenient to use the (recv) 'peek' flag. When this flag is provided, the message is *not*
"consumed" from the underlying buffers, so another recvfrom call is needed, possibly with a then
adjusted buffer size.
In the case when there is no data waiting, the function will return with the SelectInfo. The
caller can then await a select message, {'$socket', Socket, select, Info} (where Info is the ref
field from the SelectInfo), when data has arrived (a subsequent call to recvfrom will then return
the data).
recvmsg(Socket) -> {ok, MsgHdr} | {error, Reason}
recvmsg(Socket, Flags) -> {ok, MsgHdr} | {error, Reason}
recvmsg(Socket, Timeout) -> {ok, MsgHdr} | {error, Reason}
recvmsg(Socket, Flags, Timeout) -> {ok, MsgHdr} | {error, Reason}
recvmsg(Socket, BufSz, CtrlSz) -> {ok, MsgHdr} | {error, Reason}
recvmsg(Socket, BufSz, CtrlSz, Flags, Timeout) ->
{ok, MsgHdr} | {error, Reason}
Types:
Socket = socket()
BufSz = CtrlSz = integer() >= 0
Flags = recv_flags()
Timeout = timeout()
MsgHdr = msghdr()
Reason = term()
Receive a message from a socket.
This function reads "messages", which means that regardless of how much we want to read, it
returns when we get a message.
The message will be delivered in the form of a msghdr(), which may contain the source address (if
socket not connected), a list of cmsghdr_recv() (depends on what socket options have been set and
what the protocol and platform supports) and also a set of flags, providing further info about the
read.
The BufSz argument basically defines the size of the receive buffer. By setting the value to zero
(0), the configured size (setopt with Level = otp and Key = rcvbuf) is used.
The CtrlSz argument basically defines the size of the receive buffer for the control messages. By
setting the value to zero (0), the configured size (setopt with Level = otp) is used.
It may be impossible to know what (buffer) size is appropriate "in advance", and in those cases it
may be convenient to use the (recv) 'peek' flag. When this flag is provided, the message is *not*
"consumed" from the underlying buffers, so another recvmsg call is needed, possibly with a then
adjusted buffer size.
recvmsg(Socket, Timeout :: nowait) ->
{ok, MsgHdr} | {select, SelectInfo} | {error, Reason}
recvmsg(Socket, Flags, Timeout :: nowait) ->
{ok, MsgHdr} | {select, SelectInfo} | {error, Reason}
recvmsg(Socket, BufSz, CtrlSz, Flags, Timeout :: nowait) ->
{ok, MsgHdr} | {select, SelectInfo} | {error, Reason}
Types:
Socket = socket()
BufSz = CtrlSz = integer() >= 0
Flags = recv_flags()
MsgHdr = msghdr()
SelectInfo = select_info()
Reason = term()
Receive a message from a socket.
This function reads "messages", which means that regardless of how much we want to read, it
returns when we get a message.
The message will be delivered in the form of a msghdr(), which may contain the source address (if
socket not connected), a list of cmsghdr_recv() (depends on what socket options have been set and
what the protocol and platform supports) and also a set of flags, providing further info about the
read.
The BufSz argument basically defines the size of the receive buffer. By setting the value to zero
(0), the configured size (setopt with Level = otp and Key = rcvbuf) is used.
The CtrlSz argument basically defines the size of the receive buffer for the control messages. By
setting the value to zero (0), the configured size (setopt with Level = otp) is used.
It may be impossible to know what (buffer) size is appropriate "in advance", and in those cases it
may be convenient to use the (recv) 'peek' flag. When this flag is provided, the message is *not*
"consumed" from the underlying buffers, so another recvmsg call is needed, possibly with a then
adjusted buffer size.
In the case when there is no data waiting, the function will return with the SelectInfo. The
caller can then await a select message, {'$socket', Socket, select, Info} (where Info is the ref
field from the SelectInfo), when data has arrived (a subsequent call to recvmsg will then return
the data).
send(Socket, Data) -> ok | {error, Reason}
send(Socket, Data, Flags) -> ok | {error, Reason}
send(Socket, Data, Timeout) -> ok | {error, Reason}
send(Socket, Data, Flags, Timeout) -> ok | {error, Reason}
Types:
Socket = socket()
Data = iodata()
Flags = send_flags()
Timeout = timeout()
Reason = term()
Send a message on a connected socket.
send(Socket, Data, Timeout :: nowait) ->
ok |
{select, SelectInfo} |
{ok, {RestData, SelectInfo}} |
{error, Reason}
send(Socket, Data, Flags, Timeout :: nowait) ->
ok |
{select, SelectInfo} |
{ok, {RestData, SelectInfo}} |
{error, Reason}
Types:
Socket = socket()
Data = iodata()
Flags = send_flags()
RestData = binary()
SelectInfo = select_info()
Reason = term()
Send a message on a connected socket.
In the case when there is no room in the (system-) buffers, the function will return with the
SelectInfo. The caller can then await a select message, {'$socket', Socket, select, Info} (where
Info is the ref field from the SelectInfo), when there is room for more data (a subsequent call to
send will then send the data).
Note that if not all the data was sent, the function will return with the remaining data and the
SelectInfo (if the caller don't want to wait to be able to send the rest, it should immediately
call the cancel/2 function.)
sendmsg(Socket, MsgHdr) -> ok | {error, Reason}
sendmsg(Socket, MsgHdr, Flags) -> ok | {error, Reason}
sendmsg(Socket, MsgHdr, Timeout) -> ok | {error, Reason}
sendmsg(Socket, MsgHdr, Flags, Timeout) ->
ok | {ok, Remaining} | {error, Reason}
Types:
Socket = socket()
MsgHdr = msghdr()
Flags = send_flags()
Timeout = timeout()
Remaining = erlang:iovec()
Reason = term()
Send a message on a socket. The destination, if needed (socket not connected) is provided in the
MsgHdr, which also contains the message to send, The MsgHdr may also contain an list of optional
cmsghdr_send() (depends on what the protocol and platform supports).
Unlike the send function, this one sends one message. This means that if, for whatever reason, its
not possible to send the message in one go, the function will instead return with the remaining
data ({ok, Remaining}). Thereby leaving it up to the caller to decide what to do (retry with the
remaining data of give up).
sendmsg(Socket, MsgHdr, Timeout :: nowait) ->
ok | {select, SelectInfo} | {error, Reason}
sendmsg(Socket, MsgHdr, Flags, Timeout :: nowait) ->
ok |
{ok, Remaining} |
{select, SelectInfo} |
{error, Reason}
Types:
Socket = socket()
MsgHdr = msghdr()
Flags = send_flags()
Remaining = erlang:iovec()
SelectInfo = select_info()
Reason = term()
Send a message on a socket. The destination, if needed (socket not connected) is provided in the
MsgHdr, which also contains the message to send, The MsgHdr may also contain an list of optional
cmsghdr_send() (depends on what the protocol and platform supports).
Unlike the send function, this one sends one message. This means that if, for whatever reason, its
not possible to send the message in one go, the function will instead return with the remaining
data ({ok, Remaining}). Thereby leaving it up to the caller to decide what to do (retry with the
remaining data of give up).
In the case when there is no room in the (system-) buffers, the function will return with the
SelectInfo. The caller can then await a select message, {'$socket', Socket, select, Info} (where
Info is the ref field from the SelectInfo), when there is room for more data (a subsequent call to
sendmsg will then send the data).
sendto(Socket, Data, Dest) -> ok | {error, Reason}
sendto(Socket, Data, Dest, Flags) -> ok | {error, Reason}
sendto(Socket, Data, Dest, Timeout) -> ok | {error, Reason}
sendto(Socket, Data, Dest, Flags, Timeout) -> ok | {error, Reason}
Types:
Socket = socket()
Data = binary()
Dest = sockaddr()
Flags = send_flags()
Timeout = timeout()
Reason = term()
Send a message on a socket, to the specified destination.
sendto(Socket, Data, Dest, Timeout :: nowait) ->
ok | {select, SelectInfo} | {error, Reason}
sendto(Socket, Data, Dest, Flags, Timeout :: nowait) ->
ok | {select, SelectInfo} | {error, Reason}
Types:
Socket = socket()
Data = binary()
Dest = sockaddr()
Flags = send_flags()
SelectInfo = select_info()
Reason = term()
Send a message on a socket, to the specified destination.
In the case when there is no room in the (system-) buffers, the function will return with the
SelectInfo. The caller can then await a select message, {'$socket', Socket, select, Info} (where
Info is the ref field from the SelectInfo), when there is room for more data (a subsequent call to
sendto will then send the data).
setopt(Socket, Level :: otp, Key :: otp_socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: socket, Key :: socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: ip, Key :: ip_socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: ipv6, Key :: ipv6_socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: tcp, Key :: tcp_socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: udp, Key :: udp_socket_option(), Value) ->
ok | {error, Reason}
setopt(Socket, Level :: sctp, Key :: sctp_socket_option(), Value) ->
ok | {error, Reason}
Types:
Socket = socket()
Value = Reason = term()
Set options on a socket.
What properties are valid depend both on Level and on what kind of socket it is (domain, type and
protocol).
See the socket options chapter of the users guide for more info.
Note:
Not all options are valid on all platforms. That is, even if "we" support an option, that does not
mean that the underlying OS does.
Note:
Sockets are set 'non-blocking' when created, so this option is *not* available (as it would
adversely effect the Erlang VM to set a socket 'blocking').
setopt(Socket, Level, Key, Value) -> ok | {error, Reason}
Types:
Socket = socket()
Level = Key = integer() >= 0
Value = binary()
Reason = term()
Set options on a socket.
When specifying Level as an integer, and therefor using "native mode", it is *currently* up to the
caller to know how to encode the Value.
For more info, see setopt above.
shutdown(Socket, How) -> ok | {error, Reason}
Types:
Socket = socket()
How = shutdown_how()
Reason = term()
Shut down all or part of a full-duplex connection.
sockname(Socket) -> {ok, SockAddr} | {error, Reason}
Types:
Socket = socket()
SockAddr = sockaddr()
Reason = term()
Returns the current address to which the socket is bound.
supports() ->
[{options, supports_options()} |
{sctp, boolean()} |
{ipv6, boolean()} |
{local, boolean()} |
{send_flags, supports_send_flags()} |
{recv_flags, supports_recv_flags()}]
supports(Key1 :: options) -> supports_options()
supports(Key1 :: sctp) -> boolean()
supports(Key1 :: ipv6) -> boolean()
supports(Key1 :: local) -> boolean()
supports(Key1 :: send_flags) -> supports_send_flags()
supports(Key1 :: recv_flags) -> supports_recv_flags()
supports(Key1) -> false
supports(Key1 :: options, Level :: socket) ->
supports_options_socket()
supports(Key1 :: options, Level :: ip) -> supports_options_ip()
supports(Key1 :: options, Level :: ipv6) ->
supports_options_ipv6()
supports(Key1 :: options, Level :: tcp) -> supports_options_tcp()
supports(Key1 :: options, Level :: udp) -> supports_options_udp()
supports(Key1 :: options, Level :: sctp) ->
supports_options_sctp()
supports(Key1 :: send_flags, SendFlag :: send_flag()) -> boolean()
supports(Key1 :: recv_flags, RecvFlag :: recv_flag()) -> boolean()
supports(Key1, Key2) -> false
supports(Key1 :: options, Level :: socket, Opt :: socket_option()) ->
boolean()
supports(Key1 :: options, Level :: ip, Opt :: ip_socket_option()) ->
boolean()
supports(Key1 :: options,
Level :: ipv6,
Opt :: ipv6_socket_option()) ->
boolean()
supports(Key1 :: options,
Level :: tcp,
Opt :: tcp_socket_option()) ->
boolean()
supports(Key1 :: options,
Level :: udp,
Opt :: udp_socket_option()) ->
boolean()
supports(Key1 :: options,
Level :: sctp,
Opt :: sctp_socket_option()) ->
boolean()
supports(Key1, Key2, Key3) -> false
Types:
Key1 = Key2 = Key3 = term()
This function intends to retreive information about what the platform supports. Such as if SCTP is
supported. Or which socket options are supported.
EXAMPLES
client(Addr, SAddr, SPort) ->
{ok, Sock} = socket:open(inet, stream, tcp),
{ok, _} = socket:bind(Sock, #{family => inet,
addr => Addr}),
ok = socket:connect(Sock, #{family => inet,
addr => SAddr,
port => SPort}),
Msg = list_to_binary("hello"),
ok = socket:send(Sock, Msg),
ok = socket:shutdown(Sock, write),
{ok, Msg} = socket:recv(Sock),
ok = socket:close(Sock).
server(Addr, Port) ->
{ok, LSock} = socket:open(inet, stream, tcp),
{ok, _} = socket:bind(LSock, #{family => inet,
port => Port,
addr => Addr}),
ok = socket:listen(LSock),
{ok, Sock} = socket:accept(LSock),
{ok, Msg} = socket:recv(Sock),
ok = socket:send(Sock, Msg),
ok = socket:shutdown(Sock, write),
ok = socket:close(Sock),
ok = socket:close(LSock).