Erlang Run-Time System Application (ERTS)

User's Guide

Version 10.4

Chapters

12 Socket Usage

12.1  Introduction

The socket interface (module) is basically an "thin" layer on top of the OS socket interface. It is assumed that, unless you have special needs, gen_[tcp|udp|sctp] should be sufficent.

Note that just because we have a documented and described option, it does not mean that the OS supports it. So its recommended that the user reads the platform specific documentation for the option used.

12.2  Socket Options

Options for level otp:

Option Name Value Type Set Get Other Requirements and comments
assoc_id integer() no yes type = seqpacket, protocol = sctp, is an association
debug boolean() yes yes none
iow boolean() yes yes none
controlling_process pid() yes yes none
rcvbuf default | pos_integer() | {pos_integer(), pos_ineteger()} yes yes 'default' only valid for set. The tuple form is only valid for type 'stream' and protocol 'tcp'.
rcvctrlbuf default | pos_integer() yes yes default only valid for set
sndctrlbuf default | pos_integer() yes yes default only valid for set
fd integer() no yes none

Table 12.1:   option levels

Options for level socket:

Option Name Value Type Set Get Other Requirements and comments
acceptcon boolean() no yes none
bindtodevice string() yes yes none
broadcast boolean() yes yes type = dgram
debug integer() yes yes requires admin capability
domain domain() no yes Not on FreeBSD (for instance)
dontroute boolean() yes yes none
keepalive boolean() yes yes none
linger abort | linger() yes yes none
oobinline boolean() yes yes none
peek_off integer() yes yes domain = local (unix)
priority integer() yes yes none
protocol protocol() no yes none
rcvbuf non_neg_integer() yes yes none
rcvlowat non_neg_integer() yes yes none
rcvtimeo timeval() yes yes none
reuseaddr boolean() yes yes none
reuseport boolean() yes yes domain = inet | inet6
sndbuf non_neg_integer() yes yes none
sndlowat non_neg_integer() yes yes not changeable on Linux
sndtimeo timeval() yes yes none
timestamp boolean() yes yes none
type type() no yes none

Table 12.2:   socket options

Options for level ip:

Option Name Value Type Set Get Other Requirements and comments
add_membership ip_mreq() yes no none
add_source_membership ip_mreq_source() yes no none
block_source ip_mreq_source() yes no none
drop_membership ip_mreq() yes no none
drop_source_membership ip_mreq_source() yes no none
freebind boolean() yes yes none
hdrincl boolean() yes yes type = raw
minttl integer() yes yes type = raw
msfilter null | ip_msfilter() yes no none
mtu integer() no yes type = raw
mtu_discover ip_pmtudisc() yes yes none
multicast_all boolean() yes yes none
multicast_if any | ip4_address() yes yes none
multicast_loop boolean() yes yes none
multicast_ttl uint8() yes yes none
nodefrag boolean() yes yes type = raw
pktinfo boolean() yes yes type = dgram
recvdstaddr boolean() yes yes type = dgram
recverr boolean() yes yes none
recvif boolean() yes yes type = dgram | raw
recvopts boolean() yes yes type =/= stream
recvorigdstaddr boolean() yes yes none
recvttl boolean() yes yes type =/= stream
retopts boolean() yes yes type =/= stream
router_alert integer() yes yes type = raw
sendsrcaddr boolean() yes yes none
tos ip_tos() yes yes some high-priority levels may require superuser capability
transparent boolean() yes yes requires admin capability
ttl integer() yes yes none
unblock_source ip_mreq_source() yes no none

Table 12.3:   ip options

Options for level ipv6:

Option Name Value Type Set Get Other Requirements and comments
addrform inet yes no allowed only for IPv6 sockets that are connected and bound to a v4-mapped-on-v6 address
add_membership ipv6_mreq() yes no none
authhdr boolean() yes yes type = dgram | raw, obsolete?
drop_membership ipv6_mreq() yes no none
dstopts boolean() yes yes type = dgram | raw, requires superuser privileges to update
flowinfo boolean() yes yes type = dgram | raw, requires superuser privileges to update
hoplimit boolean() yes yes type = dgram | raw, requires superuser privileges to update
hopopts boolean() yes yes type = dgram | raw, requires superuser privileges to update
mtu boolean() yes yes Get: Only after the socket has been connected
mtu_discover ipv6_pmtudisc() yes yes none
multicast_hops default | uint8() yes yes none
multicast_if integer() yes yes type = dgram | raw
multicast_loop boolean() yes yes none
recverr boolean() yes yes none
recvpktinfo | pktinfo boolean() yes yes type = dgram | raw
router_alert integer() yes yes type = raw
rthdr boolean() yes yes type = dgram | raw, requires superuser privileges to update
unicast_hops default | uint8() yes yes none
v6only boolean() yes no none

Table 12.4:   ipv6 options

Options for level tcp:

Option Name Value Type Set Get Other Requirements and comments
congestion string() yes yes none
maxseg integer() yes yes none
nodelay boolean() yes yes none

Table 12.5:   tcp options

Options for level udp:

Option Name Value Type Set Get Other Requirements and comments
cork boolean() yes yes none

Table 12.6:   udp options

Options for level sctp:

Option Name Value Type Set Get Other Requirements and comments
associnfo sctp_assocparams() yes yes none
autoclose non_neg_integer() yes yes none
disable_fragments boolean() yes yes none
events sctp_event_subscribe() yes no none
initmsg sctp_initmsg() yes yes none
maxseg non_neg_integer() yes yes none
nodelay boolean() yes yes none
rtoinfo sctp_rtoinfo() yes yes none

Table 12.7:   sctp options