gen_udp模块¶

open/1/2

open(Port) -> {ok, Socket} | {error, Reason}
open(Port, Opts) -> {ok, Socket} | {error, Reason}
类型:
Port = inet:port_number()
Opts = [Option]
Option = option()
Socket = socket()
Reason = inet:posix()

说明:

将udp端口和调用进程相关联

可选项option():

{ip, inet:socket_address()} |
    % 多网口的服务器指定ip
{fd, integer() >= 0} |
    % 如果socket不是由gen_udp打开的,可通过此option接收
{ifaddr, inet:socket_address()} |
    % 类似选项{ip, Ip}
inet:address_family() |
    % inet | inet6 | local
{port, inet:port_number()} |
{netns, file:filename_all()} |
{bind_to_device, binary()} |
{active, true | false | once | -32768..32767} |
{add_membership, {inet:ip_address(), inet:ip_address()}} |
{broadcast, boolean()} |
{buffer, integer() >= 0} |
{deliver, port | term} |
{dontroute, boolean()} |
{drop_membership, {inet:ip_address(), inet:ip_address()}} |
{header, integer() >= 0} |
{high_msgq_watermark, integer() >= 1} |
{low_msgq_watermark, integer() >= 1} |
{mode, list | binary} |
list |
  % 以list的形式提供收到的包
binary |
    % 以binary的形式提供收到的包
{multicast_if, inet:ip_address()} |
    % 设置multicast scoket的 local device
{multicast_loop, boolean()} |
    % true: 发送的multicast packets被looped加到local socket.
{multicast_ttl, integer() >= 0} |

{priority, integer() >= 0} |
{raw,
 Protocol :: integer() >= 0,
 OptionNum :: integer() >= 0,
 ValueBin :: binary()} |
{read_packets, integer() >= 0} |
{recbuf, integer() >= 0} |
{reuseaddr, boolean()} |
{sndbuf, integer() >= 0} |
{tos, integer() >= 0} |
{tclass, integer() >= 0} |
{ttl, integer() >= 0} |
{recvtos, boolean()} |
{recvtclass, boolean()} |
{recvttl, boolean()} |
{ipv6_v6only, boolean()}

实例¶

server:

{ok, Socket} = gen_udp:open(Port, [binary, {active, true}]).
receive
    {udp, Socket, Host, Port, Bin} ->
        io:format("Host=~p, Port=~p, 内容:~p~n", [Host,Port,Bin])
end.

client:

{ok, Socket} = gen_udp:open(0, [binary, {active, true}]).
ok = gen_udp:send(Socket, "localhost", 8888, "aaa").