[erlang-questions] Matching IP address in socket module

[Micael Karlberg]

case socket:recvfrom(Sock, 0, nowait) of
       {ok, {#{family := Domain,
               port   := Port,
               addr   := Addr}, Data}} ->
       .
       .
       .


/BMK

On 2019-10-24 14:02, Mark Jones wrote:
>    Thomas
> 
> While I have not used the socket module, the documentation indicates that the Source variable 
> returned from the recvfrom function is a map not a record. So you would just need to use map 
> matching syntax to extract the data you want.
> 
> Mark
> 
> On Thu, Oct 24, 2019 at 6:42 AM Thomas Pircher <thp+erlang@REDACTED <mailto:thp%2Berlang@REDACTED>> wrote:
> 
>     Hi,
> 
>     I'm trying to use the new socket module, and I'm having difficulties
>     extracting the IP address from the socket:sockaddr_in4 record, as
>     returned from socket:recvfrom.
>     In my particular case I'm only dealing with IPv4 addresses for now.
> 
>      > receive_data(Sock, State) ->
>      >     case socket:recvfrom(Sock, 0, nowait) of
>      >         {ok, {From, Data}} ->
>      >             NewState = handle_data(From, Data, State),
>      >             receive_data(Sock, NewState);
>      >         {select, _SelectInfo} -> {ok, State};
>      >         {error, Reason} -> {error, Reason}
>      >     end.
> 
>     The problem is I don't really know how to match the From address. I would like
>     to match the IP address in the above statement, something like the following
>     pseudo-code:
> 
>      >     case socket:recvfrom(Sock, 0, nowait) of
>      >         {ok, {#socket:sockaddr_in4{family=inet, addr=From}, Data}} ->
> 
>     My (limited) understanding is that I would need to include a header file to use
>     records from another module, but as far as I can see, the socket module does
>     not define a header file.
>     If need be I can extract the address in the body of the case statement.
> 
>     How would I get the sender address from the return value of the recvfrom function?
> 
>     Thanks,
>     Thomas
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