I’m using SSL for reading data from various remote services over secure websockets. The scheme is following: I create the socket, embed it in the SSL context and add the socket to the reading list for Unix.select. When the socket fires, I use Ssl.read to get the data.
Everything is working well except with the one service where I get Ssl.Read_error.Error_syscall: error:00000000:lib(0):func(0):reason(0) after receiving each websocket frame (size ~5-6Kb). By the way, frames here are much bigger than on other services, but I’m not sure it’s the reason.
I ignore syscall errors, and most probably loose some data, because frames continue to arrive. Then, always after one minute I get Ssl.Read_error.Error_zero_return: error:00000000:lib(0):func(0):reason(0), which means the peer closed SSL socket for writing and I have to restart the process because no new data will be received from this socket.
Problem is perfectly reproducible. At the same time examples for this service and my own test implementation with Node.JS receive the data for hours without any problems.
I assume I do something wrong or setup socket/SSL too straightforward (see below).
Any help or ideas would be strongly appreciated.
let sock = Unix.socket PF_INET SOCK_STREAM 0 in
let laddr = Unix.inet_addr_of_string p.interface in
Unix.bind sock (ADDR_INET (laddr,0));
Unix.connect sock addr;
let (sock, res) =
let req = Bytes.of_string http_request in
if ssl then begin
let ctx = create_context TLSv1_2 Client_context in
let sock = Ssl.embed_socket sock ctx in
(SslSock sock, (write sock req 0 http_request_len))
(UnixSock sock, (Unix.write sock req 0 http_request_len))