On Wednesday, 31 March 2021 at 04:13:12 UTC+1 matt....@gmail.com wrote:
> for i := 0; i > 5; i++ {
> // handle a single message
> n, err := c.Read(buf)
> if err == io.EOF {
> break
> }
> fmt.Fprintf(c, "Message Count %d, Data %s", i+1, buf[:n])
>
I will point out that it's possible for io.Read to return valid data *and*
an error (including io.EOF). See https://golang.org/pkg/io/#Reader
*"When Read encounters an error or end-of-file condition after successfully
reading n > 0 bytes, it returns the number of bytes read. It may return the
(non-nil) error from the same call or return the error (and n == 0) from a
subsequent call. An instance of this general case is that a Reader
returning a non-zero number of bytes at the end of the input stream may
return either err == EOF or err == nil. The next Read should return 0,
EOF."*
So perhaps you want something more like this:
n, err := c.Read(buf)
if n > 0 {
fmt.Fprintf(c, "Message Count %d, Data %s", i+1, buf[:n])
}
if err == io.EOF {
break
}
if err != nil {
fmt.Fprintf("Error: %s", err)
break
}
Note that TCP is stream-oriented, so the number of bytes returned from Read
> is not at all guaranteed to match the number of bytes the client sent. The
> returned data can be part of one or more messages. You need some other
> mechanism to divide the data received into messages. For example you might
> want to read a line at a time instead.
>
That's critical. Messages need to be delimited somehow. Some protocols
send a length followed by that number of bytes of data. Note that the JSON
encoder/decoder in go supports sending objects one after the other - that
is, the structure of a JSON object performs the delineation. After the
start of an object '{' the decoder will keep consuming data until it gets
the matching close '}'
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