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Additional explanations for SSL_ERROR_WANT_READ/WRITE.

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Bodo Möller 2000-11-12 19:17:22 +00:00
parent 3d6001f7b9
commit 2984b0ae24
1 changed files with 18 additions and 8 deletions
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doc/ssl/SSL_get_error.pod
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@ -48,16 +48,26 @@ has been closed.
=item SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
The operation did not complete; the same TLS/SSL I/O function should be
called again later. There will be protocol progress if, by then, the
underlying B<BIO> has data available for reading (if the result code is
B<SSL_ERROR_WANT_READ>) or allows writing data (B<SSL_ERROR_WANT_WRITE>).
For socket B<BIO>s (e.g. when SSL_set_fd() was used) this means that
select() or poll() on the underlying socket can be used to find out
when the TLS/SSL I/O function should be retried.
called again later. If, by then, the underlying B<BIO> has data
available for reading (if the result code is B<SSL_ERROR_WANT_READ>)
or allows writing data (B<SSL_ERROR_WANT_WRITE>), then some TLS/SSL
protocol progress will take place, i.e. at least part of an TLS/SSL
record will be read or written. Note that the retry may again lead to
a B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE> condition.
There is no fixed upper limit for the number of iterations that
may be necessary until progress becomes visible at application
protocol level.
For socket B<BIO>s (e.g. when SSL_set_fd() was used), select() or
poll() on the underlying socket can be used to find out when the
TLS/SSL I/O function should be retried.
Caveat: Any TLS/SSL I/O function can lead to either of
B<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>, i.e. SSL_read()
may want to write data and SSL_write() may want to read data.
B<SSL_ERROR_WANT_READ> and B<SSL_ERROR_WANT_WRITE>. In particular,
SSL_read() may want to write data and SSL_write() may want to read
data. This is because TLS/SSL handshakes may occur at any time
during the protocol (initiated by either the client or the server);
SSL_read() and SSL_write() will handle any pending handshakes.
=item SSL_ERROR_WANT_X509_LOOKUP