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authorBodo Möller <bodo@openssl.org>2000-11-12 19:17:22 +0000
committerBodo Möller <bodo@openssl.org>2000-11-12 19:17:22 +0000
commit2984b0ae248f876823e8981d3b1bbf9f9bf2e3ff (patch)
tree5f89f0fc9d0a77422bff9506113954b08ed6fdd0 /doc/ssl/SSL_get_error.pod
parent3d6001f7b94187d37987cf95385996363e26ca7c (diff)
downloadopenssl-2984b0ae248f876823e8981d3b1bbf9f9bf2e3ff.tar.gz
Additional explanations for SSL_ERROR_WANT_READ/WRITE.
Diffstat (limited to 'doc/ssl/SSL_get_error.pod')
-rw-r--r--doc/ssl/SSL_get_error.pod26
1 files changed, 18 insertions, 8 deletions
diff --git a/doc/ssl/SSL_get_error.pod b/doc/ssl/SSL_get_error.pod
index d85b564258..747b99741b 100644
--- a/doc/ssl/SSL_get_error.pod
+++ b/doc/ssl/SSL_get_error.pod
@@ -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