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101 lines
3.2 KiB
101 lines
3.2 KiB
=pod |
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=head1 NAME |
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SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL engine mode |
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=head1 SYNOPSIS |
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#include <openssl/ssl.h> |
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long SSL_CTX_set_mode(SSL_CTX *ctx, long mode); |
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long SSL_set_mode(SSL *ssl, long mode); |
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long SSL_CTX_get_mode(SSL_CTX *ctx); |
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long SSL_get_mode(SSL *ssl); |
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=head1 DESCRIPTION |
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SSL_CTX_set_mode() adds the mode set via bitmask in B<mode> to B<ctx>. |
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Options already set before are not cleared. |
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SSL_set_mode() adds the mode set via bitmask in B<mode> to B<ssl>. |
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Options already set before are not cleared. |
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SSL_CTX_get_mode() returns the mode set for B<ctx>. |
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SSL_get_mode() returns the mode set for B<ssl>. |
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=head1 NOTES |
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The following mode changes are available: |
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=over 4 |
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=item SSL_MODE_ENABLE_PARTIAL_WRITE |
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Allow SSL_write(..., n) to return r with 0 < r < n (i.e. report success |
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when just a single record has been written). When not set (the default), |
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SSL_write() will only report success once the complete chunk was written. |
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Once SSL_write() returns with r, r bytes have been successfully written |
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and the next call to SSL_write() must only send the n-r bytes left, |
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imitating the behaviour of write(). |
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=item SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER |
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Make it possible to retry SSL_write() with changed buffer location |
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(the buffer contents must stay the same). This is not the default to avoid |
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the misconception that non-blocking SSL_write() behaves like |
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non-blocking write(). |
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=item SSL_MODE_AUTO_RETRY |
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Never bother the application with retries if the transport is blocking. |
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If a renegotiation take place during normal operation, a |
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L<SSL_read(3)|SSL_read(3)> or L<SSL_write(3)|SSL_write(3)> would return |
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with -1 and indicate the need to retry with SSL_ERROR_WANT_READ. |
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In a non-blocking environment applications must be prepared to handle |
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incomplete read/write operations. |
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In a blocking environment, applications are not always prepared to |
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deal with read/write operations returning without success report. The |
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flag SSL_MODE_AUTO_RETRY will cause read/write operations to only |
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return after the handshake and successful completion. |
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=item SSL_MODE_RELEASE_BUFFERS |
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When we no longer need a read buffer or a write buffer for a given SSL, |
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then release the memory we were using to hold it. Released memory is |
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either appended to a list of unused RAM chunks on the SSL_CTX, or simply |
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freed if the list of unused chunks would become longer than |
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SSL_CTX->freelist_max_len, which defaults to 32. Using this flag can |
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save around 34k per idle SSL connection. |
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This flag has no effect on SSL v2 connections, or on DTLS connections. |
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=item SSL_MODE_SEND_FALLBACK_SCSV |
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Send TLS_FALLBACK_SCSV in the ClientHello. |
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To be set only by applications that reconnect with a downgraded protocol |
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version; see draft-ietf-tls-downgrade-scsv-00 for details. |
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DO NOT ENABLE THIS if your application attempts a normal handshake. |
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Only use this in explicit fallback retries, following the guidance |
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in draft-ietf-tls-downgrade-scsv-00. |
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=back |
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=head1 RETURN VALUES |
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SSL_CTX_set_mode() and SSL_set_mode() return the new mode bitmask |
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after adding B<mode>. |
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SSL_CTX_get_mode() and SSL_get_mode() return the current bitmask. |
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=head1 SEE ALSO |
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L<ssl(3)|ssl(3)>, L<SSL_read(3)|SSL_read(3)>, L<SSL_write(3)|SSL_write(3)> |
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=head1 HISTORY |
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SSL_MODE_AUTO_RETRY as been added in OpenSSL 0.9.6. |
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=cut
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