SSLwrite(3) OpenSSL SSLwrite(3)

NAME
       SSLwrite - write bytes to a TLS/SSL connection.

SYNOPSIS
        #include 

        int SSLwrite(SSL *ssl, const void *buf, int num);

DESCRIPTION
       SSLwrite() writes nnuumm bytes from the buffer bbuuff into the specified ssssll
       connection.

NNOOTTEESS
       If necessary, SSLwrite() will negotiate a TLS/SSL session, if not
       already explicitly performed by SSLconnect(3) or SSLaccept(3). If the
       peer requests a re-negotiation, it will be performed transparently
       during the SSLwrite() operation. The behaviour of SSLwrite() depends
       on the underlying BIO.

       For the transparent negotiation to succeed, the ssssll must have been
       initialized to client or server mode. This is being done by calling
       SSLsetconnectstate(3) or SSLsetacceptstate() before the first
       call to an SSLread(3) or SSLwrite() function.

       If the underlying BIO is bblloocckkiinngg, SSLwrite() will only return, once
       the write operation has been finished or an error occurred, except when
       a renegotiation take place, in which case a SSLERRORWANTREAD may
       occur.  This behaviour can be controlled with the SSLMODEAUTORETRY
       flag of the SSLCTXsetmode(3) call.

       If the underlying BIO is nnoonn-bblloocckkiinngg, SSLwrite() will also return,
       when the underlying BIO could not satisfy the needs of SSLwrite() to
       continue the operation. In this case a call to SSLgeterror(3) with
       the return value of SSLwrite() will yield SSSSLLEERRRROORRWWAANNTTRREEAADD or
       SSSSLLEERRRROORRWWAANNTTWWRRIITTEE. As at any time a re-negotiation is possible, a
       call to SSLwrite() can also cause read operations! The calling process
       then must repeat the call after taking appropriate action to satisfy
       the needs of SSLwrite(). The action depends on the underlying BIO.
       When using a non-blocking socket, nothing is to be done, but select()
       can be used to check for the required condition. When using a buffering
       BIO, like a BIO pair, data must be written into or retrieved out of the
       BIO before being able to continue.

       SSLwrite() will only return with success, when the complete contents
       of bbuuff of length nnuumm has been written. This default behaviour can be
       changed with the SSLMODEENABLEPARTIALWRITE option of
       SSLCTXsetmode(3). When this flag is set, SSLwrite() will also
       return with success, when a partial write has been successfully
       completed. In this case the SSLwrite() operation is considered
       completed. The bytes are sent and a new SSLwrite() operation with a
       new buffer (with the already sent bytes removed) must be started.  A
       partial write is performed with the size of a message block, which is
       16kB for SSLv3/TLSv1.

WWAARRNNIINNGG
       When an SSLwrite() operation has to be repeated because of
       SSSSLLEERRRROORRWWAANNTTRREEAADD or SSSSLLEERRRROORRWWAANNTTWWRRIITTEE, it must be repeated with
       the same arguments.

       When calling SSLwrite() with num=0 bytes to be sent the behaviour is
       undefined.

RETURN VALUES
       The following return values can occur:

       >0  The write operation was successful, the return value is the number
           of bytes actually written to the TLS/SSL connection.

       0   The write operation was not successful. Probably the underlying
           connection was closed. Call SSLgeterror() with the return value
           rreett to find out, whether an error occurred or the connection was
           shut down cleanly (SSLERRORZERORETURN).

           SSLv2 (deprecated) does not support a shutdown alert protocol, so
           it can only be detected, whether the underlying connection was
           closed. It cannot be checked, why the closure happened.

       <0  The write operation was not successful, because either an error
           occurred or action must be taken by the calling process. Call
           SSLgeterror() with the return value rreett to find out the reason.

SEE ALSO
       SSLgeterror(3), SSLread(3), SSLCTXsetmode(3), SSLCTXnew(3),
       SSLconnect(3), SSLaccept(3) SSLsetconnectstate(3), ssl(3), bio(3)



0.9.7l                            2002-07-19                      SSLwrite(3)