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tls13-early-data.md: Adapt code examples to new coding style

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Signed-off-by: Ronald Cron <ronald.cron@arm.com>
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Ronald Cron 2024-03-13 14:22:19 +01:00
parent b372b2e5bb
commit 0fce958f17
1 changed files with 59 additions and 53 deletions
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112
docs/tls13-early-data.md
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@ -6,29 +6,28 @@ An application function to write and send a buffer of data to a server through
TLS may plausibly look like: TLS may plausibly look like:
``` ```
int write_data( mbedtls_ssl_context *ssl, int write_data(mbedtls_ssl_context *ssl,
const unsigned char *data_to_write, const unsigned char *data_to_write,
size_t data_to_write_len, size_t data_to_write_len,
size_t *data_written ) size_t *data_written)
{ {
int ret;
*data_written = 0; *data_written = 0;
while( *data_written < data_to_write_len ) while (*data_written < data_to_write_len) {
{ ret = mbedtls_ssl_write(ssl, data_to_write + *data_written,
ret = mbedtls_ssl_write( ssl, data_to_write + *data_written, data_to_write_len - *data_written);
data_to_write_len - *data_written );
if( ret < 0 && if (ret < 0 &&
ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE ) ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
{ return ret;
return( ret );
} }
*data_written += ret; *data_written += ret;
} }
return( 0 ); return 0;
} }
``` ```
where ssl is the SSL context to use, data_to_write the address of the data where ssl is the SSL context to use, data_to_write the address of the data
@ -36,7 +35,7 @@ buffer and data_to_write_len the number of data bytes. The handshake may
not be completed, not even started for the SSL context ssl when the function is not be completed, not even started for the SSL context ssl when the function is
called and in that case the mbedtls_ssl_write() API takes care transparently of called and in that case the mbedtls_ssl_write() API takes care transparently of
completing the handshake before to write and send data to the server. The completing the handshake before to write and send data to the server. The
mbedtls_ssl_write() may not been able to write and send all data in one go thus mbedtls_ssl_write() may not be able to write and send all data in one go thus
the need for a loop calling it as long as there are still data to write and the need for a loop calling it as long as there are still data to write and
send. send.
@ -45,29 +44,28 @@ data sent during the first flight of client messages while the handshake is in
its initial phase, would look completely similar but the call to its initial phase, would look completely similar but the call to
mbedtls_ssl_write_early_data() instead of mbedtls_ssl_write(). mbedtls_ssl_write_early_data() instead of mbedtls_ssl_write().
``` ```
int write_early_data( mbedtls_ssl_context *ssl, int write_early_data(mbedtls_ssl_context *ssl,
const unsigned char *data_to_write, const unsigned char *data_to_write,
size_t data_to_write_len, size_t data_to_write_len,
size_t *data_written ) size_t *data_written)
{ {
int ret;
*data_written = 0; *data_written = 0;
while( *data_written < data_to_write_len ) while (*data_written < data_to_write_len) {
{ ret = mbedtls_ssl_write_early_data(ssl, data_to_write + *data_written,
ret = mbedtls_ssl_write_early_data( ssl, data_to_write + *data_written, data_to_write_len - *data_written);
data_to_write_len - *data_written );
if( ret < 0 && if (ret < 0 &&
ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE ) ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
{ return ret;
return( ret );
} }
*data_written += ret; *data_written += ret;
} }
return( 0 ); return 0;
} }
``` ```
Note that compared to write_data(), write_early_data() can also return Note that compared to write_data(), write_early_data() can also return
@ -81,18 +79,22 @@ early data and then as standard post-handshake application data could
plausibly look like: plausibly look like:
``` ```
ret = write_early_data( ssl, data_to_write, data_to_write_len, ret = write_early_data(ssl,
&early_data_written ); data_to_write,
if( ret < 0 && data_to_write_len,
ret != MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA ) &early_data_written);
{ if (ret < 0 &&
ret != MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA) {
goto error; goto error;
} }
ret = write_data( ssl, data_to_write + early_data_written, ret = write_data(ssl,
data_to_write_len - early_data_written, &data_written ); data_to_write + early_data_written,
if( ret < 0 ) data_to_write_len - early_data_written,
&data_written);
if (ret < 0) {
goto error; goto error;
}
data_written += early_data_written; data_written += early_data_written;
``` ```
@ -100,40 +102,44 @@ data_written += early_data_written;
Finally, taking into account that the server may reject early data, application Finally, taking into account that the server may reject early data, application
code to write and send a buffer of data could plausibly look like: code to write and send a buffer of data could plausibly look like:
``` ```
ret = write_early_data( ssl, data_to_write, data_to_write_len, ret = write_early_data(ssl,
&early_data_written ); data_to_write,
if( ret < 0 && data_to_write_len,
ret != MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA ) &early_data_written);
{ if (ret < 0 &&
ret != MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA) {
goto error; goto error;
} }
/* /*
* Make sure the handshake is completed as it is a requisite to * Make sure the handshake is completed as it is a requisite of
* mbedtls_ssl_get_early_data_status(). * mbedtls_ssl_get_early_data_status().
*/ */
while( !mbedtls_ssl_is_handshake_over( ssl ) ) while (!mbedtls_ssl_is_handshake_over(ssl)) {
{ ret = mbedtls_ssl_handshake(ssl);
ret = mbedtls_ssl_handshake( ssl ); if (ret < 0 &&
if( ret < 0 &&
ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE ) ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
{
goto error; goto error;
} }
} }
ret = mbedtls_ssl_get_early_data_status( ssl ); ret = mbedtls_ssl_get_early_data_status(ssl);
if( ret < 0 ) if (ret < 0) {
goto error; goto error;
}
if( ret == MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED ) if (ret == MBEDTLS_SSL_EARLY_DATA_STATUS_REJECTED) {
early_data_written = 0; early_data_written = 0;
}
ret = write_data( ssl, data_to_write + early_data_written, ret = write_data(ssl,
data_to_write_len - early_data_written, &data_written ); data_to_write + early_data_written,
if( ret < 0 ) data_to_write_len - early_data_written,
&data_written);
if (ret < 0) {
goto error; goto error;
}
data_written += early_data_written; data_written += early_data_written;
``` ```