Commit c27807dd authored by Manuel Pégourié-Gonnard's avatar Manuel Pégourié-Gonnard
Browse files

Make SSL_BUFFER_LEN overhead depend more on config

parent 31855456
......@@ -249,7 +249,9 @@
* Note: the RFC defines the default size of SSL / TLS messages. If you
* change the value here, other clients / servers may not be able to
* communicate with you anymore. Only change this value if you control
* both sides of the connection and have it reduced at both sides!
* both sides of the connection and have it reduced at both sides, or
* if you're using the Max Fragment Length extension and you know all your
* peers are using it too!
*/
#if !defined(SSL_MAX_CONTENT_LEN)
#define SSL_MAX_CONTENT_LEN 16384 /**< Size of the input / output buffer */
......@@ -258,8 +260,8 @@
/* \} name SECTION: Module settings */
/*
* Allow an extra 301 bytes for the record header and encryption overhead:
* counter (8) + header (5) + IV(16) + MAC (48) + padding (256)
* Allow extra bytes for record, authentication and encryption overhead:
* counter (8) + header (5) + IV(16) + MAC (16-48) + padding (0-256)
* and allow for a maximum of 1024 of compression expansion if
* enabled.
*/
......@@ -269,8 +271,36 @@
#define SSL_COMPRESSION_ADD 0
#endif
#define SSL_BUFFER_LEN (SSL_MAX_CONTENT_LEN + SSL_COMPRESSION_ADD + 333)
#if defined(POLARSSL_RC4_C) || defined(POLARSSL_CIPHER_MODE_CBC)
/* Ciphersuites using HMAC */
#if defined(POLARSSL_SHA512_C)
#define SSL_MAC_ADD 48 /* SHA-384 used for HMAC */
#elif defined(POLARSSL_SHA256_C)
#define SSL_MAC_ADD 32 /* SHA-256 used for HMAC */
#else
#define SSL_MAC_ADD 20 /* SHA-1 used for HMAC */
#endif
#else
/* AEAD ciphersuites: GCM and CCM use a 128 bits tag */
#define SSL_MAC_ADD 16
#endif
#if defined(POLARSSL_CIPHER_MODE_CBC)
#define SSL_PADDING_ADD 256
#else
#define SSL_PADDING_ADD 0
#endif
#define SSL_BUFFER_LEN ( SSL_MAX_CONTENT_LEN \
+ SSL_COMPRESSION_ADD \
+ 29 /* counter + header + IV */ \
+ SSL_MAC_ADD \
+ SSL_PADDING_ADD \
)
/*
* Signaling ciphersuite values (SCSV)
*/
#define SSL_EMPTY_RENEGOTIATION_INFO 0xFF /**< renegotiation info ext */
/*
......
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