PR: 2006

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Approved by: steve@openssl.org

Do not use multiple DTLS records for a single user message

diff --git a/ssl/d1_pkt.c b/ssl/d1_pkt.c
index 0f67f77b1daad21fafa0bbd9d59edf23d3aba0c2..ff9253598004aeeef8b6d3e20938532339748507 100644 (file)
--- a/ssl/d1_pkt.c
+++ b/ssl/d1_pkt.c
@@ -1213,7 +1213,6 @@ err:
 int
 dtls1_write_app_data_bytes(SSL *s, int type, const void *buf_, int len)
        {
-       unsigned int n,tot;
        int i;
 
        if (SSL_in_init(s) && !s->in_handshake)
@@ -1227,31 +1226,14 @@ dtls1_write_app_data_bytes(SSL *s, int type, const void *buf_, int len)
                        }
                }
 
-       tot = s->s3->wnum;
-       n = len - tot;
-
-       while( n)
+       if (len > SSL3_RT_MAX_PLAIN_LENGTH)
                {
-               /* dtls1_write_bytes sends one record at a time, sized according to 
-                * the currently known MTU */
-               i = dtls1_write_bytes(s, type, buf_, len);
-               if (i <= 0) return i;
-               
-               if ((i == (int)n) ||
-                       (type == SSL3_RT_APPLICATION_DATA &&
-                               (s->mode & SSL_MODE_ENABLE_PARTIAL_WRITE)))
-                       {
-                       /* next chunk of data should get another prepended empty fragment
-                        * in ciphersuites with known-IV weakness: */
-                       s->s3->empty_fragment_done = 0;
-                       return tot+i;
-                       }
-
-               tot += i;
-               n-=i;
+                       SSLerr(SSL_F_DTLS1_WRITE_APP_DATA_BYTES,SSL_R_DTLS_MESSAGE_TOO_BIG);
+                       return -1;
                }
 
-       return tot;
+       i = dtls1_write_bytes(s, type, buf_, len);
+       return i;
        }
 
 
@@ -1292,46 +1274,13 @@ have_handshake_fragment(SSL *s, int type, unsigned char *buf,
 /* Call this to write data in records of type 'type'
  * It will return <= 0 if not all data has been sent or non-blocking IO.
  */
-int dtls1_write_bytes(SSL *s, int type, const void *buf_, int len)
+int dtls1_write_bytes(SSL *s, int type, const void *buf, int len)
        {
-       const unsigned char *buf=buf_;
-       unsigned int tot,n,nw;
        int i;
-       unsigned int mtu;
 
+       OPENSSL_assert(len <= SSL3_RT_MAX_PLAIN_LENGTH);
        s->rwstate=SSL_NOTHING;
-       tot=s->s3->wnum;
-
-       n=(len-tot);
-
-       /* handshake layer figures out MTU for itself, but data records
-        * are also sent through this interface, so need to figure out MTU */
-#if 0
-       mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_MTU, 0, NULL);
-       mtu += DTLS1_HM_HEADER_LENGTH;  /* HM already inserted */
-#endif
-       mtu = s->d1->mtu;
-
-       if (mtu > SSL3_RT_MAX_PLAIN_LENGTH)
-               mtu = SSL3_RT_MAX_PLAIN_LENGTH;
-
-       if (n > mtu)
-               nw=mtu;
-       else
-               nw=n;
-       
-       i=do_dtls1_write(s, type, &(buf[tot]), nw, 0);
-       if (i <= 0)
-               {
-               s->s3->wnum=tot;
-               return i;
-               }
-
-       if ( (int)s->s3->wnum + i == len)
-               s->s3->wnum = 0;
-       else 
-               s->s3->wnum += i;
-
+       i=do_dtls1_write(s, type, buf, len, 0);
        return i;
        }
 

diff --git a/ssl/ssl.h b/ssl/ssl.h
index 7a554a0a92be5823578e07b6a7eb5e3afc284841..9e2b4394767ebd7afe10d60c03de6a49adca60b2 100644 (file)
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -1898,6 +1898,7 @@ void ERR_load_SSL_strings(void);
 #define SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC       281
 #define SSL_R_DH_PUBLIC_VALUE_LENGTH_IS_WRONG           148
 #define SSL_R_DIGEST_CHECK_FAILED                       149
+#define SSL_R_DTLS_MESSAGE_TOO_BIG                      318
 #define SSL_R_DUPLICATE_COMPRESSION_ID                  309
 #define SSL_R_ECGROUP_TOO_LARGE_FOR_CIPHER              310
 #define SSL_R_ENCRYPTED_LENGTH_TOO_LONG                         150

diff --git a/ssl/ssl_err.c b/ssl/ssl_err.c
index f8f678fb08e6239ef9b48c26402834df325bd8e8..f965463bfa8888b2cfbf95dc3a81cd999cec8ead 100644 (file)
--- a/ssl/ssl_err.c
+++ b/ssl/ssl_err.c
@@ -320,6 +320,7 @@ static ERR_STRING_DATA SSL_str_reasons[]=
 {ERR_REASON(SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC),"decryption failed or bad record mac"},
 {ERR_REASON(SSL_R_DH_PUBLIC_VALUE_LENGTH_IS_WRONG),"dh public value length is wrong"},
 {ERR_REASON(SSL_R_DIGEST_CHECK_FAILED)   ,"digest check failed"},
+{ERR_REASON(SSL_R_DTLS_MESSAGE_TOO_BIG)  ,"dtls message too big"},
 {ERR_REASON(SSL_R_DUPLICATE_COMPRESSION_ID),"duplicate compression id"},
 {ERR_REASON(SSL_R_ECGROUP_TOO_LARGE_FOR_CIPHER),"ecgroup too large for cipher"},
 {ERR_REASON(SSL_R_ENCRYPTED_LENGTH_TOO_LONG),"encrypted length too long"},