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Remove BIO_CTRL_DGRAM_MTU_EXCEEDED retry in dtls1_do_write.

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The retry doesn't actually work when we're sending a non-initial fragment; the
s->init_off != 0 block will get re-run each iteration through and continually
prepend headers. It can also infinite loop if the BIO reports
BIO_CTRL_DGRAM_MTU_EXCEEDED but either fails to report an MTU or reports an MTU
that always rounds up to the minimum. See upstream's
d3d9eef31661633f5b003a9e115c1822f79d1870.

WebRTC doesn't participate in any of the MTU logic and inherits the default
MTU, so just remove it for now.

Change-Id: Ib2ed2ba016b7c229811741fb7369c015ba0b551f
Reviewed-on: https://boringssl-review.googlesource.com/2827
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2015-01-11 19:25:32 -05:00 committed by Adam Langley
parent 7f18b139cc
commit 5a3cc0381b
1 changed files with 23 additions and 31 deletions
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54
ssl/d1_both.c
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@ -286,6 +286,8 @@ int dtls1_do_write(SSL *s, int type) {
/* XDTLS: this function is too long. split out the CCS part */
if (type == SSL3_RT_HANDSHAKE) {
/* If this isn't the first fragment, reserve space to prepend a new
* fragment header. This will override the body of a previous fragment. */
if (s->init_off != 0) {
assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
s->init_off -= DTLS1_HM_HEADER_LENGTH;
@ -321,38 +323,28 @@ int dtls1_do_write(SSL *s, int type) {
ret = dtls1_write_bytes(s, type, &s->init_buf->data[s->init_off], len);
if (ret < 0) {
/* might need to update MTU here, but we don't know which previous packet
* caused the failure -- so can't really retransmit anything. continue
* as if everything is fine and wait for an alert to handle the
* retransmit. */
if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) &&
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0) {
s->d1->mtu =
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
} else {
return -1;
}
} else {
/* bad if this assert fails, only part of the handshake message got sent.
* But why would this happen? */
assert(len == (unsigned int)ret);
if (ret == s->init_num) {
if (s->msg_callback) {
s->msg_callback(1, s->version, type, s->init_buf->data,
(size_t)(s->init_off + s->init_num), s,
s->msg_callback_arg);
}
s->init_off = 0; /* done writing this message */
s->init_num = 0;
return 1;
}
s->init_off += ret;
s->init_num -= ret;
frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
return -1;
}
/* bad if this assert fails, only part of the handshake message got sent.
* But why would this happen? */
assert(len == (unsigned int)ret);
if (ret == s->init_num) {
if (s->msg_callback) {
s->msg_callback(1, s->version, type, s->init_buf->data,
(size_t)(s->init_off + s->init_num), s,
s->msg_callback_arg);
}
s->init_off = 0; /* done writing this message */
s->init_num = 0;
return 1;
}
s->init_off += ret;
s->init_num -= ret;
frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
}
return 0;