To prevent dropping the same message over and over again, the UDP proxy
test application programs/test/udp_proxy _logically_ maintains a mapping
from records to the number of times the record has already been dropped,
and stops dropping once a configurable threshold (currently 2) is passed.
However, the actual implementation deviates from this logical view
in two crucial respects:
- To keep the implementation simple and independent of
implementations of suitable map interfaces, it only counts how
many times a record of a given _size_ has been dropped, and
stops dropping further records of that size once the configurable
threshold is passed. Of course, this is not fail-proof, but a
good enough approximation for the proxy, and it allows to use
an inefficient but simple array for the required map.
- The implementation mixes datagram lengths and record lengths:
When deciding whether it is allowed to drop a datagram, it
uses the total datagram size as a lookup index into the map
counting the number of times a package has been dropped. However,
when updating this map, the UDP proxy traverses the datagram
record by record, and updates the mapping at the level of record
lengths.
Apart from this inconsistency, the current implementation suffers
from a lack of bounds checking for the parsed length of incoming
DTLS records that can lead to a buffer overflow when facing
malformed records.
This commit removes the inconsistency in datagram vs. record length
and resolves the buffer overflow issue by not attempting any dissection
of datagrams into records, and instead only counting how often _datagrams_
of a particular size have been dropped.
There is only one practical situation where this makes a difference:
If datagram packing is used by default but disabled on retransmission
(which OpenSSL has been seen to do), it can happen that we drop a
datagram in its initial transmission, then also drop some of its records
when they retransmitted one-by-one afterwards, yet still keeping the
drop-counter at 1 instead of 2. However, even in this situation, we'll
correctly count the number of droppings from that point on and eventually
stop dropping, because the peer will not fall back to using packing
and hence use stable record lengths.
When running make with parallelization, running both "clean" and "lib"
with a single make invocation can lead to each target building in
parallel. It's bad if lib is partially done building something, and then
clean deletes what was built. This can lead to errors later on in the
lib target.
$ make -j9 clean lib
CC aes.c
CC aesni.c
CC arc4.c
CC aria.c
CC asn1parse.c
CC ./library/error.c
CC ./library/version.c
CC ./library/version_features.c
AR libmbedcrypto.a
ar: aes.o: No such file or directory
Makefile:120: recipe for target 'libmbedcrypto.a' failed
make[2]: *** [libmbedcrypto.a] Error 1
Makefile:152: recipe for target 'libmbedcrypto.a' failed
make[1]: *** [libmbedcrypto.a] Error 2
Makefile:19: recipe for target 'lib' failed
make: *** [lib] Error 2
make: *** Waiting for unfinished jobs....
To avoid this sort of trouble, always invoke clean by itself without
other targets throughout the library. Don't run clean in parallel with
other rules. The only place where clean was run in parallel with other
targets was in list-symbols.sh.
* origin/pr/2649:
list-symbols.sh: if the build fails, print the build transcript
Document "check-names.sh -v"
all.sh: invoke check-names.sh in print-trace-on-exit mode
Print a command trace if the check-names.sh exits unexpectedly
* origin/pr/2612:
Adjust backport's documentation to account for missing features
Backport a doxygen note from development for `mbedtls_ssl_conf_max_frag_len()`
Update change log
Reword ssl_conf_max_frag_len documentation for clarity
We've observed that sometimes check-names.sh exits unexpectedly with
status 2 and no error message. The failure is not reproducible. This
commits makes the script print a trace if it exits unexpectedly.
* origin/pr/2494:
Ignore more generated files: seedfile, apidoc
Improve .gitignore grouping and documentation
Generate tags for Vi, for Emacs and with Global
Enabling the USE_CRYPTO_SUBMODULE option causes problems if the
crypto submodule isn't present. For example, when building
mbed-crypto as a submodule, it should use error.c from the parent
project if USE_CRYPTO_SUBMODULE is set. However if the parent
project isn't present, then the build will fail. Only enable it
if the submodule actually exists.
* origin/pr/2546: (31 commits)
Add documentation for why we're catching all exceptions
Use check_output instead of Popen
Start unused variable with underscore
Correct documentation
Check that the report directory is a directory
Use namespaces instead of full classes
Fix pylint issues
Don't put abi dumps in subfolders
Add verbose switch to silence all output except the final report
Fetch the remote crypto branch, rather than cloning it
Prefix internal functions with underscore
Add RepoVersion class to make handling of many arguments easier
Reduce indentation levels
Improve documentation
Use optional arguments for setting repositories
Only build the library
Add ability to compare submodules from different repositories
Add handling for cases when not all .so files are present
Extend functionality to allow setting crypto submodule version
Simplify logic for checking if report folder can be removed
...
When doing ABI/API checking, its useful to have a list of all the
identifiers that are defined in the internal header files, as we
do not promise compatibility for them. This option allows for a
simple method of getting them for use with the ABI checking script.
There are a number of arguments being passed around, nearly all of
which are duplicated between the old and new versions. Moving these
into a separate class should hopefully make it simpler to follow
what is being done.
As before with wanting to compare revisions across different
repositories, the ability to select the crypto submodule from a
different repository is useful.
We may wish to compare ABI/API between Mbed TLS and Mbed Crypto,
which will cause issues as not all .so files are shared. Only
compare .so files which both libraries have.
As going forward we will have Crypto in a submodule, we will need to
be able to check ABI compatibility between versions using different
submodule versions. For TLS versions that support the submodule, we
will always build using the submodule.
If the Crypto submodule is used, libmbedcrypto.so is not in the main
library folder, but in crypto/library instead. Given this, the script
searches for *.so files and notes their path, in order to create the
dumps correctly.
By default abi-compliance-checker will check the entire ABI/API.
There are internal identifiers that we do not promise compatibility
for, so we want the ability to skip them when checking the ABI/API.
