configuration: Fix addr/notify flag string leaks.

[ossama-othman]

Fix memory leaks that occured when parsing the "addr-flags" and
"notify-flags" entries in the mptcpd configuration file. The string
returned from the ELL l_settings_get_string() function is dynamically
allocated and must be deallocated with l_free().

Reported-by: Mat Martineau mathew.j.martineau@linux.intel.com

[ossama-othman]

Steps to reproduce:

1. ./bootstrap
2. ./configure --prefix=/usr/local
3. make
4. sudo make install
5. sudo vi /usr/local/etc/mptcpd/mptcpd.conf # uncomment addr-flags and notify-flags entries
6. LD_LIBRARY_PATH=/usr/local/lib valgrind --leak-check=full /usr/local/libexec/mptcpd
7. CTRL-c # Stop mptcpd
8. sudo make uninstall

Leaks detected by Valgrind before applying patch:

==753501== HEAP SUMMARY:
==753501==     in use at exit: 47 bytes in 2 blocks
==753501==   total heap usage: 229 allocs, 227 frees, 58,188 bytes allocated
==753501== 
==753501== 8 bytes in 1 blocks are definitely lost in loss record 1 of 2
==753501==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==753501==    by 0x487AA91: l_malloc (util.c:62)
==753501==    by 0x487E508: unescape_value (settings.c:196)
==753501==    by 0x10C3A8: parse_config_addr_flags (configuration.c:573)
==753501==    by 0x10C512: parse_config_file (configuration.c:675)
==753501==    by 0x10C5C9: parse_config_files (configuration.c:723)
==753501==    by 0x10C9C4: mptcpd_config_create (configuration.c:823)
==753501==    by 0x10BC19: main (mptcpd.c:51)
==753501== 
==753501== 39 bytes in 1 blocks are definitely lost in loss record 2 of 2
==753501==    at 0x4848899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==753501==    by 0x487AA91: l_malloc (util.c:62)
==753501==    by 0x487E508: unescape_value (settings.c:196)
==753501==    by 0x10C338: parse_config_notify_flags (configuration.c:592)
==753501==    by 0x10C504: parse_config_file (configuration.c:672)
==753501==    by 0x10C5C9: parse_config_files (configuration.c:723)
==753501==    by 0x10C9C4: mptcpd_config_create (configuration.c:823)
==753501==    by 0x10BC19: main (mptcpd.c:51)
==753501== 
==753501== LEAK SUMMARY:
==753501==    definitely lost: 47 bytes in 2 blocks
==753501==    indirectly lost: 0 bytes in 0 blocks
==753501==      possibly lost: 0 bytes in 0 blocks
==753501==    still reachable: 0 bytes in 0 blocks
==753501==         suppressed: 0 bytes in 0 blocks
==753501== 
==753501== For lists of detected and suppressed errors, rerun with: -s
==753501== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)

Valgrind results after applying the patch:

==754343== 
==754343== HEAP SUMMARY:
==754343==     in use at exit: 0 bytes in 0 blocks
==754343==   total heap usage: 231 allocs, 231 frees, 58,220 bytes allocated
==754343== 
==754343== All heap blocks were freed -- no leaks are possible
==754343== 
==754343== For lists of detected and suppressed errors, rerun with: -s
==754343== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

[coveralls]

Pull Request Test Coverage Report for Build 2627152348

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 4 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.07%) to 62.277%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/configuration.c	0	4	0.0%

Totals
Change from base Build 2626644661:	-0.07%
Covered Lines:	1187
Relevant Lines:	1906

---

💛 - Coveralls