tests: Fix test-commands test case failures.

[ossama-othman]

Correct several issues with the test-commands unit test:

• Existing MPTCP address IDs are ignored.
  • The current test-commands unit test assumes that it can use hard-coded MPTCP address ID test values, but that could fail if the same address ID is currently in use by the in-kernel path manager. Leverage the mptcpd global MPTCP address ID manager to generate an ID suitable for the test since it attempts to stay in sync with the kernel.
• The mptcpd_kpm_add_addr() test case always fails.
  • Fix mptcpd_kpm_add_addr() test failures by explicitly binding the test IPv4 address to a network interface (loopback).
• mptcpd_kpm_flush_addrs() was called too early.
  • MPTCP addresses were flushed before get_addrs test case, causing the latter to fail due to all MPTCP addresses being purged from the in-kernel MPTCP path manager prior to retrieval of the test addresses.

[ossama-othman]

PR #171 will be leveraged by this pull requested once it is merged to master.

[coveralls]

Pull Request Test Coverage Report for Build 1647641308

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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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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.9%) to 50.922%

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Totals
Change from base Build 1584597976:	2.9%
Covered Lines:	1077
Relevant Lines:	2115

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💛 - Coveralls

[mjmartineau]

Just one grammar nit, I don't have any other suggestions right now. Will watch for updates w.r.t. #171

[ossama-othman]

With these changes in place the full set of test cases in the test-commands unit test now pass when run as root or with the CAP_NET_ADMIN capability. Test cases that require CAP_NET_ADMIN but run as an unprivileged user still fail as expected. Failures in that cases are ignored.

The test suite was run with the following set of commands:

• Unprivileged user
  • make check
• root user
  • sudo make check
• Unprivileged user with CAP_NET_ADMIN capability
  • sudo capsh --caps="cap_net_admin+eip cap_setpcap,cap_setuid,cap_setgid+ep" --keep=1 --user=$USER --addamb=cap_net_admin -- -c "make check"

There is one caveat to keep in mind when running make check or just the test-commands unit test after a privileged test run: the get_limits test case assumes that the subflows and add_addr_accepted MPTCP limits are always zero when not run as root, which is not true after the privileged test run, resulting in failure. MPTCP limits should be reset to zero between privileged and unprivileged test runs, e.g.:

$ sudo make check
$ sudo ip mptcp limits set subflows 0 add_addr_accepted 0
$ make check

Ideally, the test should retrieve and store existing MPTCP limits prior to running the set_limits test case, and then restore the original limits before process exit. Such a change should be done in a separate pull request since this patch set is already rather large.

[ossama-othman]

I also tried to run tests in the mptcpd GitHub workflows as root but the test-commands unit test failed for some reason. Log messages for the test-commands unit test (e.g. tests/test-commands.log or tests/test-suite.log) wasn't readily available in the GitHub ubuntu-latest environment so I'll attempt enable such privileged test runs and dump those log files in the existing mptcpd GitHub workflows in a separate pull request.

[mjmartineau]

Looks good to me. Tried building/running with ELL 0.30 and recent master branch (although I modified the recent ELL to deal with the warnings, unrelated to this PR).