Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Make switch_tcpdump more robust and user-friendly #192

Merged
merged 8 commits into from
May 13, 2024
Merged

Make switch_tcpdump more robust and user-friendly #192

merged 8 commits into from
May 13, 2024

Commits on May 10, 2024

  1. switch_tcpdump: change error exit code 

    The tcpdump program uses exit status 1 (which is then passed back to the
user via switch_tcpdump) to signal most common errors, and it does not
use exit status 2.

Have switch_tcpdump use exit status 2 to make it easier to identify the
source of an error.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    db62d59 View commit details
    Browse the repository at this point in the history

  2. switch_tcpdump: flush print output immediately 

    Make sure switch_tcpdump messages printed prior to starting tcpdump are
flushed before the tcpdump output. Otherwise, the console output may
look quite confusing.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    3bd4c74 View commit details
    Browse the repository at this point in the history

  3. switch_tcpdump: allow unlimited filesize 

    Allow setting --maxSize to 0 to have unlimited file size. This lets the
user skip all the system calls associated with checking the file size
frequently.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    144da2e View commit details
    Browse the repository at this point in the history

  4. switch_tcpdump: capture output from ofdpa_acl_flow_cli 

    There are two error messages from /usr/sbin/ofdpa_acl_flow_cli.py
that a switch_tcpdump user is likely to encounter at some point.

When trying to add the ACL rule which already exists:

  Error from ofdpaFlowAdd(). rc = -25

When trying to remove the ACL rule when it does not exist:

  Error from ofdpaFlowDelete(). rc = -30

These error message provide little useful information to the user,
and they cannot be prevented entirely (consider, for instance, running
switch_tcpdump after terminating it with signal 9). Catch them and show
only messages for unexpected errors.

Also turn the returncode values (e.g., 231) into signed int (e.g., -25).
The function caller can still choose to handle the rc values as they see
fit.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    5f731de View commit details
    Browse the repository at this point in the history

  5. switch_tcpdump: deal with missing/present acl rules automatically 

    When shutting down, ignore the error returned by rule_delete if
the ACL rule is already gone. It is not a problem.

When starting up and receiving an error from rule_insert because a
colliding ACL rule is already present (presumably the same one), just
remove the rule (to be sure) and insert it again (instead of aborting
with an error).

Both changes should make switch_tcpdump more user-friendly.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    50ba5be View commit details
    Browse the repository at this point in the history

  6. switch_tcpdump: add custom signal handler 

    Add a custom signal handler that deletes the ACL rule immediately.
Attach the handler to signals INT and TERM (to have it called when the
user hits Ctrl-C or the program ends any other way).

At the end of the handler, raise KeyboardInterrupt to ensure the tcpdump
process is terminated (if it hasn't been already).

Note that we can disable signals in rule_delete because they get
re-enabled when the custom signal handler is installed (and we don't
care to receive further signals when rule_delete is called during
process termination).

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    cc7b3c3 View commit details
    Browse the repository at this point in the history

  7. switch_tcpdump: update usage examples and usage description 

    Eliminate misleading "ingress packets" which wrongly suggests that only
ingress packets are visible, even though packets originating from the
switch (and therefore being seen by the Linux kernel) are also captured
when sent through the --inPort interface.

Tweak first example to demonstrate the default 100 MB filesize limit,
and add a second example to show how to remove the filesize limit.

Change final usage example to include additional, typical extra
arguments that are passed to tcpdump.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    37d7212 View commit details
    Browse the repository at this point in the history

  8. Add man page for switch_tcpdump(8) 

    Add a man page for switch_tcpdump which provides information that does
not easily fit into the usage message.

Formatting for the new man page is based on the tcpdump(8) man page.

Mention the man page in the program help text to help users find it.

Signed-off-by: Roger Luethi <roger.luethi@bisdn.de>
    @ideaship
    ideaship committed May 10, 2024
    Configuration menu
    Copy the full SHA
    251d382 View commit details
    Browse the repository at this point in the history