util/qemu-sockets: Introduce inet socket options controlling TCP keep-alive
JIRA: https://issues.redhat.com/browse/RHEL-67706
This series extends the work introduced by commit aec21d31 ("qapi: Add InetSocketAddress member keep-alive"). 1
First, the series fixes an issue in qio_dns_resolver_lookup_sync_inet(), where the InetSocketAddress structure is only partially copied. Next, it refactors setting client socket options into a separate function and the success and failure paths in inet_listen_saddr() in preparation for keep-alive support on server sockets and the addition of new TCP keep-alive options.
Then, the series extends the support for keep-alive on server sockets.
Before adding new inet address options, there are a couple of issues with the inet address options parsing this series resolves:
- the parser contains a bug where it does not allow options with names that start with the name of another flag,
- the parser lacks some common function for parsing numeric values,
- the parser supports only a subset of the inet address options, namely the 'numeric' flag is missing. This is resolved by the sixth patch by reworking with parser using the QemuOpts parser. The series also includes unit tests to verify, there is no regression in the refactored parser.
Finally, the series introduces three new InetSocketAddress options for the control of TCP keep-alive settings. By default, the value of all new settings is 0, which means no custom socket option value is set.
This is useful, for example, for live migration. In case there is no traffic from the destination to the source machine during postcopy, the destination cannot detect a failed connection due to a lack of non-acknowledged packets and stays in the postcopy-active state until paused by the management of the QEMU instance.
Signed-off-by: Juraj Marcin jmarcin@redhat.com