[libvirt] [PATCH] conf: Check migration_host is valid or not during libvirt restarts

[chen.fan.fnst at cn.fujitsu.com]

On Fri, 2014-08-29 at 14:52 +0200, Jiri Denemark wrote: 
> On Fri, Aug 29, 2014 at 19:20:58 +0800, Chen Fan wrote:
> > if user specified an invalid strings as migration hostname,
> > like setting: migration_host = "XXXXXXX", libvirt should check
> > it and return error during lbivirt restart.
> > 
> > Signed-off-by: Chen Fan <chen.fan.fnst at cn.fujitsu.com>
> > ---
> >  src/qemu/qemu_conf.c | 40 ++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> > 
> > diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> > index e2ec54f..450ac5b 100644
> > --- a/src/qemu/qemu_conf.c
> > +++ b/src/qemu/qemu_conf.c
> > @@ -33,6 +33,7 @@
> >  #include <fcntl.h>
> >  #include <sys/wait.h>
> >  #include <arpa/inet.h>
> > +#include <netdb.h>
> >  
> >  #include "virerror.h"
> >  #include "qemu_conf.h"
> > @@ -650,6 +651,45 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
> >      GET_VALUE_LONG("seccomp_sandbox", cfg->seccompSandbox);
> >  
> >      GET_VALUE_STR("migration_host", cfg->migrateHost);
> > +    if (cfg->migrateHost) {
> > +        struct addrinfo hints;
> > +        struct addrinfo *res;
> > +
> > +        memset(&hints, 0, sizeof(hints));
> > +        hints.ai_flags = AI_ADDRCONFIG;
> > +        hints.ai_family = AF_UNSPEC;
> > +
> > +        if (getaddrinfo(cfg->migrateHost, NULL, &hints, &res) != 0) {
> > +            virReportError(VIR_ERR_CONF_SYNTAX,
> > +                           _("migration_host: '%s' is not a valid hostname"),
> > +                           cfg->migrateHost);
> > +            goto cleanup;
> > +        }
> > +
> > +        if (res == NULL) {
> > +            virReportError(VIR_ERR_CONF_SYNTAX,
> > +                           _("No IP address for host '%s' found"),
> > +                           cfg->migrateHost);
> > +            goto cleanup;
> > +        }
> > +
> > +        freeaddrinfo(res);
> 
> I don't think this is a good idea. What if it's in fact valid and just
> can't be resolved due to a temporary issue? It should only fail at the
> time someone actually tries to migrate a domain.

What are these issues? usually, I think migration hosts always at the
same network, a valid hostname should be resolved by DNS. if can't be
resolved, libvirt should tell user the error at the time of libvirt
restart, Maybe we can output a warning or info to let user know that but
restart failure. what do you think?

Thanks,
Chen


> 
> > +
> > +        if (STRPREFIX(cfg->migrateHost, "localhost")) {
> > +            virReportError(VIR_ERR_CONF_SYNTAX, "%s",
> > +                           _("setting migration_host to 'localhost' is not allowed"));
> > +            goto cleanup;
> > +        }
> > +
> > +        if (STREQ(cfg->migrateHost, "127.0.0.1") ||
> > +            STREQ(cfg->migrateHost, "::1")) {
> > +            virReportError(VIR_ERR_CONF_SYNTAX, "%s",
> > +                           _("setting migration_host to '127.0.0.1' or '::1' "
> > +                             "is not allowed"));
> > +            goto cleanup;
> > +        }
> > +    }
> > +
> 
> Checking for localhost could make sense.
> 
> >      GET_VALUE_STR("migration_address", cfg->migrationAddress);
> >  
> >      GET_VALUE_BOOL("log_timestamp", cfg->logTimestamp);
> 
> Jirka