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On Sat, Aug 3, 2019 at 7:37 PM Mike Gilbert <floppym@g.o> wrote: |
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> |
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> On Sat, Aug 3, 2019 at 3:30 PM Zac Medico <zmedico@g.o> wrote: |
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> > |
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> > Add _has_ipv6() function and use it in _configure_loopback_interface() |
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> > to decide whether to add an IPv6 address. |
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> > |
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> > Bug: https://bugs.gentoo.org/691290 |
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> > --- |
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> > lib/portage/process.py | 40 +++++++++++++++++++++++++++++++++++++--- |
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> > 1 file changed, 37 insertions(+), 3 deletions(-) |
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> > |
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> > diff --git a/lib/portage/process.py b/lib/portage/process.py |
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> > index 690421815..ca8b0c172 100644 |
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> > --- a/lib/portage/process.py |
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> > +++ b/lib/portage/process.py |
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> > @@ -339,6 +339,9 @@ def spawn(mycommand, env=None, opt_name=None, fd_pipes=None, returnpid=False, |
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> > fd_pipes[1] = pw |
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> > fd_pipes[2] = pw |
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> > |
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> > + # Cache _has_ipv6() result for use in child processes. |
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> > + _has_ipv6() |
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> > + |
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> > # This caches the libc library lookup and _unshare_validator results |
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> > # in the current process, so that results are cached for use in |
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> > # child processes. |
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> > @@ -446,6 +449,38 @@ def spawn(mycommand, env=None, opt_name=None, fd_pipes=None, returnpid=False, |
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> > # Everything succeeded |
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> > return 0 |
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> > |
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> > +__has_ipv6 = None |
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> > + |
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> > +def _has_ipv6(): |
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> > + """ |
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> > + Test that both userland and kernel support IPv6, by attempting |
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> > + to create a socket and listen on any unused port of the IPv6 |
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> > + ::1 loopback address. |
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> > + |
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> > + @rtype: bool |
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> > + @return: True if IPv6 is supported, False otherwise. |
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> > + """ |
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> > + global __has_ipv6 |
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> > + |
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> > + if __has_ipv6 is None: |
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> > + if socket.has_ipv6: |
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> > + sock = None |
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> > + try: |
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> > + # python2.7 sockets do not support context management protocol |
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> > + sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM) |
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> > + sock.bind(('::1', 0)) |
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> > + except EnvironmentError: |
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> > + __has_ipv6 = False |
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> > + else: |
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> > + __has_ipv6 = True |
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> > + finally: |
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> > + if sock is not None: |
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> > + sock.close() |
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> > + else: |
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> > + __has_ipv6 = False |
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> > + |
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> > + return __has_ipv6 |
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> > + |
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> > def _configure_loopback_interface(): |
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> > """ |
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> > Configure the loopback interface. |
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> > @@ -478,9 +513,8 @@ def _configure_loopback_interface(): |
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> > |
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> > try: |
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> > subprocess.call(['ip', 'address', 'add', '10.0.0.1/8', 'dev', 'lo']) |
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> > - with open(os.devnull, 'wb', 0) as devnull: |
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> > - subprocess.call(['ip', 'address', 'add', 'fd00::1/8', 'dev', 'lo'], |
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> > - stdout=devnull, stderr=devnull) |
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> > + if _has_ipv6(): |
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> > + subprocess.call(['ip', 'address', 'add', 'fd00::1/8', 'dev', 'lo']) |
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> > except EnvironmentError as e: |
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> > writemsg("Error calling 'ip': %s\n" % e.strerror, noiselevel=-1) |
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> > |
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> > -- |
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> > 2.21.0 |
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> > |
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> |
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> This seems reasonable, though I don't have an IPv6-less system to test it on. |
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|
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While chatting in #gentoo-desktop, we found that it is possible to |
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have IPv6 enabled, but prohibit IPv6 addresses from being added to |
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interfaces. This produces the following error from ip: |
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|
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RTNETLINK answers: Permission denied |
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|
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https://www.kernel.org/doc/Documentation/networking/ipv6.txt |
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|
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ipv6.disabled = 0 |
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ipv6.disable_ipv6 = 1 |
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|
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I don't think your __has_ipv6 function will catch this. |