On 07.03.2018 04:39, Alexey Kardashevskiy wrote:
> On 08/02/18 15:29, Alexey Kardashevskiy wrote:
>> On 01/02/18 20:36, Alexey Kardashevskiy wrote:
>>> If we run QEMU with -netdev user,id=USER0,hostfwd=tcp::2222-:22, it starts
>>> a DHCP server and starts allocating client IPs from 10.0.2.15 so
>>> this is what the guest normally receives. Since QEMU automatically adds
>>> the DHCP starting address into the forwarding table, everything works.
>>> This is the table before guest started:
>>>
>>> (qemu) info usernet
>>> VLAN -1 (USER0):
>>> Protocol[State] FD Source Address Port Dest. Address Port RecvQ
>>> SendQ
>>> TCP[HOST_FORWARD] 11 * 2222 10.0.2.15 22 0
>>> 0
>>>
>>> However if the guest happens to have DHCP lease (for example, 10.0.2.16),
>>> the forwarding stops working. The guest can still reach the outer world
>>> (which is expected).
>>>
>>> This updates the forwarding table when QEMU confirms the requested IP
>>> to the guest.
>>>
>>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
>>> ---
>>>
>>> Does this look any useful?
>
> Ping, anyone?
Maybe you should make sure to put the SLIRP maintainer on CC: ?
>>
>>
>> It does not seem like it does very much but .... :)
>>
>>
>>>
>>> Sure I can remove /var/lib/dhcp/dhclient.enp0s1.leases in the guest or
>>> start QEMU with the DHCP start address equal to what the guest wants to
>>> reserve but it is quite confusing why such a simple config just does not
>>> work.
>>>
>>> Found this with the brand new Ubuntu 17.10 which runs dhcp and something
>>> called "netplan" and the guest ends up with 2 IPs from 10.0.2.x network.
>>> After disabling netplan, the lease remains and it is not 10.0.2.15 but
>>> rather .16 or .17.
>>>
>>> Comments? Thanks.
>>>
>>> ---
>>> slirp/libslirp.h | 2 ++
>>> slirp/bootp.c | 2 ++
>>> slirp/slirp.c | 27 +++++++++++++++++++++++++++
>>> 3 files changed, 31 insertions(+)
>>>
>>> diff --git a/slirp/libslirp.h b/slirp/libslirp.h
>>> index 540b3e5..6779081 100644
>>> --- a/slirp/libslirp.h
>>> +++ b/slirp/libslirp.h
>>> @@ -33,6 +33,8 @@ int slirp_add_hostfwd(Slirp *slirp, int is_udp,
>>> struct in_addr guest_addr, int guest_port);
>>> int slirp_remove_hostfwd(Slirp *slirp, int is_udp,
>>> struct in_addr host_addr, int host_port);
>>> +void slirp_update_hostfwd(Slirp *slirp, struct in_addr old_guest_addr,
>>> + struct in_addr new_guest_addr);
>>> int slirp_add_exec(Slirp *slirp, int do_pty, const void *args,
>>> struct in_addr *guest_addr, int guest_port);
>>>
>>> diff --git a/slirp/bootp.c b/slirp/bootp.c
>>> index 5dd1a41..5876004 100644
>>> --- a/slirp/bootp.c
>>> +++ b/slirp/bootp.c
>>> @@ -225,6 +225,8 @@ static void bootp_reply(Slirp *slirp, const struct
>>> bootp_t *bp)
>>> /* Update ARP table for this IP address */
>>> arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);
>>>
>>> + slirp_update_hostfwd(slirp, slirp->vdhcp_startaddr, daddr.sin_addr);
>>> +
>>> saddr.sin_addr = slirp->vhost_addr;
>>> saddr.sin_port = htons(BOOTP_SERVER);
>>>
>>> diff --git a/slirp/slirp.c b/slirp/slirp.c
>>> index 1cb6b07..a9d8a16 100644
>>> --- a/slirp/slirp.c
>>> +++ b/slirp/slirp.c
>>> @@ -1061,6 +1061,33 @@ int slirp_add_hostfwd(Slirp *slirp, int is_udp,
>>> struct in_addr host_addr,
>>> return 0;
>>> }
>>>
>>> +static void slirp_do_update_hostfwd(Slirp *slirp, struct socket *head,
>>> + struct in_addr old_guest_addr,
>>> + struct in_addr new_guest_addr)
>>> +{
>>> + struct socket *so;
>>> + char oldaddr[17], newaddr[17];
>>> +
>>> + for (so = head->so_next; so != head; so = so->so_next) {
>>> + if ((so->so_state & SS_HOSTFWD) &&
>>> + so->lhost.sin.sin_addr.s_addr == old_guest_addr.s_addr) {
>>> + strncpy(oldaddr, inet_ntoa(old_guest_addr), sizeof(oldaddr) -
>>> 1);
>>> + strncpy(newaddr, inet_ntoa(new_guest_addr), sizeof(newaddr) -
>>> 1);
>>> + DEBUG_ARGS((dfd, "Updating forwarding from %s:%d to %s:%d\n",
>>> + oldaddr, ntohs(so->lhost.sin.sin_port),
>>> + newaddr, ntohs(so->lhost.sin.sin_port)));
>>> + so->lhost.sin.sin_addr = new_guest_addr;
>>> + }
>>> + }
>>> +}
>>> +
>>> +void slirp_update_hostfwd(Slirp *slirp, struct in_addr old_guest_addr,
>>> + struct in_addr new_guest_addr)
>>> +{
>>> + slirp_do_update_hostfwd(slirp, &slirp->udb, old_guest_addr,
>>> new_guest_addr);
>>> + slirp_do_update_hostfwd(slirp, &slirp->tcb, old_guest_addr,
>>> new_guest_addr);
>>> +}
>>> +
>>> int slirp_add_exec(Slirp *slirp, int do_pty, const void *args,
>>> struct in_addr *guest_addr, int guest_port)
>>> {
>>>
>>
>>
>
>
