Re: [Qemu-devel] [PATCH v3] slirp: Handle whole 127.0.0.0/8 network as local addresses.

[Jan Kiszka]

On 2012-07-13 22:54, Anders Waldenborg wrote:
> Changes so translation of remote address to the host's ip address in
> the virtual network happens for all addresses in the 127.0.0.0/8
> network, not just 127.0.0.1.
> 
> This fixes so that hostfwd bound to addresses such as 127.0.0.2 works.
> 
> Signed-off-by: Anders Waldenborg <address@hidden>
> ---
> 
> On Fri, Jul 13, 2012 at 03:01:14PM +0000, Blue Swirl wrote:
>>> Notice that the surrounding code in tcp_subr.c uses tabs for
>>> indentation. Should I still use space as the coding style mandates
>>> (and which makes checkpatch happy)?
>>
>> Yes, the goal is to get rid of tabs.
> 
> OK. Thanks for clarifacion and review!
> 
> Patch updated.
> 
>  slirp/main.h     |    1 +
>  slirp/slirp.c    |    3 +++
>  slirp/tcp_subr.c |    7 +++++--
>  3 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/slirp/main.h b/slirp/main.h
> index 028df4b..bf601e2 100644
> --- a/slirp/main.h
> +++ b/slirp/main.h
> @@ -31,6 +31,7 @@ extern char *exec_shell;
>  extern u_int curtime;
>  extern fd_set *global_readfds, *global_writefds, *global_xfds;
>  extern struct in_addr loopback_addr;
> +extern in_addr_t loopback_mask;
>  extern char *username;
>  extern char *socket_path;
>  extern int towrite_max;
> diff --git a/slirp/slirp.c b/slirp/slirp.c
> index 90473eb..9787104 100644
> --- a/slirp/slirp.c
> +++ b/slirp/slirp.c
> @@ -29,6 +29,8 @@
>  
>  /* host loopback address */
>  struct in_addr loopback_addr;
> +/* host loopback network mask */
> +in_addr_t loopback_mask;
>  
>  /* emulated hosts use the MAC addr 52:55:IP:IP:IP:IP */
>  static const uint8_t special_ethaddr[ETH_ALEN] = {
> @@ -191,6 +193,7 @@ static void slirp_init_once(void)
>  #endif
>  
>      loopback_addr.s_addr = htonl(INADDR_LOOPBACK);
> +    loopback_mask = htonl(IN_CLASSA_NET);
>  }
>  
>  static void slirp_state_save(QEMUFile *f, void *opaque);
> diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
> index 0a545c4..6b01f74 100644
> --- a/slirp/tcp_subr.c
> +++ b/slirp/tcp_subr.c
> @@ -435,8 +435,11 @@ tcp_connect(struct socket *inso)
>       so->so_fport = addr.sin_port;
>       so->so_faddr = addr.sin_addr;
>       /* Translate connections from localhost to the real hostname */
> -     if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == 
> loopback_addr.s_addr)
> -        so->so_faddr = slirp->vhost_addr;
> +    if (so->so_faddr.s_addr == 0 ||
> +        (so->so_faddr.s_addr & loopback_mask) ==
> +        (loopback_addr.s_addr & loopback_mask)) {
> +        so->so_faddr = slirp->vhost_addr;
> +    }

Dropping tabs is desired, but as long as slirp is such a mess coding
style wise, I prefer keeping the indention depth consistent. I fixed
this up while merging it.

Out of curiosity: Which host platform requires this? Linux always
reports 127.0.0.1 as source, even when you bind the hostfwd rule to a
different localhost address.

Jan

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