Introduce IPv6-enabled version of get_client_address. The legacy mount
command could use this eventually as well.
If this new function fails to discover an appropriate callback address, it
fills in an ANY address to indicate to the server that it should not call the
client back (ie delegations are disabled in this case).
The user can specify a callback address via the clientaddr= mount option in
this case to enable delegation.
Signed-off-by: Chuck Lever <[email protected]>
---
utils/mount/network.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++
utils/mount/network.h | 2 +
2 files changed, 120 insertions(+), 0 deletions(-)
diff --git a/utils/mount/network.c b/utils/mount/network.c
index 3f2721b..849ce1d 100644
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -918,3 +918,121 @@ int get_client_address(struct sockaddr_in *saddr, struct sockaddr_in *caddr)
}
return 1;
}
+
+/*
+ * Try a getsockname() on a connected datagram socket.
+ *
+ * Returns 1 and fills in @buf if successful; otherwise, zero.
+ *
+ * A connected datagram socket prevents leaving a socket in TIME_WAIT.
+ * This conserves the ephemeral port number space, helping reduce failed
+ * socket binds during mount storms.
+ */
+static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen,
+ struct sockaddr *buf, socklen_t *buflen)
+{
+ struct sockaddr_in sin = {
+ .sin_family = AF_INET,
+ .sin_addr.s_addr = htonl(INADDR_ANY),
+ };
+ struct sockaddr_in6 sin6 = {
+ .sin6_family = AF_INET6,
+ .sin6_addr = IN6ADDR_ANY_INIT,
+ };
+ int sock;
+
+ sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
+ if (sock < 0)
+ return 0;
+
+ switch (sap->sa_family) {
+ case AF_INET:
+ if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
+ close(sock);
+ return 0;
+ }
+ break;
+ case AF_INET6:
+ if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
+ close(sock);
+ return 0;
+ }
+ break;
+ default:
+ errno = EAFNOSUPPORT;
+ return 0;
+ }
+
+ if (connect(sock, sap, salen) < 0) {
+ close(sock);
+ return 0;
+ }
+
+ return !getsockname(sock, buf, buflen);
+}
+
+/*
+ * Try to generate an address that prevents the server from calling us.
+ *
+ * Returns 1 and fills in @buf if successful; otherwise, zero.
+ */
+static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t salen,
+ struct sockaddr *buf, socklen_t *buflen)
+{
+ struct addrinfo *gai_results;
+ struct addrinfo gai_hint = {
+ .ai_family = sap->sa_family,
+ .ai_flags = AI_PASSIVE, /* ANYADDR */
+ };
+
+ if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
+ return 0;
+
+ *buflen = gai_results->ai_addrlen;
+ memcpy(buf, gai_results->ai_addr, *buflen);
+
+ freeaddrinfo(gai_results);
+
+ return 1;
+}
+
+/**
+ * nfs_callback_address - acquire our local network address
+ * @sap: pointer to address of remote
+ * @sap_len: length of address
+ * @buf: pointer to buffer to be filled in with local network address
+ * @buflen: IN: length of buffer to fill in; OUT: length of filled-in address
+ *
+ * Discover a network address that an NFSv4 server can use to call us back.
+ * On multi-homed clients, this address depends on which NIC we use to
+ * route requests to the server.
+ *
+ * Returns 1 and fills in @buf if an unambiguous local address is
+ * available; returns 1 and fills in an appropriate ANYADDR address
+ * if a local address isn't available; otherwise, returns zero.
+ */
+int nfs_callback_address(const struct sockaddr *sap, const socklen_t salen,
+ struct sockaddr *buf, socklen_t *buflen)
+{
+ struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
+
+ if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
+ if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
+ goto out_failed;
+
+ /*
+ * The server can't use an interface ID that was generated
+ * here on the client, so always clear sin6_scope_id.
+ */
+ if (sin6->sin6_family == AF_INET6)
+ sin6->sin6_scope_id = 0;
+
+ return 1;
+
+out_failed:
+ *buflen = 0;
+ if (verbose)
+ nfs_error(_("%s: failed to construct callback address"));
+ return 0;
+
+}
diff --git a/utils/mount/network.h b/utils/mount/network.h
index 8da7e20..2f4ff3a 100644
--- a/utils/mount/network.h
+++ b/utils/mount/network.h
@@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const size_t,
int nfs_present_sockaddr(const struct sockaddr *,
const socklen_t, char *, const size_t);
int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
+int nfs_callback_address(const struct sockaddr *, const socklen_t,
+ struct sockaddr *, socklen_t *);
int nfs_call_umount(clnt_addr_t *, dirpath *);
int clnt_ping(struct sockaddr_in *, const unsigned long,
const unsigned long, const unsigned int,
On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
> Introduce IPv6-enabled version of get_client_address. The legacy mount
> command could use this eventually as well.
>
> I don't remember how to tell an NFSv4 server to disable the callback
> channel: whether an ANY address is passed with SETCLIENTID, or a
> loopback address is passed. The patch allows either to be used with a
> compile-time switch.
I would have thought INADDR_ANY. But in any case we should just pick
one....
--b.
>
> Signed-off-by: Chuck Lever <[email protected]>
> ---
>
> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++++
> utils/mount/network.h | 2 +
> 2 files changed, 124 insertions(+), 0 deletions(-)
>
> diff --git a/utils/mount/network.c b/utils/mount/network.c
> index 3f2721b..128d7f7 100644
> --- a/utils/mount/network.c
> +++ b/utils/mount/network.c
> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in *saddr, struct sockaddr_in *caddr)
> }
> return 1;
> }
> +
> +/*
> + * Try a getsockname() on a connected datagram socket.
> + *
> + * Returns 1 and fills in @buf if successful; otherwise, zero.
> + *
> + * A connected datagram socket prevents leaving a socket in TIME_WAIT.
> + * This conserves the ephemeral port number space, helping reduce failed
> + * socket binds during mount storms.
> + */
> +static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen,
> + struct sockaddr *buf, socklen_t *buflen)
> +{
> + struct sockaddr_in sin = {
> + .sin_family = AF_INET,
> + .sin_addr.s_addr = htonl(INADDR_ANY),
> + };
> + struct sockaddr_in6 sin6 = {
> + .sin6_family = AF_INET6,
> + .sin6_addr = IN6ADDR_ANY_INIT,
> + };
> + int sock;
> +
> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
> + if (sock < 0)
> + return 0;
> +
> + switch (sap->sa_family) {
> + case AF_INET:
> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
> + close(sock);
> + return 0;
> + }
> + break;
> + case AF_INET6:
> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
> + close(sock);
> + return 0;
> + }
> + break;
> + default:
> + errno = EAFNOSUPPORT;
> + return 0;
> + }
> +
> + if (connect(sock, sap, salen) < 0) {
> + close(sock);
> + return 0;
> + }
> +
> + return !getsockname(sock, buf, buflen);
> +}
> +
> +/*
> + * Try to generate an address that prevents the server from calling us.
> + *
> + * Returns 1 and fills in @buf if successful; otherwise, zero.
> + */
> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t salen,
> + struct sockaddr *buf, socklen_t *buflen)
> +{
> + struct addrinfo *gai_results;
> + struct addrinfo gai_hint = {
> + .ai_family = sap->sa_family,
> +#ifdef GENERATE_LOOPBACK_ADDRESS
> + .ai_flags = 0, /* loopback */
> +#else
> + .ai_flags = AI_PASSIVE, /* ANYADDR */
> +#endif
> + };
> +
> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
> + return 0;
> +
> + *buflen = gai_results->ai_addrlen;
> + memcpy(buf, gai_results->ai_addr, *buflen);
> +
> + freeaddrinfo(gai_results);
> +
> + return 1;
> +}
> +
> +/**
> + * nfs_callback_address - acquire our local network address
> + * @sap: pointer to address of remote
> + * @sap_len: length of address
> + * @buf: pointer to buffer to be filled in with local network address
> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-in address
> + *
> + * Discover a network address that an NFSv4 server can use to call us back.
> + * On multi-homed clients, this address depends on which NIC we use to
> + * route requests to the server.
> + *
> + * Returns 1 and fills in @buf if an unambiguous local address is
> + * available; returns 1 and fills in an appropriate ANYADDR address
> + * if a local address isn't available; otherwise, returns zero.
> + */
> +int nfs_callback_address(const struct sockaddr *sap, const socklen_t salen,
> + struct sockaddr *buf, socklen_t *buflen)
> +{
> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
> +
> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
> + goto out_failed;
> +
> + /*
> + * The server can't use an interface ID that was generated
> + * here on the client, so always clear sin6_scope_id.
> + */
> + if (sin6->sin6_family == AF_INET6)
> + sin6->sin6_scope_id = 0;
> +
> + return 1;
> +
> +out_failed:
> + *buflen = 0;
> + if (verbose)
> + nfs_error(_("%s: failed to construct callback address"));
> + return 0;
> +
> +}
> diff --git a/utils/mount/network.h b/utils/mount/network.h
> index 8da7e20..2f4ff3a 100644
> --- a/utils/mount/network.h
> +++ b/utils/mount/network.h
> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const size_t,
> int nfs_present_sockaddr(const struct sockaddr *,
> const socklen_t, char *, const size_t);
> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
> + struct sockaddr *, socklen_t *);
> int nfs_call_umount(clnt_addr_t *, dirpath *);
> int clnt_ping(struct sockaddr_in *, const unsigned long,
> const unsigned long, const unsigned int,
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
On Jul 10, 2008, at 3:30 PM, J. Bruce Fields wrote:
> On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
>> Introduce IPv6-enabled version of get_client_address. The legacy
>> mount
>> command could use this eventually as well.
>>
>> I don't remember how to tell an NFSv4 server to disable the callback
>> channel: whether an ANY address is passed with SETCLIENTID, or a
>> loopback address is passed. The patch allows either to be used
>> with a
>> compile-time switch.
>
> I would have thought INADDR_ANY. But in any case we should just pick
> one....
Well, yes, but we should pick the "correct" one. :-) The patch does
it this way just to make a note of this issue so we can make a
decision before committing this upstream.
Does RFC 3530 have any recommendation about this?
>
>
> --b.
>
>>
>> Signed-off-by: Chuck Lever <[email protected]>
>> ---
>>
>> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++
>> ++++++++++
>> utils/mount/network.h | 2 +
>> 2 files changed, 124 insertions(+), 0 deletions(-)
>>
>> diff --git a/utils/mount/network.c b/utils/mount/network.c
>> index 3f2721b..128d7f7 100644
>> --- a/utils/mount/network.c
>> +++ b/utils/mount/network.c
>> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in
>> *saddr, struct sockaddr_in *caddr)
>> }
>> return 1;
>> }
>> +
>> +/*
>> + * Try a getsockname() on a connected datagram socket.
>> + *
>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>> + *
>> + * A connected datagram socket prevents leaving a socket in
>> TIME_WAIT.
>> + * This conserves the ephemeral port number space, helping reduce
>> failed
>> + * socket binds during mount storms.
>> + */
>> +static int nfs_ca_sockname(const struct sockaddr *sap, const
>> socklen_t salen,
>> + struct sockaddr *buf, socklen_t *buflen)
>> +{
>> + struct sockaddr_in sin = {
>> + .sin_family = AF_INET,
>> + .sin_addr.s_addr = htonl(INADDR_ANY),
>> + };
>> + struct sockaddr_in6 sin6 = {
>> + .sin6_family = AF_INET6,
>> + .sin6_addr = IN6ADDR_ANY_INIT,
>> + };
>> + int sock;
>> +
>> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
>> + if (sock < 0)
>> + return 0;
>> +
>> + switch (sap->sa_family) {
>> + case AF_INET:
>> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
>> + close(sock);
>> + return 0;
>> + }
>> + break;
>> + case AF_INET6:
>> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
>> + close(sock);
>> + return 0;
>> + }
>> + break;
>> + default:
>> + errno = EAFNOSUPPORT;
>> + return 0;
>> + }
>> +
>> + if (connect(sock, sap, salen) < 0) {
>> + close(sock);
>> + return 0;
>> + }
>> +
>> + return !getsockname(sock, buf, buflen);
>> +}
>> +
>> +/*
>> + * Try to generate an address that prevents the server from
>> calling us.
>> + *
>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>> + */
>> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t
>> salen,
>> + struct sockaddr *buf, socklen_t *buflen)
>> +{
>> + struct addrinfo *gai_results;
>> + struct addrinfo gai_hint = {
>> + .ai_family = sap->sa_family,
>> +#ifdef GENERATE_LOOPBACK_ADDRESS
>> + .ai_flags = 0, /* loopback */
>> +#else
>> + .ai_flags = AI_PASSIVE, /* ANYADDR */
>> +#endif
>> + };
>> +
>> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
>> + return 0;
>> +
>> + *buflen = gai_results->ai_addrlen;
>> + memcpy(buf, gai_results->ai_addr, *buflen);
>> +
>> + freeaddrinfo(gai_results);
>> +
>> + return 1;
>> +}
>> +
>> +/**
>> + * nfs_callback_address - acquire our local network address
>> + * @sap: pointer to address of remote
>> + * @sap_len: length of address
>> + * @buf: pointer to buffer to be filled in with local network
>> address
>> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-
>> in address
>> + *
>> + * Discover a network address that an NFSv4 server can use to call
>> us back.
>> + * On multi-homed clients, this address depends on which NIC we
>> use to
>> + * route requests to the server.
>> + *
>> + * Returns 1 and fills in @buf if an unambiguous local address is
>> + * available; returns 1 and fills in an appropriate ANYADDR address
>> + * if a local address isn't available; otherwise, returns zero.
>> + */
>> +int nfs_callback_address(const struct sockaddr *sap, const
>> socklen_t salen,
>> + struct sockaddr *buf, socklen_t *buflen)
>> +{
>> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
>> +
>> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
>> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
>> + goto out_failed;
>> +
>> + /*
>> + * The server can't use an interface ID that was generated
>> + * here on the client, so always clear sin6_scope_id.
>> + */
>> + if (sin6->sin6_family == AF_INET6)
>> + sin6->sin6_scope_id = 0;
>> +
>> + return 1;
>> +
>> +out_failed:
>> + *buflen = 0;
>> + if (verbose)
>> + nfs_error(_("%s: failed to construct callback address"));
>> + return 0;
>> +
>> +}
>> diff --git a/utils/mount/network.h b/utils/mount/network.h
>> index 8da7e20..2f4ff3a 100644
>> --- a/utils/mount/network.h
>> +++ b/utils/mount/network.h
>> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const
>> size_t,
>> int nfs_present_sockaddr(const struct sockaddr *,
>> const socklen_t, char *, const size_t);
>> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
>> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
>> + struct sockaddr *, socklen_t *);
>> int nfs_call_umount(clnt_addr_t *, dirpath *);
>> int clnt_ping(struct sockaddr_in *, const unsigned long,
>> const unsigned long, const unsigned int,
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-
>> nfs" in
>> the body of a message to [email protected]
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
On Thu, Jul 10, 2008 at 03:36:21PM -0400, Chuck Lever wrote:
> On Jul 10, 2008, at 3:30 PM, J. Bruce Fields wrote:
>> On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
>>> Introduce IPv6-enabled version of get_client_address. The legacy
>>> mount
>>> command could use this eventually as well.
>>>
>>> I don't remember how to tell an NFSv4 server to disable the callback
>>> channel: whether an ANY address is passed with SETCLIENTID, or a
>>> loopback address is passed. The patch allows either to be used with
>>> a
>>> compile-time switch.
>>
>> I would have thought INADDR_ANY. But in any case we should just pick
>> one....
>
> Well, yes, but we should pick the "correct" one. :-) The patch does it
> this way just to make a note of this issue so we can make a decision
> before committing this upstream.
>
> Does RFC 3530 have any recommendation about this?
Not that I can find on a quick skim.
I don't see why the spec would forbid running over loopback, though, in
which case a loopback callback address would make sense. And I assume
INADDR_ANY is always meaningless as a destination address, so is a
logical way to tell the server it can't call back to you.
--b.
>
>>
>>
>> --b.
>>
>>>
>>> Signed-off-by: Chuck Lever <[email protected]>
>>> ---
>>>
>>> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++
>>> ++++++++++
>>> utils/mount/network.h | 2 +
>>> 2 files changed, 124 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/utils/mount/network.c b/utils/mount/network.c
>>> index 3f2721b..128d7f7 100644
>>> --- a/utils/mount/network.c
>>> +++ b/utils/mount/network.c
>>> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in
>>> *saddr, struct sockaddr_in *caddr)
>>> }
>>> return 1;
>>> }
>>> +
>>> +/*
>>> + * Try a getsockname() on a connected datagram socket.
>>> + *
>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>>> + *
>>> + * A connected datagram socket prevents leaving a socket in
>>> TIME_WAIT.
>>> + * This conserves the ephemeral port number space, helping reduce
>>> failed
>>> + * socket binds during mount storms.
>>> + */
>>> +static int nfs_ca_sockname(const struct sockaddr *sap, const
>>> socklen_t salen,
>>> + struct sockaddr *buf, socklen_t *buflen)
>>> +{
>>> + struct sockaddr_in sin = {
>>> + .sin_family = AF_INET,
>>> + .sin_addr.s_addr = htonl(INADDR_ANY),
>>> + };
>>> + struct sockaddr_in6 sin6 = {
>>> + .sin6_family = AF_INET6,
>>> + .sin6_addr = IN6ADDR_ANY_INIT,
>>> + };
>>> + int sock;
>>> +
>>> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
>>> + if (sock < 0)
>>> + return 0;
>>> +
>>> + switch (sap->sa_family) {
>>> + case AF_INET:
>>> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
>>> + close(sock);
>>> + return 0;
>>> + }
>>> + break;
>>> + case AF_INET6:
>>> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
>>> + close(sock);
>>> + return 0;
>>> + }
>>> + break;
>>> + default:
>>> + errno = EAFNOSUPPORT;
>>> + return 0;
>>> + }
>>> +
>>> + if (connect(sock, sap, salen) < 0) {
>>> + close(sock);
>>> + return 0;
>>> + }
>>> +
>>> + return !getsockname(sock, buf, buflen);
>>> +}
>>> +
>>> +/*
>>> + * Try to generate an address that prevents the server from calling
>>> us.
>>> + *
>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>>> + */
>>> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t
>>> salen,
>>> + struct sockaddr *buf, socklen_t *buflen)
>>> +{
>>> + struct addrinfo *gai_results;
>>> + struct addrinfo gai_hint = {
>>> + .ai_family = sap->sa_family,
>>> +#ifdef GENERATE_LOOPBACK_ADDRESS
>>> + .ai_flags = 0, /* loopback */
>>> +#else
>>> + .ai_flags = AI_PASSIVE, /* ANYADDR */
>>> +#endif
>>> + };
>>> +
>>> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
>>> + return 0;
>>> +
>>> + *buflen = gai_results->ai_addrlen;
>>> + memcpy(buf, gai_results->ai_addr, *buflen);
>>> +
>>> + freeaddrinfo(gai_results);
>>> +
>>> + return 1;
>>> +}
>>> +
>>> +/**
>>> + * nfs_callback_address - acquire our local network address
>>> + * @sap: pointer to address of remote
>>> + * @sap_len: length of address
>>> + * @buf: pointer to buffer to be filled in with local network
>>> address
>>> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-
>>> in address
>>> + *
>>> + * Discover a network address that an NFSv4 server can use to call
>>> us back.
>>> + * On multi-homed clients, this address depends on which NIC we use
>>> to
>>> + * route requests to the server.
>>> + *
>>> + * Returns 1 and fills in @buf if an unambiguous local address is
>>> + * available; returns 1 and fills in an appropriate ANYADDR address
>>> + * if a local address isn't available; otherwise, returns zero.
>>> + */
>>> +int nfs_callback_address(const struct sockaddr *sap, const
>>> socklen_t salen,
>>> + struct sockaddr *buf, socklen_t *buflen)
>>> +{
>>> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
>>> +
>>> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
>>> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
>>> + goto out_failed;
>>> +
>>> + /*
>>> + * The server can't use an interface ID that was generated
>>> + * here on the client, so always clear sin6_scope_id.
>>> + */
>>> + if (sin6->sin6_family == AF_INET6)
>>> + sin6->sin6_scope_id = 0;
>>> +
>>> + return 1;
>>> +
>>> +out_failed:
>>> + *buflen = 0;
>>> + if (verbose)
>>> + nfs_error(_("%s: failed to construct callback address"));
>>> + return 0;
>>> +
>>> +}
>>> diff --git a/utils/mount/network.h b/utils/mount/network.h
>>> index 8da7e20..2f4ff3a 100644
>>> --- a/utils/mount/network.h
>>> +++ b/utils/mount/network.h
>>> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const
>>> size_t,
>>> int nfs_present_sockaddr(const struct sockaddr *,
>>> const socklen_t, char *, const size_t);
>>> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
>>> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
>>> + struct sockaddr *, socklen_t *);
>>> int nfs_call_umount(clnt_addr_t *, dirpath *);
>>> int clnt_ping(struct sockaddr_in *, const unsigned long,
>>> const unsigned long, const unsigned int,
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs"
>>> in
>>> the body of a message to [email protected]
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>
On Thu, Jul 10, 2008 at 3:43 PM, J. Bruce Fields <[email protected]> wrote:
> On Thu, Jul 10, 2008 at 03:36:21PM -0400, Chuck Lever wrote:
>> On Jul 10, 2008, at 3:30 PM, J. Bruce Fields wrote:
>>> On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
>>>> Introduce IPv6-enabled version of get_client_address. The legacy
>>>> mount
>>>> command could use this eventually as well.
>>>>
>>>> I don't remember how to tell an NFSv4 server to disable the callback
>>>> channel: whether an ANY address is passed with SETCLIENTID, or a
>>>> loopback address is passed. The patch allows either to be used with
>>>> a
>>>> compile-time switch.
>>>
>>> I would have thought INADDR_ANY. But in any case we should just pick
>>> one....
>>
>> Well, yes, but we should pick the "correct" one. :-) The patch does it
>> this way just to make a note of this issue so we can make a decision
>> before committing this upstream.
>>
>> Does RFC 3530 have any recommendation about this?
>
> Not that I can find on a quick skim.
Is it clarified in the NFSv4.1 draft?
> I don't see why the spec would forbid running over loopback, though, in
> which case a loopback callback address would make sense. And I assume
> INADDR_ANY is always meaningless as a destination address, so is a
> logical way to tell the server it can't call back to you.
Yep, I agree.
I recall a few years back at a CITI bake-a-thon there was a certain
server vendor who had trouble with loopback callback addresses,
probably because their implementation was server-only, so an NFSv4
callback from loopback would make no sense for them. The client in
this case was sending a loopback callback address because it hadn't
implemented a callback service and wanted to prevent the server from
calling it back.
Do we have a high degree of certainty that sending an ANY address is
appropriate if the client can't determine a reasonable callback
address to send with SETCLIENTID?
Is it at least OK for Linux's NFSv4 server?
If we think this might be a problem, I can change all this back to
simply failing the mount request when the mount.nfs command can't
figure out a valid callback address.
>>>>
>>>> Signed-off-by: Chuck Lever <[email protected]>
>>>> ---
>>>>
>>>> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++
>>>> ++++++++++
>>>> utils/mount/network.h | 2 +
>>>> 2 files changed, 124 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/utils/mount/network.c b/utils/mount/network.c
>>>> index 3f2721b..128d7f7 100644
>>>> --- a/utils/mount/network.c
>>>> +++ b/utils/mount/network.c
>>>> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in
>>>> *saddr, struct sockaddr_in *caddr)
>>>> }
>>>> return 1;
>>>> }
>>>> +
>>>> +/*
>>>> + * Try a getsockname() on a connected datagram socket.
>>>> + *
>>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>>>> + *
>>>> + * A connected datagram socket prevents leaving a socket in
>>>> TIME_WAIT.
>>>> + * This conserves the ephemeral port number space, helping reduce
>>>> failed
>>>> + * socket binds during mount storms.
>>>> + */
>>>> +static int nfs_ca_sockname(const struct sockaddr *sap, const
>>>> socklen_t salen,
>>>> + struct sockaddr *buf, socklen_t *buflen)
>>>> +{
>>>> + struct sockaddr_in sin = {
>>>> + .sin_family = AF_INET,
>>>> + .sin_addr.s_addr = htonl(INADDR_ANY),
>>>> + };
>>>> + struct sockaddr_in6 sin6 = {
>>>> + .sin6_family = AF_INET6,
>>>> + .sin6_addr = IN6ADDR_ANY_INIT,
>>>> + };
>>>> + int sock;
>>>> +
>>>> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
>>>> + if (sock < 0)
>>>> + return 0;
>>>> +
>>>> + switch (sap->sa_family) {
>>>> + case AF_INET:
>>>> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
>>>> + close(sock);
>>>> + return 0;
>>>> + }
>>>> + break;
>>>> + case AF_INET6:
>>>> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
>>>> + close(sock);
>>>> + return 0;
>>>> + }
>>>> + break;
>>>> + default:
>>>> + errno = EAFNOSUPPORT;
>>>> + return 0;
>>>> + }
>>>> +
>>>> + if (connect(sock, sap, salen) < 0) {
>>>> + close(sock);
>>>> + return 0;
>>>> + }
>>>> +
>>>> + return !getsockname(sock, buf, buflen);
>>>> +}
>>>> +
>>>> +/*
>>>> + * Try to generate an address that prevents the server from calling
>>>> us.
>>>> + *
>>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>>>> + */
>>>> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t
>>>> salen,
>>>> + struct sockaddr *buf, socklen_t *buflen)
>>>> +{
>>>> + struct addrinfo *gai_results;
>>>> + struct addrinfo gai_hint = {
>>>> + .ai_family = sap->sa_family,
>>>> +#ifdef GENERATE_LOOPBACK_ADDRESS
>>>> + .ai_flags = 0, /* loopback */
>>>> +#else
>>>> + .ai_flags = AI_PASSIVE, /* ANYADDR */
>>>> +#endif
>>>> + };
>>>> +
>>>> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
>>>> + return 0;
>>>> +
>>>> + *buflen = gai_results->ai_addrlen;
>>>> + memcpy(buf, gai_results->ai_addr, *buflen);
>>>> +
>>>> + freeaddrinfo(gai_results);
>>>> +
>>>> + return 1;
>>>> +}
>>>> +
>>>> +/**
>>>> + * nfs_callback_address - acquire our local network address
>>>> + * @sap: pointer to address of remote
>>>> + * @sap_len: length of address
>>>> + * @buf: pointer to buffer to be filled in with local network
>>>> address
>>>> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-
>>>> in address
>>>> + *
>>>> + * Discover a network address that an NFSv4 server can use to call
>>>> us back.
>>>> + * On multi-homed clients, this address depends on which NIC we use
>>>> to
>>>> + * route requests to the server.
>>>> + *
>>>> + * Returns 1 and fills in @buf if an unambiguous local address is
>>>> + * available; returns 1 and fills in an appropriate ANYADDR address
>>>> + * if a local address isn't available; otherwise, returns zero.
>>>> + */
>>>> +int nfs_callback_address(const struct sockaddr *sap, const
>>>> socklen_t salen,
>>>> + struct sockaddr *buf, socklen_t *buflen)
>>>> +{
>>>> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
>>>> +
>>>> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
>>>> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
>>>> + goto out_failed;
>>>> +
>>>> + /*
>>>> + * The server can't use an interface ID that was generated
>>>> + * here on the client, so always clear sin6_scope_id.
>>>> + */
>>>> + if (sin6->sin6_family == AF_INET6)
>>>> + sin6->sin6_scope_id = 0;
>>>> +
>>>> + return 1;
>>>> +
>>>> +out_failed:
>>>> + *buflen = 0;
>>>> + if (verbose)
>>>> + nfs_error(_("%s: failed to construct callback address"));
>>>> + return 0;
>>>> +
>>>> +}
>>>> diff --git a/utils/mount/network.h b/utils/mount/network.h
>>>> index 8da7e20..2f4ff3a 100644
>>>> --- a/utils/mount/network.h
>>>> +++ b/utils/mount/network.h
>>>> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const
>>>> size_t,
>>>> int nfs_present_sockaddr(const struct sockaddr *,
>>>> const socklen_t, char *, const size_t);
>>>> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
>>>> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
>>>> + struct sockaddr *, socklen_t *);
>>>> int nfs_call_umount(clnt_addr_t *, dirpath *);
>>>> int clnt_ping(struct sockaddr_in *, const unsigned long,
>>>> const unsigned long, const unsigned int,
>>>>
--
Chuck Lever
On Thu, Jul 10, 2008 at 04:35:57PM -0400, Chuck Lever wrote:
> On Thu, Jul 10, 2008 at 3:43 PM, J. Bruce Fields <[email protected]> wrote:
> > On Thu, Jul 10, 2008 at 03:36:21PM -0400, Chuck Lever wrote:
> >> On Jul 10, 2008, at 3:30 PM, J. Bruce Fields wrote:
> >>> On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
> >>>> Introduce IPv6-enabled version of get_client_address. The legacy
> >>>> mount
> >>>> command could use this eventually as well.
> >>>>
> >>>> I don't remember how to tell an NFSv4 server to disable the callback
> >>>> channel: whether an ANY address is passed with SETCLIENTID, or a
> >>>> loopback address is passed. The patch allows either to be used with
> >>>> a
> >>>> compile-time switch.
> >>>
> >>> I would have thought INADDR_ANY. But in any case we should just pick
> >>> one....
> >>
> >> Well, yes, but we should pick the "correct" one. :-) The patch does it
> >> this way just to make a note of this issue so we can make a decision
> >> before committing this upstream.
> >>
> >> Does RFC 3530 have any recommendation about this?
> >
> > Not that I can find on a quick skim.
>
> Is it clarified in the NFSv4.1 draft?
4.1 callbacks use sessions, which I don't really know yet.
> > I don't see why the spec would forbid running over loopback, though, in
> > which case a loopback callback address would make sense. And I assume
> > INADDR_ANY is always meaningless as a destination address, so is a
> > logical way to tell the server it can't call back to you.
>
> Yep, I agree.
>
> I recall a few years back at a CITI bake-a-thon there was a certain
> server vendor who had trouble with loopback callback addresses,
> probably because their implementation was server-only, so an NFSv4
> callback from loopback would make no sense for them. The client in
> this case was sending a loopback callback address because it hadn't
> implemented a callback service and wanted to prevent the server from
> calling it back.
>
> Do we have a high degree of certainty that sending an ANY address is
> appropriate if the client can't determine a reasonable callback
> address to send with SETCLIENTID?
>
> Is it at least OK for Linux's NFSv4 server?
If not, it's a bug I'd want to fix.
--b.
>
> If we think this might be a problem, I can change all this back to
> simply failing the mount request when the mount.nfs command can't
> figure out a valid callback address.
>
> >>>>
> >>>> Signed-off-by: Chuck Lever <[email protected]>
> >>>> ---
> >>>>
> >>>> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++
> >>>> ++++++++++
> >>>> utils/mount/network.h | 2 +
> >>>> 2 files changed, 124 insertions(+), 0 deletions(-)
> >>>>
> >>>> diff --git a/utils/mount/network.c b/utils/mount/network.c
> >>>> index 3f2721b..128d7f7 100644
> >>>> --- a/utils/mount/network.c
> >>>> +++ b/utils/mount/network.c
> >>>> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in
> >>>> *saddr, struct sockaddr_in *caddr)
> >>>> }
> >>>> return 1;
> >>>> }
> >>>> +
> >>>> +/*
> >>>> + * Try a getsockname() on a connected datagram socket.
> >>>> + *
> >>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
> >>>> + *
> >>>> + * A connected datagram socket prevents leaving a socket in
> >>>> TIME_WAIT.
> >>>> + * This conserves the ephemeral port number space, helping reduce
> >>>> failed
> >>>> + * socket binds during mount storms.
> >>>> + */
> >>>> +static int nfs_ca_sockname(const struct sockaddr *sap, const
> >>>> socklen_t salen,
> >>>> + struct sockaddr *buf, socklen_t *buflen)
> >>>> +{
> >>>> + struct sockaddr_in sin = {
> >>>> + .sin_family = AF_INET,
> >>>> + .sin_addr.s_addr = htonl(INADDR_ANY),
> >>>> + };
> >>>> + struct sockaddr_in6 sin6 = {
> >>>> + .sin6_family = AF_INET6,
> >>>> + .sin6_addr = IN6ADDR_ANY_INIT,
> >>>> + };
> >>>> + int sock;
> >>>> +
> >>>> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
> >>>> + if (sock < 0)
> >>>> + return 0;
> >>>> +
> >>>> + switch (sap->sa_family) {
> >>>> + case AF_INET:
> >>>> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
> >>>> + close(sock);
> >>>> + return 0;
> >>>> + }
> >>>> + break;
> >>>> + case AF_INET6:
> >>>> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
> >>>> + close(sock);
> >>>> + return 0;
> >>>> + }
> >>>> + break;
> >>>> + default:
> >>>> + errno = EAFNOSUPPORT;
> >>>> + return 0;
> >>>> + }
> >>>> +
> >>>> + if (connect(sock, sap, salen) < 0) {
> >>>> + close(sock);
> >>>> + return 0;
> >>>> + }
> >>>> +
> >>>> + return !getsockname(sock, buf, buflen);
> >>>> +}
> >>>> +
> >>>> +/*
> >>>> + * Try to generate an address that prevents the server from calling
> >>>> us.
> >>>> + *
> >>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
> >>>> + */
> >>>> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t
> >>>> salen,
> >>>> + struct sockaddr *buf, socklen_t *buflen)
> >>>> +{
> >>>> + struct addrinfo *gai_results;
> >>>> + struct addrinfo gai_hint = {
> >>>> + .ai_family = sap->sa_family,
> >>>> +#ifdef GENERATE_LOOPBACK_ADDRESS
> >>>> + .ai_flags = 0, /* loopback */
> >>>> +#else
> >>>> + .ai_flags = AI_PASSIVE, /* ANYADDR */
> >>>> +#endif
> >>>> + };
> >>>> +
> >>>> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
> >>>> + return 0;
> >>>> +
> >>>> + *buflen = gai_results->ai_addrlen;
> >>>> + memcpy(buf, gai_results->ai_addr, *buflen);
> >>>> +
> >>>> + freeaddrinfo(gai_results);
> >>>> +
> >>>> + return 1;
> >>>> +}
> >>>> +
> >>>> +/**
> >>>> + * nfs_callback_address - acquire our local network address
> >>>> + * @sap: pointer to address of remote
> >>>> + * @sap_len: length of address
> >>>> + * @buf: pointer to buffer to be filled in with local network
> >>>> address
> >>>> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-
> >>>> in address
> >>>> + *
> >>>> + * Discover a network address that an NFSv4 server can use to call
> >>>> us back.
> >>>> + * On multi-homed clients, this address depends on which NIC we use
> >>>> to
> >>>> + * route requests to the server.
> >>>> + *
> >>>> + * Returns 1 and fills in @buf if an unambiguous local address is
> >>>> + * available; returns 1 and fills in an appropriate ANYADDR address
> >>>> + * if a local address isn't available; otherwise, returns zero.
> >>>> + */
> >>>> +int nfs_callback_address(const struct sockaddr *sap, const
> >>>> socklen_t salen,
> >>>> + struct sockaddr *buf, socklen_t *buflen)
> >>>> +{
> >>>> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
> >>>> +
> >>>> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
> >>>> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
> >>>> + goto out_failed;
> >>>> +
> >>>> + /*
> >>>> + * The server can't use an interface ID that was generated
> >>>> + * here on the client, so always clear sin6_scope_id.
> >>>> + */
> >>>> + if (sin6->sin6_family == AF_INET6)
> >>>> + sin6->sin6_scope_id = 0;
> >>>> +
> >>>> + return 1;
> >>>> +
> >>>> +out_failed:
> >>>> + *buflen = 0;
> >>>> + if (verbose)
> >>>> + nfs_error(_("%s: failed to construct callback address"));
> >>>> + return 0;
> >>>> +
> >>>> +}
> >>>> diff --git a/utils/mount/network.h b/utils/mount/network.h
> >>>> index 8da7e20..2f4ff3a 100644
> >>>> --- a/utils/mount/network.h
> >>>> +++ b/utils/mount/network.h
> >>>> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const
> >>>> size_t,
> >>>> int nfs_present_sockaddr(const struct sockaddr *,
> >>>> const socklen_t, char *, const size_t);
> >>>> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
> >>>> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
> >>>> + struct sockaddr *, socklen_t *);
> >>>> int nfs_call_umount(clnt_addr_t *, dirpath *);
> >>>> int clnt_ping(struct sockaddr_in *, const unsigned long,
> >>>> const unsigned long, const unsigned int,
> >>>>
>
>
>
> --
> Chuck Lever
On Fri, Jul 11, 2008 at 3:06 PM, J. Bruce Fields <[email protected]> wrote:
> On Thu, Jul 10, 2008 at 04:35:57PM -0400, Chuck Lever wrote:
>> On Thu, Jul 10, 2008 at 3:43 PM, J. Bruce Fields <[email protected]> wrote:
>> > On Thu, Jul 10, 2008 at 03:36:21PM -0400, Chuck Lever wrote:
>> >> On Jul 10, 2008, at 3:30 PM, J. Bruce Fields wrote:
>> >>> On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote:
>> >>>> Introduce IPv6-enabled version of get_client_address. The legacy
>> >>>> mount
>> >>>> command could use this eventually as well.
>> >>>>
>> >>>> I don't remember how to tell an NFSv4 server to disable the callback
>> >>>> channel: whether an ANY address is passed with SETCLIENTID, or a
>> >>>> loopback address is passed. The patch allows either to be used with
>> >>>> a
>> >>>> compile-time switch.
>> >>>
>> >>> I would have thought INADDR_ANY. But in any case we should just pick
>> >>> one....
>> >>
>> >> Well, yes, but we should pick the "correct" one. :-) The patch does it
>> >> this way just to make a note of this issue so we can make a decision
>> >> before committing this upstream.
>> >>
>> >> Does RFC 3530 have any recommendation about this?
>> >
>> > Not that I can find on a quick skim.
>>
>> Is it clarified in the NFSv4.1 draft?
>
> 4.1 callbacks use sessions, which I don't really know yet.
OK, but I thought the draft also contained some clarifications for
4.0, which is why I asked. Maybe I'm thinking of something else.
>> > I don't see why the spec would forbid running over loopback, though, in
>> > which case a loopback callback address would make sense. And I assume
>> > INADDR_ANY is always meaningless as a destination address, so is a
>> > logical way to tell the server it can't call back to you.
>>
>> Yep, I agree.
>>
>> I recall a few years back at a CITI bake-a-thon there was a certain
>> server vendor who had trouble with loopback callback addresses,
>> probably because their implementation was server-only, so an NFSv4
>> callback from loopback would make no sense for them. The client in
>> this case was sending a loopback callback address because it hadn't
>> implemented a callback service and wanted to prevent the server from
>> calling it back.
>>
>> Do we have a high degree of certainty that sending an ANY address is
>> appropriate if the client can't determine a reasonable callback
>> address to send with SETCLIENTID?
>>
>> Is it at least OK for Linux's NFSv4 server?
>
> If not, it's a bug I'd want to fix.
So to sum up, you think it is reasonable for the mount.nfs command to
specify clientaddr=0.0.0.0 if it can't determine the client's own
address for the server to use for callback.
I can clean that up in these patches and repost. Thanks for the review.
>> If we think this might be a problem, I can change all this back to
>> simply failing the mount request when the mount.nfs command can't
>> figure out a valid callback address.
>>
>> >>>>
>> >>>> Signed-off-by: Chuck Lever <[email protected]>
>> >>>> ---
>> >>>>
>> >>>> utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++
>> >>>> ++++++++++
>> >>>> utils/mount/network.h | 2 +
>> >>>> 2 files changed, 124 insertions(+), 0 deletions(-)
>> >>>>
>> >>>> diff --git a/utils/mount/network.c b/utils/mount/network.c
>> >>>> index 3f2721b..128d7f7 100644
>> >>>> --- a/utils/mount/network.c
>> >>>> +++ b/utils/mount/network.c
>> >>>> @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in
>> >>>> *saddr, struct sockaddr_in *caddr)
>> >>>> }
>> >>>> return 1;
>> >>>> }
>> >>>> +
>> >>>> +/*
>> >>>> + * Try a getsockname() on a connected datagram socket.
>> >>>> + *
>> >>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>> >>>> + *
>> >>>> + * A connected datagram socket prevents leaving a socket in
>> >>>> TIME_WAIT.
>> >>>> + * This conserves the ephemeral port number space, helping reduce
>> >>>> failed
>> >>>> + * socket binds during mount storms.
>> >>>> + */
>> >>>> +static int nfs_ca_sockname(const struct sockaddr *sap, const
>> >>>> socklen_t salen,
>> >>>> + struct sockaddr *buf, socklen_t *buflen)
>> >>>> +{
>> >>>> + struct sockaddr_in sin = {
>> >>>> + .sin_family = AF_INET,
>> >>>> + .sin_addr.s_addr = htonl(INADDR_ANY),
>> >>>> + };
>> >>>> + struct sockaddr_in6 sin6 = {
>> >>>> + .sin6_family = AF_INET6,
>> >>>> + .sin6_addr = IN6ADDR_ANY_INIT,
>> >>>> + };
>> >>>> + int sock;
>> >>>> +
>> >>>> + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
>> >>>> + if (sock < 0)
>> >>>> + return 0;
>> >>>> +
>> >>>> + switch (sap->sa_family) {
>> >>>> + case AF_INET:
>> >>>> + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
>> >>>> + close(sock);
>> >>>> + return 0;
>> >>>> + }
>> >>>> + break;
>> >>>> + case AF_INET6:
>> >>>> + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) {
>> >>>> + close(sock);
>> >>>> + return 0;
>> >>>> + }
>> >>>> + break;
>> >>>> + default:
>> >>>> + errno = EAFNOSUPPORT;
>> >>>> + return 0;
>> >>>> + }
>> >>>> +
>> >>>> + if (connect(sock, sap, salen) < 0) {
>> >>>> + close(sock);
>> >>>> + return 0;
>> >>>> + }
>> >>>> +
>> >>>> + return !getsockname(sock, buf, buflen);
>> >>>> +}
>> >>>> +
>> >>>> +/*
>> >>>> + * Try to generate an address that prevents the server from calling
>> >>>> us.
>> >>>> + *
>> >>>> + * Returns 1 and fills in @buf if successful; otherwise, zero.
>> >>>> + */
>> >>>> +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t
>> >>>> salen,
>> >>>> + struct sockaddr *buf, socklen_t *buflen)
>> >>>> +{
>> >>>> + struct addrinfo *gai_results;
>> >>>> + struct addrinfo gai_hint = {
>> >>>> + .ai_family = sap->sa_family,
>> >>>> +#ifdef GENERATE_LOOPBACK_ADDRESS
>> >>>> + .ai_flags = 0, /* loopback */
>> >>>> +#else
>> >>>> + .ai_flags = AI_PASSIVE, /* ANYADDR */
>> >>>> +#endif
>> >>>> + };
>> >>>> +
>> >>>> + if (getaddrinfo(NULL, "", &gai_hint, &gai_results))
>> >>>> + return 0;
>> >>>> +
>> >>>> + *buflen = gai_results->ai_addrlen;
>> >>>> + memcpy(buf, gai_results->ai_addr, *buflen);
>> >>>> +
>> >>>> + freeaddrinfo(gai_results);
>> >>>> +
>> >>>> + return 1;
>> >>>> +}
>> >>>> +
>> >>>> +/**
>> >>>> + * nfs_callback_address - acquire our local network address
>> >>>> + * @sap: pointer to address of remote
>> >>>> + * @sap_len: length of address
>> >>>> + * @buf: pointer to buffer to be filled in with local network
>> >>>> address
>> >>>> + * @buflen: IN: length of buffer to fill in; OUT: length of filled-
>> >>>> in address
>> >>>> + *
>> >>>> + * Discover a network address that an NFSv4 server can use to call
>> >>>> us back.
>> >>>> + * On multi-homed clients, this address depends on which NIC we use
>> >>>> to
>> >>>> + * route requests to the server.
>> >>>> + *
>> >>>> + * Returns 1 and fills in @buf if an unambiguous local address is
>> >>>> + * available; returns 1 and fills in an appropriate ANYADDR address
>> >>>> + * if a local address isn't available; otherwise, returns zero.
>> >>>> + */
>> >>>> +int nfs_callback_address(const struct sockaddr *sap, const
>> >>>> socklen_t salen,
>> >>>> + struct sockaddr *buf, socklen_t *buflen)
>> >>>> +{
>> >>>> + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
>> >>>> +
>> >>>> + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0)
>> >>>> + if (nfs_ca_gai(sap, salen, buf, buflen) == 0)
>> >>>> + goto out_failed;
>> >>>> +
>> >>>> + /*
>> >>>> + * The server can't use an interface ID that was generated
>> >>>> + * here on the client, so always clear sin6_scope_id.
>> >>>> + */
>> >>>> + if (sin6->sin6_family == AF_INET6)
>> >>>> + sin6->sin6_scope_id = 0;
>> >>>> +
>> >>>> + return 1;
>> >>>> +
>> >>>> +out_failed:
>> >>>> + *buflen = 0;
>> >>>> + if (verbose)
>> >>>> + nfs_error(_("%s: failed to construct callback address"));
>> >>>> + return 0;
>> >>>> +
>> >>>> +}
>> >>>> diff --git a/utils/mount/network.h b/utils/mount/network.h
>> >>>> index 8da7e20..2f4ff3a 100644
>> >>>> --- a/utils/mount/network.h
>> >>>> +++ b/utils/mount/network.h
>> >>>> @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const
>> >>>> size_t,
>> >>>> int nfs_present_sockaddr(const struct sockaddr *,
>> >>>> const socklen_t, char *, const size_t);
>> >>>> int get_client_address(struct sockaddr_in *, struct sockaddr_in *);
>> >>>> +int nfs_callback_address(const struct sockaddr *, const socklen_t,
>> >>>> + struct sockaddr *, socklen_t *);
>> >>>> int nfs_call_umount(clnt_addr_t *, dirpath *);
>> >>>> int clnt_ping(struct sockaddr_in *, const unsigned long,
>> >>>> const unsigned long, const unsigned int,
>> >>>>
>>
>>
>>
>> --
>> Chuck Lever
>
--
Edward R. Murrow told his generation of journalists no one can
eliminate their prejudices, just recognize them. Here is my bias:
extremes of wealth and poverty cannot be reconciled with a truly just
society.
-- Bill Moyers