On Mon, Jul 03, 2017 at 10:43:13AM -0400, Neil Horman wrote:
> With the addition of the SCTP_SOCKOPT_PEELOFF_FLAGS socket option for
> linux, this patch adds a library function to support its use. For non
> linux systems, when the call is used with a 0 flag set, the behavior
> will be identical to sctp_peeloff, and with a non-zero flag set for
> non-linux operating systems, a runtime error will be returned.
>
> Signed-off-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> CC: Vlad Yasevich <vyasevic@xxxxxxxxxx>
> CC: Daniel Borkmann <dborkman@xxxxxxxxxx>
> ---
> man/sctp_peeloff.3 | 16 ++++++++++++++++
> src/include/netinet/sctp.h | 6 ++++++
> src/lib/peeloff.c | 42 ++++++++++++++++++++++++++++--------------
> 3 files changed, 50 insertions(+), 14 deletions(-)
>
> diff --git a/man/sctp_peeloff.3 b/man/sctp_peeloff.3
> index 7cbde5d..e136ece 100644
> --- a/man/sctp_peeloff.3
> +++ b/man/sctp_peeloff.3
> @@ -15,6 +15,7 @@ sctp_peeloff \- Branch off an association into a separate socket.
> .B #include <netinet/sctp.h>
> .sp
> .BI "int sctp_peeloff(int " sd ", sctp_assoc_t " assoc_id );
> +.BI "int sctp_peeloff_flags(int " sd ", sctp_assoc_t " assoc_id ", unsigned " flags);
Please add a space between 'flags' and ), otherwise man will underline
the ');' too.
> .fi
> .SH DESCRIPTION
> .B sctp_peeloff
> @@ -28,6 +29,18 @@ This is particularly desirable when, for instance, the application wishes to
> have a number of sporadic message senders/receivers remain under the original
> one-to-many style socket, but branch off those assocations carrying high volume
> data traffic into their own separate socket descriptors.
> +
> +.B sctp_peeloff_flags
> +Is a variant of sctp_peeloff_flags, in which flags describing the behavior of
To follow the standard on the paragraph above, 'is' without capital
looks nicer.
> +the newly peeled off socket can be specified. Currently the supported flags
> +are:
> +.PP
Why PP? sctp_sendmsg is using TP instead, putting the description on a
line below the flag.
> +.B SOCK_NONBLOCK
> +Specifies that the new socket should not block on io operations
Missing final dot on this line.
> +.PP
> +.B SOCK_CLOEXEC
> +Specifies that the new socket should be closed when the owning process calls
> +exec.
> .SH "RETURN VALUE"
> On success, the new socket descriptor representing the branched-off asociation is returned.
> On error, \-1 is returned, and
> @@ -44,6 +57,9 @@ The assoc id passed is invalid or if the socket is a one-to-one style socket.
> .TP
> .B ENOTSOCK
> Argument is a descriptor for a file, not a socket.
> +.SH NOTES
> +.TP
> +sctp_peeloff_flags is a linux specific variant of sctp_peeloff. While it will compile on other systems, its use will result in an error return. Portable code should use sctp_peeloff.
> .SH "SEE ALSO"
> .BR sctp (7)
> .BR sctp_bindx (3),
> diff --git a/src/include/netinet/sctp.h b/src/include/netinet/sctp.h
> index 47571cd..560ca33 100644
> --- a/src/include/netinet/sctp.h
> +++ b/src/include/netinet/sctp.h
> @@ -111,6 +111,7 @@ typedef __s32 sctp_assoc_t;
>
> /* SCTP socket option used to read per endpoint association statistics. */
> #define SCTP_GET_ASSOC_STATS 112 /* Read only */
> +#define SCTP_SOCKOPT_PEELOFF_FLAGS 122
>
> /*
> * 5.2.1 SCTP Initiation Structure (SCTP_INIT)
> @@ -802,6 +803,10 @@ typedef struct {
> int sd;
> } sctp_peeloff_arg_t;
>
> +typedef struct {
> + sctp_peeloff_arg_t p_arg;
> + unsigned flags;
> +} sctp_peeloff_flags_arg_t;
>
> int sctp_bindx(int sd, struct sockaddr *addrs, int addrcnt, int flags);
>
> @@ -809,6 +814,7 @@ int sctp_connectx(int sd, struct sockaddr *addrs, int addrcnt,
> sctp_assoc_t *id);
>
> int sctp_peeloff(int sd, sctp_assoc_t assoc_id);
> +int sctp_peeloff_flags(int sd, sctp_assoc_t assoc_id, unsigned flags);
>
> /* Prototype for the library function sctp_opt_info defined in
> * API 7. Socket Options.
> diff --git a/src/lib/peeloff.c b/src/lib/peeloff.c
> index a870050..b9b97b1 100644
> --- a/src/lib/peeloff.c
> +++ b/src/lib/peeloff.c
> @@ -23,25 +23,39 @@
> #include <netinet/sctp.h> /* SCTP_SOCKOPT_BINDX_* */
> #include <errno.h>
>
> -/* Branch off an association into a seperate socket. This is a new SCTP API
> - * described in the section 8.2 of the Sockets API Extensions for SCTP.
> - * This is implemented using the getsockopt() interface.
> - */
> int
> -sctp_peeloff(int fd, sctp_assoc_t associd)
> +sctp_peeloff_flags(int fd, sctp_assoc_t associd, unsigned flags)
> {
> - sctp_peeloff_arg_t peeloff;
> - socklen_t peeloff_size = sizeof(peeloff);
> + sctp_peeloff_flags_arg_t peeloff;
> + socklen_t peeloff_size;
> int err;
>
> - peeloff.associd = associd;
> - peeloff.sd = 0;
> - err = getsockopt(fd, SOL_SCTP, SCTP_SOCKOPT_PEELOFF, &peeloff,
> - &peeloff_size);
> - if (err < 0) {
> + peeloff.p_arg.associd = associd;
> + peeloff.p_arg.sd = 0;
> + peeloff.flags = flags;
> +
> + peeloff_size = flags ? sizeof(sctp_peeloff_flags_arg_t) : sizeof(sctp_peeloff_arg_t);
> +
Please avoid the ?: above. As it's doing the same check as the if block
below, it makes the code confusing.
Thanks,
Marcelo
> + if (flags)
> + err = getsockopt(fd, SOL_SCTP, SCTP_SOCKOPT_PEELOFF_FLAGS, &peeloff,
> + &peeloff_size);
> + else
> + err = getsockopt(fd, SOL_SCTP, SCTP_SOCKOPT_PEELOFF, &peeloff.p_arg,
> + &peeloff_size);
> + if (err < 0)
> return err;
> - }
>
> - return peeloff.sd;
> + return peeloff.p_arg.sd;
>
> } /* sctp_peeloff() */
> +
> +/* Branch off an association into a seperate socket. This is a new SCTP API
> + * described in the section 8.2 of the Sockets API Extensions for SCTP.
> + * This is implemented using the getsockopt() interface.
> + */
> +int
> +sctp_peeloff(int fd, sctp_assoc_t associd)
> +{
> + return sctp_peeloff_flags(fd, associd, 0);
> +}
> +
> --
> 2.9.4
>
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