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Message-Id: <1493695105-9418-3-git-send-email-dsa@cumulusnetworks.com> Date: Mon, 1 May 2017 20:18:24 -0700 From: David Ahern <dsa@...ulusnetworks.com> To: netdev@...r.kernel.org, stephen@...workplumber.org Cc: jakub.kicinski@...ronome.com, David Ahern <dsa@...ulusnetworks.com> Subject: [PATCH net-next iproute2 2/3] netlink: Add support for extended ack to rtnl_talk Add support for extended ack error reporting. Add a new function rtnl_talk_extack that takes a callback as an input arg. If a netlink response contains extack attributes, the callback is is invoked with the the err string, offset in the message and a pointer to the message returned by the kernel. Adding a new function allows commands to be moved over to the extended error reporting over time. Signed-off-by: David Ahern <dsa@...ulusnetworks.com> --- include/libnetlink.h | 6 ++++ lib/libnetlink.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 91 insertions(+), 7 deletions(-) diff --git a/include/libnetlink.h b/include/libnetlink.h index e7c46f1870aa..6b031454ce2b 100644 --- a/include/libnetlink.h +++ b/include/libnetlink.h @@ -71,6 +71,9 @@ typedef int (*rtnl_listen_filter_t)(const struct sockaddr_nl *, struct rtnl_ctrl_data *, struct nlmsghdr *n, void *); +typedef int (*nl_ext_ack_fn_t)(const char *errmsg, __u32 off, + struct nlmsghdr *inner_nlh); + struct rtnl_dump_filter_arg { rtnl_filter_t filter; void *arg1; @@ -87,6 +90,9 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth, int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, struct nlmsghdr *answer, size_t len) __attribute__((warn_unused_result)); +int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n, + struct nlmsghdr *answer, size_t len, nl_ext_ack_fn_t errfn) + __attribute__((warn_unused_result)); int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n, struct nlmsghdr *answer, size_t len) __attribute__((warn_unused_result)); diff --git a/lib/libnetlink.c b/lib/libnetlink.c index b5ee751c6b86..f6451dec1332 100644 --- a/lib/libnetlink.c +++ b/lib/libnetlink.c @@ -32,6 +32,61 @@ int rcvbuf = 1024 * 1024; +/* dump netlink extended ack error message */ +static int nl_dump_ext_err(struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn) +{ + const struct nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = { + [NLMSGERR_ATTR_MSG] = { .type = NLA_STRING }, + [NLMSGERR_ATTR_OFFS] = { .type = NLA_U32 }, + }; + struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr; + struct nlmsghdr *err_nlh = NULL; + struct nlmsgerr *err; + char *errmsg = NULL; + int hlen, alen; + __u32 off = 0; + + if (!errfn) + return 0; + + /* no TLVs, nothing to do here */ + if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS)) + return 0; + + err = (struct nlmsgerr *)NLMSG_DATA(nlh); + hlen = sizeof(*err); + + /* if NLM_F_CAPPED is set then the inner err msg was capped */ + if (!(nlh->nlmsg_flags & NLM_F_CAPPED)) + hlen += nlmsg_len(&err->msg); + + attr = (struct nlattr *) ((void *) err + hlen); + alen = nlh->nlmsg_len - hlen; + + if (nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen, extack_policy) != 0) { + fprintf(stderr, + "Failed to parse extended error attributes\n"); + return 0; + } + + + if (tb[NLMSGERR_ATTR_MSG]) + errmsg = (char *) nla_data(tb[NLMSGERR_ATTR_MSG]); + + if (tb[NLMSGERR_ATTR_OFFS]) { + off = nla_get_u32(tb[NLMSGERR_ATTR_OFFS]); + + if (off > nlh->nlmsg_len) { + fprintf(stderr, + "Invalid offset for NLMSGERR_ATTR_OFFS\n"); + off = 0; + } else if (!(nlh->nlmsg_flags & NLM_F_CAPPED)) + err_nlh = &err->msg; + } + + return errfn(errmsg, off, err_nlh); +} + void rtnl_close(struct rtnl_handle *rth) { if (rth->fd >= 0) { @@ -45,6 +100,7 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions, { socklen_t addr_len; int sndbuf = 32768; + int one = 1; memset(rth, 0, sizeof(*rth)); @@ -67,6 +123,11 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions, return -1; } + if (setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK, + &one, sizeof(one)) < 0) { + /* debug/verbose message that it is not supported */ + } + memset(&rth->local, 0, sizeof(rth->local)); rth->local.nl_family = AF_NETLINK; rth->local.nl_groups = subscriptions; @@ -413,9 +474,19 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth, return rtnl_dump_filter_l(rth, a); } +static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err, + nl_ext_ack_fn_t errfn) +{ + if (nl_dump_ext_err(h, errfn)) + return; + + fprintf(stderr, "RTNETLINK answers: %s\n", + strerror(-err->error)); +} + static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, struct nlmsghdr *answer, size_t maxlen, - bool show_rtnl_err) + bool show_rtnl_err, nl_ext_ack_fn_t errfn) { int status; unsigned int seq; @@ -502,10 +573,10 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, return 0; } - if (rtnl->proto != NETLINK_SOCK_DIAG && show_rtnl_err) - fprintf(stderr, - "RTNETLINK answers: %s\n", - strerror(-err->error)); + if (rtnl->proto != NETLINK_SOCK_DIAG && + show_rtnl_err) + rtnl_talk_error(h, err, errfn); + errno = -err->error; return -1; } @@ -537,13 +608,20 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, struct nlmsghdr *answer, size_t maxlen) { - return __rtnl_talk(rtnl, n, answer, maxlen, true); + return __rtnl_talk(rtnl, n, answer, maxlen, true, NULL); +} + +int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n, + struct nlmsghdr *answer, size_t maxlen, + nl_ext_ack_fn_t errfn) +{ + return __rtnl_talk(rtnl, n, answer, maxlen, true, errfn); } int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n, struct nlmsghdr *answer, size_t maxlen) { - return __rtnl_talk(rtnl, n, answer, maxlen, false); + return __rtnl_talk(rtnl, n, answer, maxlen, false, NULL); } int rtnl_listen_all_nsid(struct rtnl_handle *rth) -- 2.1.4
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