From patchwork Wed Dec 18 05:34:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiayuan Chen X-Patchwork-Id: 13913061 X-Patchwork-Delegate: bpf@iogearbox.net Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.2]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 492821474C9; Wed, 18 Dec 2024 05:36:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.2 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734500202; cv=none; b=KWQnPXQYRY7maWRZ7xeeCIuYigArpm4g6b/fuLt5U6dl5IkQrJzh11iJrlXSKEtqtwWwoEVERRNOjxqEA1zvUZQ7BahZ+1CBH2O4Hm3QoucLgKA0SJD+mmsASU3e0pdCb+MHKzErflCRDYV/F4KYja8KXIbHqg3IDa7UUU12XCQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734500202; c=relaxed/simple; bh=dIUP7WdiNL+gacq4RzMEJCyL7wZSCrcOzOwR8uvJg2E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZH36NvC88n/jGWXYvSSYFF/g30gmwsU24ck6uSyskJ5ZXKKMWMAow7MYqCBCPjmFHi9hPZVHPIcNmbosItx4HtnXSCMwsUa92IrQelV+2xKBSZ9miUAlvvx66GD/Z0XClE/hKX9SdJIor19GiCRbtbwKbEa1mfCNay2KuKfr3jU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=PjL4cx0d; arc=none smtp.client-ip=117.135.210.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="PjL4cx0d" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-ID:MIME-Version; bh=iC8jk 3Ez3kXmPN1ZIXjPdlYnL0nYGf90nwsAxr8CmYg=; b=PjL4cx0dFWsTzG+M7lGll R59H3nNT7oOleWAGIS+tgLIkClAzoj6/CMeIVEPpcQCeAATMqOAnih3hFVE1vWS9 6vuafgCVBucg+CkmcnzHpSFc/Ar5n+e2H2J9UQ6iDGGRx+1EUwLVCQixFVjutfPA NXYm1UuYoPuY4F6CubceHk= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g1-2 (Coremail) with SMTP id _____wDXf3juXmJn1VZZBQ--.30577S4; Wed, 18 Dec 2024 13:35:05 +0800 (CST) From: Jiayuan Chen To: bpf@vger.kernel.org Cc: martin.lau@linux.dev, ast@kernel.org, edumazet@google.com, jakub@cloudflare.com, davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org, song@kernel.org, john.fastabend@gmail.com, andrii@kernel.org, mhal@rbox.co, yonghong.song@linux.dev, daniel@iogearbox.net, xiyou.wangcong@gmail.com, horms@kernel.org, Jiayuan Chen Subject: [PATCH bpf v3 2/2] selftests/bpf: add strparser test for bpf Date: Wed, 18 Dec 2024 13:34:08 +0800 Message-ID: <20241218053408.437295-3-mrpre@163.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20241218053408.437295-1-mrpre@163.com> References: <20241218053408.437295-1-mrpre@163.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: _____wDXf3juXmJn1VZZBQ--.30577S4 X-Coremail-Antispam: 1Uf129KBjvAXoWfGF1fXr18Cw1DJw1fJFyrJFb_yoW8WF13Co Z3Gan8J3yxGrnxJ34kG3yDCa1fWF4xWw4kWw47J3y5XFyjyrWj9ayUGws3W3Wa9r4Sgr93 JFWqva4rWr15Jr4fn29KB7ZKAUJUUUU8529EdanIXcx71UUUUU7v73VFW2AGmfu7bjvjm3 AaLaJ3UbIYCTnIWIevJa73UjIFyTuYvj4RPWrWUUUUU X-CM-SenderInfo: xpus2vi6rwjhhfrp/1tbiWxC5p2diVznRhwAAso X-Patchwork-Delegate: bpf@iogearbox.net Add test cases for bpf + strparser and separated them from sockmap_basic. This is because we need to add more test cases for strparser in the future. Signed-off-by: Jiayuan Chen --- .../selftests/bpf/prog_tests/sockmap_basic.c | 53 --- .../selftests/bpf/prog_tests/sockmap_strp.c | 344 ++++++++++++++++++ .../selftests/bpf/progs/test_sockmap_strp.c | 51 +++ 3 files changed, 395 insertions(+), 53 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/sockmap_strp.c create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_strp.c diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c index fdff0652d7ef..4c0eebc433d8 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c @@ -530,57 +530,6 @@ static void test_sockmap_skb_verdict_shutdown(void) test_sockmap_pass_prog__destroy(skel); } -static void test_sockmap_stream_pass(void) -{ - int zero = 0, sent, recvd; - int verdict, parser; - int err, map; - int c = -1, p = -1; - struct test_sockmap_pass_prog *pass = NULL; - char snd[256] = "0123456789"; - char rcv[256] = "0"; - - pass = test_sockmap_pass_prog__open_and_load(); - verdict = bpf_program__fd(pass->progs.prog_skb_verdict); - parser = bpf_program__fd(pass->progs.prog_skb_parser); - map = bpf_map__fd(pass->maps.sock_map_rx); - - err = bpf_prog_attach(parser, map, BPF_SK_SKB_STREAM_PARSER, 0); - if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) - goto out; - - err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0); - if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) - goto out; - - err = create_pair(AF_INET, SOCK_STREAM, &c, &p); - if (err) - goto out; - - /* sk_data_ready of 'p' will be replaced by strparser handler */ - err = bpf_map_update_elem(map, &zero, &p, BPF_NOEXIST); - if (!ASSERT_OK(err, "bpf_map_update_elem(p)")) - goto out_close; - - /* - * as 'prog_skb_parser' return the original skb len and - * 'prog_skb_verdict' return SK_PASS, the kernel will just - * pass it through to original socket 'p' - */ - sent = xsend(c, snd, sizeof(snd), 0); - ASSERT_EQ(sent, sizeof(snd), "xsend(c)"); - - recvd = recv_timeout(p, rcv, sizeof(rcv), SOCK_NONBLOCK, - IO_TIMEOUT_SEC); - ASSERT_EQ(recvd, sizeof(rcv), "recv_timeout(p)"); - -out_close: - close(c); - close(p); - -out: - test_sockmap_pass_prog__destroy(pass); -} static void test_sockmap_skb_verdict_fionread(bool pass_prog) { @@ -1050,8 +999,6 @@ void test_sockmap_basic(void) test_sockmap_progs_query(BPF_SK_SKB_VERDICT); if (test__start_subtest("sockmap skb_verdict shutdown")) test_sockmap_skb_verdict_shutdown(); - if (test__start_subtest("sockmap stream parser and verdict pass")) - test_sockmap_stream_pass(); if (test__start_subtest("sockmap skb_verdict fionread")) test_sockmap_skb_verdict_fionread(true); if (test__start_subtest("sockmap skb_verdict fionread on drop")) diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_strp.c b/tools/testing/selftests/bpf/prog_tests/sockmap_strp.c new file mode 100644 index 000000000000..0398658d4787 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_strp.c @@ -0,0 +1,344 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +#include +#include "sockmap_helpers.h" +#include "test_skmsg_load_helpers.skel.h" +#include "test_sockmap_strp.skel.h" +#define STRP_PACKET_HEAD_LEN 4 +#define STRP_PACKET_BODY_LEN 6 +#define STRP_PACKET_FULL_LEN (STRP_PACKET_HEAD_LEN + STRP_PACKET_BODY_LEN) +static const char packet[STRP_PACKET_FULL_LEN] = "head+body\0"; +static const int test_packet_num = 100; + +static struct test_sockmap_strp *sockmap_strp_init(int *map) +{ + struct test_sockmap_strp *strp = NULL; + int verdict, parser; + int err; + + strp = test_sockmap_strp__open_and_load(); + verdict = bpf_program__fd(strp->progs.prog_skb_verdict_pass); + parser = bpf_program__fd(strp->progs.prog_skb_parser_partial); + *map = bpf_map__fd(strp->maps.sock_map); + + err = bpf_prog_attach(parser, *map, BPF_SK_SKB_STREAM_PARSER, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) + goto err; + + err = bpf_prog_attach(verdict, *map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) + goto err; + + return strp; +err: + test_sockmap_strp__destroy(strp); + return NULL; +} + +/* we have multiple packets in one skb + * ------------ ------------ ------------ + * | packet1 | packet2 | ... + * ------------ ------------ ------------ + */ +static void test_sockmap_strp_multi_packet(int family, int sotype) +{ + int i, zero = 0; + int sent, recvd, total; + int err, map; + int c = -1, p = -1; + struct test_sockmap_strp *strp = NULL; + char *snd = NULL, *rcv = NULL; + + strp = sockmap_strp_init(&map); + if (!ASSERT_TRUE(strp != NULL, "sockmap_strp_init")) + return; + + err = create_pair(family, sotype, &c, &p); + if (err) + goto out; + + err = bpf_map_update_elem(map, &zero, &p, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(zero, p)")) + goto out_close; + + /* construct multiple packets in one buffer */ + total = test_packet_num * STRP_PACKET_FULL_LEN; + snd = malloc(total); + rcv = malloc(total + 1); + if (!ASSERT_TRUE(snd != NULL, "malloc(multi block)") + || !ASSERT_TRUE(rcv != NULL, "malloc(multi block)")) + goto out_close; + + for (i = 0; i < test_packet_num; i++) { + memcpy(snd + i * STRP_PACKET_FULL_LEN, + packet, STRP_PACKET_FULL_LEN); + } + + sent = xsend(c, snd, total, 0); + if (!ASSERT_EQ(sent, total, "xsend(c)")) + goto out_close; + + /* try to recv one more byte to avoid truncation check */ + recvd = recv_timeout(p, rcv, total + 1, MSG_DONTWAIT, IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, total, "recv(rcv)")) + goto out_close; + + /* we sent TCP segment with multiple encapsulation + * then check whether packets are handled correctly + */ + if (!ASSERT_OK(memcmp(snd, rcv, total), "memcmp(snd, rcv)")) + goto out_close; + +out_close: + close(c); + close(p); + if (snd) + free(snd); + if (rcv) + free(rcv); +out: + test_sockmap_strp__destroy(strp); +} + +static void test_sockmap_strp_partial_read(int family, int sotype) +{ + int zero = 0, recvd, off; + int verdict, parser; + int err, map; + int c = -1, p = -1; + struct test_sockmap_strp *strp = NULL; + char rcv[STRP_PACKET_FULL_LEN + 1] = "0"; + + strp = test_sockmap_strp__open_and_load(); + verdict = bpf_program__fd(strp->progs.prog_skb_verdict_pass); + parser = bpf_program__fd(strp->progs.prog_skb_parser_partial); + map = bpf_map__fd(strp->maps.sock_map); + + err = bpf_prog_attach(parser, map, BPF_SK_SKB_STREAM_PARSER, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) + goto out; + + err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) + goto out; + + err = create_pair(family, sotype, &c, &p); + if (err) + goto out; + + /* sk_data_ready of 'p' will be replaced by strparser handler */ + err = bpf_map_update_elem(map, &zero, &p, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(zero, p)")) + goto out_close; + + /* 1.1 send partial head, 1 byte header left*/ + off = STRP_PACKET_HEAD_LEN - 1; + xsend(c, packet, off, 0); + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, 5); + if (!ASSERT_EQ(-1, recvd, "insufficient head, should no data recvd")) + goto out_close; + + /* 1.2 send remaining head and body */ + xsend(c, packet + off, STRP_PACKET_FULL_LEN - off, 0); + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, STRP_PACKET_FULL_LEN, "should full data recvd")) + goto out_close; + + /* 2.1 send partial head, 1 byte header left */ + off = STRP_PACKET_HEAD_LEN - 1; + xsend(c, packet, off, 0); + + /* 2.2 send remaining head and partial body, 1 byte body left */ + xsend(c, packet + off, STRP_PACKET_FULL_LEN - off - 1, 0); + off = STRP_PACKET_FULL_LEN - 1; + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, 1); + if (!ASSERT_EQ(-1, recvd, "insufficient body, should no data read")) + goto out_close; + + /* 2.3 send remaining body */ + xsend(c, packet + off, STRP_PACKET_FULL_LEN - off, 0); + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, STRP_PACKET_FULL_LEN, "should full data recvd")) + goto out_close; + +out_close: + close(c); + close(p); + +out: + test_sockmap_strp__destroy(strp); +} + +static void test_sockmap_strp_pass(int family, int sotype, bool fionread) +{ + int zero = 0, pkt_size, sent, recvd, avail; + int verdict, parser; + int err, map; + int c = -1, p = -1; + int read_cnt = 10, i; + struct test_sockmap_strp *strp = NULL; + char rcv[STRP_PACKET_FULL_LEN + 1] = "0"; + + strp = test_sockmap_strp__open_and_load(); + verdict = bpf_program__fd(strp->progs.prog_skb_verdict_pass); + parser = bpf_program__fd(strp->progs.prog_skb_parser); + map = bpf_map__fd(strp->maps.sock_map); + + err = bpf_prog_attach(parser, map, BPF_SK_SKB_STREAM_PARSER, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) + goto out; + + err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) + goto out; + + err = create_pair(family, sotype, &c, &p); + if (err) + goto out; + + /* sk_data_ready of 'p' will be replaced by strparser handler */ + err = bpf_map_update_elem(map, &zero, &p, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(p)")) + goto out_close; + + /* Previously, we encountered issues such as deadlocks and + * sequence errors that resulted in the inability to read + * continuously. Therefore, we perform multiple iterations + * of testing here. + */ + pkt_size = STRP_PACKET_FULL_LEN; + for (i = 0; i < read_cnt; i++) { + sent = xsend(c, packet, pkt_size, 0); + if (!ASSERT_EQ(sent, pkt_size, "xsend(c)")) + goto out_close; + + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, + IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, pkt_size, "recv_timeout(p)") + || !ASSERT_OK(memcmp(packet, rcv, pkt_size), + "recv_timeout(p)")) + goto out_close; + } + + if (fionread) { + sent = xsend(c, packet, pkt_size, 0); + if (!ASSERT_EQ(sent, pkt_size, "second xsend(c)")) + goto out_close; + + err = ioctl(p, FIONREAD, &avail); + if (!ASSERT_OK(err, "ioctl(FIONREAD) error") + || ASSERT_EQ(avail, pkt_size, "ioctl(FIONREAD)")) + goto out_close; + + recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, + IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, pkt_size, "second recv_timeout(p)") + || ASSERT_OK(memcmp(packet, rcv, pkt_size), + "second recv_timeout(p)")) + goto out_close; + } + +out_close: + close(c); + close(p); + +out: + test_sockmap_strp__destroy(strp); +} + +static void test_sockmap_strp_verdict(int family, int sotype) +{ + int zero = 0, one = 1, sent, recvd, off; + int verdict, parser; + int err, map; + int c0 = -1, p0 = -1, c1 = -1, p1 = -1; + struct test_sockmap_strp *strp = NULL; + char rcv[STRP_PACKET_FULL_LEN + 1] = "0"; + + strp = test_sockmap_strp__open_and_load(); + verdict = bpf_program__fd(strp->progs.prog_skb_verdict); + parser = bpf_program__fd(strp->progs.prog_skb_parser); + map = bpf_map__fd(strp->maps.sock_map); + + err = bpf_prog_attach(parser, map, BPF_SK_SKB_STREAM_PARSER, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream parser")) + goto out; + + err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0); + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) + goto out; + + /* We simulate a reverse proxy server. + * When p0 receives data from c0, we forward it to p1. + * From p1's perspective, it will consider this data + * as being sent by c1. + */ + err = create_socket_pairs(family, sotype, &c0, &c1, &p0, &p1); + if (!ASSERT_OK(err, "create_socket_pairs()")) + goto out; + + err = bpf_map_update_elem(map, &zero, &p0, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(p0)")) + goto out_close; + + err = bpf_map_update_elem(map, &one, &c1, BPF_NOEXIST); + if (!ASSERT_OK(err, "bpf_map_update_elem(c1)")) + goto out_close; + + sent = xsend(c0, packet, STRP_PACKET_FULL_LEN, 0); + if (!ASSERT_EQ(sent, STRP_PACKET_FULL_LEN, "xsend(c0)")) + goto out_close; + + recvd = recv_timeout(p1, rcv, sizeof(rcv), MSG_DONTWAIT, + IO_TIMEOUT_SEC); + if (!ASSERT_EQ(recvd, STRP_PACKET_FULL_LEN, "recv_timeout(p1)") + || !ASSERT_OK(memcmp(packet, rcv, STRP_PACKET_FULL_LEN), + "received data does not match the sent data")) + goto out_close; + + /* send again to ensure the stream is functioning correctly. */ + sent = xsend(c0, packet, STRP_PACKET_FULL_LEN, 0); + if (!ASSERT_EQ(sent, STRP_PACKET_FULL_LEN, "second xsend(c0)")) + goto out_close; + + /* partial read */ + off = STRP_PACKET_FULL_LEN/2; + recvd = recv_timeout(p1, rcv, off, MSG_DONTWAIT, + IO_TIMEOUT_SEC); + recvd += recv_timeout(p1, rcv + off, sizeof(rcv) - off, MSG_DONTWAIT, + IO_TIMEOUT_SEC); + + if (!ASSERT_EQ(recvd, STRP_PACKET_FULL_LEN, "partial recv_timeout(p1)") + || !ASSERT_OK(memcmp(packet, rcv, STRP_PACKET_FULL_LEN), + "partial received data does not match the sent data")) + goto out_close; + +out_close: + close(c0); + close(c1); + close(p0); + close(p1); +out: + test_sockmap_strp__destroy(strp); +} + +void test_sockmap_strp(void) +{ + if (test__start_subtest("sockmap strp tcp pass")) + test_sockmap_strp_pass(AF_INET, SOCK_STREAM, false); + if (test__start_subtest("sockmap strp tcp v6 pass")) + test_sockmap_strp_pass(AF_INET6, SOCK_STREAM, false); + if (test__start_subtest("sockmap strp tcp pass fionread")) + test_sockmap_strp_pass(AF_INET, SOCK_STREAM, true); + if (test__start_subtest("sockmap strp tcp v6 pass fionread")) + test_sockmap_strp_pass(AF_INET6, SOCK_STREAM, true); + if (test__start_subtest("sockmap strp tcp verdict")) + test_sockmap_strp_verdict(AF_INET, SOCK_STREAM); + if (test__start_subtest("sockmap strp tcp v6 verdict")) + test_sockmap_strp_verdict(AF_INET6, SOCK_STREAM); + if (test__start_subtest("sockmap strp tcp partial read")) + test_sockmap_strp_partial_read(AF_INET, SOCK_STREAM); + if (test__start_subtest("sockmap strp tcp multiple packets")) + test_sockmap_strp_multi_packet(AF_INET, SOCK_STREAM); +} diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_strp.c b/tools/testing/selftests/bpf/progs/test_sockmap_strp.c new file mode 100644 index 000000000000..db2f3b6c87ba --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_sockmap_strp.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_SOCKMAP); + __uint(max_entries, 20); + __type(key, int); + __type(value, int); +} sock_map SEC(".maps"); + + +SEC("sk_skb/stream_verdict") +int prog_skb_verdict_pass(struct __sk_buff *skb) +{ + return SK_PASS; +} + + +SEC("sk_skb/stream_verdict") +int prog_skb_verdict(struct __sk_buff *skb) +{ + __u32 one = 1; + + return bpf_sk_redirect_map(skb, &sock_map, one, 0); +} + +SEC("sk_skb/stream_parser") +int prog_skb_parser(struct __sk_buff *skb) +{ + return skb->len; +} + +SEC("sk_skb/stream_parser") +int prog_skb_parser_partial(struct __sk_buff *skb) +{ + /* agreement with the test program on a 4-byte size header + * and 6-byte body. + */ + if (skb->len < 4) { + /* need more header to determine full length */ + return 0; + } + /* return full length decoded from header. + * the return value may be larger than skb->len which + * means framework must wait body coming. + */ + return 10; +} +char _license[] SEC("license") = "GPL";