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Hermes SMTP Server) with ESMTPA ID 0ca7b4e896ed0ba71fcca8b2a04199fd; Sat, 25 Oct 2025 19:03:06 +0000 (UTC) From: Sunday Adelodun To: Kuniyuki Iwashima , "=David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan Cc: Shuah Khan , David Hunter , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Sunday Adelodun Subject: [PATCH v2] selftests: af_unix: Add tests for ECONNRESET and EOF semantics Date: Sat, 25 Oct 2025 20:02:56 +0100 Message-ID: <20251025190256.11352-1-adelodunolaoluwa@yahoo.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable References: <20251025190256.11352-1-adelodunolaoluwa.ref@yahoo.com> Add selftests to verify and document Linux=E2=80=99s intended behaviour for UNIX domain sockets (SOCK_STREAM and SOCK_DGRAM) when a peer closes. The tests cover: 1. EOF returned when a SOCK_STREAM peer closes normally. 2. ECONNRESET returned when a SOCK_STREAM peer closes with unread data. 3. SOCK_DGRAM sockets not returning ECONNRESET on peer close. This follows up on review feedback suggesting a selftest to clarify Linux=E2=80=99s semantics. Suggested-by: Kuniyuki Iwashima Signed-off-by: Sunday Adelodun --- Changelog: Changes made from v1: - Patch prefix updated to selftest: af_unix:. - All mentions of =E2=80=9CUNIX=E2=80=9D changed to AF_UNIX. - Removed BSD references from comments. - Shared setup refactored using FIXTURE_VARIANT(). - Cleanup moved to FIXTURE_TEARDOWN() to always run. - Tests consolidated to reduce duplication: EOF, ECONNRESET, SOCK_DGRAM pee= r close. - Corrected ASSERT usage and initialization style. - Makefile updated for new directory af_unix. tools/testing/selftests/net/af_unix/Makefile | 1 + .../selftests/net/af_unix/unix_connreset.c | 161 ++++++++++++++++++ 2 files changed, 162 insertions(+) create mode 100644 tools/testing/selftests/net/af_unix/unix_connreset.c diff --git a/tools/testing/selftests/net/af_unix/Makefile b/tools/testing/s= elftests/net/af_unix/Makefile index de805cbbdf69..5826a8372451 100644 --- a/tools/testing/selftests/net/af_unix/Makefile +++ b/tools/testing/selftests/net/af_unix/Makefile @@ -7,6 +7,7 @@ TEST_GEN_PROGS :=3D \ scm_pidfd \ scm_rights \ unix_connect \ + unix_connreset \ # end of TEST_GEN_PROGS =20 include ../../lib.mk diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/t= esting/selftests/net/af_unix/unix_connreset.c new file mode 100644 index 000000000000..c65ec997d77d --- /dev/null +++ b/tools/testing/selftests/net/af_unix/unix_connreset.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Selftest for AF_UNIX socket close and ECONNRESET behaviour. + * + * This test verifies that: + * 1. SOCK_STREAM sockets return EOF when peer closes normally. + * 2. SOCK_STREAM sockets return ECONNRESET if peer closes with unread da= ta. + * 3. SOCK_DGRAM sockets do not return ECONNRESET when peer closes. + * + * These tests document the intended Linux behaviour. + * + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include "../../kselftest_harness.h" + +#define SOCK_PATH "/tmp/af_unix_connreset.sock" + +static void remove_socket_file(void) +{ + unlink(SOCK_PATH); +} + +FIXTURE(unix_sock) +{ + int server; + int client; + int child; +}; + +FIXTURE_VARIANT(unix_sock) +{ + int socket_type; + const char *name; +}; + +/* Define variants: stream and datagram */ +FIXTURE_VARIANT_ADD(unix_sock, stream) { + .socket_type =3D SOCK_STREAM, + .name =3D "SOCK_STREAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, dgram) { + .socket_type =3D SOCK_DGRAM, + .name =3D "SOCK_DGRAM", +}; + +FIXTURE_SETUP(unix_sock) +{ + struct sockaddr_un addr =3D {}; + int err; + + addr.sun_family =3D AF_UNIX; + strcpy(addr.sun_path, SOCK_PATH); + + self->server =3D socket(AF_UNIX, variant->socket_type, 0); + ASSERT_LT(-1, self->server); + + err =3D bind(self->server, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + if (variant->socket_type =3D=3D SOCK_STREAM) { + err =3D listen(self->server, 1); + ASSERT_EQ(0, err); + + self->client =3D socket(AF_UNIX, SOCK_STREAM, 0); + ASSERT_LT(-1, self->client); + + err =3D connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + self->child =3D accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + } else { + /* Datagram: bind and connect only */ + self->client =3D socket(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0); + ASSERT_LT(-1, self->client); + + err =3D connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + } +} + +FIXTURE_TEARDOWN(unix_sock) +{ + if (variant->socket_type =3D=3D SOCK_STREAM) + close(self->child); + + close(self->client); + close(self->server); + remove_socket_file(); +} + +/* Test 1: peer closes normally */ +TEST_F(unix_sock, eof) +{ + char buf[16] =3D {}; + ssize_t n; + + if (variant->socket_type !=3D SOCK_STREAM) + SKIP(return, "This test only applies to SOCK_STREAM"); + + /* Peer closes normally */ + close(self->child); + + n =3D recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=3D%zd errno=3D%d (%s)", variant->name, n, errno, strerro= r(errno)); + if (n =3D=3D -1) + ASSERT_EQ(ECONNRESET, errno); + + if (n !=3D -1) + ASSERT_EQ(0, n); +} + +/* Test 2: peer closes with unread data */ +TEST_F(unix_sock, reset_unread) +{ + char buf[16] =3D {}; + ssize_t n; + + if (variant->socket_type !=3D SOCK_STREAM) + SKIP(return, "This test only applies to SOCK_STREAM"); + + /* Send data that will remain unread by client */ + send(self->client, "hello", 5, 0); + close(self->child); + + n =3D recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=3D%zd errno=3D%d (%s)", variant->name, n, errno, strerro= r(errno)); + ASSERT_EQ(-1, n); + ASSERT_EQ(ECONNRESET, errno); +} + +/* Test 3: SOCK_DGRAM peer close */ +TEST_F(unix_sock, dgram_reset) +{ + char buf[16] =3D {}; + ssize_t n; + + if (variant->socket_type !=3D SOCK_DGRAM) + SKIP(return, "This test only applies to SOCK_DGRAM"); + + send(self->client, "hello", 5, 0); + close(self->server); + + n =3D recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=3D%zd errno=3D%d (%s)", variant->name, n, errno, strerro= r(errno)); + /* Expect EAGAIN because there is no datagram and peer is closed. */ + ASSERT_EQ(-1, n); + ASSERT_EQ(EAGAIN, errno); +} + +TEST_HARNESS_MAIN + --=20 2.43.0