Add selftests to verify and document Linux’s 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’s semantics.
Suggested-by: Kuniyuki Iwashima kuniyu@google.com Signed-off-by: Sunday Adelodun adelodunolaoluwa@yahoo.com --- Changelog:
Changes made from v1:
- Patch prefix updated to selftest: af_unix:.
- All mentions of “UNIX” 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 peer 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/selftests/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 := \ scm_pidfd \ scm_rights \ unix_connect \ + unix_connreset \ # end of TEST_GEN_PROGS
include ../../lib.mk diff --git a/tools/testing/selftests/net/af_unix/unix_connreset.c b/tools/testing/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 data. + * 3. SOCK_DGRAM sockets do not return ECONNRESET when peer closes. + * + * These tests document the intended Linux behaviour. + * + */ + +#define _GNU_SOURCE +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include <unistd.h> +#include <errno.h> +#include <sys/socket.h> +#include <sys/un.h> +#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 = SOCK_STREAM, + .name = "SOCK_STREAM", +}; + +FIXTURE_VARIANT_ADD(unix_sock, dgram) { + .socket_type = SOCK_DGRAM, + .name = "SOCK_DGRAM", +}; + +FIXTURE_SETUP(unix_sock) +{ + struct sockaddr_un addr = {}; + int err; + + addr.sun_family = AF_UNIX; + strcpy(addr.sun_path, SOCK_PATH); + + self->server = socket(AF_UNIX, variant->socket_type, 0); + ASSERT_LT(-1, self->server); + + err = bind(self->server, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + if (variant->socket_type == SOCK_STREAM) { + err = listen(self->server, 1); + ASSERT_EQ(0, err); + + self->client = socket(AF_UNIX, SOCK_STREAM, 0); + ASSERT_LT(-1, self->client); + + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + + self->child = accept(self->server, NULL, NULL); + ASSERT_LT(-1, self->child); + } else { + /* Datagram: bind and connect only */ + self->client = socket(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0); + ASSERT_LT(-1, self->client); + + err = connect(self->client, (struct sockaddr *)&addr, sizeof(addr)); + ASSERT_EQ(0, err); + } +} + +FIXTURE_TEARDOWN(unix_sock) +{ + if (variant->socket_type == 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] = {}; + ssize_t n; + + if (variant->socket_type != SOCK_STREAM) + SKIP(return, "This test only applies to SOCK_STREAM"); + + /* Peer closes normally */ + close(self->child); + + n = recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno)); + if (n == -1) + ASSERT_EQ(ECONNRESET, errno); + + if (n != -1) + ASSERT_EQ(0, n); +} + +/* Test 2: peer closes with unread data */ +TEST_F(unix_sock, reset_unread) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type != 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 = recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno)); + ASSERT_EQ(-1, n); + ASSERT_EQ(ECONNRESET, errno); +} + +/* Test 3: SOCK_DGRAM peer close */ +TEST_F(unix_sock, dgram_reset) +{ + char buf[16] = {}; + ssize_t n; + + if (variant->socket_type != SOCK_DGRAM) + SKIP(return, "This test only applies to SOCK_DGRAM"); + + send(self->client, "hello", 5, 0); + close(self->server); + + n = recv(self->client, buf, sizeof(buf), 0); + TH_LOG("%s: recv=%zd errno=%d (%s)", variant->name, n, errno, strerror(errno)); + /* Expect EAGAIN because there is no datagram and peer is closed. */ + ASSERT_EQ(-1, n); + ASSERT_EQ(EAGAIN, errno); +} + +TEST_HARNESS_MAIN +