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tree-wide: introduce new SOCKADDR_UN_LEN() macro, and use it everywhere

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The macro determines the right length of a AF_UNIX "struct sockaddr_un" to pass to
connect() or bind(). It automatically figures out if the socket refers to an
abstract namespace socket, or a socket in the file system, and properly handles
the full length of the path field.

This macro is not only safer, but also simpler to use, than the usual
offsetof() + strlen() logic.
This commit is contained in:
Lennart Poettering
2016-05-05 22:24:36 +02:00
parent d8fdc62037
commit fc2fffe770
23 changed files with 87 additions and 75 deletions
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6
src/basic/log.c
View File

@@ -165,7 +165,7 @@ static int log_open_syslog(void) {
goto fail;
}
if (connect(syslog_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
if (connect(syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
safe_close(syslog_fd);
/* Some legacy syslog systems still use stream
@@ -177,7 +177,7 @@ static int log_open_syslog(void) {
goto fail;
}
if (connect(syslog_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
if (connect(syslog_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
r = -errno;
goto fail;
}
@@ -215,7 +215,7 @@ static int log_open_journal(void) {
goto fail;
}
if (connect(journal_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
if (connect(journal_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0) {
r = -errno;
goto fail;
}

11
src/basic/socket-util.h
View File

@@ -137,3 +137,14 @@ ssize_t next_datagram_size_fd(int fd);
#define CMSG_FOREACH(cmsg, mh) \
for ((cmsg) = CMSG_FIRSTHDR(mh); (cmsg); (cmsg) = CMSG_NXTHDR((mh), (cmsg)))
/* Covers only file system and abstract AF_UNIX socket addresses, but not unnamed socket addresses. */
#define SOCKADDR_UN_LEN(sa) \
({ \
const struct sockaddr_un *_sa = &(sa); \
assert(_sa->sun_family == AF_UNIX); \
offsetof(struct sockaddr_un, sun_path) + \
(_sa->sun_path[0] == 0 ? \
1 + strnlen(_sa->sun_path+1, sizeof(_sa->sun_path)-1) : \
strnlen(_sa->sun_path, sizeof(_sa->sun_path))); \
})