[PATCHv3 1/2] Support unix sockets in -yy option
Masatake YAMATO
yamato at redhat.com
Wed Dec 24 11:57:08 UTC 2014
This patch extends -yy option; the peer address of a unix socket can be
printed like an inet socket.
About a listening socket, its socket inode and socket path are printed.
About an accepted socket, its socket inode, the peer inode, and the
socket path are printed.
About a client socket, its socket inode and the peer inode are printed.
An example of server side with netcat:
$ ./strace -yy -e network nc -l -U /tmp/example.sock
socket(PF_LOCAL, SOCK_STREAM, 0) = 3
setsockopt(3<UNIX:[14728348]>, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
bind(3<UNIX:[14728348]>, {sa_family=AF_LOCAL, sun_path="/tmp/example.sock"}, 19) = 0
listen(3<UNIX:[14728348,"/tmp/example.sock"]>, 10) = 0
accept(3<UNIX:[14728348,"/tmp/example.sock"]>, {sa_family=AF_LOCAL, NULL}, [2]) = 4<UNIX:[14727246->14727245,"/tmp/example.sock"]>
recvfrom(4<UNIX:[14727246->14727245,"/tmp/example.sock"]>, "INPUT\n", 8192, 0, NULL, NULL) = 6
INPUT
An example of client side with netcat:
$ ./strace -yy -e network nc -U /tmp/example.sock
socket(PF_LOCAL, SOCK_STREAM, 0) = 3
connect(3<UNIX:[14727245]>, {sa_family=AF_LOCAL, sun_path="/tmp/example.sock"}, 19) = 0
getsockopt(3<UNIX:[14727245]>, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
INPUT
...
sendto(3<UNIX:[14727245->14727246]>, "INPUT\n", 6, 0, NULL, 0) = 6
* socketutils.c (unix_print): New function.
(unix_send_query): New function.
(inet_send_query): Rename send_query.
(unix_parse_response): New function.
(inet_parse_response): Rename parse_response.
(print_sockaddr_by_inode): Call unix_print.
Replace NETLINK_INET_DIAG with NETLINK_SOCK_DIAG.
The values of the both names are the same but
NETLINK_SOCK_DIAG impresses people as more generic
name.
(receive_responses): Add a new argument named parser.
parser deals with the protocol specific evaluation
of data parts of diag messages.
* linux/unix_diag.h: New file.
changes in v2 patch:
* Change the output format,
* Remove shrunk version of rtnelink.h.
changes in v3 patch:
* Use uintN_t instead of _uN (N = 8, 16, and 32) in unix_diag_req definition.
* Remove incorrect comment about including file.
* Define UNIX_PATH_MAX as an value calculated from sockaddr_un.
* Remove unnecessary code for initizliing a field in structure literal.
* Surround "or" operators with spaces.
* Unify the variable name convention (s/rtalen/rta_len/).
* Remove redundant local variables in unix_parse_response.
* Remove redundant branch in unix_parse_response.
* Put brances on line after.
* Rename local variable `l' to `path_len'.
* Decode a path for abstract unix socket in the same way as in `printsock' does'.
Signed-off-by: Masatake YAMATO <yamato at redhat.com>
---
linux/unix_diag.h | 25 +++++++++++
socketutils.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 148 insertions(+), 7 deletions(-)
create mode 100644 linux/unix_diag.h
diff --git a/linux/unix_diag.h b/linux/unix_diag.h
new file mode 100644
index 0000000..3329ccb
--- /dev/null
+++ b/linux/unix_diag.h
@@ -0,0 +1,25 @@
+struct unix_diag_req {
+ uint8_t sdiag_family;
+ uint8_t sdiag_protocol;
+ uint16_t pad;
+ uint32_t udiag_states;
+ uint32_t udiag_ino;
+ uint32_t udiag_show;
+ uint32_t udiag_cookie[2];
+};
+
+#define UDIAG_SHOW_NAME 0x00000001
+#define UDIAG_SHOW_PEER 0x00000004
+
+struct unix_diag_msg {
+ uint8_t udiag_family;
+ uint8_t udiag_type;
+ uint8_t udiag_state;
+ uint8_t pad;
+
+ uint32_t udiag_ino;
+ uint32_t udiag_cookie[2];
+};
+
+#define UNIX_DIAG_NAME 0
+#define UNIX_DIAG_PEER 2
diff --git a/socketutils.c b/socketutils.c
index f57c304..fbc8515 100644
--- a/socketutils.c
+++ b/socketutils.c
@@ -5,9 +5,16 @@
#include <linux/netlink.h>
#include <linux/sock_diag.h>
#include <linux/inet_diag.h>
+#include <linux/unix_diag.h>
+#include <linux/rtnetlink.h>
+
+#include <sys/un.h>
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *)0)->sun_path)
+#endif
static bool
-send_query(const int fd, const int family, const int proto)
+inet_send_query(const int fd, const int family, const int proto)
{
struct sockaddr_nl nladdr = {
.nl_family = AF_NETLINK
@@ -49,8 +56,9 @@ send_query(const int fd, const int family, const int proto)
}
static bool
-parse_response(const struct inet_diag_msg *diag_msg, const unsigned long inode)
+inet_parse_response(const void *data, int data_len, const unsigned long inode)
{
+ const struct inet_diag_msg *diag_msg = data;
static const char zero_addr[sizeof(struct in6_addr)];
socklen_t addr_size, text_size;
@@ -95,7 +103,8 @@ parse_response(const struct inet_diag_msg *diag_msg, const unsigned long inode)
}
static bool
-receive_responses(const int fd, const unsigned long inode)
+receive_responses(const int fd, const unsigned long inode,
+ bool (* parser) (const void*, int, const unsigned long))
{
static char buf[8192];
struct sockaddr_nl nladdr = {
@@ -132,7 +141,7 @@ receive_responses(const int fd, const unsigned long inode)
case NLMSG_ERROR:
return false;
}
- if (parse_response(NLMSG_DATA(h), inode))
+ if (parser(NLMSG_DATA(h), h->nlmsg_len, inode))
return true;
}
}
@@ -141,10 +150,115 @@ receive_responses(const int fd, const unsigned long inode)
static bool
inet_print(int fd, int family, int protocol, const unsigned long inode)
{
- return send_query(fd, family, protocol)
- && receive_responses(fd, inode);
+ return inet_send_query(fd, family, protocol)
+ && receive_responses(fd, inode, inet_parse_response);
+}
+
+
+static bool
+unix_send_query(const int fd, const unsigned long inode)
+{
+ struct sockaddr_nl nladdr = {
+ .nl_family = AF_NETLINK
+ };
+ struct {
+ struct nlmsghdr nlh;
+ struct unix_diag_req udr;
+ } req = {
+ .nlh = {
+ .nlmsg_len = sizeof(req),
+ .nlmsg_type = SOCK_DIAG_BY_FAMILY,
+ .nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST
+ },
+ .udr = {
+ .sdiag_family = AF_UNIX,
+ .udiag_ino = inode,
+ .udiag_states = -1,
+ .udiag_show = UDIAG_SHOW_NAME | UDIAG_SHOW_PEER,
+ }
+ };
+ struct iovec iov = {
+ .iov_base = &req,
+ .iov_len = sizeof(req)
+ };
+ struct msghdr msg = {
+ .msg_name = (void*)&nladdr,
+ .msg_namelen = sizeof(nladdr),
+ .msg_iov = &iov,
+ .msg_iovlen = 1
+ };
+
+ for (;;) {
+ if (sendmsg(fd, &msg, 0) < 0) {
+ if (errno == EINTR)
+ continue;
+ return false;
+ }
+ return true;
+ }
+}
+
+static bool
+unix_parse_response(const void *data, int data_len, const unsigned long inode)
+{
+ const struct unix_diag_msg *diag_msg = data;
+ int rta_len = data_len - NLMSG_LENGTH(sizeof(*diag_msg));
+ struct rtattr *attr;
+ size_t path_len = 0;
+ char path[UNIX_PATH_MAX + 1] = { [0] = '\0' };
+
+ uint32_t peer = 0;
+ if (diag_msg->udiag_ino != inode)
+ return false;
+ if (diag_msg->udiag_family != AF_UNIX)
+ return false;
+
+ attr = (struct rtattr*) (diag_msg +1);
+ while (RTA_OK(attr, rta_len)) {
+ switch (attr->rta_type) {
+ case UNIX_DIAG_NAME:
+ if (!path_len) {
+ path_len = RTA_PAYLOAD(attr);
+ if (path_len > UNIX_PATH_MAX)
+ path_len = UNIX_PATH_MAX;
+ memcpy(path, RTA_DATA(attr), path_len);
+ break;
+ }
+ case UNIX_DIAG_PEER:
+ if (RTA_PAYLOAD(attr) >= 4)
+ peer = *(uint32_t *)RTA_DATA(attr);
+ break;
+ }
+ attr = RTA_NEXT(attr, rta_len);
+ }
+
+ /* prints the getting information with following format:
+ * "UNIX:[" SELF_INODE [ "->" PEER_INODE ][ "," SOCKET_FILE ] "]" */
+ if (peer || path_len) {
+ tprintf("UNIX:[%lu", inode);
+ if (peer)
+ tprintf("->%u", peer);
+ if (path_len) {
+ if (path[0] == '\0')
+ tprintf(",@\"%s\"", path + 1);
+ else
+ tprintf(",\"%s\"", path);
+ }
+ tprints("]");
+ return true;
+ }
+ else
+ return false;
+}
+
+static bool
+unix_print(int fd, const unsigned long inode)
+{
+ return unix_send_query(fd, inode)
+ && receive_responses(fd, inode, unix_parse_response);
}
+
/* Given an inode number of a socket, print out the details
* of the ip address and port. */
bool
@@ -153,7 +267,7 @@ print_sockaddr_by_inode(const unsigned long inode, const char *proto_name)
int fd;
bool r = false;
- fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_INET_DIAG);
+ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
if (fd < 0)
return false;
@@ -166,6 +280,8 @@ print_sockaddr_by_inode(const unsigned long inode, const char *proto_name)
r = inet_print(fd, AF_INET6, IPPROTO_TCP, inode);
else if (strcmp(proto_name, "UDPv6") == 0)
r = inet_print(fd, AF_INET6, IPPROTO_UDP, inode);
+ else if (strcmp(proto_name, "UNIX") == 0)
+ r = unix_print(fd, inode);
} else {
const int families[] = {AF_INET, AF_INET6};
const int protocols[] = {IPPROTO_TCP, IPPROTO_UDP};
--
1.9.3
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