Add -yy option: print ip and port associated with socket descriptors

When two ore more -y options are given, print local and remote ip:port
pairs associated with socket descriptors.  This implementation uses
NETLINK_INET_DIAG for sockaddr lookup; it's based on the patch
prepared by Zubin Mithra as a part of his GSoC 2014 strace project.

* Makefile.am (strace_SOURCES): Add socketutils.c
(EXTRA_DIST): Add linux/inet_diag.h and linux/sock_diag.h.
* defs.h (print_sockaddr_by_inode): New prototype.
* linux/inet_diag.h: New file.
* linux/sock_diag.h: Likewise.
* socketutils.c: Likewise.
* strace.1: Document -yy option.
* strace.c (usage): Likewise.
* util.c (printfd): Use print_sockaddr_by_inode.

Makefile.am

@@ -46,6 +46,7 @@ strace_SOURCES =	\
 	scsi.c		\
 	signal.c	\
 	sock.c		\
+	socketutils.c	\
 	strace.c	\
 	stream.c	\
 	syscall.c	\
@@ -122,6 +123,7 @@ EXTRA_DIST =				\
 	linux/ia64/ioctlent.h.in	\
 	linux/ia64/signalent.h		\
 	linux/ia64/syscallent.h		\
+	linux/inet_diag.h		\
 	linux/inotify.h			\
 	linux/ioctlent-filter.awk	\
 	linux/ioctlent.h.in		\
@@ -165,6 +167,7 @@ EXTRA_DIST =				\
 	linux/sh64/ioctlent.h.in	\
 	linux/sh64/syscallent.h		\
 	linux/signalent.h		\
+	linux/sock_diag.h		\
 	linux/sparc/dummy2.h		\
 	linux/sparc/errnoent.h		\
 	linux/sparc/errnoent1.h		\

defs.h

@@ -694,6 +694,7 @@ extern void printsiginfo(siginfo_t *, int);
 extern void printsiginfo_at(struct tcb *tcp, long addr);
 #endif
 extern void printfd(struct tcb *, int);
+extern bool print_sockaddr_by_inode(const unsigned long);
 extern void print_dirfd(struct tcb *, int);
 extern void printsock(struct tcb *, long, int);
 extern void print_sock_optmgmt(struct tcb *, long, int);

linux/inet_diag.h

@@ -0,0 +1,38 @@
+#define TCPDIAG_GETSOCK 18
+#define DCCPDIAG_GETSOCK 19
+
+/* Socket identity */
+struct inet_diag_sockid {
+	uint16_t idiag_sport;
+	uint16_t idiag_dport;
+	uint32_t idiag_src[4];
+	uint32_t idiag_dst[4];
+	uint32_t idiag_if;
+	uint32_t idiag_cookie[2];
+};
+
+/* Request structure */
+struct inet_diag_req_v2 {
+	uint8_t sdiag_family;
+	uint8_t sdiag_protocol;
+	uint8_t idiag_ext;
+	uint8_t pad;
+	uint32_t idiag_states;
+	struct inet_diag_sockid id;
+};
+
+/* Info structure */
+struct inet_diag_msg {
+	uint8_t idiag_family;
+	uint8_t idiag_state;
+	uint8_t idiag_timer;
+	uint8_t idiag_retrans;
+
+	struct inet_diag_sockid id;
+
+	uint32_t idiag_expires;
+	uint32_t idiag_rqueue;
+	uint32_t idiag_wqueue;
+	uint32_t idiag_uid;
+	uint32_t idiag_inode;
+};

linux/sock_diag.h

@@ -0,0 +1,6 @@
+#define SOCK_DIAG_BY_FAMILY 20
+
+struct sock_diag_req {
+	uint8_t	sdiag_family;
+	uint8_t	sdiag_protocol;
+};

socketutils.c

@@ -0,0 +1,172 @@
+#include "defs.h"
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <linux/netlink.h>
+#include <linux/sock_diag.h>
+#include <linux/inet_diag.h>
+
+static bool
+send_query(const int fd, const int family, const int proto)
+{
+	struct sockaddr_nl nladdr;
+	struct {
+		struct nlmsghdr nlh;
+		struct inet_diag_req_v2 idr;
+	} req;
+	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
+	};
+
+	memset(&nladdr, 0, sizeof(nladdr));
+	nladdr.nl_family = AF_NETLINK;
+
+	memset(&req, 0, sizeof(req));
+	req.nlh.nlmsg_len = sizeof(req);
+	req.nlh.nlmsg_type = SOCK_DIAG_BY_FAMILY;
+	req.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
+	req.idr.sdiag_family = family;
+	req.idr.sdiag_protocol = proto;
+	req.idr.idiag_states = -1;
+
+	for (;;) {
+		if (sendmsg(fd, &msg, 0) < 0) {
+			if (errno == EINTR)
+				continue;
+			return false;
+		}
+		return true;
+	}
+}
+
+static bool
+parse_response(const struct inet_diag_msg *diag_msg, const unsigned long inode)
+{
+	static const char zero_addr[sizeof(struct in6_addr)];
+	socklen_t addr_size, text_size;
+
+	if (diag_msg->idiag_inode != inode)
+		return false;
+
+	switch(diag_msg->idiag_family) {
+		case AF_INET:
+			addr_size = sizeof(struct in_addr);
+			text_size = INET_ADDRSTRLEN;
+			break;
+		case AF_INET6:
+			addr_size = sizeof(struct in6_addr);
+			text_size = INET6_ADDRSTRLEN;
+			break;
+		default:
+			return false;
+	}
+
+	char src_buf[text_size];
+
+	if (!inet_ntop(diag_msg->idiag_family, diag_msg->id.idiag_src,
+		       src_buf, text_size))
+		return false;
+
+	if (diag_msg->id.idiag_dport ||
+	    memcmp(zero_addr, diag_msg->id.idiag_dst, addr_size)) {
+		char dst_buf[text_size];
+
+		if (!inet_ntop(diag_msg->idiag_family, diag_msg->id.idiag_dst,
+			       dst_buf, text_size))
+			return false;
+
+		tprintf("%s:%u->%s:%u",
+			src_buf, ntohs(diag_msg->id.idiag_sport),
+			dst_buf, ntohs(diag_msg->id.idiag_dport));
+	} else {
+		tprintf("%s:%u", src_buf, ntohs(diag_msg->id.idiag_sport));
+	}
+
+	return true;
+}
+
+static bool
+receive_responses(const int fd, const unsigned long inode)
+{
+	static char buf[8192];
+	struct sockaddr_nl nladdr;
+	struct iovec iov = {
+		.iov_base = buf,
+		.iov_len = sizeof(buf)
+	};
+
+	memset(&nladdr, 0, sizeof(nladdr));
+	nladdr.nl_family = AF_NETLINK;
+
+	for (;;) {
+		ssize_t ret;
+		struct nlmsghdr *h;
+		struct msghdr msg = {
+			.msg_name = (void*)&nladdr,
+			.msg_namelen = sizeof(nladdr),
+			.msg_iov = &iov,
+			.msg_iovlen = 1,
+			.msg_control = NULL,
+			.msg_controllen = 0,
+			.msg_flags = 0
+		};
+
+		ret = recvmsg(fd, &msg, 0);
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			return false;
+		}
+		if (!ret)
+			return false;
+		for (h = (struct nlmsghdr*)buf;
+		     NLMSG_OK(h, ret);
+		     h = NLMSG_NEXT(h, ret)) {
+			switch (h->nlmsg_type) {
+				case NLMSG_DONE:
+				case NLMSG_ERROR:
+					return false;
+			}
+			if (parse_response(NLMSG_DATA(h), inode))
+				return true;
+		}
+	}
+}
+
+/* Given an inode number of a socket, print out the details
+ * of the ip address and port. */
+bool
+print_sockaddr_by_inode(const unsigned long inode)
+{
+	const int families[] = {AF_INET, AF_INET6};
+	const int protocols[] = {IPPROTO_TCP, IPPROTO_UDP};
+	const size_t flen = ARRAY_SIZE(families);
+	const size_t plen = ARRAY_SIZE(protocols);
+	size_t fi, pi;
+	int fd;
+
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_INET_DIAG);
+	if (fd < 0)
+		return false;
+
+	for (fi = 0; fi < flen; ++fi) {
+		for (pi = 0; pi < plen; ++pi) {
+			if (!send_query(fd, families[fi], protocols[pi]))
+				continue;
+			if (receive_responses(fd, inode)) {
+				close(fd);
+				return true;
+			}
+		}
+	}
+
+	close(fd);
+	return false;
+}

strace.1

@@ -321,6 +321,9 @@ Print all strings in hexadecimal string format.
 .B \-y
 Print paths associated with file descriptor arguments.
 .TP
+.B \-yy
+Print ip:port pairs associated with socket file descriptors.
+.TP
 .BI "\-a " column
 Align return values in a specific column (default column 40).
 .TP

strace.c

@@ -216,6 +216,7 @@ usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
 -v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\
 -x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\
 -y -- print paths associated with file descriptor arguments\n\
+-yy -- print ip:port pairs associated with socket file descriptors\n\
 -h -- print help message, -V -- print version\n\
 -a column -- alignment COLUMN for printing syscall results (default %d)\n\
 -b execve -- detach on this syscall\n\

util.c

@@ -404,10 +404,24 @@ void
 printfd(struct tcb *tcp, int fd)
 {
 	char path[PATH_MAX + 1];
+	if (show_fd_path && getfdpath(tcp, fd, path, sizeof(path)) >= 0) {
+		static const char socket_prefix[] = "socket:[";
+		const size_t socket_prefix_len = sizeof(socket_prefix) - 1;
+		size_t path_len;
 
-	if (show_fd_path && getfdpath(tcp, fd, path, sizeof(path)) >= 0)
-		tprintf("%d<%s>", fd, path);
-	else
+		if (show_fd_path > 1 &&
+		    strncmp(path, socket_prefix, socket_prefix_len) == 0 &&
+		    path[(path_len = strlen(path)) - 1] == ']') {
+			unsigned long inodenr;
+			inodenr = strtoul(path + socket_prefix_len, NULL, 10);
+			tprintf("%d<", fd);
+			if (!print_sockaddr_by_inode(inodenr))
+				tprints(path);
+			tprints(">");
+		} else {
+			tprintf("%d<%s>", fd, path);
+		}
+	} else
 		tprintf("%d", fd);
 }