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.
diff --git a/socketutils.c b/socketutils.c
new file mode 100644
index 0000000..d5cddf0
--- /dev/null
+++ b/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;
+}