svn commit: r281959 - head/usr.bin/whois

[Xin LI]

Author: delphij
Date: Sat Apr 25 00:51:44 2015
New Revision: 281959
URL: https://svnweb.freebsd.org/changeset/base/281959

Log:
  Try alternate addresses more agressively.
  
  Attempt to connect to alternate addresses if the connect doesn't
  succeed in 180ms, and cut wait time between connection attempts
  in half for each additional, if no connection was established.
  
  Take the first connection to succeed and close the others.
  
  This makes whois more responsive when e.g. IPv6 service took long
  time or fail to respond.
  
  PR:		158125
  Submitted by:	Mark Andrews <marka isc org> (with changes from me)
  MFC after:	2 weeks

Modified:
  head/usr.bin/whois/whois.c

Modified: head/usr.bin/whois/whois.c
==============================================================================
--- head/usr.bin/whois/whois.c	Sat Apr 25 00:36:43 2015	(r281958)
+++ head/usr.bin/whois/whois.c	Sat Apr 25 00:51:44 2015	(r281959)
@@ -1,4 +1,4 @@
-/*
+/*-
  * Copyright (c) 1980, 1993
  *	The Regents of the University of California.  All rights reserved.
  *
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/poll.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <ctype.h>
@@ -55,6 +56,8 @@ __FBSDID("$FreeBSD$");
 #include <string.h>
 #include <sysexits.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
 
 #define	ABUSEHOST	"whois.abuse.net"
 #define	NICHOST		"whois.crsnic.net"
@@ -280,21 +283,136 @@ whois(const char *query, const char *hos
 	FILE *fp;
 	struct addrinfo *hostres, *res;
 	char *buf, *host, *nhost, *p;
-	int i, s;
+	int i, j, s = -1, count;
 	size_t c, len;
+	struct pollfd *fds;
+	int timeout = 180;
 
-	s = -1;
 	hostres = gethostinfo(hostname, 1);
-	for (res = hostres; res; res = res->ai_next) {
-		s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+	for (res = hostres, count = 0; res; res = res->ai_next)
+		count++;
+
+	fds = calloc(count, sizeof(*fds));
+	if (fds == NULL)
+		err(EX_OSERR, "calloc()");
+
+	/*
+	 * Traverse the result list elements and make non-block
+	 * connection attempts.
+	 */
+	count = i = 0;
+	for (res = hostres; res != NULL; res = res->ai_next) {
+		s = socket(res->ai_family, res->ai_socktype | SOCK_NONBLOCK,
+		    res->ai_protocol);
 		if (s < 0)
 			continue;
-		if (connect(s, res->ai_addr, res->ai_addrlen) == 0)
-			break;
-		close(s);
+		if (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
+			if (errno == EINPROGRESS) {
+				/* Add the socket to poll list */
+				fds[i].fd = s;
+				fds[i].events = POLLERR | POLLHUP |
+						POLLIN | POLLOUT;
+				count++;
+				i++;
+			} else {
+				close(s);
+				s = -1;
+
+				/*
+				 * Poll only if we have something to poll,
+				 * otherwise just go ahead and try next
+				 * address
+				 */
+				if (count == 0)
+					continue;
+			}
+		} else
+			goto done;
+
+		/*
+		 * If we are at the last address, poll until a connection is
+		 * established or we failed all connection attempts.
+		 */
+		if (res->ai_next == NULL)
+			timeout = INFTIM;
+
+		/*
+		 * Poll the watched descriptors for successful connections:
+		 * if we still have more untried resolved addresses, poll only
+		 * once; otherwise, poll until all descriptors have errors,
+		 * which will be considered as ETIMEDOUT later.
+		 */
+		do {
+			int n;
+
+			n = poll(fds, i, timeout);
+			if (n == 0) {
+				/*
+				 * No event reported in time.  Try with a
+				 * smaller timeout (but cap at 2-3ms)
+				 * after a new host have been added.
+				 */
+				if (timeout >= 3)
+					timeout <<= 1;
+
+				break;
+			} else if (n < 0) {
+				/*
+				 * errno here can only be EINTR which we would want
+				 * to clean up and bail out.
+				 */
+				s = -1;
+				goto done;
+			}
+
+			/*
+			 * Check for the event(s) we have seen.
+			 */
+			for (j = 0; j < i; j++) {
+				if (fds[j].fd == -1 || fds[j].events == 0 ||
+				    fds[j].revents == 0)
+					continue;
+				if (fds[j].revents & ~(POLLIN | POLLOUT)) {
+					close(s);
+					fds[j].fd = -1;
+					fds[j].events = 0;
+					count--;
+					continue;
+				} else if (fds[j].revents & (POLLIN | POLLOUT)) {
+					/* Connect succeeded. */
+					s = fds[j].fd;
+
+					goto done;
+				}
+
+			}
+		} while (timeout == INFTIM && count != 0);
 	}
+
+	/* All attempts were failed */
+	s = -1;
+	if (count == 0)
+		errno = ETIMEDOUT;
+
+done:
+	/* Close all watched fds except the succeeded one */
+	for (j = 0; j < i; j++)
+		if (fds[j].fd != s && fds[j].fd != -1)
+			close(fds[j].fd);
+
+	if (s != -1) {
+                /* Restore default blocking behavior.  */
+                if ((flags = fcntl(s, F_GETFL)) != -1) {
+                        flags &= ~O_NONBLOCK;
+                        if (fcntl(s, F_SETFL, flags) == -1)
+                                err(EX_OSERR, "fcntl()");
+                } else
+			err(EX_OSERR, "fcntl()");
+        }
+
+	free(fds);
 	freeaddrinfo(hostres);
-	if (res == NULL)
+	if (s == -1)
 		err(EX_OSERR, "connect()");
 
 	fp = fdopen(s, "r+");