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Cache network interface information
Whenever getaddrinfo needed network interface information it used the netlink interface to read the information every single time. The problem is that this information can change at any time. The patch implements monitoring of the network interfaces through nscd. If no change is detected the previously read information can be reused (which is the norm). This timestamp information is also made available to other processes using the shared memory segment between nscd and those processes.
This commit is contained in:
Ulrich Drepper
@ -1,5 +1,5 @@
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/* Determine protocol families for which interfaces exist. Linux version.
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Copyright (C) 2003, 2006, 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
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Copyright (C) 2003, 2006-2008, 2010, 2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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@ -33,6 +33,9 @@
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#include <not-cancel.h>
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#include <kernel-features.h>
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#include <bits/libc-lock.h>
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#include <atomic.h>
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#include <nscd/nscd-client.h>
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#ifndef IFA_F_HOMEADDRESS
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@ -43,9 +46,42 @@
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#endif
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static int
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make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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struct in6addrinfo **in6ai, size_t *in6ailen)
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struct cached_data
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{
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uint32_t timestamp;
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uint32_t usecnt;
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bool seen_ipv4;
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bool seen_ipv6;
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size_t in6ailen;
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struct in6addrinfo in6ai[0];
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};
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static struct cached_data noai6ai_cached =
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{
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.usecnt = 3, /* Make sure we never try to delete this entry. */
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.in6ailen = 0
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};
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static struct cached_data *cache;
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__libc_lock_define_initialized (static, lock);
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#ifdef IS_IN_nscd
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static uint32_t nl_timestamp;
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uint32_t
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__bump_nl_timestamp (void)
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{
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if (atomic_increment_val (&nl_timestamp) == 0)
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atomic_increment (&nl_timestamp);
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return nl_timestamp;
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}
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#endif
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static struct cached_data *
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make_request (int fd, pid_t pid)
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{
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struct req
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{
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@ -99,9 +135,6 @@ make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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sizeof (nladdr))) < 0)
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goto out_fail;
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*seen_ipv4 = false;
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*seen_ipv6 = false;
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bool done = false;
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struct in6ailist
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{
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@ -109,6 +142,8 @@ make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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struct in6ailist *next;
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} *in6ailist = NULL;
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size_t in6ailistlen = 0;
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bool seen_ipv4 = false;
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bool seen_ipv6 = false;
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do
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{
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@ -172,12 +207,12 @@ make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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{
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if (*(const in_addr_t *) address
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!= htonl (INADDR_LOOPBACK))
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*seen_ipv4 = true;
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seen_ipv4 = true;
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}
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else
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{
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if (!IN6_IS_ADDR_LOOPBACK (address))
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*seen_ipv6 = true;
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seen_ipv6 = true;
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}
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}
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@ -211,30 +246,46 @@ make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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}
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while (! done);
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if (*seen_ipv6 && in6ailist != NULL)
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struct cached_data *result;
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if (seen_ipv6 && in6ailist != NULL)
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{
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*in6ai = malloc (in6ailistlen * sizeof (**in6ai));
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if (*in6ai == NULL)
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result = malloc (sizeof (*result)
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+ in6ailistlen * sizeof (struct in6addrinfo));
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if (result == NULL)
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goto out_fail;
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*in6ailen = in6ailistlen;
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#ifdef IS_IN_nscd
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result->timestamp = nl_timestamp;
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#else
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result->timestamp = __nscd_get_nl_timestamp ();
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#endif
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result->usecnt = 2;
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result->seen_ipv4 = seen_ipv4;
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result->seen_ipv6 = true;
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result->in6ailen = in6ailistlen;
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do
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{
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(*in6ai)[--in6ailistlen] = in6ailist->info;
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result->in6ai[--in6ailistlen] = in6ailist->info;
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in6ailist = in6ailist->next;
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}
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while (in6ailist != NULL);
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}
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else
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{
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noai6ai_cached.seen_ipv4 = seen_ipv4;
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noai6ai_cached.seen_ipv6 = seen_ipv6;
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result = &noai6ai_cached;
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}
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if (use_malloc)
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free (buf);
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return 0;
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return result;
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out_fail:
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if (use_malloc)
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free (buf);
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return -1;
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return NULL;
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}
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@ -258,28 +309,65 @@ __check_pf (bool *seen_ipv4, bool *seen_ipv6,
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if (! __no_netlink_support)
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{
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int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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struct cached_data *olddata = NULL;
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struct cached_data *data = NULL;
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if (__builtin_expect (fd >= 0, 1))
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__libc_lock_lock (lock);
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#ifdef IS_IN_nscd
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# define cache_valid() nl_timestamp != 0 && cache->timestamp == nl_timestamp
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#else
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# define cache_valid() \
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({ uint32_t val = __nscd_get_nl_timestamp (); \
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val != 0 && cache->timestamp == val; })
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#endif
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if (cache != NULL && cache_valid ())
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{
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struct sockaddr_nl nladdr;
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memset (&nladdr, '\0', sizeof (nladdr));
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nladdr.nl_family = AF_NETLINK;
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data = cache;
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atomic_increment (&cache->usecnt);
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}
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else
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{
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int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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socklen_t addr_len = sizeof (nladdr);
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if (__builtin_expect (fd >= 0, 1))
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{
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struct sockaddr_nl nladdr;
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memset (&nladdr, '\0', sizeof (nladdr));
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nladdr.nl_family = AF_NETLINK;
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bool success
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= (__bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
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&& __getsockname (fd, (struct sockaddr *) &nladdr,
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&addr_len) == 0
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&& make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6,
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in6ai, in6ailen) == 0);
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socklen_t addr_len = sizeof (nladdr);
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close_not_cancel_no_status (fd);
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if(__bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
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&& __getsockname (fd, (struct sockaddr *) &nladdr,
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&addr_len) == 0)
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data = make_request (fd, nladdr.nl_pid);
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if (success)
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/* It worked. */
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return;
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close_not_cancel_no_status (fd);
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}
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if (data != NULL)
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{
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olddata = cache;
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cache = data;
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}
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}
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__libc_lock_unlock (lock);
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if (data != NULL)
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{
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/* It worked. */
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*seen_ipv4 = data->seen_ipv4;
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*seen_ipv6 = data->seen_ipv6;
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*in6ailen = data->in6ailen;
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*in6ai = data->in6ai;
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if (olddata != NULL && olddata->usecnt > 0
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&& atomic_add_zero (&olddata->usecnt, -1))
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free (olddata);
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return;
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}
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#if __ASSUME_NETLINK_SUPPORT == 0
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@ -318,3 +406,26 @@ __check_pf (bool *seen_ipv4, bool *seen_ipv6,
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(void) freeifaddrs (ifa);
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#endif
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}
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void
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__free_in6ai (struct in6addrinfo *ai)
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{
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if (ai != NULL)
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{
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struct cached_data *data =
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(struct cached_data *) ((char *) ai
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- offsetof (struct cached_data, in6ai));
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if (atomic_add_zero (&data->usecnt, -1))
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{
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__libc_lock_lock (lock);
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if (data->usecnt == 0)
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/* Still unused. */
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free (data);
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__libc_lock_unlock (lock);
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}
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}
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}
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