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Hi!
If there are many networking interfaces in a machine, 4096 bytes buffer
namely for RTM_GETLINK query can be too small. ATM the calls just
fail if MSG_TRUNC is seen, while the following patch handles
that case by resending the request (with increased seq number) and
doubling the buffer size for receive.
Although I don't have that many interfaces myself (IP aliases don't
count), I have tested it by decreasing the starting buf_size
from 4096 to 256, so that it needs enlargement 2 times even on
my box.
2005-06-13 Jakub Jelinek <jakub@redhat.com>
* sysdeps/unix/sysv/linux/netlinkaccess.h (__netlink_sendreq,
__netlink_receive): Remove prototypes.
(__netlink_request): New prototype.
* sysdeps/unix/sysv/linux/ifaddrs.c: Include <alloca.h> and
<stdint.h>.
(__netlink_sendreq): Make static.
(__netlink_receive): Rename to...
(__netlink_request): ... this. Add type argument, call
__netlink_sendreq. If MSG_TRUNC is set after recvmsg, retry
with a bigger buffer. Don't record buffers that contain no
messages we are expecting.
(getifaddrs): Use __netlink_request instead of __netlink_sendreq
and __netlink_receive pairs. Formatting.
* sysdeps/unix/sysv/linux/if_index.c (if_nameindex_netlink): Use
__netlink_request instead of __netlink_sendreq and __netlink_receive
pair.
--- libc/sysdeps/unix/sysv/linux/netlinkaccess.h.jj 2004-06-30 09:40:24.000000000 +0200
+++ libc/sysdeps/unix/sysv/linux/netlinkaccess.h 2005-06-11 11:26:16.000000000 +0200
@@ -1,4 +1,4 @@
-/* Copyright (C) 2004 Free Software Foundation, Inc.
+/* Copyright (C) 2004, 2005 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -55,8 +55,7 @@ extern int __no_netlink_support attribut
extern int __netlink_open (struct netlink_handle *h);
extern void __netlink_close (struct netlink_handle *h);
extern void __netlink_free_handle (struct netlink_handle *h);
-extern int __netlink_sendreq (struct netlink_handle *h, int type);
-extern int __netlink_receive (struct netlink_handle *h);
+extern int __netlink_request (struct netlink_handle *h, int type);
#endif /* netlinkaccess.h */
--- libc/sysdeps/unix/sysv/linux/if_index.c.jj 2004-07-12 17:50:25.000000000 +0200
+++ libc/sysdeps/unix/sysv/linux/if_index.c 2005-06-11 12:36:48.000000000 +0200
@@ -1,4 +1,5 @@
-/* Copyright (C) 1997,98,99,2000,2002,2003,2004 Free Software Foundation, Inc.
+/* Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005
+ Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -188,12 +189,8 @@ if_nameindex_netlink (void)
/* Tell the kernel that we wish to get a list of all
- active interfaces. */
- if (__netlink_sendreq (&nh, RTM_GETLINK) < 0)
- goto exit_close;
-
- /* Collect all data for every interface. */
- if (__netlink_receive (&nh) < 0)
+ active interfaces. Collect all data for every interface. */
+ if (__netlink_request (&nh, RTM_GETLINK) < 0)
goto exit_free;
/* Count the interfaces. */
@@ -290,7 +287,6 @@ if_nameindex_netlink (void)
exit_free:
__netlink_free_handle (&nh);
- exit_close:
__netlink_close (&nh);
return idx;
--- libc/sysdeps/unix/sysv/linux/ifaddrs.c.jj 2005-06-10 00:53:27.000000000 +0200
+++ libc/sysdeps/unix/sysv/linux/ifaddrs.c 2005-06-11 14:00:51.000000000 +0200
@@ -1,5 +1,5 @@
/* getifaddrs -- get names and addresses of all network interfaces
- Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -17,6 +17,7 @@
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
+#include <alloca.h>
#include <assert.h>
#include <errno.h>
#include <ifaddrs.h>
@@ -24,6 +25,7 @@
#include <netinet/in.h>
#include <netpacket/packet.h>
#include <stdbool.h>
+#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
@@ -84,7 +86,7 @@ __netlink_free_handle (struct netlink_ha
}
-int
+static int
__netlink_sendreq (struct netlink_handle *h, int type)
{
struct
@@ -114,15 +116,37 @@ __netlink_sendreq (struct netlink_handle
int
-__netlink_receive (struct netlink_handle *h)
+__netlink_request (struct netlink_handle *h, int type)
{
- struct netlink_res *nlm_next;
- char buf[4096];
- struct iovec iov = { buf, sizeof (buf) };
+ struct netlink_res *nlm_next, **new_nlm_list;
+ static size_t buf_size = 4096;
+ char *buf;
struct sockaddr_nl nladdr;
struct nlmsghdr *nlmh;
- int read_len;
+ ssize_t read_len;
bool done = false;
+ bool use_malloc = false;
+
+ if (__netlink_sendreq (h, type) < 0)
+ return -1;
+
+ if (! __libc_use_alloca (buf_size))
+ {
+ buf = malloc (buf_size);
+ if (buf != NULL)
+ use_malloc = true;
+ else
+ buf = alloca (buf_size);
+ }
+ else
+ buf = alloca (buf_size);
+
+ struct iovec iov = { buf, buf_size };
+
+ if (h->nlm_list != NULL)
+ new_nlm_list = &h->end_ptr->next;
+ else
+ new_nlm_list = &h->nlm_list;
while (! done)
{
@@ -136,33 +160,66 @@ __netlink_receive (struct netlink_handle
read_len = TEMP_FAILURE_RETRY (__recvmsg (h->fd, &msg, 0));
if (read_len < 0)
- return -1;
+ goto out_fail;
- if (msg.msg_flags & MSG_TRUNC)
- return -1;
+ if (nladdr.nl_pid != 0)
+ continue;
- nlm_next = (struct netlink_res *) malloc (sizeof (struct netlink_res)
- + read_len);
- if (nlm_next == NULL)
- return -1;
- nlm_next->next = NULL;
- nlm_next->nlh = memcpy (nlm_next + 1, buf, read_len);
- nlm_next->size = read_len;
- nlm_next->seq = h->seq;
- if (h->nlm_list == NULL)
- h->nlm_list = nlm_next;
- else
- h->end_ptr->next = nlm_next;
- h->end_ptr = nlm_next;
+ if (__builtin_expect (msg.msg_flags & MSG_TRUNC, 0))
+ {
+ if (buf_size >= SIZE_MAX / 2)
+ goto out_fail;
+ nlm_next = *new_nlm_list;
+ while (nlm_next != NULL)
+ {
+ struct netlink_res *tmpptr;
+
+ tmpptr = nlm_next->next;
+ free (nlm_next);
+ nlm_next = tmpptr;
+ }
+ *new_nlm_list = NULL;
+
+ buf_size *= 2;
+ if (use_malloc)
+ {
+ char *new_buf = realloc (buf, buf_size);
+ if (new_buf == NULL)
+ goto out_fail;
+ new_buf = buf;
+ }
+ else
+ {
+ buf = malloc (buf_size);
+ if (buf == NULL)
+ goto out_fail;
+ use_malloc = true;
+ }
+
+ iov.iov_base = buf;
+ iov.iov_len = buf_size;
+
+ /* Increase sequence number, so that we can distinguish
+ between old and new request messages. */
+ h->seq++;
+
+ if (__netlink_sendreq (h, type) < 0)
+ goto out_fail;
+
+ continue;
+ }
+
+ size_t count = 0, remaining_len = read_len;
for (nlmh = (struct nlmsghdr *) buf;
- NLMSG_OK (nlmh, (size_t) read_len);
- nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
+ NLMSG_OK (nlmh, remaining_len);
+ nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, remaining_len))
{
- if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != h->pid
+ if ((pid_t) nlmh->nlmsg_pid != h->pid
|| nlmh->nlmsg_seq != h->seq)
continue;
+ ++count;
if (nlmh->nlmsg_type == NLMSG_DONE)
{
/* We found the end, leave the loop. */
@@ -176,11 +233,38 @@ __netlink_receive (struct netlink_handle
errno = EIO;
else
errno = -nlerr->error;
- return -1;
+ goto out_fail;
}
}
+
+ /* If there was nothing with the expected nlmsg_pid and nlmsg_seq,
+ there is no point to record it. */
+ if (count == 0)
+ continue;
+
+ nlm_next = (struct netlink_res *) malloc (sizeof (struct netlink_res)
+ + read_len);
+ if (nlm_next == NULL)
+ goto out_fail;
+ nlm_next->next = NULL;
+ nlm_next->nlh = memcpy (nlm_next + 1, buf, read_len);
+ nlm_next->size = read_len;
+ nlm_next->seq = h->seq;
+ if (h->nlm_list == NULL)
+ h->nlm_list = nlm_next;
+ else
+ h->end_ptr->next = nlm_next;
+ h->end_ptr = nlm_next;
}
+
+ if (use_malloc)
+ free (buf);
return 0;
+
+out_fail:
+ if (use_malloc)
+ free (buf);
+ return -1;
}
@@ -268,7 +352,7 @@ getifaddrs (struct ifaddrs **ifap)
unsigned int i, newlink, newaddr, newaddr_idx;
int *map_newlink_data;
size_t ifa_data_size = 0; /* Size to allocate for all ifa_data. */
- char *ifa_data_ptr; /* Pointer to the unused part of memory for
+ char *ifa_data_ptr; /* Pointer to the unused part of memory for
ifa_data. */
int result = 0;
@@ -288,28 +372,20 @@ getifaddrs (struct ifaddrs **ifap)
#endif
/* Tell the kernel that we wish to get a list of all
- active interfaces. */
- if (__netlink_sendreq (&nh, RTM_GETLINK) < 0)
- {
- result = -1;
- goto exit_close;
- }
- /* Collect all data for every interface. */
- if (__netlink_receive (&nh) < 0)
+ active interfaces, collect all data for every interface. */
+ if (__netlink_request (&nh, RTM_GETLINK) < 0)
{
result = -1;
goto exit_free;
}
-
/* Now ask the kernel for all addresses which are assigned
- to an interface. Since we store the addresses after the
- interfaces in the list, we will later always find the
- interface before the corresponding addresses. */
+ to an interface and collect all data for every interface.
+ Since we store the addresses after the interfaces in the
+ list, we will later always find the interface before the
+ corresponding addresses. */
++nh.seq;
- if (__netlink_sendreq (&nh, RTM_GETADDR) < 0
- /* Collect all data for every interface. */
- || __netlink_receive (&nh) < 0)
+ if (__netlink_request (&nh, RTM_GETADDR) < 0)
{
result = -1;
goto exit_free;
@@ -327,7 +403,7 @@ getifaddrs (struct ifaddrs **ifap)
continue;
/* Walk through all entries we got from the kernel and look, which
- message type they contain. */
+ message type they contain. */
for (nlh = nlp->nlh; NLMSG_OK (nlh, size); nlh = NLMSG_NEXT (nlh, size))
{
/* Check if the message is what we want. */
@@ -423,7 +499,7 @@ getifaddrs (struct ifaddrs **ifap)
/* Interfaces are stored in the first "newlink" entries
of our list, starting in the order as we got from the
kernel. */
- ifa_index = map_newlink (ifim->ifi_index - 1, ifas,
+ ifa_index = map_newlink (ifim->ifi_index - 1, ifas,
map_newlink_data, newlink);
ifas[ifa_index].ifa.ifa_flags = ifim->ifi_flags;
@@ -767,8 +843,6 @@ getifaddrs (struct ifaddrs **ifap)
exit_free:
__netlink_free_handle (&nh);
-
- exit_close:
__netlink_close (&nh);
return result;
Jakub
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