On Tue 15 Nov 2005, Paul Slootman wrote:
> Hmm, hold off on any action here, it looks like something may still need
> to be tweaked.
I had missed one place where /proc/net/dev is read, namely
agent/mibgroup/if-mib/data_access/interface_linux.c .
Attached is the revised patch.
Paul Slootman
diff -ru net-snmp-5.2.1.2/agent/mibgroup/if-mib/data_access/interface_linux.c
net-snmp-5.2.1.2.fix/agent/mibgroup/if-mib/data_access/interface_linux.c
--- net-snmp-5.2.1.2/agent/mibgroup/if-mib/data_access/interface_linux.c
2004-10-18 05:49:50.000000000 +0200
+++ net-snmp-5.2.1.2.fix/agent/mibgroup/if-mib/data_access/interface_linux.c
2005-11-15 14:45:33.000000000 +0100
@@ -59,6 +59,7 @@
u_int load_flags)
{
FILE *devin;
+ char proc_net_dev_buf[51200];
char line[256];
/*
* scanline_2_2:
@@ -107,6 +108,11 @@
snmp_log(LOG_ERR, "cannot open /proc/net/dev ...\n");
return -2;
}
+ /*
+ * default stdio buffer of 10k is not enough with > 85 interfaces,
+ * the contents change between reads and this causes data format errors.
+ */
+ setvbuf(devin, proc_net_dev_buf, _IOFBF, sizeof(proc_net_dev_buf));
/*
* create socket for ioctls
diff -ru net-snmp-5.2.1.2/agent/mibgroup/mibII/ifTable.c
net-snmp-5.2.1.2.fix/agent/mibgroup/mibII/ifTable.c
--- net-snmp-5.2.1.2/agent/mibgroup/mibII/ifTable.c 2004-07-07
19:41:15.000000000 +0200
+++ net-snmp-5.2.1.2.fix/agent/mibgroup/mibII/ifTable.c 2005-11-15
13:16:16.000000000 +0100
@@ -738,6 +738,7 @@
ifTable_load(netsnmp_cache * cache, void *vmagic)
{
FILE *devin;
+ char proc_net_dev_buf[51200];
char line[256];
const char *scan_line_2_2 =
"%llu %llu %llu %llu %*llu %*llu %*llu %*llu %llu %llu %llu %llu %*llu
%llu";
@@ -768,6 +769,11 @@
snmp_log(LOG_ERR, "snmpd: cannot open /proc/net/dev ...\n");
return -1;
}
+ /*
+ * default stdio buffer of 10k is not enough with > 85 interfaces,
+ * the contents change between reads and this causes data format errors.
+ */
+ setvbuf(devin, proc_net_dev_buf, _IOFBF, sizeof(proc_net_dev_buf));
/*
* Read the first two lines of the file, containing the header
@@ -821,7 +827,8 @@
}
if ((scan_line_to_use == scan_line_2_2) && ((stats - line) < 6)) {
snmp_log(LOG_ERR,
- "/proc/net/dev data format error, line ==|%s|", line);
+ "/proc/net/dev data format error; line ==|%s|", line);
+ continue;
}
*stats = 0;
entry = ifTable_ifentry_get_by_name(cache, ifstart, 1);
diff -ru net-snmp-5.2.1.2/agent/mibgroup/mibII/interfaces.c
net-snmp-5.2.1.2.fix/agent/mibgroup/mibII/interfaces.c
--- net-snmp-5.2.1.2/agent/mibgroup/mibII/interfaces.c 2005-01-03
16:51:32.000000000 +0100
+++ net-snmp-5.2.1.2.fix/agent/mibgroup/mibII/interfaces.c 2005-11-15
14:55:59.000000000 +0100
@@ -1383,6 +1383,7 @@
Interface_Scan_Init(void)
{
#ifdef linux
+ char proc_net_dev_buf[51200];
char line[256], ifname_buf[64], *ifname, *ptr;
struct ifreq ifrq;
struct ifnet **ifnetaddr_ptr;
@@ -1468,6 +1469,11 @@
snmp_log(LOG_ERR, "cannot open /proc/net/dev - continuing...\n");
return; /** exit (1); **/
}
+ /*
+ * default stdio buffer of 10k is not enough with > 85 interfaces,
+ * the contents change between reads and this causes data format errors.
+ */
+ setvbuf(devin, proc_net_dev_buf, _IOFBF, sizeof(proc_net_dev_buf));
i = 0;
@@ -1507,7 +1513,8 @@
}
if ((scan_line_to_use == scan_line_2_2) && ((stats - line) < 6)) {
snmp_log(LOG_ERR,
- "/proc/net/dev data format error, line ==|%s|", line);
+ "/proc/net/dev data format error; line ==|%s|", line);
+ continue;
}
*stats = 0;
diff -ru net-snmp-5.2.1.2/debian/changelog net-snmp-5.2.1.2.fix/debian/changelog
--- net-snmp-5.2.1.2/debian/changelog 2005-11-15 13:40:41.000000000 +0100
+++ net-snmp-5.2.1.2.fix/debian/changelog 2005-11-15 13:17:43.000000000
+0100
@@ -1,3 +1,11 @@
+net-snmp (5.2.1.2-4.fix) unstable; urgency=low
+
+ * use large buffer for /proc/net/dev, to prevent data format errors when the
+ data is more than 10k and changes between reads (>85 interfaces, 2.4
+ kernel)
+
+ -- Paul Slootman <[EMAIL PROTECTED]> Tue, 15 Nov 2005 13:16:31 +0100
+
net-snmp (5.2.1.2-4) unstable; urgency=low
* Version builddep on libssl-dev and rebuild, for openssl transition
