diff options
author | Stefan Tomanek <stefan.tomanek@wertarbyte.de> | 2011-03-08 22:42:51 +0100 |
---|---|---|
committer | Jan Engelhardt <jengelh@medozas.de> | 2011-03-08 23:12:05 +0100 |
commit | d59b9db031abee37a9aa9776662dd15370faabf4 (patch) | |
tree | 47481f2b5f1afbc122f494beca1375de661c1160 /libiptc/libiptc.c | |
parent | 9cc4f24e72f87ca191c2e723e7cd293f6477481c (diff) |
iptables: add -C to check for existing rules
It is often useful to check whether a specific rule is already present
in a chain without actually modifying the iptables config.
Services like fail2ban usually employ techniques like grepping through
the output of "iptables -L" which is quite error prone.
This patch adds a new operation -C to the iptables command which
mostly works like -D; it can detect and indicate the existence of the
specified rule by modifying the exit code. The new operation
TC_CHECK_ENTRY uses the same code as the -D operation, whose functions
got a dry-run parameter appended.
Signed-off-by: Stefan Tomanek <stefan.tomanek@wertarbyte.de>
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Diffstat (limited to 'libiptc/libiptc.c')
-rw-r--r-- | libiptc/libiptc.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c index 7a9c7428..d3b1c517 100644 --- a/libiptc/libiptc.c +++ b/libiptc/libiptc.c @@ -31,6 +31,7 @@ */ #include <sys/types.h> #include <sys/socket.h> +#include <stdbool.h> #include <xtables.h> #include "linux_list.h" @@ -1956,12 +1957,11 @@ is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask); -/* Delete the first rule in `chain' which matches `fw'. */ -int -TC_DELETE_ENTRY(const IPT_CHAINLABEL chain, - const STRUCT_ENTRY *origfw, - unsigned char *matchmask, - struct xtc_handle *handle) + +/* find the first rule in `chain' which matches `fw' and remove it unless dry_run is set */ +static int delete_entry(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, + unsigned char *matchmask, struct xtc_handle *handle, + bool dry_run) { struct chain_head *c; struct rule_head *r, *i; @@ -2005,6 +2005,10 @@ TC_DELETE_ENTRY(const IPT_CHAINLABEL chain, if (!target_same(r, i, mask)) continue; + /* if we are just doing a dry run, we simply skip the rest */ + if (dry_run) + return 1; + /* If we are about to delete the rule that is the * current iterator, move rule iterator back. next * pointer will then point to real next node */ @@ -2027,6 +2031,20 @@ TC_DELETE_ENTRY(const IPT_CHAINLABEL chain, return 0; } +/* check whether a specified rule is present */ +int TC_CHECK_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, + unsigned char *matchmask, struct xtc_handle *handle) +{ + /* do a dry-run delete to find out whether a matching rule exists */ + return delete_entry(chain, origfw, matchmask, handle, true); +} + +/* Delete the first rule in `chain' which matches `fw'. */ +int TC_DELETE_ENTRY(const IPT_CHAINLABEL chain, const STRUCT_ENTRY *origfw, + unsigned char *matchmask, struct xtc_handle *handle) +{ + return delete_entry(chain, origfw, matchmask, handle, false); +} /* Delete the rule in position `rulenum' in `chain'. */ int |