[iptables PATCH 1/2] libxtables: Register only the highest revision extension

[Phil Sutter <phil@nwl.cc>]

When fully registering extensions, ignore all consecutive ones with same
name and family value. Since commit b3ac87038f4e4 ("libxtables: Make
sure extensions register in revision order"), one may safely assume the
list of pending extensions has highest revision numbers first. Since
iptables is only interested in the highest revision the kernel supports,
registration and compatibility checks may be skipped once the first
matching extension in pending list has validated.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 libxtables/xtables.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libxtables/xtables.c b/libxtables/xtables.c
index 50fd6a44b0100..b34d62acf6015 100644
--- a/libxtables/xtables.c
+++ b/libxtables/xtables.c
@@ -697,6 +697,7 @@ xtables_find_match(const char *name, enum xtables_tryload tryload,
 	struct xtables_match **dptr;
 	struct xtables_match *ptr;
 	const char *icmp6 = "icmp6";
+	bool found = false;
 
 	if (strlen(name) >= XT_EXTENSION_MAXNAMELEN)
 		xtables_error(PARAMETER_PROBLEM,
@@ -715,7 +716,9 @@ xtables_find_match(const char *name, enum xtables_tryload tryload,
 		if (extension_cmp(name, (*dptr)->name, (*dptr)->family)) {
 			ptr = *dptr;
 			*dptr = (*dptr)->next;
-			if (xtables_fully_register_pending_match(ptr, prev)) {
+			if (!found &&
+			    xtables_fully_register_pending_match(ptr, prev)) {
+				found = true;
 				prev = ptr;
 				continue;
 			} else if (prev) {
@@ -817,6 +820,7 @@ xtables_find_target(const char *name, enum xtables_tryload tryload)
 	struct xtables_target *prev = NULL;
 	struct xtables_target **dptr;
 	struct xtables_target *ptr;
+	bool found = false;
 
 	/* Standard target? */
 	if (strcmp(name, "") == 0
@@ -831,7 +835,9 @@ xtables_find_target(const char *name, enum xtables_tryload tryload)
 		if (extension_cmp(name, (*dptr)->name, (*dptr)->family)) {
 			ptr = *dptr;
 			*dptr = (*dptr)->next;
-			if (xtables_fully_register_pending_target(ptr, prev)) {
+			if (!found &&
+			    xtables_fully_register_pending_target(ptr, prev)) {
+				found = true;
 				prev = ptr;
 				continue;
 			} else if (prev) {
-- 
2.34.1