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From: Paolo Pisati <piso@FreeBSD.org>
To: Perforce Change Reviews <perforce@freebsd.org>
Cc: 
Subject: PERFORCE change 111341 for review
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http://perforce.freebsd.org/chv.cgi?CH=111341

Change 111341 by piso@piso_newluxor on 2006/12/09 21:01:37

	Introduce LibAliasInLocked() & LibAliasOutLocked() for the
	PKT_ALIAS_REVERSE case: using these functions we avoid a dangerous 
	drop and reacquire of the lock around a call to 
	LibAliasIn*()/LibAliasOut*().
	
	Suggested by: glebius

Affected files ...

.. //depot/projects/soc2005/libalias/sys/netinet/libalias/alias.c#26 edit

Differences ...

==== //depot/projects/soc2005/libalias/sys/netinet/libalias/alias.c#26 (text+ko) ====

@@ -1211,20 +1211,35 @@
 	LIBALIAS_UNLOCK(la);
 }
 
+/* Local prototypes */
+static int
+LibAliasOutLocked(struct libalias *la, char *ptr,
+		  int maxpacketsize);
+static int
+LibAliasInLocked(struct libalias *la, char *ptr,
+		  int maxpacketsize);
 
 int
 LibAliasIn(struct libalias *la, char *ptr, int maxpacketsize)
 {
+	int res;
+
+	LIBALIAS_LOCK(la);
+	res = LibAliasInLocked(la, ptr, maxpacketsize);
+	LIBALIAS_LOCK(la);
+	return (res);
+}
+
+static int
+LibAliasInLocked(struct libalias *la, char *ptr, int maxpacketsize)
+{
 	struct in_addr alias_addr;
 	struct ip *pip;
 	int iresult;
-
-	LIBALIAS_LOCK(la);
+	
 	if (la->packetAliasMode & PKT_ALIAS_REVERSE) {
 		la->packetAliasMode &= ~PKT_ALIAS_REVERSE;
-		LIBALIAS_UNLOCK(la);
-		iresult = LibAliasOut(la, ptr, maxpacketsize);
-		LIBALIAS_LOCK(la);
+		iresult = LibAliasOutLocked(la, ptr, maxpacketsize);
 		la->packetAliasMode |= PKT_ALIAS_REVERSE;
 		goto getout;
 	}
@@ -1293,7 +1308,6 @@
 	}
 
 getout:
-	LIBALIAS_UNLOCK(la);
 	return (iresult);
 }
 
@@ -1314,31 +1328,31 @@
 #define UNREG_ADDR_C_UPPER 0xc0a8ffff
 
 int
-LibAliasOut(struct libalias *la, char *ptr,	/* valid IP packet */
-    int maxpacketsize		/* How much the packet data may grow (FTP
-				 * and IRC inline changes) */
-)
+LibAliasOut(struct libalias *la, char *ptr, int maxpacketsize)
 {
-	return (LibAliasOutTry(la, ptr, maxpacketsize, 1));
+	int res;
+
+	LIBALIAS_LOCK(la);
+	res = LibAliasOutLocked(la, ptr, maxpacketsize);
+	LIBALIAS_UNLOCK(la);
+	return (res);
 }
 
-int
-LibAliasOutTry(struct libalias *la, char *ptr,	/* valid IP packet */
-    int maxpacketsize,		/* How much the packet data may grow (FTP
+static int
+LibAliasOutLocked(struct libalias *la, char *ptr,	/* valid IP packet */
+    int maxpacketsize		/* How much the packet data may grow (FTP
 				 * and IRC inline changes) */
-    int create			/* Create new entries ? */
 )
 {
 	int iresult;
+	int create;			/* Create new entries ? */
 	struct in_addr addr_save;
 	struct ip *pip;
 
-	LIBALIAS_LOCK(la);
+	create = 1;
 	if (la->packetAliasMode & PKT_ALIAS_REVERSE) {
 		la->packetAliasMode &= ~PKT_ALIAS_REVERSE;
-		LIBALIAS_UNLOCK(la);
-		iresult = LibAliasIn(la, ptr, maxpacketsize);
-		LIBALIAS_LOCK(la);
+		iresult = LibAliasInLocked(la, ptr, maxpacketsize);
 		la->packetAliasMode |= PKT_ALIAS_REVERSE;
 		goto getout;
 	}
@@ -1414,7 +1428,6 @@
 
 	SetDefaultAliasAddress(la, addr_save);
 getout:
-	LIBALIAS_UNLOCK(la);
 	return (iresult);
 }