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simplify and document lookup_next_rule()

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This commit is contained in:
Luigi Rizzo 2009-12-17 17:27:12 +00:00
parent a8092021a0
commit 60ab046a41
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=200634
1 changed files with 21 additions and 42 deletions
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63
sys/netinet/ipfw/ip_fw2.c
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@ -630,50 +630,27 @@ send_reject(struct ip_fw_args *args, int code, int ip_len, struct ip *ip)
}
/**
* Given an ip_fw *, lookup_next_rule will return a pointer
* to the next rule, which can be either the jump
* target (for skipto instructions) or the next one in the list (in
* all other cases including a missing jump target).
* The result is also written in the "next_rule" field of the rule.
* Backward jumps are not allowed, so we start the search from the
* rule following the current one.
* Return the pointer to the skipto target.
*
* IMPORTANT: this should only be called on SKIPTO rules, and the
* jump target is taken from the 'rulenum' argument, which may come
* from the rule itself (direct skipto) or not (tablearg)
*
* The function never returns NULL: if the requested rule is not
* present, it returns the next rule in the chain.
* As a side effect, the rule pointer is also set so next time
* the jump will not require a scan of the list.
* This also happens in case of a bogus argument > 65535
*/
static struct ip_fw *
lookup_next_rule(struct ip_fw *me, u_int32_t tablearg)
lookup_next_rule(struct ip_fw *me, uint32_t rulenum)
{
struct ip_fw *rule = NULL;
ipfw_insn *cmd;
u_int16_t rulenum;
struct ip_fw *rule;
/* look for action, in case it is a skipto */
cmd = ACTION_PTR(me);
if (cmd->opcode == O_LOG)
cmd += F_LEN(cmd);
if (cmd->opcode == O_ALTQ)
cmd += F_LEN(cmd);
if (cmd->opcode == O_TAG)
cmd += F_LEN(cmd);
if (cmd->opcode == O_SKIPTO ) {
if (tablearg != 0) {
rulenum = (u_int16_t)tablearg;
} else {
rulenum = cmd->arg1;
}
for (rule = me->next; rule ; rule = rule->next) {
if (rule->rulenum >= rulenum) {
break;
}
}
for (rule = me->next; rule ; rule = rule->next) {
if (rule->rulenum >= rulenum)
break;
}
if (rule == NULL) /* failure or not a skipto */
rule = me->next;
me->next_rule = rule;
rule = me->next ? me->next : me;
return rule;
}
@ -2013,13 +1990,15 @@ do { \
l = 0; /* exit inner loop */
break;
}
/* handle skipto */
/* skipto: */
if (cmd->arg1 == IP_FW_TABLEARG) {
f = lookup_next_rule(f, tablearg);
} else {
if (f->next_rule == NULL)
lookup_next_rule(f, 0);
f = f->next_rule;
f = lookup_next_rule(f, tablearg);
} else { /* direct skipto */
/* update f->next_rule if not set */
if (f->next_rule == NULL)
f->next_rule =
lookup_next_rule(f, cmd->arg1);
f = f->next_rule;
}
/*
* Skip disabled rules, and
@ -2032,7 +2011,7 @@ do { \
if (f) { /* found a valid rule */
l = f->cmd_len;
cmd = f->cmd;
} else {
} else { /* should not happen */
l = 0; /* exit inner loop */
}
match = 1;