Date: Tue, 23 Sep 2008 13:37:52 +0400 From: Roman Kurakin <rik@inse.ru> To: Ganbold <ganbold@micom.mng.net> Cc: Roman Kurakin <rik@FreeBSD.org>, freebsd-ipfw@freebsd.org, rizzo@iet.unipi.it, julian@elischer.org Subject: Re: question related to /sbin/ipfw/ipfw2.c Message-ID: <48D8B8F0.8020900@localhost.inse.ru> In-Reply-To: <48D8A814.7030607@micom.mng.net>
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Ganbold wrote:
> Hi,
>
> What does following part of src/sbin/ipfw/ipfw2.c code?
> ...
> static void
> fill_ip(ipfw_insn_ip *cmd, char *av)
> {
> int len = 0;
> uint32_t *d = ((ipfw_insn_u32 *)cmd)->d;
>
> cmd->o.len &= ~F_LEN_MASK; /* zero len */
> -----------------------------------
> if (strncmp(av, "table(", 6) == 0) {
match the beginning of the "table(entry,value)"
> char *p = strchr(av + 6, ',');
find the ',' if any
>
> if (p)
> *p++ = '\0';
and replace it with '\0' eq "table(entry\0value)" so as a string it is
now "table(entry"
and make p point to 'value', eq p = 'value' now
> cmd->o.opcode = O_IP_DST_LOOKUP;
> cmd->o.arg1 = strtoul(av + 6, NULL, 0);
av+6 is the "entry" string
arg1=(unsigned long)entry
>
> if (p) {
if we have a 'value ' part
> cmd->o.len |= F_INSN_SIZE(ipfw_insn_u32);
> d[0] = strtoul(p, NULL, 0);
d[0] = (unsigned long)value
> } else
> cmd->o.len |= F_INSN_SIZE(ipfw_insn);
> return;
> }
Is that what you need?
rik
> -----------------------------------
>
> Specially, what does following code?
> ...
> cmd->o.opcode = O_IP_DST_LOOKUP;
> cmd->o.arg1 = strtoul(av + 6, NULL, 0);
> if (p) {
> cmd->o.len |= F_INSN_SIZE(ipfw_insn_u32);
> d[0] = strtoul(p, NULL, 0);
> } else
> cmd->o.len |= F_INSN_SIZE(ipfw_insn);
> ...
>
> thanks,
>
> Ganbold
>
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