On Fri, Jul 17, 2026 at 11:26:38PM +0530, Anshu Kumari wrote:
Change fill_one() to accept a buffer pointer and capacity instead of a struct msg pointer. This is a pure refactor with no behavior change, preparing for option overload support where fill_one() will also write into the file and sname fields.
Link: https://bugs.passt.top/show_bug.cgi?id=192 Signed-off-by: Anshu Kumari
Reviewed-by: David Gibson
--- v5: - Restore debug messages for skipped options in fill() - Add /* code and length of option */ comment in size check - Use buf + *offset instead of &buf[*offset] for memcpy
v3: - Restored removed comments: "If we don't have space to write the option, then just skip" and "Move to option".
v2: - Renamed parameter cap → size. --- dhcp.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/dhcp.c b/dhcp.c index c3c7422..bb72b72 100644 --- a/dhcp.c +++ b/dhcp.c @@ -131,28 +131,29 @@ struct msg { } __attribute__((__packed__));
/** - * fill_one() - Fill a single option in message - * @m: Message to fill + * fill_one() - Fill a single option into a buffer + * @buf: Buffer to write option + * @size: Usable size of @buf (excluding end marker) * @o: Option number - * @offset: Current offset within options field, updated on insertion + * @offset: Current offset within @buf, updated on insertion * - * Return: false if m has space to write the option, true otherwise + * Return: false if @buf has space to write the option, true otherwise */ -static bool fill_one(struct msg *m, int o, int *offset) +static bool fill_one(uint8_t *buf, size_t size, int o, int *offset) { size_t slen = opts[o].slen;
/* If we don't have space to write the option, then just skip */ - if (*offset + 2 /* code and length of option */ + slen > OPT_MAX) + if (*offset + 2 /* code and length of option */ + slen > size) return true;
- m->o[*offset] = o; - m->o[*offset + 1] = slen; + buf[*offset] = o; + buf[*offset + 1] = slen;
/* Move to option */ *offset += 2;
- memcpy(&m->o[*offset], opts[o].s, slen); + memcpy(buf + *offset, opts[o].s, slen);
opts[o].sent = 1; *offset += slen; @@ -177,19 +178,19 @@ static int fill(struct msg *m) * Put it there explicitly, unless requested via option 55. */ if (opts[55].clen > 0 && !memchr(opts[55].c, 53, opts[55].clen)) - if (fill_one(m, 53, &offset)) - debug("DHCP: skipping option 53"); + if (fill_one(m->o, OPT_MAX, 53, &offset)) + debug("DHCP: skipping option 53");
for (i = 0; i < opts[55].clen; i++) { o = opts[55].c[i]; if (opts[o].slen != -1) - if (fill_one(m, o, &offset)) + if (fill_one(m->o, OPT_MAX, o, &offset)) debug("DHCP: skipping option %i", o); }
for (o = 0; o < 255; o++) { if (opts[o].slen != -1 && !opts[o].sent) - if (fill_one(m, o, &offset)) + if (fill_one(m->o, OPT_MAX, o, &offset)) debug("DHCP: skipping option %i", o); }
-- 2.54.0
-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson