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
---
v4:
- Unchanged from v3.
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 | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/dhcp.c b/dhcp.c
index 1ff8cba..8e3ffd6 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 + 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;
@@ -177,20 +178,17 @@ 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");
+ fill_one(m->o, OPT_MAX, 53, &offset);
for (i = 0; i < opts[55].clen; i++) {
o = opts[55].c[i];
if (opts[o].slen != -1)
- if (fill_one(m, o, &offset))
- debug("DHCP: skipping option %i", o);
+ fill_one(m->o, OPT_MAX, o, &offset);
}
for (o = 0; o < 255; o++) {
if (opts[o].slen != -1 && !opts[o].sent)
- if (fill_one(m, o, &offset))
- debug("DHCP: skipping option %i", o);
+ fill_one(m->o, OPT_MAX, o, &offset);
}
m->o[offset++] = 255;
--
2.54.0