From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by passt.top (Postfix, from userid 1000) id 8EE335A004C; Mon, 25 Nov 2024 16:28:12 +0100 (CET) From: Stefano Brivio To: passt-dev@passt.top Subject: [PATCH v3 1/3] dhcp: Use -1 as "missing option" length instead of 0 Date: Mon, 25 Nov 2024 16:28:10 +0100 Message-ID: <20241125152812.369553-2-sbrivio@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241125152812.369553-1-sbrivio@redhat.com> References: <20241125152812.369553-1-sbrivio@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: ECUWPLQRDKGAKW5WDBW6D4RYOUGFLW4B X-Message-ID-Hash: ECUWPLQRDKGAKW5WDBW6D4RYOUGFLW4B X-MailFrom: sbrivio@passt.top X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: We want to add support for option 80 (Rapid Commit, RFC 4039), whose length is 0. Signed-off-by: Stefano Brivio --- dhcp.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/dhcp.c b/dhcp.c index a06f143..57f69a5 100644 --- a/dhcp.c +++ b/dhcp.c @@ -36,9 +36,9 @@ /** * struct opt - DHCP option * @sent: Convenience flag, set while filling replies - * @slen: Length of option defined for server + * @slen: Length of option defined for server, -1 if not going to be sent * @s: Option payload from server - * @clen: Length of option received from client + * @clen: Length of option received from client, -1 if not received * @c: Option payload from client */ struct opt { @@ -68,6 +68,11 @@ static struct opt opts[255]; */ void dhcp_init(void) { + int i; + + for (i = 0; i < ARRAY_SIZE(opts); i++) + opts[i].slen = -1; + opts[1] = (struct opt) { 0, 4, { 0 }, 0, { 0 }, }; /* Mask */ opts[3] = (struct opt) { 0, 4, { 0 }, 0, { 0 }, }; /* Router */ opts[51] = (struct opt) { 0, 4, { 0xff, @@ -154,17 +159,17 @@ static int fill(struct msg *m) * option 53 at the beginning of the list. * Put it there explicitly, unless requested via option 55. */ - if (!memchr(opts[55].c, 53, opts[55].clen)) + if (opts[55].clen > 0 && !memchr(opts[55].c, 53, opts[55].clen)) fill_one(m, 53, &offset); for (i = 0; i < opts[55].clen; i++) { o = opts[55].c[i]; - if (opts[o].slen) + if (opts[o].slen != -1) fill_one(m, o, &offset); } for (o = 0; o < 255; o++) { - if (opts[o].slen && !opts[o].sent) + if (opts[o].slen != -1 && !opts[o].sent) fill_one(m, o, &offset); } @@ -264,6 +269,9 @@ static void opt_set_dns_search(const struct ctx *c, size_t max_len) ".\xc0"); } } + + if (!opts[119].slen) + opts[119].slen = -1; } /** @@ -313,6 +321,9 @@ int dhcp(const struct ctx *c, const struct pool *p) offset += offsetof(struct msg, o); + for (i = 0; i < ARRAY_SIZE(opts); i++) + opts[i].clen = -1; + while (opt_off + 2 < opt_len) { const uint8_t *olen, *val; uint8_t *type; @@ -334,8 +345,9 @@ int dhcp(const struct ctx *c, const struct pool *p) if (opts[53].c[0] == DHCPDISCOVER) { info("DHCP: offer to discover"); opts[53].s[0] = DHCPOFFER; - } else if (opts[53].c[0] == DHCPREQUEST || !opts[53].clen) { - info("%s: ack to request", opts[53].clen ? "DHCP" : "BOOTP"); + } else if (opts[53].c[0] == DHCPREQUEST || opts[53].clen <= 0) { + info("%s: ack to request", /* DHCP needs a valid message type */ + (opts[53].clen <= 0) ? "DHCP" : "BOOTP"); opts[53].s[0] = DHCPACK; } else { return -1; @@ -374,6 +386,8 @@ int dhcp(const struct ctx *c, const struct pool *p) ((struct in_addr *)opts[6].s)[i] = c->ip4.dns[i]; opts[6].slen += sizeof(uint32_t); } + if (!opts[6].slen) + opts[6].slen = -1; if (!c->no_dhcp_dns_search) opt_set_dns_search(c, sizeof(m->o)); -- 2.43.0