Append user-specified options from --dhcpv6-opt to DHCPv6 reply
messages. Options that exceed available buffer space are skipped
with a rate-limited warning.
Link: https://bugs.passt.top/show_bug.cgi?id=192
Signed-off-by: Anshu Kumari
---
v5:
- Replaced warn() with warn_ratelimit(now, ...)
v4:
- warn() instead of debug() when options don't fit in the reply.
- doc comment for dhcpv6_user_opts_fill() updated.
v3:
- rename dhcpv6_custom_opts_fill() to dhcpv6_user_opts_fill().
- Iterate directly over the pre-parsed binary dhcpv6_user_opts[]
array instead of re-parsing string values at reply time.
v2:
- Updated dhcpv6_custom_opts_fill() to parse str at reply time
using dhcpv6_opt_parse() instead of copying cached val/len.
---
dhcpv6.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
dhcpv6.h | 3 ++-
tap.c | 2 +-
3 files changed, 46 insertions(+), 3 deletions(-)
diff --git a/dhcpv6.c b/dhcpv6.c
index a98f1a9c..9bafa99e 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -891,17 +891,58 @@ static size_t dhcpv6_client_fqdn_fill(const struct iov_tail *data,
return offset + sizeof(struct opt_hdr) + opt_len;
}
+/**
+ * dhcpv6_user_opts_fill() - Append user-specified options to reply
+ * @buf: Response message buffer
+ * @offset: Current offset in buffer
+ * @now: Current timestamp
+ *
+ * Return: offset after appended user options
+ */
+static size_t dhcpv6_user_opts_fill(char *buf, size_t offset,
+ const struct timespec *now)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(dhcpv6_user_opts); i++) {
+ int vlen = dhcpv6_user_opts[i].len;
+ struct opt_hdr *hdr;
+
+ if (!vlen)
+ continue;
+
+ if (offset + sizeof(struct opt_hdr) + vlen > OPT_MAX_SIZE) {
+ warn_ratelimit(now,
+ "DHCPv6: option %u doesn't fit, skipping",
+ i);
+ continue;
+ }
+
+ hdr = (struct opt_hdr *)(buf + offset);
+ hdr->t = htons(i);
+ hdr->l = htons(vlen);
+ offset += sizeof(struct opt_hdr);
+
+ memcpy(buf + offset, dhcpv6_user_opts[i].val, vlen);
+ offset += vlen;
+ }
+
+ return offset;
+}
+
/**
* dhcpv6() - Check if this is a DHCPv6 message, reply as needed
* @c: Execution context
* @data: Single packet starting from UDP header
* @saddr: Source IPv6 address of original message
* @daddr: Destination IPv6 address of original message
+ * @now: Current timestamp
*
* Return: 0 if it's not a DHCPv6 message, 1 if handled, -1 on failure
*/
int dhcpv6(struct ctx *c, struct iov_tail *data,
- const struct in6_addr *saddr, const struct in6_addr *daddr)
+ const struct in6_addr *saddr, const struct in6_addr *daddr,
+ const struct timespec *now)
{
const struct opt_server_id *server_id = NULL;
const struct opt_hdr *client_id = NULL;
@@ -1029,6 +1070,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data,
sizeof(struct opt_hdr) + ntohs(client_id->l);
n = dhcpv6_dns_fill(c, (char *)&resp, n);
n = dhcpv6_client_fqdn_fill(data, c, (char *)&resp, n);
+ n = dhcpv6_user_opts_fill((char *)&resp, n, now);
resp.hdr.xid = mh->xid;
diff --git a/dhcpv6.h b/dhcpv6.h
index 6cefd15b..00cf51af 100644
--- a/dhcpv6.h
+++ b/dhcpv6.h
@@ -7,7 +7,8 @@
#define DHCPV6_H
int dhcpv6(struct ctx *c, struct iov_tail *data,
- const struct in6_addr *saddr, const struct in6_addr *daddr);
+ const struct in6_addr *saddr, const struct in6_addr *daddr,
+ const struct timespec *now);
void dhcpv6_init(const struct ctx *c);
void dhcpv6_set_opt(uint16_t code, const char *val_str);
const char *dhcpv6_opt_to_str(uint16_t code, char *buf, size_t buf_len,
diff --git a/tap.c b/tap.c
index dfa66c71..0a9938de 100644
--- a/tap.c
+++ b/tap.c
@@ -1041,7 +1041,7 @@ resume:
if (proto == IPPROTO_UDP) {
struct iov_tail uh_data = data;
- if (dhcpv6(c, &uh_data, saddr, daddr))
+ if (dhcpv6(c, &uh_data, saddr, daddr, now))
continue;
}
--
2.55.0