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-rw-r--r--src/dhcpv4.c18
-rw-r--r--src/dhcpv4.h3
2 files changed, 16 insertions, 5 deletions
diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 7058b83..3fb5988 100644
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -35,6 +35,9 @@
#include "dhcpv4.h"
#include "dhcpv6.h"
+#define PACKET_SIZE(start, end) (((uint8_t *)end - (uint8_t *)start) < DHCPV4_MIN_PACKET_SIZE ? \
+ DHCPV4_MIN_PACKET_SIZE : (uint8_t *)end - (uint8_t *)start)
+
static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
static int setup_dhcpv4_addresses(struct interface *iface);
static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
@@ -429,15 +432,20 @@ static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
{
uint8_t *c = *cookie;
uint8_t *end = (uint8_t *)msg + sizeof(*msg);
+ bool tag_only = type == DHCPV4_OPT_PAD || type == DHCPV4_OPT_END;
+ int total_len = tag_only ? 1 : 2 + len;
- if (*cookie + 2 + len > end)
+ if (*cookie + total_len > end)
return;
+ *cookie += total_len;
*c++ = type;
+
+ if (tag_only)
+ return;
+
*c++ = len;
memcpy(c, data, len);
-
- *cookie = c + len;
}
static void dhcpv4_fr_send(struct dhcp_assignment *a)
@@ -518,7 +526,7 @@ static void dhcpv4_fr_send(struct dhcp_assignment *a)
dest.sin_port = htons(DHCPV4_CLIENT_PORT);
dest.sin_addr.s_addr = a->addr;
- if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, sizeof(fr_msg),
+ if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, PACKET_SIZE(&fr_msg, cookie),
MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0)
syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg),
odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
@@ -861,7 +869,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
}
- if (sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
+ if (sendto(sock, &reply, PACKET_SIZE(&reply, cookie), MSG_DONTWAIT,
(struct sockaddr*)&dest, sizeof(dest)) < 0)
syslog(LOG_ERR, "Failed to send %s to %s - %s: %m",
dhcpv4_msg_to_string(msg),
diff --git a/src/dhcpv4.h b/src/dhcpv4.h
index 96bd068..505346f 100644
--- a/src/dhcpv4.h
+++ b/src/dhcpv4.h
@@ -19,6 +19,8 @@
#define DHCPV4_FLAG_BROADCAST 0x8000
+#define DHCPV4_MIN_PACKET_SIZE 300
+
enum dhcpv4_op {
DHCPV4_BOOTREQUEST = 1,
DHCPV4_BOOTREPLY = 2
@@ -37,6 +39,7 @@ enum dhcpv4_msg {
};
enum dhcpv4_opt {
+ DHCPV4_OPT_PAD = 0,
DHCPV4_OPT_NETMASK = 1,
DHCPV4_OPT_ROUTER = 3,
DHCPV4_OPT_DNSSERVER = 6,