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udhcpd: untangle incredibly messy handling of DHCPREQUEST

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Also fixes attacks possible via DHCPDECLINE / DHCPRELEASE

function                                             old     new   delta
udhcpd_main                                         1846    1949    +103
send_renew                                           105     142     +37
send_NAK                                              61       -     -61
send_ACK                                             180       -    -180
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 2/0 up/down: 140/-241)         Total: -101 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2010-03-21 06:15:28 +01:00
parent 2e7aa92836
commit c7dc79e71d
9 changed files with 268 additions and 185 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
networking/udhcp/packet.c
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@ -21,7 +21,7 @@
void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
{
memset(packet, 0, sizeof(struct dhcp_packet));
memset(packet, 0, sizeof(*packet));
packet->op = BOOTREQUEST; /* if client to a server */
switch (type) {
case DHCPOFFER:
@ -29,10 +29,11 @@ void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type)
case DHCPNAK:
packet->op = BOOTREPLY; /* if server to client */
}
packet->htype = ETH_10MB;
packet->hlen = ETH_10MB_LEN;
packet->htype = 1; /* ethernet */
packet->hlen = 6;
packet->cookie = htonl(DHCP_MAGIC);
packet->options[0] = DHCP_END;
if (DHCP_END != 0)
packet->options[0] = DHCP_END;
add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
}
@ -228,6 +229,7 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
msg = "sendto";
ret_close:
close(fd);
/* FIXME: and if result >= 0 but != IP_UPD_DHCP_SIZE? */
if (result < 0) {
ret_msg:
bb_perror_msg(msg, "PACKET");
@ -280,6 +282,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
msg = "write";
ret_close:
close(fd);
/* FIXME: and if result >= 0 but != DHCP_SIZE? */
if (result < 0) {
ret_msg:
bb_perror_msg(msg, "UDP");