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netutils/dhcpc:Make DHCP xid random

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Signed-off-by: 田昕 <tianxin7@xiaomi.com>
This commit is contained in:
田昕 2022-09-05 22:18:20 +08:00 committed by Xiang Xiao
parent e031a82882
commit 37b77a78fa
1 changed files with 30 additions and 7 deletions
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37
netutils/dhcpc/dhcpc.c
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@ -44,6 +44,7 @@
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/random.h>
#include <inttypes.h>
#include <stdlib.h>
@ -131,6 +132,7 @@ struct dhcpc_state_s
{
FAR const char *interface;
int sockfd;
uint8_t xid[4];
struct in_addr ipaddr;
struct in_addr serverid;
struct dhcp_msg packet;
@ -145,11 +147,6 @@ struct dhcpc_state_s
* Private Data
****************************************************************************/
static const uint8_t xid[4] =
{
0xad, 0xde, 0x12, 0x23
};
static const uint8_t magic_cookie[4] =
{
99, 130, 83, 99
@ -234,7 +231,7 @@ static int dhcpc_sendmsg(FAR struct dhcpc_state_s *pdhcpc,
pdhcpc->packet.op = DHCP_REQUEST;
pdhcpc->packet.htype = DHCP_HTYPE_ETHERNET;
pdhcpc->packet.hlen = pdhcpc->maclen;
memcpy(pdhcpc->packet.xid, xid, 4);
memcpy(pdhcpc->packet.xid, pdhcpc->xid, 4);
memcpy(pdhcpc->packet.chaddr, pdhcpc->macaddr, pdhcpc->maclen);
memset(&pdhcpc->packet.chaddr[pdhcpc->maclen], 0, 16 - pdhcpc->maclen);
memcpy(pdhcpc->packet.options, magic_cookie, sizeof(magic_cookie));
@ -435,7 +432,7 @@ static uint8_t dhcpc_parsemsg(FAR struct dhcpc_state_s *pdhcpc, int buflen,
FAR struct dhcpc_state *presult)
{
if (buflen >= 44 && pdhcpc->packet.op == DHCP_REPLY &&
memcmp(pdhcpc->packet.xid, xid, sizeof(xid)) == 0 &&
memcmp(pdhcpc->packet.xid, pdhcpc->xid, 4) == 0 &&
memcmp(pdhcpc->packet.chaddr,
pdhcpc->macaddr, pdhcpc->maclen) == 0)
{
@ -506,6 +503,10 @@ FAR void *dhcpc_open(FAR const char *interface, FAR const void *macaddr,
struct sockaddr_in addr;
struct timeval tv;
int ret;
const uint8_t default_xid[4] =
{
0xad, 0xde, 0x12, 0x23
};
ninfo("MAC: %02x:%02x:%02x:%02x:%02x:%02x\n",
((uint8_t *)macaddr)[0], ((uint8_t *)macaddr)[1],
@ -517,6 +518,21 @@ FAR void *dhcpc_open(FAR const char *interface, FAR const void *macaddr,
pdhcpc = malloc(sizeof(struct dhcpc_state_s) + maclen - 1);
if (pdhcpc)
{
/* RFC2131: A DHCP client MUST choose 'xid's in such a
* way as to minimize the chance of using an 'xid' identical to one
* used by another client.
*/
ret = getrandom(pdhcpc->xid, 4, 0);
if (ret != 4)
{
ret = getrandom(pdhcpc->xid, 4, GRND_RANDOM);
if (ret != 4)
{
memcpy(pdhcpc->xid, default_xid, 4);
}
}
/* Initialize the allocated structure */
memset(pdhcpc, 0, sizeof(struct dhcpc_state_s));
@ -665,6 +681,13 @@ int dhcpc_request(FAR void *handle, FAR struct dhcpc_state *presult)
int retries;
int state;
/* RFC2131: For example, a client may choose a different,
* random initial 'xid' each time the client is rebooted, and
* subsequently use sequential 'xid's until the next reboot.
*/
pdhcpc->xid[3]++;
/* Save the currently assigned IP address (should be INADDR_ANY) */
oldaddr.s_addr = 0;