Changeset bbb7ffe in mainline

Timestamp:

2022-06-24T09:40:05Z (3 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

master, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

b7155d7

Parents:

52214a2

git-author:

Jiri Svoboda <jiri@…> (2022-07-23 19:39:46)

git-committer:

Jiri Svoboda <jiri@…> (2022-06-24 09:40:05)

Message:

Randomize DHCP XID, cosmetic flag fix

Set XID to a random 32-bit number, instead of 42.
DHCP flags is technically 16-bit field, although this has no effect on
the function.

Location:

uspace/srv/net/dhcp

Files:

• dhcp.c (modified) (11 diffs)
• dhcp_std.h (modified) (2 diffs)

uspace/srv/net/dhcp/dhcp.c

@@ -1 +1 @@
 /*
- * Copyright (c) 2021 Jiri Svoboda
+ * Copyright (c) 2022 Jiri Svoboda
  * All rights reserved.
  *
@@ -47 +47 @@
 #include <io/log.h>
 #include <loc.h>
+#include <rndgen.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -95 +96 @@
         /** DNS server */
         inet_addr_t dns_server;
+        /** Transaction ID */
+        uint32_t xid;
 } dhcp_offer_t;
 
@@ -114 +117 @@
         /** Last received offer */
         dhcp_offer_t offer;
+        /** Random number generator */
+        rndgen_t *rndgen;
 } dhcp_link_t;
 
@@ -154 +159 @@
         dhcp_hdr_t *hdr = (dhcp_hdr_t *)msgbuf;
         uint8_t *opt = msgbuf + sizeof(dhcp_hdr_t);
+        uint32_t xid;
+        errno_t rc;
+
+        rc = rndgen_uint32(dlink->rndgen, &xid);
+        if (rc != EOK)
+                return rc;
 
         memset(msgbuf, 0, MAX_MSG_SIZE);
@@ -159 +170 @@
         hdr->htype = 1; /* AHRD_ETHERNET */
         hdr->hlen = ETH_ADDR_SIZE;
-        hdr->xid = host2uint32_t_be(42);
-        hdr->flags = flag_broadcast;
+        hdr->xid = host2uint32_t_be(xid);
+        hdr->flags = host2uint16_t_be(flag_broadcast);
 
         eth_addr_encode(&dlink->link_info.mac_addr, hdr->chaddr);
@@ -168 +179 @@
         opt[1] = 1;
         opt[2] = msg_dhcpdiscover;
+
         opt[3] = opt_end;
 
@@ -183 +195 @@
         hdr->htype = 1; /* AHRD_ETHERNET */
         hdr->hlen = 6;
-        hdr->xid = host2uint32_t_be(42);
-        hdr->flags = flag_broadcast;
+        hdr->xid = host2uint32_t_be(offer->xid);
+        hdr->flags = host2uint16_t_be(flag_broadcast);
         eth_addr_encode(&dlink->link_info.mac_addr, hdr->chaddr);
         hdr->opt_magic = host2uint32_t_be(dhcp_opt_magic);
@@ -257 +269 @@
 
         inet_naddr_set(yiaddr.addr, 0, &offer->oaddr);
+        offer->xid = uint32_t_be2host(hdr->xid);
 
         msgb = (uint8_t *)msg;
@@ -456 +469 @@
                 return ENOMEM;
 
+        rc = rndgen_create(&dlink->rndgen);
+        if (rc != EOK)
+                goto error;
+
         dlink->link_id = link_id;
         dlink->timeout = fibril_timer_create(NULL);
@@ -493 +510 @@
         return EOK;
 error:
+        if (dlink != NULL && dlink->rndgen != NULL)
+                rndgen_destroy(dlink->rndgen);
         if (dlink != NULL && dlink->timeout != NULL)
                 fibril_timer_destroy(dlink->timeout);

uspace/srv/net/dhcp/dhcp_std.h

@@ -1 +1 @@
 /*
- * Copyright (c) 2013 Jiri Svoboda
+ * Copyright (c) 2022 Jiri Svoboda
  * All rights reserved.
  *
@@ -87 +87 @@
 /** Values for dhcp_hdr_t.flags */
 enum dhcp_flags {
-        flag_broadcast = 0x80
+        flag_broadcast = 0x8000
 };