From: Roy Marples <roy@marples.name>
Date: Wed, 15 Jan 2020 15:48:27 +0000 (+0000)
Subject: if: Fix hardware address randomisation
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c003fd8cff645876bd5b8116aee0170d0ed478ae;p=thirdparty%2Fdhcpcd.git

if: Fix hardware address randomisation

And copy back the actual length of it, not the whole buffer.
---

diff --git a/src/if.c b/src/if.c
index ff1a88bb..75776512 100644
--- a/src/if.c
+++ b/src/if.c
@@ -198,23 +198,20 @@ if_randomisemac(struct interface *ifp)
 			rp = (uint8_t *)&randnum;
 			rlen = sizeof(randnum);
 		}
-		if (bp == buf) {
-			/* First octet is special. We need to preserve
-			 * bit 8 (unicast/multicast) and set
-			 * bit 7 (locally administered address) */
-			*bp = *rp++ & 0xFC;
-			*bp++ |= 2;
-		} else
-			*bp++ = *rp++;
+		*bp++ = *rp++;
 		rlen--;
 	}
 
+	/* Unicast address and locally administered. */
+	buf[0] &= 0xFC;
+	buf[0] |= 0x02;
+
 	logdebugx("%s: hardware address randomised to %s",
 	    ifp->name,
 	    hwaddr_ntoa(buf, sizeof(buf), sbuf, sizeof(sbuf)));
 	retval = if_setmac(ifp, buf, ifp->hwlen);
 	if (retval == 0)
-		memcpy(ifp->hwaddr, buf, sizeof(ifp->hwaddr));
+		memcpy(ifp->hwaddr, buf, ifp->hwlen);
 	return retval;
 }