Only bits 1 and 2 are used in the DHCP overload option, so when we encounter

the option set the last bit as well to ensure servername and bootfile are
only checked once as their check unsets bits 1 and 2.

Thanks to Tobias Stoeckmann.

diff --git a/dhcp.c b/dhcp.c
index fefb549d740c6b1dc38b078a1e15491ff7a4293e..13a5759272475c05ab5162adce95b3a2a493be36 100644 (file)
--- a/dhcp.c
+++ b/dhcp.c
@@ -203,9 +203,12 @@ get_option(struct dhcpcd_ctx *ctx,
                                goto exit;
                        break;
                case DHO_OPTIONSOVERLOADED:
-                       /* Ensure we only get this option once */
+                       /* Ensure we only get this option once by setting
+                        * the last bit as well as the value.
+                        * This is valid because only the first two bits
+                        * actually mean anything in RFC2132 Section 9.3 */
                        if (!overl)
-                               overl = p[1];
+                               overl = 0x80 | p[1];
                        break;
                }
                l = *p++;