diff options
| -rw-r--r-- | dhcp.c | 79 | ||||
| -rw-r--r-- | forward.c | 2 |
2 files changed, 52 insertions, 29 deletions
@@ -66,20 +66,20 @@ get_dhcp_message_type (const struct dhcp *dhcp, const int optlen) } static in_addr_t -do_extract (struct dhcp *dhcp, const int optlen) +do_extract (struct dhcp *dhcp, int optlen) { uint8_t *p = (uint8_t *) (dhcp + 1); int i; in_addr_t ret = 0; - for (i = 0; i < optlen; ++i) + for (i = 0; i < optlen; ) { const uint8_t type = p[i]; const int room = optlen - i; if (type == DHCP_END) break; else if (type == DHCP_PAD) - ; + ++i; else if (type == DHCP_ROUTER) { if (room >= 2) @@ -87,23 +87,39 @@ do_extract (struct dhcp *dhcp, const int optlen) const int len = p[i+1]; /* get option length */ if (len <= (room-2)) { + /* get router IP address */ if (!ret && len >= 4 && (len & 3) == 0) { - memcpy (&ret, p+i+2, 4); /* get router IP address */ + memcpy (&ret, p+i+2, 4); ret = ntohl (ret); } - memset (p+i, DHCP_PAD, len+2); /* delete the router option by padding it out */ + { + /* delete the router option */ + uint8_t *dest = p + i; + const int owlen = len + 2; /* len of data to overwrite */ + uint8_t *src = dest + owlen; + uint8_t *end = p + optlen; + const int movlen = end - src; + if (movlen > 0) + memmove(dest, src, movlen); /* overwrite router option */ + memset(end - owlen, DHCP_PAD, owlen); /* pad tail */ + } } - i += (len + 1); /* advance to next option */ + else + break; } + else + break; } - else /* some other option */ + else /* some other option */ { if (room >= 2) { - const int len = p[i+1]; /* get option length */ - i += (len + 1); /* advance to next option */ + const int len = p[i+1]; /* get option length */ + i += (len + 2); /* advance to next option */ } + else + break; } } return ret; @@ -157,27 +173,34 @@ dhcp_extract_router_msg (struct buffer *ipbuf) && df->ip.protocol == OPENVPN_IPPROTO_UDP && df->udp.source == htons (BOOTPS_PORT) && df->udp.dest == htons (BOOTPC_PORT) - && df->dhcp.op == BOOTREPLY - && get_dhcp_message_type (&df->dhcp, optlen) == DHCPACK) + && df->dhcp.op == BOOTREPLY) { - /* get the router IP address while padding out all DHCP router options */ - const in_addr_t ret = do_extract (&df->dhcp, optlen); - - /* recompute the UDP checksum */ - df->udp.check = htons (udp_checksum ((uint8_t *) &df->udp, - sizeof (struct openvpn_udphdr) + sizeof (struct dhcp) + optlen, - (uint8_t *)&df->ip.saddr, - (uint8_t *)&df->ip.daddr)); - - if (ret) + const int message_type = get_dhcp_message_type (&df->dhcp, optlen); + if (message_type == DHCPACK || message_type == DHCPOFFER) { - struct gc_arena gc = gc_new (); - msg (D_ROUTE, "Extracted DHCP router address: %s", print_in_addr_t (ret, 0, &gc)); - gc_free (&gc); - } + /* get the router IP address while padding out all DHCP router options */ + const in_addr_t ret = do_extract (&df->dhcp, optlen); + + /* recompute the UDP checksum */ + df->udp.check = 0; + df->udp.check = htons (udp_checksum ((uint8_t *) &df->udp, + sizeof (struct openvpn_udphdr) + sizeof (struct dhcp) + optlen, + (uint8_t *)&df->ip.saddr, + (uint8_t *)&df->ip.daddr)); + + /* only return the extracted Router address if DHCPACK */ + if (message_type == DHCPACK) + { + if (ret) + { + struct gc_arena gc = gc_new (); + msg (D_ROUTE, "Extracted DHCP router address: %s", print_in_addr_t (ret, 0, &gc)); + gc_free (&gc); + } - return ret; + return ret; + } + } } - else - return 0; + return 0; } @@ -1011,7 +1011,7 @@ process_ipv4_header (struct context *c, unsigned int flags, struct buffer *buf) if (!c->options.passtos) flags &= ~PIPV4_PASSTOS; #endif - if (!c->options.route_gateway_via_dhcp || !route_list_vpn_gateway_needed (c->c1.route_list)) + if (!c->options.route_gateway_via_dhcp) flags &= ~PIPV4_EXTRACT_DHCP_ROUTER; if (buf->len > 0) |