static enum gnrc_ipv6_ext_demux_status _handle_rh(gnrc_pktsnip_t *current, gnrc_pktsnip_t *pkt) { gnrc_pktsnip_t *ipv6; ipv6_ext_t *ext = (ipv6_ext_t *) current->data; size_t current_offset; ipv6_hdr_t *hdr; /* check seg_left early to avoid duplicating the packet */ if (((ipv6_ext_rh_t *)ext)->seg_left == 0) { return GNRC_IPV6_EXT_OK; } /* We cannot use `gnrc_pktbuf_start_write` since it duplicates only the head. `ipv6_ext_rh_process` modifies the IPv6 header as well as the extension header */ current_offset = gnrc_pkt_len_upto(current->next, GNRC_NETTYPE_IPV6); if (pkt->users != 1) { if ((ipv6 = gnrc_pktbuf_duplicate_upto(pkt, GNRC_NETTYPE_IPV6)) == NULL) { DEBUG("ipv6: could not get a copy of pkt\n"); gnrc_pktbuf_release(pkt); return GNRC_IPV6_EXT_ERROR; } pkt = ipv6; hdr = ipv6->data; ext = (ipv6_ext_t *)(((uint8_t *)ipv6->data) + current_offset); } else { ipv6 = gnrc_pktsnip_search_type(pkt, GNRC_NETTYPE_IPV6); hdr = ipv6->data; } switch (ipv6_ext_rh_process(hdr, (ipv6_ext_rh_t *)ext)) { case EXT_RH_CODE_ERROR: /* TODO: send ICMPv6 error codes */ gnrc_pktbuf_release(pkt); return GNRC_IPV6_EXT_ERROR; case EXT_RH_CODE_FORWARD: /* forward packet */ if (!gnrc_netapi_dispatch_receive(GNRC_NETTYPE_IPV6, GNRC_NETREG_DEMUX_CTX_ALL, pkt)) { DEBUG("ipv6: could not dispatch packet to the ipv6 thread\n"); gnrc_pktbuf_release(pkt); } return GNRC_IPV6_EXT_FORWARDED; case EXT_RH_CODE_OK: /* this should not happen since we checked seg_left early */ gnrc_pktbuf_release(pkt); return GNRC_IPV6_EXT_ERROR; } return GNRC_IPV6_EXT_OK; }
static void _receive(gnrc_pktsnip_t *pkt) { kernel_pid_t iface = KERNEL_PID_UNDEF; gnrc_pktsnip_t *ipv6, *netif, *first_ext; ipv6_hdr_t *hdr; assert(pkt != NULL); netif = gnrc_pktsnip_search_type(pkt, GNRC_NETTYPE_NETIF); if (netif != NULL) { iface = ((gnrc_netif_hdr_t *)netif->data)->if_pid; #ifdef MODULE_NETSTATS_IPV6 assert(iface); netstats_t *stats = gnrc_ipv6_netif_get_stats(iface); stats->rx_count++; stats->rx_bytes += (gnrc_pkt_len(pkt) - netif->size); #endif } first_ext = pkt; for (ipv6 = pkt; ipv6 != NULL; ipv6 = ipv6->next) { /* find IPv6 header if already marked */ if ((ipv6->type == GNRC_NETTYPE_IPV6) && (ipv6->size == sizeof(ipv6_hdr_t)) && (ipv6_hdr_is(ipv6->data))) { break; } first_ext = ipv6; } if (ipv6 == NULL) { if (!ipv6_hdr_is(pkt->data)) { DEBUG("ipv6: Received packet was not IPv6, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } #ifdef MODULE_GNRC_IPV6_WHITELIST if (!gnrc_ipv6_whitelisted(&((ipv6_hdr_t *)(pkt->data))->src)) { DEBUG("ipv6: Source address not whitelisted, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } #endif #ifdef MODULE_GNRC_IPV6_BLACKLIST if (gnrc_ipv6_blacklisted(&((ipv6_hdr_t *)(pkt->data))->src)) { DEBUG("ipv6: Source address blacklisted, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } #endif /* seize ipv6 as a temporary variable */ ipv6 = gnrc_pktbuf_start_write(pkt); if (ipv6 == NULL) { DEBUG("ipv6: unable to get write access to packet, drop it\n"); gnrc_pktbuf_release(pkt); return; } pkt = ipv6; /* reset pkt from temporary variable */ ipv6 = gnrc_pktbuf_mark(pkt, sizeof(ipv6_hdr_t), GNRC_NETTYPE_IPV6); first_ext = pkt; pkt->type = GNRC_NETTYPE_UNDEF; /* snip is no longer IPv6 */ if (ipv6 == NULL) { DEBUG("ipv6: error marking IPv6 header, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } } #ifdef MODULE_GNRC_IPV6_WHITELIST else if (!gnrc_ipv6_whitelisted(&((ipv6_hdr_t *)(ipv6->data))->src)) { /* if ipv6 header already marked*/ DEBUG("ipv6: Source address not whitelisted, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } #endif #ifdef MODULE_GNRC_IPV6_BLACKLIST else if (gnrc_ipv6_blacklisted(&((ipv6_hdr_t *)(ipv6->data))->src)) { /* if ipv6 header already marked*/ DEBUG("ipv6: Source address blacklisted, dropping packet\n"); gnrc_pktbuf_release(pkt); return; } #endif /* extract header */ hdr = (ipv6_hdr_t *)ipv6->data; /* if available, remove any padding that was added by lower layers * to fulfill their minimum size requirements (e.g. ethernet) */ if (byteorder_ntohs(hdr->len) < pkt->size) { gnrc_pktbuf_realloc_data(pkt, byteorder_ntohs(hdr->len)); } else if (byteorder_ntohs(hdr->len) > (gnrc_pkt_len_upto(pkt, GNRC_NETTYPE_IPV6) - sizeof(ipv6_hdr_t))) { DEBUG("ipv6: invalid payload length: %d, actual: %d, dropping packet\n", (int) byteorder_ntohs(hdr->len), (int) (gnrc_pkt_len_upto(pkt, GNRC_NETTYPE_IPV6) - sizeof(ipv6_hdr_t))); gnrc_pktbuf_release(pkt); return; } DEBUG("ipv6: Received (src = %s, ", ipv6_addr_to_str(addr_str, &(hdr->src), sizeof(addr_str))); DEBUG("dst = %s, next header = %u, length = %" PRIu16 ")\n", ipv6_addr_to_str(addr_str, &(hdr->dst), sizeof(addr_str)), hdr->nh, byteorder_ntohs(hdr->len)); if (_pkt_not_for_me(&iface, hdr)) { /* if packet is not for me */ DEBUG("ipv6: packet destination not this host\n"); #ifdef MODULE_GNRC_IPV6_ROUTER /* only routers redirect */ /* redirect to next hop */ DEBUG("ipv6: decrement hop limit to %u\n", (uint8_t) (hdr->hl - 1)); /* RFC 4291, section 2.5.6 states: "Routers must not forward any * packets with Link-Local source or destination addresses to other * links." */ if ((ipv6_addr_is_link_local(&(hdr->src))) || (ipv6_addr_is_link_local(&(hdr->dst)))) { DEBUG("ipv6: do not forward packets with link-local source or" " destination address\n"); gnrc_pktbuf_release(pkt); return; } /* TODO: check if receiving interface is router */ else if (--(hdr->hl) > 0) { /* drop packets that *reach* Hop Limit 0 */ gnrc_pktsnip_t *reversed_pkt = NULL, *ptr = pkt; DEBUG("ipv6: forward packet to next hop\n"); /* pkt might not be writable yet, if header was given above */ ipv6 = gnrc_pktbuf_start_write(ipv6); if (ipv6 == NULL) { DEBUG("ipv6: unable to get write access to packet: dropping it\n"); gnrc_pktbuf_release(pkt); return; } /* remove L2 headers around IPV6 */ netif = gnrc_pktsnip_search_type(pkt, GNRC_NETTYPE_NETIF); if (netif != NULL) { gnrc_pktbuf_remove_snip(pkt, netif); } /* reverse packet snip list order */ while (ptr != NULL) { gnrc_pktsnip_t *next; ptr = gnrc_pktbuf_start_write(ptr); /* duplicate if not already done */ if (ptr == NULL) { DEBUG("ipv6: unable to get write access to packet: dropping it\n"); gnrc_pktbuf_release(reversed_pkt); gnrc_pktbuf_release(pkt); return; } next = ptr->next; ptr->next = reversed_pkt; reversed_pkt = ptr; ptr = next; } _send(reversed_pkt, false); return; } else { DEBUG("ipv6: hop limit reached 0: drop packet\n"); gnrc_pktbuf_release(pkt); return; } #else /* MODULE_GNRC_IPV6_ROUTER */ DEBUG("ipv6: dropping packet\n"); /* non rounting hosts just drop the packet */ gnrc_pktbuf_release(pkt); return; #endif /* MODULE_GNRC_IPV6_ROUTER */ } /* IPv6 internal demuxing (ICMPv6, Extension headers etc.) */ gnrc_ipv6_demux(iface, first_ext, pkt, hdr->nh); }