#define IPV4_ERR_ADDR_INVALID -200001 #define IPV4_ERR_HOST_UNREACHABLE -200002 #define IPV4_TTL 64 //Look up IP Protocol Numbers online to see many more. #define IP_PROTOCOL_ICMP 0x01 #define IP_PROTOCOL_TCP 0x06 #define IP_PROTOCOL_UDP 0x11 class CIPV4Packet { CEthernetFrame *ethernet_frame; U32 source_ip_address; U32 destination_ip_address; U8 protocol; U8 padding[7]; U8 *data; I64 length; }; class CIPV4Header { // note: U4's in some U8s. U8 version_ihl; // Version for IPV4 is 4. IHL=Internet Header Length U8 dscp_ecn; // DSCP=Differentiated Services Code Point. ECN=Explicit Congestion Notification U16 total_length; // min 20B max 65535 U16 identification; U16 flags_fragment_offset; // flags first(?) 3 bits. fragment offset min 0 max 65528 // flag: bit 0: reserved must be 0. bit 1: don't fragment. bit 2: more fragments U8 time_to_live; // specified in seconds, wikipedia says nowadays serves as a hop count U8 protocol; U16 header_checksum; U32 source_ip_address; U32 destination_ip_address; }; class CIPV4Globals { // _be indicates Big Endian U32 local_ip; U32 local_ip_be; U32 ipv4_router_address; U32 ipv4_subnet_mask; } ipv4_globals; U0 IPV4GlobalsInit() { ipv4_globals.local_ip = 0; ipv4_globals.local_ip_be = 0; ipv4_globals.ipv4_router_address = 0; ipv4_globals.ipv4_subnet_mask = 0; }; // For now, trusting Shrine's implement // of checksum. Shrine links back to // http://stackoverflow.com/q/26774761/2524350 U16 IPV4Checksum(U8 *header, I64 length) { //todo. make names clearer, and better comments. I64 nleft = length; U16 *w = header; I64 sum = 0; while (nleft > 1) { sum += *w++; nleft -= 2; } // "mop up an odd byte, if necessary" if (nleft == 1) { sum += *w & 0x00FF; } // "add back carry outs from top 16 bits to low 16 bits" sum = sum >> 16 + sum & 0xFFFF; // "add hi 16 to low 16" sum += sum >> 16; // add carry return ~sum & 0xFFFF; } I64 IPV4AddressMACGet(U32 ip_address, U8 **mac_out) { CARPHash *entry; I64 retries; I64 attempt; if (ip_address == 0) { NetErr("GET MAC FOR IP: Failed. Address = 0"); return IPV4_ERR_ADDR_INVALID; } if (ip_address == 0xFFFFFFFF) { NetLog("GET MAC FOR IP: Returning ethernet broadcast"); *mac_out = ethernet_globals.ethernet_broadcast; return 0; } // "outside this subnet; needs routing" if (ip_address & ipv4_globals.ipv4_subnet_mask != ipv4_globals.local_ip & ipv4_globals.ipv4_subnet_mask) { NetWarn("GET MAC FOR IP: TODO: Doing IPV4AddressMACGet recursion, could infinite loop and overflow stack."); return IPV4AddressMACGet(ipv4_globals.ipv4_router_address, mac_out); } else // "local network" { NetLog("GET MAC FOR IP: Attempting ARP Find by IP for address: %0X.", ip_address); entry = ARPCacheFind(ip_address); if (entry) { *mac_out = entry->mac_address; return 0; } //else, not in cache, need to request it // "Up to 4 retries, 500 ms each" retries = 4; while (retries) { ARPSend(ARP_REQUEST, ethernet_globals.ethernet_broadcast, EthernetMACGet, ipv4_globals.local_ip_be, ethernet_globals.ethernet_null, EndianU32(ip_address)); attempt = 0; for (attempt = 0; attempt < 50; attempt++) { Sleep(10); entry = ARPCacheFind(ip_address); if (entry) break; } if (entry) { *mac_out = entry->mac_address; return 0; } retries--; } //Shrine does some in_addr mess to log error NetErr("GET MAC FOR IP: Failed to resolve address %d", ip_address); return IPV4_ERR_HOST_UNREACHABLE; } } I64 IPV4PacketAllocate(U8 **frame_out, U8 protocol, U32 source_ip_address, U32 destination_ip_address, I64 length) { U8 *ipv4_frame; U8 *destination_mac_address; I64 error; I64 de_index; I64 internet_header_length; CIPV4Header *header; error = IPV4AddressMACGet(destination_ip_address, &destination_mac_address); if (error < 0) { NetLog("IPV4 PACKET ALLOCATE: Failed to get MAC for destination."); return error; } de_index = EthernetFrameAllocate(&ipv4_frame, EthernetMACGet, destination_mac_address, ETHERTYPE_IPV4, sizeof(CIPV4Header) + length); if (de_index < 0) { NetLog("IPV4 PACKET ALLOCATE: Ethernet Frame Allocate failed."); return de_index; } internet_header_length = 5;// ... why. need a #define header = ipv4_frame; header->version_ihl = internet_header_length | 4 << 4;// ? TODO: needs #define header->dscp_ecn = 0; // a clear define of what this actually means would be good header->total_length = EndianU16(internet_header_length * 4 + length); //...why? header->identification = 0; // define would be clearer header->flags_fragment_offset = 0; // define would be clearer header->time_to_live = IPV4_TTL; header->protocol = protocol; header->header_checksum = 0; // why is 0 ok? header->source_ip_address = EndianU32(source_ip_address); header->destination_ip_address = EndianU32(destination_ip_address); header->header_checksum = IPV4Checksum(header, internet_header_length * 4);//why the 4's... *frame_out = ipv4_frame + sizeof(CIPV4Header); return de_index; } U0 IPV4PacketFinish(I64 de_index) //alias for EthernetFrameFinish { EthernetFrameFinish(de_index); } U32 IPV4AddressGet() { return ipv4_globals.local_ip; } U0 IPV4AddressSet(U32 ip_address) { ipv4_globals.local_ip = ip_address; ipv4_globals.local_ip_be = EndianU32(ip_address); ARPLocalIPV4Set(ip_address); } U0 IPV4SubnetSet(U32 router_address, U32 subnet_mask) { ipv4_globals.ipv4_router_address = router_address; ipv4_globals.ipv4_subnet_mask = subnet_mask; } //I64 U0 IPV4PacketParse(CIPV4Packet *packet_out, CEthernetFrame *ethernet_frame) { //...if ethertype not ipv4 error? // TODO: Check ethernet_frame length ! ... we need to know what's appropriate CIPV4Header *header = ethernet_frame->data; I64 header_length = (header->version_ihl & 0x0F) * 4;//this Has to go. at least abstract or something.. U16 total_length = EndianU16(header->total_length); packet_out->ethernet_frame = ethernet_frame; packet_out->source_ip_address = EndianU32(header->source_ip_address); packet_out->destination_ip_address = EndianU32(header->destination_ip_address); packet_out->protocol = header->protocol; packet_out->data = ethernet_frame->data + header_length; packet_out->length = total_length - header_length; // return 0; } U0 IPV4Rep() { "$LTBLUE$IPV4 Report:$FG$\n\n"; "Local IPV4: %d.%d.%d.%d\n", ipv4_globals.local_ip.u8[3], ipv4_globals.local_ip.u8[2], ipv4_globals.local_ip.u8[1], ipv4_globals.local_ip.u8[0]; "Router IPV4: %d.%d.%d.%d\n", ipv4_globals.ipv4_router_address.u8[3], ipv4_globals.ipv4_router_address.u8[2], ipv4_globals.ipv4_router_address.u8[1], ipv4_globals.ipv4_router_address.u8[0]; "Subnet IPV4: %d.%d.%d.%d\n", ipv4_globals.ipv4_subnet_mask.u8[3], ipv4_globals.ipv4_subnet_mask.u8[2], ipv4_globals.ipv4_subnet_mask.u8[1], ipv4_globals.ipv4_subnet_mask.u8[0]; "\n"; } // IPV4 handler moved to NetHandlerTask file. IPV4GlobalsInit;