Wiesner András
8676a392e5
- TCPWindow added - Checksum bug fixed (again) - CBD introduced - ConnBlock modified - PackSieve report funtionality modified to decrease memory consumption
117 lines
4.4 KiB
C
117 lines
4.4 KiB
C
//
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// Created by epagris on 2022.11.03..
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//
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#include <stdbool.h>
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#include "ethernet_frame.h"
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#include "ipv4_packet.h"
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#include "../../utils.h"
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#include "../../eth_interface.h"
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#define ETH_IP_HEADER_LENGTH (20)
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static bool check_ipv4_validity(const uint8_t *hdr, const IPv4Props *ipProps) {
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bool valid =
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(ipProps->Version == 4) &&
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(ipProps->IHL == (ETH_IP_HEADER_LENGTH / 4)) &&
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(chksum(hdr, ETH_IPv4_HEADER_SIZE, false) == 0) &&
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(ipProps->FragmentOffset == 0) && !(ipProps->Flags & 0x02 << 4); // TODO: discard if fragmented
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return valid;
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}
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int parse_ipv4(const uint8_t *hdr, uint32_t size, PcktHeaderElement *pcktHdrLe, struct EthInterface_ *intf) {
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const uint8_t *hdrBegin = hdr;
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IPv4Props *ipProps = HEADER_FETCH_PROPS(IPv4Props, pcktHdrLe);
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uint8_t version_length;
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FETCH_ADVANCE(&version_length, hdr, 1);
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ipProps->Version = (version_length) >> 4;
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ipProps->IHL = (version_length) & 0x0F;
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FETCH_ADVANCE(&ipProps->DSF, hdr, 1);
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FETCH_WORD_H2N_ADVANCE(&ipProps->TotalLength, hdr);
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FETCH_WORD_H2N_ADVANCE(&ipProps->Identification, hdr);
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uint16_t flags_fragOffset;
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FETCH_WORD_H2N_ADVANCE(&flags_fragOffset, hdr);
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ipProps->Flags = (flags_fragOffset >> 13) & 0x07;
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ipProps->FragmentOffset = (flags_fragOffset & ~(0x07 << 13));
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FETCH_ADVANCE(&ipProps->TTL, hdr, 1);
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FETCH_ADVANCE(&ipProps->Protocol, hdr, 1);
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FETCH_WORD_H2N_ADVANCE(&ipProps->HeaderChecksum, hdr);
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FETCH_ADVANCE(&ipProps->SourceIPAddr, hdr, 4); // NO network -> host byte order conversion!
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FETCH_ADVANCE(&ipProps->DestIPAddr, hdr, 4);
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// fill-in common packet header fields
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ipProps->validityOK = check_ipv4_validity(hdrBegin, ipProps);
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ipProps->containedPacketClass = ipProps->Protocol;
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ipProps->headerSize = ETH_IP_HEADER_LENGTH;
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// if packet is valid, learn MAC-IP mapping
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if (ipProps->validityOK) {
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EthernetProps *ethProps = HEADER_FETCH_PROPS(EthernetProps, pcktHdrLe->prev); // fetch Ethernet header
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ArpEntry entry; // fill entry
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memcpy(&entry.eth, ethProps->sourceAddr, ETH_HW_ADDR_LEN);
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entry.ip = ipProps->SourceIPAddr;
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arpc_learn(intf->arpc, &entry); // learn new assignment
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}
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return ipProps->validityOK ? ipProps->Protocol : -1;
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}
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static uint16_t nextIpIdentification = 0;
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void insert_ipv4_header(uint8_t *hdr, const PcktHeaderElement *headers) {
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uint8_t *hdrOrig = hdr;
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IPv4Props *ipProps = (IPv4Props *) &headers->props;
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ipProps->Identification = nextIpIdentification++; // auto-insert identification
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uint8_t version_length = (ipProps->Version << 4) | (ipProps->IHL & 0x0F);
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FILL_ADVANCE(hdr, &version_length, 1);
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FILL_ADVANCE(hdr, &ipProps->DSF, 1);
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FILL_WORD_H2N_ADVANCE(hdr, ipProps->TotalLength);
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FILL_WORD_H2N_ADVANCE(hdr, ipProps->Identification);
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uint16_t flags_fragOffset = ((ipProps->Flags & 0x07) << 13) | (ipProps->FragmentOffset & ~(0x07 << 13));
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FILL_WORD_H2N_ADVANCE(hdr, flags_fragOffset); // TODO...
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FILL_ADVANCE(hdr, &ipProps->TTL, 1);
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FILL_ADVANCE(hdr, &ipProps->Protocol, 1);
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uint8_t *ChkSumPtr = hdr;
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FILL_WORD_H2N_ADVANCE(hdr, 0x0000);
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FILL_ADVANCE(hdr, &ipProps->SourceIPAddr, 4);
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FILL_ADVANCE(hdr, &ipProps->DestIPAddr, 4);
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// calculate checksum after filling header
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ipProps->HeaderChecksum = chksum(hdrOrig, ETH_IPv4_HEADER_SIZE, false);
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memcpy(ChkSumPtr, &ipProps->HeaderChecksum, 2);
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}
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void ethmc_from_ipmc(uint8_t *hwa, ip4_addr ipa) {
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memcpy(hwa, ETH_ETHERNET_IPMC_HWADDR, ETH_HW_ADDR_LEN);
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const uint8_t *ipab = (const uint8_t *) &ipa;
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hwa[3] = (hwa[3] & 0x80) | (ipab[1] & 0x7F);
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hwa[4] = ipab[2];
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hwa[5] = ipab[3];
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}
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void ipv4_fill_props(IPv4Props *ipProps,
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uint32_t payloadSize,
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uint16_t protocol,
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ip4_addr srcIpA,
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ip4_addr dstIpA) {
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ipProps->IHL = ETH_IPv4_HEADER_SIZE / 4;
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ipProps->Version = 4;
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ipProps->DSF = 0x00;
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ipProps->TotalLength = ETH_IPv4_HEADER_SIZE + payloadSize;
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// Identification is filled on header insertion
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ipProps->Flags = 0x00;
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ipProps->FragmentOffset = 0x00;
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ipProps->TTL = 255;
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ipProps->Protocol = protocol;
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// HeaderChecksum is calculated on header insertion
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ipProps->SourceIPAddr = srcIpA;
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ipProps->DestIPAddr = dstIpA;
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// common fields for packet assembly
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ipProps->hdrInsFn = insert_ipv4_header;
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ipProps->headerSize = ETH_IPv4_HEADER_SIZE;
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}
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