Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 168 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp-packet.c b/src/libsystemd-network/dhcp-packet.c
new file mode 100644
index 0000000..ad5f8e2
--- /dev/null
+++ b/src/libsystemd-network/dhcp-packet.c
@@ -0,0 +1,168 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+/***
+  Copyright © 2013 Intel Corporation. All rights reserved.
+***/
+
+#include <errno.h>
+#include <net/ethernet.h>
+#include <net/if_arp.h>
+#include <string.h>
+
+#include "dhcp-internal.h"
+#include "dhcp-protocol.h"
+
+#define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
+
+int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
+                      uint8_t type, uint16_t arp_type, size_t optlen,
+                      size_t *optoffset) {
+        size_t offset = 0;
+        int r;
+
+        assert(IN_SET(op, BOOTREQUEST, BOOTREPLY));
+        assert(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND));
+
+        message->op = op;
+        message->htype = arp_type;
+        message->hlen = (arp_type == ARPHRD_ETHER) ? ETHER_ADDR_LEN : 0;
+        message->xid = htobe32(xid);
+        message->magic = htobe32(DHCP_MAGIC_COOKIE);
+
+        r = dhcp_option_append(message, optlen, &offset, 0,
+                               SD_DHCP_OPTION_MESSAGE_TYPE, 1, &type);
+        if (r < 0)
+                return r;
+
+        *optoffset = offset;
+
+        return 0;
+}
+
+uint16_t dhcp_packet_checksum(uint8_t *buf, size_t len) {
+        uint64_t *buf_64 = (uint64_t*)buf;
+        uint64_t *end_64 = buf_64 + (len / sizeof(uint64_t));
+        uint64_t sum = 0;
+
+        /* See RFC1071 */
+
+        while (buf_64 < end_64) {
+                sum += *buf_64;
+                if (sum < *buf_64)
+                        /* wrap around in one's complement */
+                        sum++;
+
+                buf_64++;
+        }
+
+        if (len % sizeof(uint64_t)) {
+                /* If the buffer is not aligned to 64-bit, we need
+                   to zero-pad the last few bytes and add them in */
+                uint64_t buf_tail = 0;
+
+                memcpy(&buf_tail, buf_64, len % sizeof(uint64_t));
+
+                sum += buf_tail;
+                if (sum < buf_tail)
+                        /* wrap around */
+                        sum++;
+        }
+
+        while (sum >> 16)
+                sum = (sum & 0xffff) + (sum >> 16);
+
+        return ~sum;
+}
+
+void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
+                                   uint16_t source_port, be32_t destination_addr,
+                                   uint16_t destination_port, uint16_t len) {
+        packet->ip.version = IPVERSION;
+        packet->ip.ihl = DHCP_IP_SIZE / 4;
+        packet->ip.tot_len = htobe16(len);
+
+        packet->ip.tos = IPTOS_CLASS_CS6;
+
+        packet->ip.protocol = IPPROTO_UDP;
+        packet->ip.saddr = source_addr;
+        packet->ip.daddr = destination_addr;
+
+        packet->udp.source = htobe16(source_port);
+        packet->udp.dest = htobe16(destination_port);
+
+        packet->udp.len = htobe16(len - DHCP_IP_SIZE);
+
+        packet->ip.check = packet->udp.len;
+        packet->udp.check = dhcp_packet_checksum((uint8_t*)&packet->ip.ttl, len - 8);
+
+        packet->ip.ttl = IPDEFTTL;
+        packet->ip.check = 0;
+        packet->ip.check = dhcp_packet_checksum((uint8_t*)&packet->ip, DHCP_IP_SIZE);
+}
+
+int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum, uint16_t port) {
+        size_t hdrlen;
+
+        assert(packet);
+
+        /* IP */
+
+        if (packet->ip.version != IPVERSION)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: not IPv4");
+
+        if (packet->ip.ihl < 5)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: IPv4 IHL (%u words) invalid",
+                                       packet->ip.ihl);
+
+        hdrlen = packet->ip.ihl * 4;
+        if (hdrlen < 20)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: IPv4 IHL (%zu bytes) "
+                                       "smaller than minimum (20 bytes)",
+                                       hdrlen);
+
+        if (len < hdrlen)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: packet (%zu bytes) "
+                                       "smaller than expected (%zu) by IP header",
+                                       len, hdrlen);
+
+        /* UDP */
+
+        if (packet->ip.protocol != IPPROTO_UDP)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: not UDP");
+
+        if (len < hdrlen + be16toh(packet->udp.len))
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: packet (%zu bytes) "
+                                       "smaller than expected (%zu) by UDP header",
+                                       len, hdrlen + be16toh(packet->udp.len));
+
+        if (be16toh(packet->udp.dest) != port)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: to port %u, which "
+                                       "is not the DHCP client port (%u)",
+                                       be16toh(packet->udp.dest), port);
+
+        /* checksums - computing these is relatively expensive, so only do it
+           if all the other checks have passed
+         */
+
+        if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen))
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ignoring packet: invalid IP checksum");
+
+        if (checksum && packet->udp.check) {
+                packet->ip.check = packet->udp.len;
+                packet->ip.ttl = 0;
+
+                if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl,
+                                  be16toh(packet->udp.len) + 12))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "ignoring packet: invalid UDP checksum");
+        }
+
+        return 0;
+}