machine: make sure unpriviliged "machinectl status" can show the machine's OS version

[elogind.git] / src / libsystemd-network / dhcp-packet.c

diff --git a/src/libsystemd-network/dhcp-packet.c b/src/libsystemd-network/dhcp-packet.c
index d72d7a686de1a47a28f85685b5226c2bc7a45d7d..9f850fdebbf79835d9a5e751bfe3b8d4ceb6167f 100644 (file)
--- a/src/libsystemd-network/dhcp-packet.c
+++ b/src/libsystemd-network/dhcp-packet.c
@@ -38,8 +38,9 @@
 #define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
 
 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
-                      uint8_t type, uint8_t **opt, size_t *optlen) {
-        int err;
+                      uint8_t type, size_t optlen, size_t *optoffset) {
+        size_t offset = 0;
+        int r;
 
         assert(op == BOOTREQUEST || op == BOOTREPLY);
 
@@ -49,57 +50,42 @@ int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
         message->xid = htobe32(xid);
         message->magic = htobe32(DHCP_MAGIC_COOKIE);
 
-        *opt = (uint8_t *)(message + 1);
+        r = dhcp_option_append(message, optlen, &offset, 0,
+                               DHCP_OPTION_MESSAGE_TYPE, 1, &type);
+        if (r < 0)
+                return r;
 
-        err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1,
-                                 &type);
-        if (err < 0)
-                return err;
+        *optoffset = offset;
 
         return 0;
 }
 
-uint16_t dhcp_packet_checksum(void *buf, size_t len) {
-        uint64_t *buf_64 = buf;
-        uint64_t *end_64 = (uint64_t*)buf + (len / sizeof(uint64_t));
-        uint32_t *buf_32;
-        uint16_t *buf_16;
-        uint8_t *buf_8;
+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 ++;
         }
 
-        buf_32 = (uint32_t*)buf_64;
-
-        if (len & sizeof(uint32_t)) {
-                sum += *buf_32;
-                if (sum < *buf_32)
-                        sum++;
-
-                buf_32 ++;
-        }
-
-        buf_16 = (uint16_t*)buf_32;
-
-        if (len & sizeof(uint16_t)) {
-                sum += *buf_16;
-                if (sum < *buf_16)
-                        sum ++;
-
-                buf_16 ++;
-        }
+        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;
 
-        buf_8 = (uint8_t*)buf_16;
+                memcpy(&buf_tail, buf_64, len % sizeof(uint64_t));
 
-        if (len & sizeof(uint8_t)) {
-                sum += *buf_8;
-                if (sum < *buf_8)
+                sum += buf_tail;
+                if (sum < buf_tail)
+                        /* wrap around */
                         sum++;
         }
 
@@ -128,11 +114,11 @@ void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
         packet->udp.len = htobe16(len - DHCP_IP_SIZE);
 
         packet->ip.check = packet->udp.len;
-        packet->udp.check = dhcp_packet_checksum(&packet->ip.ttl, len - 8);
+        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(&packet->ip, DHCP_IP_SIZE);
+        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) {
@@ -192,7 +178,7 @@ int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
            if all the other checks have passed
          */
 
-        if (dhcp_packet_checksum(&packet->ip, hdrlen)) {
+        if (dhcp_packet_checksum((uint8_t*)&packet->ip, hdrlen)) {
                 log_debug("ignoring packet: invalid IP checksum");
                 return -EINVAL;
         }
@@ -201,7 +187,7 @@ int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) {
                 packet->ip.check = packet->udp.len;
                 packet->ip.ttl = 0;
 
-                if (dhcp_packet_checksum(&packet->ip.ttl,
+                if (dhcp_packet_checksum((uint8_t*)&packet->ip.ttl,
                                   be16toh(packet->udp.len) + 12)) {
                         log_debug("ignoring packet: invalid UDP checksum");
                         return -EINVAL;