servers/net: Make DHCP client more RFC 2131 compliant
* The client should enter state REBINDING only when RENEWING times out. * When in RENEWING or REBINDING state do not give up retrying unless the lease expires. * Fix bug sending 2^n DHCP requests at n-th lease renewal. * Use timeout values and renewal/rebinding times suggested by the RFC. * Use different XIDs in subsequent transactions.
This commit is contained in:
Pawel Dziepak
+189
-207
@@ -16,6 +16,7 @@
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#include <NetworkDevice.h>
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#include <NetworkInterface.h>
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#include <algorithm>
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#include <arpa/inet.h>
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#include <errno.h>
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#include <stdio.h>
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@@ -38,8 +39,10 @@
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#define DHCP_CLIENT_PORT 68
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#define DHCP_SERVER_PORT 67
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#define DEFAULT_TIMEOUT 2 // secs
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#define MAX_TIMEOUT 15 // secs
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#define DEFAULT_TIMEOUT 4 // secs
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#define MAX_TIMEOUT 64 // secs
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#define MAX_RETRIES 5
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enum message_opcode {
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BOOT_REQUEST = 1,
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@@ -427,10 +430,7 @@ DHCPClient::DHCPClient(BMessenger target, const char* device)
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fServer(AF_INET, NULL, DHCP_SERVER_PORT),
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fLeaseTime(0)
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{
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fStartTime = system_time();
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fTransactionID = (uint32)fStartTime;
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srand(fTransactionID);
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fTransactionID = (uint32)system_time() ^ rand();
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BNetworkAddress link;
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BNetworkInterface interface(device);
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@@ -498,13 +498,22 @@ DHCPClient::Initialize()
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status_t
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DHCPClient::_Negotiate(dhcp_state state)
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{
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if (state == BOUND)
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return B_OK;
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fStartTime = system_time();
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fTransactionID++;
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char hostName[MAXHOSTNAMELEN];
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if (gethostname(hostName, MAXHOSTNAMELEN) == 0)
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fHostName.SetTo(hostName, MAXHOSTNAMELEN);
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else
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fHostName.Truncate(0);
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int socket = ::socket(AF_INET, SOCK_DGRAM, 0);
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if (socket < 0)
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return errno;
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BNetworkAddress local;
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local.SetToWildcard(AF_INET, DHCP_CLIENT_PORT);
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// Enable reusing the port. This is needed in case there is more
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// than 1 interface that needs to be configured. Note that the only reason
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// this works is because there is code below to bind to a specific
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@@ -512,108 +521,69 @@ DHCPClient::_Negotiate(dhcp_state state)
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int option = 1;
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setsockopt(socket, SOL_SOCKET, SO_REUSEPORT, &option, sizeof(option));
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BNetworkAddress local;
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local.SetToWildcard(AF_INET, DHCP_CLIENT_PORT);
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option = 1;
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setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &option, sizeof(option));
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if (bind(socket, local, local.Length()) < 0) {
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close(socket);
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return errno;
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}
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BNetworkAddress broadcast;
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broadcast.SetToBroadcast(AF_INET, DHCP_SERVER_PORT);
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bigtime_t previousLeaseTime = fLeaseTime;
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option = 1;
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setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &option, sizeof(option));
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if (state == INIT) {
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// The local interface does not have an address yet, bind the socket
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// to the device directly.
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BNetworkDevice device(Device());
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int index = device.Index();
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setsockopt(socket, SOL_SOCKET, SO_BINDTODEVICE, &index, sizeof(int));
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status_t status = B_OK;
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while (state != BOUND) {
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status = _StateTransition(socket, state);
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if (status != B_OK && (state == SELECTING || state == REBOOTING))
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break;
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}
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bigtime_t previousLeaseTime = fLeaseTime;
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fLeaseTime = 0;
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fRenewalTime = 0;
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fRebindingTime = 0;
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close(socket);
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status_t status = B_ERROR;
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time_t timeout;
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uint32 tries;
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_ResetTimeout(socket, timeout, tries);
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if (fLeaseTime == 0)
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fLeaseTime = previousLeaseTime;
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if (fLeaseTime == 0)
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fLeaseTime = 60;
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char hostName[MAXHOSTNAMELEN];
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if (gethostname(hostName, MAXHOSTNAMELEN) == 0)
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fHostName.SetTo(hostName, MAXHOSTNAMELEN);
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else
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fHostName.Truncate(0);
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if (fRenewalTime == 0)
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fRenewalTime = fLeaseTime / 2;
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if (fRebindingTime == 0)
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fRebindingTime = fLeaseTime * 7 / 8;
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fLeaseTime += fRequestTime;
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fRenewalTime += fRequestTime;
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fRebindingTime += fRequestTime;
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_RestartLease(fRenewalTime);
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dhcp_message discover(DHCP_DISCOVER);
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_PrepareMessage(discover, state);
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fStatus = status;
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if (status)
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return status;
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dhcp_message request(DHCP_REQUEST);
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_PrepareMessage(request, state);
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// configure interface
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BMessage reply;
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status = Target().SendMessage(&fConfiguration, &reply);
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if (status == B_OK)
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status = reply.FindInt32("status", &fStatus);
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// send discover/request message
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_SendMessage(socket, state == INIT ? discover : request,
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state != RENEWING ? broadcast : fServer);
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// no need to check the status; in case of an error we'll just send
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// the message again
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// configure resolver
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reply.MakeEmpty();
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fResolverConfiguration.AddString("device", Device());
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status = Target().SendMessage(&fResolverConfiguration, &reply);
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if (status == B_OK)
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status = reply.FindInt32("status", &fStatus);
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return status;
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}
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// receive loop until we've got an offer and acknowledged it
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while (state != BOUND) {
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char buffer[2048];
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struct sockaddr_in from;
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socklen_t fromLength = sizeof(from);
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ssize_t bytesReceived = recvfrom(socket, buffer, sizeof(buffer),
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0, (struct sockaddr*)&from, &fromLength);
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if (bytesReceived < 0 && errno == B_TIMED_OUT) {
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// depending on the state, we'll just try again
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if (!_TimeoutShift(socket, timeout, tries)) {
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close(socket);
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return B_TIMED_OUT;
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}
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_SendMessage(socket, state == INIT ? discover : request,
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state != RENEWING ? broadcast : fServer);
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continue;
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} else if (bytesReceived < 0)
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break;
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dhcp_message* message = (dhcp_message*)buffer;
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if (message->transaction_id != htonl(fTransactionID)
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|| !message->HasOptions()
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|| memcmp(message->mac_address, discover.mac_address,
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discover.hardware_address_length)) {
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// this message is not for us
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continue;
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}
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// advance from startup state
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if (state == INIT)
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state = SELECTING;
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else if (state == INIT_REBOOT)
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state = REBOOTING;
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syslog(LOG_DEBUG, "%s: Received %s from %s\n",
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Device(), dhcp_message::TypeToString(message->Type()),
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_AddressToString(from.sin_addr.s_addr).String());
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switch (message->Type()) {
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case DHCP_NONE:
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default:
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// ignore this message
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break;
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case DHCP_OFFER:
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{
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// first offer wins
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if (state != SELECTING)
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break;
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// collect interface options
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status_t
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DHCPClient::_GotMessage(dhcp_state& state, dhcp_message* message)
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{
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switch (state) {
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case SELECTING:
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if (message->Type() == DHCP_OFFER) {
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state = REQUESTING;
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fAssignedAddress = message->your_address;
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syslog(LOG_INFO, " your_address: %s\n",
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@@ -630,27 +600,16 @@ DHCPClient::_Negotiate(dhcp_state state)
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_ParseOptions(*message, address, fResolverConfiguration);
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fConfiguration.AddMessage("address", &address);
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// request configuration from the server
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_ResetTimeout(socket, timeout, tries);
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state = REQUESTING;
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_PrepareMessage(request, state);
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status = _SendMessage(socket, request, broadcast);
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// we're sending a broadcast so that all potential offers
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// get an answer
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break;
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return B_OK;
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}
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case DHCP_ACK:
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{
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if (state != REQUESTING
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&& state != REBOOTING
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&& state != REBINDING
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&& state != RENEWING)
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continue;
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return B_BAD_VALUE;
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case REBOOTING:
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case REBINDING:
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case RENEWING:
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case REQUESTING:
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if (message->Type() == DHCP_ACK) {
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// TODO: we might want to configure the stuff, don't we?
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BMessage address;
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fResolverConfiguration.MakeEmpty();
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@@ -661,67 +620,96 @@ DHCPClient::_Negotiate(dhcp_state state)
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// our address request has been acknowledged
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state = BOUND;
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// configure interface
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BMessage reply;
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status = Target().SendMessage(&fConfiguration, &reply);
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if (status == B_OK)
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status = reply.FindInt32("status", &fStatus);
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// configure resolver
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reply.MakeEmpty();
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fResolverConfiguration.AddString("device", Device());
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status = Target().SendMessage(&fResolverConfiguration, &reply);
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if (status == B_OK)
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status = reply.FindInt32("status", &fStatus);
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break;
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return B_OK;
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}
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case DHCP_NACK:
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if (state != REQUESTING
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&& state != REBOOTING
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&& state != REBINDING
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&& state != RENEWING)
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continue;
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if (message->Type() == DHCP_NACK) {
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// server reject our request on previous assigned address
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// back to square one...
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fAssignedAddress = 0;
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state = INIT;
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return B_OK;
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}
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if (state == REBOOTING) {
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// server reject our request on previous assigned address
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// back to square one...
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fAssignedAddress = 0;
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}
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default:
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return B_BAD_VALUE;
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}
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}
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// try again (maybe we should prefer other servers if this
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// happens more than once)
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status = _SendMessage(socket, discover, broadcast);
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if (status == B_OK)
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state = INIT;
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break;
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status_t
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DHCPClient::_StateTransition(int socket, dhcp_state& state)
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{
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if (state == INIT) {
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// The local interface does not have an address yet, bind the socket
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// to the device directly.
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BNetworkDevice device(Device());
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int index = device.Index();
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setsockopt(socket, SOL_SOCKET, SO_BINDTODEVICE, &index, sizeof(int));
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}
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BNetworkAddress broadcast;
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broadcast.SetToBroadcast(AF_INET, DHCP_SERVER_PORT);
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time_t timeout;
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uint32 tries;
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_ResetTimeout(socket, state, timeout, tries);
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dhcp_message discover(DHCP_DISCOVER);
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_PrepareMessage(discover, state);
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dhcp_message request(DHCP_REQUEST);
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_PrepareMessage(request, state);
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bool skipRequest = false;
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dhcp_state originalState = state;
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fRequestTime = system_time();
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while (true) {
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if (!skipRequest) {
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_SendMessage(socket, originalState == INIT ? discover : request,
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originalState == RENEWING ? fServer : broadcast);
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if (originalState == INIT)
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state = SELECTING;
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else if (originalState == INIT_REBOOT)
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state = REBOOTING;
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}
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char buffer[2048];
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struct sockaddr_in from;
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socklen_t fromLength = sizeof(from);
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ssize_t bytesReceived = recvfrom(socket, buffer, sizeof(buffer),
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0, (struct sockaddr*)&from, &fromLength);
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if (bytesReceived < 0 && errno == B_TIMED_OUT) {
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// depending on the state, we'll just try again
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if (!_TimeoutShift(socket, state, timeout, tries))
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return B_TIMED_OUT;
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skipRequest = false;
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continue;
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} else if (bytesReceived < 0)
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return errno;
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skipRequest = true;
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dhcp_message* message = (dhcp_message*)buffer;
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if (message->transaction_id != htonl(fTransactionID)
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|| !message->HasOptions()
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|| memcmp(message->mac_address, discover.mac_address,
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discover.hardware_address_length)) {
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// this message is not for us
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continue;
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}
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syslog(LOG_DEBUG, "%s: Received %s from %s\n",
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Device(), dhcp_message::TypeToString(message->Type()),
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_AddressToString(from.sin_addr.s_addr).String());
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if (_GotMessage(state, message) == B_OK)
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break;
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}
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close(socket);
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if (status == B_OK && fLeaseTime > 0) {
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// notify early enough when the lease is
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if (fRenewalTime == 0)
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fRenewalTime = fLeaseTime * 2/3;
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if (fRebindingTime == 0)
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fRebindingTime = fLeaseTime * 5/6;
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bigtime_t now = system_time();
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_RestartLease(fRenewalTime);
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fLeaseTime += now;
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fRenewalTime += now;
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fRebindingTime += now;
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// make lease times absolute
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} else {
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fLeaseTime = previousLeaseTime;
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bigtime_t now = system_time();
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fRenewalTime = (fLeaseTime - now) * 2/3 + now;
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fRebindingTime = (fLeaseTime - now) * 5/6 + now;
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}
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return status;
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return B_OK;
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}
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@@ -732,7 +720,7 @@ DHCPClient::_RestartLease(bigtime_t leaseTime)
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return;
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BMessage lease(kMsgLeaseTime);
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fRunner = new BMessageRunner(this, &lease, leaseTime, 1);
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fRunner = new BMessageRunner(this, &lease, leaseTime - system_time(), 1);
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}
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@@ -899,7 +887,8 @@ DHCPClient::_PrepareMessage(dhcp_message& message, dhcp_state state)
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void
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DHCPClient::_ResetTimeout(int socket, time_t& timeout, uint32& tries)
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DHCPClient::_ResetTimeout(int socket, dhcp_state& state, time_t& timeout,
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uint32& tries)
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{
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timeout = DEFAULT_TIMEOUT;
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tries = 0;
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@@ -912,15 +901,36 @@ DHCPClient::_ResetTimeout(int socket, time_t& timeout, uint32& tries)
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bool
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DHCPClient::_TimeoutShift(int socket, time_t& timeout, uint32& tries)
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DHCPClient::_TimeoutShift(int socket, dhcp_state& state, time_t& timeout,
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uint32& tries)
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{
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timeout += timeout;
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if (timeout > MAX_TIMEOUT) {
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timeout = DEFAULT_TIMEOUT;
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if (++tries > 2)
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return false;
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if (state == RENEWING && system_time() > fRebindingTime) {
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state = REBINDING;
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return false;
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}
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if (state == REBINDING && system_time() > fLeaseTime) {
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state = INIT;
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return false;
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}
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tries++;
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timeout += timeout;
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if (timeout > MAX_TIMEOUT)
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timeout = MAX_TIMEOUT;
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if (tries > MAX_RETRIES) {
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bigtime_t remaining = 0;
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if (state == RENEWING)
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remaining = (fRebindingTime - system_time()) / 2 + 1;
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else if (state == REBINDING)
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remaining = (fLeaseTime - system_time()) / 2 + 1;
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else
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return false;
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timeout = std::max(remaining / 1000000, bigtime_t(60));
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}
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syslog(LOG_DEBUG, "%s: Timeout shift: %lu secs (try %lu)\n",
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Device(), timeout, tries);
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@@ -978,13 +988,12 @@ DHCPClient::_CurrentState() const
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{
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bigtime_t now = system_time();
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if (now > fLeaseTime || fStatus < B_OK)
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if (now > fLeaseTime || fStatus != B_OK)
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return INIT;
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if (now >= fRebindingTime)
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return REBINDING;
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if (now >= fRenewalTime)
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return RENEWING;
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return BOUND;
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}
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@@ -994,35 +1003,8 @@ DHCPClient::MessageReceived(BMessage* message)
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{
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switch (message->what) {
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case kMsgLeaseTime:
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{
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dhcp_state state = _CurrentState();
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||||
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bigtime_t next;
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if (_Negotiate(state) == B_OK) {
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switch (state) {
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case RENEWING:
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next = fRebindingTime;
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break;
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case REBINDING:
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default:
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next = fRenewalTime;
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break;
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}
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} else {
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switch (state) {
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case RENEWING:
|
||||
next = (fLeaseTime - fRebindingTime) / 4 + system_time();
|
||||
break;
|
||||
case REBINDING:
|
||||
default:
|
||||
next = (fLeaseTime - fRenewalTime) / 4 + system_time();
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
_RestartLease(next - system_time());
|
||||
_Negotiate(_CurrentState());
|
||||
break;
|
||||
}
|
||||
|
||||
default:
|
||||
BHandler::MessageReceived(message);
|
||||
|
||||
@@ -44,6 +44,9 @@ public:
|
||||
|
||||
private:
|
||||
status_t _Negotiate(dhcp_state state);
|
||||
status_t _GotMessage(dhcp_state& state,
|
||||
dhcp_message* message);
|
||||
status_t _StateTransition(int socket, dhcp_state& state);
|
||||
void _ParseOptions(dhcp_message& message,
|
||||
BMessage& address,
|
||||
BMessage& resolverConfiguration);
|
||||
@@ -52,10 +55,10 @@ private:
|
||||
status_t _SendMessage(int socket, dhcp_message& message,
|
||||
const BNetworkAddress& address) const;
|
||||
dhcp_state _CurrentState() const;
|
||||
void _ResetTimeout(int socket, time_t& timeout,
|
||||
uint32& tries);
|
||||
bool _TimeoutShift(int socket, time_t& timeout,
|
||||
uint32& tries);
|
||||
void _ResetTimeout(int socket, dhcp_state& state,
|
||||
time_t& timeout, uint32& tries);
|
||||
bool _TimeoutShift(int socket, dhcp_state& state,
|
||||
time_t& timeout, uint32& tries);
|
||||
void _RestartLease(bigtime_t lease);
|
||||
|
||||
static BString _AddressToString(const uint8* data);
|
||||
@@ -71,6 +74,7 @@ private:
|
||||
in_addr_t fAssignedAddress;
|
||||
BNetworkAddress fServer;
|
||||
bigtime_t fStartTime;
|
||||
bigtime_t fRequestTime;
|
||||
bigtime_t fRenewalTime;
|
||||
bigtime_t fRebindingTime;
|
||||
bigtime_t fLeaseTime;
|
||||
|
||||
@@ -1388,6 +1388,8 @@ NetServer::_ConvertNetworkFromSettings(BMessage& message)
|
||||
int
|
||||
main(int argc, char** argv)
|
||||
{
|
||||
srand(system_time());
|
||||
|
||||
status_t status;
|
||||
NetServer server(status);
|
||||
if (status != B_OK) {
|
||||
|
||||
Reference in New Issue
Block a user