/* -*- Mode: C; tab-width: 4 -*-
*
* Copyright (c) 2002-2004 Apple Computer, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if __APPLE__
// In Mac OS X 10.5 and later trying to use the daemon function gives a “‘daemon’ is deprecated”
// error, which prevents compilation because we build with "-Werror".
// Since this is supposed to be portable cross-platform code, we don't care that daemon is
// deprecated on Mac OS X 10.5, so we use this preprocessor trick to eliminate the error message.
#define daemon yes_we_know_that_daemon_is_deprecated_in_os_x_10_5_thankyou
#endif
#include <assert.h>
#include <stdio.h> // For printf()
#include <stdlib.h> // For exit() etc.
#include <string.h> // For strlen() etc.
#include <unistd.h> // For select()
#include <errno.h> // For errno, EINTR
#include <signal.h>
#include <fcntl.h>
#if __APPLE__
#undef daemon
extern int daemon(int, int);
#endif
#include "mDNSEmbeddedAPI.h" // Defines the interface to the client layer above
#include "mDNSPosix.h" // Defines the specific types needed to run mDNS on this platform
#include "mDNSUNP.h" // For daemon()
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark ***** Globals
#endif
static mDNS mDNSStorage; // mDNS core uses this to store its globals
static mDNS_PlatformSupport PlatformStorage; // Stores this platform's globals
mDNSexport const char ProgramName[] = "mDNSResponderPosix";
static const char *gProgramName = ProgramName;
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark ***** Signals
#endif
static volatile mDNSBool gReceivedSigUsr1;
static volatile mDNSBool gReceivedSigHup;
static volatile mDNSBool gStopNow;
// We support 4 signals.
//
// o SIGUSR1 toggles verbose mode on and off in debug builds
// o SIGHUP triggers the program to re-read its preferences.
// o SIGINT causes an orderly shutdown of the program.
// o SIGQUIT causes a somewhat orderly shutdown (direct but dangerous)
// o SIGKILL kills us dead (easy to implement :-)
//
// There are fatal race conditions in our signal handling, but there's not much
// we can do about them while remaining within the Posix space. Specifically,
// if a signal arrives after we test the globals its sets but before we call
// select, the signal will be dropped. The user will have to send the signal
// again. Unfortunately, Posix does not have a "sigselect" to atomically
// modify the signal mask and start a select.
static void HandleSigUsr1(int sigraised)
// If we get a SIGUSR1 we toggle the state of the
// verbose mode.
{
assert(sigraised == SIGUSR1);
gReceivedSigUsr1 = mDNStrue;
}
static void HandleSigHup(int sigraised)
// A handler for SIGHUP that causes us to break out of the
// main event loop when the user kill 1's us. This has the
// effect of triggered the main loop to deregister the
// current services and re-read the preferences.
{
assert(sigraised == SIGHUP);
gReceivedSigHup = mDNStrue;
}
static void HandleSigInt(int sigraised)
// A handler for SIGINT that causes us to break out of the
// main event loop when the user types ^C. This has the
// effect of quitting the program.
{
assert(sigraised == SIGINT);
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "\nSIGINT\n");
}
gStopNow = mDNStrue;
}
static void HandleSigQuit(int sigraised)
// If we get a SIGQUIT the user is desperate and we
// just call mDNS_Close directly. This is definitely
// not safe (because it could reenter mDNS), but
// we presume that the user has already tried the safe
// alternatives.
{
assert(sigraised == SIGQUIT);
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "\nSIGQUIT\n");
}
mDNS_Close(&mDNSStorage);
exit(0);
}
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark ***** Parameter Checking
#endif
static mDNSBool CheckThatRichTextNameIsUsable(const char *richTextName, mDNSBool printExplanation)
// Checks that richTextName is reasonable
// label and, if it isn't and printExplanation is true, prints
// an explanation of why not.
{
mDNSBool result = mDNStrue;
if (result && strlen(richTextName) > 63) {
if (printExplanation) {
fprintf(stderr,
"%s: Service name is too long (must be 63 characters or less)\n",
gProgramName);
}
result = mDNSfalse;
}
if (result && richTextName[0] == 0) {
if (printExplanation) {
fprintf(stderr, "%s: Service name can't be empty\n", gProgramName);
}
result = mDNSfalse;
}
return result;
}
static mDNSBool CheckThatServiceTypeIsUsable(const char *serviceType, mDNSBool printExplanation)
// Checks that serviceType is a reasonable service type
// label and, if it isn't and printExplanation is true, prints
// an explanation of why not.
{
mDNSBool result;
result = mDNStrue;
if (result && strlen(serviceType) > 63) {
if (printExplanation) {
fprintf(stderr,
"%s: Service type is too long (must be 63 characters or less)\n",
gProgramName);
}
result = mDNSfalse;
}
if (result && serviceType[0] == 0) {
if (printExplanation) {
fprintf(stderr,
"%s: Service type can't be empty\n",
gProgramName);
}
result = mDNSfalse;
}
return result;
}
static mDNSBool CheckThatPortNumberIsUsable(long portNumber, mDNSBool printExplanation)
// Checks that portNumber is a reasonable port number
// and, if it isn't and printExplanation is true, prints
// an explanation of why not.
{
mDNSBool result;
result = mDNStrue;
if (result && (portNumber <= 0 || portNumber > 65535)) {
if (printExplanation) {
fprintf(stderr,
"%s: Port number specified by -p must be in range 1..65535\n",
gProgramName);
}
result = mDNSfalse;
}
return result;
}
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark ***** Command Line Arguments
#endif
static const char kDefaultPIDFile[] = "/var/run/mDNSResponder.pid";
static const char kDefaultServiceType[] = "_afpovertcp._tcp.";
static const char kDefaultServiceDomain[] = "local.";
enum {
kDefaultPortNumber = 548
};
static void PrintUsage()
{
fprintf(stderr,
"Usage: %s [-v level ] [-r] [-n name] [-t type] [-d domain] [-p port] [-f file] [-b] [-P pidfile] [-x name=val ...]\n",
gProgramName);
fprintf(stderr, " -v verbose mode, level is a number from 0 to 2\n");
fprintf(stderr, " 0 = no debugging info (default)\n");
fprintf(stderr, " 1 = standard debugging info\n");
fprintf(stderr, " 2 = intense debugging info\n");
fprintf(stderr, " can be cycled kill -USR1\n");
fprintf(stderr, " -r also bind to port 53 (port 5353 is always bound)\n");
fprintf(stderr, " -n uses 'name' as the service name (required)\n");
fprintf(stderr, " -t uses 'type' as the service type (default is '%s')\n", kDefaultServiceType);
fprintf(stderr, " -d uses 'domain' as the service domain (default is '%s')\n", kDefaultServiceDomain);
fprintf(stderr, " -p uses 'port' as the port number (default is '%d')\n", kDefaultPortNumber);
fprintf(stderr, " -f reads a service list from 'file'\n");
fprintf(stderr, " -b forces daemon (background) mode\n");
fprintf(stderr, " -P uses 'pidfile' as the PID file\n");
fprintf(stderr, " (default is '%s')\n", kDefaultPIDFile);
fprintf(stderr, " only meaningful if -b also specified\n");
fprintf(stderr, " -x stores name=val in TXT record (default is empty).\n");
fprintf(stderr, " MUST be the last command-line argument;\n");
fprintf(stderr, " all subsequent arguments after -x are treated as name=val pairs.\n");
}
static mDNSBool gAvoidPort53 = mDNStrue;
static const char *gServiceName = "";
static const char *gServiceType = kDefaultServiceType;
static const char *gServiceDomain = kDefaultServiceDomain;
static mDNSu8 gServiceText[sizeof(RDataBody)];
static mDNSu16 gServiceTextLen = 0;
static int gPortNumber = kDefaultPortNumber;
static const char *gServiceFile = "";
static mDNSBool gDaemon = mDNSfalse;
static const char *gPIDFile = kDefaultPIDFile;
static void ParseArguments(int argc, char **argv)
// Parses our command line arguments into the global variables
// listed above.
{
int ch;
// Set gProgramName to the last path component of argv[0]
gProgramName = strrchr(argv[0], '/');
if (gProgramName == NULL) {
gProgramName = argv[0];
} else {
gProgramName += 1;
}
// Parse command line options using getopt.
do {
ch = getopt(argc, argv, "v:rn:t:d:p:f:dP:bx");
if (ch != -1) {
switch (ch) {
case 'v':
gMDNSPlatformPosixVerboseLevel = atoi(optarg);
if (gMDNSPlatformPosixVerboseLevel < 0 || gMDNSPlatformPosixVerboseLevel > 2) {
fprintf(stderr,
"%s: Verbose mode must be in the range 0..2\n",
gProgramName);
exit(1);
}
break;
case 'r':
gAvoidPort53 = mDNSfalse;
break;
case 'n':
gServiceName = optarg;
if ( !CheckThatRichTextNameIsUsable(gServiceName, mDNStrue) ) {
exit(1);
}
break;
case 't':
gServiceType = optarg;
if ( !CheckThatServiceTypeIsUsable(gServiceType, mDNStrue) ) {
exit(1);
}
break;
case 'd':
gServiceDomain = optarg;
break;
case 'p':
gPortNumber = atol(optarg);
if ( !CheckThatPortNumberIsUsable(gPortNumber, mDNStrue) ) {
exit(1);
}
break;
case 'f':
gServiceFile = optarg;
break;
case 'b':
gDaemon = mDNStrue;
break;
case 'P':
gPIDFile = optarg;
break;
case 'x':
while (optind < argc)
{
gServiceText[gServiceTextLen] = strlen(argv[optind]);
mDNSPlatformMemCopy(gServiceText+gServiceTextLen+1, argv[optind], gServiceText[gServiceTextLen]);
gServiceTextLen += 1 + gServiceText[gServiceTextLen];
optind++;
}
ch = -1;
break;
case '?':
default:
PrintUsage();
exit(1);
break;
}
}
} while (ch != -1);
// Check for any left over command line arguments.
if (optind != argc) {
PrintUsage();
fprintf(stderr, "%s: Unexpected argument '%s'\n", gProgramName, argv[optind]);
exit(1);
}
// Check for inconsistency between the arguments.
if ( (gServiceName[0] == 0) && (gServiceFile[0] == 0) ) {
PrintUsage();
fprintf(stderr, "%s: You must specify a service name to register (-n) or a service file (-f).\n", gProgramName);
exit(1);
}
}
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark ***** Registration
#endif
typedef struct PosixService PosixService;
struct PosixService {
ServiceRecordSet coreServ;
PosixService *next;
int serviceID;
};
static PosixService *gServiceList = NULL;
static void RegistrationCallback(mDNS *const m, ServiceRecordSet *const thisRegistration, mStatus status)
// mDNS core calls this routine to tell us about the status of
// our registration. The appropriate action to take depends
// entirely on the value of status.
{
switch (status) {
case mStatus_NoError:
debugf("Callback: %##s Name Registered", thisRegistration->RR_SRV.resrec.name->c);
// Do nothing; our name was successfully registered. We may
// get more call backs in the future.
break;
case mStatus_NameConflict:
debugf("Callback: %##s Name Conflict", thisRegistration->RR_SRV.resrec.name->c);
// In the event of a conflict, this sample RegistrationCallback
// just calls mDNS_RenameAndReregisterService to automatically
// pick a new unique name for the service. For a device such as a
// printer, this may be appropriate. For a device with a user
// interface, and a screen, and a keyboard, the appropriate response
// may be to prompt the user and ask them to choose a new name for
// the service.
//
// Also, what do we do if mDNS_RenameAndReregisterService returns an
// error. Right now I have no place to send that error to.
status = mDNS_RenameAndReregisterService(m, thisRegistration, mDNSNULL);
assert(status == mStatus_NoError);
break;
case mStatus_MemFree:
debugf("Callback: %##s Memory Free", thisRegistration->RR_SRV.resrec.name->c);
// When debugging is enabled, make sure that thisRegistration
// is not on our gServiceList.
#if !defined(NDEBUG)
{
PosixService *cursor;
cursor = gServiceList;
while (cursor != NULL) {
assert(&cursor->coreServ != thisRegistration);
cursor = cursor->next;
}
}
#endif
free(thisRegistration);
break;
default:
debugf("Callback: %##s Unknown Status %ld", thisRegistration->RR_SRV.resrec.name->c, status);
break;
}
}
static int gServiceID = 0;
static mStatus RegisterOneService(const char * richTextName,
const char * serviceType,
const char * serviceDomain,
const mDNSu8 text[],
mDNSu16 textLen,
long portNumber)
{
mStatus status;
PosixService * thisServ;
domainlabel name;
domainname type;
domainname domain;
status = mStatus_NoError;
thisServ = (PosixService *) malloc(sizeof(*thisServ));
if (thisServ == NULL) {
status = mStatus_NoMemoryErr;
}
if (status == mStatus_NoError) {
MakeDomainLabelFromLiteralString(&name, richTextName);
MakeDomainNameFromDNSNameString(&type, serviceType);
MakeDomainNameFromDNSNameString(&domain, serviceDomain);
status = mDNS_RegisterService(&mDNSStorage, &thisServ->coreServ,
&name, &type, &domain, // Name, type, domain
NULL, mDNSOpaque16fromIntVal(portNumber),
text, textLen, // TXT data, length
NULL, 0, // Subtypes
mDNSInterface_Any, // Interface ID
RegistrationCallback, thisServ, 0); // Callback, context, flags
}
if (status == mStatus_NoError) {
thisServ->serviceID = gServiceID;
gServiceID += 1;
thisServ->next = gServiceList;
gServiceList = thisServ;
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr,
"%s: Registered service %d, name \"%s\", type \"%s\", domain \"%s\", port %ld\n",
gProgramName,
thisServ->serviceID,
richTextName,
serviceType,
serviceDomain,
portNumber);
}
} else {
if (thisServ != NULL) {
free(thisServ);
}
}
return status;
}
static mDNSBool ReadALine(char *buf, size_t bufSize, FILE *fp, mDNSBool skipBlankLines)
{
size_t len;
mDNSBool readNextLine;
do {
readNextLine = mDNSfalse;
if (fgets(buf, bufSize, fp) == NULL)
return mDNSfalse; // encountered EOF or an error condition
// These first characters indicate a blank line.
if (buf[0] == ' ' || buf[0] == '\t' || buf[0] == '\r' || buf[0] == '\n') {
if (!skipBlankLines)
return mDNSfalse;
readNextLine = mDNStrue;
}
// always skip comment lines
if (buf[0] == '#')
readNextLine = mDNStrue;
} while (readNextLine);
len = strlen( buf);
if ( buf[len - 1] == '\r' || buf[len - 1] == '\n')
buf[len - 1] = '\0';
return mDNStrue;
}
static mStatus RegisterServicesInFile(const char *filePath)
{
mStatus status = mStatus_NoError;
FILE * fp = fopen(filePath, "r");
int rv;
if (fp == NULL) {
return mStatus_UnknownErr;
}
if (gMDNSPlatformPosixVerboseLevel > 1)
fprintf(stderr, "Parsing %s for services\n", filePath);
do {
char nameBuf[256];
char * name = nameBuf;
char type[256];
const char *dom = kDefaultServiceDomain;
char rawText[1024];
mDNSu8 text[sizeof(RDataBody)];
unsigned int textLen = 0;
char port[256];
char *p;
// Read the service name, type, port, and optional text record fields.
// Skip blank lines while looking for the next service name.
if (!ReadALine(name, sizeof(nameBuf), fp, mDNStrue))
break;
// Special case that allows service name to begin with a '#'
// character by escaping it with a '\' to distiguish it from
// a comment line. Remove the leading '\' here before
// registering the service.
if (name[0] == '\\' && name[1] == '#')
name++;
if (gMDNSPlatformPosixVerboseLevel > 1)
fprintf(stderr, "Service name: \"%s\"\n", name);
// Don't skip blank lines in calls to ReadAline() after finding the
// service name since the next blank line indicates the end
// of this service record.
if (!ReadALine(type, sizeof(type), fp, mDNSfalse))
break;
// see if a domain name is specified
p = type;
while (*p && *p != ' ' && *p != '\t') p++;
if (*p) {
*p = 0; // NULL terminate the <type>.<protocol> string
// skip any leading whitespace before domain name
p++;
while (*p && (*p == ' ' || *p == '\t')) p++;
if (*p)
dom = p;
}
if (gMDNSPlatformPosixVerboseLevel > 1) {
fprintf(stderr, "Service type: \"%s\"\n", type);
fprintf(stderr, "Service domain: \"%s\"\n", dom);
}
if (!ReadALine(port, sizeof(port), fp, mDNSfalse))
break;
if (gMDNSPlatformPosixVerboseLevel > 1)
fprintf(stderr, "Service port: %s\n", port);
if ( !CheckThatRichTextNameIsUsable(name, mDNStrue)
|| !CheckThatServiceTypeIsUsable(type, mDNStrue)
|| !CheckThatPortNumberIsUsable(atol(port), mDNStrue))
break;
// read the TXT record fields
while (1) {
int len;
if (!ReadALine(rawText, sizeof(rawText), fp, mDNSfalse)) break;
if (gMDNSPlatformPosixVerboseLevel > 1)
fprintf(stderr, "Text string: \"%s\"\n", rawText);
len = strlen(rawText);
if (len <= 255)
{
unsigned int newlen = textLen + 1 + len;
if (len == 0 || newlen >= sizeof(text)) break;
text[textLen] = len;
mDNSPlatformMemCopy(text + textLen + 1, rawText, len);
textLen = newlen;
}
else
fprintf(stderr, "%s: TXT attribute too long for name = %s, type = %s, port = %s\n",
gProgramName, name, type, port);
}
status = RegisterOneService(name, type, dom, text, textLen, atol(port));
if (status != mStatus_NoError) {
// print error, but try to read and register other services in the file
fprintf(stderr, "%s: Failed to register service, name \"%s\", type \"%s\", domain \"%s\", port %s\n",
gProgramName, name, type, dom, port);
}
} while (!feof(fp));
if (!feof(fp)) {
fprintf(stderr, "%s: Error reading service file %s\n", gProgramName, filePath);
status = mStatus_UnknownErr;
}
rv = fclose(fp);
assert(rv == 0);
return status;
}
static mStatus RegisterOurServices(void)
{
mStatus status;
status = mStatus_NoError;
if (gServiceName[0] != 0) {
status = RegisterOneService(gServiceName,
gServiceType,
gServiceDomain,
gServiceText, gServiceTextLen,
gPortNumber);
}
if (status == mStatus_NoError && gServiceFile[0] != 0) {
status = RegisterServicesInFile(gServiceFile);
}
return status;
}
static void DeregisterOurServices(void)
{
PosixService *thisServ;
int thisServID;
while (gServiceList != NULL) {
thisServ = gServiceList;
gServiceList = thisServ->next;
thisServID = thisServ->serviceID;
mDNS_DeregisterService(&mDNSStorage, &thisServ->coreServ);
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr,
"%s: Deregistered service %d\n",
gProgramName,
thisServ->serviceID);
}
}
}
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark **** Main
#endif
int main(int argc, char **argv)
{
mStatus status;
int result;
// Parse our command line arguments. This won't come back if there's an error.
ParseArguments(argc, argv);
// If we're told to run as a daemon, then do that straight away.
// Note that we don't treat the inability to create our PID
// file as an error. Also note that we assign getpid to a long
// because printf has no format specified for pid_t.
if (gDaemon) {
int result;
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "%s: Starting in daemon mode\n", gProgramName);
}
result = daemon(0,0);
if (result == 0) {
FILE *fp;
int junk;
fp = fopen(gPIDFile, "w");
if (fp != NULL) {
fprintf(fp, "%ld\n", (long) getpid());
junk = fclose(fp);
assert(junk == 0);
}
} else {
fprintf(stderr, "%s: Could not run as daemon - exiting\n", gProgramName);
exit(result);
}
} else {
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "%s: Starting in foreground mode, PID %ld\n", gProgramName, (long) getpid());
}
}
status = mDNS_Init(&mDNSStorage, &PlatformStorage,
mDNS_Init_NoCache, mDNS_Init_ZeroCacheSize,
mDNS_Init_AdvertiseLocalAddresses,
mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
if (status != mStatus_NoError) return(2);
status = RegisterOurServices();
if (status != mStatus_NoError) return(2);
signal(SIGHUP, HandleSigHup); // SIGHUP has to be sent by kill -HUP <pid>
signal(SIGINT, HandleSigInt); // SIGINT is what you get for a Ctrl-C
signal(SIGQUIT, HandleSigQuit); // SIGQUIT is what you get for a Ctrl-\ (indeed)
signal(SIGUSR1, HandleSigUsr1); // SIGUSR1 has to be sent by kill -USR1 <pid>
while (!gStopNow)
{
int nfds = 0;
fd_set readfds;
struct timeval timeout;
int result;
// 1. Set up the fd_set as usual here.
// This example client has no file descriptors of its own,
// but a real application would call FD_SET to add them to the set here
FD_ZERO(&readfds);
// 2. Set up the timeout.
// This example client has no other work it needs to be doing,
// so we set an effectively infinite timeout
timeout.tv_sec = FutureTime;
timeout.tv_usec = 0;
// 3. Give the mDNSPosix layer a chance to add its information to the fd_set and timeout
mDNSPosixGetFDSet(&mDNSStorage, &nfds, &readfds, &timeout);
// 4. Call select as normal
verbosedebugf("select(%d, %d.%06d)", nfds, timeout.tv_sec, timeout.tv_usec);
result = select(nfds, &readfds, NULL, NULL, &timeout);
if (result < 0)
{
verbosedebugf("select() returned %d errno %d", result, errno);
if (errno != EINTR) gStopNow = mDNStrue;
else
{
if (gReceivedSigUsr1)
{
gReceivedSigUsr1 = mDNSfalse;
gMDNSPlatformPosixVerboseLevel += 1;
if (gMDNSPlatformPosixVerboseLevel > 2)
gMDNSPlatformPosixVerboseLevel = 0;
if ( gMDNSPlatformPosixVerboseLevel > 0 )
fprintf(stderr, "\nVerbose level %d\n", gMDNSPlatformPosixVerboseLevel);
}
if (gReceivedSigHup)
{
if (gMDNSPlatformPosixVerboseLevel > 0)
fprintf(stderr, "\nSIGHUP\n");
gReceivedSigHup = mDNSfalse;
DeregisterOurServices();
status = mDNSPlatformPosixRefreshInterfaceList(&mDNSStorage);
if (status != mStatus_NoError) break;
status = RegisterOurServices();
if (status != mStatus_NoError) break;
}
}
}
else
{
// 5. Call mDNSPosixProcessFDSet to let the mDNSPosix layer do its work
mDNSPosixProcessFDSet(&mDNSStorage, &readfds);
// 6. This example client has no other work it needs to be doing,
// but a real client would do its work here
// ... (do work) ...
}
}
debugf("Exiting");
DeregisterOurServices();
mDNS_Close(&mDNSStorage);
if (status == mStatus_NoError) {
result = 0;
} else {
result = 2;
}
if ( (result != 0) || (gMDNSPlatformPosixVerboseLevel > 0) ) {
fprintf(stderr, "%s: Finished with status %d, result %d\n", gProgramName, (int)status, result);
}
return result;
}
