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MessageChannel.h
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MessageChannel.h
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/*
* Phusion Passenger - http://www.modrails.com/
* Copyright (c) 2010 Phusion
*
* "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef _PASSENGER_MESSAGE_CHANNEL_H_
#define _PASSENGER_MESSAGE_CHANNEL_H_
#include <oxt/system_calls.hpp>
#include <oxt/macros.hpp>
#include <algorithm>
#include <string>
#include <list>
#include <vector>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h>
#include <cstdarg>
#include <cmath>
#if !APR_HAVE_IOVEC
// We don't want apr_want.h to redefine 'struct iovec'.
// http://groups.google.com/group/phusion-passenger/browse_thread/thread/7e162f60df212e9c
#undef APR_HAVE_IOVEC
#define APR_HAVE_IOVEC 1
#endif
#include "StaticString.h"
#include "Exceptions.h"
#include "Utils/Timer.h"
#include "Utils/MemZeroGuard.h"
#include "Utils/IOUtils.h"
#include "Utils/MessageIO.h"
namespace Passenger {
using namespace std;
using namespace oxt;
/**
* Convenience class for I/O operations on file descriptors.
*
* This class provides convenience methods for:
* - sending and receiving raw data over a file descriptor.
* - sending and receiving messages over a file descriptor.
* - file descriptor passing over a Unix socket.
* - data size limit enforcement and time constraint enforcement.
* All of these methods use exceptions for error reporting.
*
* There are two kinds of messages:
* - Array messages. These are just a list of strings, and the message
* itself has a specific length. The contained strings may not
* contain NUL characters (<tt>'\\0'</tt>). Note that an array message
* must have at least one element.
* - Scalar messages. These are byte strings which may contain arbitrary
* binary data. Scalar messages also have a specific length.
* The protocol is designed to be low overhead, easy to implement and
* easy to parse.
*
* MessageChannel is to be wrapped around a file descriptor. For example:
* @code
* int p[2];
* pipe(p);
* MessageChannel channel1(p[0]);
* MessageChannel channel2(p[1]);
*
* // Send an array message.
* channel2.write("hello", "world !!", NULL);
* list<string> args;
* channel1.read(args); // args now contains { "hello", "world !!" }
*
* // Send a scalar message.
* channel2.writeScalar("some long string which can contain arbitrary binary data");
* string str;
* channel1.readScalar(str);
* @endcode
*
* The life time of a MessageChannel is independent from that of the
* wrapped file descriptor. If a MessageChannel object is destroyed,
* the file descriptor is not automatically closed. Call close()
* if you want to close the file descriptor.
*
* @note I/O operations are not buffered.
* @note Be careful with mixing the sending/receiving of array messages,
* scalar messages and file descriptors. If you send a collection of any
* of these in a specific order, then the receiving side must receive them
* in the exact some order. So suppose you first send a message, then a
* file descriptor, then a scalar, then the receiving side must first
* receive a message, then a file descriptor, then a scalar. If the
* receiving side does things in the wrong order then bad things will
* happen.
* @note MessageChannel is not thread-safe, but is reentrant.
* @note Some methods throw SecurityException and TimeoutException. When these
* exceptions are thrown, the channel will be left in an inconsistent state
* because only parts of the data have been read. You should close the channel
* after having caught these exceptions.
*
* @ingroup Support
*/
class MessageChannel {
private:
const static char DELIMITER = '\0';
int fd;
#ifdef __OpenBSD__
typedef u_int32_t uint32_t;
typedef u_int16_t uint16_t;
#endif
public:
/**
* Construct a new MessageChannel with no underlying file descriptor.
* Thus the resulting MessageChannel object will not be usable.
* This constructor exists to allow one to declare an "empty"
* MessageChannel variable which is to be initialized later.
*/
MessageChannel() {
this->fd = -1;
}
/**
* Construct a new MessageChannel with the given file descriptor.
*/
MessageChannel(int fd) {
this->fd = fd;
}
/**
* Returns the underlying file descriptor. -1 if it has already been closed.
*/
int filenum() const {
return fd;
}
/**
* Returns whether close() has been called.
*/
bool connected() const {
return fd != -1;
}
/**
* Close the underlying file descriptor. If this method is called multiple
* times, the file descriptor will only be closed the first time.
*
* @throw SystemException
* @throw boost::thread_interrupted
* @post filenum() == -1
* @post !connected()
*/
void close() {
if (fd != -1) {
int ret = syscalls::close(fd);
fd = -1;
if (ret == -1) {
throw SystemException("Cannot close file descriptor", errno);
}
}
}
/**
* Send an array message, which consists of the given elements, over the underlying
* file descriptor.
*
* @param args An object which contains the message elements. This object must
* support STL-style iteration, and each iterator must have an
* std::string as value. Use the StringArrayType and
* StringArrayConstIteratorType template parameters to specify the exact type names.
* @throws SystemException An error occured while writing the data to the file descriptor.
* @throws boost::thread_interrupted
* @pre None of the message elements may contain a NUL character (<tt>'\\0'</tt>).
* @see read(), write(const char *, ...)
*/
template<typename StringArrayType>
void write(const StringArrayType &args) {
writeArrayMessage(fd, args);
}
/**
* Send an array message, which consists of the given strings, over the underlying
* file descriptor. Like <tt>write(const char *name, ...)</tt> but takes a va_list
* instead.
*
* @throws SystemException An error occured while writing the data to the file descriptor.
* @throws boost::thread_interrupted
* @pre None of the message elements may contain a NUL character (<tt>'\\0'</tt>).
*/
void write(const char *name, va_list &ap) {
writeArrayMessage(fd, name, ap);
}
/**
* Send an array message, which consists of the given strings, over the underlying
* file descriptor.
*
* @param name The first element of the message to send.
* @param ... Other elements of the message. These *must* be strings, i.e. of type char*.
* It is also required to terminate this list with a NULL.
* @throws SystemException An error occured while writing the data to the file descriptor.
* @throws boost::thread_interrupted
* @pre None of the message elements may contain a NUL character (<tt>'\\0'</tt>).
* @see read(), write(const list<string> &)
*/
void write(const char *name, ...) {
va_list ap;
va_start(ap, name);
try {
write(name, ap);
va_end(ap);
} catch (...) {
va_end(ap);
throw;
}
}
/**
* Write a 32-bit big-endian unsigned integer to the underlying file descriptor.
*
* @throws SystemException An error occurred while writing the data to the file descriptor.
* @throws boost::thread_interrupted
*/
void writeUint32(unsigned int value) {
Passenger::writeUint32(fd, value);
}
/**
* Write a scalar message to the underlying file descriptor.
*
* @note Security guarantee: this method will not copy the data in memory,
* so it's safe to use this method to write passwords to the underlying
* file descriptor.
*
* @param str The scalar message's content.
* @throws SystemException An error occured while writing the data to the file descriptor.
* @throws boost::thread_interrupted
* @see readScalar(), writeScalar(const char *, unsigned int)
*/
void writeScalar(const string &str) {
writeScalarMessage(fd, str);
}
/**
* Write a scalar message to the underlying file descriptor.
*
* @note Security guarantee: this method will not copy the data in memory,
* so it's safe to use this method to write passwords to the underlying
* file descriptor.
*
* @param data The scalar message's content.
* @param size The number of bytes in <tt>data</tt>.
* @pre <tt>data != NULL</tt>
* @throws SystemException An error occured while writing the data to the file descriptor.
* @throws boost::thread_interrupted
* @see readScalar(), writeScalar(const string &)
*/
void writeScalar(const char *data, unsigned int size) {
writeScalarMessage(fd, data, size);
}
/**
* Pass a file descriptor. This only works if the underlying file
* descriptor is a Unix socket.
*
* @param fileDescriptor The file descriptor to pass.
* @param negotiate See Ruby's MessageChannel#send_io method's comments.
* @throws SystemException Something went wrong during file descriptor passing.
* @throws boost::thread_interrupted
* @pre <tt>fileDescriptor >= 0</tt>
* @see readFileDescriptor()
*/
void writeFileDescriptor(int fileDescriptor, bool negotiate = true) {
if (negotiate) {
Passenger::writeFileDescriptorWithNegotiation(fd, fileDescriptor);
} else {
Passenger::writeFileDescriptor(fd, fileDescriptor);
}
}
/**
* Read an array message from the underlying file descriptor.
*
* @param args The message will be put in this variable.
* @return Whether end-of-file has been reached. If so, then the contents
* of <tt>args</tt> will be undefined.
* @throws SystemException If an error occured while receiving the message.
* @throws boost::thread_interrupted
* @see write()
*/
bool read(vector<string> &args) {
try {
args = readArrayMessage(fd);
return true;
} catch (const EOFException &) {
return false;
}
}
/**
* Read a 32-bit big-endian unsigned integer from the underlying file descriptor.
*
* @param value Upon success, the read value will be stored in here.
* @param timeout A pointer to an integer, representing the maximum number of
* milliseconds to spend on reading the entire integer.
* A TimeoutException will be thrown if the timeout expires.
* If no exception is thrown, the the amount of time spent on waiting
* will be deducted from <tt>*timeout</tt>.
* Pass NULL if you do not want to enforce any time limits.
* @return True if a value was read, false if EOF was reached before all data can be
* read.
* @throws SystemException An error occurred while reading data from the file descriptor.
* @throws boost::thread_interrupted
*/
bool readUint32(unsigned int &value, unsigned long long *timeout = NULL) {
uint32_t temp;
if (!readRaw(&temp, sizeof(uint32_t), timeout)) {
return false;
} else {
value = ntohl(temp);
return true;
}
}
/**
* Read a scalar message from the underlying file descriptor.
*
* @param output The message will be put in here.
* @param maxSize The maximum number of bytes that may be read. If the
* scalar to read is larger than this, then a SecurityException
* will be thrown. Set to 0 for no size limit.
* @param timeout A pointer to an integer, representing the maximum number of
* milliseconds to spend on reading the entire scalar.
* A TimeoutException will be thrown if unable to read the entire
* scalar within this time period.
* If no exception is thrown, the the amount of time spent on waiting
* will be deducted from <tt>*timeout</tt>.
* Pass NULL if you do not want to enforce any time limits.
* @returns Whether end-of-file was reached during reading.
* @throws SystemException An error occured while reading data from the file descriptor.
* @throws SecurityException There is more data to read than allowed by maxSize.
* @throws TimeoutException Unable to read the entire scalar within <tt>timeout</tt>
* milliseconds.
* @throws boost::thread_interrupted
* @see writeScalar()
*/
bool readScalar(string &output, unsigned int maxSize = 0, unsigned long long *timeout = NULL) {
unsigned int size;
unsigned int remaining;
if (!readUint32(size, timeout)) {
return false;
}
if (maxSize != 0 && size > maxSize) {
throw SecurityException("There is more data available than is allowed by the size limit.");
}
output.clear();
output.reserve(size);
remaining = size;
if (OXT_LIKELY(remaining > 0)) {
char buf[1024 * 32];
// Wipe the buffer when we're done; it might contain sensitive data.
MemZeroGuard g(buf, sizeof(buf));
while (remaining > 0) {
unsigned int blockSize = min((unsigned int) sizeof(buf), remaining);
if (!readRaw(buf, blockSize, timeout)) {
return false;
}
output.append(buf, blockSize);
remaining -= blockSize;
}
}
return true;
}
/**
* Read exactly <tt>size</tt> bytes of data from the underlying file descriptor,
* and put the result in <tt>buf</tt>. If end-of-file has been reached, or if
* end-of-file was encountered before <tt>size</tt> bytes have been read, then
* <tt>false</tt> will be returned. Otherwise (i.e. if the read was successful),
* <tt>true</tt> will be returned.
*
* @param buf The buffer to place the read data in. This buffer must be at least
* <tt>size</tt> bytes long.
* @param size The number of bytes to read.
* @param timeout A pointer to an integer, which specifies the maximum number of
* milliseconds that may be spent on reading the <tt>size</tt> bytes
* of data. If the timeout expired then TimeoutException will be
* thrown.
* If this function returns without throwing an exception, then the
* total number of milliseconds spent on reading will be deducted
* from <tt>timeout</tt>.
* Pass NULL if you do not want to enforce a timeout.
* @return Whether reading was successful or whether EOF was reached.
* @pre buf != NULL
* @throws SystemException Something went wrong during reading.
* @throws TimeoutException Unable to read <tt>size</tt> bytes of data within
* <tt>timeout</tt> milliseconds.
* @throws boost::thread_interrupted
*/
bool readRaw(void *buf, unsigned int size, unsigned long long *timeout = NULL) {
if (timeout != NULL) {
unsigned long long t = *timeout * 1000;
unsigned int ret;
try {
ret = Passenger::readExact(fd, buf, size, &t);
#if defined(__NetBSD__) || defined(__OpenBSD__)
*timeout = llround((double) t / 1000);
#else
*timeout = llroundl((long double) t / 1000);
#endif
return ret == size;
} catch (...) {
#if defined(__NetBSD__) || defined(__OpenBSD__)
*timeout = llround((double) t / 1000);
#else
*timeout = llroundl((long double) t / 1000);
#endif
throw;
}
} else {
return Passenger::readExact(fd, buf, size) == size;
}
}
/**
* Receive a file descriptor, which had been passed over the underlying
* file descriptor.
*
* @param negotiate See Ruby's MessageChannel#send_io method's comments.
* @return The passed file descriptor.
* @throws SystemException If something went wrong during the
* receiving of a file descriptor. Perhaps the underlying
* file descriptor isn't a Unix socket.
* @throws IOException Whatever was received doesn't seem to be a
* file descriptor.
* @throws boost::thread_interrupted
*/
int readFileDescriptor(bool negotiate = true) {
if (negotiate) {
Passenger::readFileDescriptorWithNegotiation(fd);
} else {
Passenger::readFileDescriptor(fd);
}
}
/**
* Set the timeout value for reading data from this channel.
* If no data can be read within the timeout period, then a
* SystemException will be thrown by one of the read methods,
* with error code EAGAIN or EWOULDBLOCK.
*
* @param msec The timeout, in milliseconds. If 0 is given,
* there will be no timeout.
* @throws SystemException Cannot set the timeout.
*/
void setReadTimeout(unsigned int msec) {
// See the comment for setWriteTimeout().
struct timeval tv;
int ret;
tv.tv_sec = msec / 1000;
tv.tv_usec = msec % 1000 * 1000;
ret = syscalls::setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO,
&tv, sizeof(tv));
#ifndef __SOLARIS__
// SO_RCVTIMEO is unimplemented and returns an error on Solaris
// 9 and 10 SPARC. Seems to work okay without it.
if (ret == -1) {
throw SystemException("Cannot set read timeout for socket", errno);
}
#endif
}
/**
* Set the timeout value for writing data to this channel.
* If no data can be written within the timeout period, then a
* SystemException will be thrown, with error code EAGAIN or
* EWOULDBLOCK.
*
* @param msec The timeout, in milliseconds. If 0 is given,
* there will be no timeout.
* @throws SystemException Cannot set the timeout.
*/
void setWriteTimeout(unsigned int msec) {
// People say that SO_RCVTIMEO/SO_SNDTIMEO are unreliable and
// not well-implemented on all platforms.
// http://www.developerweb.net/forum/archive/index.php/t-3439.html
// That's why we use APR's timeout facilities as well (see Hooks.cpp).
struct timeval tv;
int ret;
tv.tv_sec = msec / 1000;
tv.tv_usec = msec % 1000 * 1000;
ret = syscalls::setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO,
&tv, sizeof(tv));
#ifndef __SOLARIS__
// SO_SNDTIMEO is unimplemented and returns an error on Solaris
// 9 and 10 SPARC. Seems to work okay without it.
if (ret == -1) {
throw SystemException("Cannot set read timeout for socket", errno);
}
#endif
}
};
} // namespace Passenger
#endif /* _PASSENGER_MESSAGE_CHANNEL_H_ */