tarsnap/lib/network/tsnetwork_buf.c

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <errno.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "tarsnap_opt.h"
#include "tsnetwork_internal.h"
#include "tvmath.h"
#include "warnp.h"

#include "tsnetwork.h"

#define RECV 0
#define SEND 1

/*
 * If MSG_NOSIGNAL isn't defined, define it to zero; and then fiddle with
 * the socket options when needed.
 */
#ifdef MSG_NOSIGNAL
#define HAVE_MSG_NOSIGNAL
#endif
#ifndef HAVE_MSG_NOSIGNAL
#define MSG_NOSIGNAL 0
#endif

struct network_buf_cookie {
	network_callback * callback;
	void * cookie;
	int fd;
	uint8_t * buf;
	size_t buflen;
	size_t bufpos;
	struct timeval timeout;
	struct timeval timeout_max;
	int sendrecv;
	int netop;
	int flags;
};

static int callback_buf(void * cookie, int status);
static int network_buf(int fd, uint8_t * buf, size_t buflen,
    struct timeval * to0, struct timeval * to1,
    network_callback * callback, void * cookie,
    int sendrecv, int netop, int flags);

/**
 * callback_buf(cookie, status):
 * Callback helper for tsnetwork_read and network_write.
 */
static int
callback_buf(void * cookie, int status)
{
	struct network_buf_cookie * C = cookie;
	struct timeval timeo;
	size_t bwlimit;
	size_t oplen;
	ssize_t len;
	int rc = -1;	/* If not callback or reset, we have an error. */
#ifndef HAVE_MSG_NOSIGNAL
	int saved_errno;
#ifdef SO_NOSIGPIPE
	int val;
#else
	void (* oldsig)(int);
#endif
#endif

	if (status != NETWORK_STATUS_OK) {
		/* If we have no data, mark a timeout as "no data" instead. */
		if ((C->bufpos != 0) && (status == NETWORK_STATUS_TIMEOUT))
			status = NETWORK_STATUS_NODATA;
		goto docallback;
	}

	/* Figure out how far we have bandwidth quota for. */
	if (network_bwlimit_get(C->netop, &bwlimit)) {
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}

	/* If we have no bandwidth, schedule another callback. */
	if (bwlimit == 0)
		goto tryagain;

	/* Try to read/write data to/from the buffer. */
#ifndef HAVE_MSG_NOSIGNAL
#ifdef SO_NOSIGPIPE
	val = 1;

	if (setsockopt(C->fd, SOL_SOCKET, SO_NOSIGPIPE, &val, sizeof(int))) {
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}
#else
	if ((oldsig = signal(SIGPIPE, SIG_IGN)) == SIG_ERR) {
		warnp("signal(SIGPIPE)");
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}
#endif
#endif

	oplen = C->buflen - C->bufpos;
	if (oplen > bwlimit)
		oplen = bwlimit;
	/* Send or recv. */
	if (C->sendrecv == SEND)
		len = send(C->fd, C->buf + C->bufpos, oplen, C->flags);
	else
		len = recv(C->fd, C->buf + C->bufpos, oplen, C->flags);
#ifndef HAVE_MSG_NOSIGNAL
	/* Save errno in case it gets clobbered by setsockopt() or signal(). */
	saved_errno = errno;
#ifdef SO_NOSIGPIPE
	val = 0;

	if (setsockopt(C->fd, SOL_SOCKET, SO_NOSIGPIPE, &val, sizeof(int))) {
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}
#else
	if (signal(SIGPIPE, oldsig) == SIG_ERR) {
		warnp("signal(SIGPIPE)");
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}
#endif
	/* Restore saved errno. */
	errno = saved_errno;
#endif

	/* Failure, closed, or success? */
	if (len == -1) {
		/* If no data is available, reset the callback. */
		if ((errno == EAGAIN) ||
#if EAGAIN != EWOULDBLOCK
		    (errno == EWOULDBLOCK) ||
#endif
		    (errno == EINTR))
			goto tryagain;

		/* An error occurred.  Let the callback handle it. */
		status = NETWORK_STATUS_ERR;
		goto docallback;
	} else if (len == 0) {
		/* Socket has been shut down by remote host. */
		/* This should occur only when receiving, not when sending. */
		status = NETWORK_STATUS_CLOSED;
		goto docallback;
	} else {
		/* Adjust bandwidth limit. */
		if (network_bwlimit_eat(C->netop, (size_t)len)) {
			status = NETWORK_STATUS_ERR;
			goto docallback;
		}

		/* Data has been read/written into/from buffer. */
		C->bufpos += (size_t)len;
		if (C->bufpos == C->buflen) {
			status = NETWORK_STATUS_OK;
			goto docallback;
		}

		/* Fall through to resetting the callback. */
	}

tryagain:
	/* We need more data.  Reset the callback. */
	memcpy(&timeo, &C->timeout, sizeof(struct timeval));
	if (tvmath_subctime(&timeo)) {
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}
	if (tv_lt(&C->timeout_max, &timeo))
		memcpy(&timeo, &C->timeout_max, sizeof(struct timeval));
	if (network_register(C->fd, C->netop, &timeo, callback_buf, C)) {
		status = NETWORK_STATUS_ERR;
		goto docallback;
	}

	/* Callback has been reset. */
	return (0);

docallback:
	/*
	 * If there was a network error and we're being verbose, print the
	 * error now in case errno gets mangled later.
	 */
	if ((tarsnap_opt_noisy_warnings) && (status == NETWORK_STATUS_ERR))
		warnp("Network error");

	/* Call the user callback. */
	rc = (C->callback)(C->cookie, status);

	/* Free the cookie. */
	free(C);

	/* Return error or value from user callback. */
	return (rc);
}

/**
 * network_buf(fd, buf, buflen, to0, to1, callback, cookie, sendrecv, netop,
 *     flags):
 * Asynchronously read/write the provided buffer from/to ${fd}, and call
 * callback(cookie, status) where status is a NETWORK_STATUS_* value.  Time
 * out if no data can be read/writ for a period of time to0, or if the
 * complete buffer has not been read/writ after time to1.
 */
static int
network_buf(int fd, uint8_t * buf, size_t buflen,
    struct timeval * to0, struct timeval * to1,
    network_callback * callback, void * cookie,
    int sendrecv, int netop, int flags)
{
	struct network_buf_cookie * C;
	struct timeval timeo;

	/* Create a cookie to be passed to callback_buf. */
	if ((C = malloc(sizeof(struct network_buf_cookie))) == NULL)
		goto err0;
	C->callback = callback;
	C->cookie = cookie;
	C->fd = fd;
	C->buf = buf;
	C->buflen = buflen;
	C->bufpos = 0;
	C->sendrecv = sendrecv;
	C->netop = netop;
	C->flags = flags;

	/* Figure out when we should give up waiting. */
	memcpy(&C->timeout, to1, sizeof(struct timeval));
	if (tvmath_addctime(&C->timeout))
		goto err1;

	/* Record the maximum time that any single send/recv will wait. */
	memcpy(&C->timeout_max, to0, sizeof(struct timeval));

	/* Set up the callback. */
	memcpy(&timeo, to1, sizeof(struct timeval));
	if (tv_lt(to0, &timeo))
		memcpy(&timeo, to0, sizeof(struct timeval));
	if (network_register(fd, netop, &timeo, callback_buf, C))
		goto err1;

	/* Success! */
	return (0);

err1:
	free(C);
err0:
	/* Failure! */
	return (-1);
}

/**
 * tsnetwork_read(fd, buf, buflen, to0, to1, callback, cookie):
 * Asynchronously fill the provided buffer with data from ${fd}, and call
 * callback(cookie, status) where status is a NETWORK_STATUS_* value.  Time
 * out if no data can be read for a period of time to0, or if the complete
 * buffer has not been read after time to1.  Note that ${buflen} must be
 * non-zero, since otherwise deadlock would result.
 */
int
tsnetwork_read(int fd, uint8_t * buf, size_t buflen,
    struct timeval * to0, struct timeval * to1,
    network_callback * callback, void * cookie)
{

	/* Make sure buflen is non-zero. */
	if (buflen == 0) {
		warn0("Cannot read zero-byte buffer");
		return (-1);
	}

	return (network_buf(fd, buf, buflen, to0, to1, callback, cookie,
	    RECV, NETWORK_OP_READ, 0));
}

/**
 * tsnetwork_write(fd, buf, buflen, to0, to1, callback, cookie):
 * Asynchronously write data from the provided buffer to ${fd}, and call
 * callback(cookie, status) where status is a NETWORK_STATUS_* value.  Time
 * out if no data can be written for a period of time to0, or if the complete
 * buffer has not been written after time to1.  If ${buflen} is zero, the
 * callback will be invoked with a status of NETWORK_STATUS_CLOSED, even if
 * the connection is still open.
 */
int
tsnetwork_write(int fd, const uint8_t * buf, size_t buflen,
    struct timeval * to0, struct timeval * to1,
    network_callback * callback, void * cookie)
{

	return (network_buf(fd, (uint8_t *)(uintptr_t)buf, buflen,
	    to0, to1, callback, cookie,
	    SEND, NETWORK_OP_WRITE, MSG_NOSIGNAL));
}