- stevesk@cvs.openbsd.org 2006/02/20 17:02:44

[openssh.git] / scp.c

/*
 * scp - secure remote copy.  This is basically patched BSD rcp which
 * uses ssh to do the data transfer (instead of using rcmd).
 *
 * NOTE: This version should NOT be suid root.  (This uses ssh to
 * do the transfer and ssh has the necessary privileges.)
 *
 * 1995 Timo Rinne <tri@iki.fi>, Tatu Ylonen <ylo@cs.hut.fi>
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */
/*
 * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
 * Copyright (c) 1999 Aaron Campbell.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Parts from:
 *
 * Copyright (c) 1983, 1990, 1992, 1993, 1995
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include "includes.h"
RCSID("$OpenBSD: scp.c,v 1.134 2006/02/20 17:19:54 stevesk Exp $");

#include <sys/types.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#include <sys/wait.h>

#include <dirent.h>

#include "xmalloc.h"
#include "atomicio.h"
#include "pathnames.h"
#include "log.h"
#include "misc.h"
#include "progressmeter.h"

extern char *__progname;

void bwlimit(int);

/* Struct for addargs */
arglist args;

/* Bandwidth limit */
off_t limit_rate = 0;

/* Name of current file being transferred. */
char *curfile;

/* This is set to non-zero to enable verbose mode. */
int verbose_mode = 0;

/* This is set to zero if the progressmeter is not desired. */
int showprogress = 1;

/* This is the program to execute for the secured connection. ("ssh" or -S) */
char *ssh_program = _PATH_SSH_PROGRAM;

/* This is used to store the pid of ssh_program */
pid_t do_cmd_pid = -1;

static void
killchild(int signo)
{
	if (do_cmd_pid > 1) {
		kill(do_cmd_pid, signo ? signo : SIGTERM);
		waitpid(do_cmd_pid, NULL, 0);
	}

	if (signo)
		_exit(1);
	exit(1);
}

static int
do_local_cmd(arglist *a)
{
	u_int i;
	int status;
	pid_t pid;

	if (a->num == 0)
		fatal("do_local_cmd: no arguments");

	if (verbose_mode) {
		fprintf(stderr, "Executing:");
		for (i = 0; i < a->num; i++)
			fprintf(stderr, " %s", a->list[i]);
		fprintf(stderr, "\n");
	}
	if ((pid = fork()) == -1)
		fatal("do_local_cmd: fork: %s", strerror(errno));

	if (pid == 0) {
		execvp(a->list[0], a->list);
		perror(a->list[0]);
		exit(1);
	}

	do_cmd_pid = pid;
	signal(SIGTERM, killchild);
	signal(SIGINT, killchild);
	signal(SIGHUP, killchild);

	while (waitpid(pid, &status, 0) == -1)
		if (errno != EINTR)
			fatal("do_local_cmd: waitpid: %s", strerror(errno));

	do_cmd_pid = -1;

	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
		return (-1);

	return (0);
}

/*
 * This function executes the given command as the specified user on the
 * given host.  This returns < 0 if execution fails, and >= 0 otherwise. This
 * assigns the input and output file descriptors on success.
 */

int
do_cmd(char *host, char *remuser, char *cmd, int *fdin, int *fdout, int argc)
{
	int pin[2], pout[2], reserved[2];

	if (verbose_mode)
		fprintf(stderr,
		    "Executing: program %s host %s, user %s, command %s\n",
		    ssh_program, host,
		    remuser ? remuser : "(unspecified)", cmd);

	/*
	 * Reserve two descriptors so that the real pipes won't get
	 * descriptors 0 and 1 because that will screw up dup2 below.
	 */
	pipe(reserved);

	/* Create a socket pair for communicating with ssh. */
	if (pipe(pin) < 0)
		fatal("pipe: %s", strerror(errno));
	if (pipe(pout) < 0)
		fatal("pipe: %s", strerror(errno));

	/* Free the reserved descriptors. */
	close(reserved[0]);
	close(reserved[1]);

	/* Fork a child to execute the command on the remote host using ssh. */
	do_cmd_pid = fork();
	if (do_cmd_pid == 0) {
		/* Child. */
		close(pin[1]);
		close(pout[0]);
		dup2(pin[0], 0);
		dup2(pout[1], 1);
		close(pin[0]);
		close(pout[1]);

		replacearg(&args, 0, "%s", ssh_program);
		if (remuser != NULL)
			addargs(&args, "-l%s", remuser);
		addargs(&args, "%s", host);
		addargs(&args, "%s", cmd);

		execvp(ssh_program, args.list);
		perror(ssh_program);
		exit(1);
	} else if (do_cmd_pid == -1) {
		fatal("fork: %s", strerror(errno));
	}
	/* Parent.  Close the other side, and return the local side. */
	close(pin[0]);
	*fdout = pin[1];
	close(pout[1]);
	*fdin = pout[0];
	signal(SIGTERM, killchild);
	signal(SIGINT, killchild);
	signal(SIGHUP, killchild);
	return 0;
}

typedef struct {
	size_t cnt;
	char *buf;
} BUF;

BUF *allocbuf(BUF *, int, int);
void lostconn(int);
void nospace(void);
int okname(char *);
void run_err(const char *,...);
void verifydir(char *);

struct passwd *pwd;
uid_t userid;
int errs, remin, remout;
int pflag, iamremote, iamrecursive, targetshouldbedirectory;

#define	CMDNEEDS	64
char cmd[CMDNEEDS];		/* must hold "rcp -r -p -d\0" */

int response(void);
void rsource(char *, struct stat *);
void sink(int, char *[]);
void source(int, char *[]);
void tolocal(int, char *[]);
void toremote(char *, int, char *[]);
void usage(void);

int
main(int argc, char **argv)
{
	int ch, fflag, tflag, status;
	double speed;
	char *targ, *endp;
	extern char *optarg;
	extern int optind;

	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
	sanitise_stdfd();

	__progname = ssh_get_progname(argv[0]);

	memset(&args, '\0', sizeof(args));
	args.list = NULL;
	addargs(&args, "%s", ssh_program);
	addargs(&args, "-x");
	addargs(&args, "-oForwardAgent no");
	addargs(&args, "-oPermitLocalCommand no");
	addargs(&args, "-oClearAllForwardings yes");

	fflag = tflag = 0;
	while ((ch = getopt(argc, argv, "dfl:prtvBCc:i:P:q1246S:o:F:")) != -1)
		switch (ch) {
		/* User-visible flags. */
		case '1':
		case '2':
		case '4':
		case '6':
		case 'C':
			addargs(&args, "-%c", ch);
			break;
		case 'o':
		case 'c':
		case 'i':
		case 'F':
			addargs(&args, "-%c%s", ch, optarg);
			break;
		case 'P':
			addargs(&args, "-p%s", optarg);
			break;
		case 'B':
			addargs(&args, "-oBatchmode yes");
			break;
		case 'l':
			speed = strtod(optarg, &endp);
			if (speed <= 0 || *endp != '\0')
				usage();
			limit_rate = speed * 1024;
			break;
		case 'p':
			pflag = 1;
			break;
		case 'r':
			iamrecursive = 1;
			break;
		case 'S':
			ssh_program = xstrdup(optarg);
			break;
		case 'v':
			addargs(&args, "-v");
			verbose_mode = 1;
			break;
		case 'q':
			addargs(&args, "-q");
			showprogress = 0;
			break;

		/* Server options. */
		case 'd':
			targetshouldbedirectory = 1;
			break;
		case 'f':	/* "from" */
			iamremote = 1;
			fflag = 1;
			break;
		case 't':	/* "to" */
			iamremote = 1;
			tflag = 1;
#ifdef HAVE_CYGWIN
			setmode(0, O_BINARY);
#endif
			break;
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if ((pwd = getpwuid(userid = getuid())) == NULL)
		fatal("unknown user %u", (u_int) userid);

	if (!isatty(STDERR_FILENO))
		showprogress = 0;

	remin = STDIN_FILENO;
	remout = STDOUT_FILENO;

	if (fflag) {
		/* Follow "protocol", send data. */
		(void) response();
		source(argc, argv);
		exit(errs != 0);
	}
	if (tflag) {
		/* Receive data. */
		sink(argc, argv);
		exit(errs != 0);
	}
	if (argc < 2)
		usage();
	if (argc > 2)
		targetshouldbedirectory = 1;

	remin = remout = -1;
	do_cmd_pid = -1;
	/* Command to be executed on remote system using "ssh". */
	(void) snprintf(cmd, sizeof cmd, "scp%s%s%s%s",
	    verbose_mode ? " -v" : "",
	    iamrecursive ? " -r" : "", pflag ? " -p" : "",
	    targetshouldbedirectory ? " -d" : "");

	(void) signal(SIGPIPE, lostconn);

	if ((targ = colon(argv[argc - 1])))	/* Dest is remote host. */
		toremote(targ, argc, argv);
	else {
		if (targetshouldbedirectory)
			verifydir(argv[argc - 1]);
		tolocal(argc, argv);	/* Dest is local host. */
	}
	/*
	 * Finally check the exit status of the ssh process, if one was forked
	 * and no error has occured yet
	 */
	if (do_cmd_pid != -1 && errs == 0) {
		if (remin != -1)
		    (void) close(remin);
		if (remout != -1)
		    (void) close(remout);
		if (waitpid(do_cmd_pid, &status, 0) == -1)
			errs = 1;
		else {
			if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
				errs = 1;
		}
	}
	exit(errs != 0);
}

void
toremote(char *targ, int argc, char **argv)
{
	int i, len;
	char *bp, *host, *src, *suser, *thost, *tuser, *arg;
	arglist alist;

	memset(&alist, '\0', sizeof(alist));
	alist.list = NULL;

	*targ++ = 0;
	if (*targ == 0)
		targ = ".";

	arg = xstrdup(argv[argc - 1]);
	if ((thost = strrchr(arg, '@'))) {
		/* user@host */
		*thost++ = 0;
		tuser = arg;
		if (*tuser == '\0')
			tuser = NULL;
	} else {
		thost = arg;
		tuser = NULL;
	}

	if (tuser != NULL && !okname(tuser)) {
		xfree(arg);
		return;
	}

	for (i = 0; i < argc - 1; i++) {
		src = colon(argv[i]);
		if (src) {	/* remote to remote */
			freeargs(&alist);
			addargs(&alist, "%s", ssh_program);
			if (verbose_mode)
				addargs(&alist, "-v");
			addargs(&alist, "-x");
			addargs(&alist, "-oClearAllForwardings yes");
			addargs(&alist, "-n");

			*src++ = 0;
			if (*src == 0)
				src = ".";
			host = strrchr(argv[i], '@');

			if (host) {
				*host++ = 0;
				host = cleanhostname(host);
				suser = argv[i];
				if (*suser == '\0')
					suser = pwd->pw_name;
				else if (!okname(suser))
					continue;
				addargs(&alist, "-l");
				addargs(&alist, "%s", suser);
			} else {
				host = cleanhostname(argv[i]);
			}
			addargs(&alist, "%s", host);
			addargs(&alist, "%s", cmd);
			addargs(&alist, "%s", src);
			addargs(&alist, "%s%s%s:%s",
			    tuser ? tuser : "", tuser ? "@" : "",
			    thost, targ);
			if (do_local_cmd(&alist) != 0)
				errs = 1;
		} else {	/* local to remote */
			if (remin == -1) {
				len = strlen(targ) + CMDNEEDS + 20;
				bp = xmalloc(len);
				(void) snprintf(bp, len, "%s -t %s", cmd, targ);
				host = cleanhostname(thost);
				if (do_cmd(host, tuser, bp, &remin,
				    &remout, argc) < 0)
					exit(1);
				if (response() < 0)
					exit(1);
				(void) xfree(bp);
			}
			source(1, argv + i);
		}
	}
}

void
tolocal(int argc, char **argv)
{
	int i, len;
	char *bp, *host, *src, *suser;
	arglist alist;

	memset(&alist, '\0', sizeof(alist));
	alist.list = NULL;

	for (i = 0; i < argc - 1; i++) {
		if (!(src = colon(argv[i]))) {	/* Local to local. */
			freeargs(&alist);
			addargs(&alist, "%s", _PATH_CP);
			if (iamrecursive)
				addargs(&alist, "-r");
			if (pflag)
				addargs(&alist, "-p");
			addargs(&alist, "%s", argv[i]);
			addargs(&alist, "%s", argv[argc-1]);
			if (do_local_cmd(&alist))
				++errs;
			continue;
		}
		*src++ = 0;
		if (*src == 0)
			src = ".";
		if ((host = strrchr(argv[i], '@')) == NULL) {
			host = argv[i];
			suser = NULL;
		} else {
			*host++ = 0;
			suser = argv[i];
			if (*suser == '\0')
				suser = pwd->pw_name;
		}
		host = cleanhostname(host);
		len = strlen(src) + CMDNEEDS + 20;
		bp = xmalloc(len);
		(void) snprintf(bp, len, "%s -f %s", cmd, src);
		if (do_cmd(host, suser, bp, &remin, &remout, argc) < 0) {
			(void) xfree(bp);
			++errs;
			continue;
		}
		xfree(bp);
		sink(1, argv + argc - 1);
		(void) close(remin);
		remin = remout = -1;
	}
}

void
source(int argc, char **argv)
{
	struct stat stb;
	static BUF buffer;
	BUF *bp;
	off_t i, amt, statbytes;
	size_t result;
	int fd = -1, haderr, indx;
	char *last, *name, buf[2048];
	int len;

	for (indx = 0; indx < argc; ++indx) {
		name = argv[indx];
		statbytes = 0;
		len = strlen(name);
		while (len > 1 && name[len-1] == '/')
			name[--len] = '\0';
		if (strchr(name, '\n') != NULL) {
			run_err("%s: skipping, filename contains a newline",
			    name);
			goto next;
		}
		if ((fd = open(name, O_RDONLY, 0)) < 0)
			goto syserr;
		if (fstat(fd, &stb) < 0) {
syserr:			run_err("%s: %s", name, strerror(errno));
			goto next;
		}
		switch (stb.st_mode & S_IFMT) {
		case S_IFREG:
			break;
		case S_IFDIR:
			if (iamrecursive) {
				rsource(name, &stb);
				goto next;
			}
			/* FALLTHROUGH */
		default:
			run_err("%s: not a regular file", name);
			goto next;
		}
		if ((last = strrchr(name, '/')) == NULL)
			last = name;
		else
			++last;
		curfile = last;
		if (pflag) {
			/*
			 * Make it compatible with possible future
			 * versions expecting microseconds.
			 */
			(void) snprintf(buf, sizeof buf, "T%lu 0 %lu 0\n",
			    (u_long) stb.st_mtime,
			    (u_long) stb.st_atime);
			(void) atomicio(vwrite, remout, buf, strlen(buf));
			if (response() < 0)
				goto next;
		}
#define	FILEMODEMASK	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
		snprintf(buf, sizeof buf, "C%04o %lld %s\n",
		    (u_int) (stb.st_mode & FILEMODEMASK),
		    (long long)stb.st_size, last);
		if (verbose_mode) {
			fprintf(stderr, "Sending file modes: %s", buf);
		}
		(void) atomicio(vwrite, remout, buf, strlen(buf));
		if (response() < 0)
			goto next;
		if ((bp = allocbuf(&buffer, fd, 2048)) == NULL) {
next:			if (fd != -1) {
				(void) close(fd);
				fd = -1;
			}
			continue;
		}
		if (showprogress)
			start_progress_meter(curfile, stb.st_size, &statbytes);
		/* Keep writing after an error so that we stay sync'd up. */
		for (haderr = i = 0; i < stb.st_size; i += bp->cnt) {
			amt = bp->cnt;
			if (i + amt > stb.st_size)
				amt = stb.st_size - i;
			if (!haderr) {
				result = atomicio(read, fd, bp->buf, amt);
				if (result != amt)
					haderr = errno;
			}
			if (haderr)
				(void) atomicio(vwrite, remout, bp->buf, amt);
			else {
				result = atomicio(vwrite, remout, bp->buf, amt);
				if (result != amt)
					haderr = errno;
				statbytes += result;
			}
			if (limit_rate)
				bwlimit(amt);
		}
		if (showprogress)
			stop_progress_meter();

		if (fd != -1) {
			if (close(fd) < 0 && !haderr)
				haderr = errno;
			fd = -1;
		}
		if (!haderr)
			(void) atomicio(vwrite, remout, "", 1);
		else
			run_err("%s: %s", name, strerror(haderr));
		(void) response();
	}
}

void
rsource(char *name, struct stat *statp)
{
	DIR *dirp;
	struct dirent *dp;
	char *last, *vect[1], path[1100];

	if (!(dirp = opendir(name))) {
		run_err("%s: %s", name, strerror(errno));
		return;
	}
	last = strrchr(name, '/');
	if (last == 0)
		last = name;
	else
		last++;
	if (pflag) {
		(void) snprintf(path, sizeof(path), "T%lu 0 %lu 0\n",
		    (u_long) statp->st_mtime,
		    (u_long) statp->st_atime);
		(void) atomicio(vwrite, remout, path, strlen(path));
		if (response() < 0) {
			closedir(dirp);
			return;
		}
	}
	(void) snprintf(path, sizeof path, "D%04o %d %.1024s\n",
	    (u_int) (statp->st_mode & FILEMODEMASK), 0, last);
	if (verbose_mode)
		fprintf(stderr, "Entering directory: %s", path);
	(void) atomicio(vwrite, remout, path, strlen(path));
	if (response() < 0) {
		closedir(dirp);
		return;
	}
	while ((dp = readdir(dirp)) != NULL) {
		if (dp->d_ino == 0)
			continue;
		if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, ".."))
			continue;
		if (strlen(name) + 1 + strlen(dp->d_name) >= sizeof(path) - 1) {
			run_err("%s/%s: name too long", name, dp->d_name);
			continue;
		}
		(void) snprintf(path, sizeof path, "%s/%s", name, dp->d_name);
		vect[0] = path;
		source(1, vect);
	}
	(void) closedir(dirp);
	(void) atomicio(vwrite, remout, "E\n", 2);
	(void) response();
}

void
bwlimit(int amount)
{
	static struct timeval bwstart, bwend;
	static int lamt, thresh = 16384;
	u_int64_t waitlen;
	struct timespec ts, rm;

	if (!timerisset(&bwstart)) {
		gettimeofday(&bwstart, NULL);
		return;
	}

	lamt += amount;
	if (lamt < thresh)
		return;

	gettimeofday(&bwend, NULL);
	timersub(&bwend, &bwstart, &bwend);
	if (!timerisset(&bwend))
		return;

	lamt *= 8;
	waitlen = (double)1000000L * lamt / limit_rate;

	bwstart.tv_sec = waitlen / 1000000L;
	bwstart.tv_usec = waitlen % 1000000L;

	if (timercmp(&bwstart, &bwend, >)) {
		timersub(&bwstart, &bwend, &bwend);

		/* Adjust the wait time */
		if (bwend.tv_sec) {
			thresh /= 2;
			if (thresh < 2048)
				thresh = 2048;
		} else if (bwend.tv_usec < 100) {
			thresh *= 2;
			if (thresh > 32768)
				thresh = 32768;
		}

		TIMEVAL_TO_TIMESPEC(&bwend, &ts);
		while (nanosleep(&ts, &rm) == -1) {
			if (errno != EINTR)
				break;
			ts = rm;
		}
	}

	lamt = 0;
	gettimeofday(&bwstart, NULL);
}

void
sink(int argc, char **argv)
{
	static BUF buffer;
	struct stat stb;
	enum {
		YES, NO, DISPLAYED
	} wrerr;
	BUF *bp;
	off_t i;
	size_t j, count;
	int amt, exists, first, mask, mode, ofd, omode;
	off_t size, statbytes;
	int setimes, targisdir, wrerrno = 0;
	char ch, *cp, *np, *targ, *why, *vect[1], buf[2048];
	struct timeval tv[2];

#define	atime	tv[0]
#define	mtime	tv[1]
#define	SCREWUP(str)	{ why = str; goto screwup; }

	setimes = targisdir = 0;
	mask = umask(0);
	if (!pflag)
		(void) umask(mask);
	if (argc != 1) {
		run_err("ambiguous target");
		exit(1);
	}
	targ = *argv;
	if (targetshouldbedirectory)
		verifydir(targ);

	(void) atomicio(vwrite, remout, "", 1);
	if (stat(targ, &stb) == 0 && S_ISDIR(stb.st_mode))
		targisdir = 1;
	for (first = 1;; first = 0) {
		cp = buf;
		if (atomicio(read, remin, cp, 1) != 1)
			return;
		if (*cp++ == '\n')
			SCREWUP("unexpected <newline>");
		do {
			if (atomicio(read, remin, &ch, sizeof(ch)) != sizeof(ch))
				SCREWUP("lost connection");
			*cp++ = ch;
		} while (cp < &buf[sizeof(buf) - 1] && ch != '\n');
		*cp = 0;
		if (verbose_mode)
			fprintf(stderr, "Sink: %s", buf);

		if (buf[0] == '\01' || buf[0] == '\02') {
			if (iamremote == 0)
				(void) atomicio(vwrite, STDERR_FILENO,
				    buf + 1, strlen(buf + 1));
			if (buf[0] == '\02')
				exit(1);
			++errs;
			continue;
		}
		if (buf[0] == 'E') {
			(void) atomicio(vwrite, remout, "", 1);
			return;
		}
		if (ch == '\n')
			*--cp = 0;

		cp = buf;
		if (*cp == 'T') {
			setimes++;
			cp++;
			mtime.tv_sec = strtol(cp, &cp, 10);
			if (!cp || *cp++ != ' ')
				SCREWUP("mtime.sec not delimited");
			mtime.tv_usec = strtol(cp, &cp, 10);
			if (!cp || *cp++ != ' ')
				SCREWUP("mtime.usec not delimited");
			atime.tv_sec = strtol(cp, &cp, 10);
			if (!cp || *cp++ != ' ')
				SCREWUP("atime.sec not delimited");
			atime.tv_usec = strtol(cp, &cp, 10);
			if (!cp || *cp++ != '\0')
				SCREWUP("atime.usec not delimited");
			(void) atomicio(vwrite, remout, "", 1);
			continue;
		}
		if (*cp != 'C' && *cp != 'D') {
			/*
			 * Check for the case "rcp remote:foo\* local:bar".
			 * In this case, the line "No match." can be returned
			 * by the shell before the rcp command on the remote is
			 * executed so the ^Aerror_message convention isn't
			 * followed.
			 */
			if (first) {
				run_err("%s", cp);
				exit(1);
			}
			SCREWUP("expected control record");
		}
		mode = 0;
		for (++cp; cp < buf + 5; cp++) {
			if (*cp < '0' || *cp > '7')
				SCREWUP("bad mode");
			mode = (mode << 3) | (*cp - '0');
		}
		if (*cp++ != ' ')
			SCREWUP("mode not delimited");

		for (size = 0; isdigit(*cp);)
			size = size * 10 + (*cp++ - '0');
		if (*cp++ != ' ')
			SCREWUP("size not delimited");
		if ((strchr(cp, '/') != NULL) || (strcmp(cp, "..") == 0)) {
			run_err("error: unexpected filename: %s", cp);
			exit(1);
		}
		if (targisdir) {
			static char *namebuf;
			static size_t cursize;
			size_t need;

			need = strlen(targ) + strlen(cp) + 250;
			if (need > cursize) {
				if (namebuf)
					xfree(namebuf);
				namebuf = xmalloc(need);
				cursize = need;
			}
			(void) snprintf(namebuf, need, "%s%s%s", targ,
			    strcmp(targ, "/") ? "/" : "", cp);
			np = namebuf;
		} else
			np = targ;
		curfile = cp;
		exists = stat(np, &stb) == 0;
		if (buf[0] == 'D') {
			int mod_flag = pflag;
			if (!iamrecursive)
				SCREWUP("received directory without -r");
			if (exists) {
				if (!S_ISDIR(stb.st_mode)) {
					errno = ENOTDIR;
					goto bad;
				}
				if (pflag)
					(void) chmod(np, mode);
			} else {
				/* Handle copying from a read-only
				   directory */
				mod_flag = 1;
				if (mkdir(np, mode | S_IRWXU) < 0)
					goto bad;
			}
			vect[0] = xstrdup(np);
			sink(1, vect);
			if (setimes) {
				setimes = 0;
				if (utimes(vect[0], tv) < 0)
					run_err("%s: set times: %s",
					    vect[0], strerror(errno));
			}
			if (mod_flag)
				(void) chmod(vect[0], mode);
			if (vect[0])
				xfree(vect[0]);
			continue;
		}
		omode = mode;
		mode |= S_IWRITE;
		if ((ofd = open(np, O_WRONLY|O_CREAT, mode)) < 0) {
bad:			run_err("%s: %s", np, strerror(errno));
			continue;
		}
		(void) atomicio(vwrite, remout, "", 1);
		if ((bp = allocbuf(&buffer, ofd, 4096)) == NULL) {
			(void) close(ofd);
			continue;
		}
		cp = bp->buf;
		wrerr = NO;

		statbytes = 0;
		if (showprogress)
			start_progress_meter(curfile, size, &statbytes);
		for (count = i = 0; i < size; i += 4096) {
			amt = 4096;
			if (i + amt > size)
				amt = size - i;
			count += amt;
			do {
				j = atomicio(read, remin, cp, amt);
				if (j == 0) {
					run_err("%s", j ? strerror(errno) :
					    "dropped connection");
					exit(1);
				}
				amt -= j;
				cp += j;
				statbytes += j;
			} while (amt > 0);

			if (limit_rate)
				bwlimit(4096);

			if (count == bp->cnt) {
				/* Keep reading so we stay sync'd up. */
				if (wrerr == NO) {
					if (atomicio(vwrite, ofd, bp->buf,
					    count) != count) {
						wrerr = YES;
						wrerrno = errno;
					}
				}
				count = 0;
				cp = bp->buf;
			}
		}
		if (showprogress)
			stop_progress_meter();
		if (count != 0 && wrerr == NO &&
		    atomicio(vwrite, ofd, bp->buf, count) != count) {
			wrerr = YES;
			wrerrno = errno;
		}
		if (wrerr == NO && ftruncate(ofd, size) != 0) {
			run_err("%s: truncate: %s", np, strerror(errno));
			wrerr = DISPLAYED;
		}
		if (pflag) {
			if (exists || omode != mode)
#ifdef HAVE_FCHMOD
				if (fchmod(ofd, omode)) {
#else /* HAVE_FCHMOD */
				if (chmod(np, omode)) {
#endif /* HAVE_FCHMOD */
					run_err("%s: set mode: %s",
					    np, strerror(errno));
					wrerr = DISPLAYED;
				}
		} else {
			if (!exists && omode != mode)
#ifdef HAVE_FCHMOD
				if (fchmod(ofd, omode & ~mask)) {
#else /* HAVE_FCHMOD */
				if (chmod(np, omode & ~mask)) {
#endif /* HAVE_FCHMOD */
					run_err("%s: set mode: %s",
					    np, strerror(errno));
					wrerr = DISPLAYED;
				}
		}
		if (close(ofd) == -1) {
			wrerr = YES;
			wrerrno = errno;
		}
		(void) response();
		if (setimes && wrerr == NO) {
			setimes = 0;
			if (utimes(np, tv) < 0) {
				run_err("%s: set times: %s",
				    np, strerror(errno));
				wrerr = DISPLAYED;
			}
		}
		switch (wrerr) {
		case YES:
			run_err("%s: %s", np, strerror(wrerrno));
			break;
		case NO:
			(void) atomicio(vwrite, remout, "", 1);
			break;
		case DISPLAYED:
			break;
		}
	}
screwup:
	run_err("protocol error: %s", why);
	exit(1);
}

int
response(void)
{
	char ch, *cp, resp, rbuf[2048];

	if (atomicio(read, remin, &resp, sizeof(resp)) != sizeof(resp))
		lostconn(0);

	cp = rbuf;
	switch (resp) {
	case 0:		/* ok */
		return (0);
	default:
		*cp++ = resp;
		/* FALLTHROUGH */
	case 1:		/* error, followed by error msg */
	case 2:		/* fatal error, "" */
		do {
			if (atomicio(read, remin, &ch, sizeof(ch)) != sizeof(ch))
				lostconn(0);
			*cp++ = ch;
		} while (cp < &rbuf[sizeof(rbuf) - 1] && ch != '\n');

		if (!iamremote)
			(void) atomicio(vwrite, STDERR_FILENO, rbuf, cp - rbuf);
		++errs;
		if (resp == 1)
			return (-1);
		exit(1);
	}
	/* NOTREACHED */
}

void
usage(void)
{
	(void) fprintf(stderr,
	    "usage: scp [-1246BCpqrv] [-c cipher] [-F ssh_config] [-i identity_file]\n"
	    "           [-l limit] [-o ssh_option] [-P port] [-S program]\n"
	    "           [[user@]host1:]file1 [...] [[user@]host2:]file2\n");
	exit(1);
}

void
run_err(const char *fmt,...)
{
	static FILE *fp;
	va_list ap;

	++errs;
	if (fp == NULL && !(fp = fdopen(remout, "w")))
		return;
	(void) fprintf(fp, "%c", 0x01);
	(void) fprintf(fp, "scp: ");
	va_start(ap, fmt);
	(void) vfprintf(fp, fmt, ap);
	va_end(ap);
	(void) fprintf(fp, "\n");
	(void) fflush(fp);

	if (!iamremote) {
		va_start(ap, fmt);
		vfprintf(stderr, fmt, ap);
		va_end(ap);
		fprintf(stderr, "\n");
	}
}

void
verifydir(char *cp)
{
	struct stat stb;

	if (!stat(cp, &stb)) {
		if (S_ISDIR(stb.st_mode))
			return;
		errno = ENOTDIR;
	}
	run_err("%s: %s", cp, strerror(errno));
	killchild(0);
}

int
okname(char *cp0)
{
	int c;
	char *cp;

	cp = cp0;
	do {
		c = (int)*cp;
		if (c & 0200)
			goto bad;
		if (!isalpha(c) && !isdigit(c)) {
			switch (c) {
			case '\'':
			case '"':
			case '`':
			case ' ':
			case '#':
				goto bad;
			default:
				break;
			}
		}
	} while (*++cp);
	return (1);

bad:	fprintf(stderr, "%s: invalid user name\n", cp0);
	return (0);
}

BUF *
allocbuf(BUF *bp, int fd, int blksize)
{
	size_t size;
#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
	struct stat stb;

	if (fstat(fd, &stb) < 0) {
		run_err("fstat: %s", strerror(errno));
		return (0);
	}
	size = roundup(stb.st_blksize, blksize);
	if (size == 0)
		size = blksize;
#else /* HAVE_STRUCT_STAT_ST_BLKSIZE */
	size = blksize;
#endif /* HAVE_STRUCT_STAT_ST_BLKSIZE */
	if (bp->cnt >= size)
		return (bp);
	if (bp->buf == NULL)
		bp->buf = xmalloc(size);
	else
		bp->buf = xrealloc(bp->buf, size);
	memset(bp->buf, 0, size);
	bp->cnt = size;
	return (bp);
}

void
lostconn(int signo)
{
	if (!iamremote)
		write(STDERR_FILENO, "lost connection\n", 16);
	if (signo)
		_exit(1);
	else
		exit(1);
}