A major purpose of PuTTY's memory-allocation functions is to succeed or die

[u/mdw/putty] / pscp.c

/*
 * scp.c  -  Scp (Secure Copy) client for PuTTY.
 * Joris van Rantwijk, Simon Tatham
 *
 * This is mainly based on ssh-1.2.26/scp.c by Timo Rinne & Tatu Ylonen.
 * They, in turn, used stuff from BSD rcp.
 * 
 * (SGT, 2001-09-10: Joris van Rantwijk assures me that although
 * this file as originally submitted was inspired by, and
 * _structurally_ based on, ssh-1.2.26's scp.c, there wasn't any
 * actual code duplicated, so the above comment shouldn't give rise
 * to licensing issues.)
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <time.h>
#include <assert.h>

#define PUTTY_DO_GLOBALS
#include "putty.h"
#include "psftp.h"
#include "ssh.h"
#include "sftp.h"
#include "storage.h"

static int list = 0;
static int verbose = 0;
static int recursive = 0;
static int preserve = 0;
static int targetshouldbedirectory = 0;
static int statistics = 1;
static int prev_stats_len = 0;
static int scp_unsafe_mode = 0;
static int errs = 0;
static int gui_mode = 0;
static int try_scp = 1;
static int try_sftp = 1;
static int main_cmd_is_sftp = 0;
static int fallback_cmd_is_sftp = 0;
static int using_sftp = 0;

static Backend *back;
static void *backhandle;
static Config cfg;

static void source(char *src);
static void rsource(char *src);
static void sink(char *targ, char *src);

/*
 * The maximum amount of queued data we accept before we stop and
 * wait for the server to process some.
 */
#define MAX_SCP_BUFSIZE 16384

void ldisc_send(void *handle, char *buf, int len, int interactive)
{
    /*
     * This is only here because of the calls to ldisc_send(NULL,
     * 0) in ssh.c. Nothing in PSCP actually needs to use the ldisc
     * as an ldisc. So if we get called with any real data, I want
     * to know about it.
     */
    assert(len == 0);
}

static void tell_char(FILE * stream, char c)
{
    if (!gui_mode)
        fputc(c, stream);
    else
        gui_send_char(stream == stderr, c);
}

static void tell_str(FILE * stream, char *str)
{
    unsigned int i;

    for (i = 0; i < strlen(str); ++i)
        tell_char(stream, str[i]);
}

static void tell_user(FILE * stream, char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    str = dupvprintf(fmt, ap);
    va_end(ap);
    str2 = dupcat(str, "\n", NULL);
    sfree(str);
    tell_str(stream, str2);
    sfree(str2);
}

/*
 *  Print an error message and perform a fatal exit.
 */
void fatalbox(char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    str = dupvprintf(fmt, ap);
    str2 = dupcat("Fatal: ", str, "\n", NULL);
    sfree(str);
    va_end(ap);
    tell_str(stderr, str2);
    sfree(str2);
    errs++;

    if (gui_mode)
        gui_send_errcount(list, errs);

    cleanup_exit(1);
}
void modalfatalbox(char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    str = dupvprintf(fmt, ap);
    str2 = dupcat("Fatal: ", str, "\n", NULL);
    sfree(str);
    va_end(ap);
    tell_str(stderr, str2);
    sfree(str2);
    errs++;

    if (gui_mode)
        gui_send_errcount(list, errs);

    cleanup_exit(1);
}
void connection_fatal(void *frontend, char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    str = dupvprintf(fmt, ap);
    str2 = dupcat("Fatal: ", str, "\n", NULL);
    sfree(str);
    va_end(ap);
    tell_str(stderr, str2);
    sfree(str2);
    errs++;

    if (gui_mode)
        gui_send_errcount(list, errs);

    cleanup_exit(1);
}

/*
 * In pscp, all agent requests should be synchronous, so this is a
 * never-called stub.
 */
void agent_schedule_callback(void (*callback)(void *, void *, int),
                             void *callback_ctx, void *data, int len)
{
    assert(!"We shouldn't be here");
}

/*
 * Receive a block of data from the SSH link. Block until all data
 * is available.
 *
 * To do this, we repeatedly call the SSH protocol module, with our
 * own trap in from_backend() to catch the data that comes back. We
 * do this until we have enough data.
 */

static unsigned char *outptr;          /* where to put the data */
static unsigned outlen;                /* how much data required */
static unsigned char *pending = NULL;  /* any spare data */
static unsigned pendlen = 0, pendsize = 0;      /* length and phys. size of buffer */
int from_backend(void *frontend, int is_stderr, const char *data, int datalen)
{
    unsigned char *p = (unsigned char *) data;
    unsigned len = (unsigned) datalen;

    /*
     * stderr data is just spouted to local stderr and otherwise
     * ignored.
     */
    if (is_stderr) {
        if (len > 0)
            fwrite(data, 1, len, stderr);
        return 0;
    }

    /*
     * If this is before the real session begins, just return.
     */
    if (!outptr)
        return 0;

    if ((outlen > 0) && (len > 0)) {
        unsigned used = outlen;
        if (used > len)
            used = len;
        memcpy(outptr, p, used);
        outptr += used;
        outlen -= used;
        p += used;
        len -= used;
    }

    if (len > 0) {
        if (pendsize < pendlen + len) {
            pendsize = pendlen + len + 4096;
            pending = sresize(pending, pendsize, unsigned char);
        }
        memcpy(pending + pendlen, p, len);
        pendlen += len;
    }

    return 0;
}
static int ssh_scp_recv(unsigned char *buf, int len)
{
    outptr = buf;
    outlen = len;

    /*
     * See if the pending-input block contains some of what we
     * need.
     */
    if (pendlen > 0) {
        unsigned pendused = pendlen;
        if (pendused > outlen)
            pendused = outlen;
        memcpy(outptr, pending, pendused);
        memmove(pending, pending + pendused, pendlen - pendused);
        outptr += pendused;
        outlen -= pendused;
        pendlen -= pendused;
        if (pendlen == 0) {
            pendsize = 0;
            sfree(pending);
            pending = NULL;
        }
        if (outlen == 0)
            return len;
    }

    while (outlen > 0) {
        if (ssh_sftp_loop_iteration() < 0)
            return 0;                  /* doom */
    }

    return len;
}

/*
 * Loop through the ssh connection and authentication process.
 */
static void ssh_scp_init(void)
{
    while (!back->sendok(backhandle)) {
        if (ssh_sftp_loop_iteration() < 0)
            return;                    /* doom */
    }

    /* Work out which backend we ended up using. */
    if (!ssh_fallback_cmd(backhandle))
        using_sftp = main_cmd_is_sftp;
    else
        using_sftp = fallback_cmd_is_sftp;

    if (verbose) {
        if (using_sftp)
            tell_user(stderr, "Using SFTP");
        else
            tell_user(stderr, "Using SCP1");
    }
}

/*
 *  Print an error message and exit after closing the SSH link.
 */
static void bump(char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    str = dupvprintf(fmt, ap);
    va_end(ap);
    str2 = dupcat(str, "\n", NULL);
    sfree(str);
    tell_str(stderr, str2);
    sfree(str2);
    errs++;

    if (back != NULL && back->socket(backhandle) != NULL) {
        char ch;
        back->special(backhandle, TS_EOF);
        ssh_scp_recv((unsigned char *) &ch, 1);
    }

    if (gui_mode)
        gui_send_errcount(list, errs);

    cleanup_exit(1);
}

/*
 *  Open an SSH connection to user@host and execute cmd.
 */
static void do_cmd(char *host, char *user, char *cmd)
{
    const char *err;
    char *realhost;
    void *logctx;

    if (host == NULL || host[0] == '\0')
        bump("Empty host name");

    /*
     * Remove fiddly bits of address: remove a colon suffix, and
     * the square brackets around an IPv6 literal address.
     */
    if (host[0] == '[') {
        host++;
        host[strcspn(host, "]")] = '\0';
    } else {
        host[strcspn(host, ":")] = '\0';
    }

    /*
     * If we haven't loaded session details already (e.g., from -load),
     * try looking for a session called "host".
     */
    if (!loaded_session) {
        /* Try to load settings for `host' into a temporary config */
        Config cfg2;
        cfg2.host[0] = '\0';
        do_defaults(host, &cfg2);
        if (cfg2.host[0] != '\0') {
            /* Settings present and include hostname */
            /* Re-load data into the real config. */
            do_defaults(host, &cfg);
        } else {
            /* Session doesn't exist or mention a hostname. */
            /* Use `host' as a bare hostname. */
            strncpy(cfg.host, host, sizeof(cfg.host) - 1);
            cfg.host[sizeof(cfg.host) - 1] = '\0';
        }
    } else {
        /* Patch in hostname `host' to session details. */
        strncpy(cfg.host, host, sizeof(cfg.host) - 1);
        cfg.host[sizeof(cfg.host) - 1] = '\0';
    }

    /*
     * Force use of SSH. (If they got the protocol wrong we assume the
     * port is useless too.)
     */
    if (cfg.protocol != PROT_SSH) {
        cfg.protocol = PROT_SSH;
        cfg.port = 22;
    }

    /*
     * Enact command-line overrides.
     */
    cmdline_run_saved(&cfg);

    /*
     * Trim leading whitespace off the hostname if it's there.
     */
    {
        int space = strspn(cfg.host, " \t");
        memmove(cfg.host, cfg.host+space, 1+strlen(cfg.host)-space);
    }

    /* See if host is of the form user@host */
    if (cfg.host[0] != '\0') {
        char *atsign = strrchr(cfg.host, '@');
        /* Make sure we're not overflowing the user field */
        if (atsign) {
            if (atsign - cfg.host < sizeof cfg.username) {
                strncpy(cfg.username, cfg.host, atsign - cfg.host);
                cfg.username[atsign - cfg.host] = '\0';
            }
            memmove(cfg.host, atsign + 1, 1 + strlen(atsign + 1));
        }
    }

    /*
     * Remove any remaining whitespace from the hostname.
     */
    {
        int p1 = 0, p2 = 0;
        while (cfg.host[p2] != '\0') {
            if (cfg.host[p2] != ' ' && cfg.host[p2] != '\t') {
                cfg.host[p1] = cfg.host[p2];
                p1++;
            }
            p2++;
        }
        cfg.host[p1] = '\0';
    }

    /* Set username */
    if (user != NULL && user[0] != '\0') {
        strncpy(cfg.username, user, sizeof(cfg.username) - 1);
        cfg.username[sizeof(cfg.username) - 1] = '\0';
    } else if (cfg.username[0] == '\0') {
        user = get_username();
        if (!user)
            bump("Empty user name");
        else {
            if (verbose)
                tell_user(stderr, "Guessing user name: %s", user);
            strncpy(cfg.username, user, sizeof(cfg.username) - 1);
            cfg.username[sizeof(cfg.username) - 1] = '\0';
            sfree(user);
        }
    }

    /*
     * Disable scary things which shouldn't be enabled for simple
     * things like SCP and SFTP: agent forwarding, port forwarding,
     * X forwarding.
     */
    cfg.x11_forward = 0;
    cfg.agentfwd = 0;
    cfg.portfwd[0] = cfg.portfwd[1] = '\0';

    /*
     * Set up main and possibly fallback command depending on
     * options specified by user.
     * Attempt to start the SFTP subsystem as a first choice,
     * falling back to the provided scp command if that fails.
     */
    cfg.remote_cmd_ptr2 = NULL;
    if (try_sftp) {
        /* First choice is SFTP subsystem. */
        main_cmd_is_sftp = 1;
        strcpy(cfg.remote_cmd, "sftp");
        cfg.ssh_subsys = TRUE;
        if (try_scp) {
            /* Fallback is to use the provided scp command. */
            fallback_cmd_is_sftp = 0;
            cfg.remote_cmd_ptr2 = cmd;
            cfg.ssh_subsys2 = FALSE;
        } else {
            /* Since we're not going to try SCP, we may as well try
             * harder to find an SFTP server, since in the current
             * implementation we have a spare slot. */
            fallback_cmd_is_sftp = 1;
            /* see psftp.c for full explanation of this kludge */
            cfg.remote_cmd_ptr2 = 
                "test -x /usr/lib/sftp-server && exec /usr/lib/sftp-server\n"
                "test -x /usr/local/lib/sftp-server && exec /usr/local/lib/sftp-server\n"
                "exec sftp-server";
            cfg.ssh_subsys2 = FALSE;
        }
    } else {
        /* Don't try SFTP at all; just try the scp command. */
        main_cmd_is_sftp = 0;
        cfg.remote_cmd_ptr = cmd;
        cfg.ssh_subsys = FALSE;
    }
    cfg.nopty = TRUE;

    back = &ssh_backend;

    err = back->init(NULL, &backhandle, &cfg, cfg.host, cfg.port, &realhost, 
                     0, cfg.tcp_keepalives);
    if (err != NULL)
        bump("ssh_init: %s", err);
    logctx = log_init(NULL, &cfg);
    back->provide_logctx(backhandle, logctx);
    console_provide_logctx(logctx);
    ssh_scp_init();
    if (verbose && realhost != NULL)
        tell_user(stderr, "Connected to %s\n", realhost);
    sfree(realhost);
}

/*
 *  Update statistic information about current file.
 */
static void print_stats(char *name, unsigned long size, unsigned long done,
                        time_t start, time_t now)
{
    float ratebs;
    unsigned long eta;
    char *etastr;
    int pct;
    int len;
    int elap;

    elap = (unsigned long) difftime(now, start);

    if (now > start)
        ratebs = (float) done / elap;
    else
        ratebs = (float) done;

    if (ratebs < 1.0)
        eta = size - done;
    else
        eta = (unsigned long) ((size - done) / ratebs);
    etastr = dupprintf("%02ld:%02ld:%02ld",
                       eta / 3600, (eta % 3600) / 60, eta % 60);

    pct = (int) (100 * (done * 1.0 / size));

    if (gui_mode) {
        gui_update_stats(name, size, pct, elap, done, eta,
                         (unsigned long) ratebs);
    } else {
        len = printf("\r%-25.25s | %10ld kB | %5.1f kB/s | ETA: %8s | %3d%%",
                     name, done / 1024, ratebs / 1024.0, etastr, pct);
        if (len < prev_stats_len)
            printf("%*s", prev_stats_len - len, "");
        prev_stats_len = len;

        if (done == size)
            printf("\n");

        fflush(stdout);
    }

    free(etastr);
}

/*
 *  Find a colon in str and return a pointer to the colon.
 *  This is used to separate hostname from filename.
 */
static char *colon(char *str)
{
    /* Check and process IPv6 literal addresses
     * (eg: 'jeroen@[2001:db8::1]:myfile.txt') */
    char *ipv6 = strchr(str, '[');
    if (ipv6) {
        str = strchr(str, ']');
        if (str) {
            /* Terminate on the closing bracket */
            *str++ = '\0';
            return (str);
        }
        return (NULL);
    }

    /* We ignore a leading colon, since the hostname cannot be
       empty. We also ignore a colon as second character because
       of filenames like f:myfile.txt. */
    if (str[0] == '\0' || str[0] == ':' || str[1] == ':')
        return (NULL);
    while (*str != '\0' && *str != ':' && *str != '/' && *str != '\\')
        str++;
    if (*str == ':')
        return (str);
    else
        return (NULL);
}

/*
 * Return a pointer to the portion of str that comes after the last
 * slash (or backslash or colon, if `local' is TRUE).
 */
static char *stripslashes(char *str, int local)
{
    char *p;

    if (local) {
        p = strchr(str, ':');
        if (p) str = p+1;
    }

    p = strrchr(str, '/');
    if (p) str = p+1;

    if (local) {
        p = strrchr(str, '\\');
        if (p) str = p+1;
    }

    return str;
}

/*
 * Determine whether a string is entirely composed of dots.
 */
static int is_dots(char *str)
{
    return str[strspn(str, ".")] == '\0';
}

/*
 *  Wait for a response from the other side.
 *  Return 0 if ok, -1 if error.
 */
static int response(void)
{
    char ch, resp, rbuf[2048];
    int p;

    if (ssh_scp_recv((unsigned char *) &resp, 1) <= 0)
        bump("Lost connection");

    p = 0;
    switch (resp) {
      case 0:                          /* ok */
        return (0);
      default:
        rbuf[p++] = resp;
        /* fallthrough */
      case 1:                          /* error */
      case 2:                          /* fatal error */
        do {
            if (ssh_scp_recv((unsigned char *) &ch, 1) <= 0)
                bump("Protocol error: Lost connection");
            rbuf[p++] = ch;
        } while (p < sizeof(rbuf) && ch != '\n');
        rbuf[p - 1] = '\0';
        if (resp == 1)
            tell_user(stderr, "%s\n", rbuf);
        else
            bump("%s", rbuf);
        errs++;
        return (-1);
    }
}

int sftp_recvdata(char *buf, int len)
{
    return ssh_scp_recv((unsigned char *) buf, len);
}
int sftp_senddata(char *buf, int len)
{
    back->send(backhandle, buf, len);
    return 1;
}

/* ----------------------------------------------------------------------
 * sftp-based replacement for the hacky `pscp -ls'.
 */
static int sftp_ls_compare(const void *av, const void *bv)
{
    const struct fxp_name *a = (const struct fxp_name *) av;
    const struct fxp_name *b = (const struct fxp_name *) bv;
    return strcmp(a->filename, b->filename);
}
void scp_sftp_listdir(char *dirname)
{
    struct fxp_handle *dirh;
    struct fxp_names *names;
    struct fxp_name *ournames;
    struct sftp_packet *pktin;
    struct sftp_request *req, *rreq;
    int nnames, namesize;
    int i;

    if (!fxp_init()) {
        tell_user(stderr, "unable to initialise SFTP: %s", fxp_error());
        errs++;
        return;
    }

    printf("Listing directory %s\n", dirname);

    sftp_register(req = fxp_opendir_send(dirname));
    rreq = sftp_find_request(pktin = sftp_recv());
    assert(rreq == req);
    dirh = fxp_opendir_recv(pktin, rreq);

    if (dirh == NULL) {
        printf("Unable to open %s: %s\n", dirname, fxp_error());
    } else {
        nnames = namesize = 0;
        ournames = NULL;

        while (1) {

            sftp_register(req = fxp_readdir_send(dirh));
            rreq = sftp_find_request(pktin = sftp_recv());
            assert(rreq == req);
            names = fxp_readdir_recv(pktin, rreq);

            if (names == NULL) {
                if (fxp_error_type() == SSH_FX_EOF)
                    break;
                printf("Reading directory %s: %s\n", dirname, fxp_error());
                break;
            }
            if (names->nnames == 0) {
                fxp_free_names(names);
                break;
            }

            if (nnames + names->nnames >= namesize) {
                namesize += names->nnames + 128;
                ournames = sresize(ournames, namesize, struct fxp_name);
            }

            for (i = 0; i < names->nnames; i++)
                ournames[nnames++] = names->names[i];
            names->nnames = 0;         /* prevent free_names */
            fxp_free_names(names);
        }
        sftp_register(req = fxp_close_send(dirh));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        fxp_close_recv(pktin, rreq);

        /*
         * Now we have our filenames. Sort them by actual file
         * name, and then output the longname parts.
         */
        qsort(ournames, nnames, sizeof(*ournames), sftp_ls_compare);

        /*
         * And print them.
         */
        for (i = 0; i < nnames; i++)
            printf("%s\n", ournames[i].longname);
    }
}

/* ----------------------------------------------------------------------
 * Helper routines that contain the actual SCP protocol elements,
 * implemented both as SCP1 and SFTP.
 */

static struct scp_sftp_dirstack {
    struct scp_sftp_dirstack *next;
    struct fxp_name *names;
    int namepos, namelen;
    char *dirpath;
    char *wildcard;
    int matched_something;             /* wildcard match set was non-empty */
} *scp_sftp_dirstack_head;
static char *scp_sftp_remotepath, *scp_sftp_currentname;
static char *scp_sftp_wildcard;
static int scp_sftp_targetisdir, scp_sftp_donethistarget;
static int scp_sftp_preserve, scp_sftp_recursive;
static unsigned long scp_sftp_mtime, scp_sftp_atime;
static int scp_has_times;
static struct fxp_handle *scp_sftp_filehandle;
static struct fxp_xfer *scp_sftp_xfer;
static uint64 scp_sftp_fileoffset;

void scp_source_setup(char *target, int shouldbedir)
{
    if (using_sftp) {
        /*
         * Find out whether the target filespec is in fact a
         * directory.
         */
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;
        struct fxp_attrs attrs;
        int ret;

        if (!fxp_init()) {
            tell_user(stderr, "unable to initialise SFTP: %s", fxp_error());
            errs++;
            return;
        }

        sftp_register(req = fxp_stat_send(target));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        ret = fxp_stat_recv(pktin, rreq, &attrs);

        if (!ret || !(attrs.flags & SSH_FILEXFER_ATTR_PERMISSIONS))
            scp_sftp_targetisdir = 0;
        else
            scp_sftp_targetisdir = (attrs.permissions & 0040000) != 0;

        if (shouldbedir && !scp_sftp_targetisdir) {
            bump("pscp: remote filespec %s: not a directory\n", target);
        }

        scp_sftp_remotepath = dupstr(target);

        scp_has_times = 0;
    } else {
        (void) response();
    }
}

int scp_send_errmsg(char *str)
{
    if (using_sftp) {
        /* do nothing; we never need to send our errors to the server */
    } else {
        back->send(backhandle, "\001", 1);/* scp protocol error prefix */
        back->send(backhandle, str, strlen(str));
    }
    return 0;                          /* can't fail */
}

int scp_send_filetimes(unsigned long mtime, unsigned long atime)
{
    if (using_sftp) {
        scp_sftp_mtime = mtime;
        scp_sftp_atime = atime;
        scp_has_times = 1;
        return 0;
    } else {
        char buf[80];
        sprintf(buf, "T%lu 0 %lu 0\n", mtime, atime);
        back->send(backhandle, buf, strlen(buf));
        return response();
    }
}

int scp_send_filename(char *name, unsigned long size, int modes)
{
    if (using_sftp) {
        char *fullname;
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;

        if (scp_sftp_targetisdir) {
            fullname = dupcat(scp_sftp_remotepath, "/", name, NULL);
        } else {
            fullname = dupstr(scp_sftp_remotepath);
        }

        sftp_register(req = fxp_open_send(fullname, SSH_FXF_WRITE |
                                          SSH_FXF_CREAT | SSH_FXF_TRUNC));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        scp_sftp_filehandle = fxp_open_recv(pktin, rreq);

        if (!scp_sftp_filehandle) {
            tell_user(stderr, "pscp: unable to open %s: %s",
                      fullname, fxp_error());
            errs++;
            return 1;
        }
        scp_sftp_fileoffset = uint64_make(0, 0);
        scp_sftp_xfer = xfer_upload_init(scp_sftp_filehandle,
                                         scp_sftp_fileoffset);
        sfree(fullname);
        return 0;
    } else {
        char buf[40];
        sprintf(buf, "C%04o %lu ", modes, size);
        back->send(backhandle, buf, strlen(buf));
        back->send(backhandle, name, strlen(name));
        back->send(backhandle, "\n", 1);
        return response();
    }
}

int scp_send_filedata(char *data, int len)
{
    if (using_sftp) {
        int ret;
        struct sftp_packet *pktin;

        if (!scp_sftp_filehandle) {
            return 1;
        }

        while (!xfer_upload_ready(scp_sftp_xfer)) {
            pktin = sftp_recv();
            ret = xfer_upload_gotpkt(scp_sftp_xfer, pktin);
            if (!ret) {
                tell_user(stderr, "error while writing: %s\n", fxp_error());
                errs++;
                return 1;
            }
        }

        xfer_upload_data(scp_sftp_xfer, data, len);

        scp_sftp_fileoffset = uint64_add32(scp_sftp_fileoffset, len);
        return 0;
    } else {
        int bufsize = back->send(backhandle, data, len);

        /*
         * If the network transfer is backing up - that is, the
         * remote site is not accepting data as fast as we can
         * produce it - then we must loop on network events until
         * we have space in the buffer again.
         */
        while (bufsize > MAX_SCP_BUFSIZE) {
            if (ssh_sftp_loop_iteration() < 0)
                return 1;
            bufsize = back->sendbuffer(backhandle);
        }

        return 0;
    }
}

int scp_send_finish(void)
{
    if (using_sftp) {
        struct fxp_attrs attrs;
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;
        int ret;

        while (!xfer_done(scp_sftp_xfer)) {
            pktin = sftp_recv();
            xfer_upload_gotpkt(scp_sftp_xfer, pktin);
        }
        xfer_cleanup(scp_sftp_xfer);

        if (!scp_sftp_filehandle) {
            return 1;
        }
        if (scp_has_times) {
            attrs.flags = SSH_FILEXFER_ATTR_ACMODTIME;
            attrs.atime = scp_sftp_atime;
            attrs.mtime = scp_sftp_mtime;
            sftp_register(req = fxp_fsetstat_send(scp_sftp_filehandle, attrs));
            rreq = sftp_find_request(pktin = sftp_recv());
            assert(rreq == req);
            ret = fxp_fsetstat_recv(pktin, rreq);
            if (!ret) {
                tell_user(stderr, "unable to set file times: %s\n", fxp_error());
                errs++;
            }
        }
        sftp_register(req = fxp_close_send(scp_sftp_filehandle));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        fxp_close_recv(pktin, rreq);
        scp_has_times = 0;
        return 0;
    } else {
        back->send(backhandle, "", 1);
        return response();
    }
}

char *scp_save_remotepath(void)
{
    if (using_sftp)
        return scp_sftp_remotepath;
    else
        return NULL;
}

void scp_restore_remotepath(char *data)
{
    if (using_sftp)
        scp_sftp_remotepath = data;
}

int scp_send_dirname(char *name, int modes)
{
    if (using_sftp) {
        char *fullname;
        char const *err;
        struct fxp_attrs attrs;
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;
        int ret;

        if (scp_sftp_targetisdir) {
            fullname = dupcat(scp_sftp_remotepath, "/", name, NULL);
        } else {
            fullname = dupstr(scp_sftp_remotepath);
        }

        /*
         * We don't worry about whether we managed to create the
         * directory, because if it exists already it's OK just to
         * use it. Instead, we will stat it afterwards, and if it
         * exists and is a directory we will assume we were either
         * successful or it didn't matter.
         */
        sftp_register(req = fxp_mkdir_send(fullname));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        ret = fxp_mkdir_recv(pktin, rreq);

        if (!ret)
            err = fxp_error();
        else
            err = "server reported no error";

        sftp_register(req = fxp_stat_send(fullname));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        ret = fxp_stat_recv(pktin, rreq, &attrs);

        if (!ret || !(attrs.flags & SSH_FILEXFER_ATTR_PERMISSIONS) ||
            !(attrs.permissions & 0040000)) {
            tell_user(stderr, "unable to create directory %s: %s",
                      fullname, err);
            errs++;
            return 1;
        }

        scp_sftp_remotepath = fullname;

        return 0;
    } else {
        char buf[40];
        sprintf(buf, "D%04o 0 ", modes);
        back->send(backhandle, buf, strlen(buf));
        back->send(backhandle, name, strlen(name));
        back->send(backhandle, "\n", 1);
        return response();
    }
}

int scp_send_enddir(void)
{
    if (using_sftp) {
        sfree(scp_sftp_remotepath);
        return 0;
    } else {
        back->send(backhandle, "E\n", 2);
        return response();
    }
}

/*
 * Yes, I know; I have an scp_sink_setup _and_ an scp_sink_init.
 * That's bad. The difference is that scp_sink_setup is called once
 * right at the start, whereas scp_sink_init is called to
 * initialise every level of recursion in the protocol.
 */
int scp_sink_setup(char *source, int preserve, int recursive)
{
    if (using_sftp) {
        char *newsource;

        if (!fxp_init()) {
            tell_user(stderr, "unable to initialise SFTP: %s", fxp_error());
            errs++;
            return 1;
        }
        /*
         * It's possible that the source string we've been given
         * contains a wildcard. If so, we must split the directory
         * away from the wildcard itself (throwing an error if any
         * wildcardness comes before the final slash) and arrange
         * things so that a dirstack entry will be set up.
         */
        newsource = snewn(1+strlen(source), char);
        if (!wc_unescape(newsource, source)) {
            /* Yes, here we go; it's a wildcard. Bah. */
            char *dupsource, *lastpart, *dirpart, *wildcard;
            dupsource = dupstr(source);
            lastpart = stripslashes(dupsource, 0);
            wildcard = dupstr(lastpart);
            *lastpart = '\0';
            if (*dupsource && dupsource[1]) {
                /*
                 * The remains of dupsource are at least two
                 * characters long, meaning the pathname wasn't
                 * empty or just `/'. Hence, we remove the trailing
                 * slash.
                 */
                lastpart[-1] = '\0';
            } else if (!*dupsource) {
                /*
                 * The remains of dupsource are _empty_ - the whole
                 * pathname was a wildcard. Hence we need to
                 * replace it with ".".
                 */
                sfree(dupsource);
                dupsource = dupstr(".");
            }

            /*
             * Now we have separated our string into dupsource (the
             * directory part) and wildcard. Both of these will
             * need freeing at some point. Next step is to remove
             * wildcard escapes from the directory part, throwing
             * an error if it contains a real wildcard.
             */
            dirpart = snewn(1+strlen(dupsource), char);
            if (!wc_unescape(dirpart, dupsource)) {
                tell_user(stderr, "%s: multiple-level wildcards unsupported",
                          source);
                errs++;
                sfree(dirpart);
                sfree(wildcard);
                sfree(dupsource);
                return 1;
            }

            /*
             * Now we have dirpart (unescaped, ie a valid remote
             * path), and wildcard (a wildcard). This will be
             * sufficient to arrange a dirstack entry.
             */
            scp_sftp_remotepath = dirpart;
            scp_sftp_wildcard = wildcard;
            sfree(dupsource);
        } else {
            scp_sftp_remotepath = newsource;
            scp_sftp_wildcard = NULL;
        }
        scp_sftp_preserve = preserve;
        scp_sftp_recursive = recursive;
        scp_sftp_donethistarget = 0;
        scp_sftp_dirstack_head = NULL;
    }
    return 0;
}

int scp_sink_init(void)
{
    if (!using_sftp) {
        back->send(backhandle, "", 1);
    }
    return 0;
}

#define SCP_SINK_FILE   1
#define SCP_SINK_DIR    2
#define SCP_SINK_ENDDIR 3
#define SCP_SINK_RETRY  4              /* not an action; just try again */
struct scp_sink_action {
    int action;                        /* FILE, DIR, ENDDIR */
    char *buf;                         /* will need freeing after use */
    char *name;                        /* filename or dirname (not ENDDIR) */
    int mode;                          /* access mode (not ENDDIR) */
    unsigned long size;                /* file size (not ENDDIR) */
    int settime;                       /* 1 if atime and mtime are filled */
    unsigned long atime, mtime;        /* access times for the file */
};

int scp_get_sink_action(struct scp_sink_action *act)
{
    if (using_sftp) {
        char *fname;
        int must_free_fname;
        struct fxp_attrs attrs;
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;
        int ret;

        if (!scp_sftp_dirstack_head) {
            if (!scp_sftp_donethistarget) {
                /*
                 * Simple case: we are only dealing with one file.
                 */
                fname = scp_sftp_remotepath;
                must_free_fname = 0;
                scp_sftp_donethistarget = 1;
            } else {
                /*
                 * Even simpler case: one file _which we've done_.
                 * Return 1 (finished).
                 */
                return 1;
            }
        } else {
            /*
             * We're now in the middle of stepping through a list
             * of names returned from fxp_readdir(); so let's carry
             * on.
             */
            struct scp_sftp_dirstack *head = scp_sftp_dirstack_head;
            while (head->namepos < head->namelen &&
                   (is_dots(head->names[head->namepos].filename) ||
                    (head->wildcard &&
                     !wc_match(head->wildcard,
                               head->names[head->namepos].filename))))
                head->namepos++;       /* skip . and .. */
            if (head->namepos < head->namelen) {
                head->matched_something = 1;
                fname = dupcat(head->dirpath, "/",
                               head->names[head->namepos++].filename,
                               NULL);
                must_free_fname = 1;
            } else {
                /*
                 * We've come to the end of the list; pop it off
                 * the stack and return an ENDDIR action (or RETRY
                 * if this was a wildcard match).
                 */
                if (head->wildcard) {
                    act->action = SCP_SINK_RETRY;
                    if (!head->matched_something) {
                        tell_user(stderr, "pscp: wildcard '%s' matched "
                                  "no files", head->wildcard);
                        errs++;
                    }
                    sfree(head->wildcard);

                } else {
                    act->action = SCP_SINK_ENDDIR;
                }

                sfree(head->dirpath);
                sfree(head->names);
                scp_sftp_dirstack_head = head->next;
                sfree(head);

                return 0;
            }
        }

        /*
         * Now we have a filename. Stat it, and see if it's a file
         * or a directory.
         */
        sftp_register(req = fxp_stat_send(fname));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        ret = fxp_stat_recv(pktin, rreq, &attrs);

        if (!ret || !(attrs.flags & SSH_FILEXFER_ATTR_PERMISSIONS)) {
            tell_user(stderr, "unable to identify %s: %s", fname,
                      ret ? "file type not supplied" : fxp_error());
            errs++;
            return 1;
        }

        if (attrs.permissions & 0040000) {
            struct scp_sftp_dirstack *newitem;
            struct fxp_handle *dirhandle;
            int nnames, namesize;
            struct fxp_name *ournames;
            struct fxp_names *names;

            /*
             * It's a directory. If we're not in recursive mode,
             * this merits a complaint (which is fatal if the name
             * was specified directly, but not if it was matched by
             * a wildcard).
             * 
             * We skip this complaint completely if
             * scp_sftp_wildcard is set, because that's an
             * indication that we're not actually supposed to
             * _recursively_ transfer the dir, just scan it for
             * things matching the wildcard.
             */
            if (!scp_sftp_recursive && !scp_sftp_wildcard) {
                tell_user(stderr, "pscp: %s: is a directory", fname);
                errs++;
                if (must_free_fname) sfree(fname);
                if (scp_sftp_dirstack_head) {
                    act->action = SCP_SINK_RETRY;
                    return 0;
                } else {
                    return 1;
                }
            }

            /*
             * Otherwise, the fun begins. We must fxp_opendir() the
             * directory, slurp the filenames into memory, return
             * SCP_SINK_DIR (unless this is a wildcard match), and
             * set targetisdir. The next time we're called, we will
             * run through the list of filenames one by one,
             * matching them against a wildcard if present.
             * 
             * If targetisdir is _already_ set (meaning we're
             * already in the middle of going through another such
             * list), we must push the other (target,namelist) pair
             * on a stack.
             */
            sftp_register(req = fxp_opendir_send(fname));
            rreq = sftp_find_request(pktin = sftp_recv());
            assert(rreq == req);
            dirhandle = fxp_opendir_recv(pktin, rreq);

            if (!dirhandle) {
                tell_user(stderr, "scp: unable to open directory %s: %s",
                          fname, fxp_error());
                if (must_free_fname) sfree(fname);
                errs++;
                return 1;
            }
            nnames = namesize = 0;
            ournames = NULL;
            while (1) {
                int i;

                sftp_register(req = fxp_readdir_send(dirhandle));
                rreq = sftp_find_request(pktin = sftp_recv());
                assert(rreq == req);
                names = fxp_readdir_recv(pktin, rreq);

                if (names == NULL) {
                    if (fxp_error_type() == SSH_FX_EOF)
                        break;
                    tell_user(stderr, "scp: reading directory %s: %s\n",
                              fname, fxp_error());
                    if (must_free_fname) sfree(fname);
                    sfree(ournames);
                    errs++;
                    return 1;
                }
                if (names->nnames == 0) {
                    fxp_free_names(names);
                    break;
                }
                if (nnames + names->nnames >= namesize) {
                    namesize += names->nnames + 128;
                    ournames = sresize(ournames, namesize, struct fxp_name);
                }
                for (i = 0; i < names->nnames; i++) {
                    if (!strcmp(names->names[i].filename, ".") ||
                        !strcmp(names->names[i].filename, "..")) {
                        /*
                         * . and .. are normal consequences of
                         * reading a directory, and aren't worth
                         * complaining about.
                         */
                    } else if (!vet_filename(names->names[i].filename)) {
                        tell_user(stderr, "ignoring potentially dangerous server-"
                                  "supplied filename '%s'\n",
                                  names->names[i].filename);
                    } else
                        ournames[nnames++] = names->names[i];
                }
                names->nnames = 0;             /* prevent free_names */
                fxp_free_names(names);
            }
            sftp_register(req = fxp_close_send(dirhandle));
            rreq = sftp_find_request(pktin = sftp_recv());
            assert(rreq == req);
            fxp_close_recv(pktin, rreq);

            newitem = snew(struct scp_sftp_dirstack);
            newitem->next = scp_sftp_dirstack_head;
            newitem->names = ournames;
            newitem->namepos = 0;
            newitem->namelen = nnames;
            if (must_free_fname)
                newitem->dirpath = fname;
            else
                newitem->dirpath = dupstr(fname);
            if (scp_sftp_wildcard) {
                newitem->wildcard = scp_sftp_wildcard;
                newitem->matched_something = 0;
                scp_sftp_wildcard = NULL;
            } else {
                newitem->wildcard = NULL;
            }
            scp_sftp_dirstack_head = newitem;

            if (newitem->wildcard) {
                act->action = SCP_SINK_RETRY;
            } else {
                act->action = SCP_SINK_DIR;
                act->buf = dupstr(stripslashes(fname, 0));
                act->name = act->buf;
                act->size = 0;         /* duhh, it's a directory */
                act->mode = 07777 & attrs.permissions;
                if (scp_sftp_preserve &&
                    (attrs.flags & SSH_FILEXFER_ATTR_ACMODTIME)) {
                    act->atime = attrs.atime;
                    act->mtime = attrs.mtime;
                    act->settime = 1;
                } else
                    act->settime = 0;
            }
            return 0;

        } else {
            /*
             * It's a file. Return SCP_SINK_FILE.
             */
            act->action = SCP_SINK_FILE;
            act->buf = dupstr(stripslashes(fname, 0));
            act->name = act->buf;
            if (attrs.flags & SSH_FILEXFER_ATTR_SIZE) {
                if (uint64_compare(attrs.size,
                                   uint64_make(0, ULONG_MAX)) > 0) {
                    act->size = ULONG_MAX;   /* *boggle* */
                } else
                    act->size = attrs.size.lo;
            } else
                act->size = ULONG_MAX;   /* no idea */
            act->mode = 07777 & attrs.permissions;
            if (scp_sftp_preserve &&
                (attrs.flags & SSH_FILEXFER_ATTR_ACMODTIME)) {
                act->atime = attrs.atime;
                act->mtime = attrs.mtime;
                act->settime = 1;
            } else
                act->settime = 0;
            if (must_free_fname)
                scp_sftp_currentname = fname;
            else
                scp_sftp_currentname = dupstr(fname);
            return 0;
        }

    } else {
        int done = 0;
        int i, bufsize;
        int action;
        char ch;

        act->settime = 0;
        act->buf = NULL;
        bufsize = 0;

        while (!done) {
            if (ssh_scp_recv((unsigned char *) &ch, 1) <= 0)
                return 1;
            if (ch == '\n')
                bump("Protocol error: Unexpected newline");
            i = 0;
            action = ch;
            do {
                if (ssh_scp_recv((unsigned char *) &ch, 1) <= 0)
                    bump("Lost connection");
                if (i >= bufsize) {
                    bufsize = i + 128;
                    act->buf = sresize(act->buf, bufsize, char);
                }
                act->buf[i++] = ch;
            } while (ch != '\n');
            act->buf[i - 1] = '\0';
            switch (action) {
              case '\01':                      /* error */
                tell_user(stderr, "%s\n", act->buf);
                errs++;
                continue;                      /* go round again */
              case '\02':                      /* fatal error */
                bump("%s", act->buf);
              case 'E':
                back->send(backhandle, "", 1);
                act->action = SCP_SINK_ENDDIR;
                return 0;
              case 'T':
                if (sscanf(act->buf, "%ld %*d %ld %*d",
                           &act->mtime, &act->atime) == 2) {
                    act->settime = 1;
                    back->send(backhandle, "", 1);
                    continue;          /* go round again */
                }
                bump("Protocol error: Illegal time format");
              case 'C':
              case 'D':
                act->action = (action == 'C' ? SCP_SINK_FILE : SCP_SINK_DIR);
                break;
              default:
                bump("Protocol error: Expected control record");
            }
            /*
             * We will go round this loop only once, unless we hit
             * `continue' above.
             */
            done = 1;
        }

        /*
         * If we get here, we must have seen SCP_SINK_FILE or
         * SCP_SINK_DIR.
         */
        if (sscanf(act->buf, "%o %lu %n", &act->mode, &act->size, &i) != 2)
            bump("Protocol error: Illegal file descriptor format");
        act->name = act->buf + i;
        return 0;
    }
}

int scp_accept_filexfer(void)
{
    if (using_sftp) {
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;

        sftp_register(req = fxp_open_send(scp_sftp_currentname, SSH_FXF_READ));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        scp_sftp_filehandle = fxp_open_recv(pktin, rreq);

        if (!scp_sftp_filehandle) {
            tell_user(stderr, "pscp: unable to open %s: %s",
                      scp_sftp_currentname, fxp_error());
            errs++;
            return 1;
        }
        scp_sftp_fileoffset = uint64_make(0, 0);
        scp_sftp_xfer = xfer_download_init(scp_sftp_filehandle,
                                           scp_sftp_fileoffset);
        sfree(scp_sftp_currentname);
        return 0;
    } else {
        back->send(backhandle, "", 1);
        return 0;                      /* can't fail */
    }
}

int scp_recv_filedata(char *data, int len)
{
    if (using_sftp) {
        struct sftp_packet *pktin;
        int ret, actuallen;
        void *vbuf;

        xfer_download_queue(scp_sftp_xfer);
        pktin = sftp_recv();
        ret = xfer_download_gotpkt(scp_sftp_xfer, pktin);

        if (ret < 0) {
            tell_user(stderr, "pscp: error while reading: %s", fxp_error());
            errs++;
            return -1;
        }

        if (xfer_download_data(scp_sftp_xfer, &vbuf, &actuallen)) {
            /*
             * This assertion relies on the fact that the natural
             * block size used in the xfer manager is at most that
             * used in this module. I don't like crossing layers in
             * this way, but it'll do for now.
             */
            assert(actuallen <= len);
            memcpy(data, vbuf, actuallen);
            sfree(vbuf);
        } else
            actuallen = 0;

        scp_sftp_fileoffset = uint64_add32(scp_sftp_fileoffset, actuallen);

        return actuallen;
    } else {
        return ssh_scp_recv((unsigned char *) data, len);
    }
}

int scp_finish_filerecv(void)
{
    if (using_sftp) {
        struct sftp_packet *pktin;
        struct sftp_request *req, *rreq;

        /*
         * Ensure that xfer_done() will work correctly, so we can
         * clean up any outstanding requests from the file
         * transfer.
         */
        xfer_set_error(scp_sftp_xfer);
        while (!xfer_done(scp_sftp_xfer)) {
            void *vbuf;
            int len;

            pktin = sftp_recv();
            xfer_download_gotpkt(scp_sftp_xfer, pktin);
            if (xfer_download_data(scp_sftp_xfer, &vbuf, &len))
                sfree(vbuf);
        }
        xfer_cleanup(scp_sftp_xfer);

        sftp_register(req = fxp_close_send(scp_sftp_filehandle));
        rreq = sftp_find_request(pktin = sftp_recv());
        assert(rreq == req);
        fxp_close_recv(pktin, rreq);
        return 0;
    } else {
        back->send(backhandle, "", 1);
        return response();
    }
}

/* ----------------------------------------------------------------------
 *  Send an error message to the other side and to the screen.
 *  Increment error counter.
 */
static void run_err(const char *fmt, ...)
{
    char *str, *str2;
    va_list ap;
    va_start(ap, fmt);
    errs++;
    str = dupvprintf(fmt, ap);
    str2 = dupcat("scp: ", str, "\n", NULL);
    sfree(str);
    scp_send_errmsg(str2);
    tell_user(stderr, "%s", str2);
    va_end(ap);
    sfree(str2);
}

/*
 *  Execute the source part of the SCP protocol.
 */
static void source(char *src)
{
    unsigned long size;
    unsigned long mtime, atime;
    char *last;
    RFile *f;
    int attr;
    unsigned long i;
    unsigned long stat_bytes;
    time_t stat_starttime, stat_lasttime;

    attr = file_type(src);
    if (attr == FILE_TYPE_NONEXISTENT ||
        attr == FILE_TYPE_WEIRD) {
        run_err("%s: %s file or directory", src,
                (attr == FILE_TYPE_WEIRD ? "Not a" : "No such"));
        return;
    }

    if (attr == FILE_TYPE_DIRECTORY) {
        if (recursive) {
            /*
             * Avoid . and .. directories.
             */
            char *p;
            p = strrchr(src, '/');
            if (!p)
                p = strrchr(src, '\\');
            if (!p)
                p = src;
            else
                p++;
            if (!strcmp(p, ".") || !strcmp(p, ".."))
                /* skip . and .. */ ;
            else
                rsource(src);
        } else {
            run_err("%s: not a regular file", src);
        }
        return;
    }

    if ((last = strrchr(src, '/')) == NULL)
        last = src;
    else
        last++;
    if (strrchr(last, '\\') != NULL)
        last = strrchr(last, '\\') + 1;
    if (last == src && strchr(src, ':') != NULL)
        last = strchr(src, ':') + 1;

    f = open_existing_file(src, &size, &mtime, &atime);
    if (f == NULL) {
        run_err("%s: Cannot open file", src);
        return;
    }
    if (preserve) {
        if (scp_send_filetimes(mtime, atime))
            return;
    }

    if (verbose)
        tell_user(stderr, "Sending file %s, size=%lu", last, size);
    if (scp_send_filename(last, size, 0644))
        return;

    stat_bytes = 0;
    stat_starttime = time(NULL);
    stat_lasttime = 0;

    for (i = 0; i < size; i += 4096) {
        char transbuf[4096];
        int j, k = 4096;

        if (i + k > size)
            k = size - i;
        if ((j = read_from_file(f, transbuf, k)) != k) {
            if (statistics)
                printf("\n");
            bump("%s: Read error", src);
        }
        if (scp_send_filedata(transbuf, k))
            bump("%s: Network error occurred", src);

        if (statistics) {
            stat_bytes += k;
            if (time(NULL) != stat_lasttime || i + k == size) {
                stat_lasttime = time(NULL);
                print_stats(last, size, stat_bytes,
                            stat_starttime, stat_lasttime);
            }
        }

    }
    close_rfile(f);

    (void) scp_send_finish();
}

/*
 *  Recursively send the contents of a directory.
 */
static void rsource(char *src)
{
    char *last;
    char *save_target;
    DirHandle *dir;

    if ((last = strrchr(src, '/')) == NULL)
        last = src;
    else
        last++;
    if (strrchr(last, '\\') != NULL)
        last = strrchr(last, '\\') + 1;
    if (last == src && strchr(src, ':') != NULL)
        last = strchr(src, ':') + 1;

    /* maybe send filetime */

    save_target = scp_save_remotepath();

    if (verbose)
        tell_user(stderr, "Entering directory: %s", last);
    if (scp_send_dirname(last, 0755))
        return;

    dir = open_directory(src);
    if (dir != NULL) {
        char *filename;
        while ((filename = read_filename(dir)) != NULL) {
            char *foundfile = dupcat(src, "/", filename, NULL);
            source(foundfile);
            sfree(foundfile);
            sfree(filename);
        }
    }
    close_directory(dir);

    (void) scp_send_enddir();

    scp_restore_remotepath(save_target);
}

/*
 * Execute the sink part of the SCP protocol.
 */
static void sink(char *targ, char *src)
{
    char *destfname;
    int targisdir = 0;
    int exists;
    int attr;
    WFile *f;
    unsigned long received;
    int wrerror = 0;
    unsigned long stat_bytes;
    time_t stat_starttime, stat_lasttime;
    char *stat_name;

    attr = file_type(targ);
    if (attr == FILE_TYPE_DIRECTORY)
        targisdir = 1;

    if (targetshouldbedirectory && !targisdir)
        bump("%s: Not a directory", targ);

    scp_sink_init();
    while (1) {
        struct scp_sink_action act;
        if (scp_get_sink_action(&act))
            return;

        if (act.action == SCP_SINK_ENDDIR)
            return;

        if (act.action == SCP_SINK_RETRY)
            continue;

        if (targisdir) {
            /*
             * Prevent the remote side from maliciously writing to
             * files outside the target area by sending a filename
             * containing `../'. In fact, it shouldn't be sending
             * filenames with any slashes or colons in at all; so
             * we'll find the last slash, backslash or colon in the
             * filename and use only the part after that. (And
             * warn!)
             * 
             * In addition, we also ensure here that if we're
             * copying a single file and the target is a directory
             * (common usage: `pscp host:filename .') the remote
             * can't send us a _different_ file name. We can
             * distinguish this case because `src' will be non-NULL
             * and the last component of that will fail to match
             * (the last component of) the name sent.
             * 
             * Well, not always; if `src' is a wildcard, we do
             * expect to get back filenames that don't correspond
             * exactly to it. Ideally in this case, we would like
             * to ensure that the returned filename actually
             * matches the wildcard pattern - but one of SCP's
             * protocol infelicities is that wildcard matching is
             * done at the server end _by the server's rules_ and
             * so in general this is infeasible. Hence, we only
             * accept filenames that don't correspond to `src' if
             * unsafe mode is enabled or we are using SFTP (which
             * resolves remote wildcards on the client side and can
             * be trusted).
             */
            char *striptarget, *stripsrc;

            striptarget = stripslashes(act.name, 1);
            if (striptarget != act.name) {
                tell_user(stderr, "warning: remote host sent a compound"
                          " pathname '%s'", act.name);
                tell_user(stderr, "         renaming local file to '%s'",
                          striptarget);
            }

            /*
             * Also check to see if the target filename is '.' or
             * '..', or indeed '...' and so on because Windows
             * appears to interpret those like '..'.
             */
            if (is_dots(striptarget)) {
                bump("security violation: remote host attempted to write to"
                     " a '.' or '..' path!");
            }

            if (src) {
                stripsrc = stripslashes(src, 1);
                if (strcmp(striptarget, stripsrc) &&
                    !using_sftp && !scp_unsafe_mode) {
                    tell_user(stderr, "warning: remote host tried to write "
                              "to a file called '%s'", striptarget);
                    tell_user(stderr, "         when we requested a file "
                              "called '%s'.", stripsrc);
                    tell_user(stderr, "         If this is a wildcard, "
                              "consider upgrading to SSH-2 or using");
                    tell_user(stderr, "         the '-unsafe' option. Renaming"
                              " of this file has been disallowed.");
                    /* Override the name the server provided with our own. */
                    striptarget = stripsrc;
                }
            }

            if (targ[0] != '\0')
                destfname = dir_file_cat(targ, striptarget);
            else
                destfname = dupstr(striptarget);
        } else {
            /*
             * In this branch of the if, the target area is a
             * single file with an explicitly specified name in any
             * case, so there's no danger.
             */
            destfname = dupstr(targ);
        }
        attr = file_type(destfname);
        exists = (attr != FILE_TYPE_NONEXISTENT);

        if (act.action == SCP_SINK_DIR) {
            if (exists && attr != FILE_TYPE_DIRECTORY) {
                run_err("%s: Not a directory", destfname);
                continue;
            }
            if (!exists) {
                if (!create_directory(destfname)) {
                    run_err("%s: Cannot create directory", destfname);
                    continue;
                }
            }
            sink(destfname, NULL);
            /* can we set the timestamp for directories ? */
            continue;
        }

        f = open_new_file(destfname);
        if (f == NULL) {
            run_err("%s: Cannot create file", destfname);
            continue;
        }

        if (scp_accept_filexfer())
            return;

        stat_bytes = 0;
        stat_starttime = time(NULL);
        stat_lasttime = 0;
        stat_name = stripslashes(destfname, 1);

        received = 0;
        while (received < act.size) {
            char transbuf[4096];
            unsigned long blksize;
            int read;
            blksize = 4096;
            if (blksize > (act.size - received))
                blksize = act.size - received;
            read = scp_recv_filedata(transbuf, (int)blksize);
            if (read <= 0)
                bump("Lost connection");
            if (wrerror)
                continue;
            if (write_to_file(f, transbuf, read) != (int)read) {
                wrerror = 1;
                /* FIXME: in sftp we can actually abort the transfer */
                if (statistics)
                    printf("\r%-25.25s | %50s\n",
                           stat_name,
                           "Write error.. waiting for end of file");
                continue;
            }
            if (statistics) {
                stat_bytes += read;
                if (time(NULL) > stat_lasttime ||
                    received + read == act.size) {
                    stat_lasttime = time(NULL);
                    print_stats(stat_name, act.size, stat_bytes,
                                stat_starttime, stat_lasttime);
                }
            }
            received += read;
        }
        if (act.settime) {
            set_file_times(f, act.mtime, act.atime);
        }

        close_wfile(f);
        if (wrerror) {
            run_err("%s: Write error", destfname);
            continue;
        }
        (void) scp_finish_filerecv();
        sfree(destfname);
        sfree(act.buf);
    }
}

/*
 * We will copy local files to a remote server.
 */
static void toremote(int argc, char *argv[])
{
    char *src, *targ, *host, *user;
    char *cmd;
    int i, wc_type;

    targ = argv[argc - 1];

    /* Separate host from filename */
    host = targ;
    targ = colon(targ);
    if (targ == NULL)
        bump("targ == NULL in toremote()");
    *targ++ = '\0';
    if (*targ == '\0')
        targ = ".";
    /* Substitute "." for empty target */

    /* Separate host and username */
    user = host;
    host = strrchr(host, '@');
    if (host == NULL) {
        host = user;
        user = NULL;
    } else {
        *host++ = '\0';
        if (*user == '\0')
            user = NULL;
    }

    if (argc == 2) {
        if (colon(argv[0]) != NULL)
            bump("%s: Remote to remote not supported", argv[0]);

        wc_type = test_wildcard(argv[0], 1);
        if (wc_type == WCTYPE_NONEXISTENT)
            bump("%s: No such file or directory\n", argv[0]);
        else if (wc_type == WCTYPE_WILDCARD)
            targetshouldbedirectory = 1;
    }

    cmd = dupprintf("scp%s%s%s%s -t %s",
                    verbose ? " -v" : "",
                    recursive ? " -r" : "",
                    preserve ? " -p" : "",
                    targetshouldbedirectory ? " -d" : "", targ);
    do_cmd(host, user, cmd);
    sfree(cmd);

    scp_source_setup(targ, targetshouldbedirectory);

    for (i = 0; i < argc - 1; i++) {
        src = argv[i];
        if (colon(src) != NULL) {
            tell_user(stderr, "%s: Remote to remote not supported\n", src);
            errs++;
            continue;
        }

        wc_type = test_wildcard(src, 1);
        if (wc_type == WCTYPE_NONEXISTENT) {
            run_err("%s: No such file or directory", src);
            continue;
        } else if (wc_type == WCTYPE_FILENAME) {
            source(src);
            continue;
        } else {
            WildcardMatcher *wc;
            char *filename;

            wc = begin_wildcard_matching(src);
            if (wc == NULL) {
                run_err("%s: No such file or directory", src);
                continue;
            }

            while ((filename = wildcard_get_filename(wc)) != NULL) {
                source(filename);
                sfree(filename);
            }

            finish_wildcard_matching(wc);
        }
    }
}

/*
 *  We will copy files from a remote server to the local machine.
 */
static void tolocal(int argc, char *argv[])
{
    char *src, *targ, *host, *user;
    char *cmd;

    if (argc != 2)
        bump("More than one remote source not supported");

    src = argv[0];
    targ = argv[1];

    /* Separate host from filename */
    host = src;
    src = colon(src);
    if (src == NULL)
        bump("Local to local copy not supported");
    *src++ = '\0';
    if (*src == '\0')
        src = ".";
    /* Substitute "." for empty filename */

    /* Separate username and hostname */
    user = host;
    host = strrchr(host, '@');
    if (host == NULL) {
        host = user;
        user = NULL;
    } else {
        *host++ = '\0';
        if (*user == '\0')
            user = NULL;
    }

    cmd = dupprintf("scp%s%s%s%s -f %s",
                    verbose ? " -v" : "",
                    recursive ? " -r" : "",
                    preserve ? " -p" : "",
                    targetshouldbedirectory ? " -d" : "", src);
    do_cmd(host, user, cmd);
    sfree(cmd);

    if (scp_sink_setup(src, preserve, recursive))
        return;

    sink(targ, src);
}

/*
 *  We will issue a list command to get a remote directory.
 */
static void get_dir_list(int argc, char *argv[])
{
    char *src, *host, *user;
    char *cmd, *p, *q;
    char c;

    src = argv[0];

    /* Separate host from filename */
    host = src;
    src = colon(src);
    if (src == NULL)
        bump("Local to local copy not supported");
    *src++ = '\0';
    if (*src == '\0')
        src = ".";
    /* Substitute "." for empty filename */

    /* Separate username and hostname */
    user = host;
    host = strrchr(host, '@');
    if (host == NULL) {
        host = user;
        user = NULL;
    } else {
        *host++ = '\0';
        if (*user == '\0')
            user = NULL;
    }

    cmd = snewn(4 * strlen(src) + 100, char);
    strcpy(cmd, "ls -la '");
    p = cmd + strlen(cmd);
    for (q = src; *q; q++) {
        if (*q == '\'') {
            *p++ = '\'';
            *p++ = '\\';
            *p++ = '\'';
            *p++ = '\'';
        } else {
            *p++ = *q;
        }
    }
    *p++ = '\'';
    *p = '\0';

    do_cmd(host, user, cmd);
    sfree(cmd);

    if (using_sftp) {
        scp_sftp_listdir(src);
    } else {
        while (ssh_scp_recv((unsigned char *) &c, 1) > 0)
            tell_char(stdout, c);
    }
}

/*
 *  Short description of parameters.
 */
static void usage(void)
{
    printf("PuTTY Secure Copy client\n");
    printf("%s\n", ver);
    printf("Usage: pscp [options] [user@]host:source target\n");
    printf
        ("       pscp [options] source [source...] [user@]host:target\n");
    printf("       pscp [options] -ls [user@]host:filespec\n");
    printf("Options:\n");
    printf("  -V        print version information and exit\n");
    printf("  -pgpfp    print PGP key fingerprints and exit\n");
    printf("  -p        preserve file attributes\n");
    printf("  -q        quiet, don't show statistics\n");
    printf("  -r        copy directories recursively\n");
    printf("  -v        show verbose messages\n");
    printf("  -load sessname  Load settings from saved session\n");
    printf("  -P port   connect to specified port\n");
    printf("  -l user   connect with specified username\n");
    printf("  -pw passw login with specified password\n");
    printf("  -1 -2     force use of particular SSH protocol version\n");
    printf("  -4 -6     force use of IPv4 or IPv6\n");
    printf("  -C        enable compression\n");
    printf("  -i key    private key file for authentication\n");
    printf("  -batch    disable all interactive prompts\n");
    printf("  -unsafe   allow server-side wildcards (DANGEROUS)\n");
    printf("  -sftp     force use of SFTP protocol\n");
    printf("  -scp      force use of SCP protocol\n");
#if 0
    /*
     * -gui is an internal option, used by GUI front ends to get
     * pscp to pass progress reports back to them. It's not an
     * ordinary user-accessible option, so it shouldn't be part of
     * the command-line help. The only people who need to know
     * about it are programmers, and they can read the source.
     */
    printf
        ("  -gui hWnd GUI mode with the windows handle for receiving messages\n");
#endif
    cleanup_exit(1);
}

void version(void)
{
    printf("pscp: %s\n", ver);
    cleanup_exit(1);
}

void cmdline_error(char *p, ...)
{
    va_list ap;
    fprintf(stderr, "pscp: ");
    va_start(ap, p);
    vfprintf(stderr, p, ap);
    va_end(ap);
    fprintf(stderr, "\n      try typing just \"pscp\" for help\n");
    exit(1);
}

/*
 * Main program. (Called `psftp_main' because it gets called from
 * *sftp.c; bit silly, I know, but it had to be called _something_.)
 */
int psftp_main(int argc, char *argv[])
{
    int i;

    default_protocol = PROT_TELNET;

    flags = FLAG_STDERR
#ifdef FLAG_SYNCAGENT
        | FLAG_SYNCAGENT
#endif
        ;
    cmdline_tooltype = TOOLTYPE_FILETRANSFER;
    ssh_get_line = &console_get_line;
    sk_init();

    /* Load Default Settings before doing anything else. */
    do_defaults(NULL, &cfg);
    loaded_session = FALSE;

    for (i = 1; i < argc; i++) {
        int ret;
        if (argv[i][0] != '-')
            break;
        ret = cmdline_process_param(argv[i], i+1<argc?argv[i+1]:NULL, 1, &cfg);
        if (ret == -2) {
            cmdline_error("option \"%s\" requires an argument", argv[i]);
        } else if (ret == 2) {
            i++;               /* skip next argument */
        } else if (ret == 1) {
            /* We have our own verbosity in addition to `flags'. */
            if (flags & FLAG_VERBOSE)
                verbose = 1;
        } else if (strcmp(argv[i], "-pgpfp") == 0) {
            pgp_fingerprints();
            return 1;
        } else if (strcmp(argv[i], "-r") == 0) {
            recursive = 1;
        } else if (strcmp(argv[i], "-p") == 0) {
            preserve = 1;
        } else if (strcmp(argv[i], "-q") == 0) {
            statistics = 0;
        } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "-?") == 0) {
            usage();
        } else if (strcmp(argv[i], "-V") == 0) {
            version();
        } else if (strcmp(argv[i], "-gui") == 0 && i + 1 < argc) {
            gui_enable(argv[++i]);
            gui_mode = 1;
            console_batch_mode = TRUE;
        } else if (strcmp(argv[i], "-ls") == 0) {
            list = 1;
        } else if (strcmp(argv[i], "-batch") == 0) {
            console_batch_mode = 1;
        } else if (strcmp(argv[i], "-unsafe") == 0) {
            scp_unsafe_mode = 1;
        } else if (strcmp(argv[i], "-sftp") == 0) {
            try_scp = 0; try_sftp = 1;
        } else if (strcmp(argv[i], "-scp") == 0) {
            try_scp = 1; try_sftp = 0;
        } else if (strcmp(argv[i], "--") == 0) {
            i++;
            break;
        } else {
            cmdline_error("unknown option \"%s\"", argv[i]);
        }
    }
    argc -= i;
    argv += i;
    back = NULL;

    if (list) {
        if (argc != 1)
            usage();
        get_dir_list(argc, argv);

    } else {

        if (argc < 2)
            usage();
        if (argc > 2)
            targetshouldbedirectory = 1;

        if (colon(argv[argc - 1]) != NULL)
            toremote(argc, argv);
        else
            tolocal(argc, argv);
    }

    if (back != NULL && back->socket(backhandle) != NULL) {
        char ch;
        back->special(backhandle, TS_EOF);
        ssh_scp_recv((unsigned char *) &ch, 1);
    }
    random_save_seed();

    if (gui_mode)
        gui_send_errcount(list, errs);

    cmdline_cleanup();
    console_provide_logctx(NULL);
    back->free(backhandle);
    backhandle = NULL;
    back = NULL;
    sk_cleanup();
    return (errs == 0 ? 0 : 1);
}

/* end */