/*
 * Copyright (c) 1997-2004 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * 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 Institute 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 INSTITUTE 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 INSTITUTE 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 "push_locl.h"
RCSID("$Id$");

#if defined(_AIX) && defined(STAT)
/*
 * AIX defines STAT to 1 in sys/dir.h
 */
#  undef STAT
#endif

#ifdef KRB5
static int use_v5 = -1;
static krb5_context context;
#endif

static char *port_str;
static int verbose_level;
static int do_fork;
static int do_leave;
static int do_version;
static int do_help;
static int do_from;
static int do_count;
static char *header_str;

struct getargs args[] = {
#ifdef KRB5
    { "krb5",   '5', arg_flag,          &use_v5,        "Use Kerberos V5",
      NULL },
#endif
    { "verbose",'v', arg_counter,       &verbose_level, "Verbose",
      NULL },
    { "fork",   'f', arg_flag,          &do_fork,       "Fork deleting proc",
      NULL },
    { "leave",  'l', arg_flag,          &do_leave,      "Leave mail on server",
      NULL },
    { "port",   'p', arg_string,        &port_str,      "Use this port",
      "number-or-service" },
    { "from",    0,  arg_flag,          &do_from,       "Behave like from",
      NULL },
    { "headers", 0,  arg_string,        &header_str,    "Headers to print", NULL },
    { "count", 'c',  arg_flag,          &do_count,      "Print number of messages", NULL},
    { "version", 0,  arg_flag,          &do_version,    "Print version",
      NULL },
    { "help",    0,  arg_flag,          &do_help,       NULL,
      NULL }

};

static void
usage (int ret)
{
    arg_printusage (args,
                    sizeof(args) / sizeof(args[0]),
                    NULL,
                    "[[{po:username[@hostname] | hostname[:username]}] ...] "
                    "filename");
    exit (ret);
}

static int
do_connect (const char *hostname, int port, int nodelay)
{
    struct addrinfo *ai, *a;
    struct addrinfo hints;
    int error;
    int s = -1;
    char portstr[NI_MAXSERV];

    memset (&hints, 0, sizeof(hints));
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    snprintf (portstr, sizeof(portstr), "%u", ntohs(port));

    error = getaddrinfo (hostname, portstr, &hints, &ai);
    if (error)
        errx (1, "getaddrinfo(%s): %s", hostname, gai_strerror(error));

    for (a = ai; a != NULL; a = a->ai_next) {
        s = socket (a->ai_family, a->ai_socktype, a->ai_protocol);
        if (s < 0)
            continue;
        if (connect (s, a->ai_addr, a->ai_addrlen) < 0) {
            warn ("connect(%s)", hostname);
            close (s);
            continue;
        }
        break;
    }
    freeaddrinfo (ai);
    if (a == NULL) {
        warnx ("failed to contact %s", hostname);
        return -1;
    }

    if(setsockopt(s, IPPROTO_TCP, TCP_NODELAY,
                  (void *)&nodelay, sizeof(nodelay)) < 0)
        err (1, "setsockopt TCP_NODELAY");
    return s;
}

typedef enum { INIT = 0, GREET, USER, PASS, STAT, RETR, TOP,
               DELE, XDELE, QUIT} pop_state;

static char *pop_state_string[] = {
    "INIT", "GREET", "USER", "PASS", "STAT", "RETR", "TOP",
    "DELE", "XDELE", "QUIT"
};

#define PUSH_BUFSIZ 65536

#define STEP 16

struct write_state {
    struct iovec *iovecs;
    size_t niovecs, maxiovecs, allociovecs;
    int fd;
};

static void
write_state_init (struct write_state *w, int fd)
{
#ifdef UIO_MAXIOV
    w->maxiovecs = UIO_MAXIOV;
#else
    w->maxiovecs = 16;
#endif
    w->allociovecs = min(STEP, w->maxiovecs);
    w->niovecs = 0;
    w->iovecs = emalloc(w->allociovecs * sizeof(*w->iovecs));
    w->fd = fd;
}

static void
write_state_add (struct write_state *w, void *v, size_t len)
{
    if(w->niovecs == w->allociovecs) {
        if(w->niovecs == w->maxiovecs) {
            if(writev (w->fd, w->iovecs, w->niovecs) < 0)
                err(1, "writev");
            w->niovecs = 0;
        } else {
            w->allociovecs = min(w->allociovecs + STEP, w->maxiovecs);
            w->iovecs = erealloc (w->iovecs,
                                  w->allociovecs * sizeof(*w->iovecs));
        }
    }
    w->iovecs[w->niovecs].iov_base = v;
    w->iovecs[w->niovecs].iov_len  = len;
    ++w->niovecs;
}

static void
write_state_flush (struct write_state *w)
{
    if (w->niovecs) {
        if (writev (w->fd, w->iovecs, w->niovecs) < 0)
            err (1, "writev");
        w->niovecs = 0;
    }
}

static void
write_state_destroy (struct write_state *w)
{
    free (w->iovecs);
}

static int
doit(int s,
     const char *host,
     const char *user,
     const char *outfilename,
     const char *header_str,
     int leavep,
     int verbose,
     int forkp)
{
    int ret;
    char out_buf[PUSH_BUFSIZ];
    int out_len = 0;
    char *in_buf;
    size_t in_buf_size;
    size_t in_len = 0;
    char *in_ptr;
    pop_state state = INIT;
    unsigned count = 0, bytes;
    unsigned asked_for = 0, retrieved = 0, asked_deleted = 0, deleted = 0;
    unsigned sent_xdele = 0;
    int out_fd;
    char from_line[128];
    size_t from_line_length;
    time_t now;
    struct write_state write_state;
    unsigned int numheaders = 1;
    char **headers = NULL;
    int i;
    char *tmp = NULL;

    in_buf = emalloc(PUSH_BUFSIZ + 1);
    in_ptr = in_buf;
    in_buf_size = PUSH_BUFSIZ;

    if (do_from) {
        char *tmp2;

        tmp2 = tmp = estrdup(header_str);

        out_fd = -1;
        if (verbose)
            fprintf (stderr, "%s@%s\n", user, host);
        while (*tmp != '\0') {
            tmp = strchr(tmp, ',');
            if (tmp == NULL)
                break;
            tmp++;
            numheaders++;
        }

        headers = emalloc(sizeof(char *) * (numheaders + 1));
        for (i = 0; i < numheaders; i++) {
            headers[i] = strtok_r(tmp2, ",", &tmp2);
        }
        headers[numheaders] = NULL;
    } else {
        out_fd = open(outfilename, O_WRONLY | O_APPEND | O_CREAT, 0666);
        if (out_fd < 0)
            err (1, "open %s", outfilename);
        if (verbose)
            fprintf (stderr, "%s@%s -> %s\n", user, host, outfilename);
    }

    now = time(NULL);
    from_line_length = snprintf (from_line, sizeof(from_line),
                                 "From %s %s", "push", ctime(&now));
    if (from_line_length < 0 || from_line_length > sizeof(from_line))
        errx (1, "snprintf failed");

    out_len = snprintf (out_buf, sizeof(out_buf),
                        "USER %s\r\nPASS hej\r\nSTAT\r\n",
                        user);
    if (out_len < 0 || out_len > sizeof(out_buf))
        errx (1, "snprintf failed");
    if (net_write (s, out_buf, out_len) != out_len)
        err (1, "write");
    if (verbose > 1)
        fprintf (stderr, "%s", out_buf);

    if (!do_from)
        write_state_init (&write_state, out_fd);

    while(state != QUIT) {
        fd_set readset, writeset;

        FD_ZERO(&readset);
        FD_ZERO(&writeset);
        if (s >= FD_SETSIZE)
            errx (1, "fd too large");
        FD_SET(s,&readset);

        if (verbose > 1)
            fprintf (stderr, "state: %s count: %d asked_for: %d "
                     "retrieved: %d asked_deleted: %d\n",
                     pop_state_string[state],
                     count, asked_for, retrieved, asked_deleted);

        if (((state == STAT || state == RETR || state == TOP)
             && asked_for < count)
            || (state == XDELE && !sent_xdele)
            || (state == DELE && asked_deleted < count))
            FD_SET(s,&writeset);
        ret = select (s + 1, &readset, &writeset, NULL, NULL);
        if (ret < 0) {
            if (errno == EAGAIN)
                continue;
            else
                err (1, "select");
        }

        if (FD_ISSET(s, &readset)) {
            char *beg, *p;
            size_t rem;
            int blank_line = 0;

            if(in_len >= in_buf_size) {
                char *tmp = erealloc(in_buf, in_buf_size + PUSH_BUFSIZ + 1);
                in_ptr = tmp + (in_ptr - in_buf);
                in_buf = tmp;
                in_buf_size += PUSH_BUFSIZ;
            }

            ret = read (s, in_ptr, in_buf_size - in_len);
            if (ret < 0)
                err (1, "read");
            else if (ret == 0)
                errx (1, "EOF during read");

            in_len += ret;
            in_ptr += ret;
            *in_ptr = '\0';

            beg = in_buf;
            rem = in_len;
            while(rem > 1
                  && (p = strstr(beg, "\r\n")) != NULL) {
                if (state == TOP) {
                    char *copy = beg;

                    for (i = 0; i < numheaders; i++) {
                        size_t len;

                        len = min(p - copy + 1, strlen(headers[i]));
                        if (strncasecmp(copy, headers[i], len) == 0) {
                            fprintf (stdout, "%.*s\n", (int)(p - copy), copy);
                        }
                    }
                    if (beg[0] == '.' && beg[1] == '\r' && beg[2] == '\n') {
                        if (numheaders > 1)
                            fprintf (stdout, "\n");
                        state = STAT;
                        if (++retrieved == count) {
                            state = QUIT;
                            net_write (s, "QUIT\r\n", 6);
                            if (verbose > 1)
                                fprintf (stderr, "QUIT\r\n");
                        }
                    }
                    rem -= p - beg + 2;
                    beg = p + 2;
                } else if (state == RETR) {
                    char *copy = beg;
                    if (beg[0] == '.') {
                        if (beg[1] == '\r' && beg[2] == '\n') {
                            if(!blank_line)
                                write_state_add(&write_state, "\n", 1);
                            state = STAT;
                            rem -= p - beg + 2;
                            beg = p + 2;
                            if (++retrieved == count) {
                                write_state_flush (&write_state);
                                if (fsync (out_fd) < 0)
                                    err (1, "fsync");
                                close(out_fd);
                                if (leavep) {
                                    state = QUIT;
                                    net_write (s, "QUIT\r\n", 6);
                                    if (verbose > 1)
                                        fprintf (stderr, "QUIT\r\n");
                                } else {
                                    if (forkp) {
                                        pid_t pid;

                                        pid = fork();
                                        if (pid < 0)
                                            warn ("fork");
                                        else if(pid != 0) {
                                            if(verbose)
                                                fprintf (stderr,
                                                         "(exiting)");
                                            return 0;
                                        }
                                    }

                                    state = XDELE;
                                    if (verbose)
                                        fprintf (stderr, "deleting... ");
                                }
                            }
                            continue;
                        } else
                            ++copy;
                    }
                    *p = '\n';
                    if(blank_line &&
                       strncmp(copy, "From ", min(p - copy + 1, 5)) == 0)
                        write_state_add(&write_state, ">", 1);
                    write_state_add(&write_state, copy, p - copy + 1);
                    blank_line = (*copy == '\n');
                    rem -= p - beg + 2;
                    beg = p + 2;
                } else if (rem >= 3 && strncmp (beg, "+OK", 3) == 0) {
                    if (state == STAT) {
                        if (!do_from)
                            write_state_add(&write_state,
                                            from_line, from_line_length);
                        blank_line = 0;
                        if (do_from)
                            state = TOP;
                        else
                            state = RETR;
                    } else if (state == XDELE) {
                        state = QUIT;
                        net_write (s, "QUIT\r\n", 6);
                        if (verbose > 1)
                            fprintf (stderr, "QUIT\r\n");
                        break;
                    } else if (state == DELE) {
                        if (++deleted == count) {
                            state = QUIT;
                            net_write (s, "QUIT\r\n", 6);
                            if (verbose > 1)
                                fprintf (stderr, "QUIT\r\n");
                            break;
                        }
                    } else if (++state == STAT) {
                        if(sscanf (beg + 4, "%u %u", &count, &bytes) != 2)
                            errx(1, "Bad STAT-line: %.*s", (int)(p - beg), beg);
                        if (verbose) {
                            fprintf (stderr, "%u message(s) (%u bytes). "
                                     "fetching... ",
                                     count, bytes);
                            if (do_from)
                                fprintf (stderr, "\n");
                        } else if (do_count) {
                            fprintf (stderr, "%u message(s) (%u bytes).\n",
                                     count, bytes);
                        }
                        if (count == 0) {
                            state = QUIT;
                            net_write (s, "QUIT\r\n", 6);
                            if (verbose > 1)
                                fprintf (stderr, "QUIT\r\n");
                            break;
                        }
                    }

                    rem -= p - beg + 2;
                    beg = p + 2;
                } else {
                    if(state == XDELE) {
                        state = DELE;
                        rem -= p - beg + 2;
                        beg = p + 2;
                    } else
                        errx (1, "Bad response: %.*s", (int)(p - beg), beg);
                }
            }
            if (!do_from)
                write_state_flush (&write_state);

            memmove (in_buf, beg, rem);
            in_len = rem;
            in_ptr = in_buf + rem;
        }
        if (FD_ISSET(s, &writeset)) {
            if ((state == STAT && !do_from) || state == RETR)
                out_len = snprintf (out_buf, sizeof(out_buf),
                                    "RETR %u\r\n", ++asked_for);
            else if ((state == STAT && do_from) || state == TOP)
                out_len = snprintf (out_buf, sizeof(out_buf),
                                    "TOP %u 0\r\n", ++asked_for);
            else if(state == XDELE) {
                out_len = snprintf(out_buf, sizeof(out_buf),
                                   "XDELE %u %u\r\n", 1, count);
                sent_xdele++;
            }
            else if(state == DELE)
                out_len = snprintf (out_buf, sizeof(out_buf),
                                    "DELE %u\r\n", ++asked_deleted);
            if (out_len < 0 || out_len > sizeof(out_buf))
                errx (1, "snprintf failed");
            if (net_write (s, out_buf, out_len) != out_len)
                err (1, "write");
            if (verbose > 1)
                fprintf (stderr, "%s", out_buf);
        }
    }
    if (verbose)
        fprintf (stderr, "Done\n");
    if (do_from) {
        free (tmp);
        free (headers);
    } else {
        write_state_destroy (&write_state);
    }
    return 0;
}

#ifdef KRB5
static int
do_v5 (const char *host,
       int port,
       const char *user,
       const char *filename,
       const char *header_str,
       int leavep,
       int verbose,
       int forkp)
{
    krb5_error_code ret;
    krb5_auth_context auth_context = NULL;
    krb5_principal server;
    int s;

    s = do_connect (host, port, 1);
    if (s < 0)
        return 1;

    ret = krb5_sname_to_principal (context,
                                   host,
                                   "pop",
                                   KRB5_NT_SRV_HST,
                                   &server);
    if (ret) {
        warnx ("krb5_sname_to_principal: %s",
               krb5_get_err_text (context, ret));
        return 1;
    }

    ret = krb5_sendauth (context,
                         &auth_context,
                         &s,
                         "KPOPV1.0",
                         NULL,
                         server,
                         0,
                         NULL,
                         NULL,
                         NULL,
                         NULL,
                         NULL,
                         NULL);
    krb5_free_principal (context, server);
    if (ret) {
        warnx ("krb5_sendauth: %s",
               krb5_get_err_text (context, ret));
        return 1;
    }
    return doit (s, host, user, filename, header_str, leavep, verbose, forkp);
}
#endif

#ifdef HESIOD

#ifdef HESIOD_INTERFACES

static char *
hesiod_get_pobox (const char **user)
{
    void *context;
    struct hesiod_postoffice *hpo;
    char *ret = NULL;

    if(hesiod_init (&context) != 0)
        err (1, "hesiod_init");

    hpo = hesiod_getmailhost (context, *user);
    if (hpo == NULL) {
        warn ("hesiod_getmailhost %s", *user);
    } else {
        if (strcasecmp(hpo->hesiod_po_type, "pop") != 0)
            errx (1, "Unsupported po type %s", hpo->hesiod_po_type);

        ret = estrdup(hpo->hesiod_po_host);
        *user = estrdup(hpo->hesiod_po_name);
        hesiod_free_postoffice (context, hpo);
    }
    hesiod_end (context);
    return ret;
}

#else /* !HESIOD_INTERFACES */

static char *
hesiod_get_pobox (const char **user)
{
    char *ret = NULL;
    struct hes_postoffice *hpo;

    hpo = hes_getmailhost (*user);
    if (hpo == NULL) {
        warn ("hes_getmailhost %s", *user);
    } else {
        if (strcasecmp(hpo->po_type, "pop") != 0)
            errx (1, "Unsupported po type %s", hpo->po_type);

        ret = estrdup(hpo->po_host);
        *user = estrdup(hpo->po_name);
    }
    return ret;
}

#endif /* HESIOD_INTERFACES */

#endif /* HESIOD */

static char *
get_pobox (const char **user)
{
    char *ret = NULL;

#ifdef HESIOD
    ret = hesiod_get_pobox (user);
#endif

    if (ret == NULL)
        ret = getenv("MAILHOST");
    if (ret == NULL)
        errx (1, "MAILHOST not set");
    return ret;
}

static void
parse_pobox (char *a0, const char **host, const char **user)
{
    const char *h, *u;
    char *p;
    int po = 0;

    if (a0 == NULL) {

        *user = getenv ("USERNAME");
        if (*user == NULL) {
            struct passwd *pwd = getpwuid (getuid ());

            if (pwd == NULL)
                errx (1, "Who are you?");
            *user = estrdup (pwd->pw_name);
        }
        *host = get_pobox (user);
        return;
    }

    /* if the specification starts with po:, remember this information */
    if(strncmp(a0, "po:", 3) == 0) {
        a0 += 3;
        po++;
    }
    /* if there is an `@', the hostname is after it, otherwise at the
       beginning of the string */
    p = strchr(a0, '@');
    if(p != NULL) {
        *p++ = '\0';
        h = p;
    } else {
        h = a0;
    }
    /* if there is a `:', the username comes before it, otherwise at
       the beginning of the string */
    p = strchr(a0, ':');
    if(p != NULL) {
        *p++ = '\0';
        u = p;
    } else {
        u = a0;
    }
    if(h == u) {
        /* some inconsistent compatibility with various mailers */
        if(po) {
            h = get_pobox (&u);
        } else {
            u = get_default_username ();
            if (u == NULL)
                errx (1, "Who are you?");
        }
    }
    *host = h;
    *user = u;
}

int
main(int argc, char **argv)
{
    int port = 0;
    int optind = 0;
    int ret = 1;
    const char *host, *user, *filename = NULL;
    char *pobox = NULL;

    setprogname (argv[0]);

#ifdef KRB5
    {
        krb5_error_code ret;

        ret = krb5_init_context (&context);
        if (ret)
            errx (1, "krb5_init_context failed: %d", ret);
    }
#endif

    if (getarg (args, sizeof(args) / sizeof(args[0]), argc, argv,
                &optind))
        usage (1);

    argc -= optind;
    argv += optind;

    if (do_help)
        usage (0);

    if (do_version) {
        print_version(NULL);
        return 0;
    }

    if (do_from && header_str == NULL)
        header_str = "From:";
    else if (header_str != NULL)
        do_from = 1;

    if (do_from) {
        if (argc == 0)
            pobox = NULL;
        else if (argc == 1)
            pobox = argv[0];
        else
            usage (1);
    } else {
        if (argc == 1) {
            filename = argv[0];
            pobox    = NULL;
        } else if (argc == 2) {
            filename = argv[1];
            pobox    = argv[0];
        } else
            usage (1);
    }

    if (port_str) {
        struct servent *s = roken_getservbyname (port_str, "tcp");

        if (s)
            port = s->s_port;
        else {
            char *ptr;

            port = strtol (port_str, &ptr, 10);
            if (port == 0 && ptr == port_str)
                errx (1, "Bad port `%s'", port_str);
            port = htons(port);
        }
    }
    if (port == 0) {
#ifdef KRB5
        port = krb5_getportbyname (context, "kpop", "tcp", 1109);
#else
#error must define KRB5
#endif
    }

    parse_pobox (pobox, &host, &user);

#ifdef KRB5
    if (ret && use_v5) {
        ret = do_v5 (host, port, user, filename, header_str,
                     do_leave, verbose_level, do_fork);
    }
#endif
    return ret;
}