/*
 *  nntp.c: NNTP library (implementation)
 *
 *  Copyright (c) 2001 The OSSP Project (http://www.ossp.org/)
 *  Copyright (c) 2001 Cable & Wireless Deutschland (http://www.cw.com/de/)
 *
 *  This file is part of OSSP lmtp2nntp, an NNTP speaking local
 *  mailer which forwards mails as Usenet news articles via NNTP.
 *  It can be found at http://www.ossp.com/pkg/lmtp2nntp/.
 *
 *  Permission to use, copy, modify, and distribute this software for
 *  any purpose with or without fee is hereby granted, provided that
 *  the above copyright notice and this permission notice appear in all
 *  copies.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 AUTHORS AND COPYRIGHT HOLDERS AND THEIR
 *  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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <errno.h>

#include "nntp.h"

/* maximum NNTP protocol line length */
#define NNTP_LINE_MAXLEN 1024

typedef struct {
    int   rl_cnt;
    char *rl_bufptr;
    char  rl_buf[NNTP_LINE_MAXLEN];
} nntp_readline_t;

struct nntp_st {
    int             rfd;
    int             wfd;
    nntp_io_t       io;
    nntp_readline_t rl; 
};

nntp_t *nntp_create(int rfd, int wfd, nntp_io_t *io)
{
    nntp_t *nntp;

    if ((nntp = (nntp_t *)malloc(sizeof(nntp_t))) == NULL) 
        return NULL;

    if (io == NULL) {
        nntp->io.read  = read;
        nntp->io.write = write;
    } else {
        nntp->io.read  = io->read  ? io->read  : read;
        nntp->io.write = io->write ? io->write : write;
    }

    nntp->rfd = rfd;
    nntp->wfd = wfd;
    nntp->rl.rl_cnt = 0;
    nntp->rl.rl_bufptr = NULL;
    nntp->rl.rl_buf[0] = '\0';

    return nntp;
}

void nntp_destroy(nntp_t *nntp)
{
    if (nntp != NULL)
        free(nntp);
    return;
}

nntp_rc_t nntp_readline(nntp_t *nntp, char *buf, size_t buflen)
{
    /* read a line (characters until NL) from input stream */
    size_t n;
    char c;
    nntp_readline_t *rl = &nntp->rl;

    if (nntp == NULL)
        return NNTP_ERR_ARG;
    for (n = 0; n < buflen-1;) {

        /* fetch one character (but read more) */
        if (rl->rl_cnt <= 0) {
            do {
                rl->rl_cnt = nntp->io.read(nntp->rfd, rl->rl_buf, NNTP_LINE_MAXLEN);
            } while (rl->rl_cnt == -1 && errno == EINTR);
            if (rl->rl_cnt == -1)
                return NNTP_ERR_SYSTEM;
            if (rl->rl_cnt == 0)
                return NNTP_EOF;
            rl->rl_bufptr = rl->rl_buf;
        }

        /* act on fetched character */
        rl->rl_cnt--;
        c = *rl->rl_bufptr++;
        if (c == '\r')
            continue;       /* skip copying CR */
        if (c == '\n')
            break;          /* end of line */
        buf[n++] = c;       /* output char into given buffer */

    }
    buf[n] = '\0';          /* string termination */
    if (n == (buflen-1)) 
        return NNTP_ERR_OVERFLOW;
    return NNTP_OK;
}

nntp_rc_t nntp_writeline(nntp_t *nntp, char *buf)
{
    char tmp[NNTP_LINE_MAXLEN];

    if (nntp == NULL)
        return NNTP_ERR_ARG;
    strncpy(tmp, buf, NNTP_LINE_MAXLEN-3);
    strcat(tmp, "\r\n");
    if (nntp->io.write(nntp->wfd, tmp, strlen(tmp)) < 0)
        return NNTP_ERR_SYSTEM;
    return NNTP_OK;
}

nntp_rc_t nntp_post(nntp_t *nntp, char *msg)
{
    nntp_rc_t rc = NNTP_OK;
    char line[NNTP_LINE_MAXLEN];

    if ((rc = nntp_readline(nntp, line, sizeof(line))) != NNTP_OK)
        return rc;
    fprintf(stderr, "READ:<%s>\n", line);
    if ((rc = nntp_writeline(nntp, "mode reader")) != NNTP_OK)
        return rc;
    fprintf(stderr, "WRITE:<mode reader>\n");
    if ((rc = nntp_readline(nntp, line, sizeof(line))) != NNTP_OK)
        return rc;
    fprintf(stderr, "READ:<%s>\n", line);
    if ((rc = nntp_writeline(nntp, "quit")) != NNTP_OK)
        return rc;
    fprintf(stderr, "WRITE:<quit>\n");
    if ((rc = nntp_readline(nntp, line, sizeof(line))) != NNTP_OK)
        return rc;
    fprintf(stderr, "READ:<%s>\n", line);

    return rc;
}

char *nntp_error(nntp_t *nntp, nntp_rc_t rc)
{
    char *str;
                                      str = "NNTP: errorcode has no description";
    if      (rc == NNTP_OK          ) str = "NNTP: no error";
    else if (rc == NNTP_EOF         ) str = "NNTP: end of file";
    else if (rc == NNTP_ERR_SYSTEM  ) str = "NNTP: see errno";
    else if (rc == NNTP_ERR_ARG     ) str = "NNTP: invalid argument";
    else if (rc == NNTP_ERR_OVERFLOW) str = "NNTP: buffer overflow";
    return str;
}