/* $Id: nntpgrab.c,v 1.2 2005/09/11 17:18:18 bjk Exp $ */
/*
 * Connect to an NNTP server and grab the specified article by Message_ID. The
 * server and port may be specified on the command line or gotten from the
 * NNTPSERVER environment variable.
 *
 * $Log: nntpgrab.c,v $
 * Revision 1.2  2005/09/11 17:18:18  bjk
 * Treat response codes 500 and 503 as server unavailable.
 *
 * Revision 1.1  2005/06/02 19:13:45  bjk
 * Initial commit.
 *
 *
 * Ben Kibbey <bjk@arbornet.org>
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <limits.h>

#define NNTPPORT	119
#define BUFFER_SIZE	256

int debug;
int sfd;
char *username, *password;

void usage(const char *pn)
{
    printf("Usage: %s [-hkd] [-s <server> [-p <port]] [-u <user> -e <pass>] <Message_ID> [...]\n", pn);
    printf("    -s  Server to connect to. Default is $NNTPSERVER.\n");
    printf("    -p  Server port. Default is %i.\n", NNTPPORT);
    printf("    -k  Don't strip any CTRL-LF from the article.\n");
    printf("    -u  Authenticate username.\n");
    printf("    -e  Password to authenticate user.\n");
    printf("    -d  Enable debugging.\n");
    printf("    -h  This help text.\n");
    exit(EXIT_FAILURE);
}

int send_to_server(int fd, const char *str)
{
    size_t n;

    if ((n = send(fd, str, strlen(str), 0)) != strlen(str)) {
	warn("send()");
	return 1;
    }

    if (debug)
	fprintf(stderr, "%i >> '%s'\n", n, str);

    return 0;
}

int grab_article(FILE *fp, char *msgid, int strip)
{
    struct timeval tv;
    int article_len = 0;
    int requested_article = 0;
    char *article = NULL;
    static int once;

    while (1) {
	fd_set r_fds, w_fds;
	char buf[BUFFER_SIZE];
	int len = 0, n;
	char *p;
	int resp;

	FD_ZERO(&w_fds);
	FD_ZERO(&r_fds);
	FD_SET(sfd, &w_fds);
	FD_SET(sfd, &r_fds);
	tv.tv_sec = 0;
	tv.tv_usec = 300000;

	if ((n = select(sfd + 1, &r_fds, &w_fds, NULL, &tv)) > 0) {
	    if (once)
		goto next_article;

	    if (FD_ISSET(sfd, &r_fds)) {
		while ((p = fgets(buf, sizeof(buf), fp)) != NULL) {
		    len = strlen(p);

		    if (requested_article) {
			/* End of article. */
			if (len >= 3 && ((p[0] == '.' && p[1] == '\r' && p[2] == '\n') ||
				(p[0] == '.' && p[1] == '.' && p[2] == '\r' && p[2] == '\n'))) {
			    printf("%s", article);
			    free(article);
			    once = 1;
			    return EXIT_SUCCESS;
			}
			else {
			    article_len += len + 1;

			    if ((article = realloc(article, article_len * sizeof(char))) == NULL)
				err(EXIT_FAILURE, "realloc()");

			    if (strip) {
				p[strlen(p) - 2] = '\n';
				p[strlen(p) - 1] = '\0';
			    }

			    strcat(article, p);
			    article[article_len - 1] = '\0';
			}

			continue;
		    }
		    else {
			if (debug)
			    fprintf(stderr, "%i << %s\n", len, buf);

			p[3] = '\0';
			resp = atoi(p);
			p[3] = ' ';
		    }

		    if (resp == 200 || resp == 201) {
authenticate:
			if (username) {
			    snprintf(buf, sizeof(buf), "AUTHINFO USER %s\r\n", username);

			    if (send_to_server(sfd, buf) != 0) {
				fprintf(stderr, "closing connection\n");
				return EXIT_FAILURE;
			    }

			    continue;
			}
next_article:
			if (debug)
			    fprintf(stderr, "Fetching article %s ...\n", msgid);

			snprintf(buf, sizeof(buf), "ARTICLE %s\r\n", msgid);

			if (send_to_server(sfd, buf) != 0) {
			    fprintf(stderr, "closing connection\n");
			    return EXIT_FAILURE;
			}
		    }
		    else if (resp >= 420 && resp < 430) {
			fprintf(stderr, "Invalid article syntax \"%s\".\n", msgid);
			return EXIT_FAILURE;
		    }
		    else if (resp >= 430 && resp < 440) {
			fprintf(stderr, "No such article \"%s\".\n", msgid);
			return EXIT_FAILURE;
		    }
		    else if (resp >= 220 && resp < 230) {
			requested_article = 1;
			article_len = 0;
		    }
		    else if (resp == 205) {
			return EXIT_SUCCESS;
		    }
		    else if (resp == 281) {
			if (debug)
			    fprintf(stderr, "Successfully authenticated.\n");

			goto next_article;
		    }
		    else if (resp == 480) {
			if (!username) {
			    fprintf(stderr, "Authorization required.\n");
			    return EXIT_FAILURE;
			}

			goto authenticate;
		    }
		    else if (resp >= 410 && resp < 420) {
			fprintf(stderr, "Not in a newsgroup (invalid article \"%s\"?).\n", msgid);
			return EXIT_FAILURE;
		    }
		    else if (resp == 482) {
			fprintf(stderr, "Authentication for user \"%s\" rejected.\n", username);
			return EXIT_FAILURE;
		    }
		    else if (resp == 502) {
			fprintf(stderr, "Failed to authenticate user \"%s\".\n", username);
			return EXIT_FAILURE;
		    }
		    else if (resp == 503 || resp == 500) {
			fprintf(stderr, "Server unavailable?\n");
			return EXIT_FAILURE;
		    }
		    else if (resp == 381) {
			snprintf(buf, sizeof(buf), "AUTHINFO PASS %s\r\n", password);

			if (send_to_server(sfd, buf) != 0) {
			    fprintf(stderr, "closing connection\n");
			    return EXIT_FAILURE;
			}

			continue;
		    }
		}

		if (len < 0)
		    warn("recv()");
	    }
	}
	else
	    printf("timeout\n");
    }

    return EXIT_SUCCESS;
}

int main(int argc, char *argv[])
{
    int opt;
    struct sockaddr_in d_addr;
    char *host = NULL;
    int port = NNTPPORT;
    struct hostent *he;
    int ret = EXIT_SUCCESS;
    char buf[LINE_MAX], *p;
    FILE *fp;
    int strip = 1;
    char *tmp;

    host = getenv("NNTPSERVER");

    if ((tmp = strchr(host, ':')) != NULL) {
	tmp++;
	port = atoi(tmp);
	host[strlen(host) - strlen(tmp) - 1] = '\0';
    }

    while ((opt = getopt(argc, argv, "u:e:dkhs:p:")) != -1) {
	switch (opt) {
	    case 'u':
		username = strdup(optarg);
		break;
	    case 'e':
		password = strdup(optarg);
		break;
	    case 'k':
		strip = 0;
		break;
	    case 'd':
		debug = 1;
		break;
	    case 's':
		host = strdup(optarg);
		break;
	    case 'p':
		port = atoi(optarg);
		break;
	    case 'h':
	    default:
		usage(argv[0]);
	}
    }

    if (!host || (username && !password))
	usage(argv[0]);

    if ((sfd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
	err(EXIT_FAILURE, "socket()");

    if ((fp = fdopen(sfd, "rw")) == NULL)
	err(EXIT_FAILURE, "fdopen()");

    memset(&d_addr, '\0', sizeof(struct sockaddr_in));
    d_addr.sin_family = AF_INET;
    d_addr.sin_port = htons(port);

    if ((he = gethostbyname(host)) == NULL)
	errx(EXIT_FAILURE, "gethostbyname() failed.");

    d_addr.sin_addr = *((struct in_addr *)he->h_addr);

    if (debug)
	fprintf(stderr, "Connecting to %s ...\n", host);

    if (connect(sfd, (struct sockaddr *)&d_addr, sizeof(struct sockaddr)) == -1)
	err(EXIT_FAILURE, "connect()");

    if (debug)
	fprintf(stderr, "Connected.\n");

    if (optind == argc) {
	while ((p = fgets(buf, sizeof(buf), stdin)) != NULL) {
	    buf[strlen(buf) - 1] = '\0';
	    ret |= grab_article(fp, buf, strip);
	}
    }
    else {
	for (; optind < argc; optind++)
	    ret |= grab_article(fp, argv[optind], strip);
    }

    close(sfd);
    exit(ret);
}