vger/main.c

/*
 * Copyright (c) 2020 Solène Rapenne <solene@openbsd.org>
 * 
 * MIT LICENSE
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * 
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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 <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <errno.h>

#define BUFF_LEN_1	 1000
#define BUFF_LEN_2	 1025
#define BUFF_LEN_3	 1024
#define GEMINI_PART	 9
#define DEFAULT_CHROOT	"/var/gemini/"

void			 ok_status(void);
void			 err_status(void);
void			 display_file(char *);

int			 main(int, char **);

void
ok_status(void)
{
	printf("20 text/gemini; lang=en\r\n");
}

void
err_status(void)
{
	printf("40 text/gemini; lang=en\r\n");
}

void
display_file(char *path)
{
	size_t buflen = BUFF_LEN_1;
	char *buffer[BUFF_LEN_1];
	ssize_t nread;
	struct stat sb;

	// this is to check if path is a directory
    	stat(path, &sb);

	FILE *fd = fopen(path, "r");

	if (fd != NULL && S_ISDIR(sb.st_mode) != 1) {

        	// check if directory
		ok_status();

		/* read the file and write it to stdout */
		while ((nread = fread(buffer, sizeof(char), buflen, fd)) != 0)
			fwrite(buffer, sizeof(char), nread, stdout);
		fclose(fd);
	} else {
		err_status();
		/*
		 * fprintf(stderr, "can't open %s %ld: %s\n", path,strlen(path),
		 *     strerror(errno));
		 */
	}

}

int
main(int argc, char **argv)
{
	char buffer[BUFF_LEN_2];
	char request[BUFF_LEN_2];
	char hostname[BUFF_LEN_2];
	char file[BUFF_LEN_2];
	char path[BUFF_LEN_2] = "";
	int option;
	char *pos;

	while((option = getopt(argc, argv, ":d:")) != -1)
	{
    		switch(option)
    		{
        		case 'd':
        			strlcpy(path, optarg, sizeof(path));
        			break;
    		}
	}
	if(strlen(path) == 0)
    		strlcpy(path, DEFAULT_CHROOT, sizeof(DEFAULT_CHROOT));

#ifdef __OpenBSD__
	if (unveil(path, "r") == -1)
		err(1, "unveil");

	if (pledge("stdio rpath", NULL) == -1)
		err(1, "pledge");
#endif

	/*
	 * read 1024 chars from stdin
	 * to get the request
	 */
	fgets(request, BUFF_LEN_3, stdin);

	/* remove \r\n at the end of string */
	pos = strchr(request, '\r');
	if(pos != NULL)
        	strlcpy(pos, "\0", 1);

	/*
	 * check if the beginning of the request starts with
	 * gemini://
	 */
	int start_with_gemini = strncmp(request, "gemini://", 9);

	/* the request must start with gemini:// */
	if(start_with_gemini != 0) {
		/* error code url malformed */
		printf("request «%s» doesn't match gemini:// at index %i",
		    request, start_with_gemini);
		exit(1);
	}

	/* remove the gemini:// part */
	strlcpy(buffer, request + GEMINI_PART, sizeof(buffer) - GEMINI_PART);
	strlcpy(request, buffer, sizeof(request));

	/*
	 * look for the first / after the hostname
	 * in order to split hostname and uri
	 */
	pos = strchr(request, '/');

	if (pos != NULL) {
		/* if there is a / found */
		int position = -1;
		for (int i = 0; i < sizeof(request); i++) {
			if (*pos == request[i]) {
				position = i;
				break;
			}
		}

		/* separate hostname and uri */
		if (position != -1) {
			strlcpy(hostname, request, position);
			strlcpy(file, request + position + 1, sizeof(request));

			/* use a default file if no file are requested
                         * this can happen in two cases
                         * gemini://hostname/
                         * gemini://hostname/directory/
                         */
			if(strlen(file) == 0)
				strlcpy(file, "/index.gmi", 11);
			if(file[strlen(file)-1] == '/')
    				strlcat(file, "index.gmi", sizeof(file));

		} else {
			puts("error undefined");
			exit(2);
		}
	} else {
		/*
		 * there are no slash / in the request
		 * -2 to remove \r\n
		*/
		strlcpy(hostname, request, sizeof(hostname));
		strlcpy(file, "/index.gmi", 11);
	}

	/* add the base dir to the file requested */
	strlcat(path, file, sizeof(path));

	/* open file and send it to stdout */
	display_file(path);

	return(0);
}