vger/main.c

#include "vger.c"

int
main(int argc, char **argv)
{
	char 		request  [GEMINI_REQUEST_MAX] = {'\0'};
	char 		user     [_SC_LOGIN_NAME_MAX] = "";
	char 		hostname [GEMINI_REQUEST_MAX] = {'\0'};
	char 		query    [PATH_MAX] = {'\0'};
	char 		chroot_dir[PATH_MAX] = DEFAULT_CHROOT;
	char 		file     [FILENAME_MAX] = DEFAULT_INDEX;
	char 		dir      [PATH_MAX] = {'\0'};
	char           *pos = NULL;
	int 		option = 0;
	int 		virtualhost = 0;
	int 		docgi = 0;

	/*
	 * request : contain the whole request from client : gemini://...\r\n
	 * user : username, used in drop_privileges()
	 * hostname : extracted from hostname. used with virtualhosts and cgi SERVER_NAME
	 * query : file requested in cgi : gemini://...?query
	 * file : file basename to display. Emtpy is a directory has been requested
	 * dir : directory requested. vger will chdir() in to find file
	 * pos : used to parse request and split into interesting parts
	 */

	while ((option = getopt(argc, argv, ":d:l:m:u:c:vi")) != -1) {
		switch (option) {
		case 'd':
			estrlcpy(chroot_dir, optarg, sizeof(chroot_dir));
			break;
		case 'l':
			estrlcpy(lang, "lang=", sizeof(lang));
			estrlcat(lang, optarg, sizeof(lang));
			break;
		case 'm':
			estrlcpy(default_mime, optarg, sizeof(default_mime));
			break;
		case 'u':
			estrlcpy(user, optarg, sizeof(user));
			break;
		case 'c':
			estrlcpy(cgidir, optarg, sizeof(cgidir));
			docgi = 1;
			break;
		case 'v':
			virtualhost = 1;
			break;
		case 'i':
			doautoidx = 1;
			break;
		}
	}

	/*
	 * do chroot if an user is supplied
	 */
	drop_privileges(user, chroot_dir);

	/*
	 * read 1024 chars from stdin
	 * to get the request
	 * (actually 1024 + \0)
	 */
	if (fgets(request, GEMINI_REQUEST_MAX, stdin) == NULL) {
		/* EOF reached before reading anything */
		if (feof(stdin)) {
			status(59, "request is too short and probably empty");
			errlog("request is too short and probably empty");

			/* error before reading anything */
		} else if (ferror(stdin)) {
			status(59, "Error while reading request");
			errlog("Error while reading request: %s", request);
		}
	}
	/* check if string ends with '\n', or to long */
	if (request[strnlen(request, GEMINI_REQUEST_MAX) - 1] != '\n') {
		status(59, "request is too long (1024 max)");
		errlog("request is too long (1024 max): %s", request);
	}
	/* remove \r\n at the end of string */
	pos = strchr(request, '\r');
	if (pos != NULL)
		*pos = '\0';

	/*
	 * check if the beginning of the request starts with
	 * gemini://
	 */
	if (strncmp(request, "gemini://", GEMINI_PART) != 0) {
		/* error code url malformed */
		errlog("request «%s» doesn't match gemini://",
		       request);
	}
	syslog(LOG_DAEMON, "request %s", request);

	/* remove the gemini:// part */
	memmove(request, request + GEMINI_PART, strlen(request) + 1 - GEMINI_PART);

	/* remove all "/.." for safety reasons */
	while ((pos = strstr(request, "/..")) != NULL)
	    memmove(request, pos + 3, strlen(pos) + 1 - 3);	/* "/.." = 3 */

	/* look for hostname in request : first thing before first / if any */
	pos = strchr(request, '/');
	if (pos != NULL) {
		/* copy what's after hostname in dir */
		estrlcpy(dir, pos, strlen(pos) + 1);
		/* just keep hostname in request : stop the string with \0 */
		pos[0] = '\0';
	}
	/* check if client added :port at end of hostname and remove it */
	pos = strchr(request, ':');
	if (pos != NULL) {
		/* end string at : */
		pos[0] = '\0';
	}
	/* copy hostname from request */
	estrlcpy(hostname, request, sizeof(hostname));

	/* remove leading '/' in dir */
	while (dir[0] == '/')
	    memmove(dir, dir + 1, strlen(dir + 1) + 1);

	if (virtualhost) {
		/* add hostname at the beginning of the dir path */
		char 		tmp      [PATH_MAX] = {'\0'};
		estrlcpy(tmp, hostname, sizeof(tmp));
		estrlcat(tmp, "/", sizeof(tmp));
		estrlcat(tmp, dir, sizeof(tmp));
		estrlcpy(dir, tmp, sizeof(dir));
	}

	/* remove a query string before percent decoding */
	/* look for "?" if any to set query for cgi, remove it */
	pos = strchr(dir, '?');
	if (pos != NULL) {
		estrlcpy(query, pos + 1, sizeof(query));
		uridecode(query);
		pos[0] = '\0';
	}

	/* percent decode */
	uridecode(dir);

	/*
	 * split dir and filename. file is last part after last '/'. if none
	 * found, then requested file is actually a directory
	 */
	if (strlen(dir) > 0) {
		/*
		 * if in cgidir, only the first file after cgidir/FILE is to be executed
		 * the rest is PATH_INFO
		 */
		/* find the string of cgidir without chroot_dir prefix */
		char	tmp [PATH_MAX] = {'\0'};
		char	*cgipp;
		strip_trailing_slash(chroot_dir);
		strip_trailing_slash(cgidir);
		estrlcpy(tmp, cgidir + strlen(chroot_dir), sizeof(tmp));
		cgipp = tmp;
		if (tmp[0] == '/')
			cgipp++;

		if (docgi && strncmp(dir, cgipp, strlen(cgipp)) == 0) {
			pos = strchr(dir+strlen(cgipp), '/');
		} else {
			pos = strrchr(dir, '/');
		}
		if (pos != NULL) {
			estrlcpy(file, pos + 1, sizeof(file));	/* +1 : no leading '/' */
			pos[0] = '\0';

			/* change directory to requested directory */
			if (strlen(dir) > 0)
			    echdir(dir);
		} else {
			estrlcpy(file, dir, sizeof(file));
		}
	}
	if (docgi) {
		/* check if directory is cgidir */
		char 		cgifp    [PATH_MAX] = {'\0'};
		estrlcpy(cgifp, chroot_dir, sizeof(cgifp));
		if (cgifp[strlen(cgifp) - 1] != '/')
		    estrlcat(cgifp, "/", sizeof(cgifp));

		estrlcat(cgifp, dir, sizeof(cgifp));

		/* not cgipath, display file content */
		if (strcmp(cgifp, cgidir) != 0)
			goto file_to_stdout;

		/* set env variables for CGI */
		/*
		 * see
		 * https://lists.orbitalfox.eu/archives/gemini/2020/000315.htm
		 * l
		 */
		esetenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
		esetenv("SERVER_PROTOCOL", "GEMINI", 1);
		esetenv("SERVER_SOFTWARE", "vger/1", 1);

		if (*query)
			esetenv("QUERY_STRING", query, 1);

		/* if we've got here and file contains a '/', it should be interpreted as PATH_INFO */
		pos = strchr(file, '/');
		if (pos != NULL) {
			setenv("PATH_INFO", pos, 1);
			pos[0] = '\0';	/* keep only script name */
		}
		esetenv("SCRIPT_NAME", file, 1);
		esetenv("SERVER_NAME", hostname, 1);

		cgi(file);
		return 0;
	}
file_to_stdout:
	/* regular file  to stdout */
	display_file(file);

	return (0);
}