/* Bucky: Gopher <-> HTTP proxy for Bucktooth server */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>

#include <sys/socket.h>
#include <netdb.h>
#include <resolv.h>

#include "gopher.h"
#include "config.h"

#define BUCKDCOM BUCKD" -isproxy -proxy=2F%s -proxyip=%s"
#define BUCKDCOM_MAXLEN 1024

#define HTMLSTR_MAXLEN 512
#define URLSTR_MAXLEN 512

/* Copy and hex encode a string.
 * This will always require hs to be able to hold a string of at least strlen(str) * 2 chars.
 */
void hexstrcpy(char *hs, char *str)
{
	size_t i;

	for (i = 0; str[i]; i++) {
		sprintf(hs + i * 2, "%.2x", str[i]);
	}
}

/* Copy a string, making it HTML-safe */
void htmlstrncpy(char *html, char *str, size_t num)
{
	size_t i, j;

	for (i = 0, j = 0; str[i] && j < num; i++, j++) {
		if (str[i] == '<') {
			strncpy(html + j, "<", 4);
			j += 3;
		} else if (str[i] == '>') {
			strncpy(html + j, ">", 4);
			j += 3;
		} else if (str[i] == ' ') {
			strncpy(html + j, " ", 6);
			j += 5;
		} else if (str[i] == '"') {
			strncpy(html + j, """, 6);
			j += 5;
		} else {
			html[j] = str[i];
		}
	}

	html[j] = '\0';
}

/* Copy a string, making it URL-safe */
void urlstrncpy(char *url, char *str, size_t num)
{
	size_t i, j;

	for (i = 0, j = 0; str[i] && j < num; i++, j++) {
		if (str[i] == '?') {
			strncpy(url + j, "%3F", 3);
			j += 2;
		} else if (str[i] == '\t') {
			strncpy(url + j, "%09", 3);
			j += 2;
		} else if (str[i] == '#') {
			strncpy(url + j, "%23", 3);
			j += 2;
		} else if (str[i] == '<') {
			strncpy(url + j, "%3C;", 3);
			j += 2;
		} else if (str[i] == '>') {
			strncpy(url + j, "%3E", 3);
			j += 2;
		} else if (str[i] == '"') {
			strncpy(url + j, "%22", 3);
			j += 2;
		} else {
			url[j] = str[i];
		}
	}

	url[j] = '\0';
}

/* Copy a URL-safe string, unescaping it */
void unurlstrncpy(char *str, char *url, size_t num)
{
	size_t i, j;

	for (i = 0, j = 0; url[i] && j < num; ++i, ++j) {
		if (url[i] == '+') {
			str[j] = ' ';
		} else if (strncmp(url + i, "%3A", 3) == 0) {
			str[j] = ':';
			i += 2;
		} else if (strncmp(url + i, "%2F", 3) == 0) {
			str[j] = '/';
			i += 2;
		} else {
			str[j] = url[i];
		}
	}

	str[j] = '\0';
}
		
/* Read up to next occurence of character */
int read_to(FILE *buckd, char str[], int n, char to)
{
	int i, c;

	for (i = 0; (c = fgetc(buckd)) != to && i < n; i++) {
		str[i] = c;
	}

	str[i] = '\0';

	return i;
}

/* Print a menu item as HTML */
void print_menu_item(char type, char *display, char *selector, char *host, unsigned port)
{
	char html_display[HTMLSTR_MAXLEN], url_string[URLSTR_MAXLEN];

	/* Escape naughty characters in the display string so it's HTML-friendly */
	htmlstrncpy(html_display, display, HTMLSTR_MAXLEN);

	/* Encode naughty characters in the URL */
	urlstrncpy(url_string, selector, URLSTR_MAXLEN);

	printf("<tr>");

	/* Inline resources (info, error) */
	if (type == GOPHER_ITEM_INFO) {
		printf("<td class=\"info-icon\"></td><td class=\"info\">");
		printf("<tt class=\"info\">");
		if (strcmp(html_display, "") == 0) {
			printf("<br>");
		} else {
			printf("<nobr>%s</nobr>", html_display);
		}
		printf("</tt>");
	} else if (type == GOPHER_ITEM_ERROR) {
		printf("<td class=\"error-icon\">");
		#ifdef GOPHER_ICONS
			printf("<img class=\"icon\" src=\"%s\" alt=\"%s\">", gopher_item_icon(type), gopher_item_icon_alt(type));
		#else
			#ifdef TT_LINKS
				printf("<tt>%s</tt>", gopher_item_icon_alt(type));
			#else
				printf("<div>%s</div>", gopher_item_icon_alt(type));
			#endif
		#endif
		printf("</td><td class=\"error\" valign=\"bottom\">");
		#ifdef TT_LINKS
			printf("<tt class=\"error\">");
		#else
			printf("<div class=\"error\">");
		#endif
		printf("<nobr>%s</nobr>", html_display);
		#ifdef TT_LINKS
			printf("</tt>");
		#else
			printf("</div>");
		#endif
	/* If the resource is external, provide a gopher:// URL */
	} else if (strcmp(host, MY_HOST) != 0 || port != MY_PORT) {
		printf("<td class=\"res-icon\">");
		if (port != DEFAULT_GOPHER_PORT) {
			printf("<a href=\"gopher://%s:%d/%c%s\">", host, port, type, url_string);
		} else {
			printf("<a href=\"gopher://%s/%c%s\">", host, type, url_string);
		}
		#ifdef GOPHER_ICONS
			printf("<img class=\"gicon\" src=\"%s\" alt=\"%s\">", gopher_item_icon(type), gopher_item_icon_alt(type));
		#else
			#ifdef TT_LINKS
				printf("<tt>%s</tt>", gopher_item_icon_alt(type));
			#else
				printf("<div>%s</div>", gopher_item_icon_alt(type));
			#endif
		#endif
		printf("</a></td><td class=\"res\" valign=\"bottom\">");
		#ifdef TT_LINKS
			printf("<tt class=\"res\">");
		#else
			printf("<div class=\"res\">");
		#endif
		if (port != DEFAULT_GOPHER_PORT) {
			printf("<a href=\"gopher://%s:%d/%c%s\">", host, port, type, url_string);
		} else {
			printf("<a href=\"gopher://%s/%c%s\">", host, type, url_string);
		}
		printf("%s", html_display);
		printf("</a>");
		#ifdef TT_LINKS
			printf("</tt>");
		#else
			printf("</div>");
		#endif
	/* Local resources get a relative URI.
	 * If USE_REWRITE is enabled, this is relative to REWRITE_ROOT
	 * otherwise, it is given as a QUERY_STRING to the CGI script
	 */
	} else {
		printf("<td class=\"res-icon\">");
		/* Resources with special URIs */
		if (type == GOPHER_ITEM_TELNET) {
			printf("<a href=\"telnet://%s:%d\">", host, port);
		} else if (type == GOPHER_ITEM_TN3270) {
			printf("<a href=\"tn3270://%s:%d\">", host, port);
		} else if (type == GOPHER_ITEM_HTML && strncmp(url_string, "URL:", 4) == 0) {
			printf("<a href=\"%s\">", url_string + 4);
		} else {
			#ifdef USE_REWRITE
				printf("<a href=\"%s%c%s\">", REWRITE_ROOT, type, url_string);
			#else
				printf("<a href=\"?%c%s\">", type, url_string);
			#endif
		}

		if (type == GOPHER_ITEM_HTML && strncmp(url_string, "URL:", 4) == 0) {
			#ifdef GOPHER_ICONS
				printf("<img class=\"gicon\" src=\"%s\" alt=\"%s\">", GOPHER_ICON_ROOT"/"GOPHER_HTTP_ICON, GOPHER_HTTP_ALT);
			#else
				#ifdef TT_LINKS
					printf("<tt>%s</tt>", GOPHER_HTTP_ALT);
				#else
					printf("<div>%s</div>", GOPHER_HTTP_ALT);
				#endif
			#endif
		#ifdef INLINE_PICS
		} else if (inline_pic(type)) {
			/* No icon */
		#endif
		} else {
			#ifdef GOPHER_ICONS
				printf("<img class=\"gicon\" src=\"%s\" alt=\"%s\">", gopher_item_icon(type), gopher_item_icon_alt(type));
			#else
				#ifdef TT_LINKS
					printf("<tt>%s</tt>", gopher_item_icon_alt(type));
				#else
					printf("<div>%s</div>", gopher_item_icon_alt(type));
				#endif
			#endif
		}

		printf("</a></td><td class=\"res\" valign=\"bottom\">");
		#ifdef TT_LINKS
			printf("<tt class=\"res\">");
		#else
			printf("<div class=\"res\">");
		#endif
		/* Resources with special URIs */
		if (type == GOPHER_ITEM_TELNET) {
			printf("<a href=\"telnet://%s:%d\">", host, port);
		} else if (type == GOPHER_ITEM_TN3270) {
			printf("<a href=\"tn3270://%s:%d\">", host, port);
		} else if (type == GOPHER_ITEM_HTML && strncmp(url_string, "URL:", 4) == 0) {
			printf("<a href=\"%s\">", url_string + 4);
		} else {
			#ifdef USE_REWRITE
				printf("<a href=\"%s%c%s\">", REWRITE_ROOT, type, url_string);
			#else
				printf("<a href=\"?%c%s\">", type, url_string);
			#endif
		}
		#ifdef INLINE_PICS
			if (inline_pic(type)) {
				#ifdef USE_REWRITE
					printf("<img title=\"%s\" src=\"%s%c%s\"", html_display, REWRITE_ROOT,
						type, url_string);
				#else
					printf("<img title=\"%s\" src=\"?%c%s\"", html_display, type, url_string);
				#endif

				#ifdef INLINE_PIC_WIDTH
					printf(" width=\"%d\"", INLINE_PIC_WIDTH);
				#endif

				printf(">");
			} else {
				printf("%s", html_display);
			}
		#else
			printf("%s", html_display);
		#endif

		printf("</a>");

		#ifdef INLINE_SEARCH
			if (type == GOPHER_ITEM_SEARCH) {
				printf(" ");

				#ifdef USE_REWRITE
					printf("<form class=\"search\" action=\"%s\">", REWRITE_ROOT);
				#else
					printf("<form class=\"search\">");
				#endif
				printf("<input type=\"hidden\" name=\"SEARCH\" value=\"%s\">", selector);
				printf("<input type=\"text\" name=\"Q\"> ");
				printf("<input type=\"submit\">");

				printf("</form>");
			}
		#endif

		#ifdef TT_LINKS
			printf("</tt>");
		#else
			printf("</div>");
		#endif
	}

	printf("</td></tr>\r\n");
}

/* Read output from buckd and parse a line of a menu.
 * Returns 1 if there are more lines to parse,
 * or 0 if the end of the menu has been reached.
 */
int handle_menu_line(FILE *buckd)
{
	char display[DISPLAY_MAXLEN];
	char selector[SELECTOR_MAXLEN];
	char host[HOST_MAXLEN];
	char port[PORT_MAXLEN];

	int c;

	char type;

	c = fgetc(buckd);
	if (c == '.' || c == EOF) {
		return 0;
	} else {
		type = c;
	}

	/* Ignore empty/malformed lines */
	if (type == '\n') {
		return 1;
	} else if (!isspace(type)) { 
		read_to(buckd, display, DISPLAY_MAXLEN, '\t');
		read_to(buckd, selector, SELECTOR_MAXLEN, '\t');
		read_to(buckd, host, HOST_MAXLEN, '\t');
		read_to(buckd, port, PORT_MAXLEN, '\r');

		print_menu_item(type, display, selector, host, atoi(port));
	}

	while ((c = fgetc(buckd)) != '\n') if (c == EOF) break;

	return 1;
}

#ifdef SHOW_NAVBARS
/* Optional navigation bar */
void print_top_nav(char type, char *selector)
{
	int len, c;
	int is_root = strcmp(selector, "/") == 0;

	if (is_root) return;

	len = strlen(selector);

	#ifdef TT_LINKS
		printf("<tt class=\"nav\" id=\"topnav\">\r\n");
	#else
		printf("<div class=\"nav\" id=\"topnav\">\r\n");
	#endif

	if (selector[len - 1] == '/') {
		c = len - 2;
	} else {
		c = len - 1;
	}

	while (selector[c] != '/' && c > 0) c--;

	printf("<a id=\"navup\" title=\"go up a directory\" ");
	#ifdef USE_REWRITE
		if (strncmp(selector, "/", c) == 0) {
			printf("href=\"%s\">", REWRITE_ROOT);
		} else {
			printf("href=\"%s1/%.*s\">", REWRITE_ROOT, c, selector);
		}
	#else
		printf("href=\"?1/%.*s\">", c, selector);
	#endif
	#ifdef GOPHER_ICONS
		printf("<img class=\"gicon\" src=\"%s\" alt=\"/\"> ", gopher_item_icon(GOPHER_ITEM_DIRECTORY));
	#endif
	printf("..");
	printf("</a>\r\n");

	printf("<a id=\"navroot\" title=\"go to root of server\" ");
	#ifdef USE_REWRITE
		printf("href=\"%s\">", REWRITE_ROOT);
	#else
		printf("href=\"?\">");
	#endif
	#ifdef GOPHER_ICONS
		printf("<img class=\"gicon\" src=\"%s\" alt=\"/\"> ", gopher_item_icon(GOPHER_ITEM_DIRECTORY));
	#endif
	printf("/");
	printf("</a>\r\n");

	#ifdef HTML_TEXT
	if (type == GOPHER_ITEM_PLAIN_TEXT) {
		printf("<a id=\"navdl\" title=\"download\" ");
		#ifdef USE_REWRITE
			printf("href=\"%s?DOWNLOAD=%s\">", REWRITE_ROOT, selector);
		#else
			printf("href=\"?DOWNLOAD=%s\">", selector);
		#endif
		#ifdef GOPHER_ICONS
			printf("<img class=\"gicon\" src=\"%s\" alt=\"->\"> ", gopher_item_icon(type));
		#endif
		printf("download");
		printf("</a>\r\n");
	}
	#endif

	custom_navbar_top(type, selector);

	#ifdef TT_LINKS
		printf("</tt>\r\n");
	#else
		printf("</div>\r\n");
	#endif

	printf("<hr>\r\n");
}

void print_bottom_nav(char type, char *selector)
{
	char url[URLSTR_MAXLEN];
	int is_root = strcmp(selector, "/") == 0;

	urlstrncpy(url, selector, URLSTR_MAXLEN);

	printf("<hr>\r\n");

	#ifdef TT_LINKS
		printf("<tt class=\"nav\" id=\"bottomnav\">\r\n");
	#else
		printf("<div class=\"nav\" id=\"bottomnav\">\r\n");
	#endif

	if (is_root) {
		if (MY_PORT == DEFAULT_GOPHER_PORT) {
			printf("<a href=\"gopher://%s\" title=\"view with Gopher client\">", MY_HOST);
		} else {
			printf("<a href=\"gopher://%s:%d\" title=\"view with Gopher client\">", MY_HOST, MY_PORT);
		}
	} else {
		if (MY_PORT == DEFAULT_GOPHER_PORT) {
			printf("<a href=\"gopher://%s/%c/%s\" title=\"view with Gopher client\">", MY_HOST, type, url);
		} else {
			printf("<a href=\"gopher://%s:%d/%c/%s\" title=\"view with Gopher client\">", MY_HOST, MY_PORT, type, url);
		}
	}

	#ifdef GOPHER_ICONS
		printf("<img class=\"gicon\" src=\"%s\" alt=\"/\"> ", gopher_item_icon(GOPHER_ITEM_DIRECTORY));
	#endif

	if (is_root) {
		if (MY_PORT == DEFAULT_GOPHER_PORT) {
			printf("gopher://%s", MY_HOST);
		} else {
			printf("gopher://%s:%d", MY_HOST, MY_PORT);
		}
	} else {
		if (MY_PORT == DEFAULT_GOPHER_PORT) {
			printf("gopher://%s/%c/%s", MY_HOST, type, url);
		} else {
			printf("gopher://%s:%d/%c/%s", MY_HOST, MY_PORT, type, url);
		}
	}

	printf("</a>\r\n");

	custom_navbar_bottom(type, selector);

	#ifdef TT_LINKS
		printf("</tt>\r\n");
	#else
		printf("</div>\r\n");
	#endif
}
#endif

/* Textfiles (plain text, type 0) will have a final full-stop (.) line */
void handle_textfile(FILE* buckd, int esc)
{
	int c, i;
	int next[3];

	while ((c = fgetc(buckd)) != EOF) {
		if (c == '.') {
			for (i = 0; i < 3; i++) {
				next[i] = fgetc(buckd);
			}

			if (next[0] == '\r' && next[1] == '\n' && next[2] == EOF) {
				break;
			} else {
				for (i = 2; i >= 0; i--) {
					ungetc(next[i], buckd);
				}
			}
		}

		if (esc) {
			switch (c) {
				case '<': printf("<"); break;
				case '>': printf(">"); break;
				default: putchar(c); break;
			}
		} else {
			putchar(c);
		}
	}
}

/* Files should be sent as-is with an appropriate MIME type */
void handle_file(FILE *buckd, char response_type, char *selector, int download)
{
	int c;

	char *ext;

	printf("Content-type: ");

	/* for binary and Gopher+ Picture/Movie/Sound, attempt to guess the MIME type from the extension */
	if (response_type == GOPHER_ITEM_BINARY ||
	    response_type == GOPHER_ITEM_MOVIE ||
	    response_type == GOPHER_ITEM_PICTURE ||
	    response_type == GOPHER_ITEM_SOUND)
	{
		ext = strrchr(selector, '.');
		if (!ext) ext = "";
		printf("%s; charset=binary", mime_type_from_ext(ext));
	} else {
		printf("%s; charset=utf-8", mime_type(response_type));
	}

	printf("\r\n");

	if (download) {
		char *fname;
		fname = strrchr(selector, '/');
		fname = fname ? fname + 1 : selector;
		printf("Content-disposition: attachment; filename=\"%s\"\r\n", fname);
	}

	printf("\r\n");

	if (response_type == GOPHER_ITEM_PLAIN_TEXT || response_type == GOPHER_ITEM_XML) {
		/* Do not show the final terminating full-stop returned by the server */
		handle_textfile(buckd, 0);
	} else {
		while ((c = fgetc(buckd)) != EOF) {
			putchar(c);
		}
	}
}

/* Handle output from buckd based on the item type and selector requested */
void handle_buckd(FILE *buckd, char response_type, char *selector, int download)
{
	#ifdef HTML_TEXT
	if (response_type == GOPHER_ITEM_DIRECTORY || response_type == GOPHER_ITEM_SEARCH || (response_type == GOPHER_ITEM_PLAIN_TEXT && !download)) {
	#else
	if (response_type == GOPHER_ITEM_DIRECTORY || response_type == GOPHER_ITEM_SEARCH) {
	#endif
		printf("Content-type: text/html; charset=utf-8\r\n\r\n");
		printf("<html>\r\n");
		printf("<head>\r\n");
		printf("<meta charset=\"utf-8\">\r\n");
		printf("<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">\r\n");

		#ifdef EXTERNAL_CSS
			printf("<link rel=\"stylesheet\" type=\"text/css\" href=\"%s\">", EXTERNAL_CSS);
		#endif

		if (strcmp(selector, "/") == 0)
			printf("<title>%s</title>\r\n", MY_HOST);
		else
			printf("<title>%s/%c/%s</title>\r\n", MY_HOST, response_type, selector);

		printf("</head>\r\n");
		printf("<body>\r\n");

		#ifdef SHOW_NAVBARS
			print_top_nav(response_type, selector);
		#endif

		#ifdef HTML_TEXT
		if (response_type == GOPHER_ITEM_PLAIN_TEXT) {
			printf("<pre>");
			handle_textfile(buckd, 1);
			printf("</pre>");
		} else
		#endif
		if (response_type == GOPHER_ITEM_DIRECTORY || strstr(selector, "\t") || strstr(selector, "?")) {
			printf("<table border=\"0\" cellpadding=\"1\" cellspacing=\"0\">\r\n");
			while (handle_menu_line(buckd));
			printf("</table>\r\n");
		} else {
			printf("<tt class=\"queryTitle\">Enter query:</tt>\r\n");
			#ifdef USE_REWRITE
				printf("<form action=\"%s\">\r\n", REWRITE_ROOT);
			#else
				printf("<form>\r\n");
			#endif
			printf("<input type=\"hidden\" name=\"SEARCH\" value=\"%s\">\r\n", selector);
			printf("<input type=\"text\" name=\"Q\" autofocus>\r\n");
			printf("<input type=\"submit\">\r\n");
			printf("</form>\r\n");
		}

		#ifdef SHOW_NAVBARS
			print_bottom_nav(response_type, selector);
		#endif

		printf("</body>\r\n");
		printf("</html>\r\n");
	} else {
		handle_file(buckd, response_type, selector, download);
	}
}		

/* Call Bucktooth daemon and return a FILE pointer to the process */
FILE *popen_buckd(char *req)
{
	char *ip = getenv("REMOTE_ADDR");
	char com[BUCKDCOM_MAXLEN];

	snprintf(com, BUCKDCOM_MAXLEN, BUCKDCOM, req, ip);

	return popen(com, "r");
}

FILE *open_socket(char *req)
{
	int sockfd;
	struct sockaddr_in addr;
	struct hostent *server;

	sockfd = socket(AF_INET, SOCK_STREAM, 0);

	server = gethostbyname(MY_HOST);

	addr.sin_family = AF_INET;
	addr.sin_port = htons(MY_PORT);

	bcopy(server->h_addr, &addr.sin_addr.s_addr, server->h_length);

	connect(sockfd, (struct sockaddr *) &addr, sizeof(addr));

	if (write(sockfd, req, strlen(req)) == -1) {
		return NULL;
	}
	if (write(sockfd, "\r\n", 2) == -1) {
		return NULL;
	}

	return fdopen(sockfd, "r");
}

int main(void)
{
	char *query_string, *type, *selector, *search_res, *search_q;
	char search_sel[SELECTOR_MAXLEN], search_params[URLSTR_MAXLEN];
	#ifndef USE_SOCKETS
	char hs[SELECTOR_MAXLEN * 2];
	#endif
	FILE *fp;
	int download = 0;

	/* QUERY_STRING will be in the form of #/SELECTOR */
	query_string = getenv("QUERY_STRING");

	/* ...EXCEPT if its a special SEARCH query (needed to use standard HTML form for queries) */
	if (strncmp(query_string, "SEARCH=", 7) == 0) {
		type = "7";
		search_res = strtok(query_string + 7, "&");
		strtok(NULL, "=");
		search_q = strtok(NULL, "");
		if (!search_q) search_q = "";
		unurlstrncpy(search_params, search_q, URLSTR_MAXLEN);
		snprintf(search_sel, SELECTOR_MAXLEN, "%s\t%s", search_res, search_params);
		selector = search_sel;
	#ifdef HTML_TEXT
	/* ... or the special DOWNLOAD action (for text files displayed as HTML) */
	} else if (strncmp(query_string, "DOWNLOAD=", 9) == 0) {
		type = "0";
		search_res = strtok(query_string + 9, "");
		unurlstrncpy(search_params, search_res, URLSTR_MAXLEN);
		snprintf(search_sel, SELECTOR_MAXLEN, "%s", search_res);
		selector = search_sel;
		download = 1;
	#endif
	} else {
		type = strtok(query_string, "/");
		selector = strtok(NULL, "");
	}

	/* Default to root menu */
	if (!type) type = "1";
	if (!selector) selector = "/";

	#ifdef USE_SOCKETS
		fp = open_socket(selector);
		handle_buckd(fp, *type, selector, download);
		fclose(fp);
	#else
		/* buckd's -proxy flag takes a hex-encoded selector */
		hexstrcpy(hs, selector);

		fp = popen_buckd(hs);
		handle_buckd(fp, *type, selector, download);
		pclose(fp);
	#endif
	
	return 0;
}