/*
 * OpenConnect (SSL + DTLS) VPN client
 *
 * Copyright © 2008-2015 Intel Corporation.
 *
 * Author: David Woodhouse <dwmw2@infradead.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 */

/*
 * Grateful thanks to Tiebing Zhang, who did much of the hard work
 * of analysing and decoding the protocol.
 */

#include <config.h>

#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdarg.h>
#include <sys/types.h>
#ifndef _WIN32
#include <sys/wait.h>
#endif

#include <libxml/HTMLparser.h>
#include <libxml/HTMLtree.h>

#include "openconnect-internal.h"

/* XX: This is actually a lot of duplication with the CSTP version. */
void oncp_common_headers(struct openconnect_info *vpninfo, struct oc_text_buf *buf)
{
	http_common_headers(vpninfo, buf);

//	buf_append(buf, "Content-Length: 256\r\n");
	buf_append(buf, "NCP-Version: 3\r\n");
//	buf_append(buf, "Accept-Encoding: gzip\r\n");
}


static xmlNodePtr htmlnode_next(xmlNodePtr top, xmlNodePtr node)
{
	if (node->children)
		return node->children;

	while (!node->next) {
		node = node->parent;
		if (!node || node == top)
			return NULL;
	}
	return node->next;
}

static int oncp_can_gen_tokencode(struct openconnect_info *vpninfo,
				  struct oc_auth_form *form,
				  struct oc_form_opt *opt)
{
	if (vpninfo->token_mode == OC_TOKEN_MODE_NONE ||
	    vpninfo->token_bypassed)
		return -EINVAL;

	if (strcmp(form->auth_id, "frmDefender") &&
	    strcmp(form->auth_id, "frmNextToken") &&
	    strcmp(form->auth_id, "frmTotpToken"))
		return -EINVAL;

	return can_gen_tokencode(vpninfo, form, opt);
}


static int parse_input_node(struct openconnect_info *vpninfo, struct oc_auth_form *form,
			    xmlNodePtr node, const char *submit_button)
{
	char *type = (char *)xmlGetProp(node, (unsigned char *)"type");
	struct oc_form_opt **p = &form->opts;
	struct oc_form_opt *opt;
	int ret = 0;

	if (!type)
		return -EINVAL;

	opt = calloc(1, sizeof(*opt));
	if (!opt) {
		ret = -ENOMEM;
		goto out;
	}

	if (!strcasecmp(type, "hidden")) {
		opt->type = OC_FORM_OPT_HIDDEN;
		xmlnode_get_prop(node, "name", &opt->name);
		xmlnode_get_prop(node, "value", &opt->_value);
		/* XXX: Handle tz_offset / tz */
	} else if (!strcasecmp(type, "password")) {
		opt->type = OC_FORM_OPT_PASSWORD;
		xmlnode_get_prop(node, "name", &opt->name);
		if (asprintf(&opt->label, "%s:", opt->name) == -1) {
			ret = -ENOMEM;
			goto out;
		}
		if (!oncp_can_gen_tokencode(vpninfo, form, opt))
			opt->type = OC_FORM_OPT_TOKEN;
	} else if (!strcasecmp(type, "text")) {
		opt->type = OC_FORM_OPT_TEXT;
		xmlnode_get_prop(node, "name", &opt->name);
		if (asprintf(&opt->label, "%s:", opt->name) == -1) {
			ret = -ENOMEM;
			goto out;
		}
	} else if (!strcasecmp(type, "username")) {
		opt->type = OC_FORM_OPT_TEXT;
		xmlnode_get_prop(node, "name", &opt->name);
		if (asprintf(&opt->label, "%s:", opt->name) == -1) {
			ret = -ENOMEM;
			goto out;
		}
	} else if (!strcasecmp(type, "submit")) {
		xmlnode_get_prop(node, "name", &opt->name);
		if (opt->name && (!strcmp(opt->name, submit_button) ||
				  !strcmp(opt->name, "sn-postauth-proceed") ||
				  !strcmp(opt->name, "sn-preauth-proceed"))) {
			/* Use this as the 'Submit' action for the form, by
			   implicitly adding it as a hidden option. */
			xmlnode_get_prop(node, "value", &opt->_value);
			opt->type = OC_FORM_OPT_HIDDEN;
		} else {
			vpn_progress(vpninfo, PRG_DEBUG,
				     _("Ignoring unknown form submit item '%s'\n"),
				     opt->name);
			ret = -EINVAL;
			goto out;
		}
	} else if (!strcasecmp(type, "checkbox")) {
		opt->type = OC_FORM_OPT_HIDDEN;
		xmlnode_get_prop(node, "name", &opt->name);
		xmlnode_get_prop(node, "value", &opt->_value);
	} else {
		vpn_progress(vpninfo, PRG_DEBUG,
			     _("Ignoring unknown form input type '%s'\n"),
			     type);
		ret = -EINVAL;
		goto out;
	}

	/* Append to the existing list */
	while (*p) {
		if (!strcmp((*p)->name, opt->name)) {
			vpn_progress(vpninfo, PRG_DEBUG,
				     _("Discarding duplicate option '%s'\n"),
				     opt->name);
			goto out;
		}
		p = &(*p)->next;
	}
	*p = opt;
 out:
	if (ret)
		free_opt(opt);
	free(type);
	return ret;
}

static int parse_select_node(struct openconnect_info *vpninfo, struct oc_auth_form *form,
		     xmlNodePtr node)
{
	xmlNodePtr child;
	struct oc_form_opt_select *opt;
	struct oc_choice *choice;

	opt = calloc(1, sizeof(*opt));
	if (!opt)
		return -ENOMEM;

	xmlnode_get_prop(node, "name", &opt->form.name);
	opt->form.label = strdup(opt->form.name);
	opt->form.type = OC_FORM_OPT_SELECT;
	if (!strcmp(opt->form.name, "realm"))
		form->authgroup_opt = opt;

	for (child = node->children; child; child = child->next) {
		struct oc_choice **new_choices;
		if (!child->name || strcasecmp((const char *)child->name, "option"))
			continue;

		choice = calloc(1, sizeof(*choice));
		if (!choice)
			return -ENOMEM;

		xmlnode_get_prop(node, "name", &choice->name);
		choice->label = (char *)xmlNodeGetContent(child);
		choice->name = strdup(choice->label);
		new_choices = realloc(opt->choices, sizeof(opt->choices[0]) * (opt->nr_choices+1));
		if (!new_choices) {
			free_opt((void *)opt);
			free(choice);
			return -ENOMEM;
		}
		opt->choices = new_choices;
		opt->choices[opt->nr_choices++] = choice;
	}

	/* Prepend to the existing list */
	opt->form.next = form->opts;
	form->opts = &opt->form;
	return 0;
}

static struct oc_auth_form *parse_form_node(struct openconnect_info *vpninfo,
					    xmlNodePtr node, const char *submit_button)
{
	struct oc_auth_form *form = calloc(1, sizeof(*form));
	xmlNodePtr child;

	if (!form)
		return NULL;

	xmlnode_get_prop(node, "method", &form->method);
	xmlnode_get_prop(node, "action", &form->action);
	if (!form->method || strcasecmp(form->method, "POST") ||
	    !form->action || !form->action[0]) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Cannot handle form method='%s', action='%s'\n"),
			     form->method, form->action);
		free(form);
		return NULL;
	}
	xmlnode_get_prop(node, "name", &form->auth_id);
	form->banner = strdup(form->auth_id);

	for (child = htmlnode_next(node, node); child && child != node; child = htmlnode_next(node, child)) {
		if (!child->name)
			continue;

		if (!strcasecmp((char *)child->name, "input"))
			parse_input_node(vpninfo, form, child, submit_button);
		else if (!strcasecmp((char *)child->name, "select")) {
			parse_select_node(vpninfo, form, child);
			/* Skip its children */
			while (child->children)
				child = child->last;
		} else if (!strcasecmp((char *)child->name, "textarea")) {
			/* display the post sign-in message, if any */
			char *fieldname = (char *)xmlGetProp(child, (unsigned char *)"name");
			if (fieldname && (!strcasecmp(fieldname, "sn-postauth-text") ||
					  !strcasecmp(fieldname, "sn-preauth-text"))) {
				char *postauth_msg = (char *)xmlNodeGetContent(child);
				if (postauth_msg) {
					free(form->banner);
					form->banner = postauth_msg;
				}
			} else {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Unknown textarea field: '%s'\n"), fieldname);
			}
			free(fieldname);
		}
	}
	return form;
}

static xmlNodePtr find_form_node(xmlDocPtr doc)
{
	xmlNodePtr root, node;

	for (root = node = xmlDocGetRootElement(doc); node; node = htmlnode_next(root, node)) {
		if (node->name && !strcasecmp((char *)node->name, "form"))
			return node;
	}
	return NULL;
}

static int check_cookie_success(struct openconnect_info *vpninfo)
{
	const char *dslast = NULL, *dsfirst = NULL, *dsurl = NULL, *dsid = NULL, *dspreauth = NULL;
	struct oc_vpn_option *cookie;
	struct oc_text_buf *buf;

	for (cookie = vpninfo->cookies; cookie; cookie = cookie->next) {
		if (!strcmp(cookie->option, "DSFirstAccess"))
			dsfirst = cookie->value;
		else if (!strcmp(cookie->option, "DSLastAccess"))
			dslast = cookie->value;
		else if (!strcmp(cookie->option, "DSID"))
			dsid = cookie->value;
		else if (!strcmp(cookie->option, "DSSignInUrl"))
			dsurl = cookie->value;
		else if (!strcmp(cookie->option, "DSPREAUTH"))
			dspreauth = cookie->value;
	}
	if (!dsid)
		return -ENOENT;

	buf = buf_alloc();
	if (vpninfo->tncc_fd != -1) {
		buf_append(buf, "setcookie\n");
		buf_append(buf, "Cookie=%s\n", dspreauth);
		if (buf_error(buf))
			return buf_free(buf);
		send(vpninfo->tncc_fd, buf->data, buf->pos, 0);
		buf_truncate(buf);
	}

	/* XXX: Do these need escaping? Could they theoreetically have semicolons in? */
	buf_append(buf, "DSID=%s", dsid);
	if (dsfirst)
		buf_append(buf, "; DSFirst=%s", dsfirst);
	if (dslast)
		buf_append(buf, "; DSLast=%s", dslast);
	if (dsurl)
		buf_append(buf, "; DSSignInUrl=%s", dsurl);
	if (buf_error(buf))
		return buf_free(buf);
	free(vpninfo->cookie);
	vpninfo->cookie = buf->data;
	buf->data = NULL;
	buf_free(buf);
	return 0;
}
#ifdef _WIN32
static int tncc_preauth(struct openconnect_info *vpninfo)
{
	vpn_progress(vpninfo, PRG_ERR,
		     _("TNCC support not implemented yet on Windows\n"));
	return -EOPNOTSUPP;
}
#else
static int tncc_preauth(struct openconnect_info *vpninfo)
{
	int sockfd[2];
	pid_t pid;
	struct oc_text_buf *buf;
	struct oc_vpn_option *cookie;
	const char *dspreauth = NULL, *dssignin = "null";
	char recvbuf[1024];
	int len;

	for (cookie = vpninfo->cookies; cookie; cookie = cookie->next) {
		if (!strcmp(cookie->option, "DSPREAUTH"))
			dspreauth = cookie->value;
		else if (!strcmp(cookie->option, "DSSIGNIN"))
			dssignin = cookie->value;
	}
	if (!dspreauth) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("No DSPREAUTH cookie; not attempting TNCC\n"));
		return -EINVAL;
	}

#ifdef SOCK_CLOEXEC
	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, sockfd))
#endif
	{
		if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockfd))
			return -errno;

		set_fd_cloexec(sockfd[0]);
		set_fd_cloexec(sockfd[1]);
	}
	pid = fork();
	if (pid == -1) {
		close(sockfd[0]);
		close(sockfd[1]);
		return -errno;
	}

	if (!pid) {
		int i;
		/* Fork again to detach grandchild */
		if (fork())
			exit(1);

		close(sockfd[1]);
		/* The duplicated fd does not have O_CLOEXEC */
		dup2(sockfd[0], 0);
		/* We really don't want anything going to our stdout.
		   Redirect the child's stdout, to our stderr. */
		dup2(2, 1);
		/* And close everything else.*/
		for (i = 3; i < 1024 ; i++)
			close(i);

		execl(vpninfo->csd_wrapper, vpninfo->csd_wrapper, vpninfo->hostname, NULL);
		fprintf(stderr, _("Failed to exec TNCC script %s: %s\n"),
			vpninfo->csd_wrapper, strerror(errno));
		exit(1);
	}
	waitpid(pid, NULL, 0);
	close(sockfd[0]);

	buf = buf_alloc();
	buf_append(buf, "start\n");
	buf_append(buf, "IC=%s\n", vpninfo->hostname);
	buf_append(buf, "Cookie=%s\n", dspreauth);
	buf_append(buf, "DSSIGNIN=%s\n", dssignin);
	if (buf_error(buf)) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Failed to allocate memory for communication with TNCC\n"));
		close(sockfd[1]);
		return buf_free(buf);
	}

	if (cancellable_send(vpninfo, sockfd[1], buf->data, buf->pos) != buf->pos) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Failed to send start command to TNCC\n"));
		buf_free(buf);
		close(sockfd[1]);
		return -EIO;
	}
	buf_free(buf);
	vpn_progress(vpninfo, PRG_DEBUG,
		     _("Sent start; waiting for response from TNCC\n"));

	/* First line: HTTP-like response code. */
	len = cancellable_gets(vpninfo, sockfd[1], recvbuf, sizeof(recvbuf));
	if (len < 0) {
	respfail:
		vpn_progress(vpninfo, PRG_ERR,
			     _("Failed to read response from TNCC\n"));
		close(sockfd[1]);
		return -EIO;
	}

	if (strcmp(recvbuf, "200")) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Received unsuccessful %s response from TNCC\n"),
			     recvbuf);
		close(sockfd[1]);
		return -EINVAL;
	}

	vpn_progress(vpninfo, PRG_TRACE, _("TNCC response 200 OK\n"));

	/* We're not sure what the second line is. We ignore it. */
	len = cancellable_gets(vpninfo, sockfd[1], recvbuf, sizeof(recvbuf));
	if (len < 0)
		goto respfail;

	vpn_progress(vpninfo, PRG_TRACE, _("Second line of TNCC response: '%s'\n"),
		     recvbuf);

	/* Third line is the DSPREAUTH cookie */
	len = cancellable_gets(vpninfo, sockfd[1], recvbuf, sizeof(recvbuf));
	if (len < 0)
		goto respfail;

	vpn_progress(vpninfo, PRG_DEBUG,
		     _("Got new DSPREAUTH cookie from TNCC: %s\n"),
		     recvbuf);
	http_add_cookie(vpninfo, "DSPREAUTH", recvbuf, 1);
	vpninfo->tncc_fd = sockfd[1];

	len = cancellable_gets(vpninfo, sockfd[1], recvbuf, sizeof(recvbuf));
	if (len < 0)
		goto respfail;
	if (len > 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected non-empty line from TNCC after DSPREAUTH cookie: '%s'\n"),
			     recvbuf);
		goto respfail;
	}

	return 0;
}
#endif

static struct oc_auth_form *parse_roles_table_node(xmlNodePtr node)
{
	struct oc_auth_form *form;
	xmlNodePtr table_itr;
	xmlNodePtr row_itr;
	xmlNodePtr data_itr;
	struct oc_form_opt_select *opt;
	struct oc_choice *choice;

	form = calloc(1, sizeof(*form));
	if (!form)
		return NULL;

	opt = calloc(1, sizeof(*opt));
	if (!opt) {
		free(form);
		return NULL;
	}

	form->opts = &opt->form;
	opt->form.label = strdup("frmSelectRoles");
	opt->form.name = strdup("frmSelectRoles");
	opt->form.type = OC_FORM_OPT_SELECT;

	for (table_itr = node->children; table_itr; table_itr = table_itr->next) {
		if (!table_itr->name || strcasecmp((const char *)table_itr->name, "tr"))
			continue;
		for (row_itr = table_itr->children; row_itr; row_itr = row_itr->next) {
			if (!row_itr->name || strcasecmp((const char *)row_itr->name, "td"))
				continue;
			for (data_itr = row_itr->children; data_itr; data_itr = data_itr->next) {
				struct oc_choice **new_choices;
				char *role_link = NULL;
				char *role_name = NULL;

				if (!data_itr->name || strcasecmp((const char *)data_itr->name, "a"))
					continue;

				// Discovered <a> tag with role selection.
				role_link = (char *)xmlGetProp(data_itr, (unsigned char *)"href");
				if (!role_link)
					continue;

				role_name = (char *)xmlNodeGetContent(data_itr);
				if (!role_name) {
					// some weird case?
					free(role_link);
					continue;
				}

				choice = calloc(1, sizeof(*choice));
				if (!choice) {
					free(role_name);
					free(role_link);
					free_auth_form(form);
					return NULL;
				}

				choice->label = role_name;
				choice->name = role_link;
				new_choices = realloc(opt->choices, sizeof(opt->choices[0]) * (opt->nr_choices+1));
				if (!new_choices) {
					free(choice);
					free(role_name);
					free(role_link);
					free_auth_form(form);
					return NULL;
				}
				opt->choices = new_choices;
				opt->choices[opt->nr_choices++] = choice;
			}
		}
	}

	return form;
}

static struct oc_auth_form *parse_roles_form_node(xmlNodePtr node)
{
	struct oc_auth_form *form = NULL;
	xmlNodePtr child;

	// Set form->action here as a redirect url with keys and ids.
	for (child = htmlnode_next(node, node); child && child != node;
	     child = htmlnode_next(node, child)) {
		if (child->name && !strcasecmp((char *)child->name, "table")) {
			char *table_id = (char *)xmlGetProp(child, (unsigned char *)"id");

			if (table_id) {
				if (!strcmp(table_id, "TABLE_SelectRole_1"))
					form = parse_roles_table_node(child);

				free(table_id);

				if (form)
					break;
			}
		}
	}

	return form;
}

int oncp_obtain_cookie(struct openconnect_info *vpninfo)
{
	int ret;
	struct oc_text_buf *resp_buf = NULL;
	xmlDocPtr doc = NULL;
	xmlNodePtr node;
	struct oc_auth_form *form = NULL;
	char *form_id = NULL;
	int try_tncc = !!vpninfo->csd_wrapper;

	resp_buf = buf_alloc();
	if (buf_error(resp_buf))
		return -ENOMEM;

	while (1) {
		char *form_buf = NULL;
		int role_select = 0;
		struct oc_text_buf *url;

		if (resp_buf && resp_buf->pos)
			ret = do_https_request(vpninfo, "POST",
					       "application/x-www-form-urlencoded",
					       resp_buf, &form_buf, 2);
		else
			ret = do_https_request(vpninfo, "GET", NULL, NULL,
					       &form_buf, 2);

		if (ret < 0)
			break;

		url = buf_alloc();
		buf_append(url, "https://%s", vpninfo->hostname);
		if (vpninfo->port != 443)
			buf_append(url, ":%d", vpninfo->port);
		buf_append(url, "/");
		if (vpninfo->urlpath)
			buf_append(url, "%s", vpninfo->urlpath);

		if (buf_error(url)) {
			free(form_buf);
			ret = buf_free(url);
			break;
		}

		if (!check_cookie_success(vpninfo)) {
			buf_free(url);
			free(form_buf);
			ret = 0;
			break;
		}

		doc = htmlReadMemory(form_buf, ret, url->data, NULL,
				     HTML_PARSE_RECOVER|HTML_PARSE_NOERROR|HTML_PARSE_NOWARNING|HTML_PARSE_NONET);
		buf_free(url);
		free(form_buf);
		if (!doc) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Failed to parse HTML document\n"));
			ret = -EINVAL;
			break;
		}

		buf_truncate(resp_buf);

		node = find_form_node(doc);
		if (!node) {
			if (try_tncc) {
				try_tncc = 0;
				ret = tncc_preauth(vpninfo);
				if (ret)
					return ret;
				goto tncc_done;
			}
			vpn_progress(vpninfo, PRG_ERR,
				     _("Failed to find or parse web form in login page\n"));
			ret = -EINVAL;
			break;
		}
		free(form_id);
		form_id = (char *)xmlGetProp(node, (unsigned char *)"name");
		if (!form_id) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Encountered form with no ID\n"));
			goto dump_form;
		} else if (!strcmp(form_id, "frmLogin")) {
			form = parse_form_node(vpninfo, node, "btnSubmit");
			if (!form) {
				ret = -EINVAL;
				break;
			}
		} else if (!strcmp(form_id, "frmDefender") ||
			   !strcmp(form_id, "frmNextToken")) {
			form = parse_form_node(vpninfo, node, "btnAction");
			if (!form) {
				ret = -EINVAL;
				break;
			}
		} else if (!strcmp(form_id, "frmConfirmation")) {
			form = parse_form_node(vpninfo, node, "btnContinue");
			if (!form) {
				ret = -EINVAL;
				break;
			}
			/* XXX: Actually ask the user? */
			goto form_done;
		} else if (!strcmp(form_id, "frmSelectRoles")) {
			form = parse_roles_form_node(node);
			if (!form) {
				ret = -EINVAL;
				break;
			}
			role_select = 1;
		} else if (!strcmp(form_id, "frmTotpToken")) {
			form = parse_form_node(vpninfo, node, "totpactionEnter");
			if (!form) {
				ret = -EINVAL;
				break;
			}
		} else {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Unknown form ID '%s'\n"),
				     form_id);
		dump_form:
			fprintf(stderr, _("Dumping unknown HTML form:\n"));
			htmlNodeDumpFileFormat(stderr, node->doc, node, NULL, 1);
			ret = -EINVAL;
			break;
		}

		do {
			ret = process_auth_form(vpninfo, form);
		} while (ret == OC_FORM_RESULT_NEWGROUP);
		if (ret)
			goto out;

		ret = do_gen_tokencode(vpninfo, form);
		if (ret) {
			vpn_progress(vpninfo, PRG_ERR, _("Failed to generate OTP tokencode; disabling token\n"));
			vpninfo->token_bypassed = 1;
			goto out;
		}

		/* frmSelectRoles is special; it's actually *links*, not a form. So
		 * we need to process it differently... */
		if (role_select) {
			vpninfo->redirect_url = strdup(form->opts[0]._value);
			goto do_redirect;
		}
	form_done:
		append_form_opts(vpninfo, form, resp_buf);
		ret = buf_error(resp_buf);
		if (ret)
			break;

		vpninfo->redirect_url = form->action;
		form->action = NULL;
	do_redirect:
		free_auth_form(form);
		form = NULL;
		handle_redirect(vpninfo);

	tncc_done:
		xmlFreeDoc(doc);
		doc = NULL;
	}
 out:
	if (doc)
		xmlFreeDoc(doc);
	free(form_id);
	if (form)
		free_auth_form(form);
	buf_free(resp_buf);
	return ret;
}