/*
 * OpenConnect (SSL + DTLS) VPN client
 *
 * Copyright © 2008-2015 Intel Corporation.
 * Copyright © 2008 Nick Andrew <nick@nick-andrew.net>
 *
 * 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.
 */

#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 <stdarg.h>

#include "openconnect-internal.h"

static int proxy_write(struct openconnect_info *vpninfo, char *buf, size_t len);
static int proxy_read(struct openconnect_info *vpninfo, char *buf, size_t len);

#define MAX_BUF_LEN 131072
#define BUF_CHUNK_SIZE 4096

struct oc_text_buf *buf_alloc(void)
{
	return calloc(1, sizeof(struct oc_text_buf));
}

void buf_append_urlencoded(struct oc_text_buf *buf, const char *str)
{
	while (str && *str) {
		unsigned char c = *str;
		if (c < 0x80 && (isalnum((int)(c)) || c=='-' || c=='_' || c=='.' || c=='~'))
			buf_append_bytes(buf, str, 1);
		else
			buf_append(buf, "%%%02x", c);

		str++;
	}
}

void buf_append_hex(struct oc_text_buf *buf, const void *str, unsigned len)
{
	const unsigned char *data = str;
	unsigned i;

	for (i = 0; i < len; i++)
		buf_append(buf, "%02x", (unsigned)data[i]);
}

void buf_truncate(struct oc_text_buf *buf)
{
	if (!buf)
		return;

	buf->pos = 0;
	if (buf->data)
		buf->data[0] = 0;
}

int buf_ensure_space(struct oc_text_buf *buf, int len)
{
	int new_buf_len;

	new_buf_len = (buf->pos + len + BUF_CHUNK_SIZE - 1) & ~(BUF_CHUNK_SIZE - 1);

	if (new_buf_len <= buf->buf_len)
		return 0;

	if (new_buf_len > MAX_BUF_LEN) {
		buf->error = -E2BIG;
		return buf->error;
	} else {
		realloc_inplace(buf->data, new_buf_len);
		if (!buf->data)
			buf->error = -ENOMEM;
		else
			buf->buf_len = new_buf_len;
	}
	return buf->error;
}

void  __attribute__ ((format (printf, 2, 3)))
	buf_append(struct oc_text_buf *buf, const char *fmt, ...)
{
	va_list ap;

	if (!buf || buf->error)
		return;

	if (buf_ensure_space(buf, 1))
		return;

	while (1) {
		int max_len = buf->buf_len - buf->pos, ret;

		va_start(ap, fmt);
		ret = vsnprintf(buf->data + buf->pos, max_len, fmt, ap);
		va_end(ap);
		if (ret < 0) {
			buf->error = -EIO;
			break;
		} else if (ret < max_len) {
			buf->pos += ret;
			break;
		} else if (buf_ensure_space(buf, ret))
			break;
	}
}

void buf_append_bytes(struct oc_text_buf *buf, const void *bytes, int len)
{
	if (!buf || buf->error)
		return;

	if (buf_ensure_space(buf, len + 1))
		return;

	memcpy(buf->data + buf->pos, bytes, len);
	buf->pos += len;
	buf->data[buf->pos] = 0;
}

void buf_append_from_utf16le(struct oc_text_buf *buf, const void *_utf16)
{
	const unsigned char *utf16 = _utf16;
	unsigned char utf8[4];
	int c;

	if (!utf16)
		return;

	while (utf16[0] || utf16[1]) {
		if ((utf16[1] & 0xfc) == 0xd8 && (utf16[3] & 0xfc) == 0xdc) {
			c = ((load_le16(utf16) & 0x3ff) << 10)|
				(load_le16(utf16 + 2) & 0x3ff);
			c += 0x10000;
			utf16 += 4;
		} else {
			c = load_le16(utf16);
			utf16 += 2;
		}

		if (c < 0x80) {
			utf8[0] = c;
			buf_append_bytes(buf, utf8, 1);
		} else if (c < 0x800) {
			utf8[0] = 0xc0 | (c >> 6);
			utf8[1] = 0x80 | (c & 0x3f);
			buf_append_bytes(buf, utf8, 2);
		} else if (c < 0x10000) {
			utf8[0] = 0xe0 | (c >> 12);
			utf8[1] = 0x80 | ((c >> 6) & 0x3f);
			utf8[2] = 0x80 | (c & 0x3f);
			buf_append_bytes(buf, utf8, 3);
		} else {
			utf8[0] = 0xf0 | (c >> 18);
			utf8[1] = 0x80 | ((c >> 12) & 0x3f);
			utf8[2] = 0x80 | ((c >> 6) & 0x3f);
			utf8[3] = 0x80 | (c & 0x3f);
			buf_append_bytes(buf, utf8, 4);
		}
	}
	utf8[0] = 0;
	buf_append_bytes(buf, utf8, 1);
}

int get_utf8char(const char **p)
{
	const char *utf8 = *p;
	unsigned char c;
	int utfchar, nr_extra, min;

	c = *(utf8++);
	if (c < 128) {
		utfchar = c;
		nr_extra = 0;
		min = 0;
	} else if ((c & 0xe0) == 0xc0) {
		utfchar = c & 0x1f;
		nr_extra = 1;
		min = 0x80;
	} else if ((c & 0xf0) == 0xe0) {
		utfchar = c & 0x0f;
		nr_extra = 2;
		min = 0x800;
	} else if ((c & 0xf8) == 0xf0) {
		utfchar = c & 0x07;
		nr_extra = 3;
		min = 0x10000;
	} else {
		return -EILSEQ;
	}

	while (nr_extra--) {
		c = *(utf8++);
		if ((c & 0xc0) != 0x80)
			return -EILSEQ;

		utfchar <<= 6;
		utfchar |= (c & 0x3f);
	}
	if (utfchar > 0x10ffff || utfchar < min)
		return -EILSEQ;

	*p = utf8;
	return utfchar;
}

int buf_append_utf16le(struct oc_text_buf *buf, const char *utf8)
{
	int utfchar, len = 0;

	/* Ick. Now I'm implementing my own UTF8 handling too. Perhaps it's
	   time to bite the bullet and start requiring something like glib? */
	while (*utf8) {
		utfchar = get_utf8char(&utf8);
		if (utfchar < 0) {
			if (buf)
				buf->error = utfchar;
			return utfchar;
		}
		if (!buf)
			continue;

		if (utfchar >= 0x10000) {
			utfchar -= 0x10000;
			if (buf_ensure_space(buf, 4))
				return buf_error(buf);
			store_le16(buf->data + buf->pos, (utfchar >> 10) | 0xd800);
			store_le16(buf->data + buf->pos + 2, (utfchar & 0x3ff) | 0xdc00);
			buf->pos += 4;
			len += 4;
		} else {
			if (buf_ensure_space(buf, 2))
				return buf_error(buf);
			store_le16(buf->data + buf->pos, utfchar);
			buf->pos += 2;
			len += 2;
		}
	}

	/* We were only being used for validation */
	if (!buf)
		return 0;

	/* Ensure UTF16 is NUL-terminated */
	if (buf_ensure_space(buf, 2))
		return buf_error(buf);
	buf->data[buf->pos] = buf->data[buf->pos + 1] = 0;

	return len;
}

int buf_error(struct oc_text_buf *buf)
{
	return buf ? buf->error : -ENOMEM;
}

int buf_free(struct oc_text_buf *buf)
{
	int error = buf_error(buf);

	if (buf) {
		if (buf->data)
			free(buf->data);
		free(buf);
	}

	return error;
}

/*
 * We didn't really want to have to do this for ourselves -- one might have
 * thought that it would be available in a library somewhere. But neither
 * cURL nor Neon have reliable cross-platform ways of either using a cert
 * from the TPM, or just reading from / writing to a transport which is
 * provided by their caller.
 */

int http_add_cookie(struct openconnect_info *vpninfo, const char *option,
		    const char *value, int replace)
{
	struct oc_vpn_option *new, **this;

	if (*value) {
		new = malloc(sizeof(*new));
		if (!new) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("No memory for allocating cookies\n"));
			return -ENOMEM;
		}
		new->next = NULL;
		new->option = strdup(option);
		new->value = strdup(value);
		if (!new->option || !new->value) {
			free(new->option);
			free(new->value);
			free(new);
			return -ENOMEM;
		}
	} else {
		/* Kill cookie; don't replace it */
		new = NULL;
		/* This would be meaningless */
		if (!replace)
			return -EINVAL;
	}
	for (this = &vpninfo->cookies; *this; this = &(*this)->next) {
		if (!strcmp(option, (*this)->option)) {
			if (!replace) {
				free(new->value);
				free(new->option);
				free(new);
				return 0;
			}
			/* Replace existing cookie */
			if (new)
				new->next = (*this)->next;
			else
				new = (*this)->next;

			free((*this)->option);
			free((*this)->value);
			free(*this);
			*this = new;
			break;
		}
	}
	if (new && !*this) {
		*this = new;
		new->next = NULL;
	}
	return 0;
}

#define BODY_HTTP10 -1
#define BODY_CHUNKED -2

int process_http_response(struct openconnect_info *vpninfo, int connect,
			  int (*header_cb)(struct openconnect_info *, char *, char *),
			  struct oc_text_buf *body)
{
	char buf[MAX_BUF_LEN];
	int bodylen = BODY_HTTP10;
	int closeconn = 0;
	int result;
	int i;

	buf_truncate(body);

 cont:
	if (vpninfo->ssl_gets(vpninfo, buf, sizeof(buf)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error fetching HTTPS response\n"));
		openconnect_close_https(vpninfo, 0);
		return -EINVAL;
	}

	if (!strncmp(buf, "HTTP/1.0 ", 9))
		closeconn = 1;

	if ((!closeconn && strncmp(buf, "HTTP/1.1 ", 9)) || !(result = atoi(buf+9))) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Failed to parse HTTP response '%s'\n"), buf);
		openconnect_close_https(vpninfo, 0);
		return -EINVAL;
	}

	vpn_progress(vpninfo, (result == 200 || result == 407) ? PRG_DEBUG : PRG_INFO,
		     _("Got HTTP response: %s\n"), buf);

	/* Eat headers... */
	while ((i = vpninfo->ssl_gets(vpninfo, buf, sizeof(buf)))) {
		char *colon;

		if (i < 0) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Error processing HTTP response\n"));
			openconnect_close_https(vpninfo, 0);
			return -EINVAL;
		}
		colon = strchr(buf, ':');
		if (!colon) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Ignoring unknown HTTP response line '%s'\n"), buf);
			continue;
		}
		*(colon++) = 0;
		if (*colon == ' ')
			colon++;

		/* Handle Set-Cookie first so that we can avoid printing the
		   webvpn cookie in the verbose debug output */
		if (!strcasecmp(buf, "Set-Cookie")) {
			char *semicolon = strchr(colon, ';');
			const char *print_equals;
			char *equals = strchr(colon, '=');
			int ret;

			if (semicolon)
				*semicolon = 0;

			if (!equals) {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Invalid cookie offered: %s\n"), buf);
				return -EINVAL;
			}
			*(equals++) = 0;

			print_equals = equals;
			/* Don't print the webvpn cookie unless it's empty; we don't
			   want people posting it in public with debugging output */
			if (!strcmp(colon, "webvpn") && *equals)
				print_equals = _("<elided>");
			vpn_progress(vpninfo, PRG_DEBUG, "%s: %s=%s%s%s\n",
				     buf, colon, print_equals, semicolon ? ";" : "",
				     semicolon ? (semicolon+1) : "");

			/* The server tends to ask for the username and password as
			   usual, even if we've already failed because it didn't like
			   our cert. Thankfully it does give us this hint... */
			if (!strcmp(colon, "ClientCertAuthFailed"))
				vpn_progress(vpninfo, PRG_ERR,
					     _("SSL certificate authentication failed\n"));

			ret = http_add_cookie(vpninfo, colon, equals, 1);
			if (ret)
				return ret;
		} else {
			vpn_progress(vpninfo, PRG_DEBUG, "%s: %s\n", buf, colon);
		}

		if (!strcasecmp(buf, "Connection")) {
			if (!strcasecmp(colon, "Close"))
				closeconn = 1;
#if 0
			/* This might seem reasonable, but in fact it breaks
			   certificate authentication with some servers. If
			   they give an HTTP/1.0 response, even if they
			   explicitly give a Connection: Keep-Alive header,
			   just close the connection. */
			else if (!strcasecmp(colon, "Keep-Alive"))
				closeconn = 0;
#endif
		}
		if (!strcasecmp(buf, "Location")) {
			vpninfo->redirect_url = strdup(colon);
			if (!vpninfo->redirect_url)
				return -ENOMEM;
		}
		if (!strcasecmp(buf, "Content-Length")) {
			bodylen = atoi(colon);
			if (bodylen < 0) {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Response body has negative size (%d)\n"),
					     bodylen);
				openconnect_close_https(vpninfo, 0);
				return -EINVAL;
			}
		}
		if (!strcasecmp(buf, "Transfer-Encoding")) {
			if (!strcasecmp(colon, "chunked"))
				bodylen = BODY_CHUNKED;
			else {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Unknown Transfer-Encoding: %s\n"),
					     colon);
				openconnect_close_https(vpninfo, 0);
				return -EINVAL;
			}
		}
		if (header_cb)
			header_cb(vpninfo, buf, colon);
	}

	/* Handle 'HTTP/1.1 100 Continue'. Not that we should ever see it */
	if (result == 100)
		goto cont;

	/* On successful CONNECT, there is no body. Return success */
	if (connect && result == 200)
		return result;

	/* Now the body, if there is one */
	vpn_progress(vpninfo, PRG_DEBUG, _("HTTP body %s (%d)\n"),
		     bodylen == BODY_HTTP10 ? "http 1.0" :
		     bodylen == BODY_CHUNKED ? "chunked" : "length: ",
		     bodylen);

	/* If we were given Content-Length, it's nice and easy... */
	if (bodylen > 0) {
		if (buf_ensure_space(body, bodylen + 1))
			return buf_error(body);

		while (body->pos < bodylen) {
			i = vpninfo->ssl_read(vpninfo, body->data + body->pos, bodylen - body->pos);
			if (i < 0) {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Error reading HTTP response body\n"));
				openconnect_close_https(vpninfo, 0);
				return -EINVAL;
			}
			body->pos += i;
		}
	} else if (bodylen == BODY_CHUNKED) {
		/* ... else, chunked */
		while ((i = vpninfo->ssl_gets(vpninfo, buf, sizeof(buf)))) {
			int chunklen, lastchunk = 0;

			if (i < 0) {
				vpn_progress(vpninfo, PRG_ERR,
					     _("Error fetching chunk header\n"));
				return i;
			}
			chunklen = strtol(buf, NULL, 16);
			if (!chunklen) {
				lastchunk = 1;
				goto skip;
			}
			if (buf_ensure_space(body, chunklen + 1))
				return buf_error(body);
			while (chunklen) {
				i = vpninfo->ssl_read(vpninfo, body->data + body->pos, chunklen);
				if (i < 0) {
					vpn_progress(vpninfo, PRG_ERR,
						     _("Error reading HTTP response body\n"));
					return -EINVAL;
				}
				chunklen -= i;
				body->pos += i;
			}
		skip:
			if ((i = vpninfo->ssl_gets(vpninfo, buf, sizeof(buf)))) {
				if (i < 0) {
					vpn_progress(vpninfo, PRG_ERR,
						     _("Error fetching HTTP response body\n"));
				} else {
					vpn_progress(vpninfo, PRG_ERR,
						     _("Error in chunked decoding. Expected '', got: '%s'"),
						     buf);
				}
				return -EINVAL;
			}

			if (lastchunk)
				break;
		}
	} else if (bodylen == BODY_HTTP10) {
		if (!closeconn) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Cannot receive HTTP 1.0 body without closing connection\n"));
			openconnect_close_https(vpninfo, 0);
			return -EINVAL;
		}

		/* HTTP 1.0 response. Just eat all we can in 4KiB chunks */
		while (1) {
			if (buf_ensure_space(body, 4096 + 1))
				return buf_error(body);
			i = vpninfo->ssl_read(vpninfo, body->data + body->pos, 4096);
			if (i < 0) {
				/* Error */
				openconnect_close_https(vpninfo, 0);
				return i;
			} else if (!i)
				break;

			/* Got more data */
			body->pos += i;
		}
	}

	if (closeconn || vpninfo->no_http_keepalive)
		openconnect_close_https(vpninfo, 0);

	body->data[body->pos] = 0;
	return result;
}

int internal_parse_url(const char *url, char **res_proto, char **res_host,
		       int *res_port, char **res_path, int default_port)
{
	const char *orig_host, *orig_path;
	char *host, *port_str;
	int port, proto_len = 0;

	orig_host = strstr(url, "://");
	if (orig_host) {
		proto_len = orig_host - url;
		orig_host += 3;

		if (strprefix_match(url, proto_len, "https"))
			port = 443;
		else if (strprefix_match(url, proto_len, "http"))
			port = 80;
		else if (strprefix_match(url, proto_len, "socks") ||
			 strprefix_match(url, proto_len, "socks4") ||
			 strprefix_match(url, proto_len, "socks5"))
			port = 1080;
		else
			return -EPROTONOSUPPORT;
	} else {
		if (default_port) {
			port = default_port;
			orig_host = url;
		} else
			return -EINVAL;
	}

	orig_path = strchr(orig_host, '/');
	if (orig_path) {
		host = strndup(orig_host, orig_path - orig_host);
		orig_path++;
	} else
		host = strdup(orig_host);
	if (!host)
		return -ENOMEM;

	port_str = strrchr(host, ':');
	if (port_str) {
		char *end;
		int new_port = strtol(port_str + 1, &end, 10);

		if (!*end) {
			*port_str = 0;
			port = new_port;
		}
	}

	if (res_proto)
		*res_proto = proto_len ? strndup(url, proto_len) : NULL;
	if (res_host)
		*res_host = host;
	else
		free(host);
	if (res_port)
		*res_port = port;
	if (res_path)
		*res_path = (orig_path && *orig_path) ? strdup(orig_path) : NULL;

	return 0;
}

void openconnect_clear_cookies(struct openconnect_info *vpninfo)
{
	struct oc_vpn_option *opt, *next;

	for (opt = vpninfo->cookies; opt; opt = next) {
		next = opt->next;

		free(opt->option);
		free(opt->value);
		free(opt);
	}
	vpninfo->cookies = NULL;
}

/* Return value:
 *  < 0, on error
 *  = 0, on success (go ahead and retry with the latest vpninfo->{hostname,urlpath,port,...})
 */
int handle_redirect(struct openconnect_info *vpninfo)
{
	vpninfo->redirect_type = REDIR_TYPE_LOCAL;

	if (!strncmp(vpninfo->redirect_url, "https://", 8)) {
		/* New host. Tear down the existing connection and make a new one */
		char *host;
		int port;
		int ret;

		free(vpninfo->urlpath);
		vpninfo->urlpath = NULL;

		ret = internal_parse_url(vpninfo->redirect_url, NULL, &host, &port, &vpninfo->urlpath, 0);
		if (ret) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Failed to parse redirected URL '%s': %s\n"),
				     vpninfo->redirect_url, strerror(-ret));
			free(vpninfo->redirect_url);
			vpninfo->redirect_url = NULL;
			return ret;
		}

		if (strcasecmp(vpninfo->hostname, host) || port != vpninfo->port) {
			openconnect_set_hostname(vpninfo, host);
			vpninfo->port = port;

			/* Kill the existing connection, and a new one will happen */
			openconnect_close_https(vpninfo, 0);
			openconnect_clear_cookies(vpninfo);
			vpninfo->redirect_type = REDIR_TYPE_NEWHOST;
		}
		free(host);

		free(vpninfo->redirect_url);
		vpninfo->redirect_url = NULL;

		return 0;
	} else if (strstr(vpninfo->redirect_url, "://")) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Cannot follow redirection to non-https URL '%s'\n"),
			     vpninfo->redirect_url);
		free(vpninfo->redirect_url);
		vpninfo->redirect_url = NULL;
		return -EINVAL;
	} else if (vpninfo->redirect_url[0] == '/') {
		/* Absolute redirect within same host */
		free(vpninfo->urlpath);
		vpninfo->urlpath = strdup(vpninfo->redirect_url + 1);
		free(vpninfo->redirect_url);
		vpninfo->redirect_url = NULL;
		return 0;
	} else {
		char *lastslash = NULL;
		if (vpninfo->urlpath)
			lastslash = strrchr(vpninfo->urlpath, '/');
		if (!lastslash) {
			free(vpninfo->urlpath);
			vpninfo->urlpath = vpninfo->redirect_url;
			vpninfo->redirect_url = NULL;
		} else {
			char *oldurl = vpninfo->urlpath;
			*lastslash = 0;
			vpninfo->urlpath = NULL;
			if (asprintf(&vpninfo->urlpath, "%s/%s",
				     oldurl, vpninfo->redirect_url) == -1) {
				int err = -errno;
				vpn_progress(vpninfo, PRG_ERR,
					     _("Allocating new path for relative redirect failed: %s\n"),
					     strerror(-err));
				return err;
			}
			free(oldurl);
			free(vpninfo->redirect_url);
			vpninfo->redirect_url = NULL;
		}
		return 0;
	}
}

void dump_buf(struct openconnect_info *vpninfo, char prefix, char *buf)
{
	while (*buf) {
		char *eol = buf;
		char eol_char = 0;

		while (*eol) {
			if (*eol == '\r' || *eol == '\n') {
				eol_char = *eol;
				*eol = 0;
				break;
			}
			eol++;
		}

		vpn_progress(vpninfo, PRG_DEBUG, "%c %s\n", prefix, buf);
		if (!eol_char)
			break;

		*eol = eol_char;
		buf = eol + 1;
		if (eol_char == '\r' && *buf == '\n')
			buf++;
	}
}

/* Inputs:
 *  method:             GET or POST
 *  vpninfo->hostname:  Host DNS name
 *  vpninfo->port:      TCP port, typically 443
 *  vpninfo->urlpath:   Relative path, e.g. /+webvpn+/foo.html
 *  request_body_type:  Content type for a POST (e.g. text/html).  Can be NULL.
 *  request_body:       POST content
 *  form_buf:           Callee-allocated buffer for server content
 *
 * Return value:
 *  < 0, on error
 *  >=0, on success, indicating the length of the data in *form_buf
 */
int do_https_request(struct openconnect_info *vpninfo, const char *method,
		     const char *request_body_type, struct oc_text_buf *request_body,
		     char **form_buf, int fetch_redirect)
{
	struct oc_text_buf *buf = buf_alloc();
	int result;
	int rq_retry;
	int rlen, pad;
	int auth = 0;
	int max_redirects = 10;

	if (request_body_type && buf_error(request_body))
		return buf_error(request_body);

 redirected:
	if (max_redirects-- <= 0) {
		result = -EIO;
		goto out;
	}

	vpninfo->redirect_type = REDIR_TYPE_NONE;

	if (*form_buf) {
		free(*form_buf);
		*form_buf = NULL;
	}

	/*
	 * A long time ago, I *wanted* to use an HTTP client library like cURL
	 * for this. But we need a *lot* of control over the underlying SSL
	 * transport, and we also have to do horrid tricks like the Juniper NC
	 * 'GET' request that actaully behaves like a 'CONNECT'.
	 *
	 * So the world gained Yet Another HTTP Implementation. Sorry.
	 *
	 */
	buf_truncate(buf);
	buf_append(buf, "%s /%s HTTP/1.1\r\n", method, vpninfo->urlpath ?: "");
	if (auth) {
		result = gen_authorization_hdr(vpninfo, 0, buf);
		if (result)
			goto out;

		/* Forget existing challenges */
		clear_auth_states(vpninfo, vpninfo->http_auth, 0);
	}
	if (vpninfo->proto->add_http_headers)
		vpninfo->proto->add_http_headers(vpninfo, buf);

	if (request_body_type) {
		rlen = request_body->pos;

		/* force body length to be a multiple of 64, to avoid leaking
		 * password length. */
		pad = 64*(1+rlen/64) - rlen;
		buf_append(buf, "X-Pad: %0*d\r\n", pad, 0);

		buf_append(buf, "Content-Type: %s\r\n", request_body_type);
		buf_append(buf, "Content-Length: %d\r\n", (int)rlen);
	}
	buf_append(buf, "\r\n");

	if (request_body_type)
		buf_append_bytes(buf, request_body->data, request_body->pos);

	if (vpninfo->port == 443)
		vpn_progress(vpninfo, PRG_INFO, "%s https://%s/%s\n",
			     method, vpninfo->hostname,
			     vpninfo->urlpath ?: "");
	else
		vpn_progress(vpninfo, PRG_INFO, "%s https://%s:%d/%s\n",
			     method, vpninfo->hostname, vpninfo->port,
			     vpninfo->urlpath ?: "");

	if (buf_error(buf))
		return buf_free(buf);

	vpninfo->retry_on_auth_fail = 0;

 retry:
	if (openconnect_https_connected(vpninfo)) {
		/* The session is already connected. If we get a failure on
		* *sending* the request, try it again immediately with a new
		* connection. */
		rq_retry = 1;
	} else {
		rq_retry = 0;
		if ((result = openconnect_open_https(vpninfo))) {
			vpn_progress(vpninfo, PRG_ERR,
				     _("Failed to open HTTPS connection to %s\n"),
				     vpninfo->hostname);
			/* We really don't want to return -EINVAL if we have
			   failed to even connect to the server, because if
			   we do that openconnect_obtain_cookie() might try
			   again without XMLPOST... with the same result. */
			result = -EIO;
			goto out;
		}
	}

	if (vpninfo->dump_http_traffic)
		dump_buf(vpninfo, '>', buf->data);

	result = vpninfo->ssl_write(vpninfo, buf->data, buf->pos);
	if (rq_retry && result < 0) {
		openconnect_close_https(vpninfo, 0);
		goto retry;
	}
	if (result < 0)
		goto out;

	result = process_http_response(vpninfo, 0, http_auth_hdrs, buf);
	if (result < 0) {
		/* We'll already have complained about whatever offended us */
		goto out;
	}
	if (vpninfo->dump_http_traffic && buf->pos)
		dump_buf(vpninfo, '<', buf->data);

	if (result == 401 && vpninfo->try_http_auth) {
		auth = 1;
		goto redirected;
	}
	if (result != 200 && vpninfo->redirect_url) {
		result = handle_redirect(vpninfo);
		if (result == 0) {
			if (!fetch_redirect)
				goto out;
			if (fetch_redirect == 2) {
				/* Juniper requires we GET after a redirected POST */
				method = "GET";
				request_body_type = NULL;
			}
			if (vpninfo->redirect_type == REDIR_TYPE_NEWHOST)
				clear_auth_states(vpninfo, vpninfo->http_auth, 1);
			goto redirected;
		}
		goto out;
	}
	if (!buf->pos || result != 200) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected %d result from server\n"),
			     result);
		result = -EINVAL;
		goto out;
	}

	*form_buf = buf->data;
	buf->data = NULL;
	result = buf->pos;

 out:
	buf_free(buf);
	/* On success, clear out all authentication state for the next request */
	clear_auth_states(vpninfo, vpninfo->http_auth, 1);
	return result;
}

char *openconnect_create_useragent(const char *base)
{
	char *uagent;

	if (asprintf(&uagent, "%s %s", base, openconnect_version_str) < 0)
		return NULL;

	return uagent;
}

static int proxy_gets(struct openconnect_info *vpninfo, char *buf, size_t len)
{
	int i = 0;
	int ret;

	if (len < 2)
		return -EINVAL;

	while ((ret = proxy_read(vpninfo, (void *)(buf + i), 1)) == 1) {
		if (buf[i] == '\n') {
			buf[i] = 0;
			if (i && buf[i-1] == '\r') {
				buf[i-1] = 0;
				i--;
			}
			return i;
		}
		i++;

		if (i >= len - 1) {
			buf[i] = 0;
			return i;
		}
	}
	buf[i] = 0;
	return i ?: ret;
}

static int proxy_write(struct openconnect_info *vpninfo, char *buf, size_t len)
{
	size_t count;
	int fd = vpninfo->proxy_fd;

	if (fd == -1)
		return -EINVAL;

	for (count = 0; count < len; ) {
		fd_set rd_set, wr_set;
		int maxfd = fd;
		int i;

		FD_ZERO(&wr_set);
		FD_ZERO(&rd_set);
		FD_SET(fd, &wr_set);
		cmd_fd_set(vpninfo, &rd_set, &maxfd);

		select(maxfd + 1, &rd_set, &wr_set, NULL, NULL);
		if (is_cancel_pending(vpninfo, &rd_set))
			return -EINTR;

		/* Not that this should ever be able to happen... */
		if (!FD_ISSET(fd, &wr_set))
			continue;

		i = send(fd, (void *)&buf[count], len - count, 0);
		if (i < 0)
			return -errno;

		count += i;
	}
	return count;
}

static int proxy_read(struct openconnect_info *vpninfo, char *buf, size_t len)
{
	size_t count;
	int fd = vpninfo->proxy_fd;

	if (fd == -1)
		return -EINVAL;

	for (count = 0; count < len; ) {
		fd_set rd_set;
		int maxfd = fd;
		int i;

		FD_ZERO(&rd_set);
		FD_SET(fd, &rd_set);
		cmd_fd_set(vpninfo, &rd_set, &maxfd);

		select(maxfd + 1, &rd_set, NULL, NULL, NULL);
		if (is_cancel_pending(vpninfo, &rd_set))
			return -EINTR;

		/* Not that this should ever be able to happen... */
		if (!FD_ISSET(fd, &rd_set))
			continue;

		i = recv(fd, (void *)&buf[count], len - count, 0);
		if (i < 0)
			return -errno;
		else if (i == 0)
			return -ECONNRESET;

		count += i;
	}
	return count;
}

static const char *socks_errors[] = {
	N_("request granted"),
	N_("general failure"),
	N_("connection not allowed by ruleset"),
	N_("network unreachable"),
	N_("host unreachable"),
	N_("connection refused by destination host"),
	N_("TTL expired"),
	N_("command not supported / protocol error"),
	N_("address type not supported")
};

static int socks_password_auth(struct openconnect_info *vpninfo)
{
	int ul, pl, i;
	char buf[1024];

	if (!vpninfo->proxy_user || !vpninfo->proxy_pass) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("SOCKS server requested username/password but we have none\n"));
		return -EIO;
	}
	ul = strlen(vpninfo->proxy_user);
	pl = strlen(vpninfo->proxy_pass);

	if (ul > 255 || pl > 255) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Username and password for SOCKS authentication must be < 255 bytes\n"));
		return -EINVAL;
	}

	buf[0] = 1;
	buf[1] = ul;
	memcpy(buf + 2, vpninfo->proxy_user, ul);
	buf[2 + ul] = pl;
	memcpy(buf + 3 + ul, vpninfo->proxy_pass, pl);

	i = proxy_write(vpninfo, buf, 3 + ul + pl);
	/* Don't leave passwords lying around if we can easily avoid it... */
	memset(buf, 0, sizeof(buf));
	if (i < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error writing auth request to SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}


	if ((i = proxy_read(vpninfo, buf, 2)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error reading auth response from SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}

	if (buf[0] != 1) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected auth response from SOCKS proxy: %02x %02x\n"),
			     buf[0], buf[1]);
		return -EIO;
	}
	if (buf[1] == 0) {
		vpn_progress(vpninfo, PRG_DEBUG,
			     _("Authenticated to SOCKS server using password\n"));
		return 0;
	} else {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Password authentication to SOCKS server failed\n"));
		return -EIO;
	}
}

#define SOCKS_AUTH_NONE			0	/* RFC1928 */
#define SOCKS_AUTH_GSSAPI		1	/* RFC1961 */
#define SOCKS_AUTH_PASSWORD		2	/* RFC1929 */
#define SOCKS_AUTH_NO_ACCEPTABLE	0xff	/* RFC1928 */

static int process_socks_proxy(struct openconnect_info *vpninfo)
{
	char buf[1024];
	int i, nr_auth_methods = 0;

	buf[0] = 5; /* SOCKS version */

	buf[2 + nr_auth_methods++] = SOCKS_AUTH_NONE;
#if defined(HAVE_GSSAPI) || defined(_WIN32)
	if (vpninfo->proxy_auth[AUTH_TYPE_GSSAPI].state > AUTH_FAILED &&
	    !vpninfo->proxy_user && !vpninfo->proxy_pass)
		buf[2 + nr_auth_methods++] = SOCKS_AUTH_GSSAPI;
#endif
	if (vpninfo->proxy_auth[AUTH_TYPE_BASIC].state > AUTH_FAILED &&
	    vpninfo->proxy_user && vpninfo->proxy_pass)
		buf[2 + nr_auth_methods++] = SOCKS_AUTH_PASSWORD;

	buf[1] = nr_auth_methods;

	if ((i = proxy_write(vpninfo, buf, 2 + nr_auth_methods)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error writing auth request to SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}

	if ((i = proxy_read(vpninfo, buf, 2)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error reading auth response from SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}
	if (buf[0] != 5) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected auth response from SOCKS proxy: %02x %02x\n"),
			     buf[0], buf[1]);
		return -EIO;
	}
	switch ((unsigned char)buf[1]) {
	case SOCKS_AUTH_NONE:
		/* No authentication */
		break;

	case SOCKS_AUTH_GSSAPI:
#if defined(HAVE_GSSAPI) || defined(_WIN32)
		vpn_progress(vpninfo, PRG_DEBUG,
			     _("SOCKS server requested GSSAPI authentication\n"));
		if (socks_gssapi_auth(vpninfo))
			return -EIO;
		break;
#else
		/* This should never happen since we didn't ask for it! */
		vpn_progress(vpninfo, PRG_ERR,
			     _("SOCKS server requested GSSAPI authentication\n"));
		return -EIO;
#endif

	case SOCKS_AUTH_PASSWORD:
		vpn_progress(vpninfo, PRG_DEBUG,
			     _("SOCKS server requested password authentication\n"));
		if (socks_password_auth(vpninfo))
			return -EIO;
		break;

	case SOCKS_AUTH_NO_ACCEPTABLE:
		vpn_progress(vpninfo, PRG_ERR,
			     _("SOCKS server requires authentication\n"));
		vpn_progress(vpninfo, PRG_INFO,
			     _("This version of OpenConnect was built without GSSAPI support\n"));
		return -EIO;

	default:
		vpn_progress(vpninfo, PRG_ERR,
			     _("SOCKS server requested unknown authentication type %02x\n"),
			     (unsigned char)buf[1]);
		return -EIO;
	}

	vpn_progress(vpninfo, PRG_INFO,
		     _("Requesting SOCKS proxy connection to %s:%d\n"),
		     vpninfo->hostname, vpninfo->port);

	buf[0] = 5; /* SOCKS version */
	buf[1] = 1; /* CONNECT */
	buf[2] = 0; /* Reserved */
	buf[3] = 3; /* Address type is domain name */
	buf[4] = strlen(vpninfo->hostname);
	strcpy((char *)buf + 5, vpninfo->hostname);
	i = strlen(vpninfo->hostname) + 5;
	store_be16(buf + i, vpninfo->port);
	i += 2;

	if ((i = proxy_write(vpninfo, buf, i)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error writing connect request to SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}
	/* Read 5 bytes -- up to and including the first byte of the returned
	   address (which might be the length byte of a domain name) */
	if ((i = proxy_read(vpninfo, buf, 5)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error reading connect response from SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}
	if (i != 5 || buf[0] != 5) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected connect response from SOCKS proxy: %02x %02x...\n"),
			     buf[0], buf[1]);
		return -EIO;
	}
	if (buf[1]) {
		unsigned char err = buf[1];
		if (err < sizeof(socks_errors) / sizeof(socks_errors[0]))
			vpn_progress(vpninfo, PRG_ERR,
				     _("SOCKS proxy error %02x: %s\n"),
				     err, _(socks_errors[err]));
		else
			vpn_progress(vpninfo, PRG_ERR,
				     _("SOCKS proxy error %02x\n"), err);
		return -EIO;
	}

	/* Connect responses contain an address */
	switch (buf[3]) {
	case 1: /* Legacy IP */
		i = 5;
		break;
	case 3: /* Domain name */
		i = buf[4] + 2;
		break;
	case 4: /* IPv6 */
		i = 17;
		break;
	default:
		vpn_progress(vpninfo, PRG_ERR,
			     _("Unexpected address type %02x in SOCKS connect response\n"),
			     buf[3]);
		return -EIO;
	}

	if ((i = proxy_read(vpninfo, buf, i)) < 0) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Error reading connect response from SOCKS proxy: %s\n"),
			     strerror(-i));
		return i;
	}
	return 0;
}

static int process_http_proxy(struct openconnect_info *vpninfo)
{
	struct oc_text_buf *reqbuf;
	int result;
	int auth = vpninfo->proxy_close_during_auth;

	vpninfo->proxy_close_during_auth = 0;

	vpn_progress(vpninfo, PRG_INFO,
		     _("Requesting HTTP proxy connection to %s:%d\n"),
		     vpninfo->hostname, vpninfo->port);

 retry:
	reqbuf = buf_alloc();
	buf_append(reqbuf, "CONNECT %s:%d HTTP/1.1\r\n", vpninfo->hostname, vpninfo->port);
	if (vpninfo->port == 443)
		buf_append(reqbuf, "Host: %s\r\n", vpninfo->hostname);
	else
		buf_append(reqbuf, "Host: %s:%d\r\n", vpninfo->hostname, vpninfo->port);
	buf_append(reqbuf, "User-Agent: %s\r\n", vpninfo->useragent);
	buf_append(reqbuf, "Proxy-Connection: keep-alive\r\n");
	buf_append(reqbuf, "Connection: keep-alive\r\n");
	buf_append(reqbuf, "Accept-Encoding: identity\r\n");
	if (auth) {
		result = gen_authorization_hdr(vpninfo, 1, reqbuf);
		if (result) {
			buf_free(reqbuf);
			return result;
		}
		/* Forget existing challenges */
		clear_auth_states(vpninfo, vpninfo->proxy_auth, 0);
	}
	buf_append(reqbuf, "\r\n");

	if (buf_error(reqbuf))
		return buf_free(reqbuf);

	if (vpninfo->dump_http_traffic)
		dump_buf(vpninfo, '>', reqbuf->data);

	result = proxy_write(vpninfo, reqbuf->data, reqbuf->pos);
	if (result < 0) {
		buf_free(reqbuf);
		vpn_progress(vpninfo, PRG_ERR,
			     _("Sending proxy request failed: %s\n"),
			     strerror(-result));
		return result;
	}

	result = process_http_response(vpninfo, 1, proxy_auth_hdrs, reqbuf);
	buf_free(reqbuf);
	if (result < 0)
		return -EINVAL;

	if (result == 407) {
		/* If the proxy asked us to close the connection, do so */
		if (vpninfo->proxy_close_during_auth)
			return -EAGAIN;

		auth = 1;
		goto retry;
	}

	if (result == 200)
		return 0;

	vpn_progress(vpninfo, PRG_ERR,
		     _("Proxy CONNECT request failed: %d\n"), result);
	return -EIO;
}

int process_proxy(struct openconnect_info *vpninfo, int ssl_sock)
{
	int ret;

	vpninfo->proxy_fd = ssl_sock;
	vpninfo->ssl_read = proxy_read;
	vpninfo->ssl_write = proxy_write;
	vpninfo->ssl_gets = proxy_gets;

	if (!vpninfo->proxy_type || !strcmp(vpninfo->proxy_type, "http"))
		ret = process_http_proxy(vpninfo);
	else if (!strcmp(vpninfo->proxy_type, "socks") ||
		 !strcmp(vpninfo->proxy_type, "socks5"))
		ret = process_socks_proxy(vpninfo);
	else {
		vpn_progress(vpninfo, PRG_ERR, _("Unknown proxy type '%s'\n"),
			     vpninfo->proxy_type);
		ret = -EIO;
	}

	vpninfo->proxy_fd = -1;
	if (!vpninfo->proxy_close_during_auth)
		clear_auth_states(vpninfo, vpninfo->proxy_auth, 1);

	return ret;
}

int openconnect_set_http_proxy(struct openconnect_info *vpninfo,
			       const char *proxy)
{
	char *url = strdup(proxy), *p;
	int ret;

	if (!url)
		return -ENOMEM;

	free(vpninfo->proxy_type);
	vpninfo->proxy_type = NULL;
	free(vpninfo->proxy);
	vpninfo->proxy = NULL;

	ret = internal_parse_url(url, &vpninfo->proxy_type, &vpninfo->proxy,
				 &vpninfo->proxy_port, NULL, 80);
	if (ret)
		goto out;

	p = strchr(vpninfo->proxy, '@');
	if (p) {
		/* Proxy username/password */
		*p = 0;
		vpninfo->proxy_user = vpninfo->proxy;
		vpninfo->proxy = strdup(p + 1);
		p = strchr(vpninfo->proxy_user, ':');
		if (p) {
			*p = 0;
			vpninfo->proxy_pass = strdup(p + 1);
		}
	}

	if (vpninfo->proxy_type &&
	    strcmp(vpninfo->proxy_type, "http") &&
	    strcmp(vpninfo->proxy_type, "socks") &&
	    strcmp(vpninfo->proxy_type, "socks5")) {
		vpn_progress(vpninfo, PRG_ERR,
			     _("Only http or socks(5) proxies supported\n"));
		free(vpninfo->proxy_type);
		vpninfo->proxy_type = NULL;
		free(vpninfo->proxy);
		vpninfo->proxy = NULL;
		return -EINVAL;
	}
 out:
	free(url);
	return ret;
}

void http_common_headers(struct openconnect_info *vpninfo, struct oc_text_buf *buf)
{
	struct oc_vpn_option *opt;

	if (vpninfo->port == 443)
		buf_append(buf, "Host: %s\r\n", vpninfo->hostname);
	else
		buf_append(buf, "Host: %s:%d\r\n", vpninfo->hostname, vpninfo->port);
	buf_append(buf, "User-Agent: %s\r\n", vpninfo->useragent);

	if (vpninfo->cookies) {
		buf_append(buf, "Cookie: ");
		for (opt = vpninfo->cookies; opt; opt = opt->next)
			buf_append(buf, "%s=%s%s", opt->option,
				      opt->value, opt->next ? "; " : "\r\n");
	}
}