/***************************************************************************
 * proxy_http.c -- HTTP Connect proxying.                                  *
 *                                                                         *
 ***********************IMPORTANT NSOCK LICENSE TERMS***********************
 *
 * The nsock parallel socket event library is (C) 1999-2024 Nmap Software LLC
 * This library is free software; you may redistribute and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; Version 2. This guarantees your right to use, modify, and
 * redistribute this software under certain conditions. If this license is
 * unacceptable to you, Nmap Software LLC may be willing to sell alternative
 * licenses (contact sales@nmap.com ).
 *
 * As a special exception to the GPL terms, Nmap Software LLC grants permission
 * to link the code of this program with any version of the OpenSSL library
 * which is distributed under a license identical to that listed in the included
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 * the two. You must obey the GNU GPL in all respects for all of the code used
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 *
 * If you received these files with a written license agreement stating terms
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 ***************************************************************************/

/* $Id $ */

#define _GNU_SOURCE
#include <stdio.h>

#include "nsock.h"
#include "nsock_internal.h"
#include "nsock_log.h"
#include <string.h>

#define DEFAULT_PROXY_PORT_HTTP 8080


extern struct timeval nsock_tod;
extern const struct proxy_spec ProxySpecHttp;


static int proxy_http_node_new(struct proxy_node **node, const struct uri *uri) {
  int rc;
  struct proxy_node *proxy;

  proxy = (struct proxy_node *)safe_zalloc(sizeof(struct proxy_node));
  proxy->spec = &ProxySpecHttp;

  rc = proxy_resolve(uri->host, (struct sockaddr *)&proxy->ss, &proxy->sslen, AF_UNSPEC);
  if (rc < 0) {
    free(proxy);
    *node = NULL;
    return -1;
  }

  if (uri->port == -1)
    proxy->port = DEFAULT_PROXY_PORT_HTTP;
  else
    proxy->port = (unsigned short)uri->port;

  rc = asprintf(&proxy->nodestr, "http://%s:%d", uri->host, proxy->port);
  if (rc < 0) {
    /* asprintf() failed for some reason but this is not a disaster (yet).
     * Set nodestr to NULL and try to keep on going. */
    proxy->nodestr = NULL;
  }

  *node = proxy;

  return 1;
}

static void proxy_http_node_delete(struct proxy_node *node) {
  if (!node)
    return;

  free(node->nodestr);

  free(node);
}

static int handle_state_initial(struct npool *nsp, struct nevent *nse, void *udata) {
  struct proxy_chain_context *px_ctx = nse->iod->px_ctx;
  struct sockaddr_storage *ss;
  size_t sslen;
  unsigned short port;
  struct proxy_node *next;
  int timeout;

  px_ctx->px_state = PROXY_STATE_HTTP_TCP_CONNECTED;

  next = proxy_ctx_node_next(px_ctx);
  if (next) {
    ss    = &next->ss;
    sslen = next->sslen;
    port  = next->port;
  } else {
    ss    = &px_ctx->target_ss;
    sslen = px_ctx->target_sslen;
    port  = px_ctx->target_port;
  }

  timeout = TIMEVAL_MSEC_SUBTRACT(nse->timeout, nsock_tod);

  nsock_printf(nsp, (nsock_iod)nse->iod, nsock_proxy_ev_dispatch,
               timeout, udata, "CONNECT %s:%d HTTP/1.1\r\n\r\n",
               inet_ntop_ez(ss, sslen), (int)port);

  nsock_readlines(nsp, (nsock_iod)nse->iod, nsock_proxy_ev_dispatch,
                  timeout, udata, 1);

  return 0;
}

static int handle_state_tcp_connected(struct npool *nsp, struct nevent *nse, void *udata) {
  struct proxy_chain_context *px_ctx = nse->iod->px_ctx;
  char *res;
  int reslen;

  res = nse_readbuf(nse, &reslen);

  /* TODO string check!! */
  if (!((reslen >= 15) && strstr(res, "200 OK"))) {
    struct proxy_node *node = px_ctx->px_current;

    nsock_log_debug("Connection refused from proxy %s", node->nodestr);
    return -EINVAL;
  }

  px_ctx->px_state = PROXY_STATE_HTTP_TUNNEL_ESTABLISHED;

  if (proxy_ctx_node_next(px_ctx) == NULL) {
    forward_event(nsp, nse, udata);
  } else {
    px_ctx->px_current = proxy_ctx_node_next(px_ctx);
    px_ctx->px_state   = PROXY_STATE_INITIAL;
    nsock_proxy_ev_dispatch(nsp, nse, udata);
  }
  return 0;
}

static void proxy_http_handler(nsock_pool nspool, nsock_event nsevent, void *udata) {
  int rc = 0;
  struct npool *nsp = (struct npool *)nspool;
  struct nevent *nse = (struct nevent *)nsevent;

  switch (nse->iod->px_ctx->px_state) {
    case PROXY_STATE_INITIAL:
      rc = handle_state_initial(nsp, nse, udata);
      break;

    case PROXY_STATE_HTTP_TCP_CONNECTED:
      if (nse->type == NSE_TYPE_READ)
        rc = handle_state_tcp_connected(nsp, nse, udata);
      break;

    case PROXY_STATE_HTTP_TUNNEL_ESTABLISHED:
      forward_event(nsp, nse, udata);
      break;

    default:
      fatal("Invalid proxy state!");
  }

  if (rc) {
    nse->status = NSE_STATUS_PROXYERROR;
    forward_event(nsp, nse, udata);
  }
}


/* ---- PROXY DEFINITION ---- */
static const struct proxy_op ProxyOpsHttp = {
  proxy_http_node_new,
  proxy_http_node_delete,
  proxy_http_handler,
};

const struct proxy_spec ProxySpecHttp = {
  "http://",
  PROXY_TYPE_HTTP,
  &ProxyOpsHttp,
};