/*
 * Copyright (c) 2015 Marko Kreen <markokr@gmail.com>
 * Copyright (c) 2016 Bob Beck <beck@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <arpa/inet.h>
#include <netinet/in.h>

#include <openssl/err.h>
#include <openssl/ocsp.h>
#include <openssl/x509.h>

#include <tls.h>
#include "tls_internal.h"

#define MAXAGE_SEC (14*24*60*60)
#define JITTER_SEC (60)

/*
 * State for request.
 */

static struct tls_ocsp *
tls_ocsp_new(void)
{
   return (calloc(1, sizeof(struct tls_ocsp)));
}

void
tls_ocsp_free(struct tls_ocsp *ocsp)
{
   if (ocsp == NULL)
      return;

   X509_free(ocsp->main_cert);
   free(ocsp->ocsp_result);
   free(ocsp->ocsp_url);

   free(ocsp);
}

static int
tls_ocsp_asn1_parse_time(struct tls *ctx, ASN1_GENERALIZEDTIME *gt, time_t *gt_time)
{
   struct tm tm;

   if (gt == NULL)
      return -1;
   /* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */
   if (ASN1_time_parse(gt->data, gt->length, &tm,
      V_ASN1_GENERALIZEDTIME) == -1)
      return -1;
#ifndef __VMS
        if ((*gt_time = timegm(&tm)) == -1)
                return -1;
#else
        if ((int)(*gt_time = timegm(&tm)) == -1)
                return -1;
#endif
   return 0;
}

static int
tls_ocsp_fill_info(struct tls *ctx, int response_status, int cert_status,
    int crl_reason, ASN1_GENERALIZEDTIME *revtime,
    ASN1_GENERALIZEDTIME *thisupd, ASN1_GENERALIZEDTIME *nextupd)
{
   struct tls_ocsp_result *info = NULL;

   free(ctx->ocsp->ocsp_result);
   ctx->ocsp->ocsp_result = NULL;

   if ((info = calloc(1, sizeof (struct tls_ocsp_result))) == NULL) {
      tls_set_error(ctx, "calloc");
      return -1;
   }
   info->response_status = response_status;
   info->cert_status = cert_status;
   info->crl_reason = crl_reason;
   if (info->response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
      info->result_msg =
          OCSP_response_status_str(info->response_status);
   } else if (info->cert_status != V_OCSP_CERTSTATUS_REVOKED) {
      info->result_msg = OCSP_cert_status_str(info->cert_status);
   } else {
      info->result_msg = OCSP_crl_reason_str(info->crl_reason);
   }
   info->revocation_time = info->this_update = info->next_update = -1;
   if (revtime != NULL &&
       tls_ocsp_asn1_parse_time(ctx, revtime, &info->revocation_time) != 0) {
      tls_set_error(ctx,
          "unable to parse revocation time in OCSP reply");
      goto err;
   }
   if (thisupd != NULL &&
       tls_ocsp_asn1_parse_time(ctx, thisupd, &info->this_update) != 0) {
      tls_set_error(ctx,
          "unable to parse this update time in OCSP reply");
      goto err;
   }
   if (nextupd != NULL &&
       tls_ocsp_asn1_parse_time(ctx, nextupd, &info->next_update) != 0) {
      tls_set_error(ctx,
          "unable to parse next update time in OCSP reply");
      goto err;
   }
   ctx->ocsp->ocsp_result = info;
   return 0;

 err:
   free(info);
   return -1;
}

static OCSP_CERTID *
tls_ocsp_get_certid(X509 *main_cert, STACK_OF(X509) *extra_certs,
    SSL_CTX *ssl_ctx)
{
   X509_NAME *issuer_name;
   X509 *issuer;
#if WCME_OPENSSL_SINCE_110
        X509_STORE_CTX *storectx = NULL;
        X509_OBJECT *tmpobj = NULL;
#else
        X509_STORE_CTX storectx;
        X509_OBJECT tmpobj;
#endif
   OCSP_CERTID *cid = NULL;
   X509_STORE *store;

   if ((issuer_name = X509_get_issuer_name(main_cert)) == NULL)
      return NULL;

   if (extra_certs != NULL) {
      issuer = X509_find_by_subject(extra_certs, issuer_name);
      if (issuer != NULL)
         return OCSP_cert_to_id(NULL, main_cert, issuer);
   }

   if ((store = SSL_CTX_get_cert_store(ssl_ctx)) == NULL)
      return NULL;
#if WCME_OPENSSL_SINCE_110
        storectx = X509_STORE_CTX_new();
        tmpobj = X509_OBJECT_new();
        if (X509_STORE_CTX_init(storectx, store, main_cert, extra_certs) != 1)
                return NULL;
        if (X509_STORE_get_by_subject(storectx, X509_LU_X509, issuer_name,
                tmpobj) == 1) {
                cid = OCSP_cert_to_id(NULL, main_cert,
                                      X509_OBJECT_get0_X509(tmpobj));
                X509_OBJECT_free(tmpobj);
        }
        X509_STORE_CTX_cleanup(storectx);
#else
        if (X509_STORE_CTX_init(&storectx, store, main_cert, extra_certs) != 1)
                return NULL;
        if (X509_STORE_get_by_subject(&storectx, X509_LU_X509, issuer_name,
                &tmpobj) == 1) {
                cid = OCSP_cert_to_id(NULL, main_cert, tmpobj.data.x509);
                X509_OBJECT_free_contents(&tmpobj);
        }
        X509_STORE_CTX_cleanup(&storectx);
#endif
   return cid;
}

struct tls_ocsp *
tls_ocsp_setup_from_peer(struct tls *ctx)
{
   struct tls_ocsp *ocsp = NULL;
   STACK_OF(OPENSSL_STRING) *ocsp_urls = NULL;

   if ((ocsp = tls_ocsp_new()) == NULL)
      goto err;

   /* steal state from ctx struct */
   ocsp->main_cert = SSL_get_peer_certificate(ctx->ssl_conn);
   ocsp->extra_certs = SSL_get_peer_cert_chain(ctx->ssl_conn);
   if (ocsp->main_cert == NULL) {
      tls_set_errorx(ctx, "no peer certificate for OCSP");
      goto err;
   }

   ocsp_urls = X509_get1_ocsp(ocsp->main_cert);
   if (ocsp_urls == NULL) {
      tls_set_errorx(ctx, "no OCSP URLs in peer certificate");
      goto err;
   }

   ocsp->ocsp_url = strdup(sk_OPENSSL_STRING_value(ocsp_urls, 0));
   if (ocsp->ocsp_url == NULL) {
      tls_set_errorx(ctx, "out of memory");
      goto err;
   }

   X509_email_free(ocsp_urls);
   return ocsp;

 err:
   tls_ocsp_free(ocsp);
   X509_email_free(ocsp_urls);
   return NULL;
}

static int
tls_ocsp_verify_response(struct tls *ctx, OCSP_RESPONSE *resp)
{
   OCSP_BASICRESP *br = NULL;
   ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL;
   OCSP_CERTID *cid = NULL;
   STACK_OF(X509) *combined = NULL;
   int response_status=0, cert_status=0, crl_reason=0;
   int ret = -1;
   unsigned long flags;

   if ((br = OCSP_response_get1_basic(resp)) == NULL) {
      tls_set_errorx(ctx, "cannot load ocsp reply");
      goto err;
   }

   /*
    * Skip validation of 'extra_certs' as this should be done
    * already as part of main handshake.
    */
   flags = OCSP_TRUSTOTHER;

   /* now verify */
   if (OCSP_basic_verify(br, ctx->ocsp->extra_certs,
      SSL_CTX_get_cert_store(ctx->ssl_ctx), flags) != 1) {
      tls_set_error(ctx, "ocsp verify failed");
      goto err;
   }

   /* signature OK, look inside */
   response_status = OCSP_response_status(resp);
   if (response_status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
      tls_set_errorx(ctx, "ocsp verify failed: response - %s",
          OCSP_response_status_str(response_status));
      goto err;
   }

   cid = tls_ocsp_get_certid(ctx->ocsp->main_cert,
       ctx->ocsp->extra_certs, ctx->ssl_ctx);
   if (cid == NULL) {
      tls_set_errorx(ctx, "ocsp verify failed: no issuer cert");
      goto err;
   }

   if (OCSP_resp_find_status(br, cid, &cert_status, &crl_reason,
       &revtime, &thisupd, &nextupd) != 1) {
      tls_set_errorx(ctx, "ocsp verify failed: no result for cert");
      goto err;
   }

   if (OCSP_check_validity(thisupd, nextupd, JITTER_SEC,
       MAXAGE_SEC) != 1) {
      tls_set_errorx(ctx,
          "ocsp verify failed: ocsp response not current");
      goto err;
   }

   if (tls_ocsp_fill_info(ctx, response_status, cert_status,
       crl_reason, revtime, thisupd, nextupd) != 0)
      goto err;

   /* finally can look at status */
   if (cert_status != V_OCSP_CERTSTATUS_GOOD && cert_status !=
       V_OCSP_CERTSTATUS_UNKNOWN) {
      tls_set_errorx(ctx, "ocsp verify failed: revoked cert - %s",
                OCSP_crl_reason_str(crl_reason));
      goto err;
   }
   ret = 0;

 err:
   sk_X509_free(combined);
   OCSP_CERTID_free(cid);
   OCSP_BASICRESP_free(br);
   return ret;
}

/*
 * Process a raw OCSP response from an OCSP server request.
 * OCSP details can then be retrieved with tls_peer_ocsp_* functions.
 * returns 0 if certificate ok, -1 otherwise.
 */
static int
tls_ocsp_process_response_internal(struct tls *ctx, const unsigned char *response,
    size_t size)
{
   int ret;
   OCSP_RESPONSE *resp;

   resp = d2i_OCSP_RESPONSE(NULL, &response, size);
   if (resp == NULL) {
      tls_ocsp_free(ctx->ocsp);
      ctx->ocsp = NULL;
      tls_set_error(ctx, "unable to parse OCSP response");
      return -1;
   }
   ret = tls_ocsp_verify_response(ctx, resp);
   OCSP_RESPONSE_free(resp);
   return ret;
}

/* TLS handshake verification callback for stapled requests */
int
tls_ocsp_verify_cb(SSL *ssl, void *arg)
{
   const unsigned char *raw = NULL;
   int size, res = -1;
   struct tls *ctx;

   if ((ctx = SSL_get_app_data(ssl)) == NULL)
      return -1;

   size = SSL_get_tlsext_status_ocsp_resp(ssl, &raw);
   if (size <= 0) {
      if (ctx->config->ocsp_require_stapling) {
         tls_set_errorx(ctx, "no stapled OCSP response provided");
         return 0;
      }
      return 1;
   }

   tls_ocsp_free(ctx->ocsp);
   if ((ctx->ocsp = tls_ocsp_setup_from_peer(ctx)) == NULL)
      return 0;

   if (ctx->config->verify_cert == 0 || ctx->config->verify_time == 0)
      return 1;

   res = tls_ocsp_process_response_internal(ctx, raw, size);

   return (res == 0) ? 1 : 0;
}



/* Staple the OCSP information in ctx->ocsp to the server handshake. */
int
tls_ocsp_stapling_cb(SSL *ssl, void *arg)
{
   int ret = SSL_TLSEXT_ERR_ALERT_FATAL;
   unsigned char *ocsp_staple = NULL;
   struct tls *ctx;

   if ((ctx = SSL_get_app_data(ssl)) == NULL)
      goto err;

   if (ctx->keypair == NULL || ctx->keypair->ocsp_staple == NULL ||
       ctx->keypair->ocsp_staple_len == 0)
      return SSL_TLSEXT_ERR_NOACK;

   if ((ocsp_staple = malloc(ctx->keypair->ocsp_staple_len)) == NULL)
      goto err;

   memcpy(ocsp_staple, ctx->keypair->ocsp_staple,
       ctx->keypair->ocsp_staple_len);

   if (SSL_set_tlsext_status_ocsp_resp(ctx->ssl_conn, ocsp_staple,
       ctx->keypair->ocsp_staple_len) != 1)
      goto err;

   ret = SSL_TLSEXT_ERR_OK;
 err:
   if (ret != SSL_TLSEXT_ERR_OK)
      free(ocsp_staple);

   return ret;
}

/*
 * Public API
 */

/* Retrieve OCSP URL from peer certificate, if present. */
const char *
tls_peer_ocsp_url(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return NULL;
   return ctx->ocsp->ocsp_url;
}

const char *
tls_peer_ocsp_result(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return NULL;
   if (ctx->ocsp->ocsp_result == NULL)
      return NULL;
   return ctx->ocsp->ocsp_result->result_msg;
}

int
tls_peer_ocsp_response_status(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->response_status;
}

int
tls_peer_ocsp_cert_status(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->cert_status;
}

int
tls_peer_ocsp_crl_reason(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->crl_reason;
}

time_t
tls_peer_ocsp_this_update(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->this_update;
}

time_t
tls_peer_ocsp_next_update(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->next_update;
}

time_t
tls_peer_ocsp_revocation_time(struct tls *ctx)
{
   if (ctx->ocsp == NULL)
      return -1;
   if (ctx->ocsp->ocsp_result == NULL)
      return -1;
   return ctx->ocsp->ocsp_result->revocation_time;
}

int
tls_ocsp_process_response(struct tls *ctx, const unsigned char *response,
    size_t size)
{
   if ((ctx->state & TLS_HANDSHAKE_COMPLETE) == 0)
      return -1;
   return tls_ocsp_process_response_internal(ctx, response, size);
}