/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â Copyright The Mbed TLS Contributors                                          â
â                                                                              â
â Licensed under the Apache License, Version 2.0 (the "License");              â
â you may not use this file except in compliance with the License.             â
â You may obtain a copy of the License at                                      â
â                                                                              â
â     http://www.apache.org/licenses/LICENSE-2.0                               â
â                                                                              â
â Unless required by applicable law or agreed to in writing, software          â
â distributed under the License is distributed on an "AS IS" BASIS,            â
â WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.     â
â See the License for the specific language governing permissions and          â
â limitations under the License.                                               â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/fmt/conv.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/consts/exit.h"
#include "third_party/mbedtls/ctr_drbg.h"
#include "third_party/mbedtls/debug.h"
#include "third_party/mbedtls/entropy.h"
#include "third_party/mbedtls/net_sockets.h"
#include "third_party/mbedtls/ssl.h"
#include "third_party/mbedtls/x509_crt.h"

STATIC_YOINK("ssl_root_support");

#define MODE_NONE 0
#define MODE_FILE 1
#define MODE_SSL  2

#define DFL_MODE        MODE_NONE
#define DFL_FILENAME    "cert.crt"
#define DFL_CA_FILE     ""
#define DFL_CRL_FILE    ""
#define DFL_CA_PATH     "/zip/usr/share/ssl/root"
#define DFL_SERVER_NAME "localhost"
#define DFL_SERVER_PORT "4433"
#define DFL_DEBUG_LEVEL 0
#define DFL_PERMISSIVE  0

#define USAGE_IO                                             \
  "    ca_file=%%s          file containing top-level CAs\n" \
  "    ca_path=%%s          dir containing top-level CAs\n"  \
  "    crl_file=%%s         The single CRL file you want to use\n"

#define USAGE                                             \
  "\n usage: %s param=<>...\n"                            \
  "\n acceptable parameters:\n"                           \
  "    mode=file|ssl        default: none\n"              \
  "    filename=%%s         default: cert.crt\n" USAGE_IO \
  "    server_name=%%s      default: localhost\n"         \
  "    server_port=%%d      default: 4433\n"              \
  "    debug_level=%%d      default: 0 (disabled)\n"      \
  "    permissive=%%d       default: 0 (disabled)\n"      \
  "\n"

/*
 * global options
 */
struct options {
  int mode;                /* the mode to run the application in   */
  const char *filename;    /* filename of the certificate file     */
  const char *ca_file;     /* the file with the CA certificate(s)  */
  const char *crl_file;    /* the file with the CRL to use         */
  const char *ca_path;     /* the path with the CA certificate(s) reside */
  const char *server_name; /* hostname of the server (client only) */
  const char *server_port; /* port on which the ssl service runs   */
  int debug_level;         /* level of debugging                   */
  int permissive;          /* permissive parsing                   */
} opt;

static void my_debug(void *ctx, int level, const char *file, int line,
                     const char *str) {
  fprintf((FILE *)ctx, "%s:%04d: %s", file, line, str);
  fflush((FILE *)ctx);
}

static int my_verify(void *data, mbedtls_x509_crt *crt, int depth,
                     uint32_t *flags) {
  char buf[1024];
  printf("\nVerify requested for (Depth %d):\n", depth);
  mbedtls_x509_crt_info(buf, sizeof(buf) - 1, "", crt);
  printf("%s", buf);
  if (*flags) {
    mbedtls_x509_crt_verify_info(buf, sizeof(buf), "  ! ", *flags);
    printf("%s\n", buf);
  }
  return 0;
}

mbedtls_net_context server_fd;
unsigned char buf[1024];
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt cacert;
mbedtls_x509_crl cacrl;

int main(int argc, char *argv[]) {
  int ret = 1;
  int exit_code = EXIT_FAILURE;
  int i, j;
  uint32_t flags;
  int verify = 0;
  char *p, *q;
  const char *pers = "cert_app";

  /*
   * Set to sane values
   */
  mbedtls_net_init(&server_fd);
  mbedtls_ctr_drbg_init(&ctr_drbg);
  mbedtls_ssl_init(&ssl);
  mbedtls_ssl_config_init(&conf);
  mbedtls_x509_crt_init(&cacert);
#if defined(MBEDTLS_X509_CRL_PARSE_C)
  mbedtls_x509_crl_init(&cacrl);
#else
  /* Zeroize structure as CRL parsing is not supported and we have to pass
     it to the verify function */
  memset(&cacrl, 0, sizeof(mbedtls_x509_crl));
#endif

  if (argc == 0) {
  usage:
    printf(USAGE, program_invocation_name);
    goto exit;
  }

  opt.mode = DFL_MODE;
  opt.filename = DFL_FILENAME;
  opt.ca_file = DFL_CA_FILE;
  opt.crl_file = DFL_CRL_FILE;
  opt.ca_path = DFL_CA_PATH;
  opt.server_name = DFL_SERVER_NAME;
  opt.server_port = DFL_SERVER_PORT;
  opt.debug_level = DFL_DEBUG_LEVEL;
  opt.permissive = DFL_PERMISSIVE;

  for (i = 1; i < argc; i++) {
    p = argv[i];
    if ((q = strchr(p, '=')) == NULL) goto usage;
    *q++ = '\0';

    for (j = 0; p + j < q; j++) {
      if (argv[i][j] >= 'A' && argv[i][j] <= 'Z') argv[i][j] |= 0x20;
    }

    if (strcmp(p, "mode") == 0) {
      if (strcmp(q, "file") == 0)
        opt.mode = MODE_FILE;
      else if (strcmp(q, "ssl") == 0)
        opt.mode = MODE_SSL;
      else
        goto usage;
    } else if (strcmp(p, "filename") == 0)
      opt.filename = q;
    else if (strcmp(p, "ca_file") == 0)
      opt.ca_file = q;
    else if (strcmp(p, "crl_file") == 0)
      opt.crl_file = q;
    else if (strcmp(p, "ca_path") == 0)
      opt.ca_path = q;
    else if (strcmp(p, "server_name") == 0)
      opt.server_name = q;
    else if (strcmp(p, "server_port") == 0)
      opt.server_port = q;
    else if (strcmp(p, "debug_level") == 0) {
      opt.debug_level = atoi(q);
      if (opt.debug_level < 0 || opt.debug_level > 65535) goto usage;
    } else if (strcmp(p, "permissive") == 0) {
      opt.permissive = atoi(q);
      if (opt.permissive < 0 || opt.permissive > 1) goto usage;
    } else
      goto usage;
  }

  /*
   * 1.1. Load the trusted CA
   */
  printf("  . Loading the CA root certificate ...");
  fflush(stdout);

  if (strlen(opt.ca_path)) {
    if ((ret = mbedtls_x509_crt_parse_path(&cacert, opt.ca_path)) < 0) {
      printf(" failed\n  !  mbedtls_x509_crt_parse_path returned -0x%x\n\n",
             (unsigned int)-ret);
      goto exit;
    }

    verify = 1;
  } else if (strlen(opt.ca_file)) {
    if ((ret = mbedtls_x509_crt_parse_file(&cacert, opt.ca_file)) < 0) {
      printf(" failed\n  !  mbedtls_x509_crt_parse_file returned -0x%x\n\n",
             (unsigned int)-ret);
      goto exit;
    }

    verify = 1;
  }

  printf(" ok (%d skipped)\n", ret);

#if defined(MBEDTLS_X509_CRL_PARSE_C)
  if (strlen(opt.crl_file)) {
    if ((ret = mbedtls_x509_crl_parse_file(&cacrl, opt.crl_file)) != 0) {
      printf(" failed\n  !  mbedtls_x509_crl_parse returned -0x%x\n\n",
             (unsigned int)-ret);
      goto exit;
    }

    verify = 1;
  }
#endif

  if (opt.mode == MODE_FILE) {
    mbedtls_x509_crt crt;
    mbedtls_x509_crt *cur = &crt;
    mbedtls_x509_crt_init(&crt);

    /*
     * 1.1. Load the certificate(s)
     */
    printf("\n  . Loading the certificate(s) ...");
    fflush(stdout);

    ret = mbedtls_x509_crt_parse_file(&crt, opt.filename);

    if (ret < 0) {
      printf(" failed\n  !  mbedtls_x509_crt_parse_file returned -0x%04x\n\n",
             -ret);
      mbedtls_x509_crt_free(&crt);
      goto exit;
    }

    if (opt.permissive == 0 && ret > 0) {
      printf(" failed\n  !  mbedtls_x509_crt_parse failed to parse %d "
             "certificates\n\n",
             ret);
      mbedtls_x509_crt_free(&crt);
      goto exit;
    }

    printf(" ok\n");

    /*
     * 1.2 Print the certificate(s)
     */
    while (cur != NULL) {
      printf("  . Peer certificate information    ...\n");
      ret = mbedtls_x509_crt_info((char *)buf, sizeof(buf) - 1, "      ", cur);
      if (ret == -1) {
        printf(" failed\n  !  mbedtls_x509_crt_info returned -0x%04x\n\n",
               -ret);
        mbedtls_x509_crt_free(&crt);
        goto exit;
      }

      printf("%s\n", buf);

      cur = cur->next;
    }

    /*
     * 1.3 Verify the certificate
     */
    if (verify) {
      printf("  . Verifying X.509 certificate...");

      if ((ret = mbedtls_x509_crt_verify(&crt, &cacert, &cacrl, NULL, &flags,
                                         my_verify, NULL)) != 0) {
        char vrfy_buf[512];

        printf(" failed\n");

        mbedtls_x509_crt_verify_info(vrfy_buf, sizeof(vrfy_buf), "  ! ", flags);

        printf("%s\n", vrfy_buf);
      } else
        printf(" ok\n");
    }

    mbedtls_x509_crt_free(&crt);
  } else if (opt.mode == MODE_SSL) {
    /*
     * 1. Initialize the RNG and the session data
     */
    printf("\n  . Seeding the random number generator...");
    fflush(stdout);

    mbedtls_entropy_init(&entropy);
    if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
                                     (const unsigned char *)pers,
                                     strlen(pers))) != 0) {
      printf(" failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret);
      goto ssl_exit;
    }

    printf(" ok\n");

#if defined(MBEDTLS_DEBUG_C)
    mbedtls_debug_set_threshold(opt.debug_level);
#endif

    /*
     * 2. Start the connection
     */
    printf("  . Connecting to tcp/%s/%s...\n", opt.server_name,
           opt.server_port);

    if ((ret = mbedtls_net_connect(&server_fd, opt.server_name, opt.server_port,
                                   MBEDTLS_NET_PROTO_TCP)) != 0) {
      printf("  ! mbedtls_net_connect returned -0x%04x\n\n", -ret);
      goto ssl_exit;
    }

    /*
     * 3. Setup stuff
     */
    if ((ret = mbedtls_ssl_config_defaults(&conf, MBEDTLS_SSL_IS_CLIENT,
                                           MBEDTLS_SSL_TRANSPORT_STREAM,
                                           MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
      printf("  ! mbedtls_ssl_config_defaults returned -0x%04x\n\n", -ret);
      goto exit;
    }

    if (verify) {
      mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_REQUIRED);
      mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL);
      mbedtls_ssl_conf_verify(&conf, my_verify, NULL);
    } else
      mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_NONE);

    mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
    mbedtls_ssl_conf_dbg(&conf, my_debug, stdout);

    if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0) {
      printf("  ! mbedtls_ssl_setup returned -0x%04x\n\n", -ret);
      goto ssl_exit;
    }

    if ((ret = mbedtls_ssl_set_hostname(&ssl, opt.server_name)) != 0) {
      printf("  ! mbedtls_ssl_set_hostname returned -0x%04x\n\n", -ret);
      goto ssl_exit;
    }

    mbedtls_ssl_set_bio(&ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv,
                        NULL);

    /*
     * 4. Handshake
     */
    while ((ret = mbedtls_ssl_handshake(&ssl)) != 0) {
      if (ret != MBEDTLS_ERR_SSL_WANT_READ &&
          ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
        printf("  ! mbedtls_ssl_handshake returned -0x%04x\n\n", -ret);
        goto ssl_exit;
      }
    }

    /*
     * 5. Print the certificate
     */
#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    printf("  . Peer certificate information    ... skipped\n");
#else
    printf("  . Peer certificate information    ...\n");
    ret = mbedtls_x509_crt_info((char *)buf, sizeof(buf) - 1, "      ",
                                mbedtls_ssl_get_peer_cert(&ssl));
    if (ret == -1) {
      printf(" failed\n  !  mbedtls_x509_crt_info returned -0x%04x\n\n", -ret);
      goto ssl_exit;
    }

    printf("%s\n", buf);
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */

    mbedtls_ssl_close_notify(&ssl);

  ssl_exit:
    mbedtls_ssl_free(&ssl);
    mbedtls_ssl_config_free(&conf);
  } else
    goto usage;

  exit_code = MBEDTLS_EXIT_SUCCESS;

exit:

  mbedtls_net_free(&server_fd);
  mbedtls_x509_crt_free(&cacert);
#if defined(MBEDTLS_X509_CRL_PARSE_C)
  mbedtls_x509_crl_free(&cacrl);
#endif
  mbedtls_ctr_drbg_free(&ctr_drbg);
  mbedtls_entropy_free(&entropy);

  mbedtls_exit(exit_code);
}
