GET request for a file; download a file using an HTTP request. OpenSSL

get.c

/*
 * Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/err.h>
#include <openssl/ssl.h>
#include <string.h>

int main(int argc, char **argv) {
  BIO *sbio = NULL, *out = NULL;
  int len;
  char tmpbuf[1024];
  SSL_CTX *ctx;
  SSL_CONF_CTX *cctx;
  SSL *ssl;
  char **args = argv + 1;
  const char *connect_str = "juventudedesporto.cplp.org:443";
  int nargs = argc - 1;
  ctx = SSL_CTX_new(TLS_client_method());
  cctx = SSL_CONF_CTX_new();
  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CLIENT);
  SSL_CONF_CTX_set_ssl_ctx(cctx, ctx);
  while (*args && **args == '-') {
    int rv;
    /* Parse standard arguments */
    rv = SSL_CONF_cmd_argv(cctx, &nargs, &args);
    if (rv == -3) {
      fprintf(stderr, "Missing argument for %s\n", *args);
      goto end;
    }
    if (rv < 0) {
      fprintf(stderr, "Error in command %s\n", *args);
      ERR_print_errors_fp(stderr);
      goto end;
    }
    /* If rv > 0 we processed something so proceed to next arg */
    if (rv > 0)
      continue;
    /* Otherwise application specific argument processing */
    if (strcmp(*args, "-connect") == 0) {
      connect_str = args[1];
      if (connect_str == NULL) {
        fprintf(stderr, "Missing -connect argument\n");
        goto end;
      }
      args += 2;
      nargs -= 2;
      continue;
    } else {
      fprintf(stderr, "Unknown argument %s\n", *args);
      goto end;
    }
  }

  if (!SSL_CONF_CTX_finish(cctx)) {
    fprintf(stderr, "Finish error\n");
    ERR_print_errors_fp(stderr);
    goto end;
  }

  /*
   * We'd normally set some stuff like the verify paths and * mode here
   * because as things stand this will connect to * any server whose
   * certificate is signed by any CA.
   */

  sbio = BIO_new_ssl_connect(ctx);

  BIO_get_ssl(sbio, &ssl);

  if (!ssl) {
    fprintf(stderr, "Can't locate SSL pointer\n");
    goto end;
  }

  /* We might want to do other things with ssl here */

  BIO_set_conn_hostname(sbio, connect_str);

  FILE *fp = fopen("f.pdf", "wb");
  out = BIO_new_fp(fp, BIO_NOCLOSE);
  if (BIO_do_connect(sbio) <= 0) {
    fprintf(stderr, "Error connecting to server\n");
    ERR_print_errors_fp(stderr);
    goto end;
  }

  /* Could examine ssl here to get connection info */

  BIO_puts(
      sbio,
      "GET /files/sample-pdf_9359.pdf HTTP/1.1\r\n"
      "Host: juventudedesporto.cplp.org\r\n"
      "Accept: "
      "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n"
      "User-Agent: Mozilla/5.0 (X11; CrOS x86_64 8172.45.0) AppleWebKit/537.36 "
      "User-Agent: Mozilla/5.0 (X11; CrOS x86_64 8172.45.0) AppleWebKit/537.36 "
      "(KHTML, "
      "like Gecko) Chrome/51.0.2704.64 Safari/537.36\r\n"
      "Accept-Language: en-US,en;q=0.5\r\n"
      "Connection: keep-alive\r\n\r\n");
  int total = 0;
  for (;;) {
    len = BIO_read(sbio, tmpbuf, 1024);
    printf("\rread %-4d bytes, total %-7d", len, total += len);
    fflush(stdout);
    for (int i = 0; i < len - 3; i++) {
      if (tmpbuf[i] == '\r' && tmpbuf[i + 1] == '\n' && tmpbuf[i + 2] == '\r' &&
          tmpbuf[i + 3] == '\n') {
        /*  skip response header */
        BIO_write(out, tmpbuf + i + 4, (len - i) - 4);
        for (;;) {
          len = BIO_read(sbio, tmpbuf, 1024);
          printf("\rread %-4d bytes, total %-7d", len, total += len);
          fflush(stdout);
          if (len <= 0)
            goto end;
          BIO_write(out, tmpbuf, len);
        }
      }
    }
    if (len <= 0)
      break;
  }
end:
  putchar('\n');
  SSL_CONF_CTX_free(cctx);
  BIO_free_all(sbio);
  BIO_free(out);
  fclose(fp);
  return 0;
}