curl: prevent binary output spewed to terminal

... unless "--output -" is used. Binary detection is done by simply checking for a binary zero in early data. Added test 1425 1426 to verify. Closes #1512
curl · Jun 16, 2017 · 5385450afd61328e7d24b50eeffc2b1571cd9e2f · 5385450 · tobbbles · Jun 19, 2017
1 parent ce2cc56
commit 5385450afd61328e7d24b50eeffc2b1571cd9e2f
diff --git a/docs/TODO b/docs/TODO
@@ -140,7 +140,6 @@
 18.4 simultaneous parallel transfers
 18.5 provide formpost headers
 18.6 warning when setting an option
- 18.7 warning when sending binary output to terminal
 18.8 offer color-coded HTTP header output
 18.9 Choose the name of file in braces for complex URLs
 18.10 improve how curl works in a windows console window
@@ -933,11 +932,6 @@ that doesn't exist on the server, just like --ftp-create-dirs.
 This can be useful to tell when support for a particular feature hasn't been
 compiled into the library.

-18.7 warning when sending binary output to terminal
-
- Provide a way that prompts the user for confirmation before binary data is
- sent to the terminal, much in the style 'less' does it.
-
 18.8 offer color-coded HTTP header output

 By offering different color output on the header name and the header
diff --git a/src/tool_cb_wrt.c b/src/tool_cb_wrt.c
@@ -5,7 +5,7 @@
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
@@ -77,28 +77,38 @@ size_t tool_write_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
  size_t rc;
  struct OutStruct *outs = userdata;
  struct OperationConfig *config = outs->config;
+  size_t bytes = sz * nmemb;
+  bool isatty = config->global->isatty;

  /*
   * Once that libcurl has called back tool_write_cb() the returned value
   * is checked against the amount that was intended to be written, if
   * it does not match then it fails with CURLE_WRITE_ERROR. So at this
   * point returning a value different from sz*nmemb indicates failure.
   */
-  const size_t failure = (sz && nmemb) ? 0 : 1;
+  const size_t failure = bytes ? 0 : 1;

  if(!config)
    return failure;

 #ifdef DEBUGBUILD
+  {
+    char *tty = curlx_getenv("CURL_ISATTY");
+    if(tty) {
+      isatty = TRUE;
+      curl_free(tty);
+    }
+  }
+
  if(config->include_headers) {
-    if(sz * nmemb > (size_t)CURL_MAX_HTTP_HEADER) {
+    if(bytes > (size_t)CURL_MAX_HTTP_HEADER) {
      warnf(config->global, "Header data size exceeds single call write "
            "limit!\n");
      return failure;
    }
  }
  else {
-    if(sz * nmemb > (size_t)CURL_MAX_WRITE_SIZE) {
+    if(bytes > (size_t)CURL_MAX_WRITE_SIZE) {
      warnf(config->global, "Data size exceeds single call write limit!\n");
      return failure;
    }
@@ -137,11 +147,22 @@ size_t tool_write_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
  if(!outs->stream && !tool_create_output_file(outs))
    return failure;

+  if(isatty && (outs->bytes < 2000) && !config->terminal_binary_ok) {
+    /* binary output to terminal? */
+    if(memchr(buffer, 0, bytes)) {
+      warnf(config->global, "Binary output can mess up your terminal. "
+            "Use \"--output -\" to tell curl to output it to your terminal "
+            "anyway, or consider \"--output <FILE>\" to save to a file.\n");
+      config->synthetic_error = ERR_BINARY_TERMINAL;
+      return failure;
+    }
+  }
+
  rc = fwrite(buffer, sz, nmemb, outs->stream);

-  if((sz * nmemb) == rc)
+  if(bytes == rc)
    /* we added this amount of data to the output */
-    outs->bytes += (sz * nmemb);
+    outs->bytes += bytes;

  if(config->readbusy) {
    config->readbusy = FALSE;
diff --git a/src/tool_cfgable.h b/src/tool_cfgable.h
@@ -27,6 +27,12 @@

 #include "tool_metalink.h"

+typedef enum {
+  ERR_NONE,
+  ERR_BINARY_TERMINAL = 1, /* binary to terminal detected */
+  ERR_LAST
+} curl_error;
+
 struct GlobalConfig;

 struct OperationConfig {
@@ -141,6 +147,7 @@ struct OperationConfig {
  bool insecure_ok;         /* set TRUE to allow insecure SSL connects */
  bool proxy_insecure_ok;   /* set TRUE to allow insecure SSL connects
                               for proxy */
+  bool terminal_binary_ok;
  bool verifystatus;
  bool create_dirs;
  bool ftp_create_dirs;
@@ -236,6 +243,8 @@ struct OperationConfig {
  double expect100timeout;
  bool suppress_connect_headers;  /* suppress proxy CONNECT response headers
                                     from user callbacks */
+  curl_error synthetic_error;     /* if non-zero, it overrides any libcurl
+                                     error */
  struct GlobalConfig *global;
  struct OperationConfig *prev;
  struct OperationConfig *next;   /* Always last in the struct */
diff --git a/src/tool_getparam.c b/src/tool_getparam.c
@@ -1554,7 +1554,7 @@ ParameterError getparameter(const char *flag, /* f or -long-flag */
        config->proxy_insecure_ok = toggle;
        break;

-      case '9':
+      case '9': /* --proxy-tlsv1 */
        /* TLS version 1 for proxy */
        config->proxy_ssl_version = CURL_SSLVERSION_TLSv1;
        break;
diff --git a/src/tool_help.c b/src/tool_help.c
@@ -252,7 +252,7 @@ static const struct helptxt helptext[] = {
   "Use HTTP NTLM authentication"},
  {"    --ntlm-wb",
   "Use HTTP NTLM authentication with winbind"},
-  {"    --oauth2-bearer",
+  {"    --oauth2-bearer <token>",
   "OAuth 2 Bearer Token"},
  {"-o, --output <file>",
   "Write to file instead of stdout"},
diff --git a/src/tool_main.c b/src/tool_main.c
@@ -5,7 +5,7 @@
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
- * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
diff --git a/src/tool_operate.c b/src/tool_operate.c
@@ -862,6 +862,9 @@ static CURLcode operate_do(struct GlobalConfig *global,
          set_binmode(stdout);
        }

+        /* explicitly passed to stdout means okaying binary gunk */
+        config->terminal_binary_ok = (outfile && !strcmp(outfile, "-"));
+
        if(!config->tcp_nodelay)
          my_setopt(curl, CURLOPT_TCP_NODELAY, 0L);

@@ -1764,7 +1767,10 @@ static CURLcode operate_do(struct GlobalConfig *global,
        }
        else
 #endif
-        if(result && global->showerror) {
+        if(config->synthetic_error) {
+          ;
+        }
+        else if(result && global->showerror) {
          fprintf(global->errors, "curl: (%d) %s\n", result, (errorbuffer[0]) ?
                  errorbuffer : curl_easy_strerror(result));
          if(result == CURLE_SSL_CACERT)
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
@@ -151,7 +151,7 @@ test1396 test1397 test1398 \
 test1400 test1401 test1402 test1403 test1404 test1405 test1406 test1407 \
 test1408 test1409 test1410 test1411 test1412 test1413 test1414 test1415 \
 test1416 test1417 test1418 test1419 test1420 test1421 test1422 test1423 \
-test1424 \
+test1424 test1425 test1426 \
 test1428 test1429 test1430 test1431 test1432 test1433 test1434 test1435 \
 test1436 test1437 test1438 test1439 test1440 test1441 test1442 test1443 \
 test1444 test1445 test1446 \
diff --git a/tests/data/test1425 b/tests/data/test1425
diff --git a/tests/data/test1426 b/tests/data/test1426