writeout: support to generate JSON output

This commit adds support to generate JSON via the writeout feature:

    -w "%{json}"

It leverages the existing infrastructure as much as possible. Thus,
generating the JSON on STDERR is possible by:

    -w "%{stderr}%{json}"

This implements a variant of https://github.com/curl/curl/wiki/JSON#--write-out-json.

docs/cmdline-opts/write-out.d

@@ -50,6 +50,9 @@ curl CONNECT request. (Added in 7.12.4)
 .B http_version
 The http version that was effectively used. (Added in 7.50.0)
 .TP
+.B json
+A JSON object with all available keys.
+.TP
 .B local_ip
 The IP address of the local end of the most recently done connection - can be
 either IPv4 or IPv6 (Added in 7.29.0)

packages/Symbian/group/curl.mmp

@@ -45,6 +45,7 @@ SOURCE \
     tool_vms.c \
     tool_writeenv.c \
     tool_writeout.c \
+    tool_writeout_json.c \
     tool_xattr.c
 
 SOURCEPATH  ../../../lib

src/Makefile.inc

@@ -62,6 +62,7 @@ CURL_CFILES = \
   tool_util.c \
   tool_vms.c \
   tool_writeout.c \
+  tool_writeout_json.c \
   tool_xattr.c
 
 CURL_HFILES = \
@@ -107,6 +108,7 @@ CURL_HFILES = \
   tool_version.h \
   tool_vms.h \
   tool_writeout.h \
+  tool_writeout_json.h \
   tool_xattr.h
 
 CURL_RCFILES = curl.rc

src/tool_writeout.c

@@ -25,6 +25,7 @@
 #include "curlx.h"
 #include "tool_cfgable.h"
 #include "tool_writeout.h"
+#include "tool_writeout_json.h"
 
 #include "memdebug.h" /* keep this as LAST include */
 
@@ -62,6 +63,7 @@ typedef enum {
   VAR_SCHEME,
   VAR_STDOUT,
   VAR_STDERR,
+  VAR_JSON,
   VAR_NUM_OF_VARS /* must be the last */
 } replaceid;
 
@@ -105,6 +107,7 @@ static const struct variable replacements[]={
   {"scheme", VAR_SCHEME},
   {"stdout", VAR_STDOUT},
   {"stderr", VAR_STDERR},
+  {"json", VAR_JSON},
   {NULL, VAR_NONE}
 };
 
@@ -334,6 +337,8 @@ void ourWriteOut(CURL *curl, struct OutStruct *outs, const char *writeinfo)
               case VAR_STDERR:
                 stream = stderr;
                 break;
+              case VAR_JSON:
+                ourWriteOutJSON(curl, outs, stream);
               default:
                 break;
               }

src/tool_writeout_json.c

@@ -0,0 +1,223 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2020, 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
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "tool_setup.h"
+
+#define ENABLE_CURLX_PRINTF
+
+/* use our own printf() functions */
+#include "curlx.h"
+#include "tool_cfgable.h"
+#include "tool_writeout_json.h"
+
+
+typedef enum {
+  JSON_NONE,
+  JSON_STRING,
+  JSON_LONG,
+  JSON_TIME,
+  JSON_VERSION,
+  JSON_FILENAME
+} jsontype;
+
+struct mapping {
+  const char *key;
+  jsontype type;
+  CURLINFO cinfo;
+};
+
+static const struct mapping mappings[]={
+  {"url_effective", JSON_STRING, CURLINFO_EFFECTIVE_URL},
+  {"http_code", JSON_LONG, CURLINFO_RESPONSE_CODE},
+  {"response_code", JSON_LONG, CURLINFO_RESPONSE_CODE},
+  {"http_connect", JSON_LONG, CURLINFO_HTTP_CONNECTCODE},
+  {"time_total", JSON_TIME, CURLINFO_TOTAL_TIME_T},
+  {"time_namelookup", JSON_TIME, CURLINFO_NAMELOOKUP_TIME_T},
+  {"time_connect", JSON_TIME, CURLINFO_CONNECT_TIME_T},
+  {"time_appconnect", JSON_TIME, CURLINFO_APPCONNECT_TIME_T},
+  {"time_pretransfer", JSON_TIME, CURLINFO_PRETRANSFER_TIME_T},
+  {"time_starttransfer", JSON_TIME, CURLINFO_STARTTRANSFER_TIME_T},
+  {"size_header", JSON_LONG, CURLINFO_HEADER_SIZE},
+  {"size_request", JSON_LONG, CURLINFO_REQUEST_SIZE},
+  {"size_download", JSON_LONG, CURLINFO_SIZE_DOWNLOAD_T},
+  {"size_upload", JSON_LONG, CURLINFO_SIZE_UPLOAD_T},
+  {"speed_download", JSON_TIME, CURLINFO_SPEED_DOWNLOAD_T},
+  {"speed_upload", JSON_TIME, CURLINFO_SPEED_UPLOAD_T},
+  {"content_type", JSON_STRING, CURLINFO_CONTENT_TYPE},
+  {"num_connects", JSON_LONG, CURLINFO_NUM_CONNECTS},
+  {"time_redirect", JSON_TIME, CURLINFO_REDIRECT_TIME_T},
+  {"num_redirects", JSON_LONG, CURLINFO_REDIRECT_COUNT},
+  {"ftp_entry_path", JSON_STRING, CURLINFO_FTP_ENTRY_PATH},
+  {"redirect_url", JSON_STRING, CURLINFO_REDIRECT_URL},
+  {"ssl_verify_result", JSON_LONG, CURLINFO_SSL_VERIFYRESULT},
+  {"proxy_ssl_verify_result", JSON_LONG, CURLINFO_PROXY_SSL_VERIFYRESULT},
+  {"filename_effective", JSON_FILENAME, CURLINFO_NONE},
+  {"remote_ip", JSON_STRING, CURLINFO_PRIMARY_IP},
+  {"remote_port", JSON_LONG, CURLINFO_PRIMARY_PORT},
+  {"local_ip", JSON_STRING, CURLINFO_LOCAL_IP},
+  {"local_port", JSON_LONG, CURLINFO_LOCAL_PORT},
+  {"http_version", JSON_VERSION, CURLINFO_HTTP_VERSION},
+  {"scheme", JSON_STRING, CURLINFO_SCHEME},
+  {NULL, JSON_NONE, CURLINFO_NONE}
+};
+
+static const char *http_version[] = {
+  "0",   /* CURL_HTTP_VERSION_NONE */
+  "1",   /* CURL_HTTP_VERSION_1_0 */
+  "1.1", /* CURL_HTTP_VERSION_1_1 */
+  "2"    /* CURL_HTTP_VERSION_2 */
+  "3"    /* CURL_HTTP_VERSION_3 */
+};
+
+static void json_escape(FILE *stream, const char *in)
+{
+  const char *i = in;
+  const char *in_end = in + strlen(in);
+
+  for(; i < in_end; i++) {
+    switch(*i) {
+    case '\\':
+      fputs("\\\\", stream);
+      break;
+    case '\"':
+      fputs("\\\"", stream);
+      break;
+    case '\b':
+      fputs("\\b", stream);
+      break;
+    case '\f':
+      fputs("\\f", stream);
+      break;
+    case '\n':
+      fputs("\\n", stream);
+      break;
+    case '\r':
+      fputs("\\r", stream);
+      break;
+    case '\t':
+      fputs("\\t", stream);
+      break;
+    default:
+      if (*i < 32) {
+        fprintf(stream, "u%04x", *i);
+      }
+      else {
+        fputc(*i, stream);
+      }
+      break;
+    };
+  }
+}
+
+static int write_field_time(FILE *stream, CURL *curl, const char *key, CURLINFO cinfo)
+{
+  long val = 0;
+  if(CURLE_OK == curl_easy_getinfo(curl, cinfo, &val)) {
+    long s = val / 1000000l;
+    long ms = val % 1000000l;
+    fprintf(stream, "\"%s\":%ld.%06ld,", key, s, ms);
+    return 1;
+  }
+  return 0;
+}
+
+static int write_field_string(FILE *stream, CURL *curl, const char *key, CURLINFO cinfo)
+{
+  char *valp = NULL;
+  if((CURLE_OK == curl_easy_getinfo(curl, cinfo, &valp)) && valp) {
+    fprintf(stream, "\"%s\":\"", key);
+    json_escape(stream, valp);
+    fprintf(stream, "\"");
+    return 1;
+  }
+  return 0;
+}
+
+static int write_field_long(FILE *stream, CURL *curl, const char *key, CURLINFO cinfo)
+{
+  long val = 0;
+  if(CURLE_OK == curl_easy_getinfo(curl, cinfo, &val)) {
+    fprintf(stream, "\"%s\":%ld", key, val);
+    return 1;
+  }
+  return 0;
+}
+
+static int write_field_filename(FILE *stream, const char* key, const char *filename)
+{
+  if(filename) {
+    fprintf(stream, "\"%s\":\"", key);
+    json_escape(stream, filename);
+    fprintf(stream, "\"");
+  }
+  else {
+    fprintf(stream, "\"%s\":null", key);
+  }
+  return 1;
+}
+
+static int write_field_version(FILE *stream, CURL *curl, const char *key, CURLINFO cinfo)
+{
+  long version = 0;
+  if(CURLE_OK == curl_easy_getinfo(curl, cinfo, &version) &&
+     (version >= 0) &&
+     (version < (long)(sizeof(http_version)/sizeof(char *)))) {
+    fprintf(stream, "\"%s\":\"%s\"", key, http_version[version]);
+    return 1;
+  }
+  return 0;
+}
+
+void ourWriteOutJSON(CURL *curl, struct OutStruct *outs, FILE *stream)
+{
+  int i;
+
+  fputs("{", stream);
+  for(i = 0; mappings[i].key != NULL; i++) {
+    const char *key = mappings[i].key;
+    CURLINFO cinfo = mappings[i].cinfo;
+    int ok = 0;
+    switch(mappings[i].type) {
+    case JSON_STRING:
+      ok = write_field_string(stream, curl, key, cinfo);
+      break;
+    case JSON_LONG:
+      ok = write_field_long(stream, curl, key, cinfo);
+      break;
+    case JSON_TIME:
+      ok = write_field_time(stream, curl, key, cinfo);
+      break;
+    case JSON_FILENAME:
+      ok = write_field_filename(stream, outs->filename, key);
+      break;
+    case JSON_VERSION:
+      ok = write_field_version(stream, curl, key, cinfo);
+      break;
+    default:
+      break;
+    }
+
+    if(ok) {
+      fputs(",", stream);
+    }
+  }
+  fprintf(stream, "\"curl_version\":\"%s\"}", curl_version());
+}

src/tool_writeout_json.h

@@ -0,0 +1,28 @@
+#ifndef HEADER_CURL_TOOL_WRITEOUT_JSON_H
+#define HEADER_CURL_TOOL_WRITEOUT_JSON_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2020, 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
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "tool_setup.h"
+
+void ourWriteOutJSON(CURL *curl, struct OutStruct *outs, FILE *stream);
+
+#endif /* HEADER_CURL_TOOL_WRITEOUT_H */