debug.c
/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 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.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. * * SPDX-License-Identifier: curl * ***************************************************************************/ /* <DESC> * Show how CURLOPT_DEBUGFUNCTION can be used. * </DESC> */ #include <stdio.h> #include <curl/curl.h> struct data { char trace_ascii; /* 1 or 0 */ }; static void dump(const char *text, FILE *stream, unsigned char *ptr, size_t size, char nohex) { size_t i; size_t c; unsigned int width = 0x10; if(nohex) /* without the hex output, we can fit more on screen */ width = 0x40; fprintf(stream, "%s, %10.10lu bytes (0x%8.8lx)\n", text, (unsigned long)size, (unsigned long)size); for(i = 0; i < size; i += width) { fprintf(stream, "%4.4lx: ", (unsigned long)i); if(!nohex) { /* hex not disabled, show it */ for(c = 0; c < width; c++) if(i + c < size) fprintf(stream, "%02x ", ptr[i + c]); else fputs(" ", stream); } for(c = 0; (c < width) && (i + c < size); c++) { /* check for 0D0A; if found, skip past and start a new line of output */ if(nohex && (i + c + 1 < size) && ptr[i + c] == 0x0D && ptr[i + c + 1] == 0x0A) { i += (c + 2 - width); break; } fprintf(stream, "%c", (ptr[i + c] >= 0x20) && (ptr[i + c] < 0x80) ? ptr[i + c] : '.'); /* check again for 0D0A, to avoid an extra \n if it's at width */ if(nohex && (i + c + 2 < size) && ptr[i + c + 1] == 0x0D && ptr[i + c + 2] == 0x0A) { i += (c + 3 - width); break; } } fputc('\n', stream); /* newline */ } fflush(stream); } static int my_trace(CURL *handle, curl_infotype type, char *data, size_t size, void *userp) { struct data *config = (struct data *)userp; const char *text; (void)handle; /* prevent compiler warning */ switch(type) { case CURLINFO_TEXT: fprintf(stderr, "== Info: %s", data); return 0; case CURLINFO_HEADER_OUT: text = "=> Send header"; break; case CURLINFO_DATA_OUT: text = "=> Send data"; break; case CURLINFO_SSL_DATA_OUT: text = "=> Send SSL data"; break; case CURLINFO_HEADER_IN: text = "<= Recv header"; break; case CURLINFO_DATA_IN: text = "<= Recv data"; break; case CURLINFO_SSL_DATA_IN: text = "<= Recv SSL data"; break; default: /* in case a new one is introduced to shock us */ return 0; } dump(text, stderr, (unsigned char *)data, size, config->trace_ascii); return 0; } int main(void) { CURL *curl; CURLcode res; struct data config; config.trace_ascii = 1; /* enable ASCII tracing */ curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, my_trace); curl_easy_setopt(curl, CURLOPT_DEBUGDATA, &config); /* the DEBUGFUNCTION has no effect until we enable VERBOSE */ curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); /* example.com is redirected, so we tell libcurl to follow redirection */ curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); res = curl_easy_perform(curl); /* Check for errors */ if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); /* always cleanup */ curl_easy_cleanup(curl); } return 0; }
Notice
This source code example is simplified and ignores return
codes and error checks to a large extent. We do this to highlight the libcurl
function calls and related options and reduce unrelated code.
A real-world application will of course properly check every return value and exit correctly at the first serious error.