debug.c is a fresh new example showing how to use the DEBUGFUNCTION to get

lots of fine info from a transfer

docs/examples/Makefile.am

@@ -9,7 +9,7 @@ EXTRA_DIST = README curlgtk.c sepheaders.c simple.c postit2.c		\
  ftpupload.c httpput.c simplessl.c ftpgetresp.c http-post.c		\
  post-callback.c multi-app.c multi-double.c multi-single.c		\
  multi-post.c fopen.c simplepost.c makefile.dj curlx.c https.c		\
- multi-debugcallback.c fileupload.c getinfo.c ftp3rdparty.c
+ multi-debugcallback.c fileupload.c getinfo.c ftp3rdparty.c debug.c
 
 all:
 	@echo "done"

docs/examples/debug.c

@@ -0,0 +1,128 @@
+/*****************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * $Id$
+ */
+
+#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, %zd bytes (0x%zx)\n", text, size, size);
+
+  for(i=0; i<size; i+= width) {
+
+    fprintf(stream, "%04zx: ", 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,
+             unsigned 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);
+  default: /* in case a new one is introduced to shock us */
+    return 0;
+
+  case CURLINFO_HEADER_OUT:
+    text = "=> Send header";
+    break;
+  case CURLINFO_DATA_OUT:
+    text = "=> Send 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;
+  case CURLINFO_SSL_DATA_OUT:
+    text = "<= Send SSL data";
+    break;
+  }
+
+  dump(text, stderr, 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, 1);
+
+    curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
+    res = curl_easy_perform(curl);
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+  }
+  return 0;
+}