#include <curl/curl.h>

typedef enum {
 CURLINFO_TEXT = 0,
 CURLINFO_HEADER_IN, /* 1 */
 CURLINFO_HEADER_OUT, /* 2 */
 CURLINFO_DATA_IN, /* 3 */
 CURLINFO_DATA_OUT, /* 4 */
 CURLINFO_SSL_DATA_IN, /* 5 */
 CURLINFO_SSL_DATA_OUT, /* 6 */
 CURLINFO_END
} curl_infotype;

int debug_callback(CURL *handle,
 curl_infotype type,
 char *data,
 size_t size,
 void *userptr);

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DEBUGFUNCTION,
 debug_callback);
 DESCRIPTION
Pass a pointer to your callback function, which should match the prototype
shown above.

CURLOPT_DEBUGFUNCTION(3) replaces the standard debug function used when
CURLOPT_VERBOSE(3) is in effect. This callback receives debug
information, as specified in the type argument. This function must
return 0. The data pointed to by the char * passed to this function WILL
NOT be null-terminated, but will be exactly of the size as told by the
size argument.

The userptr argument is the pointer set with CURLOPT_DEBUGDATA(3).

Available curl_infotype values:
 CURLINFO_TEXT
The data is informational text.
 CURLINFO_HEADER_IN
The data is header (or header-like) data received from the peer.
 CURLINFO_HEADER_OUT
The data is header (or header-like) data sent to the peer.
 CURLINFO_DATA_IN
The data is protocol data received from the peer.
 CURLINFO_DATA_OUT
The data is protocol data sent to the peer.
 CURLINFO_SSL_DATA_OUT
The data is SSL/TLS (binary) data sent to the peer.
 CURLINFO_SSL_DATA_IN
The data is SSL/TLS (binary) data received from the peer.
 DEFAULT
NULL
 PROTOCOLS
All
 EXAMPLE
static
void dump(const char *text,
 FILE *stream, unsigned char *ptr, size_t size)
{
 size_t i;
 size_t c;
 unsigned int width=0x10;

 fprintf(stream, "%s, %10.10ld bytes (0x%8.8lx)\\n",
 text, (long)size, (long)size);

 for(i=0; i<size; i+= width) {
 fprintf(stream, "%4.4lx: ", (long)i);

 /* show hex to the left */
 for(c = 0; c < width; c++) {
 if(i+c < size)
 fprintf(stream, "%02x ", ptr[i+c]);
 else
 fputs(" ", stream);
 }

 /* show data on the right */
 for(c = 0; (c < width) && (i+c < size); c++) {
 char x = (ptr[i+c] >= 0x20 && ptr[i+c] < 0x80) ? ptr[i+c] : '.';
 fputc(x, stream);
 }

 fputc('\\n', stream); /* newline */
 }
}

static
int my_trace(CURL *handle, curl_infotype type,
 char *data, size_t size,
 void *userp)
{
 const char *text;
 (void)handle; /* prevent compiler warning */
 (void)userp;

 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_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;
 }

 dump(text, stderr, (unsigned char *)data, size);
 return 0;
}

int main(void)
{
 CURL *curl;
 CURLcode res;

 curl = curl_easy_init();
 if(curl) {
 curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, my_trace);

 /* 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;
}

 AVAILABILITY
Always
 RETURN VALUE
Returns CURLE_OK
 "SEE ALSO"
 CURLOPT_VERBOSE "(3), " CURLOPT_DEBUGDATA "(3), "