FreeBSD Manual Pages
CURLOPT_DEBUGFUNCTION(3) Library Functions Manual CURLOPT_DEBUGFUNCTION(3) NAME CURLOPT_DEBUGFUNCTION - debug callback SYNOPSIS #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 *clientp); 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 is not null-terminated, but is exactly of the size as told by the size argument. WARNING: this callback may receive sensitive contents from headers and data, including information sent as CURLINFO_TEXT. The clientp 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 the unprocessed protocol data received from the peer. Even if the data is encoded or compressed, it is not provided de- coded nor decompressed to this callback. If you need the data in de- coded and decompressed form, use CURLOPT_WRITEFUNCTION(3). 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. WARNING: This callback may be called with the curl handle set to an inter- nal handle. (Added in 8.4.0) If you need to distinguish your curl handle from internal handles then set CURLOPT_PRIVATE(3) on your handle. DEFAULT NULL PROTOCOLS This functionality affects all supported protocols 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, %lu bytes (0x%lx)\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 *clientp) { const char *text; (void)handle; (void)clientp; switch(type) { case CURLINFO_TEXT: fputs("== Info: ", stderr); fwrite(data, size, 1, stderr); return 0; 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 result; 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/"); result = curl_easy_perform(curl); /* Check for errors */ if(result != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(result)); /* always cleanup */ curl_easy_cleanup(curl); } return 0; } AVAILABILITY Added in curl 7.9.6 RETURN VALUE curl_easy_setopt(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3). SEE ALSO CURLINFO_CONN_ID(3), CURLINFO_XFER_ID(3), CURLOPT_DEBUGDATA(3), CUR- LOPT_VERBOSE(3), curl_global_trace(3) libcurl 2026-06-11 CURLOPT_DEBUGFUNCTION(3)
NAME | SYNOPSIS | DESCRIPTION | DEFAULT | PROTOCOLS | EXAMPLE | AVAILABILITY | RETURN VALUE | SEE ALSO
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=CURLOPT_DEBUGFUNCTION&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>