Post transfer info

Remember how libcurl transfers are associated with an "easy handle"! Each transfer has such a handle and when a transfer is completed, before the handle is cleaned or reused for another transfer, it can be used to extract information from the previous operation.

Your friend for doing this is called curl_easy_getinfo() and you tell it which specific information you are interested in and it will return that to you if it can.

When you use this function, you pass in the easy handle, which information you want and a pointer to a variable to hold the answer. You must pass in a pointer to a variable of the correct type or you risk that things will go side-ways. These information values are designed to be provided after the transfer is completed.

The data you receive can be a long, a 'char ', a 'struct curl_slist ', a double or a socket.

This is how you extract the Content-Type: value from the previous HTTP transfer:

CURLcode res;
char *content_type;
res = curl_easy_getinfo(curl, CURLINFO_CONTENT_TYPE, &content_type);

If you want to extract the local port number that was used in that connection:

CURLcode res;
long port_number;
res = curl_easy_getinfo(curl, CURLINFO_LOCAL_PORT, &port_number);

Available information

Getinfo option

Type

Description

CURLINFO_ACTIVESOCKET

curl_socket_t

The session's active socket

CURLINFO_APPCONNECT_TIME

double

Time from start until SSL/SSH handshake completed.

CURLINFO_CERTINFO

struct curl_slist *

Certificate chain

CURLINFO_CONDITION_UNMET

long

Whether or not a time conditional was met

CURLINFO_CONNECT_TIME

double

Time from start until remote host or proxy completed

CURLINFO_CONTENT_LENGTH_DOWNLOAD

double

Content length from the Content-Length header

CURLINFO_CONTENT_LENGTH_UPLOAD

double

Upload size

CURLINFO_CONTENT_TYPE

char *

Content type from the Content-Type header

CURLINFO_COOKIELIST

struct curl_slist *

List of all known cookies

CURLINFO_EFFECTIVE_URL

char *

Last used URL

CURLINFO_FILETIME

long

Remote time of the retrieved document

CURLINFO_FTP_ENTRY_PATH

char *

The entry path after logging in to an FTP server

CURLINFO_HEADER_SIZE

long

Number of bytes of all headers received

CURLINFO_HTTPAUTH_AVAIL

long

Available HTTP authentication methods (bitmask)

CURLINFO_HTTP_CONNECTCODE

long

Last proxy CONNECT response code

CURLINFO_HTTP_VERSION

long

The http version used in the connection

CURLINFO_LASTSOCKET

long

Last socket used

CURLINFO_LOCAL_IP

char *

Local-end IP address of last connection

CURLINFO_LOCAL_PORT

long

Local-end port of last connection

CURLINFO_NAMELOOKUP_TIME

double

Time from start until name resolving completed

CURLINFO_NUM_CONNECTS

long

Number of new successful connections used for previous transfer

CURLINFO_OS_ERRNO

long

The errno from the last failure to connect

CURLINFO_PRETRANSFER_TIME

double

Time from start until just before the transfer begins

CURLINFO_PRIMARY_IP

char *

IP address of the last connection

CURLINFO_PRIMARY_PORT

long

Port of the last connection

CURLINFO_PRIVATE

char *

User's private data pointer

CURLINFO_PROTOCOL

long

The protocol used for the connection

CURLINFO_PROXYAUTH_AVAIL

long

Available HTTP proxy authentication methods

CURLINFO_PROXY_SSL_VERIFYRESULT

long

Proxy certificate verification result

CURLINFO_REDIRECT_COUNT

long

Total number of redirects that were followed

CURLINFO_REDIRECT_TIME

double

Time taken for all redirect steps before the final transfer

CURLINFO_REDIRECT_URL

char *

URL a redirect would take you to, had you enabled redirects

CURLINFO_REQUEST_SIZE

long

Number of bytes sent in the issued HTTP requests

CURLINFO_RESPONSE_CODE

long

Last received response code

CURLINFO_RTSP_CLIENT_CSEQ

long

RTSP CSeq that will next be used

CURLINFO_RTSP_CSEQ_RECV

long

RTSP CSeq last received

CURLINFO_RTSP_SERVER_CSEQ

long

RTSP CSeq that will next be expected

CURLINFO_RTSP_SESSION_ID

char *

RTSP session ID

CURLINFO_SCHEME

char *

The scheme used for the connection

CURLINFO_SIZE_DOWNLOAD

double

Number of bytes downloaded

CURLINFO_SIZE_UPLOAD

double

Number of bytes uploaded

CURLINFO_SPEED_DOWNLOAD

double

Average download speed

CURLINFO_SPEED_UPLOAD

double

Average upload speed

CURLINFO_SSL_ENGINES

struct curl_slist *

A list of OpenSSL crypto engines

CURLINFO_SSL_VERIFYRESULT

long

Certificate verification result

CURLINFO_STARTTRANSFER_TIME

double

Time from start until just when the first byte is received

CURLINFO_TLS_SESSION

struct curl_slist *

TLS session info that can be used for further processing. (Deprecated option, use CURLINFO_TLS_SSL_PTR instead!)

CURLINFO_TLS_SSL_PTR

struct curl_slist *

TLS session info that can be used for further processing

CURLINFO_TOTAL_TIME

double

Total time of previous transfer