How to null the output of smtp - c++

Question

I am using the following code for smtp:
When it invokes sendEmail, the output will display in the terminal. How can I send it to dev/null or not output it? Running in background doesn't help.
Partial Output:
* About to connect() to smtp.gmail.com port 587 (#0)
* Trying 173.194.79.109... * connected
< 220 mx.google.com ESMTP nv6sm10641402pbc.42
> EHLO ubuntu
< 250-mx.google.com at your service, [222.164.82.97]
< 250-SIZE 35882577
< 250-8BITMIME
< 250-STARTTLS
< 250 ENHANCEDSTATUSCODES
> STARTTLS
< 220 2.0.0 Ready to start TLS
* successfully set certificate verify locations:
* CAfile: none
Code:
#include <stdio.h>
#include <string>
#include <cstring>
#include <curl/curl.h>
using namespace std;
/* This is a simple example showing how to send mail using libcurl's SMTP
* capabilities. It builds on the simplesmtp.c example, adding some
* authentication and transport security.
*/
#define FROM "<asktheprogramer2#gmail.com>"
#define CC "<asktheprogramer2#gmail.com>"
string ToAddress,strSubject, strMessage;
struct upload_status {
int lines_read;
};
static size_t payload_source(void *ptr, size_t size, size_t nmemb, void *userp)
{
const char *payload_text[]={ToAddress.c_str(),"From: " FROM "\n","Cc: " CC "\n",strSubject.c_str(),"\n", /* empty line to divide headers from body, see RFC5322 */
strMessage.c_str(),NULL};
struct upload_status *upload_ctx = (struct upload_status *)userp;
const char *data;
if ((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
return 0;
}
data = payload_text[upload_ctx->lines_read];
if (data) {
size_t len = strlen(data);
memcpy(ptr, data, len);
upload_ctx->lines_read ++;
return len;
}
return 0;
}
void sendMail(string strRecipent, string strAubject, string strBessage){
ToAddress="To: ";
ToAddress+=strRecipent;
ToAddress+="\n";
strSubject="Subject: ";
strSubject+=strAubject;
strSubject+="\n";
strMessage=strBessage;
CURL *curl;
CURLcode res;
struct curl_slist *recipients = NULL;
struct upload_status upload_ctx;
upload_ctx.lines_read = 0;
curl = curl_easy_init();
if (curl) {
/* This is the URL for your mailserver. Note the use of port 587 here,
* instead of the normal SMTP port (25). Port 587 is commonly used for
* secure mail submission (see RFC4403), but you should use whatever
* matches your server configuration. */
curl_easy_setopt(curl, CURLOPT_URL, "smtp://smtp.gmail.com:500");
/* In this example, we'll start with a plain text connection, and upgrade
* to Transport Layer Security (TLS) using the STARTTLS command. Be careful
* of using CURLUSESSL_TRY here, because if TLS upgrade fails, the transfer
* will continue anyway - see the security discussion in the libcurl
* tutorial for more details. */
curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
/* If your server doesn't have a valid certificate, then you can disable
* part of the Transport Layer Security protection by setting the
* CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST options to 0 (false).
* curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
* curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
* That is, in general, a bad idea. It is still better than sending your
* authentication details in plain text though.
* Instead, you should get the issuer certificate (or the host certificate
* if the certificate is self-signed) and add it to the set of certificates
* that are known to libcurl using CURLOPT_CAINFO and/or CURLOPT_CAPATH. See
* docs/SSLCERTS for more information.
*/
//curl_easy_setopt(curl, CURLOPT_CAINFO, "/path/to/certificate.pem");
/* A common reason for requiring transport security is to protect
* authentication details (user names and passwords) from being "snooped"
* on the network. Here is how the user name and password are provided: */
curl_easy_setopt(curl, CURLOPT_USERNAME, "sim.dssprojects#gmail.com");
curl_easy_setopt(curl, CURLOPT_PASSWORD, "SIMpassword");
/* value for envelope reverse-path */
curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);
/* Add two recipients, in this particular case they correspond to the
* To: and Cc: addressees in the header, but they could be any kind of
* recipient. */
recipients = curl_slist_append(recipients, strRecipent.c_str());
recipients = curl_slist_append(recipients, CC);
curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
/* In this case, we're using a callback function to specify the data. You
* could just use the CURLOPT_READDATA option to specify a FILE pointer to
* read from.
*/
curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
/* Since the traffic will be encrypted, it is very useful to turn on debug
* information within libcurl to see what is happening during the transfer.
*/
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
/* send the message (including headers) */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
/* free the list of recipients and clean up */
curl_slist_free_all(recipients);
curl_easy_cleanup(curl);
}
}
int main(void)
{
int pid = fork();
if (pid == 0)
{
for(int i=0;i<2;i++)
{
sleep(10);
sendMail("<asktheprogramer#gmail.com>","ABE Reminder","You have an appt in 15 mins");
}
return 0;
}
else
{
sleep(30);
}
return 0;
}

Answer 1

A possibility would be to redirect the standard output and standard error. I am unsure if there is an equivalent mechanism for achieving this via C++ streams but you could use freopen():
freopen("stdout.txt", "w", stdout);
freopen("stderr.txt", "w", stderr);

Answer 2

You can redirect the output of your program when running it. Like this (assuming *nix environment):
./<yourprogram> > /dev/null
for the standard output.
./<yourprogram> &> /dev/null
for standard and error outputs.

Answer 3

Delete or comment out this line from the code:
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);