NAME

Simple Mail Transfer Protocol Services – Smtp

SYNOPSIS

#include <smtp.h>

int smtp_accounts_setup(struct smtp_account_config * smtp_account_config, struct smtp_timout* timeout);

iint smtp_send_mail(struct smtp_mail_attribute * smtp_mail_attribute, int sock, int ssl_flag, SSL *ssl);

DESCRIPTION

Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (e-mail) transmission across Internet Protocol (IP) networks. SMTP connections can be secured by SSL/TLS. SMTP component also may be used together with DNS, DHCP, SNTP and File System components.

SPECIFIC OPTIONS (Compile time)

USER EVENTS FUNCTIONS

Initialization of client.

	int smtp_accounts_setup(struct smtp_account_config * smtp_account_config, struct smtp_timout* _smtp_timout);

Client setting:

	struct smtp_account_config{
		char*	hostname;	
		char*	client_mail;	
		char*	client_login;
		char* 	client_pass;
		char* 	smtp_server;	
	};
	

hostname 	- name of host
client_mail 	- email address of host
client_login	- login of host for authentication
client_pass	- password of host for authentication
smtp_server	- name server for send emails

Time waiting for a response from mail server :

	struct smtp_timout {
		int connect;
		int mail;
		int rcpt; 
		int data_start
		int data_block;
		int data_end;
	};
	
connect		- time wating answer from server on connect
mail		- time wating answer from server on command "MAIL FROM"
rcpt		- time wating answer from server on command "RCPT TO"
data_start	- time wating answer from server on command "DATA"
data_block	- time wating answer from server on send conntent mail
data_end	- time wating answer from server on command "QUIT"

If user didn’t specify timeout value, then default “#define DEF_TIOUT 1500” value will be used.

Function send mails:

	int smtp_send_mail(struct smtp_mail_attribute * smtp_mail_attribute, int sock, int ssl_flag, SSL *ssl);

Options for sending emails:

	struct smtp_mail_attribute{
  		char* data;
		int cnt_address;
		char* address_to_send[10];
		char* subject;
	};
	
data		- contents of the emails
cnt_address	- number of address
address_to_send	- addresses of emails 
subject		- subject of emails


ssl_flag	- enable/disable (1/0) use ssl/tls
ssl		- ssl object

EXAMPLE

static struct smtp_account_config	smtp_account_config;
static struct smtp_mail_attribute	smtp_mail_attribute;
static struct smtp_timout		smtp_timeout;

...

{
	int _port;
	int sock_out, errval;
	struct sockaddr_in server;
	char ipstr[INET6_ADDRSTRLEN];

	int ssl_flag; 
	int result;

	SSL *ssl = NULL;

...

	ssl_flag = ENABLE_SSLTLS;

...

	xprintf("Start smtp client\n");

	/*
	 * Set configuration smtp client
	 *
	 */

	//host name
	smtp_account_config.hostname = "hello.org";

	// smtp server
	smtp_account_config.smtp_server =""; //enter smtp server for example: "smtp.gmail.com"

	//port server
	if(ssl_flag == ENABLE_SSLTLS)	
		_port = 465;
	else
		_port = 25;

	// our mail
	smtp_account_config.client_mail = "";//   enter your mail for example:"test_example@gmail.com"


	//login
	smtp_account_config.client_login = ""; // enter your login  for example:"test_example"


	//password
	smtp_account_config.client_pass = ""; // enter your password  for example:"1111"

	//subject
	smtp_mail_attribute.subject = "test";

	//data mail
	smtp_mail_attribute.data = "this is my mail";

	//count of address
	smtp_mail_attribute.cnt_address = 2; //count of mail address, for example set 2 if you send mail on two address

	//destination mail
	smtp_mail_attribute.address_to_send[0] = ""; // enter destination mail first address
	smtp_mail_attribute.address_to_send[1] = ""; // enter destination mail second address


	//set timeout smtp protocol	
	smtp_timeout.connect = 25;
	smtp_timeout.mail = 25;
	smtp_timeout.rcpt = 25;
	smtp_timeout.data_start = 25;
	smtp_timeout.data_block = 25;
	smtp_timeout.data_end = 25;

...

	smtp_accounts_setup(&smtp_account_config, &smtp_timeout);

...

	server.sin_family = AF_INET;
	server.sin_addr.s_addr = inet_addr(ipstr);
	server.sin_port = htons(_port); /* SMTP PORT */

	// Get a socket for the connection
	sock_out = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);	

...

#if _SMTP_USE_SSL > 0
	if (ssl_flag){
		result = smtp_send_mail(&smtp_mail_attribute, sock_out,  ssl_flag, ssl);
	}
#endif
	if (ssl_flag == 0){
		xprintf("without ssl\n");
		result = smtp_send_mail(&smtp_mail_attribute, sock_out,  ssl_flag, NULL);
	}

	if (result){
		xprintf("Smtp errors: %d (see smtp.h)\n", result);
	}


#if _SMTP_USE_SSL > 0
	if (ssl_flag){
		SSL_shutdown(ssl);
		SSL_free(ssl);
	}
#endif 
	close(sock_out);		

...

}

NOTES

There is a demo available for the Unison and DSPnano SMTP Client which can be found in installdir/demos.

SEE ALSO

IPv4 only server, IPv4/IPv6 server, DNS Client, SNTP Client, Multimedia File Server, FAT File System