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protocol-smtp.c
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protocol-smtp.c
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#include <stdlib.h>
#include <string.h>
#include <bglibs/systime.h>
#include "mailfront.h"
#include <bglibs/iobuf.h>
#include <bglibs/msg.h>
extern struct protocol protocol;
static str line = {0,0,0};
static str domain_name = {0,0,0};
static unsigned long maxnotimpl = 0;
static str str_welcome;
static str cmd;
static str arg;
static str addr;
static str params;
static str init_capabilities;
static RESPONSE(no_mail, 503, "5.5.1 You must send MAIL FROM: first");
static RESPONSE(vrfy, 252, "2.5.2 Send some mail, I'll try my best.");
static RESPONSE(help, 214, "2.0.0 Help not available.");
static RESPONSE(no_rcpt, 503, "5.5.1 You must send RCPT TO: first");
static RESPONSE(data_ok, 354, "End your message with a period on a line by itself.");
static RESPONSE(ok, 250, "2.3.0 OK");
static RESPONSE(unimp, 500, "5.5.1 Not implemented.");
static RESPONSE(badaddr, 501, "5.5.2 Syntax error in address parameter.");
static RESPONSE(needsparam, 501, "5.5.2 Syntax error, command requires a parameter.");
static RESPONSE(noparam, 501, "5.5.2 Syntax error, no parameters allowed.");
static RESPONSE(toomanyunimp, 503, "5.5.0 Too many unimplemented commands.\n5.5.0 Closing connection.");
static RESPONSE(goodbye, 221, "2.0.0 Good bye.");
static int saw_mail = 0;
static int saw_rcpt = 0;
static const response* parse_addr_arg(void)
{
unsigned i;
char term;
int quoted;
if (!str_truncate(&addr, 0)) return &resp_oom;
if (!str_truncate(¶ms, 0)) return &resp_oom;
addr.len = 0;
if ((i = str_findfirst(&arg, LBRACE) + 1) != 0)
term = RBRACE;
else {
term = SPACE;
if ((i = str_findfirst(&arg, COLON) + 1) == 0)
if ((i = str_findfirst(&arg, SPACE) + 1) == 0)
return &resp_badaddr;
while (i < arg.len && arg.s[i] == SPACE)
++i;
}
for (quoted = 0; i < arg.len && (quoted || arg.s[i] != term); ++i) {
switch (arg.s[i]) {
case QUOTE:
quoted = !quoted;
break;
case ESCAPE:
++i;
/* fall through */
default:
if (!str_catc(&addr, arg.s[i])) return &resp_oom;
}
}
++i;
if (i > arg.len) return &resp_badaddr;
while (i < arg.len && arg.s[i] == SPACE) ++i;
if (!str_copyb(¶ms, arg.s+i, arg.len-i)) return &resp_oom;
str_subst(¶ms, ' ', 0);
/* strip source routing */
if (addr.s[0] == AT
&& (i = str_findfirst(&addr, COLON) + 1) != 0)
str_lcut(&addr, i);
return 0;
}
static int QUIT(void)
{
respond(&resp_goodbye);
exit(0);
return 0;
}
static int HELP(void)
{
return respond(&resp_help);
}
static int HELO(void)
{
const response* resp;
if (response_ok(resp = handle_reset()))
resp = handle_helo(&arg, &line);
return (resp != 0) ? respond(resp)
: respond_line(250, 1, domain_name.s, domain_name.len);
}
static int EHLO(void)
{
const response* resp;
protocol.name = "ESMTP";
line.len = 0;
if (!response_ok(resp = handle_reset())
|| !response_ok(resp = handle_helo(&arg, &line)))
return respond(resp);
if (!str_cat(&line, &init_capabilities)) {
respond(&resp_oom);
return 0;
}
if (!respond_line(250, 0, domain_name.s, domain_name.len)) return 0;
return respond_multiline(250, 1, line.s);
}
static void do_reset(void)
{
const response* resp;
if (!response_ok(resp = handle_reset())) {
respond(resp);
exit(0);
}
saw_rcpt = 0;
saw_mail = 0;
}
// FIXME: if rules_reset fails, exit
static int MAIL(void)
{
const response* resp;
msg2("MAIL ", arg.s);
do_reset();
if ((resp = parse_addr_arg()) == 0) {
if ((resp = handle_sender(&addr, ¶ms)) == 0)
resp = &resp_accepted_sender;
if (number_ok(resp)) {
saw_mail = 1;
}
}
return respond(resp);
}
static int RCPT(void)
{
const response* resp;
msg2("RCPT ", arg.s);
if (!saw_mail) return respond(&resp_no_mail);
if ((resp = parse_addr_arg()) == 0) {
if ((resp = handle_recipient(&addr, ¶ms)) == 0)
resp = &resp_accepted_recip;
if (number_ok(resp))
saw_rcpt = 1;
}
return respond(resp);
}
static int RSET(void)
{
do_reset();
return respond(&resp_ok);
}
static char data_buf[4096];
static unsigned long data_bytes;
static unsigned data_bufpos;
static void data_start(void)
{
data_bytes = data_bufpos = 0;
}
static void data_byte(char ch)
{
data_buf[data_bufpos++] = ch;
++data_bytes;
if (data_bufpos >= sizeof data_buf) {
handle_data_bytes(data_buf, data_bufpos);
data_bufpos = 0;
}
}
static void message_end(void)
{
if (data_bufpos)
handle_data_bytes(data_buf, data_bufpos);
}
static int copy_body(void)
{
int sawcr = 0; /* Was the last character a CR */
unsigned linepos = 0; /* The number of bytes since the last LF */
int sawperiod = 0; /* True if the first character was a period */
char ch;
data_start();
while (ibuf_getc(&inbuf, &ch)) {
switch (ch) {
case LF:
if (sawperiod && linepos == 0) { message_end(); return 1; }
data_byte(ch);
sawperiod = sawcr = linepos = 0;
break;
case CR:
if (sawcr) { data_byte(CR); ++linepos; }
sawcr = 1;
break;
default:
if (ch == PERIOD && !sawperiod && linepos == 0)
sawperiod = 1;
else {
sawperiod = 0;
if (sawcr) { data_byte(CR); ++linepos; sawcr = 0; }
data_byte(ch); ++linepos;
}
}
}
return 0;
}
static int DATA(void)
{
const response* resp;
if (!saw_mail) return respond(&resp_no_mail);
if (!saw_rcpt) return respond(&resp_no_rcpt);
if (!response_ok(resp = handle_data_start()))
return respond(resp);
if (!respond(&resp_data_ok)) return 0;
if (!copy_body()) {
do_reset();
return 0;
}
if ((resp = handle_message_end()) == 0)
resp = &resp_accepted_message;
return respond(resp);
}
static int NOOP(void)
{
return respond(&resp_ok);
}
static int VRFY(void)
{
return respond(&resp_vrfy);
}
typedef int (*dispatch_fn)(void);
struct dispatch
{
const char* cmd;
dispatch_fn fn;
};
static struct dispatch dispatch_table[] = {
{ "DATA", DATA },
{ "EHLO", EHLO },
{ "HELO", HELO },
{ "HELP", HELP },
{ "MAIL", MAIL },
{ "NOOP", NOOP },
{ "QUIT", QUIT },
{ "RCPT", RCPT },
{ "RSET", RSET },
{ "VRFY", VRFY },
{ 0, 0 }
};
static int parse_line(void)
{
unsigned i;
for (i = 0; i < line.len; i++) {
if (line.s[i] == SPACE || line.s[i] == TAB) {
unsigned j = i;
while (j < line.len &&
(line.s[j] == SPACE || line.s[j] == TAB))
++j;
return str_copyb(&cmd, line.s, i) &&
str_copyb(&arg, line.s+j, line.len-j);
}
}
return str_copy(&cmd, &line) && str_truncate(&arg, 0);
}
int smtp_dispatch(const struct command* commands)
{
static unsigned long notimpl = 0;
struct dispatch* d;
const struct command* c;
if (!parse_line()) return 1;
for (c = commands; c->name != 0; c++)
if (strcasecmp(c->name, cmd.s) == 0) {
if (c->fn_enabled == 0 || c->fn_enabled()) {
notimpl = 0;
if (arg.len == 0) {
if (c->fn_noparam == 0)
return respond(&resp_noparam);
return c->fn_noparam();
}
else {
if (c->fn_hasparam == 0)
return respond(&resp_needsparam);
return c->fn_hasparam(&arg);
}
}
}
for (d = dispatch_table; d->cmd != 0; ++d)
if (strcasecmp(d->cmd, cmd.s) == 0) {
notimpl = 0;
return d->fn();
}
msg3(cmd.s, " ", arg.s);
if (maxnotimpl > 0 && ++notimpl > maxnotimpl) {
respond(&resp_toomanyunimp);
return 0;
}
return respond(&resp_unimp);
}
static int init(void)
{
const char* tmp;
if ((tmp = getprotoenv("LOCALHOST")) == 0) tmp = UNKNOWN;
str_copys(&domain_name, tmp);
if ((tmp = getenv("SMTPGREETING")) != 0)
str_copys(&str_welcome, tmp);
else {
str_copy(&str_welcome, &domain_name);
str_cats(&str_welcome, " mailfront");
}
str_cats(&str_welcome, " ESMTP");
if ((tmp = getenv("MAXNOTIMPL")) != 0)
maxnotimpl = strtoul(tmp, 0, 10);
if (!str_cats(&init_capabilities, "8BITMIME\nENHANCEDSTATUSCODES\nPIPELINING")) {
respond(&resp_oom);
return 1;
}
return 0;
}
static int mainloop(const struct command* commands)
{
if (!respond_line(220, 1, str_welcome.s, str_welcome.len)) return 0;
while (ibuf_getstr_crlf(&inbuf, &line))
if (!smtp_dispatch(commands)) {
if (ibuf_eof(&inbuf))
msg1("Connection dropped");
if (ibuf_timedout(&inbuf))
msg1("Timed out");
return 1;
}
return 0;
}
static int smtp_respond_line(unsigned num, int final,
const char* msg, unsigned long len)
{
return obuf_putu(&outbuf, num)
&& obuf_putc(&outbuf, final ? ' ' : '-')
&& obuf_write(&outbuf, msg, len)
&& obuf_puts(&outbuf, CRLF);
}
struct protocol protocol = {
.version = PROTOCOL_VERSION,
.name = "SMTP",
.respond_line = smtp_respond_line,
.init = init,
.mainloop = mainloop,
};