File: smtp-refuser.c

package info (click to toggle)
smtp-refuser 1.0.5.0.1
  • links: PTS
  • area: main
  • in suites: etch, etch-m68k
  • size: 84 kB
  • ctags: 18
  • sloc: ansic: 209; sh: 70; makefile: 43
file content (243 lines) | stat: -rw-r--r-- 5,009 bytes parent folder | download | duplicates (5)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <time.h>

static void	data(int argc, char * * argv);
static void	error(int argc, char * * argv);
static void	helo(int argc, char * * argv);
static void	help(int argc, char * * argv);
static void	ok(int argc, char * * argv);
static void	quit(int argc, char * * argv);
static void	refuse(int argc, char * * argv);
static void	send_file(int error_number, FILE * file, int argc, char * * argv);

struct command {
    const char	name[4];
    void	(*function)(int argc, char * * argv);
};

static const struct command	commands[] = {
    {	"data",	data	},
    {	"debu",	refuse	},
    {	"expn",	refuse	},
    {	"helo",	helo	},
    {	"help",	help	},
    {	"mail",	ok	},
    {	"noop",	ok	},
    {	"rcpt",	refuse	},
    {	"rset",	ok	},
    {	"quit",	quit	},
    {	"vrfy",	refuse	},
    {	"",		error	}
};

static char	hostname[100];
static char	bouncerName[100], bouncerPhone[100];

static const char *
get_line(char * buffer, int length, FILE * stream)
{
    int	c;
    int	got_one = 0;

    length--;

    while ( length > 0 && (c = fgetc(stream)) != EOF ) {
	if ( c == '\r' || c == '\n' ) {
	    if ( got_one )
		break;
	    else
		continue;
	}
	*buffer++ = c;
	got_one = 1;
    }
    *buffer = '\0';
    if ( got_one )
	return buffer;
    else
	return 0;
}

static void
timeout(int signal_number)
{
    /* Don't hold resources for over a minute just to bounce a message */
    shutdown(0, 2);
    shutdown(1, 2);
    shutdown(2, 2);
    _exit(0);
}

int
main(int argc, char * * argv)
{
    char		buffer[1024];
    time_t		t = time(0);
    char *		date = ctime(&t);
#ifdef LOGFILE
    FILE *		log;
#endif
    FILE *		bouncer;

    signal(SIGALRM, timeout);
    alarm(60);

#ifdef LOGFILE
    log = fopen(LOGFILE, "w");
#endif

    bouncer = fopen("/etc/smtp-refuser.conf", "r");
    get_line(bouncerName, sizeof(bouncerName), bouncer);
    get_line(bouncerPhone, sizeof(bouncerPhone), bouncer);
    fclose(bouncer);

    if ( gethostname(hostname, sizeof(hostname)) != 0 )
	hostname[0] = '\0';

    date[strlen(date) - 1] = '\0';
    setlinebuf(stdout);

    printf("220 %s smtp-refuser ready at %s.\r\n", hostname, date);
    while ( get_line(buffer, sizeof(buffer), stdin) != NULL ) {
	const struct command *	c = commands;

#ifdef LOGFILE
	if ( log )
	    fprintf(log, "%s\n", buffer);
#endif

	while ( *(c->name) && strncasecmp(buffer, c->name, 4) != 0 )
	    c++;

	(c->function)(argc, argv);
    } 
    return 0;
}

static void
data(int argc, char * * argv)
{
    fputs("503 No recepients are valid.\r\n", stdout);
}

static void
error(int argc, char * * argv)
{
    fputs("500 Command unrecognized.\r\n", stdout);
}

static void
helo(int argc, char * * argv)
{
    printf(
     "250 %s ready. You are not welcome here.\r\n"
    ,hostname);
}

static void
help(int argc, char * * argv)
{
    static const char	help_text[] =
     "250-This server exists only to refuse mail.\r\n"
     "250-Your system has been directed to it instead of the normal mail\r\n"
     "250-server because the system administrator has some reason to\r\n"
     "250-refuse your messages. If you feel this is an error, please\r\n"
     "250 contact the system administrator using other means than e-mail.\r\n";

    fputs(help_text, stdout);
}

static void
ok(int argc, char * * argv)
{
    fputs("250 ok. Any mail you send will be rejected.\r\n", stdout);
}

static void
quit(int argc, char * * argv)
{
    printf(
     "221 %s closing connection. Please don't bother us again.\r\n"
    ,hostname);
    exit(0);
}

static void
send_file(int error_number, FILE * file, int argc, char * * argv)
{
    int	c;
    int escape = 0;
    int dollar = 0;
    int new_line = 1;

    while ( (c = getc(file)) != EOF ) {
	if ( new_line ) {
	    printf("%d- ", error_number);
	    new_line = 0;
	}

	if ( !escape ) {
	    switch ( c ) {
	    case '\\':
		escape = 1;
		continue;
	    case '$':
		dollar = 1;
		continue;
	    case '\n':
		printf("\r\n", error_number);
		new_line = 1;
		continue;
	    }
	    if ( dollar ) {
		if ( c >= '1' && c <= '9' && argc > (c - '0') ) {
		    fputs(argv[c - '0'], stdout);
		    dollar = 0;
		    continue;
		}
		if ( c == 'c' || c == 'C' ) {
		    fputs(bouncerName, stdout);
		    dollar = 0;
		    continue;
		}
		if ( c == 'p' || c == 'P' ) {
		    fputs(bouncerPhone, stdout);
		    dollar = 0;
		    continue;
		}
	    }
	}
	escape = 0;
	dollar = 0;
	putchar(c);
    }
    printf("%d \r\n", error_number);
}

static void
refuse(int argc, char * * argv)
{
    FILE *		file = NULL;
    static const char	text[] = 
     "550- All mail from your site is refused. If you feel this is an\r\n"
     "550- error, please contact the system administrator using other\r\n"
     "550 means than e-mail.\r\n";

    if ( argc > 1 )
	file = fopen(argv[1], "r");

    if ( file == NULL ) {
	fputs(text, stdout);
	return;
    }

    argc--;
    argv++;
    send_file(550, file, argc, argv);

    fclose(file);
}