1 /* $NetBSD: postscreen_expand.c,v 1.2 2017/02/14 01:16:47 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* postscreen_expand 3
6 /* SUMMARY
7 /* SMTP server macro expansion
8 /* SYNOPSIS
9 /* #include <postscreen.h>
10 /*
11 /* void psc_expand_init()
12 /*
13 /* VSTRING *psc_expand_filter;
14 /*
15 /* const char *psc_expand_lookup(name, unused_mode, context)
16 /* const char *name;
17 /* int unused_mode;
18 /* char *context;
19 /* DESCRIPTION
20 /* This module expands session-related macros.
21 /*
22 /* psc_expand_init() performs one-time initialization
23 /* of the psc_expand_filter buffer.
24 /*
25 /* The psc_expand_filter buffer contains the characters
26 /* that are allowed in macro expansion, as specified with the
27 /* psc_expand_filter configuration parameter.
28 /*
29 /* psc_expand_lookup() returns the value of the named
30 /* macro or a null pointer.
31 /*
32 /* Arguments:
33 /* .IP name
34 /* Macro name.
35 /* .IP context
36 /* Call-back context (a PSC_STATE pointer).
37 /* DIAGNOSTICS
38 /* Panic: interface violations. Fatal errors: out of memory.
39 /* internal protocol errors. postscreen_expand() returns the
40 /* binary OR of MAC_PARSE_ERROR (syntax error) and MAC_PARSE_UNDEF
41 /* (undefined macro name).
42 /* LICENSE
43 /* .ad
44 /* .fi
45 /* The Secure Mailer license must be distributed with this software.
46 /* AUTHOR(S)
47 /* Wietse Venema
48 /* IBM T.J. Watson Research
49 /* P.O. Box 704
50 /* Yorktown Heights, NY 10598, USA
51 /*--*/
52
53 /* System library. */
54
55 #include <sys_defs.h>
56 #include <time.h>
57
58 /* Utility library. */
59
60 #include <msg.h>
61 #include <vstring.h>
62 #include <stringops.h>
63
64 /* Global library. */
65
66 #include <mail_params.h>
67 #include <mail_proto.h>
68
69 /* Application-specific. */
70
71 #include <postscreen.h>
72
73 /*
74 * Pre-parsed expansion filter.
75 */
76 VSTRING *psc_expand_filter;
77
78 /* psc_expand_init - initialize once during process lifetime */
79
psc_expand_init(void)80 void psc_expand_init(void)
81 {
82
83 /*
84 * Expand the expansion filter :-)
85 */
86 psc_expand_filter = vstring_alloc(10);
87 unescape(psc_expand_filter, var_psc_exp_filter);
88 }
89
90 /* psc_expand_lookup - generic SMTP attribute $name expansion */
91
psc_expand_lookup(const char * name,int unused_mode,void * context)92 const char *psc_expand_lookup(const char *name, int unused_mode,
93 void *context)
94 {
95 PSC_STATE *state = (PSC_STATE *) context;
96 time_t now;
97 struct tm *lt;
98
99 if (state->expand_buf == 0)
100 state->expand_buf = vstring_alloc(10);
101
102 if (msg_verbose > 1)
103 msg_info("psc_expand_lookup: ${%s}", name);
104
105 #define STREQ(x,y) (*(x) == *(y) && strcmp((x), (y)) == 0)
106 #define STREQN(x,y,n) (*(x) == *(y) && strncmp((x), (y), (n)) == 0)
107 #define CONST_LEN(x) (sizeof(x) - 1)
108
109 /*
110 * Don't query main.cf parameters, as the result of expansion could
111 * reveal system-internal information in server replies.
112 *
113 * XXX: This said, multiple servers may be behind a single client-visible
114 * name or IP address, and each may generate its own logs. Therefore, it
115 * may be useful to expose the replying MTA id (myhostname) in the
116 * contact footer, to identify the right logs. So while we don't expose
117 * the raw configuration dictionary, we do expose "$myhostname" as
118 * expanded in var_myhostname.
119 *
120 * Return NULL only for non-existent names.
121 */
122 if (STREQ(name, MAIL_ATTR_SERVER_NAME)) {
123 return (var_myhostname);
124 } else if (STREQ(name, MAIL_ATTR_ACT_CLIENT_ADDR)) {
125 return (state->smtp_client_addr);
126 } else if (STREQ(name, MAIL_ATTR_ACT_CLIENT_PORT)) {
127 return (state->smtp_client_port);
128 } if (STREQ(name, MAIL_ATTR_LOCALTIME)) {
129 if (time(&now) == (time_t) -1)
130 msg_fatal("time lookup failed: %m");
131 lt = localtime(&now);
132 VSTRING_RESET(state->expand_buf);
133 do {
134 VSTRING_SPACE(state->expand_buf, 100);
135 } while (strftime(STR(state->expand_buf),
136 vstring_avail(state->expand_buf),
137 "%b %d %H:%M:%S", lt) == 0);
138 return (STR(state->expand_buf));
139 } else {
140 msg_warn("unknown macro name \"%s\" in expansion request", name);
141 return (0);
142 }
143 }
144