/* $NetBSD: bounce_template.c,v 1.4 2022/10/08 16:12:45 christos Exp $ */
/*++
/* NAME
/* bounce_template 3
/* SUMMARY
/* bounce template support
/* SYNOPSIS
/* #include <bounce_template.h>
/*
/* BOUNCE_TEMPLATE *bounce_template_create(def_template)
/* const BOUNCE_TEMPLATE *def_template;
/*
/* void bounce_template_free(template)
/* BOUNCE_TEMPLATE *template;
/*
/* void bounce_template_load(template, stream, buffer, origin)
/* BOUNCE_TEMPLATE *template;
/* VSTREAM *stream;
/* const char *buffer;
/* const char *origin;
/*
/* void bounce_template_headers(out_fn, stream, template,
/* rcpt, postmaster_copy)
/* int (*out_fn)(VSTREAM *, const char *, ...);
/* VSTREAM *stream;
/* BOUNCE_TEMPLATE *template;
/* const char *rcpt;
/* int postmaster_copy;
/*
/* const char *bounce_template_encoding(template)
/* BOUNCE_TEMPLATE *template;
/*
/* const char *bounce_template_charset(template)
/* BOUNCE_TEMPLATE *template;
/*
/* void bounce_template_expand(out_fn, stream, template)
/* int (*out_fn)(VSTREAM *, const char *);
/* VSTREAM *stream;
/* BOUNCE_TEMPLATE *template;
/*
/* void bounce_template_dump(stream, template)
/* VSTREAM *stream;
/* BOUNCE_TEMPLATE *template;
/*
/* int IS_FAILURE_TEMPLATE(template)
/* int IS_DELAY_TEMPLATE(template)
/* int IS_SUCCESS_TEMPLATE(template)
/* BOUNCE_TEMPLATE *template;
/* DESCRIPTION
/* This module implements the built-in and external bounce
/* message template support. The content of a template are
/* private. To access information within a template, use
/* the API described in this document.
/*
/* bounce_template_create() creates a template, with the
/* specified default settings. The template defaults are not
/* copied.
/*
/* bounce_template_free() destroys a bounce message template.
/*
/* bounce_template_load() overrides a bounce template with the
/* specified buffer from the specified origin. The buffer and
/* origin are copied. Specify a null buffer and origin pointer
/* to reset the template to the defaults specified with
/* bounce_template_create().
/*
/* bounce_template_headers() sends the postmaster or non-postmaster
/* From/Subject/To message headers to the specified stream.
/* The recipient address is expected to be in RFC822 external
/* form. The postmaster_copy argument is one of POSTMASTER_COPY
/* or NO_POSTMASTER_COPY.
/*
/* bounce_template_encoding() returns the encoding (MAIL_ATTR_ENC_7BIT
/* or MAIL_ATTR_ENC_8BIT) for the bounce template message text.
/*
/* bounce_template_charset() returns the character set for the
/* bounce template message text.
/*
/* bounce_template_expand() expands the body text of the
/* specified template and writes the result to the specified
/* stream.
/*
/* bounce_template_dump() dumps the specified template to the
/* specified stream.
/*
/* The IS_MUMBLE_TEMPLATE() macros are predicates that
/* determine whether the template is of the specified type.
/* DIAGNOSTICS
/* Fatal error: out of memory, undefined macro name in template.
/* SEE ALSO
/* bounce_templates(3) bounce template group support
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*
/* Wietse Venema
/* Google, Inc.
/* 111 8th Avenue
/* New York, NY 10011, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <string.h>
#include <ctype.h>
#ifdef STRCASECMP_IN_STRINGS_H
#include <strings.h>
#endif
/* Utility library. */
#include <msg.h>
#include <mac_expand.h>
#include <split_at.h>
#include <stringops.h>
#include <mymalloc.h>
#ifndef NO_EAI
#include <midna_domain.h>
#endif
/* Global library. */
#include <mail_params.h>
#include <mail_proto.h>
#include <mail_conf.h>
#include <is_header.h>
#include <hfrom_format.h>
/* Application-specific. */
#include <bounce_template.h>
#include <bounce_service.h>
/*
* The following tables implement support for bounce template expansions of
* $<parameter_name>_days ($<parameter_name>_hours, etc.). The expansion of
* these is the actual parameter value divided by the number of seconds in a
* day (hour, etc.), so that we can produce nicely formatted bounce messages
* with time values converted into the appropriate units.
*
* Ideally, the bounce template processor would strip the _days etc. suffix
* from the parameter name, and use the parameter name to look up the actual
* parameter value and its default value (the default value specifies the
* default time unit of that parameter (seconds, minutes, etc.)), and use
* this to convert the parameter string value into the corresponding number
* of seconds. The bounce template processor would then use the _hours etc.
* suffix from the bounce template to divide this number by the number of
* seconds in an hour, etc. and produce the number that is needed for the
* template.
*
* Unfortunately, there exists no code to look up default values by parameter
* name. If such code existed, then we could do the _days, _hours, etc.
* conversion with every main.cf time parameter without having to know in
* advance what time parameter names exist.
*
* So we have to either maintain our own table of all time related main.cf
* parameter names and defaults (like the postconf command does) or we make
* a special case for a few parameters of special interest.
*
* We go for the second solution. There are only a few parameters that need
* this treatment, and there will be more special cases when individual
* queue files get support for individual expiration times, and when other
* queue file information needs to be reported in bounce template messages.
*
* A really lame implementation would simply strip the optional s, h, d, etc.
* suffix from the actual (string) parameter value and not do any conversion
* at all to hours, days or weeks. But then the information in delay warning
* notices could be seriously incorrect.
*/
typedef struct {
const char *suffix; /* days, hours, etc. */
int suffix_len; /* byte count */
int divisor; /* divisor */
} BOUNCE_TIME_DIVISOR;
#define STRING_AND_LEN(x) (x), (sizeof(x) - 1)
static const BOUNCE_TIME_DIVISOR time_divisors[] = {
STRING_AND_LEN("seconds"), 1,
STRING_AND_LEN("minutes"), 60,
STRING_AND_LEN("hours"), 60 * 60,
STRING_AND_LEN("days"), 24 * 60 * 60,
STRING_AND_LEN("weeks"), 7 * 24 * 60 * 60,
0, 0,
};
/*
* The few special-case main.cf parameters that have support for _days, etc.
* suffixes for automatic conversion when expanded into a bounce template.
*/
typedef struct {
const char *param_name; /* parameter name */
int param_name_len; /* name length */
int *value; /* parameter value */
} BOUNCE_TIME_PARAMETER;
static const BOUNCE_TIME_PARAMETER time_parameter[] = {
STRING_AND_LEN(VAR_DELAY_WARN_TIME), &var_delay_warn_time,
STRING_AND_LEN(VAR_MAX_QUEUE_TIME), &var_max_queue_time,
0, 0,
};
/*
* Parameters whose value may have to be converted to UTF-8 for presentation
* purposes.
*/
typedef struct {
const char *param_name; /* parameter name */
char **value; /* parameter value */
} BOUNCE_STR_PARAMETER;
static const BOUNCE_STR_PARAMETER str_parameter[] = {
VAR_MYHOSTNAME, &var_myhostname,
VAR_MYDOMAIN, &var_mydomain,
0, 0,
};
/*
* SLMs.
*/
#define STR(x) vstring_str(x)
/* bounce_template_create - create one template */
BOUNCE_TEMPLATE *bounce_template_create(const BOUNCE_TEMPLATE *prototype)
{
BOUNCE_TEMPLATE *tp;
tp = (BOUNCE_TEMPLATE *) mymalloc(sizeof(*tp));
*tp = *prototype;
return (tp);
}
/* bounce_template_free - destroy one template */
void bounce_template_free(BOUNCE_TEMPLATE *tp)
{
if (tp->buffer) {
myfree(tp->buffer);
myfree((void *) tp->origin);
}
myfree((void *) tp);
}
/* bounce_template_reset - reset template to default */
static void bounce_template_reset(BOUNCE_TEMPLATE *tp)
{
myfree(tp->buffer);
myfree((void *) tp->origin);
*tp = *(tp->prototype);
}
/* bounce_template_load - override one template */
void bounce_template_load(BOUNCE_TEMPLATE *tp, const char *origin,
const char *buffer)
{
/*
* Clean up after a previous call.
*/
if (tp->buffer)
bounce_template_reset(tp);
/*
* Postpone the work of template parsing until it is really needed. Most
* bounce service calls never need a template.
*/
if (buffer && origin) {
tp->flags |= BOUNCE_TMPL_FLAG_NEW_BUFFER;
tp->buffer = mystrdup(buffer);
tp->origin = mystrdup(origin);
}
}
/* bounce_template_parse_buffer - initialize template */
static void bounce_template_parse_buffer(BOUNCE_TEMPLATE *tp)
{
char *tval = tp->buffer;
char *cp;
char **cpp;
int cpp_len;
int cpp_used;
int hlen;
char *hval;
/*
* Sanity check.
*/
if ((tp->flags & BOUNCE_TMPL_FLAG_NEW_BUFFER) == 0)
msg_panic("bounce_template_parse_buffer: nothing to do here");
tp->flags &= ~BOUNCE_TMPL_FLAG_NEW_BUFFER;
/*
* Discard the unusable template and use the default one instead.
*/
#define CLEANUP_AND_RETURN() do { \
bounce_template_reset(tp); \
return; \
} while (0)
/*
* Parse pseudo-header labels and values.
*
* XXX EAI: allow UTF8 in template headers when responding to SMTPUTF8
* message. Sending SMTPUTF8 in response to non-SMTPUTF8 mail would make
* no sense.
*/
#define GETLINE(line, buf) \
(((line) = (buf)) != 0 ? ((buf) = split_at((buf), '\n'), (line)) : 0)
while ((GETLINE(cp, tval)) != 0 && (hlen = is_header(cp)) > 0) {
for (hval = cp + hlen; *hval && (*hval == ':' || ISSPACE(*hval)); hval++)
*hval = 0;
if (*hval == 0) {
msg_warn("%s: empty \"%s\" header value in %s template "
"-- ignoring this template",
tp->origin, cp, tp->class);
CLEANUP_AND_RETURN();
}
if (!allascii(hval)) {
msg_warn("%s: non-ASCII \"%s\" header value in %s template "
"-- ignoring this template",
tp->origin, cp, tp->class);
CLEANUP_AND_RETURN();
}
if (strcasecmp("charset", cp) == 0) {
tp->mime_charset = hval;
} else if (strcasecmp("from", cp) == 0) {
tp->std_from = tp->obs_from = hval;
} else if (strcasecmp("subject", cp) == 0) {
tp->subject = hval;
} else if (strcasecmp("postmaster-subject", cp) == 0) {
if (tp->postmaster_subject == 0) {
msg_warn("%s: inapplicable \"%s\" header label in %s template "
"-- ignoring this template",
tp->origin, cp, tp->class);
CLEANUP_AND_RETURN();
}
tp->postmaster_subject = hval;
} else {
msg_warn("%s: unknown \"%s\" header label in %s template "
"-- ignoring this template",
tp->origin, cp, tp->class);
CLEANUP_AND_RETURN();
}
}
/*
* Skip blank lines between header and message text.
*/
while (cp && (*cp == 0 || allspace(cp)))
(void) GETLINE(cp, tval);
if (cp == 0) {
msg_warn("%s: missing message text in %s template "
"-- ignoring this template",
tp->origin, tp->class);
CLEANUP_AND_RETURN();
}
/*
* Is this 7bit or 8bit text? If the character set is US-ASCII, then
* don't allow 8bit text. Don't assume 8bit when charset was changed.
*/
#define NON_ASCII(p) ((p) && *(p) && !allascii((p)))
if (NON_ASCII(cp) || NON_ASCII(tval)) {
if (strcasecmp(tp->mime_charset, "us-ascii") == 0) {
msg_warn("%s: 8-bit message text in %s template",
tp->origin, tp->class);
msg_warn("please specify a charset value other than us-ascii");
msg_warn("-- ignoring this template for now");
CLEANUP_AND_RETURN();
}
tp->mime_encoding = MAIL_ATTR_ENC_8BIT;
}
/*
* Collect the message text and null-terminate the result.
*/
cpp_len = 10;
cpp_used = 0;
cpp = (char **) mymalloc(sizeof(*cpp) * cpp_len);
while (cp) {
cpp[cpp_used++] = cp;
if (cpp_used >= cpp_len) {
cpp = (char **) myrealloc((void *) cpp,
sizeof(*cpp) * 2 * cpp_len);
cpp_len *= 2;
}
(void) GETLINE(cp, tval);
}
cpp[cpp_used] = 0;
tp->message_text = (const char **) cpp;
}
/* bounce_template_lookup - lookup $name value */
static const char *bounce_template_lookup(const char *key, int unused_mode,
void *context)
{
BOUNCE_TEMPLATE *tp = (BOUNCE_TEMPLATE *) context;
const BOUNCE_TIME_PARAMETER *bp;
const BOUNCE_TIME_DIVISOR *bd;
const BOUNCE_STR_PARAMETER *sp;
static VSTRING *buf;
int result;
const char *asc_val;
const char *utf8_val;
/*
* Look for parameter names that can have a time unit suffix, and scale
* the time value according to the suffix.
*/
for (bp = time_parameter; bp->param_name; bp++) {
if (strncmp(key, bp->param_name, bp->param_name_len) == 0
&& key[bp->param_name_len] == '_') {
for (bd = time_divisors; bd->suffix; bd++) {
if (strcmp(key + bp->param_name_len + 1, bd->suffix) == 0) {
result = bp->value[0] / bd->divisor;
if (result > 999 && bd->divisor < 86400) {
msg_warn("%s: excessive result \"%d\" in %s "
"template conversion of parameter \"%s\"",
tp->origin, result, tp->class, key);
msg_warn("please increase time unit \"%s\" of \"%s\" "
"in %s template", bd->suffix, key, tp->class);
msg_warn("for instructions see the bounce(5) manual");
} else if (result == 0 && bp->value[0] && bd->divisor > 1) {
msg_warn("%s: zero result in %s template "
"conversion of parameter \"%s\"",
tp->origin, tp->class, key);
msg_warn("please reduce time unit \"%s\" of \"%s\" "
"in %s template", bd->suffix, key, tp->class);
msg_warn("for instructions see the bounce(5) manual");
}
if (buf == 0)
buf = vstring_alloc(10);
vstring_sprintf(buf, "%d", result);
return (STR(buf));
}
}
msg_fatal("%s: unrecognized suffix \"%s\" in parameter \"%s\"",
tp->origin,
key + bp->param_name_len + 1, key);
}
}
/*
* Look for parameter names that may have to be up-converted for
* presentation purposes.
*/
#ifndef NO_EAI
if (var_smtputf8_enable) {
for (sp = str_parameter; sp->param_name; sp++) {
if (strcmp(key, sp->param_name) == 0) {
asc_val = sp->value[0];
if (!allascii(asc_val)) {
msg_warn("%s: conversion \"%s\" failed: "
"non-ASCII input value: \"%s\"",
tp->origin, key, asc_val);
return (asc_val);
} else if ((utf8_val = midna_domain_to_utf8(asc_val)) == 0) {
msg_warn("%s: conversion \"%s\" failed: "
"input value: \"%s\"",
tp->origin, key, asc_val);
return (asc_val);
} else {
return (utf8_val);
}
}
}
}
#endif
return (mail_conf_lookup_eval(key));
}
/* bounce_template_headers - send template headers */
void bounce_template_headers(BOUNCE_XP_PRN_FN out_fn, VSTREAM *fp,
BOUNCE_TEMPLATE *tp,
const char *rcpt,
int postmaster_copy)
{
if (tp->flags & BOUNCE_TMPL_FLAG_NEW_BUFFER)
bounce_template_parse_buffer(tp);
out_fn(fp, "From: %s", bounce_hfrom_format == HFROM_FORMAT_CODE_STD ?
tp->std_from : tp->obs_from);
out_fn(fp, "Subject: %s", tp->postmaster_subject && postmaster_copy ?
tp->postmaster_subject : tp->subject);
out_fn(fp, "To: %s", rcpt);
}
/* bounce_template_expand - expand template to stream */
void bounce_template_expand(BOUNCE_XP_PUT_FN out_fn, VSTREAM *fp,
BOUNCE_TEMPLATE *tp)
{
VSTRING *buf = vstring_alloc(100);
const char **cpp;
int stat;
if (tp->flags & BOUNCE_TMPL_FLAG_NEW_BUFFER)
bounce_template_parse_buffer(tp);
for (cpp = tp->message_text; *cpp; cpp++) {
stat = mac_expand(buf, *cpp, MAC_EXP_FLAG_PRINTABLE, (char *) 0,
bounce_template_lookup, (void *) tp);
if (stat & MAC_PARSE_ERROR)
msg_fatal("%s: bad $name syntax in %s template: %s",
tp->origin, tp->class, *cpp);
if (stat & MAC_PARSE_UNDEF)
msg_fatal("%s: undefined $name in %s template: %s",
tp->origin, tp->class, *cpp);
out_fn(fp, STR(buf));
}
vstring_free(buf);
}
/* bounce_template_dump - dump template to stream */
void bounce_template_dump(VSTREAM *fp, BOUNCE_TEMPLATE *tp)
{
const char **cpp;
if (tp->flags & BOUNCE_TMPL_FLAG_NEW_BUFFER)
bounce_template_parse_buffer(tp);
vstream_fprintf(fp, "Charset: %s\n", tp->mime_charset);
vstream_fprintf(fp, "From: %s\n", bounce_hfrom_format == HFROM_FORMAT_CODE_STD ?
tp->std_from : tp->obs_from);
vstream_fprintf(fp, "Subject: %s\n", tp->subject);
if (tp->postmaster_subject)
vstream_fprintf(fp, "Postmaster-Subject: %s\n",
tp->postmaster_subject);
vstream_fprintf(fp, "\n");
for (cpp = tp->message_text; *cpp; cpp++)
vstream_fprintf(fp, "%s\n", *cpp);
}