bounce_template.c

[詳解]

/*++
/* 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)
/*  int IS_VERIFY_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
/*--*/

/* 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>

/* Application-specific. */

#include <bounce_template.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->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", tp->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", tp->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);
}