resolve_clnt.c

[詳解]

/*++
/* NAME
/*  resolve_clnt 3
/* SUMMARY
/*  address resolve service client (internal forms)
/* SYNOPSIS
/*  #include <resolve_clnt.h>
/*
/*  typedef struct {
/* .in +4
/*      VSTRING *transport;
/*      VSTRING *nexthop
/*      VSTRING *recipient;
/*      int flags;
/* .in -4
/*  } RESOLVE_REPLY;
/*
/*  void    resolve_clnt_init(reply)
/*  RESOLVE_REPLY *reply;
/*
/*  void    resolve_clnt_query_from(sender, address, reply)
/*  const char *sender;
/*  const char *address;
/*  RESOLVE_REPLY *reply;
/*
/*  void    resolve_clnt_verify_from(sender, address, reply)
/*  const char *sender;
/*  const char *address;
/*  RESOLVE_REPLY *reply;
/*
/*  void    resolve_clnt_free(reply)
/*  RESOLVE_REPLY *reply;
/* DESCRIPTION
/*  This module implements a mail address resolver client.
/*
/*  resolve_clnt_init() initializes a reply data structure for use
/*  by resolve_clnt_query(). The structure is destroyed by passing
/*  it to resolve_clnt_free().
/*
/*  resolve_clnt_query_from() sends an internal-form recipient address
/*  (user@domain) to the resolver daemon and returns the resulting
/*  transport name, next_hop host name, and internal-form recipient
/*  address. In case of communication failure the program keeps trying
/*  until the mail system goes down. The internal-form sender
/*  information is used for sender-dependent relayhost lookup.
/*  Specify RESOLVE_NULL_FROM when the sender is unavailable.
/*
/*  resolve_clnt_verify_from() implements an alternative version that can
/*  be used for address verification.
/*
/*  In the resolver reply, the flags member is the bit-wise OR of
/*  zero or more of the following:
/* .IP RESOLVE_FLAG_FINAL
/*  The recipient address resolves to a mail transport that performs
/*  final delivery. The destination is local or corresponds to a hosted
/*  domain that is handled by the local machine. This flag is currently
/*  not used.
/* .IP RESOLVE_FLAG_ROUTED
/*  After address resolution the recipient localpart contains further
/*  routing information, so the resolved next-hop destination is not
/*  the final destination.
/* .IP RESOLVE_FLAG_ERROR
/*  The address resolved to something that has invalid syntax.
/* .IP RESOLVE_FLAG_FAIL
/*  The request could not be completed.
/* .PP
/*  In addition, the address domain class is returned by setting
/*  one of the following flags (this is preliminary code awaiting
/*  more permanent implementation of address domain class handling):
/* .IP RESOLVE_CLASS_LOCAL
/*  The address domain matches $mydestination, $inet_interfaces
/*  or $proxy_interfaces.
/* .IP RESOLVE_CLASS_ALIAS
/*  The address domain matches $virtual_alias_domains (virtual
/*  alias domains, where each address is redirected to a real
/*  local or remote address).
/* .IP RESOLVE_CLASS_VIRTUAL
/*  The address domain matches $virtual_mailbox_domains (true
/*  virtual domains where each address can have its own mailbox).
/* .IP RESOLVE_CLASS_RELAY
/*  The address domain matches $relay_domains, i.e. this is an
/*  authorized mail relay destination.
/* .IP RESOLVE_CLASS_DEFAULT
/*  The address matches none of the above. Access to this domain
/*  should be limited to authorized senders only.
/* .PP
/*  For convenience, the constant RESOLVE_CLASS_FINAL includes all
/*  cases where the local machine is the final destination.
/* DIAGNOSTICS
/*  Warnings: communication failure. Fatal error: mail system is down.
/* SEE ALSO
/*  mail_proto(3h) low-level mail component glue.
/* 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 <unistd.h>
#include <string.h>
#include <errno.h>

/* Utility library. */

#include <msg.h>
#include <vstream.h>
#include <vstring.h>
#include <vstring_vstream.h>
#include <events.h>
#include <iostuff.h>

/* Global library. */

#include "mail_proto.h"
#include "mail_params.h"
#include "clnt_stream.h"
#include "resolve_clnt.h"

/* Application-specific. */

 /*
  * XXX this is shared with the rewrite client to save a file descriptor.
  */
extern CLNT_STREAM *rewrite_clnt_stream;

static time_t last_expire;
static VSTRING *last_class;
static VSTRING *last_sender;
static VSTRING *last_addr;
static RESOLVE_REPLY last_reply;

/* resolve_clnt_init - initialize reply */

void    resolve_clnt_init(RESOLVE_REPLY *reply)
{
    reply->transport = vstring_alloc(100);
    reply->nexthop = vstring_alloc(100);
    reply->recipient = vstring_alloc(100);
    reply->flags = 0;
}

/* resolve_clnt - resolve address to (transport, next hop, recipient) */

void    resolve_clnt(const char *class, const char *sender,
                     const char *addr, RESOLVE_REPLY *reply)
{
    const char *myname = "resolve_clnt";
    VSTREAM *stream;
    int     server_flags;
    int     count = 0;

    /*
     * One-entry cache.
     */
    if (last_addr == 0) {
    last_class = vstring_alloc(10);
    last_sender = vstring_alloc(10);
    last_addr = vstring_alloc(100);
    resolve_clnt_init(&last_reply);
    }

    /*
     * Sanity check. The result must not clobber the input because we may
     * have to retransmit the request.
     */
#define STR vstring_str

    if (addr == STR(reply->recipient))
    msg_panic("%s: result clobbers input", myname);

    /*
     * Peek at the cache.
     */
#define IFSET(flag, text) ((reply->flags & (flag)) ? (text) : "")

    if (time((time_t *) 0) < last_expire
    && *addr && strcmp(addr, STR(last_addr)) == 0
    && strcmp(class, STR(last_class)) == 0
    && strcmp(sender, STR(last_sender)) == 0) {
    vstring_strcpy(reply->transport, STR(last_reply.transport));
    vstring_strcpy(reply->nexthop, STR(last_reply.nexthop));
    vstring_strcpy(reply->recipient, STR(last_reply.recipient));
    reply->flags = last_reply.flags;
    if (msg_verbose)
        msg_info("%s: cached: `%s' -> `%s' -> transp=`%s' host=`%s' rcpt=`%s' flags=%s%s%s%s class=%s%s%s%s%s",
             myname, sender, addr, STR(reply->transport),
             STR(reply->nexthop), STR(reply->recipient),
             IFSET(RESOLVE_FLAG_FINAL, "final"),
             IFSET(RESOLVE_FLAG_ROUTED, "routed"),
             IFSET(RESOLVE_FLAG_ERROR, "error"),
             IFSET(RESOLVE_FLAG_FAIL, "fail"),
             IFSET(RESOLVE_CLASS_LOCAL, "local"),
             IFSET(RESOLVE_CLASS_ALIAS, "alias"),
             IFSET(RESOLVE_CLASS_VIRTUAL, "virtual"),
             IFSET(RESOLVE_CLASS_RELAY, "relay"),
             IFSET(RESOLVE_CLASS_DEFAULT, "default"));
    return;
    }

    /*
     * Keep trying until we get a complete response. The resolve service is
     * CPU bound; making the client asynchronous would just complicate the
     * code.
     */
    if (rewrite_clnt_stream == 0)
    rewrite_clnt_stream = clnt_stream_create(MAIL_CLASS_PRIVATE,
                         var_rewrite_service,
                         var_ipc_idle_limit,
                         var_ipc_ttl_limit);

    for (;;) {
    stream = clnt_stream_access(rewrite_clnt_stream);
    errno = 0;
    count += 1;
    if (attr_print(stream, ATTR_FLAG_NONE,
               SEND_ATTR_STR(MAIL_ATTR_REQ, class),
               SEND_ATTR_STR(MAIL_ATTR_SENDER, sender),
               SEND_ATTR_STR(MAIL_ATTR_ADDR, addr),
               ATTR_TYPE_END) != 0
        || vstream_fflush(stream)
        || attr_scan(stream, ATTR_FLAG_STRICT,
             RECV_ATTR_INT(MAIL_ATTR_FLAGS, &server_flags),
               RECV_ATTR_STR(MAIL_ATTR_TRANSPORT, reply->transport),
             RECV_ATTR_STR(MAIL_ATTR_NEXTHOP, reply->nexthop),
             RECV_ATTR_STR(MAIL_ATTR_RECIP, reply->recipient),
             RECV_ATTR_INT(MAIL_ATTR_FLAGS, &reply->flags),
             ATTR_TYPE_END) != 5) {
        if (msg_verbose || count > 1 || (errno && errno != EPIPE && errno != ENOENT))
        msg_warn("problem talking to service %s: %m",
             var_rewrite_service);
    } else {
        if (msg_verbose)
        msg_info("%s: `%s' -> `%s' -> transp=`%s' host=`%s' rcpt=`%s' flags=%s%s%s%s class=%s%s%s%s%s",
             myname, sender, addr, STR(reply->transport),
             STR(reply->nexthop), STR(reply->recipient),
             IFSET(RESOLVE_FLAG_FINAL, "final"),
             IFSET(RESOLVE_FLAG_ROUTED, "routed"),
             IFSET(RESOLVE_FLAG_ERROR, "error"),
             IFSET(RESOLVE_FLAG_FAIL, "fail"),
             IFSET(RESOLVE_CLASS_LOCAL, "local"),
             IFSET(RESOLVE_CLASS_ALIAS, "alias"),
             IFSET(RESOLVE_CLASS_VIRTUAL, "virtual"),
             IFSET(RESOLVE_CLASS_RELAY, "relay"),
             IFSET(RESOLVE_CLASS_DEFAULT, "default"));
        /* Server-requested disconnect. */
        if (server_flags != 0)
        clnt_stream_recover(rewrite_clnt_stream);
        if (STR(reply->transport)[0] == 0)
        msg_warn("%s: null transport result for: <%s>", myname, addr);
        else if (STR(reply->recipient)[0] == 0 && *addr != 0)
        msg_warn("%s: null recipient result for: <%s>", myname, addr);
        else
        break;
    }
    sleep(1);               /* XXX make configurable */
    clnt_stream_recover(rewrite_clnt_stream);
    }

    /*
     * Update the cache.
     */
    vstring_strcpy(last_class, class);
    vstring_strcpy(last_sender, sender);
    vstring_strcpy(last_addr, addr);
    vstring_strcpy(last_reply.transport, STR(reply->transport));
    vstring_strcpy(last_reply.nexthop, STR(reply->nexthop));
    vstring_strcpy(last_reply.recipient, STR(reply->recipient));
    last_reply.flags = reply->flags;
    last_expire = time((time_t *) 0) + 30;  /* XXX make configurable */
}

/* resolve_clnt_free - destroy reply */

void    resolve_clnt_free(RESOLVE_REPLY *reply)
{
    reply->transport = vstring_free(reply->transport);
    reply->nexthop = vstring_free(reply->nexthop);
    reply->recipient = vstring_free(reply->recipient);
}

#ifdef TEST

#include <stdlib.h>
#include <msg_vstream.h>
#include <vstring_vstream.h>
#include <split_at.h>
#include <mail_conf.h>

static NORETURN usage(char *myname)
{
    msg_fatal("usage: %s [-v] [address...]", myname);
}

static void resolve(char *class, char *addr, RESOLVE_REPLY *reply)
{
    struct RESOLVE_FLAG_TABLE {
    int     flag;
    const char *name;
    };
    struct RESOLVE_FLAG_TABLE resolve_flag_table[] = {
    RESOLVE_FLAG_FINAL, "FLAG_FINAL",
    RESOLVE_FLAG_ROUTED, "FLAG_ROUTED",
    RESOLVE_FLAG_ERROR, "FLAG_ERROR",
    RESOLVE_FLAG_FAIL, "FLAG_FAIL",
    RESOLVE_CLASS_LOCAL, "CLASS_LOCAL",
    RESOLVE_CLASS_ALIAS, "CLASS_ALIAS",
    RESOLVE_CLASS_VIRTUAL, "CLASS_VIRTUAL",
    RESOLVE_CLASS_RELAY, "CLASS_RELAY",
    RESOLVE_CLASS_DEFAULT, "CLASS_DEFAULT",
    0,
    };
    struct RESOLVE_FLAG_TABLE *fp;

    resolve_clnt(class, RESOLVE_NULL_FROM, addr, reply);
    if (reply->flags & RESOLVE_FLAG_FAIL) {
    vstream_printf("request failed\n");
    } else {
    vstream_printf("%-10s %s\n", "class", class);
    vstream_printf("%-10s %s\n", "address", addr);
    vstream_printf("%-10s %s\n", "transport", STR(reply->transport));
    vstream_printf("%-10s %s\n", "nexthop", *STR(reply->nexthop) ?
               STR(reply->nexthop) : "[none]");
    vstream_printf("%-10s %s\n", "recipient", STR(reply->recipient));
    vstream_printf("%-10s ", "flags");
    for (fp = resolve_flag_table; fp->name; fp++) {
        if (reply->flags & fp->flag) {
        vstream_printf("%s ", fp->name);
        reply->flags &= ~fp->flag;
        }
    }
    if (reply->flags != 0)
        vstream_printf("Unknown flag 0x%x", reply->flags);
    vstream_printf("\n\n");
    vstream_fflush(VSTREAM_OUT);
    }
}

int     main(int argc, char **argv)
{
    RESOLVE_REPLY reply;
    char   *addr;
    int     ch;

    msg_vstream_init(argv[0], VSTREAM_ERR);

    mail_conf_read();
    msg_info("using config files in %s", var_config_dir);
    if (chdir(var_queue_dir) < 0)
    msg_fatal("chdir %s: %m", var_queue_dir);

    while ((ch = GETOPT(argc, argv, "v")) > 0) {
    switch (ch) {
    case 'v':
        msg_verbose++;
        break;
    default:
        usage(argv[0]);
    }
    }
    resolve_clnt_init(&reply);

    if (argc > optind) {
    while (argv[optind] && argv[optind + 1]) {
        resolve(argv[optind], argv[optind + 1], &reply);
        optind += 2;
    }
    } else {
    VSTRING *buffer = vstring_alloc(1);

    while (vstring_fgets_nonl(buffer, VSTREAM_IN)) {
        addr = split_at(STR(buffer), ' ');
        if (*STR(buffer) == 0)
        msg_fatal("need as input: class [address]");
        if (addr == 0)
        addr = "";
        resolve(STR(buffer), addr, &reply);
    }
    vstring_free(buffer);
    }
    resolve_clnt_free(&reply);
    exit(0);
}

#endif