sendmail/libmilter/comm.c

/*
 *  Copyright (c) 1999-2004, 2009 Proofpoint, Inc. and its suppliers.
 *  All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: comm.c,v 8.71 2013-11-22 20:51:36 ca Exp $")

#include "libmilter.h"
#include <sm/errstring.h>
#include <sys/uio.h>

static ssize_t  retry_writev __P((socket_t, struct iovec *, int, struct timeval *));
static size_t Maxdatasize = MILTER_MAX_DATA_SIZE;

/*
**  SMFI_SETMAXDATASIZE -- set limit for milter data read/write.
**
**  Parameters:
**      sz -- new limit.
**
**  Returns:
**      old limit
*/

size_t
smfi_setmaxdatasize(sz)
    size_t sz;
{
    size_t old;

    old = Maxdatasize;
    Maxdatasize = sz;
    return old;
}

/*
**  MI_RD_CMD -- read a command
**
**  Parameters:
**      sd -- socket descriptor
**      timeout -- maximum time to wait
**      cmd -- single character command read from sd
**      rlen -- pointer to length of result
**      name -- name of milter
**
**  Returns:
**      buffer with rest of command
**      (malloc()ed here, should be free()d)
**      hack: encode error in cmd
*/

char *
mi_rd_cmd(sd, timeout, cmd, rlen, name)
    socket_t sd;
    struct timeval *timeout;
    char *cmd;
    size_t *rlen;
    char *name;
{
    ssize_t len;
    mi_int32 expl;
    ssize_t i;
    FD_RD_VAR(rds, excs);
    int ret;
    int save_errno;
    char *buf;
    char data[MILTER_LEN_BYTES + 1];

    *cmd = '\0';
    *rlen = 0;

    i = 0;
    for (;;)
    {
        FD_RD_INIT(sd, rds, excs);
        ret = FD_RD_READY(sd, rds, excs, timeout);
        if (ret == 0)
            break;
        else if (ret < 0)
        {
            if (errno == EINTR)
                continue;
            break;
        }
        if (FD_IS_RD_EXC(sd, rds, excs))
        {
            *cmd = SMFIC_SELECT;
            return NULL;
        }

        len = MI_SOCK_READ(sd, data + i, sizeof data - i);
        if (MI_SOCK_READ_FAIL(len))
        {
            smi_log(SMI_LOG_ERR,
                "%s, mi_rd_cmd: read returned %d: %s",
                name, (int) len, sm_errstring(errno));
            *cmd = SMFIC_RECVERR;
            return NULL;
        }
        if (len == 0)
        {
            *cmd = SMFIC_EOF;
            return NULL;
        }
        if (len >= (ssize_t) sizeof data - i)
            break;
        i += len;
    }
    if (ret == 0)
    {
        *cmd = SMFIC_TIMEOUT;
        return NULL;
    }
    else if (ret < 0)
    {
        smi_log(SMI_LOG_ERR,
            "%s: mi_rd_cmd: %s() returned %d: %s",
            name, MI_POLLSELECT, ret, sm_errstring(errno));
        *cmd = SMFIC_RECVERR;
        return NULL;
    }

    *cmd = data[MILTER_LEN_BYTES];
    data[MILTER_LEN_BYTES] = '\0';
    (void) memcpy((void *) &expl, (void *) &(data[0]), MILTER_LEN_BYTES);
    expl = ntohl(expl) - 1;
    if (expl <= 0)
        return NULL;
    if (expl > Maxdatasize)
    {
        *cmd = SMFIC_TOOBIG;
        return NULL;
    }
#if _FFR_ADD_NULL
    buf = malloc(expl + 1);
#else /* _FFR_ADD_NULL */
    buf = malloc(expl);
#endif /* _FFR_ADD_NULL */
    if (buf == NULL)
    {
        *cmd = SMFIC_MALLOC;
        return NULL;
    }

    i = 0;
    for (;;)
    {
        FD_RD_INIT(sd, rds, excs);
        ret = FD_RD_READY(sd, rds, excs, timeout);
        if (ret == 0)
            break;
        else if (ret < 0)
        {
            if (errno == EINTR)
                continue;
            break;
        }
        if (FD_IS_RD_EXC(sd, rds, excs))
        {
            *cmd = SMFIC_SELECT;
            free(buf);
            return NULL;
        }
        len = MI_SOCK_READ(sd, buf + i, expl - i);
        if (MI_SOCK_READ_FAIL(len))
        {
            smi_log(SMI_LOG_ERR,
                "%s: mi_rd_cmd: read returned %d: %s",
                name, (int) len, sm_errstring(errno));
            ret = -1;
            break;
        }
        if (len == 0)
        {
            *cmd = SMFIC_EOF;
            free(buf);
            return NULL;
        }
        if (len > expl - i)
        {
            *cmd = SMFIC_RECVERR;
            free(buf);
            return NULL;
        }
        if (len >= expl - i)
        {
            *rlen = expl;
#if _FFR_ADD_NULL
            /* makes life simpler for common string routines */
            buf[expl] = '\0';
#endif /* _FFR_ADD_NULL */
            return buf;
        }
        i += len;
    }

    save_errno = errno;
    free(buf);

    /* select returned 0 (timeout) or < 0 (error) */
    if (ret == 0)
    {
        *cmd = SMFIC_TIMEOUT;
        return NULL;
    }
    if (ret < 0)
    {
        smi_log(SMI_LOG_ERR,
            "%s: mi_rd_cmd: %s() returned %d: %s",
            name, MI_POLLSELECT, ret, sm_errstring(save_errno));
        *cmd = SMFIC_RECVERR;
        return NULL;
    }
    *cmd = SMFIC_UNKNERR;
    return NULL;
}

/*
**  RETRY_WRITEV -- Keep calling the writev() system call
**  until all the data is written out or an error occurs.
**
**  Parameters:
**      fd -- socket descriptor
**      iov -- io vector
**      iovcnt -- number of elements in io vector
**          must NOT exceed UIO_MAXIOV.
**      timeout -- maximum time to wait
**
**  Returns:
**      success: number of bytes written
**      otherwise: MI_FAILURE
*/

static ssize_t
retry_writev(fd, iov, iovcnt, timeout)
    socket_t fd;
    struct iovec *iov;
    int iovcnt;
    struct timeval *timeout;
{
    int i;
    ssize_t n, written;
    FD_WR_VAR(wrs);

    written = 0;
    for (;;)
    {
        while (iovcnt > 0 && iov[0].iov_len == 0)
        {
            iov++;
            iovcnt--;
        }
        if (iovcnt <= 0)
            return written;

        /*
        **  We don't care much about the timeout here,
        **  it's very long anyway; correct solution would be
        **  to take the time before the loop and reduce the
        **  timeout after each invocation.
        **  FD_SETSIZE is checked when socket is created.
        */

        FD_WR_INIT(fd, wrs);
        i = FD_WR_READY(fd, wrs, timeout);
        if (i == 0)
            return MI_FAILURE;
        if (i < 0)
        {
            if (errno == EINTR || errno == EAGAIN)
                continue;
            return MI_FAILURE;
        }
        n = writev(fd, iov, iovcnt);
        if (n == -1)
        {
            if (errno == EINTR || errno == EAGAIN)
                continue;
            return MI_FAILURE;
        }

        written += n;
        for (i = 0; i < iovcnt; i++)
        {
            if (iov[i].iov_len > (unsigned int) n)
            {
                iov[i].iov_base = (char *)iov[i].iov_base + n;
                iov[i].iov_len -= (unsigned int) n;
                break;
            }
            n -= (int) iov[i].iov_len;
            iov[i].iov_len = 0;
        }
        if (i == iovcnt)
            return written;
    }
}

/*
**  MI_WR_CMD -- write a cmd to sd
**
**  Parameters:
**      sd -- socket descriptor
**      timeout -- maximum time to wait
**      cmd -- single character command to write
**      buf -- buffer with further data
**      len -- length of buffer (without cmd!)
**
**  Returns:
**      MI_SUCCESS/MI_FAILURE
*/

int
mi_wr_cmd(sd, timeout, cmd, buf, len)
    socket_t sd;
    struct timeval *timeout;
    int cmd;
    char *buf;
    size_t len;
{
    size_t sl;
    ssize_t l;
    mi_int32 nl;
    int iovcnt;
    struct iovec iov[2];
    char data[MILTER_LEN_BYTES + 1];

    if (len > Maxdatasize || (len > 0 && buf == NULL))
        return MI_FAILURE;

    nl = htonl(len + 1);    /* add 1 for the cmd char */
    (void) memcpy(data, (void *) &nl, MILTER_LEN_BYTES);
    data[MILTER_LEN_BYTES] = (char) cmd;
    sl = MILTER_LEN_BYTES + 1;

    /* set up the vector for the size / command */
    iov[0].iov_base = (void *) data;
    iov[0].iov_len  = sl;
    iovcnt = 1;
    if (len >= 0 && buf != NULL)
    {
        iov[1].iov_base = (void *) buf;
        iov[1].iov_len  = len;
        iovcnt = 2;
    }

    l = retry_writev(sd, iov, iovcnt, timeout);
    if (l == MI_FAILURE)
        return MI_FAILURE;
    return MI_SUCCESS;
}