conduit.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: a17f14f905d184bf05cf64066dff72a11de89e6b $
 *
 * @file conduit.c
 * @brief Channels for communicating with radmin
 *
 * @copyright 2015 The FreeRADIUS server project
 * @copyright 2015 Alan DeKok (aland@deployingradius.com)
 */
RCSID("$Id: a17f14f905d184bf05cf64066dff72a11de89e6b $")
 
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/math.h>
#include <freeradius-devel/util/strerror.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "conduit.h"
 
static ssize_t lo_read(int fd, void *out, size_t outlen)
{
        ssize_t total;
        ssize_t r;
        uint8_t *p = out;
 
        for (total = 0; (size_t)total < outlen; ) {
                r = read(fd, p + total, outlen - total);
                if (r == 0) return total;
 
                if (r < 0) {
                        switch (errno) {
                        case EINTR:
                                continue;
 
#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN)
                        case EWOULDBLOCK:
#endif
                        case EAGAIN:
                                return total;
 
                        default:
                                break;
                        }
 
                        return -1;
                }
 
                /*
                 *      The total never exceeds outlen, which is far below
                 *      SSIZE_MAX.
                 */
                if (!fr_cond_assert(fr_add(&total, total, r))) return -1;
        }
 
        return total;
}
 
 
/*
 *      A non-blocking copy of fr_conduit_read().
 */
ssize_t fr_conduit_read_async(int fd, fr_conduit_type_t *pconduit,
                              void *out, size_t outlen, size_t *leftover, bool *want_more)
{
        ssize_t r;
        uint32_t data_len;
        uint8_t *buffer = out;
        fr_conduit_hdr_t hdr;
        size_t offset = *leftover;
 
        /*
         *      If we can't even read a header, die.
         */
        if (outlen <= sizeof(hdr)) {
                errno = EINVAL;
                return -1;
        }
 
        *want_more = true;
 
        /*
         *      Ensure that we read the header first.
         */
        if (offset < sizeof(hdr)) {
                r = lo_read(fd, buffer + offset, sizeof(hdr) - offset);
                if (r <= 0) return r;
 
                *leftover += r;
                offset += r;
 
                /*
                 *      We have leftover data, but no *packet* to
                 *      return.
                 */
                if (offset < sizeof(hdr)) return 0;
        }
 
        /*
         *      We've read the header.  Figure out how much more data
         *      we need to read.
         */
        memcpy(&hdr, buffer, sizeof(hdr));
        data_len = ntohl(hdr.length);
 
        /*
         *      The data will overflow the buffer.  Die.  outlen is larger
         *      than the header, see above, so the subtraction can't wrap,
         *      and data_len from the wire is checked before any arithmetic
         *      uses it.
         */
        if (data_len > (outlen - sizeof(hdr))) {
                errno = EINVAL;
                return -1;
        }
 
        /*
         *      This is how much we really want.
         */
        outlen = sizeof(hdr) + data_len;
 
        r = lo_read(fd, buffer + offset, outlen - offset);
        if (r <= 0) return r;
 
        offset += r;
 
        if (offset == outlen) {
                uint16_t conduit = ntohs(hdr.conduit);
 
                *want_more = false;
                *pconduit = (fr_conduit_type_t) conduit;
                return outlen;
        }
 
        *leftover = offset;
        return 0;
}
 
ssize_t fr_conduit_read(int fd, fr_conduit_type_t *pconduit, void *out, size_t outlen)
{
        ssize_t r;
        size_t data_len;
        uint8_t *buffer = out;
        fr_conduit_hdr_t hdr;
        uint16_t conduit;
 
        /*
         *      Read the header
         */
        r = lo_read(fd, &hdr, sizeof(hdr));
        if (r <= 0) return r;
 
        /*
         *      Read the data into the buffer.
         */
        conduit = ntohs(hdr.conduit);
        *pconduit = (fr_conduit_type_t) conduit;
        data_len = ntohl(hdr.length);
        if (data_len == 0) return 0;
        if (data_len > UINT32_MAX) data_len = UINT32_MAX;       /* For Coverity */
 
#if 0
        fprintf(stderr, "CONDUIT R %zu length %zu\n", *pconduit, data_len);
#endif
 
        /*
         *      Shrink the output buffer to the size of the data we
         *      have.
         */
        if (outlen > data_len) outlen = data_len;
 
        r = lo_read(fd, buffer, outlen);
        if (r <= 0) return r;
 
        /*
         *      Read and discard any extra data sent to us.  Sorry,
         *      caller, you should have used a larger buffer!
         */
        while (data_len > outlen) {
                size_t discard;
                uint8_t junk[64];
 
                discard = data_len - outlen;
                if (discard > sizeof(junk)) discard = sizeof(junk);
 
                r = lo_read(fd, junk, discard);
                if (r <= 0) break;
 
                data_len -= r;
        }
 
        return outlen;
}
 
static ssize_t lo_write(int fd, void const *out, size_t outlen)
{
        size_t total;
        ssize_t r;
        uint8_t const *buffer = out;
 
        total = outlen;
 
        while (total > 0) {
                r = write(fd, buffer, total);
                if (r == 0) {
                        errno = EAGAIN;
                        return -1;
                }
 
                if (r < 0) {
                        if (errno == EINTR) continue;
 
                        return -1;
                }
 
                buffer += r;
                total -= r;
        }
 
        return outlen;
}
 
ssize_t fr_conduit_write(int fd, fr_conduit_type_t conduit, void const *out, size_t outlen)
{
        ssize_t r;
        fr_conduit_hdr_t hdr;
        uint8_t const *buffer = out;
 
        if (outlen > UINT32_MAX) {
                fr_strerror_printf("Data to write to conduit (%zu bytes) exceeds maximum length", outlen);
                return -1;
        }
 
        /*
         *      Asked to write nothing, suppress it.
         */
        if (!outlen) return 0;
 
        hdr = (fr_conduit_hdr_t) {
                .conduit = htons(conduit),
                .length = htonl(outlen),
        };
 
#if 0
        fprintf(stderr, "CONDUIT W %zu length %zu\n", conduit, outlen);
#endif
 
        /*
         *      write the header
         */
        r = lo_write(fd, &hdr, sizeof(hdr));
        if (r <= 0) return r;
 
        /*
         *      write the data directly from the buffer
         */
        r = lo_write(fd, buffer, outlen);
        if (r <= 0) return r;
 
        return outlen;
}