githubmirror/libnet

src/libnet_pblock.c
623 строки17 KB
Joachim Nilsson
Add coding style hinting for Emacs
08 окт 2019, 22:00
08 окт 2019, 22:00f11fcc1
/*
 *  $Id: libnet_pblock.c,v 1.14 2004/11/09 07:05:07 mike Exp $
 *
 *  libnet
 *  libnet_pblock.c - Memory protocol block routines.
 *
 *  Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
 *  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include "common.h"
#include <assert.h>

libnet_pblock_t *
libnet_pblock_probe(libnet_t *l, libnet_ptag_t ptag, uint32_t b_len, uint8_t type)
{
    int offset;
    libnet_pblock_t *p;

    if (ptag == LIBNET_PTAG_INITIALIZER)
    {
        return libnet_pblock_new(l, b_len);
    }

    /*
     *  Update this pblock, don't create a new one.  Note that if the
     *  new packet size is larger than the old one we will do a malloc.
     */
    p = libnet_pblock_find(l, ptag);

    if (p == NULL)
    {
        /* err msg set in libnet_pblock_find() */
        return (NULL);
    }
    if (p->type != type)
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                "%s(): ptag refers to different type than expected (0x%x != 0x%x)",
                __func__, p->type, type);
        return (NULL); 
    }
    /*
     *  If size is greater than the original block of memory, we need 
     *  to malloc more memory.  Should we use realloc?
     */
    if (b_len > p->b_len)
    {
        offset = b_len - p->b_len;  /* how many bytes larger new pblock is */
        free(p->buf);
        p->buf = malloc(b_len);
        if (p->buf == NULL)
        {
            snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                    "%s(): can't resize pblock buffer: %s", __func__,
                    strerror(errno));
            return (NULL);
        }
        memset(p->buf, 0, b_len);
        p->h_len += offset; /* new length for checksums */
        p->b_len = b_len;       /* new buf len */
        l->total_size += offset;
    }
    else
    {
        offset = p->b_len - b_len;
        p->h_len -= offset; /* new length for checksums */
        p->b_len = b_len;       /* new buf len */
        l->total_size -= offset;
    }
    p->copied = 0;      /* reset copied counter */

    return (p);
}

static void* zmalloc(libnet_t* l, uint32_t size, const char* func)
{
    void* v = malloc(size);
    if(v)
        memset(v, 0, size);
    else
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, "%s(): malloc(): %s", func, 
                strerror(errno));
    return v;
}

libnet_pblock_t *
libnet_pblock_new(libnet_t *l, uint32_t b_len)
{
    libnet_pblock_t *p = zmalloc(l, sizeof(libnet_pblock_t), __func__);
    if(!p)
        return NULL;

    p->buf = zmalloc(l, b_len, __func__);

    if(!p->buf)
    {
        free(p);
        return NULL;
    }

    p->b_len = b_len;

    l->total_size += b_len;
    l->n_pblocks++;

    /* make the head node if it doesn't exist */
    if (l->protocol_blocks == NULL)
    {
        l->protocol_blocks = p;
        l->pblock_end = p;
    }
    else
    {
        l->pblock_end->next = p;
        p->prev = l->pblock_end;
        l->pblock_end = p;
    }

    return p;
}

int
libnet_pblock_swap(libnet_t *l, libnet_ptag_t ptag1, libnet_ptag_t ptag2)
{
    libnet_pblock_t *p1, *p2;

    p1 = libnet_pblock_find(l, ptag1);
    p2 = libnet_pblock_find(l, ptag2);
    if (p1 == NULL || p2 == NULL)
    {
        /* error set elsewhere */
        return (-1);
    }

    p2->prev = p1->prev;
    p1->next = p2->next;
    p2->next = p1;
    p1->prev = p2;

    if (p1->next)
    {
        p1->next->prev = p1;
    }

    if (p2->prev)
    {
        p2->prev->next = p2;
    }
    else
    {
        /* first node on the list */
        l->protocol_blocks = p2;
    }

    if (l->pblock_end == p2)
    {
        l->pblock_end = p1;
    }
    return (1);
}

static void libnet_pblock_remove_from_list(libnet_t *l, libnet_pblock_t *p)
{
    if (p->prev) 
    {
        p->prev->next = p->next;
    }
    else
    {
        l->protocol_blocks = p->next;
    }

    if (p->next)
    {
        p->next->prev = p->prev;
    }
    else
    {
        l->pblock_end = p->prev;
    }
}

int
libnet_pblock_insert_before(libnet_t *l, libnet_ptag_t ptag1,
        libnet_ptag_t ptag2)
{
    libnet_pblock_t *p1, *p2;

    p1 = libnet_pblock_find(l, ptag1);
    p2 = libnet_pblock_find(l, ptag2);
    if (p1 == NULL || p2 == NULL)
    {
        /* error set elsewhere */
        return (-1);
    }

    /* check for already present before */
    if(p2->next == p1)
        return 1;

    libnet_pblock_remove_from_list(l, p2);

    /* insert p2 into list */
    p2->prev = p1->prev;
    p2->next = p1;
    p1->prev = p2;

    if (p2->prev)  
    {
        p2->prev->next = p2;
    }
    else
    {
        /* first node on the list */
        l->protocol_blocks = p2;
    }
    
    return (1);
}

libnet_pblock_t *
libnet_pblock_find(libnet_t *l, libnet_ptag_t ptag)
{
    libnet_pblock_t *p;

    for (p = l->protocol_blocks; p; p = p->next)
    {
        if (p->ptag == ptag)
        {
            return (p); 
        }
    }
    snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
            "%s(): couldn't find protocol block", __func__);
    return (NULL);
}

int
libnet_pblock_append(libnet_t *l, libnet_pblock_t *p, const void *buf, uint32_t len)
{
    if (len && !buf)
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
			    "%s(): payload inconsistency", __func__);
        return -1;
    }

    if (p->copied + len > p->b_len)
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                "%s(): memcpy would overflow buffer", __func__);
        return (-1);
    }
    memcpy(p->buf + p->copied, buf, len);
    p->copied += len;
    return (1);
}

void
libnet_pblock_setflags(libnet_pblock_t *p, uint8_t flags)
{
    p->flags = flags;
}

/* FIXME both ptag setting and end setting should be done in pblock new and/or pblock probe. */
libnet_ptag_t
libnet_pblock_update(libnet_t *l, libnet_pblock_t *p, uint32_t h_len, uint8_t type)
{
    p->type  =  type;
    p->ptag  =  ++(l->ptag_state);
    p->h_len = h_len;
    l->pblock_end = p;              /* point end of pblock list here */

    return (p->ptag);
}

static int pblock_is_ip(libnet_pblock_t* p)
{
    return p->type == LIBNET_PBLOCK_IPV4_H || p->type == LIBNET_PBLOCK_IPV6_H;
}

/* q is either an ip hdr, or is followed  by an ip hdr. return the offset
 * from end of packet. if there is no offset, we'll return the total size,
 * and things will break later
 */
static int calculate_ip_offset(libnet_t* l, libnet_pblock_t* q)
{
    int ip_offset = 0;
    libnet_pblock_t* p = l->protocol_blocks;
    for(; p && p != q; p = p->next) {
	ip_offset += p->b_len;
    }
    assert(p == q); /* if not true, then q is not a pblock! */

    for(; p; p = p->next) {
	ip_offset += p->b_len;
	if(pblock_is_ip(p))
	    break;
    }

    return ip_offset;
}

int
libnet_pblock_coalesce(libnet_t *l, uint8_t **packet, uint32_t *size)
{
    /*
     *  Determine the offset required to keep memory aligned (strict
     *  architectures like solaris enforce this, but's a good practice
     *  either way).  This is only required on the link layer with the
     *  14 byte ethernet offset (others are similarly unkind).
     */
    if (l->injection_type == LIBNET_LINK || 
        l->injection_type == LIBNET_LINK_ADV)
    {
        /* 8 byte alignment should work */
        l->aligner = 8 - (l->link_offset % 8);
    }
    else
    {
        l->aligner = 0;
    }

    if(!l->total_size && !l->aligner) {
        /* Avoid allocating zero bytes of memory, it perturbs electric fence. */
        *packet = malloc(1);
        **packet =1;
    } else {
        *packet = malloc(l->aligner + l->total_size);
    }
    if (*packet == NULL)
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, "%s(): malloc(): %s",
                __func__, strerror(errno));
        return (-1);
    }

    memset(*packet, 0, l->aligner + l->total_size);

    if (l->injection_type == LIBNET_RAW4 && 
        l->pblock_end->type == LIBNET_PBLOCK_IPV4_H)
    {
        libnet_pblock_setflags(l->pblock_end, LIBNET_PBLOCK_DO_CHECKSUM); 
    }
    
    /* additional sanity checks to perform if we're not in advanced mode */
    if (!(l->injection_type & LIBNET_ADV_MASK))
    {
    	switch (l->injection_type)
    	{
            case LIBNET_LINK:
                if ((l->pblock_end->type != LIBNET_PBLOCK_TOKEN_RING_H) &&
                    (l->pblock_end->type != LIBNET_PBLOCK_FDDI_H)       &&
                    (l->pblock_end->type != LIBNET_PBLOCK_ETH_H)        &&
                    (l->pblock_end->type != LIBNET_PBLOCK_802_1Q_H)     &&
                    (l->pblock_end->type != LIBNET_PBLOCK_ISL_H)        &&
                    (l->pblock_end->type != LIBNET_PBLOCK_802_3_H))
                {
                    snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, 
                    "%s(): packet assembly cannot find a layer 2 header",
                    __func__);
                    goto err;
                }
                break;
            case LIBNET_RAW4:
                if ((l->pblock_end->type != LIBNET_PBLOCK_IPV4_H))
                {
                    snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, 
                    "%s(): packet assembly cannot find an IPv4 header",
                     __func__);
                    goto err;
                }
                break;
            case LIBNET_RAW6:
                if ((l->pblock_end->type != LIBNET_PBLOCK_IPV6_H))
                {
                    snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, 
                    "%s(): packet assembly cannot find an IPv6 header",
                     __func__);
                    goto err;
                }
                break;
            default:
                /* we should not end up here ever */
                snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, 
                "%s(): suddenly the dungeon collapses -- you die",
                 __func__);
                goto err;
            break;
        }
    }

    /* Build packet from end to start. */
    {
        /*
           From top to bottom, go through pblocks pairwise:

           p   is the currently being copied pblock, and steps through every block
           q   is the prev pblock to p that needs checksumming, it will
               not step through every block as p does, it will skip any that do not
               need checksumming.
           n   offset from start of packet to beginning of block we are writing

           q is NULL on first iteration
           p is NULL on last iteration

           Checksums are done on q, to give p a chance to be copied over, since
           checksumming q can require a lower-level header to be encoded, in the
           case of IP protocols (which are the only kinds handled by libnet's
           checksum implementation).

           This is very obscure, or would be much more clear if it was done in
           two loops.
           */
        libnet_pblock_t *q = NULL;
        libnet_pblock_t *p = NULL;
        uint32_t n;

        for (n = l->aligner + l->total_size, p = l->protocol_blocks; p || q; )
        {
            if (q)
            {
                p = p->next;
            }
            if (p)
            {
                n -= p->b_len;
                /* copy over the packet chunk */
                memcpy(*packet + n, p->buf, p->b_len);
            }
#if 0
            printf("-- n %d/%d cksum? %d\n", n, l->aligner + l->total_size,
                    q &&
                    (p == NULL || (p->flags & LIBNET_PBLOCK_DO_CHECKSUM)) &&
                    (q->flags & LIBNET_PBLOCK_DO_CHECKSUM));
            if(q)
            {
                printf(" iph %d/%d offset -%d\n",
                        (l->total_size + l->aligner) - q->ip_offset,
                        l->total_size + l->aligner,
                        q->ip_offset
                      );
            }
            if (p)
            {
                printf("p %p ptag %d b_len %d h_len %d cksum? %d type %s\n",
                        p, p->ptag,
                        p->b_len, p->h_len,
                        p->flags & LIBNET_PBLOCK_DO_CHECKSUM,
                        libnet_diag_dump_pblock_type(p->type)
                      );
            }
            if (q)
            {
                printf("q %p ptag %d b_len %d h_len %d cksum? %d type %s\n",
                        q, q->ptag,
                        q->b_len, q->h_len,
                        q->flags & LIBNET_PBLOCK_DO_CHECKSUM,
                        libnet_diag_dump_pblock_type(q->type)
                      );
            }
#endif
            if (q)
            {
                if (p == NULL || (p->flags & LIBNET_PBLOCK_DO_CHECKSUM))
                {
                    if (q->flags & LIBNET_PBLOCK_DO_CHECKSUM)
                    {
                        uint32_t c;
                        uint8_t* end = *packet + l->aligner + l->total_size;
                        uint8_t* beg = *packet + n;
                        int ip_offset = calculate_ip_offset(l, q);
                        uint8_t* iph = end - ip_offset;
#if 0
			printf("p %d/%s q %d/%s offset calculated %d\n",
				p ? p->ptag : -1, p ? libnet_diag_dump_pblock_type(p->type) : "nil",
				q->ptag, libnet_diag_dump_pblock_type(q->type),
				ip_offset);
#endif
                        c = libnet_inet_checksum(l, iph,
                                libnet_pblock_p2p(q->type), q->h_len,
                                beg, end);
                        if (c == -1)
                        {
                            /* err msg set in libnet_do_checksum() */
                            goto err;
                        }
                    }
                    q = p;
                }
            }
            else
            {
                q = p;
            }
        }
    }
    *size = l->aligner + l->total_size;

    /*
     *  Set the packet pointer to the true beginning of the packet and set
     *  the size for transmission.
     */
    if ((l->injection_type == LIBNET_LINK ||
        l->injection_type == LIBNET_LINK_ADV) && l->aligner)
    {
        *packet += l->aligner;
        *size -= l->aligner;
    }
    return (1);

err:
    free(*packet);
    *packet = NULL;
    return (-1);
}

void
libnet_pblock_delete(libnet_t *l, libnet_pblock_t *p)
{
    if (p)
    {
        l->total_size -= p->b_len;
        l->n_pblocks--;

        libnet_pblock_remove_from_list(l, p);

        if (p->buf)
        {
            free(p->buf);
            p->buf = NULL;
        }

        free(p);
    }
}

int
libnet_pblock_p2p(uint8_t type)
{
    /* for checksum; return the protocol number given a pblock type*/
    switch (type)
    {
        case LIBNET_PBLOCK_CDP_H:
            return (LIBNET_PROTO_CDP);
        case LIBNET_PBLOCK_ICMPV4_H:
        case LIBNET_PBLOCK_ICMPV4_ECHO_H:
        case LIBNET_PBLOCK_ICMPV4_MASK_H:
        case LIBNET_PBLOCK_ICMPV4_UNREACH_H:
        case LIBNET_PBLOCK_ICMPV4_TIMXCEED_H:
        case LIBNET_PBLOCK_ICMPV4_REDIRECT_H:
        case LIBNET_PBLOCK_ICMPV4_TS_H:
            return (IPPROTO_ICMP);
        case LIBNET_PBLOCK_ICMPV6_H:
        case LIBNET_PBLOCK_ICMPV6_ECHO_H:
        case LIBNET_PBLOCK_ICMPV6_UNREACH_H:
        case LIBNET_PBLOCK_ICMPV6_NDP_NSOL_H:
        case LIBNET_PBLOCK_ICMPV6_NDP_NADV_H:
            return (IPPROTO_ICMPV6);
        case LIBNET_PBLOCK_IGMP_H:
            return (IPPROTO_IGMP);
        case LIBNET_PBLOCK_IPV4_H:
            return (IPPROTO_IP);
        case LIBNET_PBLOCK_IPV6_H:
            return (IPPROTO_IPV6);
        case LIBNET_ISL_H:
            return (LIBNET_PROTO_ISL);
        case LIBNET_PBLOCK_OSPF_H:
            return (IPPROTO_OSPF);
        case LIBNET_PBLOCK_LS_RTR_H:
            return (IPPROTO_OSPF_LSA);
        case LIBNET_PBLOCK_TCP_H:
            return (IPPROTO_TCP);
        case LIBNET_PBLOCK_UDP_H:
            return (IPPROTO_UDP);
        case LIBNET_PBLOCK_VRRP_H:
            return (IPPROTO_VRRP);
        case LIBNET_PBLOCK_GRE_H:
            return (IPPROTO_GRE);
        default:
            return (-1);
    }
}

void
libnet_pblock_record_ip_offset(libnet_t *l, libnet_pblock_t *p)
{
    (void) l;
    (void) p;
    /* For backwards compatibility, libnet_pblock_t no longer includes
       an ip_offset, so calling this is unnecessary.
       */
}

/**
 * Local Variables:
 *  indent-tabs-mode: nil
 *  c-file-style: "stroustrup"
 * End:
 */