libnet_build_ip.c

tcp数据流重放工具

    {
        return (-1);
    }
	
	memset(&ip_hdr, 0, sizeof(ip_hdr));
	ip_hdr.ip_v          = 4;                         /* version 4 */
    ip_hdr.ip_hl         = 5;                         /* 20 byte header */

    /* check to see if there are IP options to include */
    if (p->prev)
    {
        if (p->prev->type == LIBNET_PBLOCK_IPO_H)
        {
            /*
             *  Count up number of 32-bit words in options list, padding if
             *  neccessary.
             */
            for (i = 0, j = 0; i < p->prev->b_len; i++)
            {
                (i % 4) ? j : j++;
            }
            ip_hdr.ip_hl += j;
        }
    }

    ip_hdr.ip_tos        = 0;                         /* IP tos */
    ip_hdr.ip_len        = htons(h);                  /* total length */
    ip_hdr.ip_id         = htons((l->ptag_state) & 0x0000ffff); /* IP ID */
    ip_hdr.ip_off        = 0;                         /* fragmentation flags */
    ip_hdr.ip_ttl        = 64;                        /* time to live */
    ip_hdr.ip_p          = prot;                      /* transport protocol */
    ip_hdr.ip_sum        = 0;                         /* checksum */
    ip_hdr.ip_src.s_addr = src;                       /* source ip */
    ip_hdr.ip_dst.s_addr = dst;                       /* destination ip */

    n = libnet_pblock_append(l, p, (u_int8_t *)&ip_hdr, LIBNET_IPV4_H);
    if (n == -1)
    {
        goto bad;
    }

    libnet_pblock_setflags(p, LIBNET_PBLOCK_DO_CHECKSUM);
    return (libnet_pblock_update(l, p, LIBNET_IPV4_H, LIBNET_PBLOCK_IPV4_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}

libnet_ptag_t
libnet_build_ipv4_options(u_int8_t *options, u_int32_t options_s, libnet_t *l, 
        libnet_ptag_t ptag)
{
    int offset, underflow;
    u_int32_t i, j, n, adj_size;
    libnet_pblock_t *p, *p_temp;
    struct libnet_ipv4_hdr *ip_hdr;

    if (l == NULL)
    { 
        return (-1);
    }

    underflow = 0;
    offset = 0;

    /* check options list size */
    if (options_s > LIBNET_MAXOPTION_SIZE)
    {
        snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
            "%s(): options list is too large %d\n", __func__, options_s);
        return (-1);
    }

    adj_size = options_s;
    if (adj_size % 4)
    {
        /* size of memory block with padding */
        adj_size += 4 - (options_s % 4);
    }

    /* if this pblock already exists, determine if there is a size diff */
    if (ptag)
    {
        p_temp = libnet_pblock_find(l, ptag);
        if (p_temp)
        {
            if (adj_size >= p_temp->b_len)
            {                                   
                offset = adj_size - p_temp->b_len;                             
            }
            else
            {                                                           
                offset = p_temp->b_len - adj_size;                             
                underflow = 1;
            }
        }
        else
        {
            /* 
             * XXX - When this completes successfully, libnet errbuf contains 
             * an error message so to come correct, we'll clear it.
             */ 
            memset(l->err_buf, 0, sizeof (l->err_buf));
        }
    }

    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, adj_size, LIBNET_PBLOCK_IPO_H);
    if (p == NULL)
    {
        return (-1);
    }

    /* append options */
    n = libnet_pblock_append(l, p, options, options_s);
    if (n == -1)
    {
        goto bad;
    }

    /* append padding */
    n = libnet_pblock_append(l, p, "\0\0\0", adj_size - options_s);
    if (n == -1)
    {
        goto bad;
    }

    if (ptag && p->next)
    {
        p_temp = p->next;
        while ((p_temp->next) && (p_temp->type != LIBNET_PBLOCK_IPV4_H))
        {
            p_temp = p_temp->next;
        }

        /* fix the IP header size */
        if (p_temp->type == LIBNET_PBLOCK_IPV4_H)
        {
            /*
             *  Count up number of 32-bit words in options list, padding if
             *  neccessary.
             */
            for (i = 0, j = 0; i < p->b_len; i++)
            {
                (i % 4) ? j : j++;
            }
            ip_hdr = (struct libnet_ipv4_hdr *) p_temp->buf;
            ip_hdr->ip_hl = j + 5;

            if (!underflow)
            {
                p_temp->h_len += offset;
            }
            else
            {
                p_temp->h_len -= offset;
            }
        }
    }

    return (ptag ? ptag : libnet_pblock_update(l, p, adj_size,
            LIBNET_PBLOCK_IPO_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}

libnet_ptag_t
libnet_build_ipv6(u_int8_t tc, u_int32_t fl, u_int16_t len, u_int8_t nh, u_int8_t hl,
            struct libnet_in6_addr src, struct libnet_in6_addr dst,
            u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{   
    u_int32_t n;
    libnet_pblock_t *p;
    struct libnet_ipv6_hdr ip_hdr;

    if (l == NULL)
    {
        return (-1);
    }

    n = LIBNET_IPV6_H + payload_s;          /* size of memory block */
       
    if (LIBNET_IPV6_H + payload_s > IP_MAXPACKET)
    {  
         snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
			     "%s(): IP packet too large\n", __func__);
        return (-1);
    }  
       
    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_IPV6_H);
    if (p == NULL)
    {   
        return (-1);
    }  
    
	memset(&ip_hdr, 0, sizeof(ip_hdr));
	ip_hdr.ip_flags[0] =  0x06 << 4;
    ip_hdr.ip_flags[1] = 0;
    ip_hdr.ip_flags[2] = 0;
    ip_hdr.ip_flags[3] = 0;
    /* XXX: TODO: traffic class, flow label */
    ip_hdr.ip_len      = htons(len);
    ip_hdr.ip_nh       = nh;
    ip_hdr.ip_hl       = hl;
    ip_hdr.ip_src      = src;
    ip_hdr.ip_dst      = dst;
     
    n = libnet_pblock_append(l, p, (u_int8_t *)&ip_hdr, LIBNET_IPV6_H);
    if (n == -1)
    {
        goto bad;
    }

    if ((payload && !payload_s) || (!payload && payload_s))
    {
         snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
			     "%s(): payload inconsistency\n", __func__);
        goto bad;
    }
 
    if (payload && payload_s)
    {  
        n = libnet_pblock_append(l, p, payload, payload_s);
        if (n == -1)
        {
            goto bad;
        }
    }

    /* no checksum for IPv6 */
    return (ptag ? ptag : libnet_pblock_update(l, p, LIBNET_IPV6_H,
            LIBNET_PBLOCK_IPV6_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}

libnet_ptag_t
libnet_autobuild_ipv6(u_int16_t len, u_int8_t nh, struct libnet_in6_addr dst,
            libnet_t *l)
{

    /* NYI */
     snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
		     "%s(): not yet implemented\n", __func__);
    return (-1);

#if 0
    struct libnet_in6_addr src = libnet_get_ipaddr6(l);

    if (strncmp((int8_t*)&src, (int8_t*)&in6addr_error, sizeof(in6addr_error)) == 0)
    {
        return (-1);
    }

    return (libnet_build_ipv6(0, 0, len, nh, 64, src, dst, NULL, 0, l, 0));
#endif
}

/* EOF */