diff options
Diffstat (limited to 'libnet/src/libnet_build_dns.c')
| -rw-r--r-- | libnet/src/libnet_build_dns.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/libnet/src/libnet_build_dns.c b/libnet/src/libnet_build_dns.c new file mode 100644 index 0000000..fd88619 --- /dev/null +++ b/libnet/src/libnet_build_dns.c @@ -0,0 +1,116 @@ +/* + * $Id: libnet_build_dns.c,v 1.10 2004/04/13 17:32:28 mike Exp $ + * + * libnet + * libnet_build_dns.c - DNS packet assembler + * + * 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. + * + */ + +#if (HAVE_CONFIG_H) +#include "../include/config.h" +#endif +#if (!(_WIN32) || (__CYGWIN__)) +#include "../include/libnet.h" +#else +#include "../include/win32/libnet.h" +#endif + + +libnet_ptag_t +libnet_build_dnsv4(u_int16_t h_len, u_int16_t id, u_int16_t flags, + u_int16_t num_q, u_int16_t num_anws_rr, u_int16_t num_auth_rr, + u_int16_t num_addi_rr, u_int8_t *payload, u_int32_t payload_s, + libnet_t *l, libnet_ptag_t ptag) +{ + + u_int32_t n, h; + u_int offset; + libnet_pblock_t *p; + struct libnet_dnsv4_hdr dns_hdr; + + if (l == NULL) + { + return (-1); + } + + if (h_len != LIBNET_UDP_DNSV4_H && h_len != LIBNET_TCP_DNSV4_H) + { + snprintf(l->err_buf, LIBNET_ERRBUF_SIZE, + "%s(): invalid header length: %d", __func__, h_len); + return (-1); + } + offset = (h_len == LIBNET_UDP_DNSV4_H ? sizeof(dns_hdr.h_len) : 0); + n = h_len + payload_s; + h = 0; /* no checksum */ + + /* + * Find the existing protocol block if a ptag is specified, or create + * a new one. + */ + p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_DNSV4_H); + if (p == NULL) + { + return (-1); + } + + /* + * The sizeof(dns_hdr.h_len) is not counted is the packet size + * for TCP packet. + * And since this will be ignored for udp packets, let's compute it + * anyway. + */ + memset(&dns_hdr, 0, sizeof(dns_hdr)); + dns_hdr.h_len = htons(n - sizeof (dns_hdr.h_len)); + dns_hdr.id = htons(id); + dns_hdr.flags = htons(flags); + dns_hdr.num_q = htons(num_q); + dns_hdr.num_answ_rr = htons(num_anws_rr); + dns_hdr.num_auth_rr = htons(num_auth_rr); + dns_hdr.num_addi_rr = htons(num_addi_rr); + + /* + * A dirty trick: DNS can be either TCP or UDP based, and depending on + * that, the header changes. A 'length' field is present in TCP packets, + * but not in UDP packets. As they are the first 2 bytes of the header, + * they are skipped if the packet is UDP... + */ + n = libnet_pblock_append(l, p, ((u_int8_t *)&dns_hdr) + offset, h_len); + if (n == -1) + { + goto bad; + } + + /* boilerplate payload sanity check / append macro */ + LIBNET_DO_PAYLOAD(l, p); + + return (ptag ? ptag : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_DNSV4_H)); +bad: + libnet_pblock_delete(l, p); + return (-1); +} + +/* EOF */ |