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Diffstat (limited to 'libnet/src/libnet_build_gre.c')
| -rw-r--r-- | libnet/src/libnet_build_gre.c | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/libnet/src/libnet_build_gre.c b/libnet/src/libnet_build_gre.c new file mode 100644 index 0000000..620c27a --- /dev/null +++ b/libnet/src/libnet_build_gre.c @@ -0,0 +1,399 @@ +/* + * libnet + * libnet_build_gre.c - GRE packet assembler + * + * Copyright (c) 2003 Frédéric Raynal <pappy@security-labs.org> + * 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 + +/* + * Overall packet + * + * The entire encapsulated packet would then have the form: + * + * --------------------------------- + * | | + * | Delivery Header | + * | | + * --------------------------------- + * | | + * | GRE Header | + * | | + * --------------------------------- + * | | + * | Payload packet | + * | | + * --------------------------------- + * + * RFC 1701 defines a header. + * A new RFC (2784) has changed the header and proposed to remove the key + * and seqnum. + * A newer RFC (2890) has changed the header proposed in RFC 2784 by putting + * back key and seqnum. + * These will be supported the day IETF'guys stop this mess ! + * + * FR + */ + + +/* + * Generic Routing Encapsulation (GRE) + * RFC 1701 http://www.faqs.org/rfcs/rfc1701.html + * + * + * Packet header + * + * The GRE packet header has the form: + * + * 0 1 2 3 + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |C|R|K|S|s|Recur| Flags | Ver | Protocol Type | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Checksum (optional) | Offset (optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Key (optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Sequence Number (optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Routing (optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * + * Enhanced GRE header + * + * See rfc 2637 for details. It is used for PPTP tunneling. + * + * 0 1 2 3 + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |C|R|K|S|s|Recur|A| Flags | Ver | Protocol Type | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Key (HW) Payload Length | Key (LW) Call ID | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Sequence Number (Optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Acknowledgment Number (Optional) | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * + */ +#if 0 +static void +__libnet_print_gre_flags_ver(u_int16_t fv) +{ + printf("version = %d (%d) -> ", + fv & GRE_VERSION_MASK, libnet_getgre_length(fv)); + if (fv & GRE_CSUM) + { + printf("CSUM "); + } + if (fv & GRE_ROUTING) + { + printf("ROUTING "); + } + if (fv & GRE_KEY) + { + printf("KEY "); + } + if (fv & GRE_SEQ) + { + printf("SEQ "); + } + if (fv & GRE_ACK) + { + printf("ACK "); + } + printf("\n"); +} +#endif + +/* FIXME: what is the portability of the "((struct libnet_gre_hdr*)0)->" ? */ +u_int32_t +libnet_getgre_length(u_int16_t fv) +{ + + u_int32_t n = LIBNET_GRE_H; + /* + * If either the Checksum Present bit or the Routing Present bit are + * set, BOTH the Checksum and Offset fields are present in the GRE + * packet. + */ + + if ((!(fv & GRE_VERSION_MASK) && (fv & (GRE_CSUM|GRE_ROUTING))) || /* v0 */ + (fv & GRE_VERSION_MASK) ) /* v1 */ + { + n += sizeof( ((struct libnet_gre_hdr *)0)->gre_sum) + + sizeof( ((struct libnet_gre_hdr *)0)->gre_offset); + } + + if ((!(fv & GRE_VERSION_MASK) && (fv & GRE_KEY)) || /* v0 */ + ( (fv & GRE_VERSION_MASK) && (fv & GRE_SEQ)) ) /* v1 */ + { + n += sizeof( ((struct libnet_gre_hdr *)0)->gre_key); + } + + if ((!(fv & GRE_VERSION_MASK) && (fv & GRE_SEQ)) || /* v0 */ + ( (fv & GRE_VERSION_MASK) && (fv & GRE_ACK)) ) /* v1 */ + { + n += sizeof( ((struct libnet_gre_hdr *)0)->gre_seq ); + } + + return (n); +} + +libnet_ptag_t +libnet_build_gre(u_int16_t fv, u_int16_t type, u_int16_t sum, +u_int16_t offset, u_int32_t key, u_int32_t seq, u_int16_t len, +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_gre_hdr gre_hdr; + + if (l == NULL) + { + return (-1); + } + + n = libnet_getgre_length(fv) + payload_s; + + /* + * Find the existing protocol block if a ptag is specified, or create + * a new one. + */ + p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_GRE_H); + if (p == NULL) + { + return (-1); + } + + gre_hdr.flags_ver = htons(fv); + gre_hdr.type = htons(type); + n = libnet_pblock_append(l, p, (u_int8_t *)&gre_hdr, LIBNET_GRE_H); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + + if ((!(fv & GRE_VERSION_MASK) && (fv & (GRE_CSUM|GRE_ROUTING))) || /* v0 */ + (fv & GRE_VERSION_MASK)) /* v1 */ + { + sum = htons(sum); + n = libnet_pblock_append(l, p, (u_int8_t*)&sum, + sizeof(gre_hdr.gre_sum)); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + offset = htons(offset); + n = libnet_pblock_append(l, p, (u_int8_t*)&offset, + sizeof(gre_hdr.gre_offset)); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + } + + if ((!(fv & GRE_VERSION_MASK) && (fv & GRE_KEY)) || /* v0 */ + ( (fv & GRE_VERSION_MASK) && (fv & GRE_SEQ)) ) /* v1 */ + { + key = htonl(key); + n = libnet_pblock_append(l, p, (u_int8_t*)&key, + sizeof(gre_hdr.gre_key)); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + } + + if ((!(fv & GRE_VERSION_MASK) && (fv & GRE_SEQ)) || /* v0 */ + ( (fv & GRE_VERSION_MASK) && (fv & GRE_ACK)) ) /* v1 */ + { + seq = htonl(seq); + n = libnet_pblock_append(l, p, (u_int8_t*)&seq, + sizeof(gre_hdr.gre_seq)); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + } + + /* boilerplate payload sanity check / append macro */ + LIBNET_DO_PAYLOAD(l, p); + + if ( (fv & GRE_CSUM) && (!sum) ) + { + libnet_pblock_setflags(p, LIBNET_PBLOCK_DO_CHECKSUM); + } + + return (ptag ? ptag : libnet_pblock_update(l, p, len, LIBNET_PBLOCK_GRE_H)); + +bad: + libnet_pblock_delete(l, p); + return (-1); +} + +libnet_ptag_t +libnet_build_egre(u_int16_t fv, u_int16_t type, u_int16_t sum, +u_int16_t offset, u_int32_t key, u_int32_t seq, u_int16_t len, +u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag) +{ + return (libnet_build_gre(fv, type, sum, offset, key, seq, len, + payload, payload_s, l, ptag)); +} + +/* + * Routing (variable) + * + * The Routing field is optional and is present only if the Routing + * Present bit is set to 1. + * + * The Routing field is a list of Source Route Entries (SREs). Each + * SRE has the form: + * + * 0 1 2 3 + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Address Family | SRE Offset | SRE Length | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | Routing Information ... + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * + */ +libnet_ptag_t +libnet_build_gre_sre(u_int16_t af, u_int8_t offset, u_int8_t length, +u_int8_t *routing, 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_gre_sre_hdr sre_hdr; + + if (l == NULL) + { + return (-1); + } + + n = LIBNET_GRE_SRE_H + length + payload_s; + + /* + * Find the existing protocol block if a ptag is specified, or create + * a new one. + */ + p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_GRE_SRE_H); + if (p == NULL) + { + return (-1); + } + sre_hdr.af = htons(af); + sre_hdr.sre_offset = offset; + sre_hdr.sre_length = length; + n = libnet_pblock_append(l, p, (u_int8_t *)&sre_hdr, LIBNET_GRE_SRE_H); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + + if ((routing && !length) || (!routing && length)) + { + sprintf(l->err_buf, "%s(): routing inconsistency\n", __func__); + goto bad; + } + + if (routing && length) + { + n = libnet_pblock_append(l, p, routing, length); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + } + + /* boilerplate payload sanity check / append macro */ + LIBNET_DO_PAYLOAD(l, p); + + return (ptag ? ptag : libnet_pblock_update(l, p, 0, + LIBNET_PBLOCK_GRE_SRE_H)); + +bad: + libnet_pblock_delete(l, p); + return (-1); + +} + +libnet_ptag_t +libnet_build_gre_last_sre(libnet_t *l, libnet_ptag_t ptag) +{ + u_int32_t n, zero = 0; + libnet_pblock_t *p; + + if (l == NULL) + { + return (-1); + } + + n = LIBNET_GRE_SRE_H; + + /* + * Find the existing protocol block if a ptag is specified, or create + * a new one. + */ + p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_GRE_H); + if (p == NULL) + { + return (-1); + } + + n = libnet_pblock_append(l, p, (u_int8_t *)&zero, LIBNET_GRE_SRE_H); + if (n == -1) + { + /* err msg set in libnet_pblock_append() */ + goto bad; + } + + return (ptag ? ptag : libnet_pblock_update(l, p, 0, + LIBNET_PBLOCK_GRE_SRE_H)); + +bad: + libnet_pblock_delete(l, p); + return (-1); + +} +/* EOF */ |