/* Parse the given ICMP type and code strings, and fill in the
* *type and *code with the results. If there is an error during
* parsing, fill in *error and return STATUS_ERR; otherwise return
* STATUS_OK.
*/
static int parse_icmp_type_and_code(int address_family,
const char *type_string,
const char *code_string,
s32 *type, s32 *code, char **error)
{
int i = 0;
const struct icmp_type_info *icmp_types = NULL;
const struct icmp_code_info *code_table = NULL; /* for this type */
if (address_family == AF_INET)
icmp_types = icmpv4_types;
else if (address_family == AF_INET6)
icmp_types = icmpv6_types;
else
assert(!"bad ip_version in config");
/* Parse the type string. */
if (sscanf(type_string, "type_%d", type) == 1) {
/* Legal but non-standard type in tcpdump-inspired notation. */
} else {
/* Look in our table of known types. */
for (i = 0; icmp_types[i].type_string != NULL; ++i) {
if (!strcmp(type_string, icmp_types[i].type_string)) {
*type = icmp_types[i].type_byte;
code_table = icmp_types[i].code_table;
}
}
}
if (!is_valid_u8(*type)) {
asprintf(error, "bad ICMP type %s", type_string);
return STATUS_ERR;
}
/* Parse the code string. */
if (code_string == NULL) {
*code = 0; /* missing code means code = 0 */
} else if (sscanf(code_string, "code_%d", code) == 1) {
/* Legal but non-standard code in tcpdump-inspired notation. */
} else if (code_table != NULL) {
/* Look in our table of known codes. */
for (i = 0; code_table[i].code_string != NULL; ++i) {
if (!strcmp(code_string, code_table[i].code_string))
*code = code_table[i].code_byte;
}
}
if (!is_valid_u8(*code)) {
asprintf(error, "bad ICMP code %s", code_string);
return STATUS_ERR;
}
return STATUS_OK;
}
void output_atoms(struct membuf *out, struct vec *atoms)
{
struct vec_iterator i[1];
struct vec_iterator i2[1];
struct atom **atomp;
struct atom *atom;
struct expr **exprp;
struct expr *expr;
struct membuf *in;
const char *p;
i32 value;
i32 value2;
dump_sym_table(LOG_DEBUG, s->sym_table);
vec_get_iterator(atoms, i);
while((atomp = vec_iterator_next(i)) != NULL)
{
atom = *atomp;
LOG(LOG_DEBUG, ("yadda\n"));
switch(atom->type)
{
case ATOM_TYPE_OP_ARG_NONE:
LOG(LOG_DEBUG, ("output: $%02X\n", atom->u.op.code));
membuf_append_char(out, atom->u.op.code);
break;
case ATOM_TYPE_OP_ARG_U8:
/* op with argument */
value = resolve_expr(atom->u.op.arg);
if(!is_valid_u8(value))
{
LOG(LOG_ERROR, ("value %d out of range for op $%02X @%p\n",
value, atom->u.op.code, (void*)atom));
exit(1);
}
LOG(LOG_DEBUG, ("output: $%02X $%02X\n",
atom->u.op.code, value & 255));
membuf_append_char(out, atom->u.op.code);
membuf_append_char(out, value);
break;
case ATOM_TYPE_OP_ARG_I8:
/* op with argument */
value = resolve_expr(atom->u.op.arg);
if(!is_valid_i8(value))
{
LOG(LOG_ERROR, ("value %d out of range for op $%02X @%p\n",
value, atom->u.op.code, (void*)atom));
exit(1);
}
LOG(LOG_DEBUG, ("output: $%02X $%02X\n",
atom->u.op.code, value & 255));
membuf_append_char(out, atom->u.op.code);
membuf_append_char(out, value);
break;
case ATOM_TYPE_OP_ARG_UI8:
/* op with argument */
value = resolve_expr(atom->u.op.arg);
if(!is_valid_ui8(value))
{
LOG(LOG_ERROR, ("value %d out of range for op $%02X @%p\n",
value, atom->u.op.code, (void*)atom));
exit(1);
}
LOG(LOG_DEBUG, ("output: $%02X $%02X\n",
atom->u.op.code, value & 255));
membuf_append_char(out, atom->u.op.code);
membuf_append_char(out, value);
break;
case ATOM_TYPE_OP_ARG_U16:
/* op with argument */
value = resolve_expr(atom->u.op.arg);
if(!is_valid_u16(value))
{
LOG(LOG_ERROR, ("value %d out of range for op $%02X @%p\n",
value, atom->u.op.code, (void*)atom));
exit(1);
}
value2 = value / 256;
value = value % 256;
LOG(LOG_DEBUG, ("output: $%02X $%02X $%02X\n",
atom->u.op.code,
value, value2));
membuf_append_char(out, atom->u.op.code);
membuf_append_char(out, value);
membuf_append_char(out, value2);
break;
case ATOM_TYPE_RES:
/* reserve memory statement */
value = resolve_expr(atom->u.res.length);
if(!is_valid_u16(value))
{
LOG(LOG_ERROR, ("length %d for .res(length, value) "
"is out of range\n", value));
exit(1);
}
value2 = resolve_expr(atom->u.res.value);
if(!is_valid_ui8(value2))
{
LOG(LOG_ERROR, ("value %d for .res(length, value) "
"is out of range\n", value));
exit(1);
}
LOG(LOG_DEBUG, ("output: .RES %d, %d\n", value, value2));
while(--value >= 0)
{
membuf_append_char(out, value2);
}
break;
case ATOM_TYPE_BUFFER:
/* include binary file statement */
value = atom->u.buffer.skip;
if(!is_valid_u16(value))
{
LOG(LOG_ERROR, ("value %d for .res(length, value) "
"is out of range\n", value));
exit(1);
}
value2 = atom->u.buffer.length;
if(!is_valid_u16(value2))
{
LOG(LOG_ERROR, ("length %d for .incbin(name, skip, length) "
"is out of range\n", value2));
exit(1);
}
LOG(LOG_DEBUG, ("output: .INCBIN \"%s\", %d, %d\n",
atom->u.buffer.name, value, value2));
in = get_named_buffer(s->named_buffer, atom->u.buffer.name);
p = membuf_get(in);
p += value;
while(--value2 >= 0)
{
membuf_append_char(out, *p++);
}
break;
case ATOM_TYPE_WORD_EXPRS:
vec_get_iterator(atom->u.exprs, i2);
while((exprp = vec_iterator_next(i2)) != NULL)
{
expr = *exprp;
value = resolve_expr(expr);
if(!is_valid_ui16(value))
{
LOG(LOG_ERROR, ("value %d for .word(value, ...) "
"is out of range\n", value));
}
value2 = value / 256;
value = value % 256;
membuf_append_char(out, value);
membuf_append_char(out, value2);
}
LOG(LOG_DEBUG, ("output: %d words\n", vec_count(atom->u.exprs)));
break;
case ATOM_TYPE_BYTE_EXPRS:
vec_get_iterator(atom->u.exprs, i2);
while((exprp = vec_iterator_next(i2)) != NULL)
{
expr = *exprp;
value = resolve_expr(expr);
if(!is_valid_ui8(value))
{
LOG(LOG_ERROR, ("value %d for .byte(value, ...) "
"is out of range\n", value));
}
membuf_append_char(out, value);
}
LOG(LOG_DEBUG, ("output: %d bytes\n", vec_count(atom->u.exprs)));
break;
default:
LOG(LOG_ERROR, ("invalid atom_type %d @%p\n",
atom->type, (void*)atom));
exit(1);
}
}
}
struct packet *new_icmp_packet(int address_family,
enum direction_t direction,
const char *type_string,
const char *code_string,
int protocol,
u32 tcp_start_sequence,
u32 payload_bytes,
s64 mtu,
char **error)
{
s32 type = -1; /* bad type; means "unknown so far" */
s32 code = -1; /* bad code; means "unknown so far" */
struct packet *packet = NULL; /* the newly-allocated result packet */
/* Calculate lengths in bytes of all sections of the packet.
* For now we only support the most common ICMP message
* format, which includes at the end the original outgoing IP
* header and the first 8 bytes after that (which will
* typically have the port info needed to demux the message).
*/
const int ip_fixed_bytes = ip_header_len(address_family);
const int ip_option_bytes = 0;
const int ip_header_bytes = ip_fixed_bytes + ip_option_bytes;
const int echoed_bytes = ip_fixed_bytes + ICMP_ECHO_BYTES;
const int icmp_bytes = icmp_header_len(address_family) + echoed_bytes;
const int ip_bytes = ip_header_bytes + icmp_bytes;
/* Sanity-check all the various lengths */
if (ip_option_bytes & 0x3) {
asprintf(error, "IP options are not padded correctly "
"to ensure IP header is a multiple of 4 bytes: "
"%d excess bytes", ip_option_bytes & 0x3);
goto error_out;
}
assert((ip_header_bytes & 0x3) == 0);
/* Parse the ICMP type and code */
if (parse_icmp_type_and_code(address_family, type_string, code_string,
&type, &code, error))
goto error_out;
assert(is_valid_u8(type));
assert(is_valid_u8(code));
/* Allocate and zero out a packet object of the desired size */
packet = packet_new(ip_bytes);
memset(packet->buffer, 0, ip_bytes);
packet->ip_bytes = ip_bytes;
packet->direction = direction;
packet->flags = 0;
packet->ecn = 0;
/* Set IP header fields */
const enum ip_ecn_t ecn = ECN_NONE;
set_packet_ip_header(packet, address_family, ip_bytes, direction, ecn,
icmp_protocol(address_family));
/* Find the start of the ICMP header and then populate common fields. */
void *icmp_header = packet_start(packet) + ip_header_bytes;
if (set_packet_icmp_header(packet, icmp_header, address_family,
type, code, mtu, error))
goto error_out;
/* All ICMP message types currently supported by this tool
* include a copy of the outbound IP header and the first few
* bytes inside. To ensure that the inbound ICMP message gets
* demuxed to the correct socket in the kernel, here we
* construct enough of a basic IP header and during test
* execution we fill in the port numbers and (if specified)
* TCP sequence number in the TCP header.
*/
u8 *echoed_ip = packet_echoed_ip_header(packet);
const int echoed_ip_bytes = (ip_fixed_bytes +
layer4_header_len(protocol) +
payload_bytes);
set_ip_header(echoed_ip, address_family, echoed_ip_bytes,
reverse_direction(direction), ecn, protocol);
if (protocol == IPPROTO_TCP) {
u32 *seq = packet_echoed_tcp_seq(packet);
*seq = htonl(tcp_start_sequence);
}
return packet;
error_out:
if (packet != NULL)
packet_free(packet);
return NULL;
}
