/***************************************************************************
* payload.cc -- Retrieval of UDP payloads. *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
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***************************************************************************/
/* $Id$ */
#include "nmap.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <map>
#include "NmapOps.h"
#include "nbase.h"
#include "payload.h"
#include "utils.h"
extern NmapOps o;
struct payload {
std::string data;
/* Extra data such as source port goes here. */
};
/* The key for the payload lookup map is a (proto, port) pair. */
struct proto_dport {
u8 proto;
u16 dport;
proto_dport(u8 proto, u16 dport) {
this->proto = proto;
this->dport = dport;
}
bool operator<(const proto_dport& other) const {
if (proto == other.proto)
return dport < other.dport;
else
return proto < other.proto;
}
};
static std::map<struct proto_dport, struct payload> payloads;
/* Newlines are significant because keyword directives (like "source") that
follow the payload string are significant to the end of the line. */
enum token_type {
TOKEN_EOF = 0,
TOKEN_NEWLINE,
TOKEN_SYMBOL,
TOKEN_STRING,
};
struct token {
char text[1024];
size_t len;
};
/* Returns a malloc-allocated list of the ports in portlist. portlist must
contain one or more integers 0 <= p < 65536, separated by commas. */
static unsigned short *parse_portlist(const char *portlist, unsigned int *count) {
uint32_t bitmap[65536 / 32];
unsigned short *result;
unsigned short i;
unsigned int p;
memset(bitmap, 0, sizeof(bitmap));
*count = 0;
for (;;) {
long l;
char *tail;
errno = 0;
l = strtol(portlist, &tail, 10);
if (portlist == tail || errno != 0 || l < 0 || l > 65535)
return NULL;
if (!(bitmap[l / 32] & (1 << (l % 32)))) {
bitmap[l / 32] |= (1 << (l % 32));
(*count)++;
}
if (*tail == '\0')
break;
else if (*tail == ',')
portlist = tail + 1;
else
return NULL;
}
result = (unsigned short *) malloc(sizeof(*result) * *count);
if (result == NULL)
return NULL;
i = 0;
for (p = 0; p < 65536 && i < *count; p++) {
if (bitmap[p / 32] & (1 << (p % 32)))
result[i++] = p;
}
return result;
}
static unsigned long line_no;
/* Get the next token from fp. The return value is the token type, or -1 on
error. The token type is also stored in token->type. For TOKEN_SYMBOL and
TOKEN_STRING, the text is stored in token->text and token->len. The text is
null terminated. */
static int next_token(FILE *fp, struct token *token) {
unsigned int i, tmplen;
int c;
token->len = 0;
/* Skip whitespace and comments. */
while (isspace(c = fgetc(fp)) && c != '\n')
;
if (c == EOF) {
return TOKEN_EOF;
} else if (c == '\n') {
line_no++;
return TOKEN_NEWLINE;
} else if (c == '#') {
while ((c = fgetc(fp)) != EOF && c != '\n')
;
if (c == EOF) {
return TOKEN_EOF;
} else {
line_no++;
return TOKEN_NEWLINE;
}
} else if (c == '"') {
i = 0;
while ((c = fgetc(fp)) != EOF && c != '\n' && c != '"') {
if (i + 1 >= sizeof(token->text))
return -1;
if (c == '\\') {
token->text[i++] = '\\';
if (i + 1 >= sizeof(token->text))
return -1;
c = fgetc(fp);
if (c == EOF)
return -1;
}
token->text[i++] = c;
}
if (c != '"')
return -1;
token->text[i] = '\0';
if (cstring_unescape(token->text, &tmplen) == NULL)
return -1;
token->len = tmplen;
return TOKEN_STRING;
} else {
i = 0;
if (i + 1 >= sizeof(token->text))
return -1;
token->text[i++] = c;
while ((c = fgetc(fp)) != EOF && (isalnum(c) || c == ',')) {
if (i + 1 >= sizeof(token->text))
return -1;
token->text[i++] = c;
}
ungetc(c, fp);
token->text[i] = '\0';
token->len = i;
return TOKEN_SYMBOL;
}
return -1;
}
/* Loop over fp, reading tokens and adding payloads to the global payloads map
as they are completed. Returns -1 on error. */
static int load_payloads_from_file(FILE *fp) {
struct token token;
int type;
line_no = 1;
type = next_token(fp, &token);
for (;;) {
unsigned short *ports;
unsigned int count, p;
std::string payload_data;
while (type == TOKEN_NEWLINE)
type = next_token(fp, &token);
if (type == TOKEN_EOF)
break;
if (type != TOKEN_SYMBOL || strcmp(token.text, "udp") != 0) {
fprintf(stderr, "Expected \"udp\" at line %lu of %s.\n", line_no, PAYLOAD_FILENAME);
return -1;
}
type = next_token(fp, &token);
if (type != TOKEN_SYMBOL) {
fprintf(stderr, "Expected a port list at line %lu of %s.\n", line_no, PAYLOAD_FILENAME);
return -1;
}
ports = parse_portlist(token.text, &count);
if (ports == NULL) {
fprintf(stderr, "Can't parse port list \"%s\" at line %lu of %s.\n", token.text, line_no, PAYLOAD_FILENAME);
return -1;
}
payload_data.clear();
for (;;) {
type = next_token(fp, &token);
if (type == TOKEN_STRING)
payload_data.append(token.text, token.len);
else if (type == TOKEN_NEWLINE)
; /* Nothing. */
else
break;
}
/* Ignore keywords like "source" to the end of the line. */
if (type == TOKEN_SYMBOL && strcmp(token.text, "udp") != 0) {
while (type != -1 && type != TOKEN_EOF && type != TOKEN_NEWLINE)
type = next_token(fp, &token);
}
for (p = 0; p < count; p++) {
struct proto_dport key(IPPROTO_UDP, ports[p]);
struct payload payload;
payload.data = payload_data;
payloads[key] = payload;
}
free(ports);
}
return 0;
}
/* Ensure that the payloads map is initialized from the nmap-payloads file. This
function keeps track of whether it has been called and does nothing after it
is called the first time. */
int init_payloads(void) {
static bool payloads_loaded = false;
char filename[256];
FILE *fp;
int ret;
if (payloads_loaded)
return 0;
payloads_loaded = true;
if (nmap_fetchfile(filename, sizeof(filename), PAYLOAD_FILENAME) != 1) {
error("Cannot find %s. UDP payloads are disabled.", PAYLOAD_FILENAME);
return 0;
}
fp = fopen(filename, "r");
if (fp == NULL) {
fprintf(stderr, "Can't open %s for reading.\n", filename);
return -1;
}
/* Record where this data file was found. */
o.loaded_data_files[PAYLOAD_FILENAME] = filename;
ret = load_payloads_from_file(fp);
fclose(fp);
return ret;
}
/* Get a payload appropriate for the given UDP port. For certain selected ports
a payload is returned, and for others a zero-length payload is returned. The
length is returned through the length pointer. */
const char *udp_port2payload(u16 dport, size_t *length) {
static const char *payload_null = "";
std::map<struct proto_dport, struct payload>::iterator it;
proto_dport pp(IPPROTO_UDP, dport);
it = payloads.find(pp);
if (it != payloads.end()) {
*length = it->second.data.size();
return it->second.data.data();
} else {
*length = 0;
return payload_null;
}
}
/* Get a payload appropriate for the given UDP port. If --data-length was used,
returns the global random payload. Otherwise, for certain selected ports a
payload is returned, and for others a zero-length payload is returned. The
length is returned through the length pointer. */
const char *get_udp_payload(u16 dport, size_t *length) {
if (o.extra_payload != NULL) {
*length = o.extra_payload_length;
return o.extra_payload;
} else {
return udp_port2payload(dport, length);
}
}