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Adds support to EscapeSeqDecode transformation

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This commit is contained in:
Felipe Zimmerle 2015-10-23 14:22:03 -03:00
parent 1716add77b
commit 4168ebc2b3
3 changed files with 120 additions and 12 deletions
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129
src/actions/transformations/escape_seq_decode.cc
View File

@ -24,7 +24,7 @@
#include "modsecurity/assay.h"
#include "actions/transformations/transformation.h"
#include "src/utils.h"
namespace ModSecurity {
namespace actions {
@ -35,18 +35,125 @@ EscapeSeqDecode::EscapeSeqDecode(std::string action)
this->action_kind = 1;
}
int EscapeSeqDecode::ansi_c_sequences_decode_inplace(unsigned char *input,
int input_len) {
unsigned char *d = input;
int i, count;
i = count = 0;
while (i < input_len) {
if ((input[i] == '\\') && (i + 1 < input_len)) {
int c = -1;
switch(input[i + 1]) {
case 'a' :
c = '\a';
break;
case 'b' :
c = '\b';
break;
case 'f' :
c = '\f';
break;
case 'n' :
c = '\n';
break;
case 'r' :
c = '\r';
break;
case 't' :
c = '\t';
break;
case 'v' :
c = '\v';
break;
case '\\' :
c = '\\';
break;
case '?' :
c = '?';
break;
case '\'' :
c = '\'';
break;
case '"' :
c = '"';
break;
}
if (c != -1) i += 2;
/* Hexadecimal or octal? */
if (c == -1) {
if ((input[i + 1] == 'x')||(input[i + 1] == 'X')) {
/* Hexadecimal. */
if ((i + 3 < input_len)&&(isxdigit(input[i + 2]))&&(isxdigit(input[i + 3]))) {
/* Two digits. */
c = x2c(&input[i + 2]);
i += 4;
} else {
/* Invalid encoding, do nothing. */
}
}
else
if (ISODIGIT(input[i + 1])) { /* Octal. */
char buf[4];
int j = 0;
while((i + 1 + j < input_len)&&(j < 3)) {
buf[j] = input[i + 1 + j];
j++;
if (!ISODIGIT(input[i + 1 + j])) break;
}
buf[j] = '\0';
if (j > 0) {
c = strtol(buf, NULL, 8);
i += 1 + j;
}
}
}
if (c == -1) {
/* Didn't recognise encoding, copy raw bytes. */
*d++ = input[i + 1];
count++;
i += 2;
} else {
/* Converted the encoding. */
*d++ = c;
count++;
}
} else {
/* Input character not a backslash, copy it. */
*d++ = input[i++];
count++;
}
}
*d = '\0';
return count;
}
std::string EscapeSeqDecode::evaluate(std::string value,
Assay *assay) {
/**
* @todo Implement the transformation EscapeSeqDecode
*/
if (assay) {
#ifndef NO_LOGS
assay->debug(4, "Transformation EscapeSeqDecode is " \
"not implemented yet.");
#endif
}
return value;
unsigned char *tmp = (unsigned char *) malloc(sizeof(char)
* value.size() + 1);
memcpy(tmp, value.c_str(), value.size() + 1);
tmp[value.size()] = '\0';
int size = ansi_c_sequences_decode_inplace(tmp, value.size());
std::string ret("");
ret.assign((char *)tmp, size);
//ret.append((const char *)tmp);
free(tmp);
return ret;
}
} // namespace transformations

1
src/actions/transformations/escape_seq_decode.h
View File

@ -33,6 +33,7 @@ class EscapeSeqDecode : public Transformation {
explicit EscapeSeqDecode(std::string action);
std::string evaluate(std::string exp,
Assay *assay) override;
int ansi_c_sequences_decode_inplace(unsigned char *input, int input_len);
};
} // namespace transformations

2
src/actions/transformations/transformation.cc
View File

@ -79,7 +79,7 @@ Transformation* Transformation::instantiate(std::string a) {
IF_MATCH(cmd_line) { return new CmdLine(a); }
IF_MATCH(compress_whitespace) { return new CompressWhitespace(a); }
IF_MATCH(cssDecode) { return new CssDecode(a); }
IF_MATCH(escape_seq_decode) { return new EscapeSeqDecode(a); }
IF_MATCH(escapeSeqDecode) { return new EscapeSeqDecode(a); }
IF_MATCH(hexDecode) { return new HexDecode(a); }
IF_MATCH(hexEncode) { return new HexEncode(a); }
IF_MATCH(htmlEntityDecode) { return new HtmlEntityDecode(a); }