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base64: add Base64Mode enum

Browse Source
pull/7487/head
Shivani Bhardwaj 3 years ago committed by Victor Julien
parent 1e3282f363
commit 9131d1d857
6 changed files with 58 additions and 18 deletions
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12
src/datasets.c
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@ -323,7 +323,8 @@ static int DatasetLoadString(Dataset *set)
// coverity[alloc_strlen : FALSE]
uint8_t decoded[strlen(line)];
uint32_t len = DecodeBase64(decoded, (const uint8_t *)line, strlen(line), 1);
uint32_t len =
DecodeBase64(decoded, (const uint8_t *)line, strlen(line), BASE64_MODE_STRICT);
if (len == 0)
FatalError(SC_ERR_FATAL, "bad base64 encoding %s/%s",
set->name, set->load);
@ -340,7 +341,8 @@ static int DatasetLoadString(Dataset *set)
// coverity[alloc_strlen : FALSE]
uint8_t decoded[strlen(line)];
uint32_t len = DecodeBase64(decoded, (const uint8_t *)line, strlen(line), 1);
uint32_t len =
DecodeBase64(decoded, (const uint8_t *)line, strlen(line), BASE64_MODE_STRICT);
if (len == 0)
FatalError(SC_ERR_FATAL, "bad base64 encoding %s/%s",
set->name, set->load);
@ -1142,7 +1144,8 @@ int DatasetAddSerialized(Dataset *set, const char *string)
case DATASET_TYPE_STRING: {
// coverity[alloc_strlen : FALSE]
uint8_t decoded[strlen(string)];
uint32_t len = DecodeBase64(decoded, (const uint8_t *)string, strlen(string), 1);
uint32_t len = DecodeBase64(
decoded, (const uint8_t *)string, strlen(string), BASE64_MODE_STRICT);
if (len == 0) {
return -2;
}
@ -1224,7 +1227,8 @@ int DatasetRemoveSerialized(Dataset *set, const char *string)
case DATASET_TYPE_STRING: {
// coverity[alloc_strlen : FALSE]
uint8_t decoded[strlen(string)];
uint32_t len = DecodeBase64(decoded, (const uint8_t *)string, strlen(string), 1);
uint32_t len = DecodeBase64(
decoded, (const uint8_t *)string, strlen(string), BASE64_MODE_STRICT);
if (len == 0) {
return -2;
}

4
src/detect-base64-decode.c
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@ -87,8 +87,8 @@ int DetectBase64DecodeDoMatch(DetectEngineThreadCtx *det_ctx, const Signature *s
PrintRawDataFp(stdout, payload, decode_len);
#endif
det_ctx->base64_decoded_len = DecodeBase64(det_ctx->base64_decoded,
payload, decode_len, 0);
det_ctx->base64_decoded_len =
DecodeBase64(det_ctx->base64_decoded, payload, decode_len, BASE64_MODE_RELAX);
SCLogDebug("Decoded %d bytes from base64 data.",
det_ctx->base64_decoded_len);
#if 0

1
src/runmode-unittests.c
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@ -172,6 +172,7 @@ static void RegisterUnittests(void)
ThreadMacrosRegisterTests();
UtilSpmSearchRegistertests();
UtilActionRegisterTests();
Base64RegisterTests();
SCClassConfRegisterTests();
SCThresholdConfRegisterTests();
SCRConfRegisterTests();

36
src/util-base64.c
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@ -23,7 +23,7 @@
*/
#include "util-base64.h"
#include "util-unittest.h"
/* Constants */
#define BASE64_TABLE_MAX 122
@ -88,8 +88,7 @@ static inline void DecodeBase64Block(uint8_t ascii[ASCII_BLOCK], uint8_t b64[B64
*
* \return Number of bytes decoded, or 0 if no data is decoded or it fails
*/
uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len,
int strict)
uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len, Base64Mode mode)
{
int val;
uint32_t padding = 0, numDecoded = 0, bbidx = 0, valid = 1, i;
@ -102,11 +101,13 @@ uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len,
/* Get decimal representation */
val = GetBase64Value(src[i]);
if (val < 0) {
if (mode == BASE64_MODE_RFC2045 && src[i] == ' ') {
continue;
}
/* Invalid character found, so decoding fails */
if (src[i] != '=') {
valid = 0;
if (strict) {
if (mode != BASE64_MODE_RELAX) {
numDecoded = 0;
}
break;
@ -149,3 +150,28 @@ uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len,
return numDecoded;
}
#ifdef UNITTESTS
static int DecodeString(void)
{
/*
* SGV sbG8= : Hello
* SGVsbG8gV29ybGQ= : Hello World
* */
const char *src = "SGVs bG8 gV29y bGQ=";
uint8_t *dst = SCMalloc(sizeof(src) * 30);
int res = DecodeBase64(dst, (const uint8_t *)src, 30, 1);
printf("%d\n", res);
printf("dst str = \"%s\"", (const char *)dst);
FAIL_IF(res <= 0);
SCFree(dst);
PASS;
}
void Base64RegisterTests(void)
{
UtRegisterTest("DecodeString", DecodeString);
}
#endif

13
src/util-base64.h
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@ -48,8 +48,17 @@
#define ASCII_BLOCK 3
#define B64_BLOCK 4
typedef enum {
BASE64_MODE_RELAX,
BASE64_MODE_RFC2045, /* SPs are allowed during transfer but must be skipped by Decoder */
BASE64_MODE_STRICT,
} Base64Mode;
/* Function prototypes */
uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len,
int strict);
uint32_t DecodeBase64(uint8_t *dest, const uint8_t *src, uint32_t len, Base64Mode mode);
#endif
#ifdef UNITTESTS
void Base64RegisterTests(void);
#endif

10
src/util-decode-mime.c
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@ -1250,8 +1250,8 @@ static uint8_t ProcessBase64Remainder(
/* Only decode if divisible by 4 */
if (state->bvr_len == B64_BLOCK || force) {
remdec = DecodeBase64(state->data_chunk + state->data_chunk_len,
state->bvremain, state->bvr_len, 1);
remdec = DecodeBase64(state->data_chunk + state->data_chunk_len, state->bvremain,
state->bvr_len, BASE64_MODE_RFC2045);
if (remdec > 0) {
/* Track decoded length */
@ -1352,8 +1352,8 @@ static int ProcessBase64BodyLine(const uint8_t *buf, uint32_t len,
SCLogDebug("Decoding: %u", len - rem1 - rem2);
numDecoded = DecodeBase64(state->data_chunk + state->data_chunk_len,
buf + offset, tobuf, 1);
numDecoded = DecodeBase64(state->data_chunk + state->data_chunk_len, buf + offset,
tobuf, BASE64_MODE_RFC2045);
if (numDecoded > 0) {
/* Track decoded length */
@ -3190,7 +3190,7 @@ static int MimeBase64DecodeTest01(void)
if (dst == NULL)
return 0;
ret = DecodeBase64(dst, (const uint8_t *)base64msg, strlen(base64msg), 1);
ret = DecodeBase64(dst, (const uint8_t *)base64msg, strlen(base64msg), BASE64_MODE_RFC2045);
if (memcmp(dst, msg, strlen(msg)) == 0) {
ret = 1;

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