From 3e55b9fe622957444c928b41f02e6e965589e247 Mon Sep 17 00:00:00 2001
From: Julien Boeuf <jboeuf@google.com>
Date: Thu, 25 Jun 2015 17:54:19 +0200
Subject: [PATCH] Base64 decode improvements.
- Allow ablity to specify the length for decoding.
- Allow for non-padded encodings to be decoded properly.
---
src/core/security/base64.c | 99 +++++++++++++++++++++-----------
src/core/security/base64.h | 4 ++
test/core/security/base64_test.c | 38 ++++++++++++
3 files changed, 108 insertions(+), 33 deletions(-)
diff --git a/src/core/security/base64.c b/src/core/security/base64.c
index 3f28c09611..d029e33928 100644
--- a/src/core/security/base64.c
+++ b/src/core/security/base64.c
@@ -120,7 +120,68 @@ char *grpc_base64_encode(const void *vdata, size_t data_size, int url_safe,
}
gpr_slice grpc_base64_decode(const char *b64, int url_safe) {
- size_t b64_len = strlen(b64);
+ return grpc_base64_decode_with_len(b64, strlen(b64), url_safe);
+}
+
+static void decode_one_char(const unsigned char *codes, unsigned char *result,
+ size_t *result_offset) {
+ gpr_uint32 packed = (codes[0] << 2) | (codes[1] >> 4);
+ result[(*result_offset)++] = (unsigned char)packed;
+}
+
+static void decode_two_chars(const unsigned char *codes, unsigned char *result,
+ size_t *result_offset) {
+ gpr_uint32 packed = (codes[0] << 10) | (codes[1] << 4) | (codes[2] >> 2);
+ result[(*result_offset)++] = (unsigned char)(packed >> 8);
+ result[(*result_offset)++] = (unsigned char)(packed);
+}
+
+static int decode_group(const unsigned char *codes, size_t num_codes,
+ unsigned char *result, size_t *result_offset) {
+ GPR_ASSERT(num_codes <= 4);
+
+ /* Short end groups that may not have padding. */
+ if (num_codes == 1) {
+ gpr_log(GPR_ERROR, "Invalid group. Must be at least 2 bytes.");
+ return 0;
+ }
+ if (num_codes == 2) {
+ decode_one_char(codes, result, result_offset);
+ return 1;
+ }
+ if (num_codes == 3) {
+ decode_two_chars(codes, result, result_offset);
+ return 1;
+ }
+
+ /* Regular 4 byte groups with padding or not. */
+ GPR_ASSERT(num_codes == 4);
+ if (codes[0] == GRPC_BASE64_PAD_BYTE || codes[1] == GRPC_BASE64_PAD_BYTE) {
+ gpr_log(GPR_ERROR, "Invalid padding detected.");
+ return 0;
+ }
+ if (codes[2] == GRPC_BASE64_PAD_BYTE) {
+ if (codes[3] == GRPC_BASE64_PAD_BYTE) {
+ decode_one_char(codes, result, result_offset);
+ } else {
+ gpr_log(GPR_ERROR, "Invalid padding detected.");
+ return 0;
+ }
+ } else if (codes[3] == GRPC_BASE64_PAD_BYTE) {
+ decode_two_chars(codes, result, result_offset);
+ } else {
+ /* No padding. */
+ gpr_uint32 packed =
+ (codes[0] << 18) | (codes[1] << 12) | (codes[2] << 6) | codes[3];
+ result[(*result_offset)++] = (unsigned char)(packed >> 16);
+ result[(*result_offset)++] = (unsigned char)(packed >> 8);
+ result[(*result_offset)++] = (unsigned char)(packed);
+ }
+ return 1;
+}
+
+gpr_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
+ int url_safe) {
gpr_slice result = gpr_slice_malloc(b64_len);
unsigned char *current = GPR_SLICE_START_PTR(result);
size_t result_size = 0;
@@ -151,43 +212,15 @@ gpr_slice grpc_base64_decode(const char *b64, int url_safe) {
} else {
codes[num_codes++] = (unsigned char)code;
if (num_codes == 4) {
- if (codes[0] == GRPC_BASE64_PAD_BYTE ||
- codes[1] == GRPC_BASE64_PAD_BYTE) {
- gpr_log(GPR_ERROR, "Invalid padding detected.");
- goto fail;
- }
- if (codes[2] == GRPC_BASE64_PAD_BYTE) {
- if (codes[3] == GRPC_BASE64_PAD_BYTE) {
- /* Double padding. */
- gpr_uint32 packed = (gpr_uint32)((codes[0] << 2) | (codes[1] >> 4));
- current[result_size++] = (unsigned char)packed;
- } else {
- gpr_log(GPR_ERROR, "Invalid padding detected.");
- goto fail;
- }
- } else if (codes[3] == GRPC_BASE64_PAD_BYTE) {
- /* Single padding. */
- gpr_uint32 packed =
- (gpr_uint32)((codes[0] << 10) | (codes[1] << 4) | (codes[2] >> 2));
- current[result_size++] = (unsigned char)(packed >> 8);
- current[result_size++] = (unsigned char)(packed);
- } else {
- /* No padding. */
- gpr_uint32 packed =
- (gpr_uint32)((codes[0] << 18) | (codes[1] << 12) | (codes[2] << 6) | codes[3]);
- current[result_size++] = (unsigned char)(packed >> 16);
- current[result_size++] = (unsigned char)(packed >> 8);
- current[result_size++] = (unsigned char)(packed);
- }
+ if (!decode_group(codes, num_codes, current, &result_size)) goto fail;
num_codes = 0;
}
}
}
- if (num_codes != 0) {
- gpr_log(GPR_ERROR, "Invalid base64.");
- gpr_slice_unref(result);
- return gpr_empty_slice();
+ if (num_codes != 0 &&
+ !decode_group(codes, num_codes, current, &result_size)) {
+ goto fail;
}
GPR_SLICE_SET_LENGTH(result, result_size);
return result;
diff --git a/src/core/security/base64.h b/src/core/security/base64.h
index 6a7cd8e96c..b9abc07b52 100644
--- a/src/core/security/base64.h
+++ b/src/core/security/base64.h
@@ -45,4 +45,8 @@ char *grpc_base64_encode(const void *data, size_t data_size, int url_safe,
slice in case of failure. */
gpr_slice grpc_base64_decode(const char *b64, int url_safe);
+/* Same as above except that the length is provided by the caller. */
+gpr_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
+ int url_safe);
+
#endif /* GRPC_INTERNAL_CORE_SECURITY_BASE64_H */
diff --git a/test/core/security/base64_test.c b/test/core/security/base64_test.c
index a922896bc3..f8b7ebf554 100644
--- a/test/core/security/base64_test.c
+++ b/test/core/security/base64_test.c
@@ -169,6 +169,43 @@ static void test_rfc4648_test_vectors(void) {
gpr_free(b64);
}
+static void test_unpadded_decode(void) {
+ gpr_slice decoded;
+
+ decoded = grpc_base64_decode("Zm9vYmFy", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "foobar") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("Zm9vYmE", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "fooba") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("Zm9vYg", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "foob") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("Zm9v", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "foo") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("Zm8", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "fo") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("Zg", 0);
+ GPR_ASSERT(!GPR_SLICE_IS_EMPTY(decoded));
+ GPR_ASSERT(gpr_slice_str_cmp(decoded, "f") == 0);
+ gpr_slice_unref(decoded);
+
+ decoded = grpc_base64_decode("", 0);
+ GPR_ASSERT(GPR_SLICE_IS_EMPTY(decoded));
+}
+
int main(int argc, char **argv) {
grpc_test_init(argc, argv);
test_simple_encode_decode_b64_no_multiline();
@@ -181,5 +218,6 @@ int main(int argc, char **argv) {
test_full_range_encode_decode_b64_urlsafe_multiline();
test_url_safe_unsafe_mismtach_failure();
test_rfc4648_test_vectors();
+ test_unpadded_decode();
return 0;
}
--
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