util/mime: skip over any invalid char

For certain edge case handling for spaces, spaces were handled
particularly in the remainder processing functions. Make sure that now
that as per RFC 2045, util-base64 would skip over any invalid char, the
edge cases in MIME processor also be handled the same way.

This completes the work done in e46b033.

Ticket 6135
Ticket 6207

(cherry picked from commit 789353bc1e1aa23d075f16af25df84df00c68682)

diff --git a/src/util-base64.c b/src/util-base64.c
index f2abfe4a2e26d91d49e3cec04db08493639cc1a8..13a8e1eabb23dc0e4b3761aea1c125ef7e9cfe13 100644 (file)
--- a/src/util-base64.c
+++ b/src/util-base64.c
@@ -62,6 +62,21 @@ static inline int GetBase64Value(uint8_t c)
     return val;
 }
 
+/**
+ * \brief Checks if the given char in a byte array is Base64 alphabet
+ *
+ * \param Char that needs to be checked
+ *
+ * \return True if the char was Base64 alphabet, False otherwise
+ */
+bool IsBase64Alphabet(uint8_t encoded_byte)
+{
+    if (GetBase64Value(encoded_byte) < 0 && encoded_byte != '=') {
+        return false;
+    }
+    return true;
+}
+
 /**
  * \brief Decodes a 4-byte base64-encoded block into a 3-byte ascii-encoded block
  *

diff --git a/src/util-base64.h b/src/util-base64.h
index fdaf9d6fa0127e32c3dc9ed1f9e553d6d2bf8d03..ce490d46584ad129773ca2d923ac9bb64e5c62c5 100644 (file)
--- a/src/util-base64.h
+++ b/src/util-base64.h
@@ -95,6 +95,7 @@ typedef enum {
 /* Function prototypes */
 Base64Ecode DecodeBase64(uint8_t *dest, uint32_t dest_size, const uint8_t *src, uint32_t len,
         uint32_t *consumed_bytes, uint32_t *decoded_bytes, Base64Mode mode);
+bool IsBase64Alphabet(uint8_t encoded_byte);
 
 #endif
 

diff --git a/src/util-decode-mime.c b/src/util-decode-mime.c
index d5e2f1c2e5a916d446d5938d99863d5b48cab682..b6c231b363748316146bab58b2f7ae6e68e67977 100644 (file)
--- a/src/util-decode-mime.c
+++ b/src/util-decode-mime.c
@@ -1197,7 +1197,7 @@ static uint32_t ProcessBase64Remainder(
 
     /* Strip spaces in remainder */
     for (uint8_t i = 0; i < state->bvr_len; i++) {
-        if (state->bvremain[i] != ' ') {
+        if (IsBase64Alphabet(state->bvremain[i])) {
             block[cnt++] = state->bvremain[i];
         }
     }
@@ -1205,7 +1205,7 @@ static uint32_t ProcessBase64Remainder(
     /* if we don't have 4 bytes see if we can fill it from `buf` */
     if (buf && len > 0 && cnt != B64_BLOCK) {
         for (uint32_t i = 0; i < len && cnt < B64_BLOCK; i++) {
-            if (buf[i] != ' ') {
+            if (IsBase64Alphabet(buf[i])) {
                 block[cnt++] = buf[i];
             }
             buf_consumed++;
@@ -1289,7 +1289,8 @@ static inline MimeDecRetCode ProcessBase64BodyLineCopyRemainder(
         return MIME_DEC_ERR_DATA;
 
     for (uint32_t i = offset; i < buf_len; i++) {
-        if (buf[i] != ' ') {
+        // Skip any characters outside of the base64 alphabet as per RFC 2045
+        if (IsBase64Alphabet(buf[i])) {
             DEBUG_VALIDATE_BUG_ON(state->bvr_len >= B64_BLOCK);
             if (state->bvr_len >= B64_BLOCK)
                 return MIME_DEC_ERR_DATA;