This patch adds into libbb decode_base64() function to decode base64 string. Needs for DHCPv6 authorization keys decode.
decode_base64() - decode base64 string
Signed-off-by: Leonid Lisovskiy <[email protected]> --- include/libbb.h | 1 libbb/uuencode.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 76 insertions(+) diff --git a/include/libbb.h b/include/libbb.h index f79b693..37d48df 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -1599,6 +1599,7 @@ enum { BASE64_FLAG_NO_STOP_CHAR = 0x80, }; void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags); +int FAST_FUNC decode_base64(const char *src, char *dst, int dstlen); typedef struct md5_ctx_t { uint8_t wbuffer[64]; /* always correctly aligned for uint64_t */ diff --git a/libbb/uuencode.c b/libbb/uuencode.c index 03e708f..b7e59fc 100644 --- a/libbb/uuencode.c +++ b/libbb/uuencode.c @@ -143,3 +143,78 @@ void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags) fputc(translated[2] << 6 | translated[3], dst_stream); } /* while (1) */ } + +/* + * Decode base64 encoded string. + */ +int FAST_FUNC decode_base64(const char *src, char *buf, int buflen) +{ + int len = 0; + int term_count = 0; + + while (1) { + unsigned char translated[4]; + int count = 0; + + /* Process one group of 4 chars */ + while (count < 4) { + char *table_ptr; + int ch; + + /* Get next _valid_ character. + * bb_uuenc_tbl_base64[] contains this string: + * 0 1 2 3 4 5 6 + * 012345678901234567890123456789012345678901234567890123456789012345 + * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n" + */ + do { + ch = *(src++); + if (ch == '\0') { + if (count == 0) + return len; + else + /* truncated base64 input */ + return -1; + } + table_ptr = strchr(bb_uuenc_tbl_base64, ch); +//Note that then we may need to still allow '\r' (for mail processing) + } while (!table_ptr); + + /* Convert encoded character to decimal */ + ch = table_ptr - bb_uuenc_tbl_base64; + + if (ch == 65 /* '\n' */) { + /* Terminating "====" line? */ + if (term_count == 4) + return len; /* yes */ + term_count = 0; + continue; + } + /* ch is 64 if char was '=', otherwise 0..63 */ + translated[count] = ch & 63; /* 64 -> 0 */ + if (ch == 64) { + term_count++; + break; + } + count++; + term_count = 0; + } + + /* Merge 6 bit chars to 8 bit. + * count can be < 4 when we decode the tail: + * "eQ==" -> "y", not "y NUL NUL" + */ + len += (count - 1); + if (len > buflen) + /* output buffer too small */ + return -2; + if (count > 1) + *(buf++) = translated[0] << 2 | translated[1] >> 4; + if (count > 2) + *(buf++) = translated[1] << 4 | translated[2] >> 2; + if (count > 3) + *(buf++) = translated[2] << 6 | translated[3]; + } /* while (1) */ + + return len; +}
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