/* vi: set sw=4 ts=4: */ /* * Copyright 2003, Glenn McGrath * Copyright 2006, Rob Landley <rob@landley.net> * Copyright 2010, Denys Vlasenko * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ #include "libbb.h" /* Conversion table. for base 64 */ const char bb_uuenc_tbl_base64[65 + 1] ALIGN1 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '=' /* termination character */, '\0' /* needed for uudecode.c only */ }; const char bb_uuenc_tbl_std[65] ALIGN1 = { '`', '!', '"', '#', '$', '%', '&', '\'', '(', ')', '*', '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', '\\', ']', '^', '_', '`' /* termination character */ }; /* * Encode bytes at S of length LENGTH to uuencode or base64 format and place it * to STORE. STORE will be 0-terminated, and must point to a writable * buffer of at least 1+BASE64_LENGTH(length) bytes. * where BASE64_LENGTH(len) = (4 * ((LENGTH + 2) / 3)) */ void FAST_FUNC bb_uuencode(char *p, const void *src, int length, const char *tbl) { const unsigned char *s = src; /* Transform the 3x8 bits to 4x6 bits */ while (length > 0) { unsigned s1, s2; /* Are s[1], s[2] valid or should be assumed 0? */ s1 = s2 = 0; length -= 3; /* can be >=0, -1, -2 */ if (length >= -1) { s1 = s[1]; if (length >= 0) s2 = s[2]; } *p++ = tbl[s[0] >> 2]; *p++ = tbl[((s[0] & 3) << 4) + (s1 >> 4)]; *p++ = tbl[((s1 & 0xf) << 2) + (s2 >> 6)]; *p++ = tbl[s2 & 0x3f]; s += 3; } /* Zero-terminate */ *p = '\0'; /* If length is -2 or -1, pad last char or two */ while (length) { *--p = tbl[64]; length++; } } /* * Decode base64 encoded string. Stops on '\0'. * * Returns: pointer to the undecoded part of source. * If points to '\0', then the source was fully decoded. * (*pp_dst): advanced past the last written byte. */ const char* FAST_FUNC decode_base64(char **pp_dst, const char *src) { char *dst = *pp_dst; const char *src_tail; while (1) { unsigned char six_bit[4]; int count = 0; /* Fetch up to four 6-bit values */ src_tail = src; 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 * 01234567890123456789012345678901234567890123456789012345678901234 * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" */ do { ch = *src; if (ch == '\0') { if (count == 0) { /* Example: * If we decode "QUJD <NUL>", we want * to return ptr to NUL, not to ' ', * because we did fully decode * the string (to "ABC"). */ src_tail = src; } goto ret; } src++; table_ptr = strchr(bb_uuenc_tbl_base64, ch); //TODO: add BASE64_FLAG_foo to die on bad char? } while (!table_ptr); /* Convert encoded character to decimal */ ch = table_ptr - bb_uuenc_tbl_base64; /* ch is 64 if char was '=', otherwise 0..63 */ if (ch == 64) break; six_bit[count] = ch; count++; } /* Transform 6-bit values to 8-bit ones. * count can be < 4 when we decode the tail: * "eQ==" -> "y", not "y NUL NUL". * Note that (count > 1) is always true, * "x===" encoding is not valid: * even a single zero byte encodes as "AA==". * However, with current logic we come here with count == 1 * when we decode "==" tail. */ if (count > 1) *dst++ = six_bit[0] << 2 | six_bit[1] >> 4; if (count > 2) *dst++ = six_bit[1] << 4 | six_bit[2] >> 2; if (count > 3) *dst++ = six_bit[2] << 6 | six_bit[3]; /* Note that if we decode "AA==" and ate first '=', * we just decoded one char (count == 2) and now we'll * do the loop once more to decode second '='. */ } /* while (1) */ ret: *pp_dst = dst; return src_tail; } /* * Decode base64 encoded stream. * Can stop on EOF, specified char, or on uuencode-style "====" line: * flags argument controls it. */ void FAST_FUNC read_base64(FILE *src_stream, FILE *dst_stream, int flags) { /* Note that EOF _can_ be passed as exit_char too */ #define exit_char ((int)(signed char)flags) #define uu_style_end (flags & BASE64_FLAG_UU_STOP) /* uuencoded files have 61 byte lines. Use 64 byte buffer * to process line at a time. */ enum { BUFFER_SIZE = 64 }; char in_buf[BUFFER_SIZE + 2]; char out_buf[BUFFER_SIZE / 4 * 3 + 2]; char *out_tail; const char *in_tail; int term_seen = 0; int in_count = 0; while (1) { while (in_count < BUFFER_SIZE) { int ch = fgetc(src_stream); if (ch == exit_char) { if (in_count == 0) return; term_seen = 1; break; } if (ch == EOF) { term_seen = 1; break; } /* Prevent "====" line to be split: stop if we see '\n'. * We can also skip other whitespace and skirt the problem * of files with NULs by stopping on any control char or space: */ if (ch <= ' ') break; in_buf[in_count++] = ch; } in_buf[in_count] = '\0'; /* Did we encounter "====" line? */ if (uu_style_end && strcmp(in_buf, "====") == 0) return; out_tail = out_buf; in_tail = decode_base64(&out_tail, in_buf); fwrite(out_buf, (out_tail - out_buf), 1, dst_stream); if (term_seen) { /* Did we consume ALL characters? */ if (*in_tail == '\0') return; /* No */ bb_error_msg_and_die("truncated base64 input"); } /* It was partial decode */ in_count = strlen(in_tail); memmove(in_buf, in_tail, in_count); } }