mirror of
https://github.com/zeek/zeek.git
synced 2025-10-02 06:38:20 +00:00
258 lines
7 KiB
C++
258 lines
7 KiB
C++
#include "zeek/Base64.h"
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#include "zeek/zeek-config.h"
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#include <cmath>
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#include "zeek/Conn.h"
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#include "zeek/Reporter.h"
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#include "zeek/ZeekString.h"
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namespace zeek::detail {
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int Base64Converter::default_base64_table[256];
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const std::string Base64Converter::default_alphabet =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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void Base64Converter::Encode(int len, const unsigned char* data, int* pblen, char** pbuf) {
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int blen;
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char* buf;
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if ( ! pbuf )
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reporter->InternalError("nil pointer to encoding result buffer");
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if ( *pbuf && (*pblen % 4 != 0) )
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reporter->InternalError("Base64 encode buffer not a multiple of 4");
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if ( *pbuf ) {
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buf = *pbuf;
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blen = *pblen;
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}
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else {
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blen = (int)(4 * ceil((double)len / 3));
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*pbuf = buf = new char[blen];
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*pblen = blen;
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}
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for ( int i = 0, j = 0; (i < len) && (j < blen); ) {
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uint32_t bit32 = data[i++] << 16;
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bit32 += (i++ < len ? data[i - 1] : 0) << 8;
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bit32 += i++ < len ? data[i - 1] : 0;
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buf[j++] = alphabet[(bit32 >> 18) & 0x3f];
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buf[j++] = alphabet[(bit32 >> 12) & 0x3f];
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buf[j++] = (i == (len + 2)) ? '=' : alphabet[(bit32 >> 6) & 0x3f];
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buf[j++] = (i >= (len + 1)) ? '=' : alphabet[bit32 & 0x3f];
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}
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}
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int* Base64Converter::InitBase64Table(const std::string& alphabet) {
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assert(alphabet.size() == 64);
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static bool default_table_initialized = false;
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if ( alphabet == default_alphabet && default_table_initialized )
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return default_base64_table;
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int* base64_table = nullptr;
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if ( alphabet == default_alphabet ) {
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base64_table = default_base64_table;
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default_table_initialized = true;
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}
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else
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base64_table = new int[256];
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int i;
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for ( i = 0; i < 256; ++i )
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base64_table[i] = -1;
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for ( i = 0; i < 26; ++i ) {
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base64_table[int(alphabet[0 + i])] = i;
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base64_table[int(alphabet[26 + i])] = i + 26;
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}
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for ( i = 0; i < 10; ++i )
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base64_table[int(alphabet[52 + i])] = i + 52;
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// Casts to avoid compiler warnings.
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base64_table[int(alphabet[62])] = 62;
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base64_table[int(alphabet[63])] = 63;
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base64_table[int('=')] = 0;
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return base64_table;
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}
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Base64Converter::Base64Converter(Connection* arg_conn, const std::string& arg_alphabet) {
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if ( arg_alphabet.size() > 0 ) {
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assert(arg_alphabet.size() == 64);
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alphabet = arg_alphabet;
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}
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else {
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alphabet = default_alphabet;
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}
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base64_table = nullptr;
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base64_group_next = 0;
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base64_padding = base64_after_padding = 0;
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errored = 0;
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conn = arg_conn;
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}
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Base64Converter::~Base64Converter() {
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if ( base64_table != default_base64_table )
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delete[] base64_table;
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}
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int Base64Converter::Decode(int len, const char* data, int* pblen, char** pbuf) {
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int blen;
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char* buf;
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// Initialization of table on first_time call of Decode.
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if ( ! base64_table )
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base64_table = InitBase64Table(alphabet);
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if ( ! pbuf )
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reporter->InternalError("nil pointer to decoding result buffer");
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if ( *pbuf ) {
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buf = *pbuf;
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blen = *pblen;
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}
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else {
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// Estimate the maximal number of 3-byte groups needed,
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// plus 1 byte for the optional ending NUL.
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blen = int((len + base64_group_next + 3) / 4) * 3 + 1;
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*pbuf = buf = new char[blen];
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}
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int dlen = 0;
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while ( true ) {
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if ( base64_group_next == 4 ) {
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// For every group of 4 6-bit numbers,
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// write the decoded 3 bytes to the buffer.
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if ( base64_after_padding ) {
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if ( ++errored == 1 )
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IllegalEncoding("extra base64 groups after '=' padding are ignored");
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base64_group_next = 0;
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continue;
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}
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int num_octets = 3 - base64_padding;
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if ( buf + num_octets > *pbuf + blen )
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break;
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uint32_t bit32 = ((base64_group[0] & 0x3f) << 18) | ((base64_group[1] & 0x3f) << 12) |
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((base64_group[2] & 0x3f) << 6) | ((base64_group[3] & 0x3f));
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if ( --num_octets >= 0 )
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*buf++ = char((bit32 >> 16) & 0xff);
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if ( --num_octets >= 0 )
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*buf++ = char((bit32 >> 8) & 0xff);
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if ( --num_octets >= 0 )
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*buf++ = char((bit32) & 0xff);
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if ( base64_padding > 0 )
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base64_after_padding = 1;
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base64_group_next = 0;
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base64_padding = 0;
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}
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if ( dlen >= len )
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break;
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unsigned char c = (unsigned char)data[dlen];
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if ( c == '=' )
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++base64_padding;
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int k = base64_table[c];
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if ( k >= 0 )
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base64_group[base64_group_next++] = k;
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else {
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if ( ++errored == 1 )
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IllegalEncoding(util::fmt("character %d ignored by Base64 decoding", (int)c));
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}
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++dlen;
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}
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*pblen = buf - *pbuf;
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return dlen;
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}
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int Base64Converter::Done(int* pblen, char** pbuf) {
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const char* padding = "===";
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if ( base64_group_next != 0 ) {
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if ( base64_group_next < 4 )
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IllegalEncoding(
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util::fmt("incomplete base64 group, padding with %d bits of 0", (4 - base64_group_next) * 6));
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Decode(4 - base64_group_next, padding, pblen, pbuf);
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return -1;
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}
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if ( pblen )
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*pblen = 0;
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return 0;
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}
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void Base64Converter::IllegalEncoding(const char* msg) {
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// strncpy(error_msg, msg, sizeof(error_msg));
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if ( conn )
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conn->Weird("base64_illegal_encoding", msg);
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else
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reporter->Error("%s", msg);
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}
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String* decode_base64(const String* s, const String* a, Connection* conn) {
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if ( a && a->Len() != 0 && a->Len() != 64 ) {
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reporter->Error("base64 decoding alphabet is not 64 characters: %s", a->CheckString());
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return nullptr;
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}
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int buf_len = int((s->Len() + 3) / 4) * 3 + 1;
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int rlen2, rlen = buf_len;
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char *rbuf2, *rbuf = new char[rlen];
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Base64Converter dec(conn, a ? a->CheckString() : "");
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dec.Decode(s->Len(), (const char*)s->Bytes(), &rlen, &rbuf);
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if ( dec.Errored() )
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goto err;
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rlen2 = buf_len - rlen;
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rbuf2 = rbuf + rlen;
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// Done() returns -1 if there isn't enough padding, but we just ignore
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// it.
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dec.Done(&rlen2, &rbuf2);
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rlen += rlen2;
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rbuf[rlen] = '\0';
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return new String(true, (u_char*)rbuf, rlen);
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err:
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delete[] rbuf;
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return nullptr;
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}
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String* encode_base64(const String* s, const String* a, Connection* conn) {
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if ( a && a->Len() != 0 && a->Len() != 64 ) {
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reporter->Error("base64 alphabet is not 64 characters: %s", a->CheckString());
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return nullptr;
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}
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char* outbuf = nullptr;
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int outlen = 0;
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Base64Converter enc(conn, a ? a->CheckString() : "");
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enc.Encode(s->Len(), (const unsigned char*)s->Bytes(), &outlen, &outbuf);
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return new String(true, (u_char*)outbuf, outlen);
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}
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} // namespace zeek::detail
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