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packet.c: improve message parsing (#402)

* packet.c: improve parsing of packets

file: packet.c

notes:
Use _libssh2_get_string API in SSH_MSG_DEBUG/SSH_MSG_DISCONNECT. Additional uint32 bounds check in SSH_MSG_GLOBAL_REQUEST.
Этот коммит содержится в:
Will Cosgrove 2019-08-30 09:57:38 -07:00 коммит произвёл GitHub
родитель e5732992b1
Коммит dedcbd106f
Не найден ключ, соответствующий данной подписи
Идентификатор ключа GPG: 4AEE18F83AFDEB23

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@ -419,8 +419,8 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
size_t datalen, int macstate)
{
int rc = 0;
char *message = NULL;
char *language = NULL;
unsigned char *message = NULL;
unsigned char *language = NULL;
size_t message_len = 0;
size_t language_len = 0;
LIBSSH2_CHANNEL *channelp = NULL;
@ -472,33 +472,23 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
case SSH_MSG_DISCONNECT:
if(datalen >= 5) {
size_t reason = _libssh2_ntohu32(data + 1);
uint32_t reason = 0;
struct string_buf buf;
buf.data = (unsigned char *)data;
buf.dataptr = buf.data;
buf.len = datalen;
buf.dataptr++; /* advance past type */
if(datalen >= 9) {
message_len = _libssh2_ntohu32(data + 5);
_libssh2_get_u32(&buf, &reason);
_libssh2_get_string(&buf, &message, &message_len);
_libssh2_get_string(&buf, &language, &language_len);
if(message_len < datalen-13) {
/* 9 = packet_type(1) + reason(4) + message_len(4) */
message = (char *) data + 9;
language_len =
_libssh2_ntohu32(data + 9 + message_len);
language = (char *) data + 9 + message_len + 4;
if(language_len > (datalen-13-message_len)) {
/* bad input, clear info */
language = message = NULL;
language_len = message_len = 0;
}
}
else
/* bad size, clear it */
message_len = 0;
}
if(session->ssh_msg_disconnect) {
LIBSSH2_DISCONNECT(session, reason, message,
message_len, language, language_len);
LIBSSH2_DISCONNECT(session, reason, (const char *)message,
message_len, (const char *)language,
language_len);
}
_libssh2_debug(session, LIBSSH2_TRACE_TRANS,
"Disconnect(%d): %s(%s)", reason,
message, language);
@ -539,24 +529,24 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
int always_display = data[1];
if(datalen >= 6) {
message_len = _libssh2_ntohu32(data + 2);
struct string_buf buf;
buf.data = (unsigned char *)data;
buf.dataptr = buf.data;
buf.len = datalen;
buf.dataptr += 2; /* advance past type & always display */
if(message_len <= (datalen - 10)) {
/* 6 = packet_type(1) + display(1) + message_len(4) */
message = (char *) data + 6;
language_len = _libssh2_ntohu32(data + 6 +
message_len);
if(language_len <= (datalen - 10 - message_len))
language = (char *) data + 10 + message_len;
}
_libssh2_get_string(&buf, &message, &message_len);
_libssh2_get_string(&buf, &language, &language_len);
}
if(session->ssh_msg_debug) {
LIBSSH2_DEBUG(session, always_display, message,
message_len, language, language_len);
LIBSSH2_DEBUG(session, always_display,
(const char *)message,
message_len, (const char *)language,
language_len);
}
}
/*
* _libssh2_debug will actually truncate this for us so
* that it's not an inordinate about of data
@ -579,7 +569,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
uint32_t len = 0;
unsigned char want_reply = 0;
len = _libssh2_ntohu32(data + 1);
if(datalen >= (6 + len)) {
if((len <= (UINT_MAX - 6)) && (datalen >= (6 + len))) {
want_reply = data[5 + len];
_libssh2_debug(session,
LIBSSH2_TRACE_CONN,