Fix memory leaks detected during testing

[JavierJF]

• A clear description of the issue

The following two memory leaks have been detected during testing:

First leak

Leak is directly tied to handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE,
related to memory allocated to client_addr. As we can see by the log:

2021-09-10 16:13:55 MySQL_Session.cpp:5098:handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(): [ERROR] ProxySQL Error: Access denied for user 'inv_user'@'10.200.1.2' (using password: YES)
2021-09-10 16:13:56 MySQL_Session.cpp:5098:handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(): [ERROR] ProxySQL Error: Access denied for user 'inv_user'@'10.200.1.2' (using password: YES)
2021-09-10 16:13:56 MySQL_Session.cpp:5098:handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(): [ERROR] ProxySQL Error: Access denied for user 'inv_user'@'10.200.1.2' (using password: YES)
2021-09-10 16:13:57 MySQL_Session.cpp:5098:handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(): [ERROR] ProxySQL Error: Access denied for user 'inv_user'@'10.200.1.2' (using password: YES)

==1202933==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 44 byte(s) in 4 object(s) allocated from:
    #0 0x7f1340b783f9 in __interceptor_strdup /build/gcc/src/gcc/libsanitizer/asan/asan_interceptors.cpp:454
    #1 0x565348b76756 in MySQL_Session::handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(_PtrSize_t*, bool*) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:5059
    #2 0x565348b61e4a in MySQL_Session::get_pkts_from_client(bool&, _PtrSize_t&) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:3416
    #3 0x565348b6bdd1 in MySQL_Session::handler() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:4254
    #4 0x565348aeb2a0 in MySQL_Thread::process_all_sessions() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3539
    #5 0x565348ae51a3 in MySQL_Thread::run() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3051
    #6 0x565348902f6e in mysql_worker_thread_func(void*) /home/javjarfer/Projects/proxysql_v2.X.0/src/main.cpp:417
    #7 0x7f1340903258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Direct leak of 36 byte(s) in 1 object(s) allocated from:
    #0 0x7f1340bd3279 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x565348aaf5d4 in MySQL_Data_Stream::buffer2array() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:975
    #2 0x565348aad8ff in MySQL_Data_Stream::read_pkts() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:892
    #3 0x565348c36fd5 in child_mysql(void*) /home/javjarfer/Projects/proxysql_v2.X.0/lib/ProxySQL_Admin.cpp:4908
    #4 0x7f1340903258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Leak is related with failed connections. Same result isn't achieved for non-failing
connections.

Second leak

Leak is related with SSL connections:

==1199044==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 252 byte(s) in 7 object(s) allocated from:
    #0 0x7f3fb412b279 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x5612e29f05d4 in MySQL_Data_Stream::buffer2array() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:975
    #2 0x5612e29ee8ff in MySQL_Data_Stream::read_pkts() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:892
    #3 0x5612e2a28fa7 in MySQL_Thread::process_data_on_data_stream(MySQL_Data_Stream*, unsigned int) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3277
    #4 0x5612e2a23dd0 in MySQL_Thread::ProcessAllMyDS_AfterPoll() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:2793
    #5 0x5612e2a25f8d in MySQL_Thread::run() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3035
    #6 0x5612e2843f6e in mysql_worker_thread_func(void*) /home/javjarfer/Projects/proxysql_v2.X.0/src/main.cpp:417
    #7 0x7f3fb3e5b258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Direct leak of 36 byte(s) in 1 object(s) allocated from:
    #0 0x7f3fb412b279 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x5612e29f05d4 in MySQL_Data_Stream::buffer2array() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:975
    #2 0x5612e29ee8ff in MySQL_Data_Stream::read_pkts() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:892
    #3 0x5612e2b77fd5 in child_mysql(void*) /home/javjarfer/Projects/proxysql_v2.X.0/lib/ProxySQL_Admin.cpp:4908
    #4 0x7f3fb3e5b258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

• ProxySQL version

v2.x

• OS version

NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
BUILD_ID=rolling

• The steps to reproduce the issue

The provided script should be enough to reproduce both issues, sanitizer output should be:

Direct leak of 108 byte(s) in 3 object(s) allocated from:
    #0 0x7f1985b0d279 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x56403038a5d4 in MySQL_Data_Stream::buffer2array() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:975
    #2 0x5640303888ff in MySQL_Data_Stream::read_pkts() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:892
    #3 0x5640303c2fa7 in MySQL_Thread::process_data_on_data_stream(MySQL_Data_Stream*, unsigned int) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3277
    #4 0x5640303bddd0 in MySQL_Thread::ProcessAllMyDS_AfterPoll() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:2793
    #5 0x5640303bff8d in MySQL_Thread::run() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3035
    #6 0x5640301ddf6e in mysql_worker_thread_func(void*) /home/javjarfer/Projects/proxysql_v2.X.0/src/main.cpp:417
    #7 0x7f198583d258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Direct leak of 108 byte(s) in 3 object(s) allocated from:
    #0 0x7f1985b0d279 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x56403038a5d4 in MySQL_Data_Stream::buffer2array() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:975
    #2 0x5640303888ff in MySQL_Data_Stream::read_pkts() /home/javjarfer/Projects/proxysql_v2.X.0/lib/mysql_data_stream.cpp:892
    #3 0x564030511fd5 in child_mysql(void*) /home/javjarfer/Projects/proxysql_v2.X.0/lib/ProxySQL_Admin.cpp:4908
    #4 0x7f198583d258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Direct leak of 33 byte(s) in 3 object(s) allocated from:
    #0 0x7f1985ab23f9 in __interceptor_strdup /build/gcc/src/gcc/libsanitizer/asan/asan_interceptors.cpp:454
    #1 0x564030451756 in MySQL_Session::handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE(_PtrSize_t*, bool*) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:5059
    #2 0x56403043ce4a in MySQL_Session::get_pkts_from_client(bool&, _PtrSize_t&) /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:3416
    #3 0x564030446dd1 in MySQL_Session::handler() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Session.cpp:4254
    #4 0x5640303c62a0 in MySQL_Thread::process_all_sessions() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3539
    #5 0x5640303c01a3 in MySQL_Thread::run() /home/javjarfer/Projects/proxysql_v2.X.0/lib/MySQL_Thread.cpp:3051
    #6 0x5640301ddf6e in mysql_worker_thread_func(void*) /home/javjarfer/Projects/proxysql_v2.X.0/src/main.cpp:417
    #7 0x7f198583d258 in start_thread (/usr/lib/libpthread.so.0+0x9258)

Script:
reproduce_leaks.sh.tar.gz