### Description

a tls connection uses 52104 bytes. Among these memory, tcp_connection structure use 776 bytes and tcp_rd_buf use 6000 bytes, and the left part (45328 bytes) are all about SSL session with crypto.

### Expected behavior kamailio does some optimization for self defined BIO_TYPE_SOURCE_SINK bio type, to save more memory

#### Actual observed behavior among this 45328 bytes, the biggest parts are BIO read buffer(16KB) and BIO write buffer(16KB). currently kamailio uses BIO_TYPE_SOURCE_SINK type bio, which needs kamailio manage the buffer by itself (there is no optimization). While nginx uses BIO_TYPE_MEM type bio, which is a openssl's internal bio type with memory optimization. As a result, nginx use less memory to accept more TLS connections than kamailio

#### Debugging Data None

#### Log Messages Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1219]: tlsf_sums(): pool (0x7f1a3eec1000) summarizing all alloc'ed. fragments: Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 2 size= 336 bytes from tls: tls_init.c: crypto/evp/evp_enc.c(43) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 80 bytes from tls: tls_init.c: crypto/bn/bn_blind.c(36) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 3 size= 360 bytes from tls: tls_init.c: crypto/bn/bn_mont.c(232) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 2 size= 1456 bytes from tls: tls_init.c: crypto/evp/evp_enc.c(129) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 120 bytes from tls: tls_init.c: ssl/t1_lib.c(1784) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_init.c: ssl/statem/extensions.c(959) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 2 size= 112 bytes from tls: tls_init.c: ssl/t1_lib.c(1811) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_init.c: ssl/statem/../packet_local.h(462) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_init.c: ssl/statem/../packet_local.h(485) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 640 bytes from tls: tls_init.c: ssl/ssl_sess.c(72) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 144 bytes from tls: tls_init.c: ssl/packet_local.h(462) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 224 bytes from tls: tls_init.c: crypto/evp/digest.c(139) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 3 size= 168 bytes from tls: tls_init.c: crypto/evp/digest.c(62) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 16496 bytes from tls: tls_init.c: ssl/record/ssl3_buffer.c(124) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 16712 bytes from tls: tls_init.c: ssl/record/ssl3_buffer.c(63) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 6280 bytes from tls: tls_init.c: ssl/ssl_lib.c(691) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 6776 bytes from core: tcp_main.c: tcpconn_new(1148) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_init.c: tls_bio.c(184) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 120 bytes from tls: tls_init.c: crypto/bio/bio_lib.c(73) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 536 bytes from tls: tls_init.c: ssl/ssl_cert.c(76) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_init.c: ssl/ssl_lib.c(793) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 72 bytes from tls: tls_init.c: crypto/bio/bio_meth.c(41) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 96 bytes from tls: tls_init.c: crypto/bio/bio_meth.c(38) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 1040 bytes from tls: tls_init.c: ssl/s3_lib.c(3296) Mar 30 19:46:46 localhost.localdomain sipproxy[2273]: INFO: <core> [mem/tlsf_malloc.c:1235]: tlsf_sums(): count= 1 size= 56 bytes from tls: tls_server.c: tls_complete_init(229)

#### SIP Traffic None

### Possible Solutions None

### Additional Information

[root@ip-10-23-0-191 ec2-user]# /opt/kamailio/sbin/kamailio -v version: kamailio 4.4.7 (aarch64/linux) flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT-NOSMP, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled on 12:18:05 Mar 28 2024 with gcc 7.3.1

* **Operating System**: Linux localhost.localdomain 4.18.0-425.3.1.el8.x86_64 #1 SMP Tue Nov 8 14:08:25 EST 2022 x86_64 x86_64 x86_64 GNU/Linux