/*
 * TLS module
 *
 * Copyright (C) 2005,2006 iptelorg GmbH
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*! \defgroup tls Kamailio TLS support
 *
 * This modules implements SIP over TCP with TLS encryption.
 * Make sure you read the README file that describes configuration
 * of TLS for single servers and servers hosting multiple domains,
 * and thus using multiple SSL/TLS certificates.
 *
 *
 */
/*!
 * \file
 * \brief Kamailio TLS support :: Initialization
 * \ingroup tls
 * Module: \ref tls
 */



#include <stdio.h>
#include <sys/types.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netinet/ip.h>
#include <unistd.h>
#include <string.h>
#include <wolfssl/options.h>
#include <wolfssl/ssl.h>

#include "../../core/dprint.h"
#include "../../core/mem/shm_mem.h"
#include "../../core/tcp_init.h"
#include "../../core/socket_info.h"
#include "../../core/pt.h"
#include "../../core/cfg/cfg.h"
#include "../../core/cfg/cfg_ctx.h"
#include "tls_verify.h"
#include "tls_domain.h"
#include "tls_util.h"
#include "tls_wolfssl_mod.h"
#include "tls_init.h"
#include "tls_ct_wrq.h"
#include "tls_cfg.h"

/* will be set to 1 when the TLS env is initialized to make destroy safe */
static int tls_mod_preinitialized = 0;
static int tls_mod_initialized = 0;

#define TLS_COMP_SUPPORT
#define TLS_KERBEROS_SUPPORT

sr_tls_methods_t sr_tls_methods[TLS_METHOD_MAX];

#ifdef NO_TLS_MALLOC_DBG
#undef TLS_MALLOC_DBG /* extra malloc debug info from openssl */
#endif /* NO_TLS_MALLOC_DBG */

/*
 * Wrappers around SER shared memory functions
 * (which can be macros)
 */
#ifdef TLS_MALLOC_DBG
#warning "tls module compiled with malloc debugging info (extra overhead)"
#include <execinfo.h>

/*
#define RAND_NULL_MALLOC (1024)
#define NULL_GRACE_PERIOD 10U
*/



inline static char* buf_append(char* buf, char* end, char* str, int str_len)
{
	if ( (buf+str_len)<end){
		memcpy(buf, str, str_len);
		return buf+str_len;
	}
	return 0;
}


inline static int backtrace2str(char* buf, int size)
{
	void* bt[32];
	int bt_size, i;
	char** bt_strs;
	char* p;
	char* end;
	char* next;
	char* s;
	char* e;

	p=buf; end=buf+size;
	bt_size=backtrace(bt, sizeof(bt)/sizeof(bt[0]));
	bt_strs=backtrace_symbols(bt, bt_size);
	if (bt_strs){
		p=buf; end=buf+size;
		/*if (bt_size>16) bt_size=16;*/ /* go up only 12 entries */
		for (i=3; i< bt_size; i++){
			/* try to isolate only the function name*/
			s=strchr(bt_strs[i], '(');
			if (s && ((e=strchr(s, ')'))!=0)){
				s++;
			}else if ((s=strchr(bt_strs[i], '['))!=0){
				e=s+strlen(s);
			}else{
				s=bt_strs[i]; e=s+strlen(s); /* add thw whole string */
			}
			next=buf_append(p, end, s, (int)(long)(e-s));
			if (next==0) break;
			else p=next;
			if (p<end){
				*p=':'; /* separator */
				p++;
			}else break;
		}
		if (p==buf){
			*p=0;
			p++;
		}else
			*(p-1)=0;
		free(bt_strs);
	}
	return (int)(long)(p-buf);
}

static void* ser_malloc(size_t size, const char* file, int line)
{
	void  *p;
	char bt_buf[1024];
	int s;
#ifdef RAND_NULL_MALLOC
	static ticks_t st=0;

	/* start random null returns only after
	 * NULL_GRACE_PERIOD from first call */
	if (st==0) st=get_ticks();
	if (((get_ticks()-st)<NULL_GRACE_PERIOD) || (random()%RAND_NULL_MALLOC)){
#endif
		s=backtrace2str(bt_buf, sizeof(bt_buf));
		/* ugly hack: keep the bt inside the alloc'ed fragment */
		p=_shm_malloc(size+s, file, "via ser_malloc", line);
		if (p==0){
			LM_CRIT("tls - ser_malloc(%d)[%s:%d]==null, bt: %s\n",
					size, file, line, bt_buf);
		}else{
			memcpy(p+size, bt_buf, s);
			((struct qm_frag*)((char*)p-sizeof(struct qm_frag)))->func=
				p+size;
		}
#ifdef RAND_NULL_MALLOC
	}else{
		p=0;
		backtrace2str(bt_buf, sizeof(bt_buf));
		LM_CRIT("tls - random ser_malloc(%d)[%s:%d] returning null - bt: %s\n",
				size, file, line, bt_buf);
	}
#endif
	return p;
}


static void* ser_realloc(void *ptr, size_t size, const char* file, int line)
{
	void  *p;
	char bt_buf[1024];
	int s;
#ifdef RAND_NULL_MALLOC
	static ticks_t st=0;

	/* start random null returns only after
	 * NULL_GRACE_PERIOD from first call */
	if (st==0) st=get_ticks();
	if (((get_ticks()-st)<NULL_GRACE_PERIOD) || (random()%RAND_NULL_MALLOC)){
#endif
		s=backtrace2str(bt_buf, sizeof(bt_buf));
		p=_shm_realloc(ptr, size+s, file, "via ser_realloc", line);
		if (p==0){
			LM_CRIT("tls - ser_realloc(%p, %d)[%s:%d]==null, bt: %s\n",
					ptr, size, file, line, bt_buf);
		}else{
			memcpy(p+size, bt_buf, s);
			((struct qm_frag*)((char*)p-sizeof(struct qm_frag)))->func=
				p+size;
		}
#ifdef RAND_NULL_MALLOC
	}else{
		p=0;
		backtrace2str(bt_buf, sizeof(bt_buf));
		LM_CRIT("tls - random ser_realloc(%p, %d)[%s:%d]"
				" returning null - bt: %s\n", ptr, size, file, line,
				bt_buf);
	}
#endif
	return p;
}

#else /*TLS_MALLOC_DBG */

// up align memory allocations to 16 bytes for
// wolfSSL --enable-aligndata=yes (the default)
static const int MAX_ALIGN = __alignof__(max_align_t);

static void* ser_malloc(size_t size)
{
	char* ptr =  shm_malloc(size + 2*MAX_ALIGN);
	int pad = MAX_ALIGN - ((long) ptr % MAX_ALIGN);

	*(size_t*)ptr = size;

	memset(ptr + MAX_ALIGN, pad, pad);
	return ptr + MAX_ALIGN + pad;
}

static void* ser_realloc(void *ptr, size_t new_size)
{
	if(!ptr) return ser_malloc(new_size);

	int pad = *((unsigned char*)ptr - 1);
	unsigned char *real_ptr = (unsigned char*)ptr - pad - MAX_ALIGN;
	int size = *(size_t*)real_ptr;

	char *new_ptr = shm_realloc(real_ptr, new_size+2*MAX_ALIGN);
	*(size_t*)new_ptr = new_size;
	int new_pad = MAX_ALIGN - ((long) new_ptr % MAX_ALIGN);
	if (new_pad != pad) {
		memmove(new_ptr + MAX_ALIGN + new_pad, new_ptr + MAX_ALIGN + pad, new_size);
		memset(new_ptr + MAX_ALIGN, new_pad, new_pad);
	}
		
	return new_ptr + MAX_ALIGN + new_pad;
}
#endif /* LIBRESSL_VERSION_NUMBER */

static void ser_free(void *ptr)
{
	if (ptr) {
		int pad = *((unsigned char *)ptr - 1);
		shm_free((unsigned char*)ptr - pad  - MAX_ALIGN);
	}
}


/*
 * Initialize TLS socket
 */
int tls_h_init_si_f(struct socket_info *si)
{
	int ret;
	/*
	 * reuse tcp initialization
	 */
	ret = tcp_init(si);
	if (ret != 0) {
		LM_ERR("Error while initializing TCP part of TLS socket %.*s:%d\n",
				si->address_str.len, si->address_str.s, si->port_no);
		goto error;
	}

	si->proto = PROTO_TLS;
	return 0;

error:
	if (si->socket != -1) {
		close(si->socket);
		si->socket = -1;
	}
	return ret;
}



/*
 * initialize ssl methods
 */
static void init_ssl_methods(void)
{
	/* openssl 1.1.0+ */
	memset(sr_tls_methods, 0, sizeof(sr_tls_methods));

	/* any SSL/TLS version */
	sr_tls_methods[TLS_USE_SSLv23_cli - 1].TLSMethod = TLS_client_method();
	sr_tls_methods[TLS_USE_SSLv23_srv - 1].TLSMethod = TLS_server_method();
	sr_tls_methods[TLS_USE_SSLv23 - 1].TLSMethod = TLS_method();

#ifndef OPENSSL_NO_SSL3_METHOD
	sr_tls_methods[TLS_USE_SSLv3_cli - 1].TLSMethod = TLS_client_method();
	sr_tls_methods[TLS_USE_SSLv3_cli - 1].TLSMethodMin = SSL3_VERSION;
	sr_tls_methods[TLS_USE_SSLv3_cli - 1].TLSMethodMax = SSL3_VERSION;
	sr_tls_methods[TLS_USE_SSLv3_srv - 1].TLSMethod = TLS_server_method();
	sr_tls_methods[TLS_USE_SSLv3_srv - 1].TLSMethodMin = SSL3_VERSION;
	sr_tls_methods[TLS_USE_SSLv3_srv - 1].TLSMethodMax = SSL3_VERSION;
	sr_tls_methods[TLS_USE_SSLv3 - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_SSLv3 - 1].TLSMethodMin = SSL3_VERSION;
	sr_tls_methods[TLS_USE_SSLv3 - 1].TLSMethodMax = SSL3_VERSION;
#endif

	sr_tls_methods[TLS_USE_TLSv1_cli - 1].TLSMethod = TLS_client_method();
	sr_tls_methods[TLS_USE_TLSv1_cli - 1].TLSMethodMin = TLS1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_cli - 1].TLSMethodMax = TLS1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_srv - 1].TLSMethod = TLS_server_method();
	sr_tls_methods[TLS_USE_TLSv1_srv - 1].TLSMethodMin = TLS1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_srv - 1].TLSMethodMax = TLS1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1 - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1 - 1].TLSMethodMin = TLS1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1 - 1].TLSMethodMax = TLS1_VERSION;

	sr_tls_methods[TLS_USE_TLSv1_1_cli - 1].TLSMethod = TLS_client_method();
	sr_tls_methods[TLS_USE_TLSv1_1_cli - 1].TLSMethodMin = TLS1_1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_1_cli - 1].TLSMethodMax = TLS1_1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_1_srv - 1].TLSMethod = TLS_server_method();
	sr_tls_methods[TLS_USE_TLSv1_1_srv - 1].TLSMethodMin = TLS1_1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_1_srv - 1].TLSMethodMax = TLS1_1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_1 - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1_1 - 1].TLSMethodMin = TLS1_1_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_1 - 1].TLSMethodMax = TLS1_1_VERSION;

	sr_tls_methods[TLS_USE_TLSv1_2_cli - 1].TLSMethod = TLS_client_method();
	sr_tls_methods[TLS_USE_TLSv1_2_cli - 1].TLSMethodMin = TLS1_2_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_2_cli - 1].TLSMethodMax = TLS1_2_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_2_srv - 1].TLSMethod = TLS_server_method();
	sr_tls_methods[TLS_USE_TLSv1_2_srv - 1].TLSMethodMin = TLS1_2_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_2_srv - 1].TLSMethodMax = TLS1_2_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_2 - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1_2 - 1].TLSMethodMin = TLS1_2_VERSION;
	sr_tls_methods[TLS_USE_TLSv1_2 - 1].TLSMethodMax = TLS1_2_VERSION;

	/* ranges of TLS versions (require a minimum TLS version) */
	sr_tls_methods[TLS_USE_TLSv1_PLUS - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1_PLUS - 1].TLSMethodMin = TLS1_VERSION;

	sr_tls_methods[TLS_USE_TLSv1_1_PLUS - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1_1_PLUS - 1].TLSMethodMin = TLS1_1_VERSION;

	sr_tls_methods[TLS_USE_TLSv1_2_PLUS - 1].TLSMethod = TLS_method();
	sr_tls_methods[TLS_USE_TLSv1_2_PLUS - 1].TLSMethodMin = TLS1_2_VERSION;
}


/*
 * Fix openssl compression bugs if necessary
 */
static int init_tls_compression(void)
{
	return 0;
}


/**
 * tls pre-init function
 * - executed when module is loaded
 */
int tls_pre_init(void)
{
	void *(*mf)(size_t, const char *, int) = NULL;
	void *(*rf)(void *, size_t, const char *, int) = NULL;
	void (*ff)(void *, const char *, int) = NULL;

#ifdef KSR_LIBSSL_STATIC
	LM_INFO("libssl linked mode: static\n");
#endif

	/*
	 * this has to be called before any function calling CRYPTO_malloc,
	 * CRYPTO_malloc will set allow_customize in openssl to 0
	 */
	// CRYPTO_get_mem_functions(&mf, &rf, &ff);
	LM_DBG("initial memory functions - malloc: %p realloc: %p free: %p\n",
			mf, rf, ff);
	mf = NULL;
	rf = NULL;
	ff = NULL;
	if (wolfSSL_SetAllocators(ser_malloc, ser_free, ser_realloc)) {
		LM_ERR("Unable to set the memory allocation functions\n");
		// CRYPTO_get_mem_functions(&mf, &rf, &ff);
		LM_ERR("libssl current mem functions - m: %p r: %p f: %p\n",
					mf, rf, ff);
		LM_ERR("module mem functions - m: %p r: %p f: %p\n",
					ser_malloc, ser_realloc, ser_free);
		LM_ERR("Be sure tls module is loaded before any other module using"
				" libssl (can be loaded first to be safe)\n");
		return -1;
	}
	LM_DBG("updated memory functions - malloc: %p realloc: %p free: %p\n",
			ser_malloc, ser_realloc, ser_free);

	init_tls_compression();
	return 0;
}

/**
 * tls mod pre-init function
 * - executed before any mod_init()
 */
int tls_h_mod_pre_init_f(void)
{
	if(tls_mod_preinitialized==1) {
		LM_DBG("already mod pre-initialized\n");
		return 0;
	}
	LM_DBG("preparing tls env for modules initialization\n");

	LM_DBG("preparing tls env for modules initialization (libssl >=1.1)\n");
	wolfSSL_OPENSSL_init_ssl(0, NULL);
	wolfSSL_load_error_strings();
	tls_mod_preinitialized=1;
	return 0;
}

/*
 * First step of TLS initialization
 */
int tls_h_mod_init_f(void)
{
	if(tls_mod_initialized == 1) {
		LM_DBG("already initialized\n");
		return 0;
	}
	LM_DBG("initializing tls system\n");

	init_ssl_methods();
	tls_mod_initialized = 1;
	return 0;
}


/*
 * Make sure that all server domains in the configuration have corresponding
 * listening socket in SER
 */
int tls_check_sockets(tls_domains_cfg_t* cfg)
{
	tls_domain_t* d;

	if (!cfg) return 0;

	d = cfg->srv_list;
	while(d) {
		if (d->ip.len && !find_si(&d->ip, d->port, PROTO_TLS)) {
			LM_ERR("%s: No listening socket found\n", tls_domain_str(d));
			return -1;
		}
		d = d->next;
	}
	return 0;
}


/*
 * TLS cleanup when application exits
 */
void tls_h_mod_destroy_f(void)
{
	LM_DBG("tls module final tls destroy\n");
	if(tls_mod_preinitialized > 0)
		ERR_free_strings();
	/* TODO: free all the ctx'es */
	tls_destroy_cfg();
	tls_ct_wq_destroy();
	/* explicit execution of libssl cleanup to avoid being executed again
	 * by atexit(), when shm is gone */
	LM_DBG("executing openssl v1.1+ cleanup\n");
	wolfSSL_Cleanup();
}