nat_helper.c File Reference

---

Detailed Description

Proxy-CSCF - NAT helper for signalling.

Note:

Taken from SER nathelper module

Author:

adapted for the pcscf module by Marius Corici mco -at- fokus dot fraunhofer dot de

Definition in file nat_helper.c.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "../../parser/msg_parser.h"
#include "../../msg_translator.h"
#include "../../parser/parser_f.h"
#include "../../parser/contact/contact.h"
#include "../../parser/contact/parse_contact.h"
#include "../../parser/parse_uri.h"
#include "../../parser/hf.h"
#include "../../ut.h"
#include "../../forward.h"
#include "mod.h"
#include "registrar_storage.h"
#include "nat_helper.h"

Go to the source code of this file.

Defines
#define	READ(val)   (*(val + 0) + (*(val + 1) << 8) + (*(val + 2) << 16) + (*(val + 3) << 24))
#define	advance(_ptr, _n, _str, _error)
#define	one_of_16(_x, _t)
#define	one_of_8(_x, _t)
Functions
int	is1918addr (str *saddr)
	Test if IP address pointed to by saddr belongs to RFC1918 networks.
char *	ser_memmem (const void *b1, const void *b2, size_t len1, size_t len2)
	ser_memmem() returns the location of the first occurrence of data pattern b2 of size len2 in memory block b1 of size len1 or NULL if none is found.
int	nat_prepare_1918addr ()
	Fixes the 1918 private networks addresses.
static int	get_contact_uri (struct sip_msg *_m, struct sip_uri *uri, contact_t **_c)
	Extract URI from the Contact header field.
static int	via_1918 (struct sip_msg *msg)
	Checks if the first Via in the message is a 1918 address.
int	nat_uac_test (struct sip_msg *msg)
	Tests if the message was received from behind a NAT.
r_nat_dest *	nat_msg_origin (struct sip_msg *msg)
	Retrieves the originating source of a message into a r_nat_dest structure.
int	requires_nat (struct sip_msg *msg)
	Finds if a NAT pinhole would be required to reach this user.
int	nat_send_ping (r_contact *c)
	Pings a contact to keep the NAT pinhole alive.
Variables
static const char	udp_ping [2] = { 10, 13}
	message to ping with - CRLF
int	pcscf_nat_enable
	whether to enable NAT
int	pcscf_nat_ping
	whether to ping anything
int	pcscf_nat_pingall
	whether to ping also the UA that don't look like being behind a NAT
int	pcscf_nat_detection_type
	the NAT detection tests
network_t	nets_1918 []

---

Define Documentation

#define READ

(

val

)

(*(val + 0) + (*(val + 1) << 8) + (*(val + 2) << 16) + (*(val + 3) << 24))

Definition at line 248 of file nat_helper.c.

Referenced by check_content_type().

#define advance	(	_ptr,
		_n,
		_str,
		_error		)

Value:

do{\
        if ((_ptr)+(_n)>(_str).s+(_str).len)\
            goto _error;\
        (_ptr) = (_ptr) + (_n);\
    }while(0);

Definition at line 250 of file nat_helper.c.

Referenced by check_content_type().

#define one_of_16	(	_x,
		_t		)

Value:

(_x==_t[0]||_x==_t[15]||_x==_t[8]||_x==_t[2]||_x==_t[3]||_x==_t[4]\
    ||_x==_t[5]||_x==_t[6]||_x==_t[7]||_x==_t[1]||_x==_t[9]||_x==_t[10]\
    ||_x==_t[11]||_x==_t[12]||_x==_t[13]||_x==_t[14])

Definition at line 256 of file nat_helper.c.

Referenced by check_content_type().

#define one_of_8	(	_x,
		_t		)

Value:

(_x==_t[0]||_x==_t[7]||_x==_t[1]||_x==_t[2]||_x==_t[3]||_x==_t[4]\
    ||_x==_t[5]||_x==_t[6])

Definition at line 260 of file nat_helper.c.

Referenced by check_content_type().

---

Function Documentation

int is1918addr

(

str *

saddr

)

Test if IP address pointed to by saddr belongs to RFC1918 networks.

Parameters:

saddr

- string with address to check

Returns:

if the network is private one

Definition at line 278 of file nat_helper.c.

References network_t::cnetaddr, nets_1918, and NULL.

Referenced by via_1918().

                           {
    struct in_addr addr;
    uint32_t netaddr;
    int i, rval;
    char backup;

    rval = -1;
    backup = saddr->s[saddr->len];
    saddr->s[saddr->len] = '\0';
    if (inet_aton(saddr->s, &addr) != 1)
        goto is1918addr_end;
    netaddr = ntohl(addr.s_addr);
    for (i = 0; nets_1918[i].cnetaddr != NULL; i++) {
        if ((netaddr & nets_1918[i].mask) == nets_1918[i].netaddr) {
            rval = 1;
            goto is1918addr_end;
        }
    }
    rval = 0;

is1918addr_end:
    saddr->s[saddr->len] = backup;
    return rval;
}

char* ser_memmem	(	const void *	b1,
		const void *	b2,
		size_t	len1,
		size_t	len2
	)

ser_memmem() returns the location of the first occurrence of data pattern b2 of size len2 in memory block b1 of size len1 or NULL if none is found.

Obtained from NetBSD.

Definition at line 309 of file nat_helper.c.

References NULL.

Referenced by extract_mediaip(), extract_mediaport(), find_sdp_line(), and force_rtp_proxy2_f().

{
    /* Initialize search pointer */
    char *sp = (char *) b1;

    /* Initialize pattern pointer */
    char *pp = (char *) b2;

    /* Initialize end of search address space pointer */
    char *eos = sp + len1 - len2;

    /* Sanity check */
    if(!(b1 && b2 && len1 && len2))
        return NULL;

    while (sp <= eos) {
        if (*sp == *pp)
            if (memcmp(sp, pp, len2) == 0)
                return sp;

            sp++;
    }

    return NULL;
}

int nat_prepare_1918addr

(

)

Fixes the 1918 private networks addresses.

Definition at line 338 of file nat_helper.c.

References network_t::cnetaddr, network_t::mask, network_t::netaddr, nets_1918, and NULL.

Referenced by mod_init().

                           {
    int i;
    struct in_addr addr;
    
    /* Prepare 1918 networks list */
    for (i = 0; nets_1918[i].cnetaddr != NULL; i++) {
        if (inet_aton(nets_1918[i].cnetaddr, &addr) != 1)
            abort();
        nets_1918[i].netaddr = ntohl(addr.s_addr) & nets_1918[i].mask;
    }
    return 1;
}

static int get_contact_uri	(	struct sip_msg *	_m,
		struct sip_uri *	uri,
		contact_t **	_c
	)			[inline, static]

Extract URI from the Contact header field.

Parameters:

	_m	- the SIP message
	uri	- URI to fill
	_c	- contact to fill

Returns:

0 on success, -1 on error

Definition at line 358 of file nat_helper.c.

References NULL.

{

    if ((parse_headers(_m, HDR_CONTACT_F, 0) == -1) || !_m->contact)
        return -1;
    if (!_m->contact->parsed && parse_contact(_m->contact) < 0) {
        LOG(L_ERR, "get_contact_uri: Error while parsing Contact body\n");
        return -1;
    }
    *_c = ((contact_body_t*)_m->contact->parsed)->contacts;
    if (*_c == NULL) {
        LOG(L_DBG, "get_contact_uri: Error while parsing Contact body or star contact\n");
        return -1;
    }
    if (parse_uri((*_c)->uri.s, (*_c)->uri.len, uri) < 0 || uri->host.len <= 0) {
        LOG(L_ERR, "get_contact_uri: Error while parsing Contact URI\n");
        return -1;
    }
    return 0;
}

static int via_1918

(

struct sip_msg *

msg

)

[static]

Checks if the first Via in the message is a 1918 address.

Parameters:

msg

- the SIP message

Returns:

1 if it is, 0 if not

Definition at line 399 of file nat_helper.c.

References is1918addr().

Referenced by nat_uac_test().

                                          {
    return (is1918addr(&(msg->via1->host)) == 1) ? 1 : 0;
}

int nat_uac_test

(

struct sip_msg *

msg

)

Tests if the message was received from behind a NAT.

• tests received, contact and via

  Parameters:

  msg

  - the SIP message

Definition at line 408 of file nat_helper.c.

References NAT_UAC_TEST_RCVD, NAT_UAC_TEST_RPORT, NAT_UAC_TEST_V_1918, pcscf_nat_detection_type, pcscf_nat_pingall, and via_1918().

Referenced by nat_msg_origin(), and requires_nat().

                                       {

    if(pcscf_nat_pingall)
        return 1;
        
    if((pcscf_nat_detection_type && NAT_UAC_TEST_RPORT) && 
        (msg->rcv.src_port != (msg-> via1->port ? msg->via1->port:SIP_PORT)))
        return 1;
    
    if((pcscf_nat_detection_type & NAT_UAC_TEST_RCVD) && received_test(msg))
        return 1;
    
//  if((pcscf_nat_detection_type & NAT_UAC_TEST_C_1918) && contact_1918(msg))
        //return 1;
    
//  if((pcscf_nat_detection_type & NAT_UAC_TEST_S_1918) && sdp_1918(msg))
//      return 1;
        
    if((pcscf_nat_detection_type & NAT_UAC_TEST_V_1918) && via_1918(msg))
        return 1;
    
    return 0;
}

r_nat_dest* nat_msg_origin

(

struct sip_msg *

msg

)

Retrieves the originating source of a message into a r_nat_dest structure.

Parameters:

	msg	- the SIP message
	pinhole	- where to save to

Returns:

1 on success, -1 on error

Definition at line 438 of file nat_helper.c.

References M_NAME, _r_nat_dest::nat_addr, nat_uac_test(), NULL, pcscf_nat_enable, and pcscf_nat_pingall.

Referenced by update_contacts().

                                                 {
    r_nat_dest *pinhole=NULL;
    if (!pcscf_nat_enable) return NULL;
    if(pcscf_nat_pingall || nat_uac_test(msg)) {
        pinhole = shm_malloc(sizeof(r_nat_dest));
        if (pinhole == NULL) {
            LOG(L_ERR,"ERR:"M_NAME":nat_msg_origin:no memory\n");
            return NULL;
        }
        memcpy(&pinhole->nat_addr, &msg->rcv.src_ip, sizeof(struct ip_addr));
        pinhole -> nat_port = msg -> rcv.src_port;
    }
    return pinhole;
}

int requires_nat

(

struct sip_msg *

msg

)

Finds if a NAT pinhole would be required to reach this user.

Parameters:

msg

- the SIP message

Returns:

1 if yes, 0 if not

Definition at line 458 of file nat_helper.c.

References nat_uac_test(), pcscf_nat_enable, and pcscf_nat_pingall.

Referenced by P_save_location().

{
    return pcscf_nat_enable && (pcscf_nat_pingall || nat_uac_test(msg));
}

int nat_send_ping

(

r_contact *

c

)

Pings a contact to keep the NAT pinhole alive.

Parameters:

c

- the r_contact to ping

Returns:

1 on success, -1 on failure

Definition at line 469 of file nat_helper.c.

References M_NAME, _r_nat_dest::nat_addr, _r_nat_dest::nat_port, NULL, _r_contact::pinhole, _r_contact::transport, and udp_ping.

                                {
    struct dest_info dst;
    
    if(c->pinhole == NULL)
        return 1;
    if(c->transport != PROTO_UDP && c->transport != PROTO_NONE)
        return 1;
    init_dest_info(&dst);
    dst.proto = PROTO_UDP;
    
    memset(&(dst.to), 0, sizeof(union sockaddr_union));
    dst.to.s.sa_family=c->pinhole->nat_addr.af;
    switch(dst.to.s.sa_family) {
        case AF_INET6:
            memcpy(&dst.to.sin6.sin6_addr, c->pinhole->nat_addr.u.addr, c->pinhole->nat_addr.len);
            //dst.to.sin6.sin6_len=sizeof(struct sockaddr_in6);
            dst.to.sin6.sin6_port=htons(c->pinhole->nat_port);
            break;
        case AF_INET:
            memcpy(&dst.to.sin.sin_addr, c->pinhole->nat_addr.u.addr, c->pinhole->nat_addr.len);
            //dst.to.sin.sin_len=sizeof(struct sockaddr_in);
            dst.to.sin.sin_port=htons(c->pinhole->nat_port);
            break;
        default:
            LOG(L_CRIT,"CRIT:"M_NAME":nat_send_ping: unknown address family %d\n", dst.to.s.sa_family);
            return -1;
    }
    dst.send_sock=get_send_socket(0, &dst.to, PROTO_UDP);
    if(dst.send_sock == NULL) {
        LOG(L_ERR,"ERR:"M_NAME":nat_send_ping: cannot get sending socket\n");
        return -1;
    }
    udp_send(&dst, (char *)udp_ping, sizeof(udp_ping));
    return 1; 
}

---

Variable Documentation

const char udp_ping[2] = { 10, 13} [static]

message to ping with - CRLF

Definition at line 241 of file nat_helper.c.

Referenced by nat_send_ping().

int pcscf_nat_enable

whether to enable NAT

Definition at line 142 of file mod.c.

int pcscf_nat_ping

whether to ping anything

Definition at line 143 of file mod.c.

int pcscf_nat_pingall

whether to ping also the UA that don't look like being behind a NAT

Definition at line 144 of file mod.c.

int pcscf_nat_detection_type

the NAT detection tests

Definition at line 145 of file mod.c.

network_t nets_1918[]

Initial value:

 {
    {"10.0.0.0",    0, 0xffffffffu << 24},
    {"172.16.0.0",  0, 0xffffffffu << 20},
    {"192.168.0.0", 0, 0xffffffffu << 16},
    {NULL, 0, 0}
}

Definition at line 265 of file nat_helper.c.

Referenced by is1918addr(), nat_prepare_1918addr(), and rfc1918address().

---