/*

Copyright (C) 2010-2012 Paul Gardner-Stephen, Serval Project.

This program is free software; you can redistribute it and/or

modify it under the terms of the GNU General Public License

as published by the Free Software Foundation; either version 2

of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

*/

#include <sys/stat.h>

#include "serval.h"

#include "strbuf.h"

#include "overlay_buffer.h"

#include "overlay_address.h"

#include "overlay_packet.h"

#include "mdp_client.h"

struct profile_total mdp_stats={.name="overlay_mdp_poll"};

struct sched_ent mdp_abstract={

.function = overlay_mdp_poll,

.stats = &mdp_stats,

};

struct sched_ent mdp_named={

.function = overlay_mdp_poll,

.stats = &mdp_stats,

};

// is the SID entirely 0xFF?

#define is_broadcast(SID) is_all_matching(SID, SID_SIZE, 0xFF)

// is the SID entirely 0x00?

#define is_sid_any(SID) is_all_matching(SID, SID_SIZE, 0)

int overlay_mdp_setup_sockets()

{

struct sockaddr_un name;

int len;

name.sun_family = AF_UNIX;

#ifndef HAVE_LINUX_IF_H

/* Abstrack name space (i.e., non-file represented) unix domain sockets are a

linux-only thing. */

mdp_abstract.poll.fd = -1;

#else

if (mdp_abstract.poll.fd<=0) {

/* Abstract name space unix sockets is a special Linux thing, which is

convenient for us because Android is Linux, but does not have a shared

writable path that is on a UFS partition, so we cannot use traditional

named unix domain sockets. So the abstract name space gives us a solution. */

name.sun_path[0]=0;

/* XXX The 100 should be replaced with the actual maximum allowed.

Apparently POSIX requires it to be at least 100, but I would still feel

more comfortable with using the appropriate constant. */

snprintf(&name.sun_path[1],100,

confValueGet("mdp.socket",DEFAULT_MDP_SOCKET_NAME));

len = 1+strlen(&name.sun_path[1]) + sizeof(name.sun_family);

mdp_abstract.poll.fd = socket(AF_UNIX, SOCK_DGRAM, 0);

if (mdp_abstract.poll.fd>-1) {

int reuseP=1;

if (setsockopt( mdp_abstract.poll.fd, SOL_SOCKET, SO_REUSEADDR, &reuseP, sizeof(reuseP)) == -1) {

WARN_perror("setsockopt(SO_REUSEADDR)");

WARN("Could not set socket reuse addresses");

}

if (bind(mdp_abstract.poll.fd, (struct sockaddr *)&name, len) == -1) {

WARN_perror("bind");

close(mdp_abstract.poll.fd);

mdp_abstract.poll.fd = -1;

WARN("bind of abstract name space socket failed (not a problem on non-linux systems)");

}

int send_buffer_size=64*1024;

if (setsockopt(mdp_abstract.poll.fd, SOL_SOCKET, SO_SNDBUF, &send_buffer_size, sizeof(send_buffer_size)) == -1)

WARN_perror("setsockopt(SO_SNDBUF)");

mdp_abstract.poll.events = POLLIN;

watch(&mdp_abstract);

}

}

#endif

if (mdp_named.poll.fd<=0) {

if (!form_serval_instance_path(&name.sun_path[0], 100, "mdp.socket"))

return WHY("Cannot construct name of unix domain socket.");

unlink(&name.sun_path[0]);

len = 0+strlen(&name.sun_path[0]) + sizeof(name.sun_family)+1;

mdp_named.poll.fd = socket(AF_UNIX, SOCK_DGRAM, 0);

if (mdp_named.poll.fd>-1) {

int reuseP=1;

if(setsockopt( mdp_named.poll.fd, SOL_SOCKET, SO_REUSEADDR, &reuseP, sizeof(reuseP)) == -1) {

WARN_perror("setsockopt(SO_REUSEADDR)");

WARN("Could not set socket reuse addresses");

}

if (bind(mdp_named.poll.fd, (struct sockaddr *)&name, len) == -1) {

WARN_perror("bind");

close(mdp_named.poll.fd);

mdp_named.poll.fd = -1;

WARN("Could not bind named unix domain socket");

}

int send_buffer_size=64*1024;

if (setsockopt(mdp_named.poll.fd, SOL_SOCKET, SO_RCVBUF, &send_buffer_size, sizeof(send_buffer_size)) == -1)

WARN_perror("setsockopt(SO_RCVBUF)");

mdp_named.function = overlay_mdp_poll;

mdp_named.stats = &mdp_stats;

mdp_named.poll.events = POLLIN;

watch(&mdp_named);

}

}

return 0;

}

#define MDP_MAX_BINDINGS 100

#define MDP_MAX_SOCKET_NAME_LEN 110

struct mdp_binding{

};

struct mdp_binding mdp_bindings[MDP_MAX_BINDINGS];

int mdp_bindings_initialised=0;

int overlay_mdp_reply_error(int sock,

struct sockaddr_un *recvaddr,int recvaddrlen,

int error_number,char *message)

{

overlay_mdp_frame mdpreply;

mdpreply.packetTypeAndFlags=MDP_ERROR;

mdpreply.error.error=error_number;

if (error_number)

WHYF("MDP error, code #%d %s",error_number, message);

if (error_number==0||message)

snprintf(&mdpreply.error.message[0],128,"%s",message?message:"Success");

else{

snprintf(&mdpreply.error.message[0],128,"Error code #%d",error_number);

}

mdpreply.error.message[127]=0;

return overlay_mdp_reply(sock,recvaddr,recvaddrlen,&mdpreply);

}

int overlay_mdp_reply(int sock,struct sockaddr_un *recvaddr,int recvaddrlen,

overlay_mdp_frame *mdpreply)

{

int replylen;

if (!recvaddr) return 0;

replylen=overlay_mdp_relevant_bytes(mdpreply);

if (replylen<0) return WHY("Invalid MDP frame (could not compute length)");

errno=0;

int r=sendto(sock,(char *)mdpreply,replylen,0,

(struct sockaddr *)recvaddr,recvaddrlen);

if (r<replylen) {

WHY_perror("sendto(d)");

return WHYF("sendto() failed when sending MDP reply, sock=%d, r=%d", sock, r);

} else

if (0) DEBUGF("reply of %d bytes sent",r);

return 0;

}

int overlay_mdp_reply_ok(int sock,

struct sockaddr_un *recvaddr,int recvaddrlen,

char *message)

{

return overlay_mdp_reply_error(sock,recvaddr,recvaddrlen,0,message);

}

int overlay_mdp_releasebindings(struct sockaddr_un *recvaddr,int recvaddrlen)

{

/* Free up any MDP bindings held by this client. */

int i;

for(i=0;i<MDP_MAX_BINDINGS;i++)

if (mdp_bindings[i].name_len==recvaddrlen)

if (!memcmp(mdp_bindings[i].socket_name,recvaddr->sun_path,recvaddrlen))

mdp_bindings[i].port=0;

return 0;

}

int overlay_mdp_process_bind_request(int sock, struct subscriber *subscriber, int port,

int flags, struct sockaddr_un *recvaddr, int recvaddrlen)

{

int i;

if (port<=0){

return WHYF("Port %d cannot be bound", port);

}

if (!mdp_bindings_initialised) {

/* Mark all slots as unused */

for(i=0;i<MDP_MAX_BINDINGS;i++)

mdp_bindings[i].port=0;

mdp_bindings_initialised=1;

}

/* See if binding already exists */

int free=-1;

for(i=0;i<MDP_MAX_BINDINGS;i++) {

/* Look for duplicate bindings */

if (mdp_bindings[i].port == port && mdp_bindings[i].subscriber == subscriber) {

if (mdp_bindings[i].name_len==recvaddrlen &&

!memcmp(mdp_bindings[i].socket_name,recvaddr->sun_path,recvaddrlen)) {

// this client already owns this port binding?

INFO("Identical binding exists");

return 0;

}else if(flags&MDP_FORCE){

// steal the port binding

free=i;

break;

}else{

return WHY("Port already in use");

}

}

/* Look for free slots in case we need one */

if ((free==-1)&&(mdp_bindings[i].port==0)) free=i;

}

/* Okay, so no binding exists. Make one, and return success.

If we have too many bindings, we should return an error.

XXX - We don't find out when the socket responsible for a binding has died,

so stale bindings can hang around. We really need a solution to this, e.g.,

probing the sockets periodically (by sending an MDP NOOP frame perhaps?) and

destroying any socket that reports an error.

*/

if (free==-1) {

/* XXX Should we probe for stale bindings here and now, since this is when

we want the spare slots ?

Picking one at random is as good a policy as any.

Call listeners don't have a port binding, so are unaffected by this.

*/

free=random()%MDP_MAX_BINDINGS;

}

if (debug & DEBUG_MDPREQUESTS)

DEBUGF("Binding %s:%d",alloca_tohex_sid(subscriber->sid),port);

/* Okay, record binding and report success */

mdp_bindings[free].port=port;

mdp_bindings[free].subscriber=subscriber;

mdp_bindings[free].name_len=recvaddrlen-2;

memcpy(mdp_bindings[free].socket_name,recvaddr->sun_path,

mdp_bindings[free].name_len);

mdp_bindings[free].binding_time=gettime_ms();

return 0;

}

int overlay_mdp_decrypt(struct overlay_frame *f, overlay_mdp_frame *mdp)

{

IN();

int len=f->payload->sizeLimit - f->payload->position;

unsigned char *b = NULL;

unsigned char plain_block[len+16];

/* Indicate MDP message type */

mdp->packetTypeAndFlags=MDP_TX;

switch(f->modifiers&OF_CRYPTO_BITS) {

case 0:

/* get payload */

b=&f->payload->bytes[f->payload->position];

mdp->packetTypeAndFlags|=MDP_NOCRYPT|MDP_NOSIGN;

break;

case OF_CRYPTO_CIPHERED:

RETURN(WHY("decryption not implemented"));

case OF_CRYPTO_SIGNED:

{

/* This call below will dispatch the request for the SAS if we don't

already have it. In the meantime, we just drop the frame if the SAS

is not available. */

if (!f->source->sas_valid){

keyring_send_sas_request(f->source);

RETURN(WHY("SAS key not currently on record, cannot verify"));

}

/* get payload and following compacted signature */

b=&f->payload->bytes[f->payload->position];

len=f->payload->sizeLimit - f->payload->position - crypto_sign_edwards25519sha512batch_BYTES;

/* reconstitute signature by putting hash between two halves of signature */

unsigned char signature[crypto_hash_sha512_BYTES

+crypto_sign_edwards25519sha512batch_BYTES];

bcopy(&b[len],&signature[0],32);

crypto_hash_sha512(&signature[32],b,len);

if (0) dump("hash for verification",&signature[32],crypto_hash_sha512_BYTES);

bcopy(&b[len+32],&signature[32+crypto_hash_sha512_BYTES],32);

/* verify signature */

unsigned char m[crypto_hash_sha512_BYTES];

unsigned long long mlen=0;

int result

=crypto_sign_edwards25519sha512batch_open(m,&mlen,

signature,sizeof(signature),

f->source->sas_public);

if (result) {

WHY("Signature verification failed");

dump("data", b, len);

dump("signature", signature, sizeof(signature));

RETURN(-1);

} else if (0) DEBUG("signature check passed");

}

mdp->packetTypeAndFlags|=MDP_NOCRYPT;

break;

case OF_CRYPTO_CIPHERED|OF_CRYPTO_SIGNED:

{

if (0) DEBUGF("crypted MDP frame for %s", alloca_tohex_sid(mdp->out.dst.sid));

unsigned char *k=keyring_get_nm_bytes(&mdp->out.dst,&mdp->out.src);

unsigned char *nonce=&f->payload->bytes[f->payload->position];

int nb=crypto_box_curve25519xsalsa20poly1305_NONCEBYTES;

int zb=crypto_box_curve25519xsalsa20poly1305_ZEROBYTES;

if (!k)

RETURN(WHY("I don't have the private key required to decrypt that"));

bzero(&plain_block[0],crypto_box_curve25519xsalsa20poly1305_ZEROBYTES-16);

int cipher_len=f->payload->sizeLimit - f->payload->position - nb;

bcopy(&f->payload->bytes[nb + f->payload->position],&plain_block[16],cipher_len);

if (0) {

dump("nm bytes",k,crypto_box_curve25519xsalsa20poly1305_BEFORENMBYTES);

dump("nonce",nonce,crypto_box_curve25519xsalsa20poly1305_NONCEBYTES);

dump("cipher block",&plain_block[16],cipher_len);

}

if (crypto_box_curve25519xsalsa20poly1305_open_afternm

(plain_block,plain_block,cipher_len+16,nonce,k)) {

RETURN(WHYF("crypto_box_open_afternm() failed (forged or corrupted packet of %d bytes)",cipher_len+16));

}

if (0) dump("plain block",&plain_block[zb],cipher_len-16);

b=&plain_block[zb];

len=cipher_len-16;

break;

}

}

if (!b)

RETURN(WHY("Failed to decode mdp payload"));

int version=(b[0]<<8)+b[1];

if (version!=0x0101) RETURN(WHY("Saw unsupported MDP frame version"));

/* extract MDP port numbers */

mdp->in.src.port=(b[2]<<24)+(b[3]<<16)+(b[4]<<8)+b[5];

mdp->in.dst.port=(b[6]<<24)+(b[7]<<16)+(b[8]<<8)+b[9];

if (0) DEBUGF("RX mdp dst.port=%d, src.port=%d", mdp->in.dst.port, mdp->in.src.port);

mdp->in.payload_length=len-10;

bcopy(&b[10],&mdp->in.payload[0],mdp->in.payload_length);

RETURN(0);

}

int overlay_saw_mdp_containing_frame(struct overlay_frame *f, time_ms_t now)

{

IN();

/* Take frame source and destination and use them to populate mdp->in->{src,dst}

SIDs.

Take ports from mdp frame itself.

Take payload from mdp frame itself.

*/

overlay_mdp_frame mdp;

bzero(&mdp, sizeof(overlay_mdp_frame));

/* Get source and destination addresses */

if (f->destination)

bcopy(f->destination->sid,mdp.in.dst.sid,SID_SIZE);

else{

// pack the broadcast address into the mdp structure

memset(mdp.in.dst.sid, 0xFF, SID_SIZE - BROADCAST_LEN);

bcopy(f->broadcast_id.id, mdp.in.dst.sid + SID_SIZE - BROADCAST_LEN, BROADCAST_LEN);

}

bcopy(f->source->sid,mdp.in.src.sid,SID_SIZE);

/* copy crypto flags from frame so that we know if we need to decrypt or verify it */

if (overlay_mdp_decrypt(f,&mdp))

RETURN(-1);

/* and do something with it! */

RETURN(overlay_saw_mdp_frame(&mdp,now));

}

int overlay_mdp_swap_src_dst(overlay_mdp_frame *mdp)

{

sockaddr_mdp temp;

bcopy(&mdp->out.dst,&temp,sizeof(sockaddr_mdp));

bcopy(&mdp->out.src,&mdp->out.dst,sizeof(sockaddr_mdp));

bcopy(&temp,&mdp->out.src,sizeof(sockaddr_mdp));

return 0;

}

int overlay_saw_mdp_frame(overlay_mdp_frame *mdp, time_ms_t now)

{

IN();

int i;

int match=-1;

switch(mdp->packetTypeAndFlags&MDP_TYPE_MASK) {

case MDP_TX:

/* Regular MDP frame addressed to us. Look for matching port binding,

and if available, push to client. Else do nothing, or if we feel nice

send back a connection refused type message? Silence is probably the

more prudent path.

*/

if (debug & DEBUG_MDPREQUESTS)

DEBUGF("Received packet with listener (MDP ports: src=%s*:%d, dst=%d)",

alloca_tohex(mdp->out.src.sid, 7),

mdp->out.src.port,mdp->out.dst.port);

// TODO pass in dest subscriber as an argument, we should know it by now

struct subscriber *destination = NULL;

if (!is_broadcast(mdp->out.dst.sid)){

destination = find_subscriber(mdp->out.dst.sid, SID_SIZE, 1);

}

for(i=0;i<MDP_MAX_BINDINGS;i++)

{

if (mdp_bindings[i].port!=mdp->out.dst.port)

continue;

if ((!destination) || mdp_bindings[i].subscriber == destination){

/* exact match, so stop searching */

match=i;

break;

}else if (!mdp_bindings[i].subscriber){

/* If we find an "ANY" binding, remember it. But we will prefer an exact match if we find one */

match=i;

}

}

if (match>-1) {

struct sockaddr_un addr;

bcopy(mdp_bindings[match].socket_name,addr.sun_path,mdp_bindings[match].name_len);

addr.sun_family=AF_UNIX;

errno=0;

int len=overlay_mdp_relevant_bytes(mdp);

int r=sendto(mdp_named.poll.fd,mdp,len,0,(struct sockaddr*)&addr,sizeof(addr));

if (r==overlay_mdp_relevant_bytes(mdp)) {

RETURN(0);

}

WHY("didn't send mdp packet");

if (errno==ENOENT) {

/* far-end of socket has died, so drop binding */

INFOF("Closing dead MDP client '%s'",mdp_bindings[match].socket_name);

overlay_mdp_releasebindings(&addr,mdp_bindings[match].name_len);

}

WHY_perror("sendto(e)");

RETURN(WHY("Failed to pass received MDP frame to client"));

} else {

/* No socket is bound, ignore the packet ... except for magic sockets */

switch(mdp->out.dst.port) {

case MDP_PORT_VOMP:

RETURN(vomp_mdp_received(mdp));

case MDP_PORT_KEYMAPREQUEST:

/* Either respond with the appropriate SAS, or record this one if it

verifies out okay. */

if (debug & DEBUG_MDPREQUESTS)

DEBUG("MDP_PORT_KEYMAPREQUEST");

RETURN(keyring_mapping_request(keyring,mdp));

case MDP_PORT_DNALOOKUP: /* attempt to resolve DID to SID */

{

int cn=0,in=0,kp=0;

char did[64+1];

int pll=mdp->out.payload_length;

if (pll>64) pll=64;

/* get did from the packet */

if (mdp->out.payload_length<1) {

RETURN(WHY("Empty DID in DNA resolution request")); }

bcopy(&mdp->out.payload[0],&did[0],pll);

did[pll]=0;

if (debug & DEBUG_MDPREQUESTS)

DEBUG("MDP_PORT_DNALOOKUP");

int results=0;

while(keyring_find_did(keyring,&cn,&in,&kp,did))

{

/* package DID and Name into reply (we include the DID because

it could be a wild-card DID search, but the SID is implied

in the source address of our reply). */

if (keyring->contexts[cn]->identities[in]->keypairs[kp]->private_key_len > DID_MAXSIZE)

/* skip excessively long DID records */

continue;

const unsigned char *packedSid = keyring->contexts[cn]->identities[in]->keypairs[0]->public_key;

const char *unpackedDid = (const char *) keyring->contexts[cn]->identities[in]->keypairs[kp]->private_key;

const char *name = (const char *)keyring->contexts[cn]->identities[in]->keypairs[kp]->public_key;

// URI is sid://SIDHEX/DID

strbuf b = strbuf_alloca(SID_STRLEN + DID_MAXSIZE + 10);

strbuf_puts(b, "sid://");

strbuf_tohex(b, packedSid, SID_SIZE);

strbuf_puts(b, "/local/");

strbuf_puts(b, unpackedDid);

overlay_mdp_dnalookup_reply(&mdp->out.src, packedSid, strbuf_str(b), unpackedDid, name);

kp++;

results++;

}

if (!results) {

/* No local results, so see if servald has been configured to use

a DNA-helper that can provide additional mappings. This provides

a generalised interface for resolving telephone numbers into URIs.

The first use will be for resolving DIDs to SIP addresses for

OpenBTS boxes run by the OTI/Commotion project.

The helper is run asynchronously, and the replies will be delivered

when results become available, so this function will return

immediately, so as not to cause blockages and delays in servald.

*/

dna_helper_enqueue(mdp, did, mdp->out.src.sid);

monitor_tell_formatted(MONITOR_DNAHELPER, "LOOKUP:%s:%d:%s\n", alloca_tohex_sid(mdp->out.src.sid), mdp->out.src.port, did);

}

RETURN(0);

}

break;

case MDP_PORT_ECHO: /* well known ECHO port for TCP/UDP and now MDP */

{

/* Echo is easy: we swap the sender and receiver addresses (and thus port

numbers) and send the frame back. */

/* Swap addresses */

overlay_mdp_swap_src_dst(mdp);

/* Prevent echo:echo connections and the resulting denial of service from triggering endless pongs. */

if (mdp->out.dst.port==MDP_PORT_ECHO) {

RETURN(WHY("echo loop averted"));

}

/* If the packet was sent to broadcast, then replace broadcast address

with our local address. For now just responds with first local address */

if (is_broadcast(mdp->out.src.sid))

{

if (my_subscriber)

bcopy(my_subscriber->sid,

mdp->out.src.sid,SID_SIZE);

else

/* No local addresses, so put all zeroes */

bzero(mdp->out.src.sid,SID_SIZE);

}

/* queue frame for delivery */

overlay_mdp_dispatch(mdp,0 /* system generated */,

NULL,0);

/* and switch addresses back around in case the caller was planning on

using MDP structure again (this happens if there is a loop-back reply

and the frame needs sending on, as happens with broadcasts. MDP ping

is a simple application where this occurs). */

overlay_mdp_swap_src_dst(mdp);

}

break;

default:

/* Unbound socket. We won't be sending ICMP style connection refused

messages, partly because they are a waste of bandwidth. */

RETURN(WHYF("Received packet for which no listening process exists (MDP ports: src=%d, dst=%d",

mdp->out.src.port,mdp->out.dst.port));

}

}

break;

default:

RETURN(WHYF("We should only see MDP_TX frames here (MDP message type = 0x%x)",

mdp->packetTypeAndFlags));

}

RETURN(0);

}

int overlay_mdp_dnalookup_reply(const sockaddr_mdp *dstaddr, const unsigned char *resolved_sid, const char *uri, const char *did, const char *name)

{

overlay_mdp_frame mdpreply;

bzero(&mdpreply, sizeof mdpreply);

mdpreply.packetTypeAndFlags = MDP_TX; // outgoing MDP message

memcpy(mdpreply.out.src.sid, resolved_sid, SID_SIZE);

mdpreply.out.src.port = MDP_PORT_DNALOOKUP;

bcopy(dstaddr, &mdpreply.out.dst, sizeof(sockaddr_mdp));

/* build reply as TOKEN|URI|DID|NAME|<NUL> */

strbuf b = strbuf_local((char *)mdpreply.out.payload, sizeof mdpreply.out.payload);

strbuf_tohex(b, resolved_sid, SID_SIZE);

strbuf_sprintf(b, "|%s|%s|%s|", uri, did, name);

if (strbuf_overrun(b))

return WHY("MDP payload overrun");

mdpreply.out.payload_length = strbuf_len(b) + 1;

/* deliver reply */

return overlay_mdp_dispatch(&mdpreply, 0 /* system generated */, NULL, 0);

}

int overlay_mdp_check_binding(struct subscriber *subscriber, int port, int userGeneratedFrameP,

struct sockaddr_un *recvaddr, int recvaddrlen)

{

/* Check if the address is in the list of bound addresses,

and that the recvaddr matches. */

int i;

for(i = 0; i < MDP_MAX_BINDINGS; ++i) {

if (mdp_bindings[i].port != port)

continue;

if ((!mdp_bindings[i].subscriber) || mdp_bindings[i].subscriber == subscriber) {

/* Binding matches, now make sure the sockets match */

if ( mdp_bindings[i].name_len == recvaddrlen - sizeof(short)

&& memcmp(mdp_bindings[i].socket_name, recvaddr->sun_path, recvaddrlen - sizeof(short)) == 0

) {

/* Everything matches, so this unix socket and MDP address combination is valid */

return 0;

}

}

}

/* Check for build-in port listeners */

if (!userGeneratedFrameP){

switch(port) {

case MDP_PORT_NOREPLY:

case MDP_PORT_ECHO:

case MDP_PORT_KEYMAPREQUEST:

case MDP_PORT_VOMP:

case MDP_PORT_DNALOOKUP:

return 0;

}

}

return WHYF("No such binding: recvaddr=%p %s addr=%s port=%u (0x%x) -- possible spoofing attack",

recvaddr,

recvaddr ? alloca_toprint(-1, recvaddr->sun_path, recvaddrlen - sizeof(short)) : "",

alloca_tohex_sid(subscriber->sid),

port, port

);

}

/* Construct MDP packet frame from overlay_mdp_frame structure

(need to add return address from bindings list, and copy

payload etc).

This is for use by the SERVER.

Clients should use overlay_mdp_send()

*/

int overlay_mdp_dispatch(overlay_mdp_frame *mdp,int userGeneratedFrameP,

struct sockaddr_un *recvaddr,int recvaddrlen)

{

IN();

/* Prepare the overlay frame for dispatch */

struct overlay_frame *frame = calloc(1,sizeof(struct overlay_frame));

if (!frame)

FATAL("Couldn't allocate frame buffer");

if (is_sid_any(mdp->out.src.sid)){

/* set source to ourselves */

frame->source = my_subscriber;

bcopy(frame->source->sid, mdp->out.src.sid, SID_SIZE);

}else if (is_broadcast(mdp->out.src.sid)){

/* This is rather naughty if it happens, since broadcasting a

response can lead to all manner of nasty things.

Picture a packet with broadcast as the source address, sent

to, say, the MDP echo port on another node, and with a source

port also of the echo port. Said echo will get multiplied many,

many, many times over before the TTL finally reaches zero.

So we just say no to any packet with a broadcast source address.

(Of course we have other layers of protection against such

shenanigens, such as using BPIs to smart-flood broadcasts, but

security comes through depth.)

*/

op_free(frame);

RETURN(WHY("Packet had broadcast address as source address"));

}else{

// assume all local identities have already been unlocked and marked as SELF.

frame->source = find_subscriber(mdp->out.src.sid, SID_SIZE, 0);

if (!frame->source){

op_free(frame);

RETURN(WHYF("Possible spoofing attempt, tried to send a packet from %s, which is an unknown SID", alloca_tohex_sid(mdp->out.src.sid)));

}

if (frame->source->reachable!=REACHABLE_SELF){

op_free(frame);

RETURN(WHYF("Possible spoofing attempt, tried to send a packet from %s", alloca_tohex_sid(mdp->out.src.sid)));

}

}

/* Work out if destination is broadcast or not */

if (overlay_mdp_check_binding(frame->source, mdp->out.src.port, userGeneratedFrameP,

recvaddr, recvaddrlen)){

op_free(frame);

RETURN(overlay_mdp_reply_error

(mdp_named.poll.fd,

(struct sockaddr_un *)recvaddr,

recvaddrlen,8,

"Source address is invalid (you must bind to a source address before"

" you can send packets"));

}

if (is_broadcast(mdp->out.dst.sid)){

/* broadcast packets cannot be encrypted, so complain if MDP_NOCRYPT

flag is not set. Also, MDP_NOSIGN must also be applied, until

NaCl cryptobox keys can be used for signing. */

if (!(mdp->packetTypeAndFlags&MDP_NOCRYPT)){

op_free(frame);

RETURN(overlay_mdp_reply_error(mdp_named.poll.fd,

recvaddr,recvaddrlen,5,

"Broadcast packets cannot be encrypted "));

}

overlay_broadcast_generate_address(&frame->broadcast_id);

frame->destination = NULL;

}else{

frame->destination = find_subscriber(mdp->out.dst.sid, SID_SIZE, 1);

}

frame->ttl=64; /* normal TTL (XXX allow setting this would be a good idea) */

if (!frame->destination || frame->destination->reachable == REACHABLE_SELF)

{

/* Packet is addressed such that we should process it. */

overlay_saw_mdp_frame(mdp,gettime_ms());

if (frame->destination) {

/* Is local, and is not broadcast, so shouldn't get sent out

on the wire. */

op_free(frame);

RETURN(0);

}

}

/* give voice packets priority */

if (mdp->out.dst.port==MDP_PORT_VOMP) frame->type=OF_TYPE_DATA_VOICE;

else frame->type=OF_TYPE_DATA;

frame->prev=NULL;

frame->next=NULL;

frame->payload=ob_new();

int fe=0;

/* Work out the disposition of the frame-> For now we are only worried

about the crypto matters, and not compression that may be applied

before encryption (since applying it after is useless as ciphered

text should have maximum entropy). */

switch(mdp->packetTypeAndFlags&(MDP_NOCRYPT|MDP_NOSIGN)) {

case 0: /* crypted and signed (using CryptoBox authcryption primitive) */

frame->modifiers=OF_CRYPTO_SIGNED|OF_CRYPTO_CIPHERED;

/* Prepare payload */

ob_makespace(frame->payload,

1 // frame type (MDP)

+1 // MDP version

+4 // dst port

+4 // src port

+crypto_box_curve25519xsalsa20poly1305_NONCEBYTES

+crypto_box_curve25519xsalsa20poly1305_ZEROBYTES

+mdp->out.payload_length);

{

/* write cryptobox nonce */

unsigned char nonce[crypto_box_curve25519xsalsa20poly1305_NONCEBYTES];

if (urandombytes(nonce,crypto_box_curve25519xsalsa20poly1305_NONCEBYTES)) {

op_free(frame);

RETURN(WHY("urandombytes() failed to generate nonce"));

}

fe|= ob_append_bytes(frame->payload,nonce,crypto_box_curve25519xsalsa20poly1305_NONCEBYTES);

/* generate plain message with zero bytes and get ready to cipher it */

unsigned char plain[crypto_box_curve25519xsalsa20poly1305_ZEROBYTES

+10+mdp->out.payload_length];

/* zero bytes */

int zb=crypto_box_curve25519xsalsa20poly1305_ZEROBYTES;

bzero(&plain[0],zb);

/* MDP version 1 */

plain[zb+0]=0x01;

plain[zb+1]=0x01;

/* Ports */

plain[zb+2]=(mdp->out.src.port>>24)&0xff;

plain[zb+3]=(mdp->out.src.port>>16)&0xff;

plain[zb+4]=(mdp->out.src.port>>8)&0xff;

plain[zb+5]=(mdp->out.src.port>>0)&0xff;

plain[zb+6]=(mdp->out.dst.port>>24)&0xff;

plain[zb+7]=(mdp->out.dst.port>>16)&0xff;

plain[zb+8]=(mdp->out.dst.port>>8)&0xff;

plain[zb+9]=(mdp->out.dst.port>>0)&0xff;

/* payload */

bcopy(&mdp->out.payload,&plain[zb+10],mdp->out.payload_length);

int cipher_len=zb+10+mdp->out.payload_length;

/* get pre-computed PKxSK bytes (the slow part of auth-cryption that can be

retained and reused, and use that to do the encryption quickly. */

unsigned char *k=keyring_get_nm_bytes(&mdp->out.src,&mdp->out.dst);

if (!k) {

op_free(frame);

RETURN(WHY("could not compute Curve25519(NxM)"));

}

/* Get pointer to place in frame where the ciphered text needs to go */

int cipher_offset=frame->payload->position;

unsigned char *cipher_text=ob_append_space(frame->payload,cipher_len);

if (fe||(!cipher_text)){

op_free(frame);

RETURN(WHY("could not make space for ciphered text"));

}

/* Actually authcrypt the payload */

if (crypto_box_curve25519xsalsa20poly1305_afternm

(cipher_text,plain,cipher_len,nonce,k)){

op_free(frame);

RETURN(WHY("crypto_box_afternm() failed"));

}

/* now shuffle down 16 bytes to get rid of the temporary space that crypto_box

uses. */

bcopy(&cipher_text[16],&cipher_text[0],cipher_len-16);

frame->payload->position-=16;

if (0) {

DEBUG("authcrypted mdp frame");

dump("nm bytes",k,crypto_box_curve25519xsalsa20poly1305_BEFORENMBYTES);

dump("nonce",nonce,crypto_box_curve25519xsalsa20poly1305_NONCEBYTES);

dump("plain text",&plain[16],cipher_len-16);

dump("cipher text",cipher_text,cipher_len-16);

DEBUGF("frame->payload->length=%d,cipher_len-16=%d,cipher_offset=%d", frame->payload->position,cipher_len-16,cipher_offset);

dump("frame",&frame->payload->bytes[0],

frame->payload->position);

}

}

break;

case MDP_NOCRYPT:

/* Payload is sent unencrypted, but signed.

To save space we do a trick where we hash the payload, and get the

signature of that, but do not send the hash itself, since that can

be reproduced (and indeed must be for verification) at the receiver's

end.

As the signing key is implicit, and the hash is also implicit, we can

chop out part of the signature and thus save some bytes.

*/

frame->modifiers=OF_CRYPTO_SIGNED;

/* Prepare payload */

ob_makespace(frame->payload,

1 // frame type (MDP)

+1 // MDP version

+4 // dst port

+4 // src port

+crypto_sign_edwards25519sha512batch_BYTES

+mdp->out.payload_length);

{

unsigned char *key=keyring_find_sas_private(keyring, frame->source->sid, NULL);

if (!key) {

op_free(frame);

RETURN(WHY("could not find signing key"));

}

/* Build plain-text that includes header and hash it so that

we can sign that hash. */

unsigned char hash[crypto_hash_sha512_BYTES];

int plain_len = 10+mdp->out.payload_length;

unsigned char *plain = frame->payload->bytes + frame->payload->position;

if (!plain)

return WHY("Unable to allocate space for payload and signature");

/* MDP version 1 */

ob_append_byte(frame->payload,0x01);

ob_append_byte(frame->payload,0x01);

/* Destination port */

ob_append_ui32(frame->payload,mdp->out.src.port);

ob_append_ui32(frame->payload,mdp->out.dst.port);

ob_append_bytes(frame->payload,mdp->out.payload,mdp->out.payload_length);

/* now hash it */

crypto_hash_sha512(hash,plain,plain_len);

unsigned char signature[crypto_hash_sha512_BYTES

+crypto_sign_edwards25519sha512batch_BYTES];

unsigned long long sig_len=0;

crypto_sign_edwards25519sha512batch(signature,&sig_len,

hash,crypto_hash_sha512_BYTES,

key);

if (!sig_len) {

op_free(frame);

RETURN(WHY("Signing MDP frame failed"));

}

if (0){

dump("payload", plain, plain_len);

dump("signature", signature, sizeof(signature));

}

/* chop hash out of middle of signature since it has to be recomputed

at the far end, anyway, and ammend the two halves of the signature. */

ob_append_bytes(frame->payload,&signature[0],32);

ob_append_bytes(frame->payload,&signature[32+crypto_hash_sha512_BYTES],32);

}

break;

case MDP_NOSIGN|MDP_NOCRYPT: /* clear text and no signature */

frame->modifiers=0;

/* Copy payload body in */

ob_makespace(frame->payload,

1 // frame type (MDP)

+1 // MDP version

+4 // dst port

+4 // src port

+mdp->out.payload_length);

/* MDP version 1 */

ob_append_byte(frame->payload,0x01);

ob_append_byte(frame->payload,0x01);

/* Destination port */

ob_append_ui32(frame->payload,mdp->out.src.port);

ob_append_ui32(frame->payload,mdp->out.dst.port);

ob_append_bytes(frame->payload,mdp->out.payload,mdp->out.payload_length);

break;

case MDP_NOSIGN:

default:

/* ciphered, but not signed.

This means we don't use CryptoBox, but rather a more compact means

of representing the ciphered stream segment.

*/

op_free(frame);

RETURN(WHY("Not implemented"));

break;

}

// TODO include priority in packet header

int qn=OQ_ORDINARY;

/* Make sure voice traffic gets priority */

if ((frame->type&OF_TYPE_BITS)==OF_TYPE_DATA_VOICE) {

qn=OQ_ISOCHRONOUS_VOICE;

rhizome_saw_voice_traffic();

}

frame->send_copies = mdp->out.send_copies;

if (overlay_payload_enqueue(qn, frame))

op_free(frame);

RETURN(0);

}

struct search_state{

};

static int search_subscribers(struct subscriber *subscriber, void *context){

struct search_state *state = context;

if (state->mdp->addrlist.mode == MDP_ADDRLIST_MODE_SELF && subscriber->reachable != REACHABLE_SELF){

return 0;

}

if (state->mdp->addrlist.mode == MDP_ADDRLIST_MODE_ROUTABLE_PEERS &&

(subscriber->reachable != REACHABLE_DIRECT &&

subscriber->reachable != REACHABLE_INDIRECT &&

subscriber->reachable != REACHABLE_UNICAST)){

return 0;

}

if (state->mdp->addrlist.mode == MDP_ADDRLIST_MODE_ALL_PEERS &&

subscriber->reachable == REACHABLE_SELF){

return 0;

}

if (state->count++ >= state->first && state->index < state->max) {

memcpy(state->mdpreply->addrlist.sids[state->index++], subscriber->sid, SID_SIZE);

}

return 0;

}

void overlay_mdp_poll(struct sched_ent *alarm)

{

if (alarm->poll.revents & POLLIN) {

unsigned char buffer[16384];

int ttl;

unsigned char recvaddrbuffer[1024];

struct sockaddr *recvaddr=(struct sockaddr *)&recvaddrbuffer[0];

socklen_t recvaddrlen=sizeof(recvaddrbuffer);

struct sockaddr_un *recvaddr_un=NULL;

ttl=-1;

bzero((void *)recvaddrbuffer,sizeof(recvaddrbuffer));

ssize_t len = recvwithttl(alarm->poll.fd,buffer,sizeof(buffer),&ttl, recvaddr, &recvaddrlen);

recvaddr_un=(struct sockaddr_un *)recvaddr;

if (len>0) {

/* Look at overlay_mdp_frame we have received */

overlay_mdp_frame *mdp=(overlay_mdp_frame *)&buffer[0];

unsigned int mdp_type = mdp->packetTypeAndFlags & MDP_TYPE_MASK;

switch (mdp_type) {

case MDP_GOODBYE:

if (debug & DEBUG_MDPREQUESTS) DEBUG("MDP_GOODBYE");

overlay_mdp_releasebindings(recvaddr_un,recvaddrlen);

return;

case MDP_NODEINFO:

if (debug & DEBUG_MDPREQUESTS) DEBUG("MDP_NODEINFO");

overlay_route_node_info(mdp,recvaddr_un,recvaddrlen);