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Support multiple UDP clients with connection tracking.

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If an incoming UDP packet shares the same host and source port as
an existing connection, we consider it part of the input stream.
This commit is contained in:
Sam Hocevar 2017-09-07 16:29:23 +02:00
parent b5206eab4e
commit 6bb27c18a6
2 changed files with 47 additions and 22 deletions
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67
rinetd.c
View File

@ -338,7 +338,8 @@ static void setConnectionCount(int newCount)
closesocket(coInfo[i].local.fd);
}
if (coInfo[i].remote.fd != INVALID_SOCKET) {
closesocket(coInfo[i].remote.fd);
if (coInfo[i].remote.proto == protoTcp)
closesocket(coInfo[i].remote.fd);
}
free(coInfo[i].local.buffer);
}
@ -453,8 +454,11 @@ static void selectPass(void)
for (int i = 0; i < coTotal; ++i) {
ConnectionInfo *cnx = &coInfo[i];
if (cnx->remote.fd != INVALID_SOCKET) {
if (FD_ISSET_EXT(cnx->remote.fd, readfds)) {
handleRead(cnx, &cnx->remote, &cnx->local);
/* Do not read on remote UDP sockets, the server does it. */
if (cnx->remote.proto != protoUdp) {
if (FD_ISSET_EXT(cnx->remote.fd, readfds)) {
handleRead(cnx, &cnx->remote, &cnx->local);
}
}
}
if (cnx->remote.fd != INVALID_SOCKET) {
@ -513,7 +517,8 @@ static void handleWrite(ConnectionInfo *cnx, Socket *socket, Socket *other_socke
if (cnx->coClosing && (socket->sentPos == other_socket->recvPos)) {
PERROR("rinetd: local closed and no more output");
logEvent(cnx, cnx->server, cnx->coLog);
closesocket(socket->fd);
if (socket->proto == protoTcp)
closesocket(socket->fd);
socket->fd = INVALID_SOCKET;
return;
}
@ -564,18 +569,12 @@ static void handleClose(ConnectionInfo *cnx, Socket *socket, Socket *other_socke
static void handleAccept(ServerInfo const *srv)
{
ConnectionInfo *cnx = findAvailableConnection();
if (!cnx) {
return;
}
struct sockaddr addr;
SOCKLEN_T addrlen = sizeof(addr);
SOCKET nfd;
/* Get remote address using accept() in TCP mode, recvfrom()
in UDP mode. */
if (srv->fromProto == protoTcp) {
/* In TCP mode, get remote address using accept(). */
nfd = accept(srv->fd, &addr, &addrlen);
if (nfd == INVALID_SOCKET) {
syslog(LOG_ERR, "accept(%d): %m\n", srv->fd);
@ -590,14 +589,39 @@ static void handleAccept(ServerInfo const *srv)
setsockopt(nfd, SOL_SOCKET, SO_LINGER, &tmp, sizeof(tmp));
#endif
} else /* if (srv->fromProto == protoUdp) */ {
/* In UDP mode, get remote address using recvfrom() and check
for an existing connection from this client. */
nfd = srv->fd;
ssize_t ret = recvfrom(srv->fd, NULL, 0, MSG_PEEK,
&addr, &addrlen);
if (ret < 0) {
if (GetLastError() == WSAEWOULDBLOCK) {
return;
}
if (GetLastError() == WSAEINPROGRESS) {
return;
}
syslog(LOG_ERR, "recvfrom(%d): %m\n", srv->fd);
logEvent(NULL, srv, logAcceptFailed);
return;
}
for (int i = 0; i < coTotal; ++i) {
ConnectionInfo *cnx = &coInfo[i];
struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
if (cnx->remote.fd == nfd
&& cnx->remoteAddress.sin_family == addr_in->sin_family
&& cnx->remoteAddress.sin_port == addr_in->sin_port
&& cnx->remoteAddress.sin_addr.s_addr == addr_in->sin_addr.s_addr) {
handleRead(cnx, &cnx->remote, &cnx->local);
return;
}
}
}
ConnectionInfo *cnx = findAvailableConnection();
if (!cnx) {
return;
}
cnx->local.fd = INVALID_SOCKET;
@ -608,7 +632,7 @@ static void handleAccept(ServerInfo const *srv)
cnx->remote.proto = srv->fromProto;
cnx->remote.recvPos = cnx->remote.sentPos = 0;
cnx->remote.recvBytes = cnx->remote.sentBytes = 0;
cnx->reAddresses.s_addr = ((struct sockaddr_in *)&addr)->sin_addr.s_addr;
cnx->remoteAddress = *(struct sockaddr_in *)&addr;
cnx->coClosing = 0;
cnx->coLog = logUnknownError;
cnx->server = srv;
@ -617,7 +641,8 @@ static void handleAccept(ServerInfo const *srv)
if (logCode != logAllowed) {
/* Local fd is not open yet, so only
close the remote socket. */
closesocket(cnx->remote.fd);
if (cnx->remote.proto == protoTcp)
closesocket(cnx->remote.fd);
cnx->remote.fd = INVALID_SOCKET;
logEvent(cnx, cnx->server, logCode);
return;
@ -632,7 +657,8 @@ static void handleAccept(ServerInfo const *srv)
: socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (cnx->local.fd == INVALID_SOCKET) {
syslog(LOG_ERR, "socket(): %m\n");
closesocket(cnx->remote.fd);
if (cnx->remote.proto == protoTcp)
closesocket(cnx->remote.fd);
cnx->remote.fd = INVALID_SOCKET;
logEvent(cnx, srv, logLocalSocketFailed);
return;
@ -645,7 +671,8 @@ static void handleAccept(ServerInfo const *srv)
saddr.sin_addr.s_addr = 0;
if (bind(cnx->local.fd, (struct sockaddr *) &saddr, sizeof(saddr)) == SOCKET_ERROR) {
closesocket(cnx->local.fd);
closesocket(cnx->remote.fd);
if (cnx->remote.proto == protoTcp)
closesocket(cnx->remote.fd);
cnx->remote.fd = INVALID_SOCKET;
cnx->local.fd = INVALID_SOCKET;
logEvent(cnx, srv, logLocalBindFailed);
@ -677,7 +704,8 @@ static void handleAccept(ServerInfo const *srv)
{
PERROR("rinetd: connect");
closesocket(cnx->local.fd);
closesocket(cnx->remote.fd);
if (cnx->remote.proto == protoTcp)
closesocket(cnx->remote.fd);
cnx->remote.fd = INVALID_SOCKET;
cnx->local.fd = INVALID_SOCKET;
logEvent(cnx, srv, logLocalConnectFailed);
@ -700,9 +728,7 @@ static void handleAccept(ServerInfo const *srv)
static int checkConnectionAllowed(ConnectionInfo const *cnx)
{
ServerInfo const *srv = cnx->server;
struct in_addr address;
address.s_addr = cnx->reAddresses.s_addr;
char const *addressText = inet_ntoa(address);
char const *addressText = inet_ntoa(cnx->remoteAddress.sin_addr);
/* 1. Check global allow rules. If there are no
global allow rules, it's presumed OK at
@ -890,8 +916,7 @@ static void logEvent(ConnectionInfo const *cnx, ServerInfo const *srv, int resul
int bytesOutput = 0;
int bytesInput = 0;
if (cnx != NULL) {
struct in_addr const *reAddress = &cnx->reAddresses;
addressText = inet_ntoa(*reAddress);
addressText = inet_ntoa(cnx->remoteAddress.sin_addr);
bytesOutput = cnx->remote.sentBytes;
bytesInput = cnx->remote.recvBytes;
}

2
types.h
View File

@ -58,7 +58,7 @@ typedef struct _connection_info ConnectionInfo;
struct _connection_info
{
Socket remote, local;
struct in_addr reAddresses;
struct sockaddr_in remoteAddress;
int coClosing;
int coLog;
ServerInfo const *server; // only useful for logEvent