/*----- Data structures ---------------------------------------------------*/
-struct listen {
- const struct addrops *ao;
- sel_file f;
-};
-
+/* A write buffer is the gadget which keeps track of our output and writes
+ * portions of it out as and when connections are ready for it.
+ */
#define WRBUFSZ 1024
struct writebuf {
- size_t o, n;
- sel_file wr;
- void (*func)(int, void *);
- void *p;
- unsigned char buf[WRBUFSZ];
+ size_t o; /* Offset of remaining data */
+ size_t n; /* Length of remaining data */
+ sel_file wr; /* Write selector */
+ void (*func)(int /*err*/, void *); /* Function to call on completion */
+ void *p; /* Context for `func' */
+ unsigned char buf[WRBUFSZ]; /* Output buffer */
};
-struct proxy {
- struct client *c;
- int fd;
- conn cn;
- selbuf b;
- struct writebuf wb;
- char nat[ADDRLEN];
+/* Structure for a listening socket. There's one of these for each address
+ * family we're looking after.
+ */
+struct listen {
+ const struct addrops *ao; /* Address family operations */
+ sel_file f; /* Watch for incoming connections */
};
+/* The main structure for a client. */
struct client {
- selbuf b;
- int fd;
- struct query q;
- struct listen *l;
- struct writebuf wb;
- struct proxy *px;
+ int fd; /* The connection to the client */
+ selbuf b; /* Accumulate lines of input */
+ union addr raddr; /* Remote address */
+ struct query q; /* The clients query and our reply */
+ struct sel_timer t; /* Timeout for idle or doomed conn */
+ struct listen *l; /* Back to the listener (and ops) */
+ struct writebuf wb; /* Write buffer for our reply */
+ struct proxy *px; /* Proxy if conn goes via NAT */
+ struct client *next; /* Next in a chain of clients */
+};
+
+/* A proxy connection. */
+struct proxy {
+ int fd; /* Connection; -1 if in progress */
+ struct client *c; /* Back to the client */
+ conn cn; /* Nonblocking connection */
+ selbuf b; /* Accumulate the response line */
+ struct writebuf wb; /* Write buffer for query */
+ char nat[ADDRLEN]; /* Server address, as text */
+ struct proxy *next; /* Next in a chain of proxies */
};
/*----- Static variables --------------------------------------------------*/
-static sel_state sel;
+static sel_state sel; /* I/O multiplexer state */
-static policy_v policy = DA_INIT;
-static fwatch polfw;
+static const char *pidfile = 0; /* Where to write daemon's pid */
-static unsigned char tokenbuf[4096];
-static size_t tokenptr = sizeof(tokenbuf);
-static int randfd;
+static const char *policyfile = POLICYFILE; /* Filename for global policy */
+static const struct policy default_policy = POLICY_INIT(A_NAME);
+static policy_v policy = DA_INIT; /* Vector of global policy rules */
+static fwatch polfw; /* Watch policy file for changes */
-/*----- Main code ---------------------------------------------------------*/
+static unsigned char tokenbuf[4096]; /* Random-ish data for tokens */
+static size_t tokenptr = sizeof(tokenbuf); /* Current read position */
-void logmsg(const struct query *q, int prio, const char *msg, ...)
+static struct client *dead_clients = 0; /* List of defunct clients */
+static struct proxy *dead_proxies = 0; /* List of defunct proxies */
+
+static unsigned flags = 0; /* Various interesting flags */
+#define F_SYSLOG 1u /* Use syslog for logging */
+#define F_RUNNING 2u /* Running properly now */
+
+/*----- Ident protocol parsing --------------------------------------------*/
+
+/* Advance *PP over whitespace characters. */
+static void skipws(const char **pp)
+ { while (isspace((unsigned char )**pp)) (*pp)++; }
+
+/* Copy a token of no more than N bytes starting at *PP into Q, advancing *PP
+ * over it.
+ */
+static int idtoken(const char **pp, char *q, size_t n)
{
- va_list ap;
- dstr d = DSTR_INIT;
+ const char *p = *pp;
- va_start(ap, msg);
- if (q) {
- dputsock(&d, q->ao, &q->s[L]);
- dstr_puts(&d, " <-> ");
- dputsock(&d, q->ao, &q->s[R]);
- dstr_puts(&d, ": ");
+ skipws(&p);
+ n--;
+ for (;;) {
+ if (*p == ':' || *p <= 32 || *p >= 127) break;
+ if (!n) return (-1);
+ *q++ = *p++;
+ n--;
}
- dstr_vputf(&d, msg, &ap);
- va_end(ap);
- fprintf(stderr, "yaid: %s\n", d.buf);
- dstr_destroy(&d);
+ *q++ = 0;
+ *pp = p;
+ return (0);
}
+/* Read an unsigned decimal number from *PP, and store it in *II. Check that
+ * it's between MIN and MAX, and advance *PP over it. Return zero for
+ * success, or nonzero if something goes wrong.
+ */
+static int unum(const char **pp, unsigned *ii, unsigned min, unsigned max)
+{
+ char *q;
+ unsigned long i;
+ int e;
+
+ skipws(pp);
+ if (!isdigit((unsigned char)**pp)) return (-1);
+ e = errno; errno = 0;
+ i = strtoul(*pp, &q, 10);
+ if (errno) return (-1);
+ *pp = q;
+ errno = e;
+ if (i < min || i > max) return (-1);
+ *ii = i;
+ return (0);
+}
+
+/*----- Asynchronous writing ----------------------------------------------*/
+
+/* Callback for actually writing stuff from a `writebuf'. */
static void write_out(int fd, unsigned mode, void *p)
{
ssize_t n;
struct writebuf *wb = p;
+ /* Try to write something. */
if ((n = write(fd, wb->buf + wb->o, wb->n)) < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) return;
wb->n = 0;
}
wb->o += n;
wb->n -= n;
+
+ /* If there's nothing left then restore the buffer to its empty state. */
if (!wb->n) {
wb->o = 0;
sel_rmfile(&wb->wr);
}
}
+/* Queue N bytes starting at P to be written. */
static int queue_write(struct writebuf *wb, const void *p, size_t n)
{
+ /* Maybe there's nothing to actually do. */
if (!n) return (0);
+
+ /* Make sure it'll fit. */
if (wb->n - wb->o + n > WRBUFSZ) return (-1);
+
+ /* If there's anything there already, then make sure it's at the start of
+ * the available space.
+ */
if (wb->o) {
memmove(wb->buf, wb->buf + wb->o, wb->n);
wb->o = 0;
}
- memcpy(wb->buf + wb->n, p, n);
+
+ /* If there's nothing currently there, then we're not requesting write
+ * notifications, so set that up, and force an initial wake-up.
+ */
if (!wb->n) {
sel_addfile(&wb->wr);
sel_force(&wb->wr);
}
+
+ /* Copy the new material over. */
+ memcpy(wb->buf + wb->n, p, n);
wb->n += n;
+
+ /* Done. */
return (0);
}
+/* Release resources allocated to WB. */
static void free_writebuf(struct writebuf *wb)
{ if (wb->n) sel_rmfile(&wb->wr); }
+/* Initialize a writebuf in *WB, writing to file descriptor FD. On
+ * completion, call FUNC, passing it P and an error indicator: either 0 for
+ * success or an `errno' value on failure.
+ */
static void init_writebuf(struct writebuf *wb,
int fd, void (*func)(int, void *), void *p)
{
wb->n = wb->o = 0;
}
-static void cancel_proxy(struct proxy *px)
+/*----- General utilities -------------------------------------------------*/
+
+static void vlogmsg(const struct query *q, int prio,
+ const char *msg, va_list *ap)
{
- if (px->fd == -1)
- conn_kill(&px->cn);
+ dstr d = DSTR_INIT;
+ time_t t;
+ struct tm *tm;
+ char buf[64];
+
+ if (q) {
+ dputsock(&d, q->ao, &q->s[L]);
+ dstr_puts(&d, " <-> ");
+ dputsock(&d, q->ao, &q->s[R]);
+ dstr_puts(&d, ": ");
+ }
+ dstr_vputf(&d, msg, ap);
+
+ if (!(flags & F_RUNNING))
+ moan("%s", d.buf);
+ else if (flags & F_SYSLOG)
+ syslog(prio, "%s", d.buf);
else {
- close(px->fd);
- selbuf_destroy(&px->b);
- free_writebuf(&px->wb);
+ t = time(0);
+ tm = localtime(&t);
+ strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S %z", tm);
+ fprintf(stderr, "%s %s: %s\n", buf, QUIS, d.buf);
}
- selbuf_enable(&px->c->b);
- px->c->px = 0;
- xfree(px);
+
+ dstr_destroy(&d);
}
-static void disconnect_client(struct client *c)
+/* Format and log MSG somewhere sensible, at the syslog(3) priority PRIO.
+ * Prefix it with a description of the query Q, if non-null.
+ */
+void logmsg(const struct query *q, int prio, const char *msg, ...)
{
- close(c->fd);
- selbuf_destroy(&c->b);
- free_writebuf(&c->wb);
- if (c->px) cancel_proxy(c->px);
- xfree(c);
+ va_list ap;
+
+ va_start(ap, msg);
+ vlogmsg(q, prio, msg, &ap);
+ va_end(ap);
+}
+
+/* Format and report MSG as a fatal error, and exit. */
+void fatal(const char *msg, ...)
+{
+ va_list ap;
+
+ va_start(ap, msg);
+ vlogmsg(0, LOG_CRIT, msg, &ap);
+ va_end(ap);
+ exit(1);
}
+/* Fix up a socket FD so that it won't bite us. Returns zero on success, or
+ * nonzero on error.
+ */
+static int fix_up_socket(int fd, const char *what)
+{
+ int yes = 1;
+
+ if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
+ logmsg(0, LOG_ERR, "failed to set %s connection nonblocking: %s",
+ what, strerror(errno));
+ return (-1);
+ }
+
+ if (setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, &yes, sizeof(yes))) {
+ logmsg(0, LOG_ERR,
+ "failed to disable `out-of-band' data on %s connection: %s",
+ what, strerror(errno));
+ return (-1);
+ }
+
+ return (0);
+}
+
+/*----- Client output functions -------------------------------------------*/
+
+static void disconnect_client(struct client *c);
+
+/* Notification that output has been written. If successful, re-enable the
+ * input buffer and prepare for another query.
+ */
static void done_client_write(int err, void *p)
{
struct client *c = p;
}
}
-static void write_to_client(struct client *c, const char *fmt, ...)
+/* Format the message FMT and queue it to be sent to the client. Client
+ * input will be disabled until the write completes.
+ */
+static void PRINTF_LIKE(2, 3)
+ write_to_client(struct client *c, const char *fmt, ...)
{
va_list ap;
char buf[WRBUFSZ];
}
}
-static void reply(struct client *c, const char *ty, const char *msg)
+/* Format a reply to the client, with the form LPORT:RPORT:TY:TOK0[:TOK1].
+ * Typically, TY will be `ERROR' or `USERID'. In the former case, TOK0 will
+ * be the error token and TOK1 will be null; in the latter case, TOK0 will be
+ * the operating system and TOK1 the user name.
+ */
+static void reply(struct client *c, const char *ty,
+ const char *tok0, const char *tok1)
{
- write_to_client(c, "%u,%u:%s:%s\r\n",
- c->q.s[L].port, c->q.s[R].port, ty, msg);
+ write_to_client(c, "%u,%u:%s:%s%s%s\r\n",
+ c->q.s[L].port, c->q.s[R].port, ty,
+ tok0, tok1 ? ":" : "", tok1 ? tok1 : "");
}
+/* Mapping from error codes to their protocol tokens. */
const char *const errtok[] = {
#define DEFTOK(err, tok) tok,
ERROR(DEFTOK)
#undef DEFTOK
};
+/* Report an error with code ERR to the client. */
static void reply_error(struct client *c, unsigned err)
{
assert(err < E_LIMIT);
- reply(c, "ERROR", errtok[err]);
+ reply(c, "ERROR", errtok[err], 0);
}
-static void skipws(const char **pp)
- { while (isspace((unsigned char )**pp)) (*pp)++; }
+/*----- NAT proxy functions -----------------------------------------------*/
-static int idtoken(const char **pp, char *q, size_t n)
+/* Cancel the proxy operation PX, closing the connection and releasing
+ * resources. This is used for both normal and unexpected closures.
+ */
+static void cancel_proxy(struct proxy *px)
{
- const char *p = *pp;
-
- skipws(&p);
- n--;
- for (;;) {
- if (*p == ':' || *p <= 32 || *p >= 127) break;
- if (!n) return (-1);
- *q++ = *p++;
- n--;
+ if (px->fd == -1)
+ conn_kill(&px->cn);
+ else {
+ close(px->fd);
+ selbuf_disable(&px->b);
}
- *q++ = 0;
- *pp = p;
- return (0);
+ px->c->px = 0;
+ selbuf_enable(&px->c->b);
+ px->next = dead_proxies;
+ dead_proxies = px;
}
-static int unum(const char **pp, unsigned *ii, unsigned min, unsigned max)
+/* Delayed destruction of unsafe parts of proxies. */
+static void reap_dead_proxies(void)
{
- char *q;
- unsigned long i;
- int e;
+ struct proxy *px, *pp;
- skipws(pp);
- if (!isdigit((unsigned char)**pp)) return (-1);
- e = errno; errno = 0;
- i = strtoul(*pp, &q, 10);
- if (errno) return (-1);
- *pp = q;
- errno = e;
- if (i < min || i > max) return (-1);
- *ii = i;
- return (0);
+ for (px = dead_proxies; px; px = pp) {
+ pp = px->next;
+ if (px->fd != -1) {
+ selbuf_destroy(&px->b);
+ free_writebuf(&px->wb);
+ }
+ xfree(px);
+ }
+ dead_proxies = 0;
}
+/* Notification that a line (presumably a reply) has been received from the
+ * server. We should check it, log it, and propagate the answer back.
+ * Whatever happens, this proxy operation is now complete.
+ */
static void proxy_line(char *line, size_t sz, void *p)
{
struct proxy *px = p;
const char *q = line;
unsigned lp, rp;
+ /* Trim trailing space. */
while (sz && isspace((unsigned char)line[sz - 1])) sz--;
- printf("received proxy line from %s: %s\n", px->nat, line);
+ /* Parse the port numbers. These should match the request. */
if (unum(&q, &lp, 1, 65535)) goto syntax;
skipws(&q); if (*q != ',') goto syntax; q++;
if (unum(&q, &rp, 1, 65535)) goto syntax;
skipws(&q); if (*q != ':') goto syntax; q++;
if (lp != px->c->q.u.nat.port || rp != px->c->q.s[R].port) goto syntax;
+
+ /* Find out what kind of reply this is. */
if (idtoken(&q, buf, sizeof(buf))) goto syntax;
skipws(&q); if (*q != ':') goto syntax; q++;
+
if (strcmp(buf, "ERROR") == 0) {
+
+ /* Report the error without interpreting it. It might be meaningful to
+ * the client.
+ */
skipws(&q);
logmsg(&px->c->q, LOG_ERR, "proxy error from %s: %s", px->nat, q);
- reply(px->c, "ERROR", q);
+ reply(px->c, "ERROR", q, 0);
+
} else if (strcmp(buf, "USERID") == 0) {
+
+ /* Parse out the operating system and user name, and pass them on. */
if (idtoken(&q, buf, sizeof(buf))) goto syntax;
skipws(&q); if (*q != ':') goto syntax; q++;
skipws(&q);
logmsg(&px->c->q, LOG_ERR, "user `%s'; proxy = %s, os = %s",
q, px->nat, buf);
- write_to_client(px->c, "%u,%u:USERID:%s:%s\r\n",
- px->c->q.s[L].port, px->c->q.s[R].port, buf, q);
+ reply(px->c, "USERID", buf, q);
+
} else
goto syntax;
goto done;
syntax:
+ /* We didn't understand the message from the client. */
logmsg(&px->c->q, LOG_ERR, "failed to parse response from %s", px->nat);
reply_error(px->c, E_UNKNOWN);
done:
+ /* All finished, no matter what. */
cancel_proxy(px);
}
+/* Notification that we have written the query to the server. Await a
+ * response if successful.
+ */
static void done_proxy_write(int err, void *p)
{
struct proxy *px = p;
selbuf_enable(&px->b);
}
+/* Notification that the connection to the server is either established or
+ * failed. In the former case, queue the right query.
+ */
static void proxy_connected(int fd, void *p)
{
struct proxy *px = p;
char buf[16];
int n;
+ /* If the connection failed then report the problem and give up. */
if (fd < 0) {
logmsg(&px->c->q, LOG_ERR,
"failed to make %s proxy connection to %s: %s",
return;
}
+ /* We're now ready to go, so set things up. */
px->fd = fd;
selbuf_init(&px->b, &sel, fd, proxy_line, px);
selbuf_setsize(&px->b, 1024);
selbuf_disable(&px->b);
init_writebuf(&px->wb, fd, done_proxy_write, px);
+ /* Write the query. This buffer is large enough because we've already
+ * range-checked the remote the port number and the local one came from the
+ * kernel, which we trust not to do anything stupid.
+ */
n = sprintf(buf, "%u,%u\r\n", px->c->q.u.nat.port, px->c->q.s[R].port);
queue_write(&px->wb, buf, n);
}
+/* Proxy the query through to a client machine for which we're providing NAT
+ * disservice.
+ */
static void proxy_query(struct client *c)
{
struct socket s;
struct proxy *px;
int fd;
+ /* Allocate the context structure for the NAT. */
px = xmalloc(sizeof(*px));
+
+ /* We'll use the client host's address in lots of log messages, so we may
+ * as well format it once and use it over and over.
+ */
inet_ntop(c->q.ao->af, &c->q.u.nat.addr, px->nat, sizeof(px->nat));
+ /* Create the socket for the connection. */
if ((fd = socket(c->q.ao->af, SOCK_STREAM, 0)) < 0) {
logmsg(&c->q, LOG_ERR, "failed to make %s socket for proxy: %s",
c->l->ao->name, strerror(errno));
goto err_0;
}
-
- if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
- logmsg(&c->q, LOG_ERR, "failed to set %s proxy socket nonblocking: %s",
- c->l->ao->name, strerror(errno));
- goto err_1;
- }
-
+ if (fix_up_socket(fd, "proxy")) goto err_1;
+
+ /* Set up the connection to the client host. The connection interface is a
+ * bit broken: if the connection completes immediately, then the callback
+ * function is called synchronously, and that might decide to shut
+ * everything down. So we must have fully initialized our context before
+ * calling `conn_init', and mustn't touch it again afterwards -- since the
+ * block may have been freed.
+ */
s = c->q.u.nat;
s.port = 113;
c->l->ao->socket_to_sockaddr(&s, &ss, &ssz);
selbuf_disable(&c->b);
+ c->px = px; px->c = c;
+ px->fd = -1;
if (conn_init(&px->cn, &sel, fd, (struct sockaddr *)&ss, ssz,
proxy_connected, px)) {
logmsg(&c->q, LOG_ERR, "failed to make %s proxy connection to %s: %s",
goto err_2;
}
- c->px = px; px->c = c;
- px->fd = -1;
+ /* All ready to go. */
return;
+ /* Tidy up after various kinds of failures. */
err_2:
selbuf_enable(&c->b);
err_1:
reply_error(c, E_UNKNOWN);
}
-static const struct policy default_policy = POLICY_INIT(A_NAME);
+/*----- Client connection functions ---------------------------------------*/
+/* Disconnect a client, freeing up any associated resources. */
+static void disconnect_client(struct client *c)
+{
+ selbuf_disable(&c->b);
+ close(c->fd);
+ sel_rmtimer(&c->t);
+ free_writebuf(&c->wb);
+ if (c->px) cancel_proxy(c->px);
+ c->next = dead_clients;
+ dead_clients = c;
+}
+
+/* Throw away dead clients now that we've reached a safe point in the
+ * program.
+ */
+static void reap_dead_clients(void)
+{
+ struct client *c, *cc;
+ for (c = dead_clients; c; c = cc) {
+ cc = c->next;
+ selbuf_destroy(&c->b);
+ xfree(c);
+ }
+ dead_clients = 0;
+}
+
+/* Time out a client because it's been idle for too long. */
+static void timeout_client(struct timeval *tv, void *p)
+{
+ struct client *c = p;
+ logmsg(&c->q, LOG_NOTICE, "timing out idle or stuck client");
+ sel_addtimer(&sel, &c->t, tv, timeout_client, 0);
+ disconnect_client(c);
+}
+
+/* Reset the client idle timer, as a result of activity. Set EXISTP if
+ * there is an existing timer which needs to be removed.
+ */
+static void reset_client_timer(struct client *c, int existp)
+{
+ struct timeval tv;
+
+ gettimeofday(&tv, 0);
+ tv.tv_sec += 30;
+ if (existp) sel_rmtimer(&c->t);
+ sel_addtimer(&sel, &c->t, &tv, timeout_client, c);
+}
+
+/* Write a pseudorandom token into the buffer at P, which must have space for
+ * at least TOKENSZ bytes.
+ */
+#define TOKENRANDSZ 8
+#define TOKENSZ ((4*TOKENRANDSZ + 5)/3)
static void user_token(char *p)
{
- static const char tokmap[64] =
- "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-";
unsigned a = 0;
unsigned b = 0;
int i;
-#define TOKENSZ 8
+ static const char tokmap[64] =
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-";
- if (tokenptr + TOKENSZ >= sizeof(tokenbuf)) {
- if (read(randfd, tokenbuf, sizeof(tokenbuf)) < sizeof(tokenbuf))
- die(1, "unexpected short read or error from `/dev/urandom'");
+ /* If there's not enough pseudorandom stuff lying around, then read more
+ * from the kernel.
+ */
+ if (tokenptr + TOKENRANDSZ >= sizeof(tokenbuf)) {
+ fill_random(tokenbuf, sizeof(tokenbuf));
tokenptr = 0;
}
- for (i = 0; i < TOKENSZ; i++) {
+ /* Now encode the bytes using a slightly tweaked base-64 encoding. Read
+ * bytes into the accumulator and write out characters while there's
+ * enough material.
+ */
+ for (i = 0; i < TOKENRANDSZ; i++) {
a = (a << 8) | tokenbuf[tokenptr++]; b += 8;
while (b >= 6) {
b -= 6;
*p++ = tokmap[(a >> b) & 0x3f];
}
}
+
+ /* If there's anything left in the accumulator then flush it out. */
if (b)
*p++ = tokmap[(a << (6 - b)) & 0x3f];
+
+ /* Null-terminate the token. */
*p++ = 0;
}
+/* Notification that a line has been received from the client. Parse it,
+ * find out about the connection it's referring to, apply the relevant
+ * policy rules, and produce a response. This is where almost everything
+ * interesting happens.
+ */
static void client_line(char *line, size_t len, void *p)
{
struct client *c = p;
struct policy upol = POLICY_INIT(A_LIMIT);
struct policy_file pf;
char buf[16];
- int i;
+ int i, t;
+ /* If the connection has closed, then tidy stuff away. */
+ c->q.s[R].addr = c->raddr;
c->q.s[L].port = c->q.s[R].port = 0;
if (!line) {
disconnect_client(c);
return;
}
- if (fwatch_update(&polfw, "yaid.policy")) {
- logmsg(0, LOG_INFO, "reload master policy file `%s'", "yaid.policy");
- load_policy_file("yaid.policy", &policy);
+ /* Client activity, so update the timer. */
+ reset_client_timer(c, 1);
+
+ /* See if the policy file has changed since we last looked. If so, try to
+ * read the new version.
+ */
+ if (fwatch_update(&polfw, policyfile)) {
+ logmsg(0, LOG_INFO, "reload master policy file `%s'", policyfile);
+ load_policy_file(policyfile, &policy);
}
+ /* Read the local and remote port numbers into the query structure. */
q = line;
if (unum(&q, &c->q.s[L].port, 1, 65535)) goto bad;
skipws(&q); if (*q != ',') goto bad; q++;
if (unum(&q, &c->q.s[R].port, 1, 65535)) goto bad;
skipws(&q); if (*q) goto bad;
+ /* Identify the connection. Act on the result. */
identify(&c->q);
switch (c->q.resp) {
+
case R_UID:
+ /* We found a user. Track down the user's password entry, because
+ * we'll want that later. Most of the processing for this case is
+ * below.
+ */
if ((pw = getpwuid(c->q.u.uid)) == 0) {
logmsg(&c->q, LOG_ERR, "no passwd entry for user %d", c->q.u.uid);
reply_error(c, E_NOUSER);
return;
}
break;
+
case R_NAT:
+ /* We've acted as a NAT for this connection. Proxy the query through
+ * to the actal client host.
+ */
proxy_query(c);
return;
+
case R_ERROR:
- /* Should already be logged. */
+ /* We failed to identify the connection for some reason. We should
+ * already have logged an error, so there's not much to do here.
+ */
reply_error(c, c->q.u.error);
return;
+
default:
+ /* Something happened that we don't understand. */
abort();
}
+ /* Search the table of policy rules to find a match. */
for (i = 0; i < DA_LEN(&policy); i++) {
pol = &DA(&policy)[i];
if (!match_policy(pol, &c->q)) continue;
- if (pol->act.act != A_USER)
- goto match;
+
+ /* If this is something simple, then apply the resulting policy rule. */
+ if (pol->act.act != A_USER) goto match;
+
+ /* The global policy has decided to let the user have a say, so we must
+ * parse the user file.
+ */
DRESET(&d);
dstr_putf(&d, "%s/.yaid.policy", pw->pw_dir);
- if (open_policy_file(&pf, d.buf, "user policy file", &c->q))
+ if (open_policy_file(&pf, d.buf, "user policy file", &c->q, OPF_NOENTOK))
continue;
- while (!read_policy_file(&pf)) {
+ while ((t = read_policy_file(&pf)) < T_ERROR) {
+
+ /* Give up after 100 lines or if there's an error. If the user's
+ * policy is that complicated, something's gone very wrong. Or there's
+ * too much commentary or something.
+ */
if (pf.lno > 100) {
logmsg(&c->q, LOG_ERR, "%s:%d: user policy file too long",
pf.name, pf.lno);
break;
}
+
+ /* If this was a blank line, just go around again. */
+ if (t != T_OK) continue;
+
+ /* If this isn't a match, go around for the next rule. */
if (!match_policy(&pf.p, &c->q)) continue;
+
+ /* Check that the user is allowed to request this action. If not, see
+ * if there's a more acceptable action later on.
+ */
if (!(pol->act.u.user & (1 << pf.p.act.act))) {
logmsg(&c->q, LOG_ERR,
"%s:%d: user action forbidden by global policy",
pf.name, pf.lno);
continue;
}
+
+ /* We've found a match, so grab it, close the file, and say we're
+ * done.
+ */
upol = pf.p; pol = &upol;
init_policy(&pf.p);
close_policy_file(&pf);
+ DDESTROY(&d);
goto match;
}
close_policy_file(&pf);
+ DDESTROY(&d);
}
+
+ /* No match: apply the built-in default policy. */
pol = &default_policy;
match:
- DDESTROY(&d);
switch (pol->act.act) {
+
case A_NAME:
+ /* Report the actual user's name. */
logmsg(&c->q, LOG_INFO, "user `%s' (%d)", pw->pw_name, c->q.u.uid);
- reply(c, "USERID:UNIX", pw->pw_name);
+ reply(c, "USERID", "UNIX", pw->pw_name);
break;
+
case A_TOKEN:
+ /* Report an arbitrary token which we can look up in our log file. */
user_token(buf);
logmsg(&c->q, LOG_INFO, "user `%s' (%d); token = %s",
pw->pw_name, c->q.u.uid, buf);
- reply(c, "USERID:OTHER", buf);
+ reply(c, "USERID", "OTHER", buf);
break;
+
case A_DENY:
+ /* Deny that there's anyone there at all. */
logmsg(&c->q, LOG_INFO, "user `%s' (%d); denying",
pw->pw_name, c->q.u.uid);
break;
+
case A_HIDE:
+ /* Report the user as being hidden. */
logmsg(&c->q, LOG_INFO, "user `%s' (%d); hiding",
pw->pw_name, c->q.u.uid);
reply_error(c, E_HIDDEN);
break;
+
case A_LIE:
+ /* Tell an egregious lie about who the user is. */
logmsg(&c->q, LOG_INFO, "user `%s' (%d); lie = `%s'",
pw->pw_name, c->q.u.uid, pol->act.u.lie);
- reply(c, "USERID:UNIX", pol->act.u.lie);
+ reply(c, "USERID", "UNIX", pol->act.u.lie);
break;
+
default:
+ /* Something has gone very wrong. */
abort();
}
+ /* All done. */
free_policy(&upol);
return;
disconnect_client(c);
}
+/* Notification that a new client has connected. Prepare to read a query. */
static void accept_client(int fd, unsigned mode, void *p)
{
struct listen *l = p;
struct client *c;
struct sockaddr_storage ssr, ssl;
- size_t ssz = sizeof(ssr);
+ socklen_t ssz = sizeof(ssr);
int sk;
+ /* Accept the new connection. */
if ((sk = accept(fd, (struct sockaddr *)&ssr, &ssz)) < 0) {
if (errno != EAGAIN && errno == EWOULDBLOCK) {
logmsg(0, LOG_ERR, "failed to accept incoming %s connection: %s",
}
return;
}
+ if (fix_up_socket(sk, "incoming client")) { close(sk); return; }
+ /* Build a client block and fill it in. */
c = xmalloc(sizeof(*c));
c->l = l;
c->q.ao = l->ao;
- l->ao->sockaddr_to_addr(&ssr, &c->q.s[R].addr);
+
+ /* Collect the local and remote addresses. */
+ l->ao->sockaddr_to_addr(&ssr, &c->raddr);
ssz = sizeof(ssl);
if (getsockname(sk, (struct sockaddr *)&ssl, &ssz)) {
logmsg(0, LOG_ERR,
l->ao->sockaddr_to_addr(&ssl, &c->q.s[L].addr);
c->q.s[L].port = c->q.s[R].port = 0;
- /* logmsg(&c->q, LOG_INFO, "accepted %s connection", l->ao->name); */
-
+ /* Set stuff up for reading the query and sending responses. */
selbuf_init(&c->b, &sel, sk, client_line, c);
selbuf_setsize(&c->b, 1024);
+ reset_client_timer(c, 0);
c->fd = sk;
c->px = 0;
init_writebuf(&c->wb, sk, done_client_write, c);
}
+/*----- Main code ---------------------------------------------------------*/
+
+/* Set up a listening socket for the address family described by AO,
+ * listening on PORT.
+ */
static int make_listening_socket(const struct addrops *ao, int port)
{
int fd;
struct listen *l;
size_t ssz;
+ /* Make the socket. */
if ((fd = socket(ao->af, SOCK_STREAM, 0)) < 0) {
if (errno == EAFNOSUPPORT) return (-1);
die(1, "failed to create %s listening socket: %s",
ao->name, strerror(errno));
}
- setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
+
+ /* Build the appropriate local address. */
s.addr = *ao->any;
s.port = port;
ao->socket_to_sockaddr(&s, &ss, &ssz);
+
+ /* Perform any initialization specific to the address type. */
if (ao->init_listen_socket(fd)) {
die(1, "failed to initialize %s listening socket: %s",
ao->name, strerror(errno));
}
+
+ /* Bind to the address. */
+ setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
if (bind(fd, (struct sockaddr *)&ss, ssz)) {
die(1, "failed to bind %s listening socket: %s",
ao->name, strerror(errno));
}
+
+ /* Avoid unpleasant race conditions. */
if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
die(1, "failed to set %s listening socket nonblocking: %s",
ao->name, strerror(errno));
}
+
+ /* Prepare to listen. */
if (listen(fd, 5))
die(1, "failed to listen for %s: %s", ao->name, strerror(errno));
+ /* Make a record of all of this. */
l = xmalloc(sizeof(*l));
l->ao = ao;
sel_initfile(&sel, &l->f, fd, SEL_READ, accept_client, l);
sel_addfile(&l->f);
+ /* Done. */
return (0);
}
+/* Quit because of a fatal signal. */
+static void NORETURN quit(int sig, void *p)
+{
+ const char *signame = p;
+
+ logmsg(0, LOG_NOTICE, "shutting down on %s", signame);
+ if (pidfile) unlink(pidfile);
+ exit(0);
+}
+
+/* Answer whether the string pointed to by P consists entirely of digits. */
+static int numericp(const char *p)
+{
+ while (*p)
+ if (!isdigit((unsigned char)*p++)) return (0);
+ return (1);
+}
+
+static void usage(FILE *fp)
+{
+ pquis(fp, "Usage: $ [-Dl] [-G GROUP] [-U USER] [-P FILE] "
+ "[-c FILE] [-p PORT]\n");
+}
+
+static void version(FILE *fp)
+ { pquis(fp, "$, version " VERSION "\n"); }
+
+static void help(FILE *fp)
+{
+ version(fp); fputc('\n', fp);
+ usage(fp);
+ fputs("\n\
+Yet Another Ident Daemon. Really, the world doesn't need such a thing.\n\
+It's just a shame none of the others do the right things.\n\
+\n\
+Options:\n\
+\n\
+ -h, --help Show this help message.\n\
+ -v, --version Show the version number.\n\
+ -u, --usage Show a very short usage summary.\n\
+\n\
+ -D, --daemon Become a daemon, running in the background.\n\
+ -G, --group=GROUP Set group after initialization.\n\
+ -P, --pidfile=FILE Write process id to FILE.\n\
+ -U, --user=USER Set user after initialization.\n\
+ -c, --config=FILE Read global policy from FILE.\n\
+ -l, --syslog Write log messages using syslog(3).\n\
+ -p, --port=PORT Listen for connections on this port.\n",
+ fp);
+}
+
int main(int argc, char *argv[])
{
int port = 113;
+ uid_t u = -1;
+ gid_t g = -1;
+ struct passwd *pw = 0;
+ struct group *gr;
+ struct servent *s;
+ sig sigint, sigterm;
+ FILE *fp = 0;
+ int i;
+ unsigned f = 0;
+#define f_bogus 1u
+#define f_daemon 2u
const struct addrops *ao;
int any = 0;
ego(argv[0]);
- fwatch_init(&polfw, "yaid.policy");
- if (load_policy_file("yaid.policy", &policy))
- exit(1);
- { int i;
- for (i = 0; i < DA_LEN(&policy); i++)
- print_policy(&DA(&policy)[i]);
+ /* Parse command-line options. */
+ for (;;) {
+ const struct option opts[] = {
+ { "help", 0, 0, 'h' },
+ { "version", 0, 0, 'v' },
+ { "usage", 0, 0, 'u' },
+ { "daemon", 0, 0, 'D' },
+ { "group", OPTF_ARGREQ, 0, 'G' },
+ { "pidfile", OPTF_ARGREQ, 0, 'P' },
+ { "user", OPTF_ARGREQ, 0, 'U' },
+ { "config", OPTF_ARGREQ, 0, 'c' },
+ { "syslog", 0, 0, 'l' },
+ { "port", OPTF_ARGREQ, 0, 'p' },
+ { 0, 0, 0, 0 }
+ };
+
+ if ((i = mdwopt(argc, argv, "hvuDG:P:U:c:lp:", opts, 0, 0, 0)) < 0)
+ break;
+ switch (i) {
+ case 'h': help(stdout); exit(0);
+ case 'v': version(stdout); exit(0);
+ case 'u': usage(stdout); exit(0);
+ case 'D': f |= f_daemon; break;
+ case 'P': pidfile = optarg; break;
+ case 'c': policyfile = optarg; break;
+ case 'l': flags |= F_SYSLOG; break;
+ case 'G':
+ if (numericp(optarg))
+ g = atoi(optarg);
+ else if ((gr = getgrnam(optarg)) == 0)
+ die(1, "unknown group `%s'", optarg);
+ else
+ g = gr->gr_gid;
+ break;
+ case 'U':
+ if (numericp(optarg))
+ u = atoi(optarg);
+ else if ((pw = getpwnam(optarg)) == 0)
+ die(1, "unknown user `%s'", optarg);
+ else
+ u = pw->pw_uid;
+ break;
+ case 'p':
+ if (numericp(optarg))
+ port = atoi(optarg);
+ else if ((s = getservbyname(optarg, "tcp")) == 0)
+ die(1, "unknown service name `%s'", optarg);
+ else
+ port = ntohs(s->s_port);
+ break;
+ default: f |= f_bogus; break;
+ }
}
-
- if ((randfd = open("/dev/urandom", O_RDONLY)) < 0) {
- die(1, "failed to open `/dev/urandom' for reading: %s",
- strerror(errno));
+ if (optind < argc) f |= f_bogus;
+ if (f & f_bogus) { usage(stderr); exit(1); }
+
+ /* If a user has been requested, but no group, then find the user's primary
+ * group. If the user was given by name, then we already have a password
+ * entry and should use that, in case two differently-named users have the
+ * same uid but distinct gids.
+ */
+ if (u != -1 && g == -1) {
+ if (!pw && (pw = getpwuid(u)) == 0) {
+ die(1, "failed to find password entry for user %d: "
+ "request group explicitly", u);
+ }
+ g = pw->pw_gid;
}
+ /* Initialize system-specific machinery. */
+ init_sys();
+
+ /* Load the global policy rules. */
+ fwatch_init(&polfw, policyfile);
+ if (load_policy_file(policyfile, &policy))
+ exit(1);
+
+ /* Set up the I/O event system. */
sel_init(&sel);
+
+ /* Watch for some interesting signals. */
+ sig_init(&sel);
+ sig_add(&sigint, SIGINT, quit, "SIGINT");
+ sig_add(&sigterm, SIGTERM, quit, "SIGTERM");
+
+ /* Listen for incoming connections. */
for (ao = addroptab; ao->name; ao++)
if (!make_listening_socket(ao, port)) any = 1;
- if (!any)
- die(1, "no IP protocols supported");
+ if (!any) die(1, "no IP protocols supported");
+
+ /* Open the pidfile now, in case it's somewhere we can't write. */
+ if (pidfile && (fp = fopen(pidfile, "w")) == 0) {
+ die(1, "failed to open pidfile `%s' for writing: %s",
+ pidfile, strerror(errno));
+ }
+
+ /* If we're meant to use syslog, then open the log. */
+ if (flags & F_SYSLOG)
+ openlog(QUIS, 0, LOG_DAEMON);
+
+ /* Drop privileges. */
+ if ((g != -1 && (setegid(g) || setgid(g) ||
+ (getuid() == 0 && setgroups(1, &g)))) ||
+ (u != -1 && setuid(u)))
+ die(1, "failed to drop privileges: %s", strerror(errno));
- for (;;)
- if (sel_select(&sel)) die(1, "select failed: %s", strerror(errno));
+ /* Become a background process, if requested. */
+ if ((f & f_daemon) && daemonize())
+ die(1, "failed to become daemon: %s", strerror(errno));
+
+ /* Write the process id to the pidfile. */
+ if (fp) {
+ fprintf(fp, "%d\n", getpid());
+ fclose(fp);
+ }
+
+ /* And now we're going. */
+ flags |= F_RUNNING;
+
+ /* Read events and process them. */
+ for (;;) {
+ if (sel_select(&sel) && errno != EINTR)
+ die(1, "select failed: %s", strerror(errno));
+ reap_dead_proxies();
+ reap_dead_clients();
+ }
+ /* This just keeps the compiler happy. */
return (0);
}
~mdw / yaid / blobdiff