heimdal/lib/ipc/server.c

/*
 * Copyright (c) 2009 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Portions Copyright (c) 2009 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "hi_locl.h"
#include <assert.h>

#define MAX_PACKET_SIZE (128 * 1024)

struct heim_sipc {
    int (*release)(heim_sipc ctx);
    heim_ipc_callback callback;
    void *userctx;
    void *mech;
};

#if defined(__APPLE__) && defined(HAVE_GCD)

#include "heim_ipcServer.h"
#include "heim_ipc_reply.h"
#include "heim_ipc_async.h"

static dispatch_source_t timer;
static dispatch_queue_t timerq;
static uint64_t timeoutvalue;

static dispatch_queue_t eventq;

static dispatch_queue_t workq;

static void
default_timer_ev(void)
{
    exit(0);
}

static void (*timer_ev)(void) = default_timer_ev;

static void
set_timer(void)
{
    dispatch_source_set_timer(timer,
			      dispatch_time(DISPATCH_TIME_NOW,
					    timeoutvalue * NSEC_PER_SEC),
			      timeoutvalue * NSEC_PER_SEC, 1000000);
}

static void
init_globals(void)
{
    static dispatch_once_t once;
    dispatch_once(&once, ^{
	timerq = dispatch_queue_create("hiem-sipc-timer-q", NULL);
        timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, timerq);
	dispatch_source_set_event_handler(timer, ^{ timer_ev(); } );

	workq = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
	eventq = dispatch_queue_create("heim-ipc.event-queue", NULL);
    });
}

static void
suspend_timer(void)
{
    dispatch_suspend(timer);
}

static void
restart_timer(void)
{
    dispatch_sync(timerq, ^{ set_timer(); });
    dispatch_resume(timer);
}

struct mach_service {
    mach_port_t sport;
    dispatch_source_t source;
    dispatch_queue_t queue;
};

struct mach_call_ctx {
    mach_port_t reply_port;
    heim_icred cred;
    heim_idata req;
};


static void
mach_complete_sync(heim_sipc_call ctx, int returnvalue, heim_idata *reply)
{
    struct mach_call_ctx *s = (struct mach_call_ctx *)ctx;
    heim_ipc_message_inband_t replyin;
    mach_msg_type_number_t replyinCnt;
    heim_ipc_message_outband_t replyout;
    mach_msg_type_number_t replyoutCnt;
    kern_return_t kr;

    if (returnvalue) {
	/* on error, no reply */
	replyinCnt = 0;
	replyout = 0; replyoutCnt = 0;
	kr = KERN_SUCCESS;
    } else if (reply->length < 2048) {
	replyinCnt = reply->length;
	memcpy(replyin, reply->data, replyinCnt);
	replyout = 0; replyoutCnt = 0;
	kr = KERN_SUCCESS;
    } else {
	replyinCnt = 0;
	kr = vm_read(mach_task_self(),
		     (vm_address_t)reply->data, reply->length,
		     (vm_address_t *)&replyout, &replyoutCnt);
    }

    mheim_ripc_call_reply(s->reply_port, returnvalue,
			  replyin, replyinCnt,
			  replyout, replyoutCnt);

    heim_ipc_free_cred(s->cred);
    free(s->req.data);
    free(s);
    restart_timer();
}

static void
mach_complete_async(heim_sipc_call ctx, int returnvalue, heim_idata *reply)
{
    struct mach_call_ctx *s = (struct mach_call_ctx *)ctx;
    heim_ipc_message_inband_t replyin;
    mach_msg_type_number_t replyinCnt;
    heim_ipc_message_outband_t replyout;
    mach_msg_type_number_t replyoutCnt;
    kern_return_t kr;

    if (returnvalue) {
	/* on error, no reply */
	replyinCnt = 0;
	replyout = 0; replyoutCnt = 0;
	kr = KERN_SUCCESS;
    } else if (reply->length < 2048) {
	replyinCnt = reply->length;
	memcpy(replyin, reply->data, replyinCnt);
	replyout = 0; replyoutCnt = 0;
	kr = KERN_SUCCESS;
    } else {
	replyinCnt = 0;
	kr = vm_read(mach_task_self(),
		     (vm_address_t)reply->data, reply->length,
		     (vm_address_t *)&replyout, &replyoutCnt);
    }

    kr = mheim_aipc_acall_reply(s->reply_port, returnvalue,
				replyin, replyinCnt,
				replyout, replyoutCnt);
    heim_ipc_free_cred(s->cred);
    free(s->req.data);
    free(s);
    restart_timer();
}


kern_return_t
mheim_do_call(mach_port_t server_port,
	      audit_token_t client_creds,
	      mach_port_t reply_port,
	      heim_ipc_message_inband_t requestin,
	      mach_msg_type_number_t requestinCnt,
	      heim_ipc_message_outband_t requestout,
	      mach_msg_type_number_t requestoutCnt,
	      int *returnvalue,
	      heim_ipc_message_inband_t replyin,
	      mach_msg_type_number_t *replyinCnt,
	      heim_ipc_message_outband_t *replyout,
	      mach_msg_type_number_t *replyoutCnt)
{
    heim_sipc ctx = dispatch_get_context(dispatch_get_current_queue());
    struct mach_call_ctx *s;
    kern_return_t kr;
    uid_t uid;
    gid_t gid;
    pid_t pid;
    au_asid_t session;

    *replyout = NULL;
    *replyoutCnt = 0;
    *replyinCnt = 0;

    s = malloc(sizeof(*s));
    if (s == NULL)
	return KERN_MEMORY_FAILURE; /* XXX */

    s->reply_port = reply_port;

    audit_token_to_au32(client_creds, NULL, &uid, &gid, NULL, NULL, &pid, &session, NULL);

    kr = _heim_ipc_create_cred(uid, gid, pid, session, &s->cred);
    if (kr) {
	free(s);
	return kr;
    }

    suspend_timer();

    if (requestinCnt) {
	s->req.data = malloc(requestinCnt);
	memcpy(s->req.data, requestin, requestinCnt);
	s->req.length = requestinCnt;
    } else {
	s->req.data = malloc(requestoutCnt);
	memcpy(s->req.data, requestout, requestoutCnt);
	s->req.length = requestoutCnt;
    }

    dispatch_async(workq, ^{
	(ctx->callback)(ctx->userctx, &s->req, s->cred,
			mach_complete_sync, (heim_sipc_call)s);
    });

    return MIG_NO_REPLY;
}

kern_return_t
mheim_do_call_request(mach_port_t server_port,
		      audit_token_t client_creds,
		      mach_port_t reply_port,
		      heim_ipc_message_inband_t requestin,
		      mach_msg_type_number_t requestinCnt,
		      heim_ipc_message_outband_t requestout,
		      mach_msg_type_number_t requestoutCnt)
{
    heim_sipc ctx = dispatch_get_context(dispatch_get_current_queue());
    struct mach_call_ctx *s;
    kern_return_t kr;
    uid_t uid;
    gid_t gid;
    pid_t pid;
    au_asid_t session;

    s = malloc(sizeof(*s));
    if (s == NULL)
	return KERN_MEMORY_FAILURE; /* XXX */

    s->reply_port = reply_port;

    audit_token_to_au32(client_creds, NULL, &uid, &gid, NULL, NULL, &pid, &session, NULL);

    kr = _heim_ipc_create_cred(uid, gid, pid, session, &s->cred);
    if (kr) {
	free(s);
	return kr;
    }

    suspend_timer();

    if (requestinCnt) {
	s->req.data = malloc(requestinCnt);
	memcpy(s->req.data, requestin, requestinCnt);
	s->req.length = requestinCnt;
    } else {
	s->req.data = malloc(requestoutCnt);
	memcpy(s->req.data, requestout, requestoutCnt);
	s->req.length = requestoutCnt;
    }

    dispatch_async(workq, ^{
	(ctx->callback)(ctx->userctx, &s->req, s->cred,
			mach_complete_async, (heim_sipc_call)s);
    });

    return KERN_SUCCESS;
}

static int
mach_init(const char *service, mach_port_t sport, heim_sipc ctx)
{
    struct mach_service *s;
    char *name;

    init_globals();

    s = calloc(1, sizeof(*s));
    if (s == NULL)
	return ENOMEM;

    asprintf(&name, "heim-ipc-mach-%s", service);

    s->queue = dispatch_queue_create(name, NULL);
    free(name);
    s->sport = sport;

    s->source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MACH_RECV,
				       s->sport, 0, s->queue);
    if (s->source == NULL) {
	dispatch_release(s->queue);
	free(s);
	return ENOMEM;
    }
    ctx->mech = s;

    dispatch_set_context(s->queue, ctx);
    dispatch_set_context(s->source, s);

    dispatch_source_set_event_handler(s->source, ^{
	    dispatch_mig_server(s->source, sizeof(union __RequestUnion__mheim_do_mheim_ipc_subsystem), mheim_ipc_server);
	});

    dispatch_source_set_cancel_handler(s->source, ^{
	    heim_sipc sctx = dispatch_get_context(dispatch_get_current_queue());
	    struct mach_service *st = sctx->mech;
	    mach_port_mod_refs(mach_task_self(), st->sport,
			       MACH_PORT_RIGHT_RECEIVE, -1);
	    dispatch_release(st->queue);
	    dispatch_release(st->source);
	    free(st);
	    free(sctx);
	});

    dispatch_resume(s->source);

    return 0;
}

static int
mach_release(heim_sipc ctx)
{
    struct mach_service *s = ctx->mech;
    dispatch_source_cancel(s->source);
    dispatch_release(s->source);
    return 0;
}

static mach_port_t
mach_checkin_or_register(const char *service)
{
    mach_port_t mp;
    kern_return_t kr;

    kr = bootstrap_check_in(bootstrap_port, service, &mp);
    if (kr == KERN_SUCCESS)
	return mp;

#if __MAC_OS_X_VERSION_MIN_REQUIRED <= 1050
    /* Pre SnowLeopard version */
    kr = mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &mp);
    if (kr != KERN_SUCCESS)
	return MACH_PORT_NULL;

    kr = mach_port_insert_right(mach_task_self(), mp, mp,
				MACH_MSG_TYPE_MAKE_SEND);
    if (kr != KERN_SUCCESS) {
	mach_port_destroy(mach_task_self(), mp);
	return MACH_PORT_NULL;
    }

    kr = bootstrap_register(bootstrap_port, rk_UNCONST(service), mp);
    if (kr != KERN_SUCCESS) {
	mach_port_destroy(mach_task_self(), mp);
	return MACH_PORT_NULL;
    }

    return mp;
#else
    return MACH_PORT_NULL;
#endif
}


#endif /* __APPLE__ && HAVE_GCD */


int
heim_sipc_launchd_mach_init(const char *service,
			    heim_ipc_callback callback,
			    void *user, heim_sipc *ctx)
{
#if defined(__APPLE__) && defined(HAVE_GCD)
    mach_port_t sport = MACH_PORT_NULL;
    heim_sipc c = NULL;
    int ret;

    *ctx = NULL;

    sport = mach_checkin_or_register(service);
    if (sport == MACH_PORT_NULL) {
	ret = ENOENT;
	goto error;
    }

    c = calloc(1, sizeof(*c));
    if (c == NULL) {
	ret = ENOMEM;
	goto error;
    }
    c->release = mach_release;
    c->userctx = user;
    c->callback = callback;

    ret = mach_init(service, sport, c);
    if (ret)
	goto error;

    *ctx = c;
    return 0;
 error:
    if (c)
	free(c);
    if (sport != MACH_PORT_NULL)
	mach_port_mod_refs(mach_task_self(), sport,
			   MACH_PORT_RIGHT_RECEIVE, -1);
    return ret;
#else /* !(__APPLE__ && HAVE_GCD) */
    *ctx = NULL;
    return EINVAL;
#endif /* __APPLE__ && HAVE_GCD */
}

struct client {
    int fd;
    heim_ipc_callback callback;
    void *userctx;
    int flags;
#define LISTEN_SOCKET	1
#define WAITING_READ	2
#define WAITING_WRITE	4
#define WAITING_CLOSE	8

#define HTTP_REPLY	16

#define INHERIT_MASK	0xffff0000
#define INCLUDE_ERROR_CODE (1 << 16)
#define ALLOW_HTTP	(1<<17)
#define UNIX_SOCKET	(1<<18)
    unsigned calls;
    size_t ptr, len;
    uint8_t *inmsg;
    size_t olen;
    uint8_t *outmsg;
#ifdef HAVE_GCD
    dispatch_source_t in;
    dispatch_source_t out;
#endif
    struct {
	uid_t uid;
	gid_t gid;
	pid_t pid;
    } unixrights;
};

#ifndef HAVE_GCD
static unsigned num_clients = 0;
static struct client **clients = NULL;
#endif

static void handle_read(struct client *);
static void handle_write(struct client *);
static int maybe_close(struct client *);

/*
 * Update peer credentials from socket.
 *
 * SCM_CREDS can only be updated the first time there is read data to
 * read from the filedescriptor, so if we read do it before this
 * point, the cred data might not be is not there yet.
 */

static int
update_client_creds(struct client *c)
{
#ifdef HAVE_GETPEERUCRED
    /* Solaris 10 */
    {
	ucred_t *peercred;

	if (getpeerucred(c->fd, &peercred) != 0) {
	    c->unixrights.uid = ucred_geteuid(peercred);
	    c->unixrights.gid = ucred_getegid(peercred);
	    c->unixrights.pid = 0;
	    ucred_free(peercred);
	    return 1;
	}
    }
#endif
#ifdef HAVE_GETPEEREID
    /* FreeBSD, OpenBSD */
    {
	uid_t uid;
	gid_t gid;

	if (getpeereid(c->fd, &uid, &gid) == 0) {
	    c->unixrights.uid = uid;
	    c->unixrights.gid = gid;
	    c->unixrights.pid = 0;
	    return 1;
	}
    }
#endif
#if defined(SO_PEERCRED) && defined(__linux__)
    /* Linux */
    {
	struct ucred pc;
	socklen_t pclen = sizeof(pc);

	if (getsockopt(c->fd, SOL_SOCKET, SO_PEERCRED, (void *)&pc, &pclen) == 0) {
	    c->unixrights.uid = pc.uid;
	    c->unixrights.gid = pc.gid;
	    c->unixrights.pid = pc.pid;
	    return 1;
	}
    }
#endif
#if defined(LOCAL_PEERCRED) && defined(XUCRED_VERSION)
    {
	struct xucred peercred;
	socklen_t peercredlen = sizeof(peercred);

	if (getsockopt(c->fd, LOCAL_PEERCRED, 1,
		       (void *)&peercred, &peercredlen) == 0
	    && peercred.cr_version == XUCRED_VERSION)
	{
	    c->unixrights.uid = peercred.cr_uid;
	    c->unixrights.gid = peercred.cr_gid;
	    c->unixrights.pid = 0;
	    return 1;
	}
    }
#endif
#if defined(SOCKCREDSIZE) && defined(SCM_CREDS)
    /* NetBSD */
    if (c->unixrights.uid == (uid_t)-1) {
	struct msghdr msg;
	socklen_t crmsgsize;
	void *crmsg;
	struct cmsghdr *cmp;
	struct sockcred *sc;

	memset(&msg, 0, sizeof(msg));
	crmsgsize = CMSG_SPACE(SOCKCREDSIZE(NGROUPS));
	if (crmsgsize == 0)
	    return 1 ;

	crmsg = malloc(crmsgsize);
	if (crmsg == NULL)
	    goto failed_scm_creds;

	memset(crmsg, 0, crmsgsize);

	msg.msg_control = crmsg;
	msg.msg_controllen = crmsgsize;

	if (recvmsg(c->fd, &msg, 0) < 0) {
	    free(crmsg);
	    goto failed_scm_creds;
	}

	if (msg.msg_controllen == 0 || (msg.msg_flags & MSG_CTRUNC) != 0) {
	    free(crmsg);
	    goto failed_scm_creds;
	}

	cmp = CMSG_FIRSTHDR(&msg);
	if (cmp->cmsg_level != SOL_SOCKET || cmp->cmsg_type != SCM_CREDS) {
	    free(crmsg);
	    goto failed_scm_creds;
	}

	sc = (struct sockcred *)(void *)CMSG_DATA(cmp);

	c->unixrights.uid = sc->sc_euid;
	c->unixrights.gid = sc->sc_egid;
	c->unixrights.pid = 0;

	free(crmsg);
	return 1;
    } else {
	/* we already got the cred, just return it */
	return 1;
    }
 failed_scm_creds:
#endif
    return 0;
}


static struct client *
add_new_socket(int fd,
	       int flags,
	       heim_ipc_callback callback,
	       void *userctx)
{
    struct client *c;
    int fileflags;

    c = calloc(1, sizeof(*c));
    if (c == NULL)
	return NULL;

    if (flags & LISTEN_SOCKET) {
	c->fd = fd;
    } else {
	c->fd = accept(fd, NULL, NULL);
	if(c->fd < 0) {
	    free(c);
	    return NULL;
	}
    }

    c->flags = flags;
    c->callback = callback;
    c->userctx = userctx;

    fileflags = fcntl(c->fd, F_GETFL, 0);
    fcntl(c->fd, F_SETFL, fileflags | O_NONBLOCK);

#ifdef HAVE_GCD
    init_globals();

    c->in = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ,
				   c->fd, 0, eventq);
    c->out = dispatch_source_create(DISPATCH_SOURCE_TYPE_WRITE,
				    c->fd, 0, eventq);

    dispatch_source_set_event_handler(c->in, ^{
	    int rw = (c->flags & WAITING_WRITE);
	    handle_read(c);
	    if (rw == 0 && (c->flags & WAITING_WRITE))
		dispatch_resume(c->out);
	    if ((c->flags & WAITING_READ) == 0)
		dispatch_suspend(c->in);
	    maybe_close(c);
	});
    dispatch_source_set_event_handler(c->out, ^{
	    handle_write(c);
	    if ((c->flags & WAITING_WRITE) == 0) {
		dispatch_suspend(c->out);
	    }
	    maybe_close(c);
	});

    dispatch_resume(c->in);
#else
    clients = erealloc(clients, sizeof(clients[0]) * (num_clients + 1));
    clients[num_clients] = c;
    num_clients++;
#endif

    return c;
}

static int
maybe_close(struct client *c)
{
    if (c->calls != 0)
	return 0;
    if (c->flags & (WAITING_READ|WAITING_WRITE))
	return 0;

#ifdef HAVE_GCD
    dispatch_source_cancel(c->in);
    if ((c->flags & WAITING_READ) == 0)
	dispatch_resume(c->in);
    dispatch_release(c->in);

    dispatch_source_cancel(c->out);
    if ((c->flags & WAITING_WRITE) == 0)
	dispatch_resume(c->out);
    dispatch_release(c->out);
#endif
    close(c->fd); /* ref count fd close */
    free(c);
    return 1;
}


struct socket_call {
    heim_idata in;
    struct client *c;
    heim_icred cred;
};

static void
output_data(struct client *c, const void *data, size_t len)
{
    if (c->olen + len < c->olen)
	abort();
    c->outmsg = erealloc(c->outmsg, c->olen + len);
    memcpy(&c->outmsg[c->olen], data, len);
    c->olen += len;
    c->flags |= WAITING_WRITE;
}

static void
socket_complete(heim_sipc_call ctx, int returnvalue, heim_idata *reply)
{
    struct socket_call *sc = (struct socket_call *)ctx;
    struct client *c = sc->c;

    /* double complete ? */
    if (c == NULL)
	abort();

    if ((c->flags & WAITING_CLOSE) == 0) {
	uint32_t u32;

	/* length */
	u32 = htonl(reply->length);
	output_data(c, &u32, sizeof(u32));

	/* return value */
	if (c->flags & INCLUDE_ERROR_CODE) {
	    u32 = htonl(returnvalue);
	    output_data(c, &u32, sizeof(u32));
	}

	/* data */
	output_data(c, reply->data, reply->length);

	/* if HTTP, close connection */
	if (c->flags & HTTP_REPLY) {
	    c->flags |= WAITING_CLOSE;
	    c->flags &= ~WAITING_READ;
	}
    }

    c->calls--;
    if (sc->cred)
	heim_ipc_free_cred(sc->cred);
    free(sc->in.data);
    sc->c = NULL; /* so we can catch double complete */
    free(sc);

    maybe_close(c);
}

/* remove HTTP %-quoting from buf */
static int
de_http(char *buf)
{
    unsigned char *p, *q;
    for(p = q = (unsigned char *)buf; *p; p++, q++) {
	if(*p == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
	    unsigned int x;
	    if(sscanf((char *)p + 1, "%2x", &x) != 1)
		return -1;
	    *q = x;
	    p += 2;
	} else
	    *q = *p;
    }
    *q = '\0';
    return 0;
}

static struct socket_call *
handle_http_tcp(struct client *c)
{
    struct socket_call *cs;
    char *s, *p, *t;
    void *data;
    char *proto;
    int len;

    s = (char *)c->inmsg;

    p = strstr(s, "\r\n");
    if (p == NULL)
	return NULL;

    *p = 0;

    p = NULL;
    t = strtok_r(s, " \t", &p);
    if (t == NULL)
	return NULL;

    t = strtok_r(NULL, " \t", &p);
    if (t == NULL)
	return NULL;

    data = malloc(strlen(t));
    if (data == NULL)
	return NULL;

    if(*t == '/')
	t++;
    if(de_http(t) != 0) {
	free(data);
	return NULL;
    }
    proto = strtok_r(NULL, " \t", &p);
    if (proto == NULL) {
	free(data);
	return NULL;
    }
    len = rk_base64_decode(t, data);
    if(len <= 0){
	const char *msg =
	    " 404 Not found\r\n"
	    "Server: Heimdal/" VERSION "\r\n"
	    "Cache-Control: no-cache\r\n"
	    "Pragma: no-cache\r\n"
	    "Content-type: text/html\r\n"
	    "Content-transfer-encoding: 8bit\r\n\r\n"
	    "<TITLE>404 Not found</TITLE>\r\n"
	    "<H1>404 Not found</H1>\r\n"
	    "That page doesn't exist, maybe you are looking for "
	    "<A HREF=\"http://www.h5l.org/\">Heimdal</A>?\r\n";
	free(data);
	output_data(c, proto, strlen(proto));
	output_data(c, msg, strlen(msg));
	return NULL;
    }

    cs = emalloc(sizeof(*cs));
    cs->c = c;
    cs->in.data = data;
    cs->in.length = len;
    c->ptr = 0;

    {
	const char *msg =
	    " 200 OK\r\n"
	    "Server: Heimdal/" VERSION "\r\n"
	    "Cache-Control: no-cache\r\n"
	    "Pragma: no-cache\r\n"
	    "Content-type: application/octet-stream\r\n"
	    "Content-transfer-encoding: binary\r\n\r\n";
	output_data(c, proto, strlen(proto));
	output_data(c, msg, strlen(msg));
    }

    return cs;
}


static void
handle_read(struct client *c)
{
    ssize_t len;
    uint32_t dlen;

    if (c->flags & LISTEN_SOCKET) {
	add_new_socket(c->fd,
		       WAITING_READ | (c->flags & INHERIT_MASK),
		       c->callback,
		       c->userctx);
	return;
    }

    if (c->ptr - c->len < 1024) {
	c->inmsg = erealloc(c->inmsg,
			    c->len + 1024);
	c->len += 1024;
    }

    len = read(c->fd, c->inmsg + c->ptr, c->len - c->ptr);
    if (len <= 0) {
	c->flags |= WAITING_CLOSE;
	c->flags &= ~WAITING_READ;
	return;
    }
    c->ptr += len;
    if (c->ptr > c->len)
	abort();

    while (c->ptr >= sizeof(dlen)) {
	struct socket_call *cs;

	if((c->flags & ALLOW_HTTP) && c->ptr >= 4 &&
	   strncmp((char *)c->inmsg, "GET ", 4) == 0 &&
	   strncmp((char *)c->inmsg + c->ptr - 4, "\r\n\r\n", 4) == 0) {

	    /* remove the trailing \r\n\r\n so the string is NUL terminated */
	    c->inmsg[c->ptr - 4] = '\0';

	    c->flags |= HTTP_REPLY;

	    cs = handle_http_tcp(c);
	    if (cs == NULL) {
		c->flags |= WAITING_CLOSE;
		c->flags &= ~WAITING_READ;
		break;
	    }
	} else {
	    memcpy(&dlen, c->inmsg, sizeof(dlen));
	    dlen = ntohl(dlen);

	    if (dlen > MAX_PACKET_SIZE) {
		c->flags |= WAITING_CLOSE;
		c->flags &= ~WAITING_READ;
		return;
	    }
	    if (dlen > c->ptr - sizeof(dlen)) {
		break;
	    }

	    cs = emalloc(sizeof(*cs));
	    cs->c = c;
	    cs->in.data = emalloc(dlen);
	    memcpy(cs->in.data, c->inmsg + sizeof(dlen), dlen);
	    cs->in.length = dlen;

	    c->ptr -= sizeof(dlen) + dlen;
	    memmove(c->inmsg,
		    c->inmsg + sizeof(dlen) + dlen,
		    c->ptr);
	}

	c->calls++;

	if ((c->flags & UNIX_SOCKET) != 0) {
	    if (update_client_creds(c))
		_heim_ipc_create_cred(c->unixrights.uid, c->unixrights.gid,
				      c->unixrights.pid, -1, &cs->cred);
	}

	c->callback(c->userctx, &cs->in,
		    cs->cred, socket_complete,
		    (heim_sipc_call)cs);
    }
}

static void
handle_write(struct client *c)
{
    ssize_t len;

    len = write(c->fd, c->outmsg, c->olen);
    if (len <= 0) {
	c->flags |= WAITING_CLOSE;
	c->flags &= ~(WAITING_WRITE);
    } else if (c->olen != (size_t)len) {
	memmove(&c->outmsg[0], &c->outmsg[len], c->olen - len);
	c->olen -= len;
    } else {
	c->olen = 0;
	free(c->outmsg);
	c->outmsg = NULL;
	c->flags &= ~(WAITING_WRITE);
    }
}


#ifndef HAVE_GCD

static void
process_loop(void)
{
    struct pollfd *fds;
    unsigned n;
    unsigned num_fds;

    while(num_clients > 0) {

	fds = malloc(num_clients * sizeof(fds[0]));
	if(fds == NULL)
	    abort();

	num_fds = num_clients;

	for (n = 0 ; n < num_fds; n++) {
	    fds[n].fd = clients[n]->fd;
	    fds[n].events = 0;
	    if (clients[n]->flags & WAITING_READ)
		fds[n].events |= POLLIN;
	    if (clients[n]->flags & WAITING_WRITE)
		fds[n].events |= POLLOUT;

	    fds[n].revents = 0;
	}

	poll(fds, num_fds, -1);

	for (n = 0 ; n < num_fds; n++) {
	    if (clients[n] == NULL)
		continue;
	    if (fds[n].revents & POLLERR) {
		clients[n]->flags |= WAITING_CLOSE;
		continue;
	    }

	    if (fds[n].revents & POLLIN)
		handle_read(clients[n]);
	    if (fds[n].revents & POLLOUT)
		handle_write(clients[n]);
	}

	n = 0;
	while (n < num_clients) {
	    struct client *c = clients[n];
	    if (maybe_close(c)) {
		if (n < num_clients - 1)
		    clients[n] = clients[num_clients - 1];
		num_clients--;
	    } else
		n++;
	}

	free(fds);
    }
}

#endif

static int
socket_release(heim_sipc ctx)
{
    struct client *c = ctx->mech;
    c->flags |= WAITING_CLOSE;
    return 0;
}

int
heim_sipc_stream_listener(int fd, int type,
			  heim_ipc_callback callback,
			  void *user, heim_sipc *ctx)
{
    heim_sipc ct = calloc(1, sizeof(*ct));
    struct client *c;

    if ((type & HEIM_SIPC_TYPE_IPC) && (type & (HEIM_SIPC_TYPE_UINT32|HEIM_SIPC_TYPE_HTTP)))
	return EINVAL;

    switch (type) {
    case HEIM_SIPC_TYPE_IPC:
	c = add_new_socket(fd, LISTEN_SOCKET|WAITING_READ|INCLUDE_ERROR_CODE, callback, user);
	break;
    case HEIM_SIPC_TYPE_UINT32:
	c = add_new_socket(fd, LISTEN_SOCKET|WAITING_READ, callback, user);
	break;
    case HEIM_SIPC_TYPE_HTTP:
    case HEIM_SIPC_TYPE_UINT32|HEIM_SIPC_TYPE_HTTP:
	c = add_new_socket(fd, LISTEN_SOCKET|WAITING_READ|ALLOW_HTTP, callback, user);
	break;
    default:
	free(ct);
	return EINVAL;
    }

    ct->mech = c;
    ct->release = socket_release;

    c->unixrights.uid = (uid_t) -1;
    c->unixrights.gid = (gid_t) -1;
    c->unixrights.pid = (pid_t) 0;

    *ctx = ct;
    return 0;
}

int
heim_sipc_service_unix(const char *service,
		       heim_ipc_callback callback,
		       void *user, heim_sipc *ctx)
{
    struct sockaddr_un un;
    int fd, ret;

    un.sun_family = AF_UNIX;

    snprintf(un.sun_path, sizeof(un.sun_path),
	     "/var/run/.heim_%s-socket", service);
    fd = socket(AF_UNIX, SOCK_STREAM, 0);
    if (fd < 0)
	return errno;

    socket_set_reuseaddr(fd, 1);
#ifdef LOCAL_CREDS
    {
	int one = 1;
	setsockopt(fd, 0, LOCAL_CREDS, (void *)&one, sizeof(one));
    }
#endif

    unlink(un.sun_path);

    if (bind(fd, (struct sockaddr *)&un, sizeof(un)) < 0) {
	close(fd);
	return errno;
    }

    if (listen(fd, SOMAXCONN) < 0) {
	close(fd);
	return errno;
    }

    chmod(un.sun_path, 0666);

    ret = heim_sipc_stream_listener(fd, HEIM_SIPC_TYPE_IPC,
				    callback, user, ctx);
    if (ret == 0) {
	struct client *c = (*ctx)->mech;
	c->flags |= UNIX_SOCKET;
    }

    return ret;
}

/**
 * Set the idle timeout value

 * The timeout event handler is triggered recurrently every idle
 * period `t'. The default action is rather draconian and just calls
 * exit(0), so you might want to change this to something more
 * graceful using heim_sipc_set_timeout_handler().
 */

void
heim_sipc_timeout(time_t t)
{
#ifdef HAVE_GCD
    static dispatch_once_t timeoutonce;
    init_globals();
    dispatch_sync(timerq, ^{
	    timeoutvalue = t;
	    set_timer();
	});
    dispatch_once(&timeoutonce, ^{  dispatch_resume(timer); });
#else
    abort();
#endif
}

/**
 * Set the timeout event handler
 *
 * Replaces the default idle timeout action.
 */

void
heim_sipc_set_timeout_handler(void (*func)(void))
{
#ifdef HAVE_GCD
    init_globals();
    dispatch_sync(timerq, ^{ timer_ev = func; });
#else
    abort();
#endif
}


void
heim_sipc_free_context(heim_sipc ctx)
{
    (ctx->release)(ctx);
}

void
heim_ipc_main(void)
{
#ifdef HAVE_GCD
    dispatch_main();
#else
    process_loop();
#endif
}