httpd.c

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/*
 * Copyright (C) 2006-2008, 2010-2015  Internet Systems Consortium, Inc. ("ISC")
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

/*! \file */

#include <config.h>

#include <isc/buffer.h>
#include <isc/httpd.h>
#include <isc/mem.h>
#include <isc/socket.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/time.h>
#include <isc/util.h>

#include <string.h>

/*%
 * TODO:
 *
 *  o  Put in better checks to make certain things are passed in correctly.
 *     This includes a magic number for externally-visible structures,
 *     checking for NULL-ness before dereferencing, etc.
 *  o  Make the URL processing external functions which will fill-in a buffer
 *     structure we provide, or return an error and we will render a generic
 *     page and close the client.
 */

#define MSHUTTINGDOWN(cm) ((cm->flags & ISC_HTTPDMGR_FLAGSHUTTINGDOWN) != 0)
#define MSETSHUTTINGDOWN(cm) (cm->flags |= ISC_HTTPDMGR_FLAGSHUTTINGDOWN)

#ifdef DEBUG_HTTPD
#define ENTER(x) do { fprintf(stderr, "ENTER %s\n", (x)); } while (0)
#define EXIT(x) do { fprintf(stderr, "EXIT %s\n", (x)); } while (0)
#define NOTICE(x) do { fprintf(stderr, "NOTICE %s\n", (x)); } while (0)
#else
#define ENTER(x) do { } while(0)
#define EXIT(x) do { } while(0)
#define NOTICE(x) do { } while(0)
#endif

#define HTTP_RECVLEN                    1024
#define HTTP_SENDGROW                   1024
#define HTTP_SEND_MAXLEN                10240

#define HTTPD_CLOSE             0x0001 /* Got a Connection: close header */
#define HTTPD_FOUNDHOST         0x0002 /* Got a Host: header */

/*% http client */
struct isc_httpd {
        isc_httpdmgr_t         *mgr;            /*%< our parent */
        ISC_LINK(isc_httpd_t)   link;
        unsigned int            state;
        isc_socket_t            *sock;

        /*%
         * Received data state.
         */
        char                    recvbuf[HTTP_RECVLEN]; /*%< receive buffer */
        isc_uint32_t            recvlen;        /*%< length recv'd */
        char                   *headers;        /*%< set in process_request() */
        unsigned int            method;
        char                   *url;
        char                   *querystring;
        char                   *protocol;

        /*
         * Flags on the httpd client.
         */
        int                     flags;

        /*%
         * Transmit data state.
         *
         * This is the data buffer we will transmit.
         *
         * This free function pointer is filled in by the rendering function
         * we call.  The free function is called after the data is transmitted
         * to the client.
         *
         * The bufflist is the list of buffers we are currently transmitting.
         * The headerdata is where we render our headers to.  If we run out of
         * space when rendering a header, we will change the size of our
         * buffer.  We will not free it until we are finished, and will
         * allocate an additional HTTP_SENDGROW bytes per header space grow.
         *
         * We currently use two buffers total, one for the headers (which
         * we manage) and another for the client to fill in (which it manages,
         * it provides the space for it, etc) -- we will pass that buffer
         * structure back to the caller, who is responsible for managing the
         * space it may have allocated as backing store for it.  This second
         * buffer is bodybuffer, and we only allocate the buffer itself, not
         * the backing store.
         */
        isc_bufferlist_t        bufflist;
        char                   *headerdata; /*%< send header buf */
        unsigned int            headerlen;  /*%< current header buffer size */
        isc_buffer_t            headerbuffer;

        const char             *mimetype;
        unsigned int            retcode;
        const char             *retmsg;
        isc_buffer_t            bodybuffer;
        isc_httpdfree_t        *freecb;
        void                   *freecb_arg;
};

/*% lightweight socket manager for httpd output */
struct isc_httpdmgr {
        isc_mem_t              *mctx;
        isc_socket_t           *sock;           /*%< listening socket */
        isc_task_t             *task;           /*%< owning task */
        isc_timermgr_t         *timermgr;

        isc_httpdclientok_t    *client_ok;      /*%< client validator */
        isc_httpdondestroy_t   *ondestroy;      /*%< cleanup callback */
        void                   *cb_arg;         /*%< argument for the above */

        unsigned int            flags;
        ISC_LIST(isc_httpd_t)   running;        /*%< running clients */

        isc_mutex_t             lock;

        ISC_LIST(isc_httpdurl_t) urls;          /*%< urls we manage */
        isc_httpdaction_t      *render_404;
        isc_httpdaction_t      *render_500;
};

/*%
 * HTTP methods.
 */
#define ISC_HTTPD_METHODUNKNOWN 0
#define ISC_HTTPD_METHODGET     1
#define ISC_HTTPD_METHODPOST    2

/*%
 * Client states.
 *
 * _IDLE        The client is not doing anything at all.  This state should
 *              only occur just after creation, and just before being
 *              destroyed.
 *
 * _RECV        The client is waiting for data after issuing a socket recv().
 *
 * _RECVDONE    Data has been received, and is being processed.
 *
 * _SEND        All data for a response has completed, and a reply was
 *              sent via a socket send() call.
 *
 * _SENDDONE    Send is completed.
 *
 * Badly formatted state table:
 *
 *      IDLE -> RECV when client has a recv() queued.
 *
 *      RECV -> RECVDONE when recvdone event received.
 *
 *      RECVDONE -> SEND if the data for a reply is at hand.
 *
 *      SEND -> RECV when a senddone event was received.
 *
 *      At any time -> RECV on error.  If RECV fails, the client will
 *      self-destroy, closing the socket and freeing memory.
 */
#define ISC_HTTPD_STATEIDLE     0
#define ISC_HTTPD_STATERECV     1
#define ISC_HTTPD_STATERECVDONE 2
#define ISC_HTTPD_STATESEND     3
#define ISC_HTTPD_STATESENDDONE 4

#define ISC_HTTPD_ISRECV(c)     ((c)->state == ISC_HTTPD_STATERECV)
#define ISC_HTTPD_ISRECVDONE(c) ((c)->state == ISC_HTTPD_STATERECVDONE)
#define ISC_HTTPD_ISSEND(c)     ((c)->state == ISC_HTTPD_STATESEND)
#define ISC_HTTPD_ISSENDDONE(c) ((c)->state == ISC_HTTPD_STATESENDDONE)

/*%
 * Overall magic test that means we're not idle.
 */
#define ISC_HTTPD_SETRECV(c)    ((c)->state = ISC_HTTPD_STATERECV)
#define ISC_HTTPD_SETRECVDONE(c)        ((c)->state = ISC_HTTPD_STATERECVDONE)
#define ISC_HTTPD_SETSEND(c)    ((c)->state = ISC_HTTPD_STATESEND)
#define ISC_HTTPD_SETSENDDONE(c)        ((c)->state = ISC_HTTPD_STATESENDDONE)

static void isc_httpd_accept(isc_task_t *, isc_event_t *);
static void isc_httpd_recvdone(isc_task_t *, isc_event_t *);
static void isc_httpd_senddone(isc_task_t *, isc_event_t *);
static void destroy_client(isc_httpd_t **);
static isc_result_t process_request(isc_httpd_t *, int);
static void httpdmgr_destroy(isc_httpdmgr_t *);
static isc_result_t grow_headerspace(isc_httpd_t *);
static void reset_client(isc_httpd_t *httpd);

static isc_httpdaction_t render_404;
static isc_httpdaction_t render_500;

static void
destroy_client(isc_httpd_t **httpdp) {
        isc_httpd_t *httpd = *httpdp;
        isc_httpdmgr_t *httpdmgr = httpd->mgr;

        *httpdp = NULL;

        LOCK(&httpdmgr->lock);

        isc_socket_detach(&httpd->sock);
        ISC_LIST_UNLINK(httpdmgr->running, httpd, link);

        if (httpd->headerlen > 0)
                isc_mem_put(httpdmgr->mctx, httpd->headerdata,
                            httpd->headerlen);

        isc_mem_put(httpdmgr->mctx, httpd, sizeof(isc_httpd_t));

        UNLOCK(&httpdmgr->lock);

        httpdmgr_destroy(httpdmgr);
}

isc_result_t
isc_httpdmgr_create(isc_mem_t *mctx, isc_socket_t *sock, isc_task_t *task,
                    isc_httpdclientok_t *client_ok,
                    isc_httpdondestroy_t *ondestroy, void *cb_arg,
                    isc_timermgr_t *tmgr, isc_httpdmgr_t **httpdp)
{
        isc_result_t result;
        isc_httpdmgr_t *httpd;

        REQUIRE(mctx != NULL);
        REQUIRE(sock != NULL);
        REQUIRE(task != NULL);
        REQUIRE(tmgr != NULL);
        REQUIRE(httpdp != NULL && *httpdp == NULL);

        httpd = isc_mem_get(mctx, sizeof(isc_httpdmgr_t));
        if (httpd == NULL)
                return (ISC_R_NOMEMORY);

        result = isc_mutex_init(&httpd->lock);
        if (result != ISC_R_SUCCESS) {
                isc_mem_put(mctx, httpd, sizeof(isc_httpdmgr_t));
                return (result);
        }
        httpd->mctx = NULL;
        isc_mem_attach(mctx, &httpd->mctx);
        httpd->sock = NULL;
        isc_socket_attach(sock, &httpd->sock);
        httpd->task = NULL;
        isc_task_attach(task, &httpd->task);
        httpd->timermgr = tmgr; /* XXXMLG no attach function? */
        httpd->client_ok = client_ok;
        httpd->ondestroy = ondestroy;
        httpd->cb_arg = cb_arg;

        ISC_LIST_INIT(httpd->running);
        ISC_LIST_INIT(httpd->urls);

        /* XXXMLG ignore errors on isc_socket_listen() */
        result = isc_socket_listen(sock, SOMAXCONN);
        if (result != ISC_R_SUCCESS) {
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "isc_socket_listen() failed: %s",
                                 isc_result_totext(result));
                goto cleanup;
        }

        (void)isc_socket_filter(sock, "httpready");

        result = isc_socket_accept(sock, task, isc_httpd_accept, httpd);
        if (result != ISC_R_SUCCESS)
                goto cleanup;

        httpd->render_404 = render_404;
        httpd->render_500 = render_500;

        *httpdp = httpd;
        return (ISC_R_SUCCESS);

  cleanup:
        isc_task_detach(&httpd->task);
        isc_socket_detach(&httpd->sock);
        isc_mem_detach(&httpd->mctx);
        (void)isc_mutex_destroy(&httpd->lock);
        isc_mem_put(mctx, httpd, sizeof(isc_httpdmgr_t));
        return (result);
}

static void
httpdmgr_destroy(isc_httpdmgr_t *httpdmgr) {
        isc_mem_t *mctx;
        isc_httpdurl_t *url;

        ENTER("httpdmgr_destroy");

        LOCK(&httpdmgr->lock);

        if (!MSHUTTINGDOWN(httpdmgr)) {
                NOTICE("httpdmgr_destroy not shutting down yet");
                UNLOCK(&httpdmgr->lock);
                return;
        }

        /*
         * If all clients are not shut down, don't do anything yet.
         */
        if (!ISC_LIST_EMPTY(httpdmgr->running)) {
                NOTICE("httpdmgr_destroy clients still active");
                UNLOCK(&httpdmgr->lock);
                return;
        }

        NOTICE("httpdmgr_destroy detaching socket, task, and timermgr");

        isc_socket_detach(&httpdmgr->sock);
        isc_task_detach(&httpdmgr->task);
        httpdmgr->timermgr = NULL;

        /*
         * Clear out the list of all actions we know about.  Just free the
         * memory.
         */
        url = ISC_LIST_HEAD(httpdmgr->urls);
        while (url != NULL) {
                isc_mem_free(httpdmgr->mctx, url->url);
                ISC_LIST_UNLINK(httpdmgr->urls, url, link);
                isc_mem_put(httpdmgr->mctx, url, sizeof(isc_httpdurl_t));
                url = ISC_LIST_HEAD(httpdmgr->urls);
        }

        UNLOCK(&httpdmgr->lock);
        (void)isc_mutex_destroy(&httpdmgr->lock);

        if (httpdmgr->ondestroy != NULL)
                (httpdmgr->ondestroy)(httpdmgr->cb_arg);

        mctx = httpdmgr->mctx;
        isc_mem_putanddetach(&mctx, httpdmgr, sizeof(isc_httpdmgr_t));

        EXIT("httpdmgr_destroy");
}

#define LENGTHOK(s) (httpd->recvbuf - (s) < (int)httpd->recvlen)
#define BUFLENOK(s) (httpd->recvbuf - (s) < HTTP_RECVLEN)

static isc_result_t
process_request(isc_httpd_t *httpd, int length) {
        char *s;
        char *p;
        int delim;

        ENTER("request");

        httpd->recvlen += length;

        httpd->recvbuf[httpd->recvlen] = 0;
        httpd->headers = NULL;

        /*
         * If we don't find a blank line in our buffer, return that we need
         * more data.
         */
        s = strstr(httpd->recvbuf, "\r\n\r\n");
        delim = 1;
        if (s == NULL) {
                s = strstr(httpd->recvbuf, "\n\n");
                delim = 2;
        }
        if (s == NULL)
                return (ISC_R_NOTFOUND);

        /*
         * Determine if this is a POST or GET method.  Any other values will
         * cause an error to be returned.
         */
        if (strncmp(httpd->recvbuf, "GET ", 4) == 0) {
                httpd->method = ISC_HTTPD_METHODGET;
                p = httpd->recvbuf + 4;
        } else if (strncmp(httpd->recvbuf, "POST ", 5) == 0) {
                httpd->method = ISC_HTTPD_METHODPOST;
                p = httpd->recvbuf + 5;
        } else {
                return (ISC_R_RANGE);
        }

        /*
         * From now on, p is the start of our buffer.
         */

        /*
         * Extract the URL.
         */
        s = p;
        while (LENGTHOK(s) && BUFLENOK(s) &&
               (*s != '\n' && *s != '\r' && *s != '\0' && *s != ' '))
                s++;
        if (!LENGTHOK(s))
                return (ISC_R_NOTFOUND);
        if (!BUFLENOK(s))
                return (ISC_R_NOMEMORY);
        *s = 0;

        /*
         * Make the URL relative.
         */
        if ((strncmp(p, "http:/", 6) == 0)
            || (strncmp(p, "https:/", 7) == 0)) {
                /* Skip first / */
                while (*p != '/' && *p != 0)
                        p++;
                if (*p == 0)
                        return (ISC_R_RANGE);
                p++;
                /* Skip second / */
                while (*p != '/' && *p != 0)
                        p++;
                if (*p == 0)
                        return (ISC_R_RANGE);
                p++;
                /* Find third / */
                while (*p != '/' && *p != 0)
                        p++;
                if (*p == 0) {
                        p--;
                        *p = '/';
                }
        }

        httpd->url = p;
        p = s + delim;
        s = p;

        /*
         * Now, see if there is a ? mark in the URL.  If so, this is
         * part of the query string, and we will split it from the URL.
         */
        httpd->querystring = strchr(httpd->url, '?');
        if (httpd->querystring != NULL) {
                *(httpd->querystring) = 0;
                httpd->querystring++;
        }

        /*
         * Extract the HTTP/1.X protocol.  We will bounce on anything but
         * HTTP/1.1 for now.
         */
        while (LENGTHOK(s) && BUFLENOK(s) &&
               (*s != '\n' && *s != '\r' && *s != '\0'))
                s++;
        if (!LENGTHOK(s))
                return (ISC_R_NOTFOUND);
        if (!BUFLENOK(s))
                return (ISC_R_NOMEMORY);
        *s = 0;
        if ((strncmp(p, "HTTP/1.0", 8) != 0)
            && (strncmp(p, "HTTP/1.1", 8) != 0))
                return (ISC_R_RANGE);
        httpd->protocol = p;
        p = s + 1;
        s = p;

        httpd->headers = s;

        if (strstr(s, "Connection: close") != NULL)
                httpd->flags |= HTTPD_CLOSE;

        if (strstr(s, "Host: ") != NULL)
                httpd->flags |= HTTPD_FOUNDHOST;

        /*
         * Standards compliance hooks here.
         */
        if (strcmp(httpd->protocol, "HTTP/1.1") == 0
            && ((httpd->flags & HTTPD_FOUNDHOST) == 0))
                return (ISC_R_RANGE);

        EXIT("request");

        return (ISC_R_SUCCESS);
}

static void
isc_httpd_accept(isc_task_t *task, isc_event_t *ev) {
        isc_result_t result;
        isc_httpdmgr_t *httpdmgr = ev->ev_arg;
        isc_httpd_t *httpd;
        isc_region_t r;
        isc_socket_newconnev_t *nev = (isc_socket_newconnev_t *)ev;
        isc_sockaddr_t peeraddr;

        ENTER("accept");

        LOCK(&httpdmgr->lock);
        if (MSHUTTINGDOWN(httpdmgr)) {
                NOTICE("accept shutting down, goto out");
                goto out;
        }

        if (nev->result == ISC_R_CANCELED) {
                NOTICE("accept canceled, goto out");
                goto out;
        }

        if (nev->result != ISC_R_SUCCESS) {
                /* XXXMLG log failure */
                NOTICE("accept returned failure, goto requeue");
                goto requeue;
        }

        (void)isc_socket_getpeername(nev->newsocket, &peeraddr);
        if (httpdmgr->client_ok != NULL &&
            !(httpdmgr->client_ok)(&peeraddr, httpdmgr->cb_arg)) {
                isc_socket_detach(&nev->newsocket);
                goto requeue;
        }

        httpd = isc_mem_get(httpdmgr->mctx, sizeof(isc_httpd_t));
        if (httpd == NULL) {
                /* XXXMLG log failure */
                NOTICE("accept failed to allocate memory, goto requeue");
                isc_socket_detach(&nev->newsocket);
                goto requeue;
        }

        httpd->mgr = httpdmgr;
        ISC_LINK_INIT(httpd, link);
        ISC_LIST_APPEND(httpdmgr->running, httpd, link);
        ISC_HTTPD_SETRECV(httpd);
        httpd->sock = nev->newsocket;
        isc_socket_setname(httpd->sock, "httpd", NULL);
        httpd->flags = 0;

        /*
         * Initialize the buffer for our headers.
         */
        httpd->headerdata = isc_mem_get(httpdmgr->mctx, HTTP_SENDGROW);
        if (httpd->headerdata == NULL) {
                isc_mem_put(httpdmgr->mctx, httpd, sizeof(isc_httpd_t));
                isc_socket_detach(&nev->newsocket);
                goto requeue;
        }
        httpd->headerlen = HTTP_SENDGROW;
        isc_buffer_init(&httpd->headerbuffer, httpd->headerdata,
                        httpd->headerlen);

        ISC_LIST_INIT(httpd->bufflist);

        isc_buffer_initnull(&httpd->bodybuffer);
        reset_client(httpd);

        r.base = (unsigned char *)httpd->recvbuf;
        r.length = HTTP_RECVLEN - 1;
        result = isc_socket_recv(httpd->sock, &r, 1, task, isc_httpd_recvdone,
                                 httpd);
        /* FIXME!!! */
        POST(result);
        NOTICE("accept queued recv on socket");

 requeue:
        result = isc_socket_accept(httpdmgr->sock, task, isc_httpd_accept,
                                   httpdmgr);
        if (result != ISC_R_SUCCESS) {
                /* XXXMLG what to do?  Log failure... */
                NOTICE("accept could not reaccept due to failure");
        }

 out:
        UNLOCK(&httpdmgr->lock);

        httpdmgr_destroy(httpdmgr);

        isc_event_free(&ev);

        EXIT("accept");
}

static isc_result_t
render_404(const char *url, isc_httpdurl_t *urlinfo,
           const char *querystring, const char *headers, void *arg,
           unsigned int *retcode, const char **retmsg,
           const char **mimetype, isc_buffer_t *b,
           isc_httpdfree_t **freecb, void **freecb_args)
{
        static char msg[] = "No such URL.";

        UNUSED(url);
        UNUSED(urlinfo);
        UNUSED(querystring);
        UNUSED(headers);
        UNUSED(arg);

        *retcode = 404;
        *retmsg = "No such URL";
        *mimetype = "text/plain";
        isc_buffer_reinit(b, msg, strlen(msg));
        isc_buffer_add(b, strlen(msg));
        *freecb = NULL;
        *freecb_args = NULL;

        return (ISC_R_SUCCESS);
}

static isc_result_t
render_500(const char *url, isc_httpdurl_t *urlinfo,
           const char *querystring, const char *headers, void *arg,
           unsigned int *retcode, const char **retmsg,
           const char **mimetype, isc_buffer_t *b,
           isc_httpdfree_t **freecb, void **freecb_args)
{
        static char msg[] = "Internal server failure.";

        UNUSED(url);
        UNUSED(urlinfo);
        UNUSED(querystring);
        UNUSED(headers);
        UNUSED(arg);

        *retcode = 500;
        *retmsg = "Internal server failure";
        *mimetype = "text/plain";
        isc_buffer_reinit(b, msg, strlen(msg));
        isc_buffer_add(b, strlen(msg));
        *freecb = NULL;
        *freecb_args = NULL;

        return (ISC_R_SUCCESS);
}

static void
isc_httpd_recvdone(isc_task_t *task, isc_event_t *ev) {
        isc_region_t r;
        isc_result_t result;
        isc_httpd_t *httpd = ev->ev_arg;
        isc_socketevent_t *sev = (isc_socketevent_t *)ev;
        isc_httpdurl_t *url;
        isc_time_t now;
        char datebuf[ISC_FORMATHTTPTIMESTAMP_SIZE];

        ENTER("recv");

        INSIST(ISC_HTTPD_ISRECV(httpd));

        if (sev->result != ISC_R_SUCCESS) {
                NOTICE("recv destroying client");
                destroy_client(&httpd);
                goto out;
        }

        result = process_request(httpd, sev->n);
        if (result == ISC_R_NOTFOUND) {
                if (httpd->recvlen >= HTTP_RECVLEN - 1) {
                        destroy_client(&httpd);
                        goto out;
                }
                r.base = (unsigned char *)httpd->recvbuf + httpd->recvlen;
                r.length = HTTP_RECVLEN - httpd->recvlen - 1;
                /* check return code? */
                (void)isc_socket_recv(httpd->sock, &r, 1, task,
                                      isc_httpd_recvdone, httpd);
                goto out;
        } else if (result != ISC_R_SUCCESS) {
                destroy_client(&httpd);
                goto out;
        }

        ISC_HTTPD_SETSEND(httpd);

        /*
         * XXXMLG Call function here.  Provide an add-header function
         * which will append the common headers to a response we generate.
         */
        isc_buffer_initnull(&httpd->bodybuffer);
        isc_time_now(&now);
        isc_time_formathttptimestamp(&now, datebuf, sizeof(datebuf));
        url = ISC_LIST_HEAD(httpd->mgr->urls);
        while (url != NULL) {
                if (strcmp(httpd->url, url->url) == 0)
                        break;
                url = ISC_LIST_NEXT(url, link);
        }
        if (url == NULL)
                result = httpd->mgr->render_404(httpd->url, NULL,
                                                httpd->querystring,
                                                NULL, NULL,
                                                &httpd->retcode,
                                                &httpd->retmsg,
                                                &httpd->mimetype,
                                                &httpd->bodybuffer,
                                                &httpd->freecb,
                                                &httpd->freecb_arg);
        else
                result = url->action(httpd->url, url,
                                     httpd->querystring,
                                     httpd->headers,
                                     url->action_arg,
                                     &httpd->retcode, &httpd->retmsg,
                                     &httpd->mimetype, &httpd->bodybuffer,
                                     &httpd->freecb, &httpd->freecb_arg);
        if (result != ISC_R_SUCCESS) {
                result = httpd->mgr->render_500(httpd->url, url,
                                                httpd->querystring,
                                                NULL, NULL,
                                                &httpd->retcode,
                                                &httpd->retmsg,
                                                &httpd->mimetype,
                                                &httpd->bodybuffer,
                                                &httpd->freecb,
                                                &httpd->freecb_arg);
                RUNTIME_CHECK(result == ISC_R_SUCCESS);
        }

        isc_httpd_response(httpd);
        isc_httpd_addheader(httpd, "Content-Type", httpd->mimetype);
        isc_httpd_addheader(httpd, "Date", datebuf);
        isc_httpd_addheader(httpd, "Expires", datebuf);

        if (url != NULL && url->isstatic) {
                char loadbuf[ISC_FORMATHTTPTIMESTAMP_SIZE];
                isc_time_formathttptimestamp(&url->loadtime,
                                             loadbuf, sizeof(loadbuf));
                isc_httpd_addheader(httpd, "Last-Modified", loadbuf);
                isc_httpd_addheader(httpd, "Cache-Control: public", NULL);
        } else {
                isc_httpd_addheader(httpd, "Last-Modified", datebuf);
                isc_httpd_addheader(httpd, "Pragma: no-cache", NULL);
                isc_httpd_addheader(httpd, "Cache-Control: no-cache", NULL);
        }

        isc_httpd_addheader(httpd, "Server: libisc", NULL);
        isc_httpd_addheaderuint(httpd, "Content-Length",
                                isc_buffer_usedlength(&httpd->bodybuffer));
        isc_httpd_endheaders(httpd);  /* done */

        ISC_LIST_APPEND(httpd->bufflist, &httpd->headerbuffer, link);
        /*
         * Link the data buffer into our send queue, should we have any data
         * rendered into it.  If no data is present, we won't do anything
         * with the buffer.
         */
        if (isc_buffer_length(&httpd->bodybuffer) > 0)
                ISC_LIST_APPEND(httpd->bufflist, &httpd->bodybuffer, link);

        /* check return code? */
        (void)isc_socket_sendv(httpd->sock, &httpd->bufflist, task,
                               isc_httpd_senddone, httpd);

 out:
        isc_event_free(&ev);
        EXIT("recv");
}

void
isc_httpdmgr_shutdown(isc_httpdmgr_t **httpdmgrp) {
        isc_httpdmgr_t *httpdmgr;
        isc_httpd_t *httpd;
        httpdmgr = *httpdmgrp;
        *httpdmgrp = NULL;

        ENTER("isc_httpdmgr_shutdown");

        LOCK(&httpdmgr->lock);

        MSETSHUTTINGDOWN(httpdmgr);

        isc_socket_cancel(httpdmgr->sock, httpdmgr->task, ISC_SOCKCANCEL_ALL);

        httpd = ISC_LIST_HEAD(httpdmgr->running);
        while (httpd != NULL) {
                isc_socket_cancel(httpd->sock, httpdmgr->task,
                                  ISC_SOCKCANCEL_ALL);
                httpd = ISC_LIST_NEXT(httpd, link);
        }

        UNLOCK(&httpdmgr->lock);

        EXIT("isc_httpdmgr_shutdown");
}

static isc_result_t
grow_headerspace(isc_httpd_t *httpd) {
        char *newspace;
        unsigned int newlen;
        isc_region_t r;

        newlen = httpd->headerlen + HTTP_SENDGROW;
        if (newlen > HTTP_SEND_MAXLEN)
                return (ISC_R_NOSPACE);

        newspace = isc_mem_get(httpd->mgr->mctx, newlen);
        if (newspace == NULL)
                return (ISC_R_NOMEMORY);
        isc_buffer_region(&httpd->headerbuffer, &r);
        isc_buffer_reinit(&httpd->headerbuffer, newspace, newlen);

        isc_mem_put(httpd->mgr->mctx, r.base, r.length);

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_httpd_response(isc_httpd_t *httpd) {
        isc_result_t result;
        unsigned int needlen;

        needlen = strlen(httpd->protocol) + 1; /* protocol + space */
        needlen += 3 + 1;  /* room for response code, always 3 bytes */
        needlen += strlen(httpd->retmsg) + 2;  /* return msg + CRLF */

        while (isc_buffer_availablelength(&httpd->headerbuffer) < needlen) {
                result = grow_headerspace(httpd);
                if (result != ISC_R_SUCCESS)
                        return (result);
        }

        sprintf(isc_buffer_used(&httpd->headerbuffer), "%s %03d %s\r\n",
                httpd->protocol, httpd->retcode, httpd->retmsg);
        isc_buffer_add(&httpd->headerbuffer, needlen);

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_httpd_addheader(isc_httpd_t *httpd, const char *name,
                    const char *val)
{
        isc_result_t result;
        unsigned int needlen;

        needlen = strlen(name); /* name itself */
        if (val != NULL)
                needlen += 2 + strlen(val); /* :<space> and val */
        needlen += 2; /* CRLF */

        while (isc_buffer_availablelength(&httpd->headerbuffer) < needlen) {
                result = grow_headerspace(httpd);
                if (result != ISC_R_SUCCESS)
                        return (result);
        }

        if (val != NULL)
                sprintf(isc_buffer_used(&httpd->headerbuffer),
                        "%s: %s\r\n", name, val);
        else
                sprintf(isc_buffer_used(&httpd->headerbuffer),
                        "%s\r\n", name);

        isc_buffer_add(&httpd->headerbuffer, needlen);

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_httpd_endheaders(isc_httpd_t *httpd) {
        isc_result_t result;

        while (isc_buffer_availablelength(&httpd->headerbuffer) < 2) {
                result = grow_headerspace(httpd);
                if (result != ISC_R_SUCCESS)
                        return (result);
        }

        sprintf(isc_buffer_used(&httpd->headerbuffer), "\r\n");
        isc_buffer_add(&httpd->headerbuffer, 2);

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_httpd_addheaderuint(isc_httpd_t *httpd, const char *name, int val) {
        isc_result_t result;
        unsigned int needlen;
        char buf[sizeof "18446744073709551616"];

        sprintf(buf, "%d", val);

        needlen = strlen(name); /* name itself */
        needlen += 2 + strlen(buf); /* :<space> and val */
        needlen += 2; /* CRLF */

        while (isc_buffer_availablelength(&httpd->headerbuffer) < needlen) {
                result = grow_headerspace(httpd);
                if (result != ISC_R_SUCCESS)
                        return (result);
        }

        sprintf(isc_buffer_used(&httpd->headerbuffer),
                "%s: %s\r\n", name, buf);

        isc_buffer_add(&httpd->headerbuffer, needlen);

        return (ISC_R_SUCCESS);
}

static void
isc_httpd_senddone(isc_task_t *task, isc_event_t *ev) {
        isc_httpd_t *httpd = ev->ev_arg;
        isc_region_t r;
        isc_socketevent_t *sev = (isc_socketevent_t *)ev;

        ENTER("senddone");
        INSIST(ISC_HTTPD_ISSEND(httpd));

        /*
         * First, unlink our header buffer from the socket's bufflist.  This
         * is sort of an evil hack, since we know our buffer will be there,
         * and we know it's address, so we can just remove it directly.
         */
        NOTICE("senddone unlinked header");
        ISC_LIST_UNLINK(sev->bufferlist, &httpd->headerbuffer, link);

        /*
         * We will always want to clean up our receive buffer, even if we
         * got an error on send or we are shutting down.
         *
         * We will pass in the buffer only if there is data in it.  If
         * there is no data, we will pass in a NULL.
         */
        if (httpd->freecb != NULL) {
                isc_buffer_t *b = NULL;
                if (isc_buffer_length(&httpd->bodybuffer) > 0) {
                        b = &httpd->bodybuffer;
                        httpd->freecb(b, httpd->freecb_arg);
                }
                NOTICE("senddone free callback performed");
        }
        if (ISC_LINK_LINKED(&httpd->bodybuffer, link)) {
                ISC_LIST_UNLINK(sev->bufferlist, &httpd->bodybuffer, link);
                NOTICE("senddone body buffer unlinked");
        }

        if (sev->result != ISC_R_SUCCESS) {
                destroy_client(&httpd);
                goto out;
        }

        if ((httpd->flags & HTTPD_CLOSE) != 0) {
                destroy_client(&httpd);
                goto out;
        }

        ISC_HTTPD_SETRECV(httpd);

        NOTICE("senddone restarting recv on socket");

        reset_client(httpd);

        r.base = (unsigned char *)httpd->recvbuf;
        r.length = HTTP_RECVLEN - 1;
        /* check return code? */
        (void)isc_socket_recv(httpd->sock, &r, 1, task,
                              isc_httpd_recvdone, httpd);

out:
        isc_event_free(&ev);
        EXIT("senddone");
}

static void
reset_client(isc_httpd_t *httpd) {
        /*
         * Catch errors here.  We MUST be in RECV mode, and we MUST NOT have
         * any outstanding buffers.  If we have buffers, we have a leak.
         */
        INSIST(ISC_HTTPD_ISRECV(httpd));
        INSIST(!ISC_LINK_LINKED(&httpd->headerbuffer, link));
        INSIST(!ISC_LINK_LINKED(&httpd->bodybuffer, link));

        httpd->recvbuf[0] = 0;
        httpd->recvlen = 0;
        httpd->headers = NULL;
        httpd->method = ISC_HTTPD_METHODUNKNOWN;
        httpd->url = NULL;
        httpd->querystring = NULL;
        httpd->protocol = NULL;
        httpd->flags = 0;

        isc_buffer_clear(&httpd->headerbuffer);
        isc_buffer_invalidate(&httpd->bodybuffer);
}

isc_result_t
isc_httpdmgr_addurl(isc_httpdmgr_t *httpdmgr, const char *url,
                    isc_httpdaction_t *func, void *arg)
{
        return (isc_httpdmgr_addurl2(httpdmgr, url, ISC_FALSE, func, arg));
}

isc_result_t
isc_httpdmgr_addurl2(isc_httpdmgr_t *httpdmgr, const char *url,
                     isc_boolean_t isstatic,
                     isc_httpdaction_t *func, void *arg)
{
        isc_httpdurl_t *item;

        if (url == NULL) {
                httpdmgr->render_404 = func;
                return (ISC_R_SUCCESS);
        }

        item = isc_mem_get(httpdmgr->mctx, sizeof(isc_httpdurl_t));
        if (item == NULL)
                return (ISC_R_NOMEMORY);

        item->url = isc_mem_strdup(httpdmgr->mctx, url);
        if (item->url == NULL) {
                isc_mem_put(httpdmgr->mctx, item, sizeof(isc_httpdurl_t));
                return (ISC_R_NOMEMORY);
        }

        item->action = func;
        item->action_arg = arg;
        item->isstatic = isstatic;
        isc_time_now(&item->loadtime);

        ISC_LINK_INIT(item, link);
        ISC_LIST_APPEND(httpdmgr->urls, item, link);

        return (ISC_R_SUCCESS);
}

---