/*        $Id: netproc.c,v 1.22 2019/02/01 10:16:04 benno Exp $ */
/*
 * Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
 *
 * Permission to use, copy, modify, and 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 THE AUTHORS DISCLAIM ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS 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.
 */

#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef __VMS
#include <tls.h>
#else
#include "wcme_config.h"
#include "libtls/tls.h"
#endif

#include "http.h"
#include "extern.h"
#ifndef WCME_IDIOM
#include "parse.h"
#endif

#define RETRY_DELAY 5
#define RETRY_MAX 10

/*
 * Buffer used when collecting the results of a CURL transfer.
 */
struct        buf {
        char        *buf; /* binary buffer */
        size_t         sz; /* length of buffer */
};

/*
 * Used for CURL communications.
 */
struct        conn {
        const char          *na; /* nonce authority */
        int                   fd; /* acctproc handle */
        int                   dfd; /* dnsproc handle */
        struct buf           buf; /* transfer buffer */
};

/*
 * If something goes wrong (or we're tracing output), we dump the
 * current transfer's data as a debug message.
 * Make sure that print all non-printable characters as question marks
 * so that we don't spam the console.
 * Also, consolidate white-space.
 * This of course will ruin string literals, but the intent here is just
 * to show the message, not to replicate it.
 */
static void
buf_dump(const struct buf *buf)
{
        size_t         i;
        int         j;
        char        *nbuf;

        if (buf->sz == 0)
                return;
        if ((nbuf = malloc(buf->sz)) == NULL)
                err(EXIT_FAILURE, "malloc");

        for (j = 0, i = 0; i < buf->sz; i++)
                if (isspace((int)buf->buf[i])) {
                        nbuf[j++] = ' ';
                        while (isspace((int)buf->buf[i]))
                                i++;
                        i--;
                } else
                        nbuf[j++] = isprint((int)buf->buf[i]) ?
                            buf->buf[i] : '?';
#ifndef __VMS
			nbuf[j++] = isprint((int)buf->buf[i]) ?
			    buf->buf[i] : '?';
        dodbg("transfer buffer: [%.*s] (%zu bytes)", j, nbuf, buf->sz);
#else
			nbuf[j++] = isascii((int)buf->buf[i]) &&
			            isprint((int)buf->buf[i]) ?
			    buf->buf[i] : '?';
        dodbg("transfer buffer: [%.*s] (%u bytes)", j, nbuf, buf->sz);
#endif
        free(nbuf);
}

/*
 * Extract the domain and port from a URL.
 * The url must be formatted as schema://address[/stuff].
 * This returns NULL on failure.
 */
static char *
url2host(const char *host, short *port, char **path)
{
        char        *url, *ep;

        /* We only understand HTTP and HTTPS. */
        if (strncmp(host, "https://", 8) == 0) {
                *port = 443;
                if ((url = strdup(host + 8)) == NULL) {
                        warn("strdup");
                        return NULL;
                }
        } else if (strncmp(host, "http://", 7) == 0) {
                *port = 80;
                if ((url = strdup(host + 7)) == NULL) {
                        warn("strdup");
                        return NULL;
                }
        } else {
                warnx("%s: unknown schema", host);
                return NULL;
        }

        /* Terminate path part. */
        if ((ep = strchr(url, '/')) != NULL) {
                *path = strdup(ep);
                *ep = '\0';
        } else
                *path = strdup("");

        if (*path == NULL) {
                warn("strdup");
                free(url);
                return NULL;
        }

        return url;
}

/*
 * Contact dnsproc and resolve a host.
 * Place the answers in "v" and return the number of answers, which can
 * be at most MAX_SERVERS_DNS.
 * Return <0 on failure.
 */
static ssize_t
urlresolve(int fd, const char *host, struct source *v)
{
        char                *addr;
        size_t                 i, sz;
        long                 lval;

        if (writeop(fd, COMM_DNS, DNS_LOOKUP) <= 0)
                return -1;
        else if (writestr(fd, COMM_DNSQ, host) <= 0)
                return -1;
        else if ((lval = readop(fd, COMM_DNSLEN)) < 0)
                return -1;

        sz = lval;
        assert(sz <= MAX_SERVERS_DNS);

        for (i = 0; i < sz; i++) {
                memset(&v[i], 0, sizeof(struct source));
                if ((lval = readop(fd, COMM_DNSF)) < 0)
                        goto err;
                else if (lval != 4 && lval != 6)
                        goto err;
                else if ((addr = readstr(fd, COMM_DNSA)) == NULL)
                        goto err;
                v[i].family = lval;
                v[i].ip = addr;
        }

        return sz;
err:
        for (i = 0; i < sz; i++)
                free(v[i].ip);
        return -1;
}

/*
 * Send a "regular" HTTP GET message to "addr" and stuff the response
 * into the connection buffer.
 * Return the HTTP error code or <0 on failure.
 */
static long
nreq(struct conn *c, const char *addr)
{
        struct httpget        *g;
        struct source         src[MAX_SERVERS_DNS];
        struct httphead *st;
        char                *host, *path;
        short                 port;
        size_t                 srcsz;
        ssize_t                 ssz;
        long                 code;
        int                 redirects = 0;

        if ((host = url2host(addr, &port, &path)) == NULL)
                return -1;

again:
        if ((ssz = urlresolve(c->dfd, host, src)) < 0) {
                free(host);
                free(path);
                return -1;
        }
        srcsz = ssz;

        g = http_get(src, srcsz, host, port, path, NULL, 0);
        free(host);
        free(path);
        if (g == NULL)
                return -1;

        switch (g->code) {
        case 301:
        case 302:
        case 303:
        case 307:
        case 308:
                redirects++;
                if (redirects > 3) {
                        warnx("too many redirects");
                        http_get_free(g);
                        return -1;
                }

                if ((st = http_head_get("Location", g->head, g->headsz)) ==
                    NULL) {
                        warnx("redirect without location header");
                        return -1;
                }

                dodbg("Location: %s", st->val);
                host = url2host(st->val, &port, &path);
                http_get_free(g);
                if (host == NULL)
                        return -1;
                goto again;
                break;
        default:
                code = g->code;
                break;
        }

        /* Copy the body part into our buffer. */
        free(c->buf.buf);
        c->buf.sz = g->bodypartsz;
        c->buf.buf = malloc(c->buf.sz);
        if (c->buf.buf == NULL) {
                warn("malloc");
                code = -1;
        } else
                memcpy(c->buf.buf, g->bodypart, c->buf.sz);
        http_get_free(g);
        return code;
}

/*
 * Create and send a signed communication to the ACME server.
 * Stuff the response into the communication buffer.
 * Return <0 on failure on the HTTP error code otherwise.
 */
static long
sreq(struct conn *c, const char *addr, const char *req)
{
        struct httpget        *g;
        struct source         src[MAX_SERVERS_DNS];
        char                *host, *path, *nonce, *reqsn;
        short                 port;
        struct httphead        *h;
        ssize_t                 ssz;
        long                 code;

        if ((host = url2host(c->na, &port, &path)) == NULL)
                return -1;

        if ((ssz = urlresolve(c->dfd, host, src)) < 0) {
                free(host);
                free(path);
                return -1;
        }

        g = http_get(src, (size_t)ssz, host, port, path, NULL, 0);
        free(host);
        free(path);
        if (g == NULL)
                return -1;

        h = http_head_get("Replay-Nonce", g->head, g->headsz);
        if (h == NULL) {
                warnx("%s: no replay nonce", c->na);
                http_get_free(g);
                return -1;
        } else if ((nonce = strdup(h->val)) == NULL) {
                warn("strdup");
                http_get_free(g);
                return -1;
        }
        http_get_free(g);

        /*
         * Send the nonce and request payload to the acctproc.
         * This will create the proper JSON object we need.
         */
        if (writeop(c->fd, COMM_ACCT, ACCT_SIGN) <= 0) {
                free(nonce);
                return -1;
        } else if (writestr(c->fd, COMM_PAY, req) <= 0) {
                free(nonce);
                return -1;
        } else if (writestr(c->fd, COMM_NONCE, nonce) <= 0) {
                free(nonce);
                return -1;
        }
        free(nonce);

        /* Now read back the signed payload. */
        if ((reqsn = readstr(c->fd, COMM_REQ)) == NULL)
                return -1;

        /* Now send the signed payload to the CA. */
        if ((host = url2host(addr, &port, &path)) == NULL) {
                free(reqsn);
                return -1;
        } else if ((ssz = urlresolve(c->dfd, host, src)) < 0) {
                free(host);
                free(path);
                free(reqsn);
                return -1;
        }

        g = http_get(src, (size_t)ssz, host, port, path, reqsn, strlen(reqsn));

        free(host);
        free(path);
        free(reqsn);
        if (g == NULL)
                return -1;

        /* Stuff response into parse buffer. */
        code = g->code;

        free(c->buf.buf);
        c->buf.sz = g->bodypartsz;
        c->buf.buf = malloc(c->buf.sz);
        if (c->buf.buf == NULL) {
                warn("malloc");
                code = -1;
        } else
                memcpy(c->buf.buf, g->bodypart, c->buf.sz);
        http_get_free(g);
        return code;
}

/*
 * Send to the CA that we want to authorise a new account.
 * This only happens once for a new account key.
 * Returns non-zero on success.
 */
static int
donewreg(struct conn *c, const struct capaths *p)
{
        int                 rc = 0;
        char                *req;
        long                 lc;

        dodbg("%s: new-reg", p->newreg);

        if ((req = json_fmt_newreg(p->agreement)) == NULL)
                warnx("json_fmt_newreg");
        else if ((lc = sreq(c, p->newreg, req)) < 0)
                warnx("%s: bad comm", p->newreg);
        else if (lc != 200 && lc != 201)
                warnx("%s: bad HTTP: %ld", p->newreg, lc);
        else if (c->buf.buf == NULL || c->buf.sz == 0)
                warnx("%s: empty response", p->newreg);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        free(req);
        return rc;
}

/*
 * Request a challenge for the given domain name.
 * This must be called for each name "alt".
 * On non-zero exit, fills in "chng" with the challenge.
 */
static int
dochngreq(struct conn *c, const char *alt, struct chng *chng,
    const struct capaths *p)
{
        int                 rc = 0;
        char                *req;
        long                 lc;
        struct jsmnn        *j = NULL;

        dodbg("%s: req-auth: %s", p->newauthz, alt);

        if ((req = json_fmt_newauthz(alt)) == NULL)
                warnx("json_fmt_newauthz");
        else if ((lc = sreq(c, p->newauthz, req)) < 0)
                warnx("%s: bad comm", p->newauthz);
        else if (lc != 200 && lc != 201)
                warnx("%s: bad HTTP: %ld", p->newauthz, lc);
        else if ((j = json_parse(c->buf.buf, c->buf.sz)) == NULL)
                warnx("%s: bad JSON object", p->newauthz);
        else if (!json_parse_challenge(j, chng))
                warnx("%s: bad challenge", p->newauthz);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        json_free(j);
        free(req);
        return rc;
}

/*
 * Tell the CA that a challenge response is in place.
 */
static int
dochngresp(struct conn *c, const struct chng *chng, const char *th)
{
        int         rc = 0;
        long         lc;
        char        *req;

        dodbg("%s: challenge", chng->uri);

        if ((req = json_fmt_challenge(chng->token, th)) == NULL)
                warnx("json_fmt_challenge");
        else if ((lc = sreq(c, chng->uri, req)) < 0)
                warnx("%s: bad comm", chng->uri);
        else if (lc != 200 && lc != 201 && lc != 202)
                warnx("%s: bad HTTP: %ld", chng->uri, lc);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        free(req);
        return rc;
}

/*
 * Check with the CA whether a challenge has been processed.
 * Note: we'll only do this a limited number of times, and pause for a
 * time between checks, but this happens in the caller.
 */
static int
dochngcheck(struct conn *c, struct chng *chng)
{
        enum chngstatus         cc;
        long                 lc;
        struct jsmnn        *j;

        dodbg("%s: status", chng->uri);

        if ((lc = nreq(c, chng->uri)) < 0) {
                warnx("%s: bad comm", chng->uri);
                return 0;
        } else if (lc != 200 && lc != 201 && lc != 202) {
                warnx("%s: bad HTTP: %ld", chng->uri, lc);
                buf_dump(&c->buf);
                return 0;
        } else if ((j = json_parse(c->buf.buf, c->buf.sz)) == NULL) {
                warnx("%s: bad JSON object", chng->uri);
                buf_dump(&c->buf);
                return 0;
        } else if ((cc = json_parse_response(j)) == -1) {
                warnx("%s: bad response", chng->uri);
                buf_dump(&c->buf);
                json_free(j);
                return 0;
        } else if (cc > 0)
                chng->status = CHNG_VALID;

        json_free(j);
        return 1;
}

static int
dorevoke(struct conn *c, const char *addr, const char *cert)
{
        char                *req;
        int                 rc = 0;
        long                 lc = 0;

        dodbg("%s: revocation", addr);

        if ((req = json_fmt_revokecert(cert)) == NULL)
                warnx("json_fmt_revokecert");
        else if ((lc = sreq(c, addr, req)) < 0)
                warnx("%s: bad comm", addr);
        else if (lc != 200 && lc != 201 && lc != 409)
                warnx("%s: bad HTTP: %ld", addr, lc);
        else
                rc = 1;

        if (lc == 409)
                warnx("%s: already revoked", addr);

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        free(req);
        return rc;
}

/*
 * Submit our certificate to the CA.
 * This, upon success, will return the signed CA.
 */
static int
docert(struct conn *c, const char *addr, const char *cert)
{
        char        *req;
        int         rc = 0;
        long         lc;

        dodbg("%s: certificate", addr);

        if ((req = json_fmt_newcert(cert)) == NULL)
                warnx("json_fmt_newcert");
        else if ((lc = sreq(c, addr, req)) < 0)
                warnx("%s: bad comm", addr);
        else if (lc != 200 && lc != 201)
                warnx("%s: bad HTTP: %ld", addr, lc);
        else if (c->buf.sz == 0 || c->buf.buf == NULL)
                warnx("%s: empty response", addr);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        free(req);
        return rc;
}

/*
 * Look up directories from the certificate authority.
 */
static int
dodirs(struct conn *c, const char *addr, struct capaths *paths)
{
        struct jsmnn        *j = NULL;
        long                 lc;
        int                 rc = 0;

        dodbg("%s: directories", addr);

        if ((lc = nreq(c, addr)) < 0)
                warnx("%s: bad comm", addr);
        else if (lc != 200 && lc != 201)
                warnx("%s: bad HTTP: %ld", addr, lc);
        else if ((j = json_parse(c->buf.buf, c->buf.sz)) == NULL)
                warnx("json_parse");
        else if (!json_parse_capaths(j, paths))
                warnx("%s: bad CA paths", addr);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        json_free(j);
        return rc;
}

/*
 * Request the full chain certificate.
 */
static int
dofullchain(struct conn *c, const char *addr)
{
        int         rc = 0;
        long         lc;

        dodbg("%s: full chain", addr);

        if ((lc = nreq(c, addr)) < 0)
                warnx("%s: bad comm", addr);
        else if (lc != 200 && lc != 201)
                warnx("%s: bad HTTP: %ld", addr, lc);
        else
                rc = 1;

        if (rc == 0 || verbose > 1)
                buf_dump(&c->buf);
        return rc;
}

/*
 * Communicate with the ACME server.
 * We need the certificate we want to upload and our account key information.
 */
int
netproc(int kfd, int afd, int Cfd, int cfd, int dfd, int rfd,
    int newacct, int revocate, struct authority_c *authority,
    const char *const *alts, size_t altsz)
{
        int                 rc = 0;
        size_t                 i, done = 0;
        char                *cert = NULL, *thumb = NULL, *url = NULL;
        struct conn         c;
        struct capaths         paths;
        struct chng        *chngs = NULL;
        long                 lval;

        memset(&paths, 0, sizeof(struct capaths));
        memset(&c, 0, sizeof(struct conn));

        if (unveil(tls_default_ca_cert_file(), "r") == -1) {
                warn("unveil");
                goto out;
        }

        if (pledge("stdio inet rpath", NULL) == -1) {
                warn("pledge");
                goto out;
        }

        if (http_init() == -1) {
                warn("http_init");
                goto out;
        }

        if (pledge("stdio inet", NULL) == -1) {
                warn("pledge");
                goto out;
        }

#ifdef WCME_IDIOM
        /* /REGISTER and /CHECK=API take no site name are handled here */
	if (!altsz || newacct)
        {
           if (newacct)
           {
              /* need the account process to be up and ready */
              if ((lval = readop(afd, COMM_ACCT_STAT)) == 0) {
                 rc = 1;
                 goto out;
              } else if (lval != ACCT_READY) {
                 warnx("unknown operation from acctproc");
                 goto out;
              }
           }

           chngs = calloc(altsz, sizeof(struct chng));
           if (chngs == NULL) {
              warn("calloc");
              goto out;
           }

           c.dfd = dfd;
           c.fd = afd;
           c.na = authority->api;

           if (!dodirs(&c, c.na, &paths))
              goto out;

           if (newacct)
           {
              /* if new, register HERE with the CA */
              if (!donewreg(&c, &paths))
                 goto out;
           }
           else
           {
              /* without a domain we're just querying the CA */
              fprintf (stdout,
"%%WCME-I-CA, %s\n\
  newauthz: %s\n\
   newcert: %s\n\
    newreg: %s\n\
revokecert: %s\n\
 agreement: %s\n",
                       authority->api,
                       paths.newauthz,
                       paths.newcert,
                       paths.newreg,
                       paths.revokecert,
                       paths.agreement);
           }
           rc = 1;
           goto out;
        }
#endif /* WCME_IDIOM */

        /*
         * Wait until the acctproc, keyproc, and revokeproc have started up and
         * are ready to serve us data.
         * Then check whether revokeproc indicates that the certificate on file
         * (if any) can be updated.
         */
        if ((lval = readop(afd, COMM_ACCT_STAT)) == 0) {
                rc = 1;
                goto out;
        } else if (lval != ACCT_READY) {
                warnx("unknown operation from acctproc");
                goto out;
        }

        if ((lval = readop(kfd, COMM_KEY_STAT)) == 0) {
                rc = 1;
                goto out;
        } else if (lval != KEY_READY) {
                warnx("unknown operation from keyproc");
                goto out;
        }

        if ((lval = readop(rfd, COMM_REVOKE_RESP)) == 0) {
                rc = 1;
                goto out;
        } else if (lval != REVOKE_EXP && lval != REVOKE_OK) {
                warnx("unknown operation from revokeproc");
                goto out;
        }

        /* If our certificate is up-to-date, return now. */
        if (lval == REVOKE_OK) {
                rc = 1;
                goto out;
        }

        /* Allocate main state. */
        chngs = calloc(altsz, sizeof(struct chng));
        if (chngs == NULL) {
                warn("calloc");
                goto out;
        }

        c.dfd = dfd;
        c.fd = afd;
        c.na = authority->api;

        /*
         * Look up the API urls of the ACME server.
         */
        if (!dodirs(&c, c.na, &paths))
                goto out;

        /*
         * If we're meant to revoke, then wait for revokeproc to send us
         * the certificate (if it's found at all).
         * Following that, submit the request to the CA then notify the
         * certproc, which will in turn notify the fileproc.
         */
        if (revocate) {
                if ((cert = readstr(rfd, COMM_CSR)) == NULL)
                        goto out;
                if (!dorevoke(&c, paths.revokecert, cert))
                        goto out;
                else if (writeop(cfd, COMM_CSR_OP, CERT_REVOKE) > 0)
                        rc = 1;
                goto out;
        }

        /* If new, register with the CA server. */

#ifndef WCME_IDIOM
        /* if registering new account */
	if (newacct && !donewreg(&c, &paths))
           goto out;
#endif /* WCME_IDIOM */

        /* Pre-authorise all domains with CA server. */
        for (i = 0; i < altsz; i++)
                if (!dochngreq(&c, alts[i], &chngs[i], &paths))
                        goto out;

        /*
         * We now have our challenges.
         * We need to ask the acctproc for the thumbprint.
         * We'll combine this to the challenge to create our response,
         * which will be orchestrated by the chngproc.
         */
        if (writeop(afd, COMM_ACCT, ACCT_THUMBPRINT) <= 0)
                goto out;
        else if ((thumb = readstr(afd, COMM_THUMB)) == NULL)
                goto out;

        /* We'll now ask chngproc to build the challenge. */
        for (i = 0; i < altsz; i++) {
                if (writeop(Cfd, COMM_CHNG_OP, CHNG_SYN) <= 0)
                        goto out;
                else if (writestr(Cfd, COMM_THUMB, thumb) <= 0)
                        goto out;
                else if (writestr(Cfd, COMM_TOK, chngs[i].token) <= 0)
                        goto out;

                /* Read that the challenge has been made. */
                if (readop(Cfd, COMM_CHNG_ACK) != CHNG_ACK)
                        goto out;

                /* Write to the CA that it's ready. */
                if (!dochngresp(&c, &chngs[i], thumb))
                        goto out;
        }

        /*
         * We now wait on the ACME server for each domain.
         * Connect to the server (assume it's the same server) once
         * every five seconds.
         */
        for (;;) {
                for (i = 0; i < altsz; i++) {
                        doddbg("%s: done %lu, altsz %lu, i %lu, status %d",
                            __func__, done, altsz, i, chngs[i].status);

                        if (chngs[i].status == CHNG_VALID)
                                continue;

                        if (chngs[i].retry++ >= RETRY_MAX) {
                                warnx("%s: too many tries", chngs[i].uri);
                                goto out;
                        }

                        sleep(RETRY_DELAY);
                        if (dochngcheck(&c, &chngs[i])) {
                                if (chngs[i].status == CHNG_VALID)
                                        done++;
                                continue;
                        } else
                                goto out;
                }

                if (done == altsz)
                        break;
        }

        /*
         * Write our acknowledgement that the challenges are over.
         * The challenge process will remove all of the files.
         */
        if (writeop(Cfd, COMM_CHNG_OP, CHNG_STOP) <= 0)
                goto out;

        /* Wait to receive the certificate itself. */
        if ((cert = readstr(kfd, COMM_CERT)) == NULL)
                goto out;

        /*
         * Otherwise, submit the CA for signing, download the signed
         * copy, and ship that into the certificate process for copying.
         */
        if (!docert(&c, paths.newcert, cert))
                goto out;
        else if (writeop(cfd, COMM_CSR_OP, CERT_UPDATE) <= 0)
                goto out;
        else if (writebuf(cfd, COMM_CSR, c.buf.buf, c.buf.sz) <= 0)
                goto out;

        /*
         * Read back the issuer from the certproc.
         * Then contact the issuer to get the certificate chain.
         * Write this chain directly back to the certproc.
         */
        if ((url = readstr(cfd, COMM_ISSUER)) == NULL)
                goto out;
        else if (!dofullchain(&c, url))
                goto out;
        else if (writebuf(cfd, COMM_CHAIN, c.buf.buf, c.buf.sz) <= 0)
                goto out;

        rc = 1;
out:
        close(cfd);
        close(kfd);
        close(afd);
        close(Cfd);
        close(dfd);
        close(rfd);
        free(cert);
        free(url);
        free(thumb);
        free(c.buf.buf);
        if (chngs != NULL)
                for (i = 0; i < altsz; i++)
                        json_free_challenge(&chngs[i]);
        free(chngs);
        json_free_capaths(&paths);
        return rc;
}