/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1998-2016 Dag-Erling Smørgrav
 * Copyright (c) 2013 Michael Gmelin <freebsd@grem.de>
 * 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
 *    in this position and unchanged.
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/uio.h>

#include <netinet/in.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <netdb.h>
#include <paths.h>
#include <poll.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#ifdef WITH_SSL
#include <openssl/x509v3.h>
#endif

#include "fetch.h"
#include "common.h"


/*** Local data **************************************************************/

/*
 * Error messages for resolver errors
 */
static struct fetcherr netdb_errlist[] = {
#ifdef EAI_ADDRFAMILY
        { EAI_ADDRFAMILY, FETCH_RESOLV, "Address family for host not supported" },
#endif
#ifdef EAI_NODATA
        { EAI_NODATA,   FETCH_RESOLV,   "No address for host" },
#endif
        { EAI_AGAIN,    FETCH_TEMP,     "Transient resolver failure" },
        { EAI_FAIL,     FETCH_RESOLV,   "Non-recoverable resolver failure" },
        { EAI_NONAME,   FETCH_RESOLV,   "Host does not resolve" },
        { -1,           FETCH_UNKNOWN,  "Unknown resolver error" }
};

/*
 * SOCKS5 error enumerations
 */
enum SOCKS5_ERR {
/* Protocol errors */
        SOCKS5_ERR_SELECTION,
        SOCKS5_ERR_READ_METHOD,
        SOCKS5_ERR_VER5_ONLY,
        SOCKS5_ERR_NOMETHODS,
        SOCKS5_ERR_NOTIMPLEMENTED,
        SOCKS5_ERR_HOSTNAME_SIZE,
        SOCKS5_ERR_REQUEST,
        SOCKS5_ERR_REPLY,
        SOCKS5_ERR_NON_VER5_RESP,
        SOCKS5_ERR_GENERAL,
        SOCKS5_ERR_NOT_ALLOWED,
        SOCKS5_ERR_NET_UNREACHABLE,
        SOCKS5_ERR_HOST_UNREACHABLE,
        SOCKS5_ERR_CONN_REFUSED,
        SOCKS5_ERR_TTL_EXPIRED,
        SOCKS5_ERR_COM_UNSUPPORTED,
        SOCKS5_ERR_ADDR_UNSUPPORTED,
        SOCKS5_ERR_UNSPECIFIED,
/* Configuration errors */
        SOCKS5_ERR_BAD_HOST,
        SOCKS5_ERR_BAD_PROXY_FORMAT,
        SOCKS5_ERR_BAD_PORT
};

/*
 * Error messages for SOCKS5 errors
 */
static struct fetcherr socks5_errlist[] = {
/* SOCKS5 protocol errors */
        { SOCKS5_ERR_SELECTION,         FETCH_ABORT,    "SOCKS5: Failed to send selection method" },
        { SOCKS5_ERR_READ_METHOD,       FETCH_ABORT,    "SOCKS5: Failed to read method" },
        { SOCKS5_ERR_VER5_ONLY,         FETCH_PROTO,    "SOCKS5: Only version 5 is implemented" },
        { SOCKS5_ERR_NOMETHODS,         FETCH_PROTO,    "SOCKS5: No acceptable methods" },
        { SOCKS5_ERR_NOTIMPLEMENTED,    FETCH_PROTO,    "SOCKS5: Method currently not implemented" },
        { SOCKS5_ERR_HOSTNAME_SIZE,     FETCH_PROTO,    "SOCKS5: Hostname size is above 256 bytes" },
        { SOCKS5_ERR_REQUEST,           FETCH_PROTO,    "SOCKS5: Failed to request" },
        { SOCKS5_ERR_REPLY,             FETCH_PROTO,    "SOCKS5: Failed to receive reply" },
        { SOCKS5_ERR_NON_VER5_RESP,     FETCH_PROTO,    "SOCKS5: Server responded with a non-version 5 response" },
        { SOCKS5_ERR_GENERAL,           FETCH_ABORT,    "SOCKS5: General server failure" },
        { SOCKS5_ERR_NOT_ALLOWED,       FETCH_AUTH,     "SOCKS5: Connection not allowed by ruleset" },
        { SOCKS5_ERR_NET_UNREACHABLE,   FETCH_NETWORK,  "SOCKS5: Network unreachable" },
        { SOCKS5_ERR_HOST_UNREACHABLE,  FETCH_ABORT,    "SOCKS5: Host unreachable" },
        { SOCKS5_ERR_CONN_REFUSED,      FETCH_ABORT,    "SOCKS5: Connection refused" },
        { SOCKS5_ERR_TTL_EXPIRED,       FETCH_TIMEOUT,  "SOCKS5: TTL expired" },
        { SOCKS5_ERR_COM_UNSUPPORTED,   FETCH_PROTO,    "SOCKS5: Command not supported" },
        { SOCKS5_ERR_ADDR_UNSUPPORTED,  FETCH_ABORT,    "SOCKS5: Address type not supported" },
        { SOCKS5_ERR_UNSPECIFIED,       FETCH_UNKNOWN,  "SOCKS5: Unspecified error" },
/* Configuration error */
        { SOCKS5_ERR_BAD_HOST,          FETCH_ABORT,    "SOCKS5: Bad proxy host" },
        { SOCKS5_ERR_BAD_PROXY_FORMAT,  FETCH_ABORT,    "SOCKS5: Bad proxy format" },
        { SOCKS5_ERR_BAD_PORT,          FETCH_ABORT,    "SOCKS5: Bad port" }
};

/* End-of-Line */
static const char ENDL[2] = { '\r', '\n' };


/*** Error-reporting functions ***********************************************/

/*
 * Map error code to string
 */
static struct fetcherr *
fetch_finderr(struct fetcherr *p, int e)
{
        while (p->num != -1 && p->num != e)
                p++;
        return (p);
}

/*
 * Set error code
 */
void
fetch_seterr(struct fetcherr *p, int e)
{
        p = fetch_finderr(p, e);
        fetchLastErrCode = p->cat;
        snprintf(fetchLastErrString, MAXERRSTRING, "%s", p->string);
}

/*
 * Set error code according to errno
 */
void
fetch_syserr(void)
{
        switch (errno) {
        case 0:
                fetchLastErrCode = FETCH_OK;
                break;
        case EPERM:
        case EACCES:
        case EROFS:
        case EAUTH:
        case ENEEDAUTH:
                fetchLastErrCode = FETCH_AUTH;
                break;
        case ENOENT:
        case EISDIR: /* XXX */
                fetchLastErrCode = FETCH_UNAVAIL;
                break;
        case ENOMEM:
                fetchLastErrCode = FETCH_MEMORY;
                break;
        case EBUSY:
        case EAGAIN:
                fetchLastErrCode = FETCH_TEMP;
                break;
        case EEXIST:
                fetchLastErrCode = FETCH_EXISTS;
                break;
        case ENOSPC:
                fetchLastErrCode = FETCH_FULL;
                break;
        case EADDRINUSE:
        case EADDRNOTAVAIL:
        case ENETDOWN:
        case ENETUNREACH:
        case ENETRESET:
        case EHOSTUNREACH:
                fetchLastErrCode = FETCH_NETWORK;
                break;
        case ECONNABORTED:
        case ECONNRESET:
                fetchLastErrCode = FETCH_ABORT;
                break;
        case ETIMEDOUT:
                fetchLastErrCode = FETCH_TIMEOUT;
                break;
        case ECONNREFUSED:
        case EHOSTDOWN:
                fetchLastErrCode = FETCH_DOWN;
                break;
        default:
                fetchLastErrCode = FETCH_UNKNOWN;
        }
        snprintf(fetchLastErrString, MAXERRSTRING, "%s", strerror(errno));
}


/*
 * Emit status message
 */
void
fetch_info(const char *fmt, ...)
{
        va_list ap;
        int serrno = errno;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);
        fputc('\n', stderr);
        errno = serrno;
}
#define fetch_verbose(...)                                              \
        do { if (verbose) fetch_info(__VA_ARGS__); } while (0)


/*** Network-related utility functions ***************************************/

/*
 * Return the default port for a scheme
 */
int
fetch_default_port(const char *scheme)
{
        struct servent *se;

        if ((se = getservbyname(scheme, "tcp")) != NULL)
                return (ntohs(se->s_port));
        if (strcmp(scheme, SCHEME_FTP) == 0)
                return (FTP_DEFAULT_PORT);
        if (strcmp(scheme, SCHEME_HTTP) == 0)
                return (HTTP_DEFAULT_PORT);
        return (0);
}

/*
 * Return the default proxy port for a scheme
 */
int
fetch_default_proxy_port(const char *scheme)
{
        if (strcmp(scheme, SCHEME_FTP) == 0)
                return (FTP_DEFAULT_PROXY_PORT);
        if (strcmp(scheme, SCHEME_HTTP) == 0)
                return (HTTP_DEFAULT_PROXY_PORT);
        return (0);
}


/*
 * Create a connection for an existing descriptor.
 */
conn_t *
fetch_reopen(int sd)
{
        conn_t *conn;
        int flags;
        int opt = 1;

        /* allocate and fill connection structure */
        if ((conn = calloc(1, sizeof(*conn))) == NULL)
                return (NULL);
        flags = fcntl(sd, F_GETFD);
        if (flags != -1 && (flags & FD_CLOEXEC) == 0)
                (void)fcntl(sd, F_SETFD, flags | FD_CLOEXEC);
        flags = fcntl(sd, F_GETFL);
        if (flags != -1 && (flags & O_NONBLOCK) == 0)
                (void)fcntl(sd, F_SETFL, flags | O_NONBLOCK);
        (void)setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &opt, sizeof(opt));
        conn->sd = sd;
        ++conn->ref;
        return (conn);
}


/*
 * Bump a connection's reference count.
 */
conn_t *
fetch_ref(conn_t *conn)
{
        ++conn->ref;
        return (conn);
}


/*
 * Resolve an address
 */
struct addrinfo *
fetch_resolve(const char *addr, int port, int af)
{
        char hbuf[256], sbuf[8];
        struct addrinfo hints, *res;
        const char *hb, *he, *sep;
        const char *host, *service;
        int err, len;

        /* first, check for a bracketed IPv6 address */
        if (*addr == '[') {
                hb = addr + 1;
                if ((sep = strchr(hb, ']')) == NULL) {
                        errno = EINVAL;
                        goto syserr;
                }
                he = sep++;
        } else {
                hb = addr;
                sep = strchrnul(hb, ':');
                he = sep;
        }

        /* see if we need to copy the host name */
        if (*he != '\0') {
                len = snprintf(hbuf, sizeof(hbuf),
                    "%.*s", (int)(he - hb), hb);
                if (len < 0)
                        goto syserr;
                if (len >= (int)sizeof(hbuf)) {
                        errno = ENAMETOOLONG;
                        goto syserr;
                }
                host = hbuf;
        } else {
                host = hb;
        }

        /* was it followed by a service name? */
        if (*sep == '\0' && port != 0) {
                if (port < 1 || port > 65535) {
                        errno = EINVAL;
                        goto syserr;
                }
                if (snprintf(sbuf, sizeof(sbuf), "%d", port) < 0)
                        goto syserr;
                service = sbuf;
        } else if (*sep != '\0') {
                service = sep + 1;
        } else {
                service = NULL;
        }

        /* resolve */
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = af;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_ADDRCONFIG;
        if ((err = getaddrinfo(host, service, &hints, &res)) != 0) {
                netdb_seterr(err);
                return (NULL);
        }
        return (res);
syserr:
        fetch_syserr();
        return (NULL);
}


/*
 * Bind a socket to a specific local address
 */
int
fetch_bind(int sd, int af, const char *addr)
{
        struct addrinfo *cliai, *ai;
        int err;

        if ((cliai = fetch_resolve(addr, 0, af)) == NULL)
                return (-1);
        for (ai = cliai; ai != NULL; ai = ai->ai_next)
                if ((err = bind(sd, ai->ai_addr, ai->ai_addrlen)) == 0)
                        break;
        if (err != 0)
                fetch_syserr();
        freeaddrinfo(cliai);
        return (err == 0 ? 0 : -1);
}


/*
 * SOCKS5 connection initiation, based on RFC 1928
 * Default DNS resolution over SOCKS5
 */
int
fetch_socks5_init(conn_t *conn, const char *host, int port, int verbose)
{
        /*
         * Size is based on largest packet prefix (4 bytes) +
         * Largest FQDN (256) + one byte size (1) +
         * Port (2)
         */
        unsigned char buf[BUFF_SIZE];
        unsigned char *ptr;
        int ret = 1;

        fetch_verbose("Initializing SOCKS5 connection: %s:%d", host, port);

        /* Connection initialization */
        ptr = buf;
        *ptr++ = SOCKS_VERSION_5;
        *ptr++ = SOCKS_CONNECTION;
        *ptr++ = SOCKS_RSV;

        if (fetch_write(conn, buf, 3) != 3) {
                ret = SOCKS5_ERR_SELECTION;
                goto fail;
        }

        /* Verify response from SOCKS5 server */
        if (fetch_read(conn, buf, 2) != 2) {
                ret = SOCKS5_ERR_READ_METHOD;
                goto fail;
        }

        ptr = buf;
        if (ptr[0] != SOCKS_VERSION_5) {
                ret = SOCKS5_ERR_VER5_ONLY;
                goto fail;
        }
        if (ptr[1] == SOCKS_NOMETHODS) {
                ret = SOCKS5_ERR_NOMETHODS;
                goto fail;
        }
        else if (ptr[1] != SOCKS5_NOTIMPLEMENTED) {
                ret = SOCKS5_ERR_NOTIMPLEMENTED;
                goto fail;
        }

        /* Send Request */
        *ptr++ = SOCKS_VERSION_5;
        *ptr++ = SOCKS_CONNECTION;
        *ptr++ = SOCKS_RSV;
        /* Encode all targets as a hostname to avoid DNS leaks */
        *ptr++ = SOCKS_ATYP_DOMAINNAME;
        if (strlen(host) > FQDN_SIZE) {
                ret = SOCKS5_ERR_HOSTNAME_SIZE;
                goto fail;
        }
        *ptr++ = strlen(host);
        memcpy(ptr, host, strlen(host));
        ptr = ptr + strlen(host);

        port = htons(port);
        *ptr++ = port & 0x00ff;
        *ptr++ = (port & 0xff00) >> 8;

        if (fetch_write(conn, buf, ptr - buf) != ptr - buf) {
                ret = SOCKS5_ERR_REQUEST;
                goto fail;
        }

        /* BND.ADDR is variable length, read the largest on non-blocking socket */
        if (!fetch_read(conn, buf, BUFF_SIZE)) {
                ret = SOCKS5_ERR_REPLY;
                goto fail;
        }

        ptr = buf;
        if (*ptr++ != SOCKS_VERSION_5) {
                ret = SOCKS5_ERR_NON_VER5_RESP;
                goto fail;
        }

        switch (*ptr++) {
        case SOCKS_SUCCESS:
                break;
        case SOCKS_GENERAL_FAILURE:
                ret = SOCKS5_ERR_GENERAL;
                goto fail;
        case SOCKS_CONNECTION_NOT_ALLOWED:
                ret = SOCKS5_ERR_NOT_ALLOWED;
                goto fail;
        case SOCKS_NETWORK_UNREACHABLE:
                ret = SOCKS5_ERR_NET_UNREACHABLE;
                goto fail;
        case SOCKS_HOST_UNREACHABLE:
                ret = SOCKS5_ERR_HOST_UNREACHABLE;
                goto fail;
        case SOCKS_CONNECTION_REFUSED:
                ret = SOCKS5_ERR_CONN_REFUSED;
                goto fail;
        case SOCKS_TTL_EXPIRED:
                ret = SOCKS5_ERR_TTL_EXPIRED;
                goto fail;
        case SOCKS_COMMAND_NOT_SUPPORTED:
                ret = SOCKS5_ERR_COM_UNSUPPORTED;
                goto fail;
        case SOCKS_ADDRESS_NOT_SUPPORTED:
                ret = SOCKS5_ERR_ADDR_UNSUPPORTED;
                goto fail;
        default:
                ret = SOCKS5_ERR_UNSPECIFIED;
                goto fail;
        }

        return (ret);

fail:
        socks5_seterr(ret);
        return (0);
}

/*
 * Perform SOCKS5 initialization
 */
int
fetch_socks5_getenv(char **host, int *port)
{
        char *socks5env, *endptr, *ext;
        const char *portDelim;
        size_t slen;

        portDelim = ":";
        if ((socks5env = getenv("SOCKS5_PROXY")) == NULL || *socks5env == '\0') {
                *host = NULL;
                *port = -1;
                return (-1);
        }

        /*
         * IPv6 addresses begin and end in brackets.  Set the port delimiter
         * accordingly and search for it so we can do appropriate validation.
         */
        if (socks5env[0] == '[')
                portDelim = "]:";

        slen = strlen(socks5env);
        ext = strstr(socks5env, portDelim);
        if (socks5env[0] == '[') {
                if (socks5env[slen - 1] == ']') {
                        *host = strndup(socks5env, slen);
                } else if (ext != NULL) {
                        *host = strndup(socks5env, ext - socks5env + 1);
                } else {
                        socks5_seterr(SOCKS5_ERR_BAD_PROXY_FORMAT);
                        return (0);
                }
        } else {
                *host = strndup(socks5env, ext - socks5env);
        }

        if (*host == NULL)
                return (-1);
        if (ext == NULL) {
                *port = 1080; /* Default port as defined in RFC1928 */
        } else {
                ext += strlen(portDelim);
                errno = 0;
                *port = strtoimax(ext, (char **)&endptr, 10);
                if (*endptr != '\0' || errno != 0 || *port < 0 ||
                    *port > 65535) {
                        free(*host);
                        *host = NULL;
                        socks5_seterr(SOCKS5_ERR_BAD_PORT);
                        return (0);
                }
        }

        return (2);
}


/*
 * Establish a TCP connection to the specified port on the specified host.
 */
conn_t *
fetch_connect(const char *host, int port, int af, int verbose)
{
        struct addrinfo *cais = NULL, *sais = NULL, *cai, *sai;
        const char *bindaddr;
        conn_t *conn = NULL;
        int err = 0, sd = -1;
        char *sockshost;
        int socksport;

        DEBUGF("---> %s:%d\n", host, port);

        /*
         * Check if SOCKS5_PROXY env variable is set.  fetch_socks5_getenv
         * will either set sockshost = NULL or allocate memory in all cases.
         */
        sockshost = NULL;
        if (!fetch_socks5_getenv(&sockshost, &socksport))
                goto fail;

        /* Not using SOCKS5 proxy */
        if (sockshost == NULL) {
                /* resolve server address */
                fetch_verbose("resolving server address: %s:%d", host, port);
                if ((sais = fetch_resolve(host, port, af)) == NULL)
                        goto fail;

                /* resolve client address */
                bindaddr = getenv("FETCH_BIND_ADDRESS");
                if (bindaddr != NULL && *bindaddr != '\0') {
                        fetch_verbose("resolving client address: %s", bindaddr);
                        if ((cais = fetch_resolve(bindaddr, 0, af)) == NULL)
                                goto fail;
                }
        } else {
                /* resolve socks5 proxy address */
                fetch_verbose("resolving SOCKS5 server address: %s:%d",
                    sockshost, socksport);
                if ((sais = fetch_resolve(sockshost, socksport, af)) == NULL) {
                        socks5_seterr(SOCKS5_ERR_BAD_HOST);
                        goto fail;
                }
        }

        /* try each server address in turn */
        for (err = 0, sai = sais; sai != NULL; sai = sai->ai_next) {
                /* open socket */
                if ((sd = socket(sai->ai_family, SOCK_STREAM, 0)) < 0) {
                        err = -1;
                        if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
                                continue;
                        goto syserr;
                }
                /* attempt to bind to client address */
                for (err = 0, cai = cais; cai != NULL; cai = cai->ai_next) {
                        if (cai->ai_family != sai->ai_family)
                                continue;
                        if ((err = bind(sd, cai->ai_addr, cai->ai_addrlen)) == 0)
                                break;
                }
                if (err != 0) {
                        fetch_verbose("failed to bind to %s", bindaddr);
                        goto syserr;
                }
                /* attempt to connect to server address */
                while ((err = connect(sd, sai->ai_addr, sai->ai_addrlen)) < 0) {
                        if (errno == EINTR && fetchRestartCalls)
                                continue;
                        break;
                }
                /* success? */
                if (err == 0)
                        break;
                /* clean up before next attempt */
                close(sd);
                sd = -1;
        }
        if (err != 0) {
                if (verbose && sockshost == NULL) {
                        fetch_info("failed to connect to %s:%d", host, port);
                        goto syserr;
                } else if (sockshost != NULL) {
                        fetch_verbose("failed to connect to SOCKS5 server %s:%d",
                            sockshost, socksport);
                        socks5_seterr(SOCKS5_ERR_CONN_REFUSED);
                        goto fail;
                }
                goto syserr;
        }

        if ((conn = fetch_reopen(sd)) == NULL)
                goto syserr;

        if (sockshost)
                if (!fetch_socks5_init(conn, host, port, verbose))
                        goto fail;
        free(sockshost);
        if (cais != NULL)
                freeaddrinfo(cais);
        if (sais != NULL)
                freeaddrinfo(sais);
        return (conn);
syserr:
        fetch_syserr();
fail:
        free(sockshost);
        /* Fully close if it was opened; otherwise just don't leak the fd. */
        if (conn != NULL)
                fetch_close(conn);
        else if (sd >= 0)
                close(sd);
        if (cais != NULL)
                freeaddrinfo(cais);
        if (sais != NULL)
                freeaddrinfo(sais);
        return (NULL);
}

#ifdef WITH_SSL
/*
 * Convert characters A-Z to lowercase (intentionally avoid any locale
 * specific conversions).
 */
static char
fetch_ssl_tolower(char in)
{
        if (in >= 'A' && in <= 'Z')
                return (in + 32);
        else
                return (in);
}

/*
 * isalpha implementation that intentionally avoids any locale specific
 * conversions.
 */
static int
fetch_ssl_isalpha(char in)
{
        return ((in >= 'A' && in <= 'Z') || (in >= 'a' && in <= 'z'));
}

/*
 * Check if passed hostnames a and b are equal.
 */
static int
fetch_ssl_hname_equal(const char *a, size_t alen, const char *b,
    size_t blen)
{
        size_t i;

        if (alen != blen)
                return (0);
        for (i = 0; i < alen; ++i) {
                if (fetch_ssl_tolower(a[i]) != fetch_ssl_tolower(b[i]))
                        return (0);
        }
        return (1);
}

/*
 * Check if domain label is traditional, meaning that only A-Z, a-z, 0-9
 * and '-' (hyphen) are allowed. Hyphens have to be surrounded by alpha-
 * numeric characters. Double hyphens (like they're found in IDN a-labels
 * 'xn--') are not allowed. Empty labels are invalid.
 */
static int
fetch_ssl_is_trad_domain_label(const char *l, size_t len, int wcok)
{
        size_t i;

        if (!len || l[0] == '-' || l[len-1] == '-')
                return (0);
        for (i = 0; i < len; ++i) {
                if (!isdigit(l[i]) &&
                    !fetch_ssl_isalpha(l[i]) &&
                    !(l[i] == '*' && wcok) &&
                    !(l[i] == '-' && l[i - 1] != '-'))
                        return (0);
        }
        return (1);
}

/*
 * Check if host name consists only of numbers. This might indicate an IP
 * address, which is not a good idea for CN wildcard comparison.
 */
static int
fetch_ssl_hname_is_only_numbers(const char *hostname, size_t len)
{
        size_t i;

        for (i = 0; i < len; ++i) {
                if (!((hostname[i] >= '0' && hostname[i] <= '9') ||
                    hostname[i] == '.'))
                        return (0);
        }
        return (1);
}

/*
 * Check if the host name h passed matches the pattern passed in m which
 * is usually part of subjectAltName or CN of a certificate presented to
 * the client. This includes wildcard matching. The algorithm is based on
 * RFC6125, sections 6.4.3 and 7.2, which clarifies RFC2818 and RFC3280.
 */
static int
fetch_ssl_hname_match(const char *h, size_t hlen, const char *m,
    size_t mlen)
{
        int delta, hdotidx, mdot1idx, wcidx;
        const char *hdot, *mdot1, *mdot2;
        const char *wc; /* wildcard */

        if (!(h && *h && m && *m))
                return (0);
        if ((wc = strnstr(m, "*", mlen)) == NULL)
                return (fetch_ssl_hname_equal(h, hlen, m, mlen));
        wcidx = wc - m;
        /* hostname should not be just dots and numbers */
        if (fetch_ssl_hname_is_only_numbers(h, hlen))
                return (0);
        /* only one wildcard allowed in pattern */
        if (strnstr(wc + 1, "*", mlen - wcidx - 1) != NULL)
                return (0);
        /*
         * there must be at least two more domain labels and
         * wildcard has to be in the leftmost label (RFC6125)
         */
        mdot1 = strnstr(m, ".", mlen);
        if (mdot1 == NULL || mdot1 < wc || (mlen - (mdot1 - m)) < 4)
                return (0);
        mdot1idx = mdot1 - m;
        mdot2 = strnstr(mdot1 + 1, ".", mlen - mdot1idx - 1);
        if (mdot2 == NULL || (mlen - (mdot2 - m)) < 2)
                return (0);
        /* hostname must contain a dot and not be the 1st char */
        hdot = strnstr(h, ".", hlen);
        if (hdot == NULL || hdot == h)
                return (0);
        hdotidx = hdot - h;
        /*
         * host part of hostname must be at least as long as
         * pattern it's supposed to match
         */
        if (hdotidx < mdot1idx)
                return (0);
        /*
         * don't allow wildcards in non-traditional domain names
         * (IDN, A-label, U-label...)
         */
        if (!fetch_ssl_is_trad_domain_label(h, hdotidx, 0) ||
            !fetch_ssl_is_trad_domain_label(m, mdot1idx, 1))
                return (0);
        /* match domain part (part after first dot) */
        if (!fetch_ssl_hname_equal(hdot, hlen - hdotidx, mdot1,
            mlen - mdot1idx))
                return (0);
        /* match part left of wildcard */
        if (!fetch_ssl_hname_equal(h, wcidx, m, wcidx))
                return (0);
        /* match part right of wildcard */
        delta = mdot1idx - wcidx - 1;
        if (!fetch_ssl_hname_equal(hdot - delta, delta,
            mdot1 - delta, delta))
                return (0);
        /* all tests succeeded, it's a match */
        return (1);
}

/*
 * Get numeric host address info - returns NULL if host was not an IP
 * address. The caller is responsible for deallocation using
 * freeaddrinfo(3).
 */
static struct addrinfo *
fetch_ssl_get_numeric_addrinfo(const char *hostname, size_t len)
{
        struct addrinfo hints, *res;
        char *host;

        host = (char *)malloc(len + 1);
        memcpy(host, hostname, len);
        host[len] = '\0';
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = PF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = 0;
        hints.ai_flags = AI_NUMERICHOST;
        /* port is not relevant for this purpose */
        if (getaddrinfo(host, "443", &hints, &res) != 0)
                res = NULL;
        free(host);
        return res;
}

/*
 * Compare ip address in addrinfo with address passes.
 */
static int
fetch_ssl_ipaddr_match_bin(const struct addrinfo *lhost, const char *rhost,
    size_t rhostlen)
{
        const void *left;

        if (lhost->ai_family == AF_INET && rhostlen == 4) {
                left = (void *)&((struct sockaddr_in*)(void *)
                    lhost->ai_addr)->sin_addr.s_addr;
#ifdef INET6
        } else if (lhost->ai_family == AF_INET6 && rhostlen == 16) {
                left = (void *)&((struct sockaddr_in6 *)(void *)
                    lhost->ai_addr)->sin6_addr;
#endif
        } else
                return (0);
        return (!memcmp(left, (const void *)rhost, rhostlen) ? 1 : 0);
}

/*
 * Compare ip address in addrinfo with host passed. If host is not an IP
 * address, comparison will fail.
 */
static int
fetch_ssl_ipaddr_match(const struct addrinfo *laddr, const char *r,
    size_t rlen)
{
        struct addrinfo *raddr;
        int ret;
        char *rip;

        ret = 0;
        if ((raddr = fetch_ssl_get_numeric_addrinfo(r, rlen)) == NULL)
                return 0; /* not a numeric host */

        if (laddr->ai_family == raddr->ai_family) {
                if (laddr->ai_family == AF_INET) {
                        rip = (char *)&((struct sockaddr_in *)(void *)
                            raddr->ai_addr)->sin_addr.s_addr;
                        ret = fetch_ssl_ipaddr_match_bin(laddr, rip, 4);
#ifdef INET6
                } else if (laddr->ai_family == AF_INET6) {
                        rip = (char *)&((struct sockaddr_in6 *)(void *)
                            raddr->ai_addr)->sin6_addr;
                        ret = fetch_ssl_ipaddr_match_bin(laddr, rip, 16);
#endif
                }

        }
        freeaddrinfo(raddr);
        return (ret);
}

/*
 * Verify server certificate by subjectAltName.
 */
static int
fetch_ssl_verify_altname(STACK_OF(GENERAL_NAME) *altnames,
    const char *host, struct addrinfo *ip)
{
        const GENERAL_NAME *name;
        size_t nslen;
        int i;
        const char *ns;

        for (i = 0; i < sk_GENERAL_NAME_num(altnames); ++i) {
                name = sk_GENERAL_NAME_value(altnames, i);
                ns = (const char *)ASN1_STRING_get0_data(name->d.ia5);
                nslen = (size_t)ASN1_STRING_length(name->d.ia5);

                if (name->type == GEN_DNS && ip == NULL &&
                    fetch_ssl_hname_match(host, strlen(host), ns, nslen))
                        return (1);
                else if (name->type == GEN_IPADD && ip != NULL &&
                    fetch_ssl_ipaddr_match_bin(ip, ns, nslen))
                        return (1);
        }
        return (0);
}

/*
 * Verify server certificate by CN.
 */
static int
fetch_ssl_verify_cn(X509_NAME *subject, const char *host,
    struct addrinfo *ip)
{
        ASN1_STRING *namedata;
        X509_NAME_ENTRY *nameentry;
        int cnlen, lastpos, loc, ret;
        unsigned char *cn;

        ret = 0;
        lastpos = -1;
        loc = -1;
        cn = NULL;
        /* get most specific CN (last entry in list) and compare */
        while ((lastpos = X509_NAME_get_index_by_NID(subject,
            NID_commonName, lastpos)) != -1)
                loc = lastpos;

        if (loc > -1) {
                nameentry = X509_NAME_get_entry(subject, loc);
                namedata = X509_NAME_ENTRY_get_data(nameentry);
                cnlen = ASN1_STRING_to_UTF8(&cn, namedata);
                if (ip == NULL &&
                    fetch_ssl_hname_match(host, strlen(host), cn, cnlen))
                        ret = 1;
                else if (ip != NULL && fetch_ssl_ipaddr_match(ip, cn, cnlen))
                        ret = 1;
                OPENSSL_free(cn);
        }
        return (ret);
}

/*
 * Verify that server certificate subjectAltName/CN matches
 * hostname. First check, if there are alternative subject names. If yes,
 * those have to match. Only if those don't exist it falls back to
 * checking the subject's CN.
 */
static int
fetch_ssl_verify_hname(X509 *cert, const char *host)
{
        struct addrinfo *ip;
        STACK_OF(GENERAL_NAME) *altnames;
        X509_NAME *subject;
        int ret;

        ret = 0;
        ip = fetch_ssl_get_numeric_addrinfo(host, strlen(host));
        altnames = X509_get_ext_d2i(cert, NID_subject_alt_name,
            NULL, NULL);

        if (altnames != NULL) {
                ret = fetch_ssl_verify_altname(altnames, host, ip);
        } else {
                subject = X509_get_subject_name(cert);
                if (subject != NULL)
                        ret = fetch_ssl_verify_cn(subject, host, ip);
        }

        if (ip != NULL)
                freeaddrinfo(ip);
        if (altnames != NULL)
                GENERAL_NAMES_free(altnames);
        return (ret);
}

/*
 * Configure transport security layer based on environment.
 */
static void
fetch_ssl_setup_transport_layer(SSL_CTX *ctx, int verbose)
{
        long ssl_ctx_options;

        ssl_ctx_options = SSL_OP_ALL | SSL_OP_NO_SSLv3 | SSL_OP_NO_TICKET;
        if (getenv("SSL_NO_TLS1") != NULL)
                ssl_ctx_options |= SSL_OP_NO_TLSv1;
        if (getenv("SSL_NO_TLS1_1") != NULL)
                ssl_ctx_options |= SSL_OP_NO_TLSv1_1;
        if (getenv("SSL_NO_TLS1_2") != NULL)
                ssl_ctx_options |= SSL_OP_NO_TLSv1_2;
        if (getenv("SSL_NO_TLS1_3") != NULL)
                ssl_ctx_options |= SSL_OP_NO_TLSv1_3;
        fetch_verbose("SSL options: %lx", ssl_ctx_options);
        SSL_CTX_set_options(ctx, ssl_ctx_options);
}


/*
 * Configure peer verification based on environment.
 */
static int
fetch_ssl_setup_peer_verification(SSL_CTX *ctx, int verbose)
{
        X509_LOOKUP *crl_lookup;
        X509_STORE *crl_store;
        const char *ca_cert_file, *ca_cert_path, *crl_file;

        if (getenv("SSL_NO_VERIFY_PEER") == NULL) {
                ca_cert_file = getenv("SSL_CA_CERT_FILE");
                ca_cert_path = getenv("SSL_CA_CERT_PATH");
                if (verbose) {
                        fetch_info("Peer verification enabled");
                        if (ca_cert_file != NULL)
                                fetch_info("Using CA cert file: %s",
                                    ca_cert_file);
                        if (ca_cert_path != NULL)
                                fetch_info("Using CA cert path: %s",
                                    ca_cert_path);
                        if (ca_cert_file == NULL && ca_cert_path == NULL)
                                fetch_info("Using OpenSSL default "
                                    "CA cert file and path");
                }
                SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER,
                    fetch_ssl_cb_verify_crt);
                if (ca_cert_file != NULL || ca_cert_path != NULL)
                        SSL_CTX_load_verify_locations(ctx, ca_cert_file,
                            ca_cert_path);
                else
                        SSL_CTX_set_default_verify_paths(ctx);
                if ((crl_file = getenv("SSL_CRL_FILE")) != NULL) {
                        fetch_verbose("Using CRL file: %s", crl_file);
                        crl_store = SSL_CTX_get_cert_store(ctx);
                        crl_lookup = X509_STORE_add_lookup(crl_store,
                            X509_LOOKUP_file());
                        if (crl_lookup == NULL ||
                            !X509_load_crl_file(crl_lookup, crl_file,
                                X509_FILETYPE_PEM)) {
                                fetch_info("Could not load CRL file %s",
                                    crl_file);
                                return (0);
                        }
                        X509_STORE_set_flags(crl_store,
                            X509_V_FLAG_CRL_CHECK |
                            X509_V_FLAG_CRL_CHECK_ALL);
                }
        }
        return (1);
}

/*
 * Configure client certificate based on environment.
 */
static int
fetch_ssl_setup_client_certificate(SSL_CTX *ctx, int verbose)
{
        const char *client_cert_file, *client_key_file;

        if ((client_cert_file = getenv("SSL_CLIENT_CERT_FILE")) != NULL) {
                client_key_file = getenv("SSL_CLIENT_KEY_FILE") != NULL ?
                    getenv("SSL_CLIENT_KEY_FILE") : client_cert_file;
                fetch_verbose("Using client cert file: %s", client_cert_file);
                fetch_verbose("Using client key file: %s", client_key_file);
                if (SSL_CTX_use_certificate_chain_file(ctx,
                        client_cert_file) != 1) {
                        fetch_info("Could not load client certificate %s",
                            client_cert_file);
                        return (0);
                }
                if (SSL_CTX_use_PrivateKey_file(ctx, client_key_file,
                        SSL_FILETYPE_PEM) != 1) {
                        fetch_info("Could not load client key %s",
                            client_key_file);
                        return (0);
                }
        }
        return (1);
}

/*
 * Callback for SSL certificate verification, this is called on server
 * cert verification. It takes no decision, but informs the user in case
 * verification failed.
 */
int
fetch_ssl_cb_verify_crt(int verified, X509_STORE_CTX *ctx)
{
        X509 *crt;
        X509_NAME *name;
        char *str;

        str = NULL;
        if (!verified) {
                if ((crt = X509_STORE_CTX_get_current_cert(ctx)) != NULL &&
                    (name = X509_get_subject_name(crt)) != NULL)
                        str = X509_NAME_oneline(name, 0, 0);
                fetch_info("Certificate verification failed for %s",
                    str != NULL ? str : "no relevant certificate");
                OPENSSL_free(str);
        }
        return (verified);
}

#endif

/*
 * Enable SSL on a connection.
 */
int
fetch_ssl(conn_t *conn, const struct url *URL, int verbose)
{
#ifdef WITH_SSL
        int ret, ssl_err;
        X509_NAME *name;
        char *str;

        if ((conn->ssl_ctx = SSL_CTX_new(TLS_client_method())) == NULL) {
                fetch_info("SSL context creation failed");
                ERR_print_errors_fp(stderr);
                return (-1);
        }
        SSL_CTX_set_mode(conn->ssl_ctx, SSL_MODE_AUTO_RETRY);

        fetch_ssl_setup_transport_layer(conn->ssl_ctx, verbose);
        if (!fetch_ssl_setup_peer_verification(conn->ssl_ctx, verbose))
                return (-1);
        if (!fetch_ssl_setup_client_certificate(conn->ssl_ctx, verbose))
                return (-1);

        conn->ssl = SSL_new(conn->ssl_ctx);
        if (conn->ssl == NULL) {
                fetch_info("SSL connection creation failed");
                ERR_print_errors_fp(stderr);
                return (-1);
        }
        SSL_set_fd(conn->ssl, conn->sd);

#if !defined(OPENSSL_NO_TLSEXT)
        if (!SSL_set_tlsext_host_name(conn->ssl, __DECONST(char *, URL->host))) {
                fetch_info("Failed to set TLS server name indication for host %s",
                    URL->host);
                return (-1);
        }
#endif
        while ((ret = SSL_connect(conn->ssl)) == -1) {
                ssl_err = SSL_get_error(conn->ssl, ret);
                if (ssl_err != SSL_ERROR_WANT_READ &&
                    ssl_err != SSL_ERROR_WANT_WRITE) {
                        ERR_print_errors_fp(stderr);
                        return (-1);
                }
        }
        conn->ssl_cert = SSL_get_peer_certificate(conn->ssl);

        if (conn->ssl_cert == NULL) {
                fetch_info("No server SSL certificate");
                return (-1);
        }

        if (getenv("SSL_NO_VERIFY_HOSTNAME") == NULL) {
                fetch_verbose("Verify hostname");
                if (!fetch_ssl_verify_hname(conn->ssl_cert, URL->host)) {
                        fetch_info("SSL certificate subject does not match host %s",
                            URL->host);
                        return (-1);
                }
        }

        if (verbose) {
                fetch_info("%s connection established using %s",
                    SSL_get_version(conn->ssl), SSL_get_cipher(conn->ssl));
                name = X509_get_subject_name(conn->ssl_cert);
                str = X509_NAME_oneline(name, 0, 0);
                fetch_info("Certificate subject: %s", str);
                OPENSSL_free(str);
                name = X509_get_issuer_name(conn->ssl_cert);
                str = X509_NAME_oneline(name, 0, 0);
                fetch_info("Certificate issuer: %s", str);
                OPENSSL_free(str);
        }

        return (0);
#else
        (void)conn;
        (void)verbose;
        (void)URL;
        fetch_info("SSL support disabled");
        return (-1);
#endif
}

#define FETCH_READ_WAIT         -2
#define FETCH_READ_ERROR        -1
#define FETCH_READ_DONE          0

#ifdef WITH_SSL
static ssize_t
fetch_ssl_read(SSL *ssl, char *buf, size_t len)
{
        ssize_t rlen;
        int ssl_err;

        rlen = SSL_read(ssl, buf, len);
        if (rlen < 0) {
                ssl_err = SSL_get_error(ssl, rlen);
                if (ssl_err == SSL_ERROR_WANT_READ ||
                    ssl_err == SSL_ERROR_WANT_WRITE) {
                        return (FETCH_READ_WAIT);
                } else {
                        ERR_print_errors_fp(stderr);
                        return (FETCH_READ_ERROR);
                }
        }
        return (rlen);
}
#endif

static ssize_t
fetch_socket_read(int sd, char *buf, size_t len)
{
        ssize_t rlen;

        rlen = read(sd, buf, len);
        if (rlen < 0) {
                if (errno == EAGAIN || (errno == EINTR && fetchRestartCalls)) {
                        return (FETCH_READ_WAIT);
                } else {
                        return (FETCH_READ_ERROR);
                }
        }
        return (rlen);
}

/*
 * Read a character from a connection w/ timeout
 */
ssize_t
fetch_read(conn_t *conn, char *buf, size_t len)
{
        struct timeval now, timeout, delta;
        struct pollfd pfd;
        ssize_t rlen;
        int deltams;

        if (fetchTimeout > 0) {
                gettimeofday(&timeout, NULL);
                timeout.tv_sec += fetchTimeout;
        }

        deltams = INFTIM;
        memset(&pfd, 0, sizeof pfd);
        pfd.fd = conn->sd;
        pfd.events = POLLIN | POLLERR;

        for (;;) {
                /*
                 * The socket is non-blocking.  Instead of the canonical
                 * poll() -> read(), we do the following:
                 *
                 * 1) call read() or SSL_read().
                 * 2) if we received some data, return it.
                 * 3) if an error occurred, return -1.
                 * 4) if read() or SSL_read() signaled EOF, return.
                 * 5) if we did not receive any data but we're not at EOF,
                 *    call poll().
                 *
                 * In the SSL case, this is necessary because if we
                 * receive a close notification, we have to call
                 * SSL_read() one additional time after we've read
                 * everything we received.
                 *
                 * In the non-SSL case, it may improve performance (very
                 * slightly) when reading small amounts of data.
                 */
#ifdef WITH_SSL
                if (conn->ssl != NULL)
                        rlen = fetch_ssl_read(conn->ssl, buf, len);
                else
#endif
                        rlen = fetch_socket_read(conn->sd, buf, len);
                if (rlen >= 0) {
                        break;
                } else if (rlen == FETCH_READ_ERROR) {
                        fetch_syserr();
                        return (-1);
                }
                // assert(rlen == FETCH_READ_WAIT);
                if (fetchTimeout > 0) {
                        gettimeofday(&now, NULL);
                        if (!timercmp(&timeout, &now, >)) {
                                errno = ETIMEDOUT;
                                fetch_syserr();
                                return (-1);
                        }
                        timersub(&timeout, &now, &delta);
                        deltams = delta.tv_sec * 1000 +
                            delta.tv_usec / 1000;
                }
                errno = 0;
                pfd.revents = 0;
                if (poll(&pfd, 1, deltams) < 0) {
                        if (errno == EINTR && fetchRestartCalls)
                                continue;
                        fetch_syserr();
                        return (-1);
                }
        }
        return (rlen);
}


/*
 * Read a line of text from a connection w/ timeout
 */
#define MIN_BUF_SIZE 1024

int
fetch_getln(conn_t *conn)
{
        char *tmp;
        size_t tmpsize;
        ssize_t len;
        char c;

        if (conn->buf == NULL) {
                if ((conn->buf = malloc(MIN_BUF_SIZE)) == NULL) {
                        errno = ENOMEM;
                        return (-1);
                }
                conn->bufsize = MIN_BUF_SIZE;
        }

        conn->buf[0] = '\0';
        conn->buflen = 0;

        do {
                len = fetch_read(conn, &c, 1);
                if (len == -1)
                        return (-1);
                if (len == 0)
                        break;
                conn->buf[conn->buflen++] = c;
                if (conn->buflen == conn->bufsize) {
                        tmp = conn->buf;
                        tmpsize = conn->bufsize * 2 + 1;
                        if ((tmp = realloc(tmp, tmpsize)) == NULL) {
                                errno = ENOMEM;
                                return (-1);
                        }
                        conn->buf = tmp;
                        conn->bufsize = tmpsize;
                }
        } while (c != '\n');

        conn->buf[conn->buflen] = '\0';
        DEBUGF("<<< %s", conn->buf);
        return (0);
}


/*
 * Write to a connection w/ timeout
 */
ssize_t
fetch_write(conn_t *conn, const char *buf, size_t len)
{
        struct iovec iov;

        iov.iov_base = __DECONST(char *, buf);
        iov.iov_len = len;
        return (fetch_writev(conn, &iov, 1));
}

/*
 * Write a vector to a connection w/ timeout
 * Note: can modify the iovec.
 */
ssize_t
fetch_writev(conn_t *conn, struct iovec *iov, int iovcnt)
{
        struct timeval now, timeout, delta;
        struct pollfd pfd;
        ssize_t wlen, total;
        int deltams;

        memset(&pfd, 0, sizeof pfd);
        if (fetchTimeout) {
                pfd.fd = conn->sd;
                pfd.events = POLLOUT | POLLERR;
                gettimeofday(&timeout, NULL);
                timeout.tv_sec += fetchTimeout;
        }

        total = 0;
        while (iovcnt > 0) {
                while (fetchTimeout && pfd.revents == 0) {
                        gettimeofday(&now, NULL);
                        if (!timercmp(&timeout, &now, >)) {
                                errno = ETIMEDOUT;
                                fetch_syserr();
                                return (-1);
                        }
                        timersub(&timeout, &now, &delta);
                        deltams = delta.tv_sec * 1000 +
                            delta.tv_usec / 1000;
                        errno = 0;
                        pfd.revents = 0;
                        if (poll(&pfd, 1, deltams) < 0) {
                                /* POSIX compliance */
                                if (errno == EAGAIN)
                                        continue;
                                if (errno == EINTR && fetchRestartCalls)
                                        continue;
                                return (-1);
                        }
                }
                errno = 0;
#ifdef WITH_SSL
                if (conn->ssl != NULL)
                        wlen = SSL_write(conn->ssl,
                            iov->iov_base, iov->iov_len);
                else
#endif
                        wlen = writev(conn->sd, iov, iovcnt);
                if (wlen == 0) {
                        /* we consider a short write a failure */
                        /* XXX perhaps we shouldn't in the SSL case */
                        errno = EPIPE;
                        fetch_syserr();
                        return (-1);
                }
                if (wlen < 0) {
                        if (errno == EINTR && fetchRestartCalls)
                                continue;
                        return (-1);
                }
                total += wlen;
                while (iovcnt > 0 && wlen >= (ssize_t)iov->iov_len) {
                        wlen -= iov->iov_len;
                        iov++;
                        iovcnt--;
                }
                if (iovcnt > 0) {
                        iov->iov_len -= wlen;
                        iov->iov_base = __DECONST(char *, iov->iov_base) + wlen;
                }
        }
        return (total);
}


/*
 * Write a line of text to a connection w/ timeout
 */
int
fetch_putln(conn_t *conn, const char *str, size_t len)
{
        struct iovec iov[2];
        int ret;

        DEBUGF(">>> %s\n", str);
        iov[0].iov_base = __DECONST(char *, str);
        iov[0].iov_len = len;
        iov[1].iov_base = __DECONST(char *, ENDL);
        iov[1].iov_len = sizeof(ENDL);
        if (len == 0)
                ret = fetch_writev(conn, &iov[1], 1);
        else
                ret = fetch_writev(conn, iov, 2);
        if (ret == -1)
                return (-1);
        return (0);
}


/*
 * Close connection
 */
int
fetch_close(conn_t *conn)
{
        int ret;

        if (--conn->ref > 0)
                return (0);
#ifdef WITH_SSL
        if (conn->ssl) {
                SSL_shutdown(conn->ssl);
                SSL_set_connect_state(conn->ssl);
                SSL_free(conn->ssl);
                conn->ssl = NULL;
        }
        if (conn->ssl_ctx) {
                SSL_CTX_free(conn->ssl_ctx);
                conn->ssl_ctx = NULL;
        }
        if (conn->ssl_cert) {
                X509_free(conn->ssl_cert);
                conn->ssl_cert = NULL;
        }
#endif
        ret = close(conn->sd);
        free(conn->buf);
        free(conn);
        return (ret);
}


/*** Directory-related utility functions *************************************/

int
fetch_add_entry(struct url_ent **p, int *size, int *len,
    const char *name, struct url_stat *us)
{
        struct url_ent *tmp;

        if (*p == NULL) {
                *size = 0;
                *len = 0;
        }

        if (*len >= *size - 1) {
                tmp = reallocarray(*p, *size * 2 + 1, sizeof(**p));
                if (tmp == NULL) {
                        errno = ENOMEM;
                        fetch_syserr();
                        return (-1);
                }
                *size = (*size * 2 + 1);
                *p = tmp;
        }

        tmp = *p + *len;
        snprintf(tmp->name, PATH_MAX, "%s", name);
        memcpy(&tmp->stat, us, sizeof(*us));

        (*len)++;
        (++tmp)->name[0] = 0;

        return (0);
}


/*** Authentication-related utility functions ********************************/

static const char *
fetch_read_word(FILE *f)
{
        static char word[1024];

        if (fscanf(f, " %1023s ", word) != 1)
                return (NULL);
        return (word);
}

static int
fetch_netrc_open(void)
{
        struct passwd *pwd;
        char fn[PATH_MAX];
        const char *p;
        int fd, serrno;

        if ((p = getenv("NETRC")) != NULL) {
                DEBUGF("NETRC=%s\n", p);
                if (snprintf(fn, sizeof(fn), "%s", p) >= (int)sizeof(fn)) {
                        fetch_info("$NETRC specifies a file name "
                            "longer than PATH_MAX");
                        return (-1);
                }
        } else {
                if ((p = getenv("HOME")) == NULL) {
                        if ((pwd = getpwuid(getuid())) == NULL ||
                            (p = pwd->pw_dir) == NULL)
                                return (-1);
                }
                if (snprintf(fn, sizeof(fn), "%s/.netrc", p) >= (int)sizeof(fn))
                        return (-1);
        }

        if ((fd = open(fn, O_RDONLY)) < 0) {
                serrno = errno;
                DEBUGF("%s: %s\n", fn, strerror(serrno));
                errno = serrno;
        }
        return (fd);
}

/*
 * Get authentication data for a URL from .netrc
 */
int
fetch_netrc_auth(struct url *url)
{
        const char *word;
        int serrno;
        FILE *f;

        if (url->netrcfd < 0)
                url->netrcfd = fetch_netrc_open();
        if (url->netrcfd < 0)
                return (-1);
        if ((f = fdopen(url->netrcfd, "r")) == NULL) {
                serrno = errno;
                DEBUGF("fdopen(netrcfd): %s", strerror(errno));
                close(url->netrcfd);
                url->netrcfd = -1;
                errno = serrno;
                return (-1);
        }
        rewind(f);
        DEBUGF("searching netrc for %s\n", url->host);
        while ((word = fetch_read_word(f)) != NULL) {
                if (strcmp(word, "default") == 0) {
                        DEBUGF("using default netrc settings\n");
                        break;
                }
                if (strcmp(word, "machine") == 0 &&
                    (word = fetch_read_word(f)) != NULL &&
                    strcasecmp(word, url->host) == 0) {
                        DEBUGF("using netrc settings for %s\n", word);
                        break;
                }
        }
        if (word == NULL)
                goto ferr;
        while ((word = fetch_read_word(f)) != NULL) {
                if (strcmp(word, "login") == 0) {
                        if ((word = fetch_read_word(f)) == NULL)
                                goto ferr;
                        if (snprintf(url->user, sizeof(url->user),
                                "%s", word) > (int)sizeof(url->user)) {
                                fetch_info("login name in .netrc is too long");
                                url->user[0] = '\0';
                        }
                } else if (strcmp(word, "password") == 0) {
                        if ((word = fetch_read_word(f)) == NULL)
                                goto ferr;
                        if (snprintf(url->pwd, sizeof(url->pwd),
                                "%s", word) > (int)sizeof(url->pwd)) {
                                fetch_info("password in .netrc is too long");
                                url->pwd[0] = '\0';
                        }
                } else if (strcmp(word, "account") == 0) {
                        if ((word = fetch_read_word(f)) == NULL)
                                goto ferr;
                        /* XXX not supported! */
                } else {
                        break;
                }
        }
        fclose(f);
        url->netrcfd = -1;
        return (0);
ferr:
        serrno = errno;
        fclose(f);
        url->netrcfd = -1;
        errno = serrno;
        return (-1);
}

/*
 * The no_proxy environment variable specifies a set of domains for
 * which the proxy should not be consulted; the contents is a comma-,
 * or space-separated list of domain names.  A single asterisk will
 * override all proxy variables and no transactions will be proxied
 * (for compatibility with lynx and curl, see the discussion at
 * <http://curl.haxx.se/mail/archive_pre_oct_99/0009.html>).
 */
int
fetch_no_proxy_match(const char *host)
{
        const char *no_proxy, *p, *q;
        size_t h_len, d_len;

        if ((no_proxy = getenv("NO_PROXY")) == NULL &&
            (no_proxy = getenv("no_proxy")) == NULL)
                return (0);

        /* asterisk matches any hostname */
        if (strcmp(no_proxy, "*") == 0)
                return (1);

        h_len = strlen(host);
        p = no_proxy;
        do {
                /* position p at the beginning of a domain suffix */
                while (*p == ',' || isspace((unsigned char)*p))
                        p++;

                /* position q at the first separator character */
                for (q = p; *q; ++q)
                        if (*q == ',' || isspace((unsigned char)*q))
                                break;

                d_len = q - p;
                if (d_len > 0 && h_len >= d_len &&
                    strncasecmp(host + h_len - d_len,
                        p, d_len) == 0) {
                        /* domain name matches */
                        return (1);
                }

                p = q + 1;
        } while (*q);

        return (0);
}