/*-
 * Copyright (c) 2000-2004 Dag-Erling Coïdan Smørgrav
 * 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 "free2net.h"

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libfetch/http.c,v 1.76.2.2 2007/05/29 12:35:26 des Exp $");

/*
 * The following copyright applies to the base64 code:
 *
 *-
 * Copyright 1997 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. 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 <ctype.h>
#include <err.h>
#include <errno.h>
#include <locale.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <netinet/in.h>
#include <netinet/tcp.h>

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

#include "free2net.h"

/* Maximum number of redirects to follow */
#define MAX_REDIRECT 5

/* Symbolic names for reply codes we care about */
#define HTTP_OK                 200
#define HTTP_PARTIAL            206
#define HTTP_MOVED_PERM         301
#define HTTP_MOVED_TEMP         302
#define HTTP_SEE_OTHER          303
#define HTTP_TEMP_REDIRECT      307
#define HTTP_NEED_AUTH          401
#define HTTP_NEED_PROXY_AUTH    407
#define HTTP_BAD_RANGE          416
#define HTTP_PROTOCOL_ERROR     999

#define HTTP_REDIRECT(xyz) ((xyz) == HTTP_MOVED_PERM \
                            || (xyz) == HTTP_MOVED_TEMP \
                            || (xyz) == HTTP_TEMP_REDIRECT \
                            || (xyz) == HTTP_SEE_OTHER)

#define HTTP_ERROR(xyz) ((xyz) > 400 && (xyz) < 599)


/*****************************************************************************
 * I/O functions for decoding chunked streams
 */

struct httpio
{
        conn_t          *conn;          /* connection */
        int              chunked;       /* chunked mode */
        char            *buf;           /* chunk buffer */
        size_t           bufsize;       /* size of chunk buffer */
        ssize_t          buflen;        /* amount of data currently in buffer */
        int              bufpos;        /* current read offset in buffer */
        int              eof;           /* end-of-file flag */
        int              error;         /* error flag */
        size_t           chunksize;     /* remaining size of current chunk */
#ifndef NDEBUG
        size_t           total;
#endif
};


/*
 * Get next chunk header
 */
static int
_http_new_chunk(struct httpio *io)
{
        char *p;

        if (_fetch_getln(io->conn) == -1)
                return (-1);

        if (io->conn->buflen < 2 || !ishexnumber((unsigned)*io->conn->buf))
                return (-1);

        for (p = io->conn->buf; *p && !isspace((unsigned)*p); ++p) {
                if (*p == ';')
                        break;
                if (!ishexnumber((unsigned)*p))
                        return (-1);
                if (isdigit((unsigned)*p)) {
                        io->chunksize = io->chunksize * 16 +
                            *p - '0';
                } else {
                        io->chunksize = io->chunksize * 16 +
                            10 + tolower((unsigned)*p) - 'a';
                }
        }

#ifndef NDEBUG
        if (fetchDebug) {
                io->total += io->chunksize;
                if (io->chunksize == 0)
                        fprintf(stderr, "%s(): end of last chunk\n", __func__);
                else
                        fprintf(stderr, "%s(): new chunk: %lu (%lu)\n",
                            __func__, (unsigned long)io->chunksize,
                            (unsigned long)io->total);
        }
#endif

        return (io->chunksize);
}

/*
 * Grow the input buffer to at least len bytes
 */
static inline int
_http_growbuf(struct httpio *io, size_t len)
{
        char *tmp;

        if (io->bufsize >= len)
                return (0);

        if ((tmp = realloc(io->buf, len)) == NULL)
                return (-1);
        io->buf = tmp;
        io->bufsize = len;
        return (0);
}

/*
 * Fill the input buffer, do chunk decoding on the fly
 */
static int
_http_fillbuf(struct httpio *io, size_t len)
{
        if (io->error)
                return (-1);
        if (io->eof)
                return (0);

        if (io->chunked == 0) {
                if (_http_growbuf(io, len) == -1)
                        return (-1);
                if ((io->buflen = _fetch_read(io->conn, io->buf, len)) == -1) {
                        io->error = 1;
                        return (-1);
                }
                io->bufpos = 0;
                return (io->buflen);
        }

        if (io->chunksize == 0) {
                switch (_http_new_chunk(io)) {
                case -1:
                        io->error = 1;
                        return (-1);
                case 0:
                        io->eof = 1;
                        return (0);
                }
        }

        if (len > io->chunksize)
                len = io->chunksize;
        if (_http_growbuf(io, len) == -1)
                return (-1);
        if ((io->buflen = _fetch_read(io->conn, io->buf, len)) == -1) {
                io->error = 1;
                return (-1);
        }
        io->chunksize -= io->buflen;

        if (io->chunksize == 0) {
                char endl[2];

                if (_fetch_read(io->conn, endl, 2) != 2 ||
                    endl[0] != '\r' || endl[1] != '\n')
                        return (-1);
        }

        io->bufpos = 0;

        return (io->buflen);
}

/*
 * Read function
 */
static int
_http_readfn(void *v, char *buf, int len)
{
        struct httpio *io = (struct httpio *)v;
        int l, pos;

        if (io->error)
                return (-1);
        if (io->eof)
                return (0);

        for (pos = 0; len > 0; pos += l, len -= l) {
                /* empty buffer */
                if (!io->buf || io->bufpos == io->buflen)
                        if (_http_fillbuf(io, (unsigned) len) < 1)
                                break;
                l = io->buflen - io->bufpos;
                if (len < l)
                        l = len;
                bcopy(io->buf + io->bufpos, buf + pos, (unsigned) l);
                io->bufpos += l;
        }

        if (!pos && io->error)
                return (-1);
        return (pos);
}

/*
 * Write function
 */
static int
_http_writefn(void *v, const char *buf, int len)
{
        struct httpio *io = (struct httpio *)v;

        return (_fetch_write(io->conn, buf, (unsigned) len));
}

/*
 * Close function
 */
static int
_http_closefn(void *v)
{
        struct httpio *io = (struct httpio *)v;
        int r;

        r = _fetch_close(io->conn);
        if (io->buf)
                free(io->buf);
        free(io);
        return (r);
}

/*
 * Wrap a file descriptor up
 */
static FILE *
_http_funopen(conn_t *conn, int chunked)
{
        struct httpio *io;
        FILE *f;

        if ((io = calloc(1, sizeof(*io))) == NULL) {
                _fetch_syserr();
                return (NULL);
        }
        io->conn = conn;
        io->chunked = chunked;
        f = funopen(io, _http_readfn, _http_writefn, NULL, _http_closefn);
        if (f == NULL) {
                _fetch_syserr();
                free(io);
                return (NULL);
        }
        return (f);
}


/*****************************************************************************
 * Helper functions for talking to the server and parsing its replies
 */

/* Header types */
typedef enum {
        hdr_syserror = -2,
        hdr_error = -1,
        hdr_end = 0,
        hdr_unknown = 1,
        hdr_content_length,
        hdr_content_range,
        hdr_last_modified,
        hdr_location,
        hdr_transfer_encoding,
        hdr_www_authenticate
} hdr_t;

/* Names of interesting headers */
static struct {
        hdr_t            num;
        const char      *name;
} hdr_names[] = {
        { hdr_content_length,           "Content-Length" },
        { hdr_content_range,            "Content-Range" },
        { hdr_last_modified,            "Last-Modified" },
        { hdr_location,                 "Location" },
        { hdr_transfer_encoding,        "Transfer-Encoding" },
        { hdr_www_authenticate,         "WWW-Authenticate" },
        { hdr_unknown,                  NULL },
};

/*
 * Send a formatted line; optionally echo to terminal
 */
static int
_http_cmd(conn_t *conn, const char *fmt, ...)
{
        va_list ap;
        size_t len;
        char *msg;
        int r;

        va_start(ap, fmt);
        len = vasprintf(&msg, fmt, ap);
        va_end(ap);

        if (msg == NULL) {
                errno = ENOMEM;
                _fetch_syserr();
                return (-1);
        }

        r = _fetch_putln(conn, msg, len);
        free(msg);

        if (r == -1) {
                _fetch_syserr();
                return (-1);
        }

        return (0);
}

/*
 * Get and parse status line
 */
static int
_http_get_reply(conn_t *conn)
{
        char *p;

        if (_fetch_getln(conn) == -1)
                return (-1);
        /*
         * A valid status line looks like "HTTP/m.n xyz reason" where m
         * and n are the major and minor protocol version numbers and xyz
         * is the reply code.
         * Unfortunately, there are servers out there (NCSA 1.5.1, to name
         * just one) that do not send a version number, so we can't rely
         * on finding one, but if we do, insist on it being 1.0 or 1.1.
         * We don't care about the reason phrase.
         */
        if (strncmp(conn->buf, "HTTP", 4) != 0)
                return (HTTP_PROTOCOL_ERROR);
        p = conn->buf + 4;
        if (*p == '/') {
                if (p[1] != '1' || p[2] != '.' || (p[3] != '0' && p[3] != '1'))
                        return (HTTP_PROTOCOL_ERROR);
                p += 4;
        }
        if (*p != ' ' || !isdigit((unsigned)p[1]) || !isdigit((unsigned)p[2]) || !isdigit((unsigned)p[3]))
                return (HTTP_PROTOCOL_ERROR);

        conn->err = (p[1] - '0') * 100 + (p[2] - '0') * 10 + (p[3] - '0');
        return (conn->err);
}

/*
 * Check a header; if the type matches the given string, return a pointer
 * to the beginning of the value.
 */
static const char *
_http_match(const char *str, const char *hdr)
{
        while (*str && *hdr && tolower((unsigned)*str++) == tolower((unsigned)*hdr++))
                /* nothing */;
        if (*str || *hdr != ':')
                return (NULL);
        while (*hdr && isspace((unsigned)*++hdr))
                /* nothing */;
        return (hdr);
}

/*
 * Get the next header and return the appropriate symbolic code.
 */
static hdr_t
_http_next_header(conn_t *conn, const char **p)
{
        int i;

        if (_fetch_getln(conn) == -1)
                return (hdr_syserror);
        while (conn->buflen && isspace((unsigned)conn->buf[conn->buflen - 1]))
                conn->buflen--;
        conn->buf[conn->buflen] = '\0';
        if (conn->buflen == 0)
                return (hdr_end);
        /*
         * We could check for malformed headers but we don't really care.
         * A valid header starts with a token immediately followed by a
         * colon; a token is any sequence of non-control, non-whitespace
         * characters except "()<>@,;:\\\"{}".
         */
        for (i = 0; hdr_names[i].num != hdr_unknown; i++)
                if ((*p = _http_match(hdr_names[i].name, conn->buf)) != NULL)
                        return (hdr_names[i].num);
        return (hdr_unknown);
}

/*
 * Parse a last-modified header
 */
static int
_http_parse_mtime(const char *p, time_t *mtime)
{
        char locale[64], *r;
        struct tm tm;

        strncpy(locale, setlocale(LC_TIME, NULL), sizeof(locale));
        setlocale(LC_TIME, "C");
        r = strptime(p, "%a, %d %b %Y %H:%M:%S GMT", &tm);
        /* XXX should add support for date-2 and date-3 */
        setlocale(LC_TIME, locale);
        if (r == NULL)
                return (-1);
        DEBUG(fprintf(stderr, "last modified: [%04d-%02d-%02d "
                  "%02d:%02d:%02d]\n",
                  tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
                  tm.tm_hour, tm.tm_min, tm.tm_sec));
        *mtime = timegm(&tm);
        return (0);
}

/*
 * Parse a content-length header
 */
static int
_http_parse_length(const char *p, off_t *length)
{
        off_t len;

        for (len = 0; *p && isdigit((unsigned)*p); ++p)
                len = len * 10 + (*p - '0');
        if (*p)
                return (-1);
        DEBUG(fprintf(stderr, "content length: [%lld]\n",
            (long long)len));
        *length = len;
        return (0);
}

/*
 * Parse a content-range header
 */
static int
_http_parse_range(const char *p, off_t *offset, off_t *length, off_t *size)
{
        off_t first, last, len;

        if (strncasecmp(p, "bytes ", 6) != 0)
                return (-1);
        p += 6;
        if (*p == '*') {
                first = last = -1;
                ++p;
        } else {
                for (first = 0; *p && isdigit((unsigned)*p); ++p)
                        first = first * 10 + *p - '0';
                if (*p != '-')
                        return (-1);
                for (last = 0, ++p; *p && isdigit((unsigned)*p); ++p)
                        last = last * 10 + *p - '0';
        }
        if (first > last || *p != '/')
                return (-1);
        for (len = 0, ++p; *p && isdigit((unsigned)*p); ++p)
                len = len * 10 + *p - '0';
        if (*p || len < last - first + 1)
                return (-1);
        if (first == -1) {
                DEBUG(fprintf(stderr, "content range: [*/%lld]\n",
                    (long long)len));
                *length = 0;
        } else {
                DEBUG(fprintf(stderr, "content range: [%lld-%lld/%lld]\n",
                    (long long)first, (long long)last, (long long)len));
                *length = last - first + 1;
        }
        *offset = first;
        *size = len;
        return (0);
}


/*****************************************************************************
 * Helper functions for authorization
 */

/*
 * Base64 encoding
 */
static char *
_http_base64(const char *src)
{
        static const char base64[] =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";
        char *str, *dst;
        size_t l;
        int r;
        unsigned t;

        l = strlen(src);
        if ((str = malloc(((l + 2) / 3) * 4 + 1)) == NULL)
                return (NULL);
        dst = str;
        r = 0;

        while (l >= 3) {
                t = (src[0] << 16) | (src[1] << 8) | src[2];
                dst[0] = base64[(t >> 18) & 0x3f];
                dst[1] = base64[(t >> 12) & 0x3f];
                dst[2] = base64[(t >> 6) & 0x3f];
                dst[3] = base64[(t >> 0) & 0x3f];
                src += 3; l -= 3;
                dst += 4; r += 4;
        }

        switch (l) {
        case 2:
                t = (src[0] << 16) | (src[1] << 8);
                dst[0] = base64[(t >> 18) & 0x3f];
                dst[1] = base64[(t >> 12) & 0x3f];
                dst[2] = base64[(t >> 6) & 0x3f];
                dst[3] = '=';
                dst += 4;
                r += 4;
                break;
        case 1:
                t = src[0] << 16;
                dst[0] = base64[(t >> 18) & 0x3f];
                dst[1] = base64[(t >> 12) & 0x3f];
                dst[2] = dst[3] = '=';
                dst += 4;
                r += 4;
                break;
        case 0:
                break;
        }

        *dst = 0;
        return (str);
}

/*
 * Encode username and password
 */
static int
_http_basic_auth(conn_t *conn, const char *hdr, const char *usr, const char *pwd)
{
        char *upw, *auth;
        int r;

        DEBUG(fprintf(stderr, "usr: [%s]\n", usr));
        DEBUG(fprintf(stderr, "pwd: [%s]\n", pwd));
        if (asprintf(&upw, "%s:%s", usr, pwd) == -1)
                return (-1);
        auth = _http_base64(upw);
        free(upw);
        if (auth == NULL)
                return (-1);
        r = _http_cmd(conn, "%s: Basic %s", hdr, auth);
        free(auth);
        return (r);
}

/*
 * Send an authorization header
 */
static int
_http_authorize(conn_t *conn, const char *hdr, const char *p)
{
        /* basic authorization */
        if (strncasecmp(p, "basic:", 6) == 0) {
                char *user, *pwd, *str;
                int r;

                /* skip realm */
                for (p += 6; *p && *p != ':'; ++p)
                        /* nothing */ ;
                if (!*p || strchr(++p, ':') == NULL)
                        return (-1);
                if ((str = strdup(p)) == NULL)
                        return (-1); /* XXX */
                user = str;
                pwd = strchr(str, ':');
                *pwd++ = '\0';
                r = _http_basic_auth(conn, hdr, user, pwd);
                free(str);
                return (r);
        }
        return (-1);
}


/*****************************************************************************
 * Helper functions for connecting to a server or proxy
 */

/*
 * Connect to the correct HTTP server or proxy.
 */
static conn_t *
_http_connect(struct url *URL, struct url *purl, const char *flags)
{
        conn_t *conn;
        int verbose;
        int af;

#ifdef INET6
        af = AF_UNSPEC;
#else
        af = AF_INET;
#endif

        verbose = CHECK_FLAG('v');
        if (CHECK_FLAG('4'))
                af = AF_INET;
#ifdef INET6
        else if (CHECK_FLAG('6'))
                af = AF_INET6;
#endif

        if (purl && strcasecmp(URL->scheme, SCHEME_HTTPS) != 0) {
                URL = purl;
        } else if (strcasecmp(URL->scheme, SCHEME_FTP) == 0) {
                /* can't talk http to an ftp server */
                /* XXX should set an error code */
                return (NULL);
        }

        if ((conn = _fetch_connect(URL->host, URL->port, af, verbose)) == NULL)
                /* _fetch_connect() has already set an error code */
                return (NULL);
        if (strcasecmp(URL->scheme, SCHEME_HTTPS) == 0 &&
            _fetch_ssl(conn, verbose) == -1) {
                _fetch_close(conn);
                /* grrr */
                errno = EAUTH;
                _fetch_syserr();
                return (NULL);
        }

#ifdef TCP_NOPUSH
        {
                int     val;

                val = 1;
                setsockopt(conn->sd, IPPROTO_TCP, TCP_NOPUSH, &val, sizeof(val));
        }
#endif

        return (conn);
}

static struct url *
_http_get_proxy(const char *flags)
{
        struct url *purl;
        char *p;

        if (flags != NULL && strchr(flags, 'd') != NULL)
                return (NULL);
        if (((p = getenv("HTTP_PROXY")) || (p = getenv("http_proxy"))) &&
            *p && (purl = fetchParseURL(p))) {
                if (!*purl->scheme)
                        strcpy(purl->scheme, SCHEME_HTTP);
                if (!purl->port)
                        purl->port = _fetch_default_proxy_port(purl->scheme);
                if (strcasecmp(purl->scheme, SCHEME_HTTP) == 0)
                        return (purl);
                fetchFreeURL(purl);
        }
        return (NULL);
}

static void
_http_print_html(FILE *out, FILE *in)
{
        size_t len;
        char *line, *p, *q;
        int comment, tag;

        comment = tag = 0;
        while ((line = fgetln(in, &len)) != NULL) {
                while (len && isspace((unsigned)line[len - 1]))
                        --len;
                for (p = q = line; q < line + len; ++q) {
                        if (comment && *q == '-') {
                                if (q + 2 < line + len &&
                                    strcmp(q, "-->") == 0) {
                                        tag = comment = 0;
                                        q += 2;
                                }
                        } else if (tag && !comment && *q == '>') {
                                p = q + 1;
                                tag = 0;
                        } else if (!tag && *q == '<') {
                                if (q > p)
                                        fwrite(p, (unsigned)(q - p), 1, out);
                                tag = 1;
                                if (q + 3 < line + len &&
                                    strcmp(q, "<!--") == 0) {
                                        comment = 1;
                                        q += 3;
                                }
                        }
                }
                if (!tag && q > p)
                        fwrite(p, (unsigned)(q - p), 1, out);
                fputc('\n', out);
        }
}


/*****************************************************************************
 * Core
 */

/*
 * Send a request and process the reply
 *
 * XXX This function is way too long, the do..while loop should be split
 * XXX off into a separate function.
 */
FILE *
_http_request(struct url *URL, const char *op, struct url_stat *us,
    struct url *purl, const char *flags)
{
        conn_t *conn;
        struct url *url, *new;
        int chunked, direct, need_auth, noredirect, verbose;
        int e, i, n, val;
        off_t offset, clength, length, size;
        time_t mtime;
        const char *p;
        FILE *f;
        hdr_t h;
        char hbuf[MAXHOSTNAMELEN + 7], *host;

        direct = CHECK_FLAG('d');
        noredirect = CHECK_FLAG('A');
        verbose = CHECK_FLAG('v');

        if (direct && purl) {
                fetchFreeURL(purl);
                purl = NULL;
        }

        /* try the provided URL first */
        url = URL;

        /* if the A flag is set, we only get one try */
        n = noredirect ? 1 : MAX_REDIRECT;
        i = 0;

        e = HTTP_PROTOCOL_ERROR;
        need_auth = 0;
        do {
                new = NULL;
                chunked = 0;
                offset = 0;
                clength = -1;
                length = -1;
                size = -1;
                mtime = 0;

                /* check port */
                if (!url->port)
                        url->port = _fetch_default_port(url->scheme);

                /* were we redirected to an FTP URL? */
                if (purl == NULL && strcmp(url->scheme, SCHEME_FTP) == 0) {
                        if (strcmp(op, "GET") == 0)
                                return (_ftp_request(url, "RETR", us, purl, flags));
                        else if (strcmp(op, "HEAD") == 0)
                                return (_ftp_request(url, "STAT", us, purl, flags));
                }

                /* connect to server or proxy */
                if ((conn = _http_connect(url, purl, flags)) == NULL)
                        goto ouch;

                host = url->host;
#ifdef INET6
                if (strchr(url->host, ':')) {
                        snprintf(hbuf, sizeof(hbuf), "[%s]", url->host);
                        host = hbuf;
                }
#endif
                if (url->port != _fetch_default_port(url->scheme)) {
                        if (host != hbuf) {
                                strcpy(hbuf, host);
                                host = hbuf;
                        }
                        snprintf(hbuf + strlen(hbuf),
                            sizeof(hbuf) - strlen(hbuf), ":%d", url->port);
                }

                /* send request */
                if (verbose)
                        _fetch_info("requesting %s://%s%s",
                            url->scheme, host, url->doc);
                if (purl) {
                        _http_cmd(conn, "%s %s://%s%s HTTP/1.1",
                            op, url->scheme, host, url->doc);
                } else {
                        _http_cmd(conn, "%s %s HTTP/1.1",
                            op, url->doc);
                }

                /* virtual host */
                _http_cmd(conn, "Host: %s", host);

                /* proxy authorization */
                if (purl) {
                        if (*purl->user || *purl->pwd)
                                _http_basic_auth(conn, "Proxy-Authorization",
                                    purl->user, purl->pwd);
                        else if ((p = getenv("HTTP_PROXY_AUTH")) != NULL && *p != '\0')
                                _http_authorize(conn, "Proxy-Authorization", p);
                }

                /* server authorization */
                if (need_auth || *url->user || *url->pwd) {
                        if (*url->user || *url->pwd)
                                _http_basic_auth(conn, "Authorization", url->user, url->pwd);
                        else if ((p = getenv("HTTP_AUTH")) != NULL && *p != '\0')
                                _http_authorize(conn, "Authorization", p);
                        else if (fetchAuthMethod && fetchAuthMethod(url) == 0) {
                                _http_basic_auth(conn, "Authorization", url->user, url->pwd);
                        } else {
                                _http_seterr(HTTP_NEED_AUTH);
                                goto ouch;
                        }
                }

                /* other headers */
                if ((p = getenv("HTTP_REFERER")) != NULL && *p != '\0') {
                        if (strcasecmp(p, "auto") == 0)
                                _http_cmd(conn, "Referer: %s://%s%s",
                                    url->scheme, host, url->doc);
                        else
                                _http_cmd(conn, "Referer: %s", p);
                }
                if ((p = getenv("HTTP_USER_AGENT")) != NULL && *p != '\0')
                        _http_cmd(conn, "User-Agent: %s", p);
                else
                        _http_cmd(conn, "User-Agent: %s " _LIBFETCH_VER, getprogname());
                if (url->offset > 0)
                        _http_cmd(conn, "Range: bytes=%lld-", (long long)url->offset);
                _http_cmd(conn, "Connection: close");
                _http_cmd(conn, "");

                /*
                 * Force the queued request to be dispatched.  Normally, one
                 * would do this with shutdown(2) but squid proxies can be
                 * configured to disallow such half-closed connections.  To
                 * be compatible with such configurations, fiddle with socket
                 * options to force the pending data to be written.
                 */
                val = 0;
#ifdef TCP_NOPUSH
                setsockopt(conn->sd, IPPROTO_TCP, TCP_NOPUSH, &val,
                           sizeof(val));
#endif
                val = 1;
                setsockopt(conn->sd, IPPROTO_TCP, TCP_NODELAY, &val,
                           sizeof(val));

                /* get reply */
                switch (_http_get_reply(conn)) {
                case HTTP_OK:
                case HTTP_PARTIAL:
                        /* fine */
                        break;
                case HTTP_MOVED_PERM:
                case HTTP_MOVED_TEMP:
                case HTTP_SEE_OTHER:
                        /*
                         * Not so fine, but we still have to read the
                         * headers to get the new location.
                         */
                        break;
                case HTTP_NEED_AUTH:
                        if (need_auth) {
                                /*
                                 * We already sent out authorization code,
                                 * so there's nothing more we can do.
                                 */
                                _http_seterr(conn->err);
                                goto ouch;
                        }
                        /* try again, but send the password this time */
                        if (verbose)
                                _fetch_info("server requires authorization");
                        break;
                case HTTP_NEED_PROXY_AUTH:
                        /*
                         * If we're talking to a proxy, we already sent
                         * our proxy authorization code, so there's
                         * nothing more we can do.
                         */
                        _http_seterr(conn->err);
                        goto ouch;
                case HTTP_BAD_RANGE:
                        /*
                         * This can happen if we ask for 0 bytes because
                         * we already have the whole file.  Consider this
                         * a success for now, and check sizes later.
                         */
                        break;
                case HTTP_PROTOCOL_ERROR:
                        /* fall through */
                case -1:
                        _fetch_syserr();
                        goto ouch;
                default:
                        _http_seterr(conn->err);
                        if (!verbose)
                                goto ouch;
                        /* fall through so we can get the full error message */
                }

                /* get headers */
                do {
                        switch ((h = _http_next_header(conn, &p))) {
                        case hdr_syserror:
                                _fetch_syserr();
                                goto ouch;
                        case hdr_error:
                                _http_seterr(HTTP_PROTOCOL_ERROR);
                                goto ouch;
                        case hdr_content_length:
                                _http_parse_length(p, &clength);
                                break;
                        case hdr_content_range:
                                _http_parse_range(p, &offset, &length, &size);
                                break;
                        case hdr_last_modified:
                                _http_parse_mtime(p, &mtime);
                                break;
                        case hdr_location:
                                if (!HTTP_REDIRECT(conn->err))
                                        break;
                                if (new)
                                        free(new);
                                if (verbose)
                                        _fetch_info("%d redirect to %s", conn->err, p);
                                if (*p == '/')
                                        /* absolute path */
                                        new = fetchMakeURL(url->scheme, url->host, url->port, p,
                                            url->user, url->pwd);
                                else
                                        new = fetchParseURL(p);
                                if (new == NULL) {
                                        /* XXX should set an error code */
                                        DEBUG(fprintf(stderr, "failed to parse new URL\n"));
                                        goto ouch;
                                }
                                if (!*new->user && !*new->pwd) {
                                        strcpy(new->user, url->user);
                                        strcpy(new->pwd, url->pwd);
                                }
                                new->offset = url->offset;
                                new->length = url->length;
                                break;
                        case hdr_transfer_encoding:
                                /* XXX weak test*/
                                chunked = (strcasecmp(p, "chunked") == 0);
                                break;
                        case hdr_www_authenticate:
                                if (conn->err != HTTP_NEED_AUTH)
                                        break;
                                /* if we were smarter, we'd check the method and realm */
                                break;
                        case hdr_end:
                                /* fall through */
                        case hdr_unknown:
                                /* ignore */
                                break;
                        }
                } while (h > hdr_end);

                /* we need to provide authentication */
                if (conn->err == HTTP_NEED_AUTH) {
                        e = conn->err;
                        need_auth = 1;
                        _fetch_close(conn);
                        conn = NULL;
                        continue;
                }

                /* requested range not satisfiable */
                if (conn->err == HTTP_BAD_RANGE) {
                        if (url->offset == size && url->length == 0) {
                                /* asked for 0 bytes; fake it */
                                offset = url->offset;
                                conn->err = HTTP_OK;
                                break;
                        } else {
                                _http_seterr(conn->err);
                                goto ouch;
                        }
                }

                /* we have a hit or an error */
                if (conn->err == HTTP_OK || conn->err == HTTP_PARTIAL || HTTP_ERROR(conn->err))
                        break;

                /* all other cases: we got a redirect */
                e = conn->err;
                need_auth = 0;
                _fetch_close(conn);
                conn = NULL;
                if (!new) {
                        DEBUG(fprintf(stderr, "redirect with no new location\n"));
                        break;
                }
                if (url != URL)
                        fetchFreeURL(url);
                url = new;
        } while (++i < n);

        /* we failed, or ran out of retries */
        if (conn == NULL) {
                _http_seterr(e);
                goto ouch;
        }

        DEBUG(fprintf(stderr, "offset %lld, length %lld,"
                  " size %lld, clength %lld\n",
                  (long long)offset, (long long)length,
                  (long long)size, (long long)clength));

        /* check for inconsistencies */
        if (clength != -1 && length != -1 && clength != length) {
                _http_seterr(HTTP_PROTOCOL_ERROR);
                goto ouch;
        }
        if (clength == -1)
                clength = length;
        if (clength != -1)
                length = offset + clength;
        if (length != -1 && size != -1 && length != size) {
                _http_seterr(HTTP_PROTOCOL_ERROR);
                goto ouch;
        }
        if (size == -1)
                size = length;

        /* fill in stats */
        if (us) {
                us->size = size;
                us->atime = us->mtime = mtime;
        }

        /* too far? */
        if (URL->offset > 0 && offset > URL->offset) {
                _http_seterr(HTTP_PROTOCOL_ERROR);
                goto ouch;
        }

        /* report back real offset and size */
        URL->offset = offset;
        URL->length = (unsigned) clength;

        /* wrap it up in a FILE */
        if ((f = _http_funopen(conn, chunked)) == NULL) {
                _fetch_syserr();
                goto ouch;
        }

        if (url != URL)
                fetchFreeURL(url);
        if (purl)
                fetchFreeURL(purl);

        if (HTTP_ERROR(conn->err)) {
                _http_print_html(stderr, f);
                fclose(f);
                f = NULL;
        }

        return (f);

ouch:
        if (url != URL)
                fetchFreeURL(url);
        if (purl)
                fetchFreeURL(purl);
        if (conn != NULL)
                _fetch_close(conn);
        return (NULL);
}


/*****************************************************************************
 * Entry points
 */

/*
 * Retrieve and stat a file by HTTP
 */
FILE *
fetchXGetHTTP(struct url *URL, struct url_stat *us, const char *flags)
{
        return (_http_request(URL, "GET", us, _http_get_proxy(flags), flags));
}

/*
 * Retrieve a file by HTTP
 */
FILE *
fetchGetHTTP(struct url *URL, const char *flags)
{
        return (fetchXGetHTTP(URL, NULL, flags));
}

/*
 * Store a file by HTTP
 */
/* ARGSUSED0 */
FILE *
fetchPutHTTP(struct url *URL __unused, const char *flags __unused)
{
        warnx("fetchPutHTTP(): not implemented");
        return (NULL);
}

/*
 * Get an HTTP document's metadata
 */
int
fetchStatHTTP(struct url *URL, struct url_stat *us, const char *flags)
{
        FILE *f;

        f = _http_request(URL, "HEAD", us, _http_get_proxy(flags), flags);
        if (f == NULL)
                return (-1);
        fclose(f);
        return (0);
}

/*
 * List a directory
 */
/* ARGSUSED0 */
struct url_ent *
fetchListHTTP(struct url *url __unused, const char *flags __unused)
{
        warnx("fetchListHTTP(): not implemented");
        return (NULL);
}