/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2000-2014 Dag-Erling 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 <sys/cdefs.h>
/*
 * 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 <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <locale.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#ifdef WITH_SSL
#include <openssl/md5.h>
#define MD5Init(c) MD5_Init(c)
#define MD5Update(c, data, len) MD5_Update(c, data, len)
#define MD5Final(md, c) MD5_Final(md, c)
#else
#include <md5.h>
#endif

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

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

/* Maximum number of redirects to follow */
#define MAX_REDIRECT 20

/* 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_NOT_MODIFIED       304
#define HTTP_USE_PROXY          305
#define HTTP_TEMP_REDIRECT      307
#define HTTP_PERM_REDIRECT      308
#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_PERM_REDIRECT \
                            || (xyz) == HTTP_USE_PROXY \
                            || (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 */
        size_t           buflen;        /* amount of data currently in buffer */
        size_t           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 || !isxdigit((unsigned char)*io->conn->buf))
                return (-1);

        for (p = io->conn->buf; *p && !isspace((unsigned char)*p); ++p) {
                if (*p == ';')
                        break;
                if (!isxdigit((unsigned char)*p))
                        return (-1);
                if (isdigit((unsigned char)*p)) {
                        io->chunksize = io->chunksize * 16 +
                            *p - '0';
                } else {
                        io->chunksize = io->chunksize * 16 +
                            10 + tolower((unsigned char)*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 ssize_t
http_fillbuf(struct httpio *io, size_t len)
{
        ssize_t nbytes;
        char ch;

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

        /* not chunked: just fetch the requested amount */
        if (io->chunked == 0) {
                if (http_growbuf(io, len) == -1)
                        return (-1);
                if ((nbytes = fetch_read(io->conn, io->buf, len)) == -1) {
                        io->error = errno;
                        return (-1);
                }
                io->buflen = nbytes;
                io->bufpos = 0;
                return (io->buflen);
        }

        /* chunked, but we ran out: get the next chunk header */
        if (io->chunksize == 0) {
                switch (http_new_chunk(io)) {
                case -1:
                        io->error = EPROTO;
                        return (-1);
                case 0:
                        io->eof = 1;
                        return (0);
                }
        }

        /* fetch the requested amount, but no more than the current chunk */
        if (len > io->chunksize)
                len = io->chunksize;
        if (http_growbuf(io, len) == -1)
                return (-1);
        if ((nbytes = fetch_read(io->conn, io->buf, len)) == -1) {
                io->error = errno;
                return (-1);
        }
        io->bufpos = 0;
        io->buflen = nbytes;
        io->chunksize -= nbytes;

        if (io->chunksize == 0) {
                if (fetch_read(io->conn, &ch, 1) != 1 || ch != '\r' ||
                    fetch_read(io->conn, &ch, 1) != 1 || ch != '\n')
                        return (-1);
        }

        return (io->buflen);
}

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

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

        /* empty buffer */
        if (!io->buf || io->bufpos == io->buflen) {
                if ((rlen = http_fillbuf(io, len)) < 0) {
                        if ((errno = io->error) == EINTR)
                                io->error = 0;
                        return (-1);
                } else if (rlen == 0) {
                        return (0);
                }
        }

        rlen = io->buflen - io->bufpos;
        if (len < rlen)
                rlen = len;
        memcpy(buf, io->buf + io->bufpos, rlen);
        io->bufpos += rlen;
        return (rlen);
}

/*
 * 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, 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_proxy_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_proxy_authenticate,       "Proxy-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 char)p[1]) ||
            !isdigit((unsigned char)p[2]) ||
            !isdigit((unsigned char)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 char)*str++) == tolower((unsigned char)*hdr++))
                /* nothing */;
        if (*str || *hdr != ':')
                return (NULL);
        while (*hdr && isspace((unsigned char)*++hdr))
                /* nothing */;
        return (hdr);
}


/*
 * Get the next header and return the appropriate symbolic code.  We
 * need to read one line ahead for checking for a continuation line
 * belonging to the current header (continuation lines start with
 * white space).
 *
 * We get called with a fresh line already in the conn buffer, either
 * from the previous http_next_header() invocation, or, the first
 * time, from a fetch_getln() performed by our caller.
 *
 * This stops when we encounter an empty line (we dont read beyond the header
 * area).
 *
 * Note that the "headerbuf" is just a place to return the result. Its
 * contents are not used for the next call. This means that no cleanup
 * is needed when ie doing another connection, just call the cleanup when
 * fully done to deallocate memory.
 */

/* Limit the max number of continuation lines to some reasonable value */
#define HTTP_MAX_CONT_LINES 10

/* Place into which to build a header from one or several lines */
typedef struct {
        char    *buf;           /* buffer */
        size_t   bufsize;       /* buffer size */
        size_t   buflen;        /* length of buffer contents */
} http_headerbuf_t;

static void
init_http_headerbuf(http_headerbuf_t *buf)
{
        buf->buf = NULL;
        buf->bufsize = 0;
        buf->buflen = 0;
}

static void
clean_http_headerbuf(http_headerbuf_t *buf)
{
        if (buf->buf)
                free(buf->buf);
        init_http_headerbuf(buf);
}

/* Remove whitespace at the end of the buffer */
static void
http_conn_trimright(conn_t *conn)
{
        while (conn->buflen &&
               isspace((unsigned char)conn->buf[conn->buflen - 1]))
                conn->buflen--;
        conn->buf[conn->buflen] = '\0';
}

static hdr_t
http_next_header(conn_t *conn, http_headerbuf_t *hbuf, const char **p)
{
        unsigned int i, len;

        /*
         * Have to do the stripping here because of the first line. So
         * it's done twice for the subsequent lines. No big deal
         */
        http_conn_trimright(conn);
        if (conn->buflen == 0)
                return (hdr_end);

        /* Copy the line to the headerbuf */
        if (hbuf->bufsize < conn->buflen + 1) {
                if ((hbuf->buf = realloc(hbuf->buf, conn->buflen + 1)) == NULL)
                        return (hdr_syserror);
                hbuf->bufsize = conn->buflen + 1;
        }
        strcpy(hbuf->buf, conn->buf);
        hbuf->buflen = conn->buflen;

        /*
         * Fetch possible continuation lines. Stop at 1st non-continuation
         * and leave it in the conn buffer
         */
        for (i = 0; i < HTTP_MAX_CONT_LINES; i++) {
                if (fetch_getln(conn) == -1)
                        return (hdr_syserror);

                /*
                 * Note: we carry on the idea from the previous version
                 * that a pure whitespace line is equivalent to an empty
                 * one (so it's not continuation and will be handled when
                 * we are called next)
                 */
                http_conn_trimright(conn);
                if (conn->buf[0] != ' ' && conn->buf[0] != "\t"[0])
                        break;

                /* Got a continuation line. Concatenate to previous */
                len = hbuf->buflen + conn->buflen;
                if (hbuf->bufsize < len + 1) {
                        len *= 2;
                        if ((hbuf->buf = realloc(hbuf->buf, len + 1)) == NULL)
                                return (hdr_syserror);
                        hbuf->bufsize = len + 1;
                }
                strcpy(hbuf->buf + hbuf->buflen, conn->buf);
                hbuf->buflen += conn->buflen;
        }

        /*
         * 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, hbuf->buf)) != NULL)
                        return (hdr_names[i].num);

        return (hdr_unknown);
}

/**************************
 * [Proxy-]Authenticate header parsing
 */

/*
 * Read doublequote-delimited string into output buffer obuf (allocated
 * by caller, whose responsibility it is to ensure that it's big enough)
 * cp points to the first char after the initial '"'
 * Handles \ quoting
 * Returns pointer to the first char after the terminating double quote, or
 * NULL for error.
 */
static const char *
http_parse_headerstring(const char *cp, char *obuf)
{
        for (;;) {
                switch (*cp) {
                case 0: /* Unterminated string */
                        *obuf = 0;
                        return (NULL);
                case '"': /* Ending quote */
                        *obuf = 0;
                        return (++cp);
                case '\\':
                        if (*++cp == 0) {
                                *obuf = 0;
                                return (NULL);
                        }
                        /* FALLTHROUGH */
                default:
                        *obuf++ = *cp++;
                }
        }
}

/* Http auth challenge schemes */
typedef enum {HTTPAS_UNKNOWN, HTTPAS_BASIC,HTTPAS_DIGEST} http_auth_schemes_t;

/* Data holder for a Basic or Digest challenge. */
typedef struct {
        http_auth_schemes_t scheme;
        char    *realm;
        char    *qop;
        char    *nonce;
        char    *opaque;
        char    *algo;
        int      stale;
        int      nc; /* Nonce count */
} http_auth_challenge_t;

static void
init_http_auth_challenge(http_auth_challenge_t *b)
{
        b->scheme = HTTPAS_UNKNOWN;
        b->realm = b->qop = b->nonce = b->opaque = b->algo = NULL;
        b->stale = b->nc = 0;
}

static void
clean_http_auth_challenge(http_auth_challenge_t *b)
{
        if (b->realm)
                free(b->realm);
        if (b->qop)
                free(b->qop);
        if (b->nonce)
                free(b->nonce);
        if (b->opaque)
                free(b->opaque);
        if (b->algo)
                free(b->algo);
        init_http_auth_challenge(b);
}

/* Data holder for an array of challenges offered in an http response. */
#define MAX_CHALLENGES 10
typedef struct {
        http_auth_challenge_t *challenges[MAX_CHALLENGES];
        int     count; /* Number of parsed challenges in the array */
        int     valid; /* We did parse an authenticate header */
} http_auth_challenges_t;

static void
init_http_auth_challenges(http_auth_challenges_t *cs)
{
        int i;
        for (i = 0; i < MAX_CHALLENGES; i++)
                cs->challenges[i] = NULL;
        cs->count = cs->valid = 0;
}

static void
clean_http_auth_challenges(http_auth_challenges_t *cs)
{
        int i;
        /* We rely on non-zero pointers being allocated, not on the count */
        for (i = 0; i < MAX_CHALLENGES; i++) {
                if (cs->challenges[i] != NULL) {
                        clean_http_auth_challenge(cs->challenges[i]);
                        free(cs->challenges[i]);
                }
        }
        init_http_auth_challenges(cs);
}

/*
 * Enumeration for lexical elements. Separators will be returned as their own
 * ascii value
 */
typedef enum {HTTPHL_WORD=256, HTTPHL_STRING=257, HTTPHL_END=258,
              HTTPHL_ERROR = 259} http_header_lex_t;

/*
 * Determine what kind of token comes next and return possible value
 * in buf, which is supposed to have been allocated big enough by
 * caller. Advance input pointer and return element type.
 */
static int
http_header_lex(const char **cpp, char *buf)
{
        size_t l;
        /* Eat initial whitespace */
        *cpp += strspn(*cpp, " \t");
        if (**cpp == 0)
                return (HTTPHL_END);

        /* Separator ? */
        if (**cpp == ',' || **cpp == '=')
                return (*((*cpp)++));

        /* String ? */
        if (**cpp == '"') {
                *cpp = http_parse_headerstring(++*cpp, buf);
                if (*cpp == NULL)
                        return (HTTPHL_ERROR);
                return (HTTPHL_STRING);
        }

        /* Read other token, until separator or whitespace */
        l = strcspn(*cpp, " \t,=");
        memcpy(buf, *cpp, l);
        buf[l] = 0;
        *cpp += l;
        return (HTTPHL_WORD);
}

/*
 * Read challenges from http xxx-authenticate header and accumulate them
 * in the challenges list structure.
 *
 * Headers with multiple challenges are specified by rfc2617, but
 * servers (ie: squid) often send them in separate headers instead,
 * which in turn is forbidden by the http spec (multiple headers with
 * the same name are only allowed for pure comma-separated lists, see
 * rfc2616 sec 4.2).
 *
 * We support both approaches anyway
 */
static int
http_parse_authenticate(const char *cp, http_auth_challenges_t *cs)
{
        int ret = -1;
        http_header_lex_t lex;
        char *key = malloc(strlen(cp) + 1);
        char *value = malloc(strlen(cp) + 1);
        char *buf = malloc(strlen(cp) + 1);

        if (key == NULL || value == NULL || buf == NULL) {
                fetch_syserr();
                goto out;
        }

        /* In any case we've seen the header and we set the valid bit */
        cs->valid = 1;

        /* Need word first */
        lex = http_header_lex(&cp, key);
        if (lex != HTTPHL_WORD)
                goto out;

        /* Loop on challenges */
        for (; cs->count < MAX_CHALLENGES; cs->count++) {
                cs->challenges[cs->count] =
                        malloc(sizeof(http_auth_challenge_t));
                if (cs->challenges[cs->count] == NULL) {
                        fetch_syserr();
                        goto out;
                }
                init_http_auth_challenge(cs->challenges[cs->count]);
                if (strcasecmp(key, "basic") == 0) {
                        cs->challenges[cs->count]->scheme = HTTPAS_BASIC;
                } else if (strcasecmp(key, "digest") == 0) {
                        cs->challenges[cs->count]->scheme = HTTPAS_DIGEST;
                } else {
                        cs->challenges[cs->count]->scheme = HTTPAS_UNKNOWN;
                        /*
                         * Continue parsing as basic or digest may
                         * follow, and the syntax is the same for
                         * all. We'll just ignore this one when
                         * looking at the list
                         */
                }

                /* Loop on attributes */
                for (;;) {
                        /* Key */
                        lex = http_header_lex(&cp, key);
                        if (lex != HTTPHL_WORD)
                                goto out;

                        /* Equal sign */
                        lex = http_header_lex(&cp, buf);
                        if (lex != '=')
                                goto out;

                        /* Value */
                        lex = http_header_lex(&cp, value);
                        if (lex != HTTPHL_WORD && lex != HTTPHL_STRING)
                                goto out;

                        if (strcasecmp(key, "realm") == 0) {
                                cs->challenges[cs->count]->realm =
                                    strdup(value);
                        } else if (strcasecmp(key, "qop") == 0) {
                                cs->challenges[cs->count]->qop =
                                    strdup(value);
                        } else if (strcasecmp(key, "nonce") == 0) {
                                cs->challenges[cs->count]->nonce =
                                    strdup(value);
                        } else if (strcasecmp(key, "opaque") == 0) {
                                cs->challenges[cs->count]->opaque =
                                    strdup(value);
                        } else if (strcasecmp(key, "algorithm") == 0) {
                                cs->challenges[cs->count]->algo =
                                    strdup(value);
                        } else if (strcasecmp(key, "stale") == 0) {
                                cs->challenges[cs->count]->stale =
                                    strcasecmp(value, "no");
                        } else {
                                /* ignore unknown attributes */
                        }

                        /* Comma or Next challenge or End */
                        lex = http_header_lex(&cp, key);
                        /*
                         * If we get a word here, this is the beginning of the
                         * next challenge. Break the attributes loop
                         */
                        if (lex == HTTPHL_WORD)
                                break;

                        if (lex == HTTPHL_END) {
                                /* End while looking for ',' is normal exit */
                                cs->count++;
                                ret = 0;
                                goto out;
                        }
                        /* Anything else is an error */
                        if (lex != ',')
                                goto out;

                } /* End attributes loop */
        } /* End challenge loop */

        /*
         * Challenges max count exceeded. This really can't happen
         * with normal data, something's fishy -> error
         */

out:
        if (key)
                free(key);
        if (value)
                free(value);
        if (buf)
                free(buf);
        return (ret);
}


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

        strlcpy(locale, setlocale(LC_TIME, NULL), sizeof(locale));
        setlocale(LC_TIME, "C");
        r = strptime(p, "%a, %d %b %Y %H:%M:%S GMT", &tm);
        /*
         * Some proxies use UTC in response, but it should still be
         * parsed. RFC2616 states GMT and UTC are exactly equal for HTTP.
         */
        if (r == NULL)
                r = strptime(p, "%a, %d %b %Y %H:%M:%S UTC", &tm);
        /* XXX should add support for date-2 and date-3 */
        setlocale(LC_TIME, locale);
        if (r == NULL)
                return (-1);
        DEBUGF("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 char)*p); ++p)
                len = len * 10 + (*p - '0');
        if (*p)
                return (-1);
        DEBUGF("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 char)*p); ++p)
                        first = first * 10 + *p - '0';
                if (*p != '-')
                        return (-1);
                for (last = 0, ++p; *p && isdigit((unsigned char)*p); ++p)
                        last = last * 10 + *p - '0';
        }
        if (first > last || *p != '/')
                return (-1);
        for (len = 0, ++p; *p && isdigit((unsigned char)*p); ++p)
                len = len * 10 + *p - '0';
        if (*p || len < last - first + 1)
                return (-1);
        if (first == -1) {
                DEBUGF("content range: [*/%lld]\n", (long long)len);
                *length = 0;
        } else {
                DEBUGF("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 t;

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

        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;
        }

        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;
                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;
                break;
        case 0:
                break;
        }

        *dst = 0;
        return (str);
}


/*
 * Extract authorization parameters from environment value.
 * The value is like scheme:realm:user:pass
 */
typedef struct {
        char    *scheme;
        char    *realm;
        char    *user;
        char    *password;
} http_auth_params_t;

static void
init_http_auth_params(http_auth_params_t *s)
{
        s->scheme = s->realm = s->user = s->password = NULL;
}

static void
clean_http_auth_params(http_auth_params_t *s)
{
        if (s->scheme)
                free(s->scheme);
        if (s->realm)
                free(s->realm);
        if (s->user)
                free(s->user);
        if (s->password)
                free(s->password);
        init_http_auth_params(s);
}

static int
http_authfromenv(const char *p, http_auth_params_t *parms)
{
        int ret = -1;
        char *v, *ve;
        char *str = strdup(p);

        if (str == NULL) {
                fetch_syserr();
                return (-1);
        }
        v = str;

        if ((ve = strchr(v, ':')) == NULL)
                goto out;

        *ve = 0;
        if ((parms->scheme = strdup(v)) == NULL) {
                fetch_syserr();
                goto out;
        }
        v = ve + 1;

        if ((ve = strchr(v, ':')) == NULL)
                goto out;

        *ve = 0;
        if ((parms->realm = strdup(v)) == NULL) {
                fetch_syserr();
                goto out;
        }
        v = ve + 1;

        if ((ve = strchr(v, ':')) == NULL)
                goto out;

        *ve = 0;
        if ((parms->user = strdup(v)) == NULL) {
                fetch_syserr();
                goto out;
        }
        v = ve + 1;


        if ((parms->password = strdup(v)) == NULL) {
                fetch_syserr();
                goto out;
        }
        ret = 0;
out:
        if (ret == -1)
                clean_http_auth_params(parms);
        if (str)
                free(str);
        return (ret);
}


/*
 * Digest response: the code to compute the digest is taken from the
 * sample implementation in RFC2616
 */
#define IN const
#define OUT

#define HASHLEN 16
typedef char HASH[HASHLEN];
#define HASHHEXLEN 32
typedef char HASHHEX[HASHHEXLEN+1];

static const char *hexchars = "0123456789abcdef";
static void
CvtHex(IN HASH Bin, OUT HASHHEX Hex)
{
        unsigned short i;
        unsigned char j;

        for (i = 0; i < HASHLEN; i++) {
                j = (Bin[i] >> 4) & 0xf;
                Hex[i*2] = hexchars[j];
                j = Bin[i] & 0xf;
                Hex[i*2+1] = hexchars[j];
        }
        Hex[HASHHEXLEN] = '\0';
};

/* calculate H(A1) as per spec */
static void
DigestCalcHA1(
        IN char * pszAlg,
        IN char * pszUserName,
        IN char * pszRealm,
        IN char * pszPassword,
        IN char * pszNonce,
        IN char * pszCNonce,
        OUT HASHHEX SessionKey
        )
{
        MD5_CTX Md5Ctx;
        HASH HA1;

        MD5Init(&Md5Ctx);
        MD5Update(&Md5Ctx, pszUserName, strlen(pszUserName));
        MD5Update(&Md5Ctx, ":", 1);
        MD5Update(&Md5Ctx, pszRealm, strlen(pszRealm));
        MD5Update(&Md5Ctx, ":", 1);
        MD5Update(&Md5Ctx, pszPassword, strlen(pszPassword));
        MD5Final(HA1, &Md5Ctx);
        if (strcasecmp(pszAlg, "md5-sess") == 0) {

                MD5Init(&Md5Ctx);
                MD5Update(&Md5Ctx, HA1, HASHLEN);
                MD5Update(&Md5Ctx, ":", 1);
                MD5Update(&Md5Ctx, pszNonce, strlen(pszNonce));
                MD5Update(&Md5Ctx, ":", 1);
                MD5Update(&Md5Ctx, pszCNonce, strlen(pszCNonce));
                MD5Final(HA1, &Md5Ctx);
        }
        CvtHex(HA1, SessionKey);
}

/* calculate request-digest/response-digest as per HTTP Digest spec */
static void
DigestCalcResponse(
        IN HASHHEX HA1,           /* H(A1) */
        IN char * pszNonce,       /* nonce from server */
        IN char * pszNonceCount,  /* 8 hex digits */
        IN char * pszCNonce,      /* client nonce */
        IN char * pszQop,         /* qop-value: "", "auth", "auth-int" */
        IN char * pszMethod,      /* method from the request */
        IN char * pszDigestUri,   /* requested URL */
        IN HASHHEX HEntity,       /* H(entity body) if qop="auth-int" */
        OUT HASHHEX Response      /* request-digest or response-digest */
        )
{
#if 0
        DEBUGF("Calc: HA1[%s] Nonce[%s] qop[%s] method[%s] URI[%s]\n",
            HA1, pszNonce, pszQop, pszMethod, pszDigestUri);
#endif
        MD5_CTX Md5Ctx;
        HASH HA2;
        HASH RespHash;
        HASHHEX HA2Hex;

        // calculate H(A2)
        MD5Init(&Md5Ctx);
        MD5Update(&Md5Ctx, pszMethod, strlen(pszMethod));
        MD5Update(&Md5Ctx, ":", 1);
        MD5Update(&Md5Ctx, pszDigestUri, strlen(pszDigestUri));
        if (strcasecmp(pszQop, "auth-int") == 0) {
                MD5Update(&Md5Ctx, ":", 1);
                MD5Update(&Md5Ctx, HEntity, HASHHEXLEN);
        }
        MD5Final(HA2, &Md5Ctx);
        CvtHex(HA2, HA2Hex);

        // calculate response
        MD5Init(&Md5Ctx);
        MD5Update(&Md5Ctx, HA1, HASHHEXLEN);
        MD5Update(&Md5Ctx, ":", 1);
        MD5Update(&Md5Ctx, pszNonce, strlen(pszNonce));
        MD5Update(&Md5Ctx, ":", 1);
        if (*pszQop) {
                MD5Update(&Md5Ctx, pszNonceCount, strlen(pszNonceCount));
                MD5Update(&Md5Ctx, ":", 1);
                MD5Update(&Md5Ctx, pszCNonce, strlen(pszCNonce));
                MD5Update(&Md5Ctx, ":", 1);
                MD5Update(&Md5Ctx, pszQop, strlen(pszQop));
                MD5Update(&Md5Ctx, ":", 1);
        }
        MD5Update(&Md5Ctx, HA2Hex, HASHHEXLEN);
        MD5Final(RespHash, &Md5Ctx);
        CvtHex(RespHash, Response);
}

/*
 * Generate/Send a Digest authorization header
 * This looks like: [Proxy-]Authorization: credentials
 *
 *  credentials      = "Digest" digest-response
 *  digest-response  = 1#( username | realm | nonce | digest-uri
 *                      | response | [ algorithm ] | [cnonce] |
 *                      [opaque] | [message-qop] |
 *                          [nonce-count]  | [auth-param] )
 *  username         = "username" "=" username-value
 *  username-value   = quoted-string
 *  digest-uri       = "uri" "=" digest-uri-value
 *  digest-uri-value = request-uri   ; As specified by HTTP/1.1
 *  message-qop      = "qop" "=" qop-value
 *  cnonce           = "cnonce" "=" cnonce-value
 *  cnonce-value     = nonce-value
 *  nonce-count      = "nc" "=" nc-value
 *  nc-value         = 8LHEX
 *  response         = "response" "=" request-digest
 *  request-digest = <"> 32LHEX <">
 */
static int
http_digest_auth(conn_t *conn, const char *hdr, http_auth_challenge_t *c,
                 http_auth_params_t *parms, struct url *url)
{
        int r;
        char noncecount[10];
        char cnonce[40];
        char *options = NULL;

        if (!c->realm || !c->nonce) {
                DEBUGF("realm/nonce not set in challenge\n");
                return(-1);
        }
        if (!c->algo)
                c->algo = strdup("");

        if (asprintf(&options, "%s%s%s%s",
            *c->algo? ",algorithm=" : "", c->algo,
            c->opaque? ",opaque=" : "", c->opaque?c->opaque:"") < 0)
                return (-1);

        if (!c->qop) {
                c->qop = strdup("");
                *noncecount = 0;
                *cnonce = 0;
        } else {
                c->nc++;
                sprintf(noncecount, "%08x", c->nc);
                /* We don't try very hard with the cnonce ... */
                sprintf(cnonce, "%x%lx", getpid(), (unsigned long)time(0));
        }

        HASHHEX HA1;
        DigestCalcHA1(c->algo, parms->user, c->realm,
                      parms->password, c->nonce, cnonce, HA1);
        DEBUGF("HA1: [%s]\n", HA1);
        HASHHEX digest, null;
        memset(null, 0, sizeof(null));
        DigestCalcResponse(HA1, c->nonce, noncecount, cnonce, c->qop,
                           "GET", url->doc, null, digest);

        if (c->qop[0]) {
                r = http_cmd(conn, "%s: Digest username=\"%s\",realm=\"%s\","
                             "nonce=\"%s\",uri=\"%s\",response=\"%s\","
                             "qop=\"auth\", cnonce=\"%s\", nc=%s%s",
                             hdr, parms->user, c->realm,
                             c->nonce, url->doc, digest,
                             cnonce, noncecount, options);
        } else {
                r = http_cmd(conn, "%s: Digest username=\"%s\",realm=\"%s\","
                             "nonce=\"%s\",uri=\"%s\",response=\"%s\"%s",
                             hdr, parms->user, c->realm,
                             c->nonce, url->doc, digest, options);
        }
        if (options)
                free(options);
        return (r);
}

/*
 * 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;

        DEBUGF("basic: usr: [%s]\n", usr);
        DEBUGF("basic: 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);
}

/*
 * Chose the challenge to answer and call the appropriate routine to
 * produce the header.
 */
static int
http_authorize(conn_t *conn, const char *hdr, http_auth_challenges_t *cs,
               http_auth_params_t *parms, struct url *url)
{
        http_auth_challenge_t *digest = NULL;
        int i;

        /* If user or pass are null we're not happy */
        if (!parms->user || !parms->password) {
                DEBUGF("NULL usr or pass\n");
                return (-1);
        }

        /* Look for a Digest */
        for (i = 0; i < cs->count; i++) {
                if (cs->challenges[i]->scheme == HTTPAS_DIGEST)
                        digest = cs->challenges[i];
        }

        /* Error if "Digest" was specified and there is no Digest challenge */
        if (!digest &&
            (parms->scheme && strcasecmp(parms->scheme, "digest") == 0)) {
                DEBUGF("Digest auth in env, not supported by peer\n");
                return (-1);
        }
        /*
         * If "basic" was specified in the environment, or there is no Digest
         * challenge, do the basic thing. Don't need a challenge for this,
         * so no need to check basic!=NULL
         */
        if (!digest ||
            (parms->scheme && strcasecmp(parms->scheme, "basic") == 0))
                return (http_basic_auth(conn,hdr,parms->user,parms->password));

        /* Else, prefer digest. We just checked that it's not NULL */
        return (http_digest_auth(conn, hdr, digest, parms, url));
}

/*****************************************************************************
 * 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)
{
        struct url *curl;
        conn_t *conn;
        hdr_t h;
        http_headerbuf_t headerbuf;
        const char *p;
        int verbose;
        int af, val;
        int serrno;
        bool isproxyauth = false;
        http_auth_challenges_t proxy_challenges;

#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

        curl = (purl != NULL) ? purl : URL;

retry:
        if ((conn = fetch_connect(curl->host, curl->port, af, verbose)) == NULL)
                /* fetch_connect() has already set an error code */
                return (NULL);
        init_http_headerbuf(&headerbuf);
        if (strcmp(URL->scheme, SCHEME_HTTPS) == 0 && purl) {
                init_http_auth_challenges(&proxy_challenges);
                http_cmd(conn, "CONNECT %s:%d HTTP/1.1", URL->host, URL->port);
                http_cmd(conn, "Host: %s:%d", URL->host, URL->port);
                if (isproxyauth) {
                        http_auth_params_t aparams;
                        init_http_auth_params(&aparams);
                        if (*purl->user || *purl->pwd) {
                                aparams.user = strdup(purl->user);
                                aparams.password = strdup(purl->pwd);
                        } else if ((p = getenv("HTTP_PROXY_AUTH")) != NULL &&
                                    *p != '\0') {
                                if (http_authfromenv(p, &aparams) < 0) {
                                        http_seterr(HTTP_NEED_PROXY_AUTH);
                                        fetch_syserr();
                                        goto ouch;
                                }
                        } else if (fetch_netrc_auth(purl) == 0) {
                                aparams.user = strdup(purl->user);
                                aparams.password = strdup(purl->pwd);
                        } else {
                                /*
                                 * No auth information found in system - exiting
                                 * with warning.
                                 */
                                warnx("Missing username and/or password set");
                                fetch_syserr();
                                goto ouch;
                        }
                        http_authorize(conn, "Proxy-Authorization",
                            &proxy_challenges, &aparams, purl);
                        clean_http_auth_params(&aparams);
                }
                http_cmd(conn, "");
                /* Get reply from CONNECT Tunnel attempt */
                int httpreply = http_get_reply(conn);
                if (httpreply != HTTP_OK) {
                        http_seterr(httpreply);
                        /* If the error is a 407/HTTP_NEED_PROXY_AUTH */
                        if (httpreply == HTTP_NEED_PROXY_AUTH &&
                            ! isproxyauth) {
                                /* Try again with authentication. */
                                clean_http_headerbuf(&headerbuf);
                                fetch_close(conn);
                                isproxyauth = true;
                                goto retry;
                        }
                        goto ouch;
                }
                /* Read and discard the rest of the proxy response */
                if (fetch_getln(conn) < 0) {
                        fetch_syserr();
                        goto ouch;
                }
                do {
                        switch ((h = http_next_header(conn, &headerbuf, &p))) {
                        case hdr_syserror:
                                fetch_syserr();
                                goto ouch;
                        case hdr_error:
                                http_seterr(HTTP_PROTOCOL_ERROR);
                                goto ouch;
                        default:
                                /* ignore */ ;
                        }
                } while (h > hdr_end);
        }
        if (strcmp(URL->scheme, SCHEME_HTTPS) == 0 &&
            fetch_ssl(conn, URL, verbose) == -1) {
                /* grrr */
                errno = EAUTH;
                fetch_syserr();
                goto ouch;
        }

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

        clean_http_headerbuf(&headerbuf);
        return (conn);
ouch:
        serrno = errno;
        clean_http_headerbuf(&headerbuf);
        fetch_close(conn);
        errno = serrno;
        return (NULL);
}

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

        if (flags != NULL && strchr(flags, 'd') != NULL)
                return (NULL);
        if (fetch_no_proxy_match(url->host))
                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 (strcmp(purl->scheme, SCHEME_HTTP) == 0)
                        return (purl);
                fetchFreeURL(purl);
        }
        return (NULL);
}

static void
http_print_html(FILE *out, FILE *in)
{
        ssize_t len = 0;
        size_t cap;
        char *line = NULL, *p, *q;
        int comment, tag;

        comment = tag = 0;
        while ((len = getline(&line, &cap, in)) >= 0) {
                while (len && isspace((unsigned char)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, q - p, 1, out);
                                tag = 1;
                                if (q + 3 < line + len &&
                                    strcmp(q, "<!--") == 0) {
                                        comment = 1;
                                        q += 3;
                                }
                        }
                }
                if (!tag && q > p)
                        fwrite(p, q - p, 1, out);
                fputc('\n', out);
        }

        free(line);
}


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

FILE *
http_request(struct url *URL, const char *op, struct url_stat *us,
        struct url *purl, const char *flags)
{

        return (http_request_body(URL, op, us, purl, flags, NULL, NULL));
}

/*
 * 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_body(struct url *URL, const char *op, struct url_stat *us,
        struct url *purl, const char *flags, const char *content_type,
        const char *body)
{
        char timebuf[80];
        char hbuf[MAXHOSTNAMELEN + 7], *host;
        conn_t *conn;
        struct url *url, *new;
        int chunked, direct, ims, noredirect, verbose;
        int e, i, n, val;
        off_t offset, clength, length, size;
        time_t mtime;
        const char *p;
        FILE *f;
        hdr_t h;
        struct tm *timestruct;
        http_headerbuf_t headerbuf;
        http_auth_challenges_t server_challenges;
        http_auth_challenges_t proxy_challenges;
        size_t body_len;

        /* The following calls don't allocate anything */
        init_http_headerbuf(&headerbuf);
        init_http_auth_challenges(&server_challenges);
        init_http_auth_challenges(&proxy_challenges);

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

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

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

        n = MAX_REDIRECT;
        i = 0;

        e = HTTP_PROTOCOL_ERROR;
        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;

                /* append port number only if necessary */
                host = url->host;
                if (url->port != fetch_default_port(url->scheme)) {
                        snprintf(hbuf, sizeof(hbuf), "%s:%d", host, url->port);
                        host = hbuf;
                }

                /* send request */
                if (verbose)
                        fetch_info("requesting %s://%s%s",
                            url->scheme, host, url->doc);
                if (purl && strcmp(url->scheme, SCHEME_HTTPS) != 0) {
                        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);
                }

                if (ims && url->ims_time) {
                        timestruct = gmtime((time_t *)&url->ims_time);
                        (void)strftime(timebuf, 80, "%a, %d %b %Y %T GMT",
                            timestruct);
                        if (verbose)
                                fetch_info("If-Modified-Since: %s", timebuf);
                        http_cmd(conn, "If-Modified-Since: %s", timebuf);
                }
                /* virtual host */
                http_cmd(conn, "Host: %s", host);

                /*
                 * Proxy authorization: we only send auth after we received
                 * a 407 error. We do not first try basic anyway (changed
                 * when support was added for digest-auth)
                 */
                if (purl && proxy_challenges.valid) {
                        http_auth_params_t aparams;
                        init_http_auth_params(&aparams);
                        if (*purl->user || *purl->pwd) {
                                aparams.user = strdup(purl->user);
                                aparams.password = strdup(purl->pwd);
                        } else if ((p = getenv("HTTP_PROXY_AUTH")) != NULL &&
                                   *p != '\0') {
                                if (http_authfromenv(p, &aparams) < 0) {
                                        http_seterr(HTTP_NEED_PROXY_AUTH);
                                        goto ouch;
                                }
                        } else if (fetch_netrc_auth(purl) == 0) {
                                aparams.user = strdup(purl->user);
                                aparams.password = strdup(purl->pwd);
                        }
                        http_authorize(conn, "Proxy-Authorization",
                                       &proxy_challenges, &aparams, url);
                        clean_http_auth_params(&aparams);
                }

                /*
                 * Server authorization: we never send "a priori"
                 * Basic auth, which used to be done if user/pass were
                 * set in the url. This would be weird because we'd send the
                 * password in the clear even if Digest is finally to be
                 * used (it would have made more sense for the
                 * pre-digest version to do this when Basic was specified
                 * in the environment)
                 */
                if (server_challenges.valid) {
                        http_auth_params_t aparams;
                        init_http_auth_params(&aparams);
                        if (*url->user || *url->pwd) {
                                aparams.user = strdup(url->user);
                                aparams.password = strdup(url->pwd);
                        } else if ((p = getenv("HTTP_AUTH")) != NULL &&
                                   *p != '\0') {
                                if (http_authfromenv(p, &aparams) < 0) {
                                        http_seterr(HTTP_NEED_AUTH);
                                        goto ouch;
                                }
                        } else if (fetch_netrc_auth(url) == 0) {
                                aparams.user = strdup(url->user);
                                aparams.password = strdup(url->pwd);
                        } else if (fetchAuthMethod &&
                                   fetchAuthMethod(url) == 0) {
                                aparams.user = strdup(url->user);
                                aparams.password = strdup(url->pwd);
                        } else {
                                http_seterr(HTTP_NEED_AUTH);
                                goto ouch;
                        }
                        http_authorize(conn, "Authorization",
                                       &server_challenges, &aparams, url);
                        clean_http_auth_params(&aparams);
                }

                /* other headers */
                if ((p = getenv("HTTP_ACCEPT")) != NULL) {
                        if (*p != '\0')
                                http_cmd(conn, "Accept: %s", p);
                } else {
                        http_cmd(conn, "Accept: */*");
                }
                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) {
                        /* no User-Agent if defined but empty */
                        if  (*p != '\0')
                                http_cmd(conn, "User-Agent: %s", p);
                } else {
                        /* default User-Agent */
                        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");

                if (body) {
                        body_len = strlen(body);
                        http_cmd(conn, "Content-Length: %zu", body_len);
                        if (content_type != NULL)
                                http_cmd(conn, "Content-Type: %s", content_type);
                }

                http_cmd(conn, "");

                if (body)
                        fetch_write(conn, body, body_len);

                /*
                 * 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;
                setsockopt(conn->sd, IPPROTO_TCP, TCP_NOPUSH, &val,
                           sizeof(val));
                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:
                case HTTP_NOT_MODIFIED:
                        /* fine */
                        break;
                case HTTP_MOVED_PERM:
                case HTTP_MOVED_TEMP:
                case HTTP_TEMP_REDIRECT:
                case HTTP_PERM_REDIRECT:
                case HTTP_SEE_OTHER:
                case HTTP_USE_PROXY:
                        /*
                         * Not so fine, but we still have to read the
                         * headers to get the new location.
                         */
                        break;
                case HTTP_NEED_AUTH:
                        if (server_challenges.valid) {
                                /*
                                 * 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 (proxy_challenges.valid) {
                                /*
                                 * We already sent our proxy
                                 * 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("proxy requires authorization");
                        break;
                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. http_next_header expects one line readahead */
                if (fetch_getln(conn) == -1) {
                        fetch_syserr();
                        goto ouch;
                }
                do {
                        switch ((h = http_next_header(conn, &headerbuf, &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 the A flag is set, we don't follow
                                 * temporary redirects.
                                 */
                                if (noredirect &&
                                    conn->err != HTTP_MOVED_PERM &&
                                    conn->err != HTTP_PERM_REDIRECT &&
                                    conn->err != HTTP_USE_PROXY) {
                                        n = 1;
                                        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 */
                                        DEBUGF("failed to parse new URL\n");
                                        goto ouch;
                                }

                                /* Only copy credentials if the host matches */
                                if (strcmp(new->host, url->host) == 0 &&
                                    !*new->user && !*new->pwd) {
                                        strcpy(new->user, url->user);
                                        strcpy(new->pwd, url->pwd);
                                }
                                new->offset = url->offset;
                                new->length = url->length;
                                new->ims_time = url->ims_time;
                                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 (http_parse_authenticate(p, &server_challenges) == 0)
                                        ++n;
                                break;
                        case hdr_proxy_authenticate:
                                if (conn->err != HTTP_NEED_PROXY_AUTH)
                                        break;
                                if (http_parse_authenticate(p, &proxy_challenges) == 0)
                                        ++n;
                                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 ||
                    conn->err == HTTP_NEED_PROXY_AUTH) {
                        e = conn->err;
                        if ((conn->err == HTTP_NEED_AUTH &&
                             !server_challenges.valid) ||
                            (conn->err == HTTP_NEED_PROXY_AUTH &&
                             !proxy_challenges.valid)) {
                                /* 401/7 but no www/proxy-authenticate ?? */
                                DEBUGF("%03d without auth header\n", conn->err);
                                goto ouch;
                        }
                        fetch_close(conn);
                        conn = NULL;
                        continue;
                }

                /* requested range not satisfiable */
                if (conn->err == HTTP_BAD_RANGE) {
                        if (url->offset > 0 && url->length == 0) {
                                /* asked for 0 bytes; fake it */
                                offset = url->offset;
                                clength = -1;
                                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_NOT_MODIFIED
                    || conn->err == HTTP_PARTIAL
                    || HTTP_ERROR(conn->err))
                        break;

                /* all other cases: we got a redirect */
                e = conn->err;
                clean_http_auth_challenges(&server_challenges);
                fetch_close(conn);
                conn = NULL;
                if (!new) {
                        DEBUGF("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;
        }

        DEBUGF("offset %lld, length %lld, size %lld, clength %lld\n",
            (long long)offset, (long long)length,
            (long long)size, (long long)clength);

        if (conn->err == HTTP_NOT_MODIFIED) {
                http_seterr(HTTP_NOT_MODIFIED);
                return (NULL);
        }

        /* 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 = 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;
        }
        clean_http_headerbuf(&headerbuf);
        clean_http_auth_challenges(&server_challenges);
        clean_http_auth_challenges(&proxy_challenges);
        return (f);

ouch:
        if (url != URL)
                fetchFreeURL(url);
        if (purl)
                fetchFreeURL(purl);
        if (conn != NULL)
                fetch_close(conn);
        clean_http_headerbuf(&headerbuf);
        clean_http_auth_challenges(&server_challenges);
        clean_http_auth_challenges(&proxy_challenges);
        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(URL, 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
 */
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(URL, flags), flags);
        if (f == NULL)
                return (-1);
        fclose(f);
        return (0);
}

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

/*
 * Arbitrary HTTP verb and content requests
 */
FILE *
fetchReqHTTP(struct url *URL, const char *method, const char *flags,
        const char *content_type, const char *body)
{

        return (http_request_body(URL, method, NULL, http_get_proxy(URL, flags),
            flags, content_type, body));
}