source: MondoRescue/branches/stable/mindi-busybox/networking/httpd.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * httpd implementation for busybox
 *
 * Copyright (C) 2002,2003 Glenn Engel <glenne@engel.org>
 * Copyright (C) 2003-2006 Vladimir Oleynik <dzo@simtreas.ru>
 *
 * simplify patch stolen from libbb without using strdup
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 *****************************************************************************
 *
 * Typical usage:
 *   for non root user
 * httpd -p 8080 -h $HOME/public_html
 *   or for daemon start from rc script with uid=0:
 * httpd -u www
 * This is equivalent if www user have uid=80 to
 * httpd -p 80 -u 80 -h /www -c /etc/httpd.conf -r "Web Server Authentication"
 *
 *
 * When a url starts by "/cgi-bin/" it is assumed to be a cgi script.  The
 * server changes directory to the location of the script and executes it
 * after setting QUERY_STRING and other environment variables.
 *
 * Doc:
 * "CGI Environment Variables": http://hoohoo.ncsa.uiuc.edu/cgi/env.html
 *
 * The server can also be invoked as a url arg decoder and html text encoder
 * as follows:
 *  foo=`httpd -d $foo`           # decode "Hello%20World" as "Hello World"
 *  bar=`httpd -e "<Hello World>"`  # encode as "&#60Hello&#32World&#62"
 * Note that url encoding for arguments is not the same as html encoding for
 * presentation.  -d decodes a url-encoded argument while -e encodes in html
 * for page display.
 *
 * httpd.conf has the following format:
 *
 * A:172.20.         # Allow address from 172.20.0.0/16
 * A:10.0.0.0/25     # Allow any address from 10.0.0.0-10.0.0.127
 * A:10.0.0.0/255.255.255.128  # Allow any address that previous set
 * A:127.0.0.1       # Allow local loopback connections
 * D:*               # Deny from other IP connections
 * E404:/path/e404.html # /path/e404.html is the 404 (not found) error page
 * /cgi-bin:foo:bar  # Require user foo, pwd bar on urls starting with /cgi-bin/
 * /adm:admin:setup  # Require user admin, pwd setup on urls starting with /adm/
 * /adm:toor:PaSsWd  # or user toor, pwd PaSsWd on urls starting with /adm/
 * .au:audio/basic   # additional mime type for audio.au files
 * *.php:/path/php   # running cgi.php scripts through an interpreter
 *
 * A/D may be as a/d or allow/deny - first char case insensitive
 * Deny IP rules take precedence over allow rules.
 *
 *
 * The Deny/Allow IP logic:
 *
 *  - Default is to allow all.  No addresses are denied unless
 *         denied with a D: rule.
 *  - Order of Deny/Allow rules is significant
 *  - Deny rules take precedence over allow rules.
 *  - If a deny all rule (D:*) is used it acts as a catch-all for unmatched
 *       addresses.
 *  - Specification of Allow all (A:*) is a no-op
 *
 * Example:
 *   1. Allow only specified addresses
 *     A:172.20          # Allow any address that begins with 172.20.
 *     A:10.10.          # Allow any address that begins with 10.10.
 *     A:127.0.0.1       # Allow local loopback connections
 *     D:*               # Deny from other IP connections
 *
 *   2. Only deny specified addresses
 *     D:1.2.3.        # deny from 1.2.3.0 - 1.2.3.255
 *     D:2.3.4.        # deny from 2.3.4.0 - 2.3.4.255
 *     A:*             # (optional line added for clarity)
 *
 * If a sub directory contains a config file it is parsed and merged with
 * any existing settings as if it was appended to the original configuration.
 *
 * subdir paths are relative to the containing subdir and thus cannot
 * affect the parent rules.
 *
 * Note that since the sub dir is parsed in the forked thread servicing the
 * subdir http request, any merge is discarded when the process exits.  As a
 * result, the subdir settings only have a lifetime of a single request.
 *
 * Custom error pages can contain an absolute path or be relative to
 * 'home_httpd'. Error pages are to be static files (no CGI or script). Error
 * page can only be defined in the root configuration file and are not taken
 * into account in local (directories) config files.
 *
 * If -c is not set, an attempt will be made to open the default
 * root configuration file.  If -c is set and the file is not found, the
 * server exits with an error.
 *
 */

#include "libbb.h"
#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
#include <sys/sendfile.h>
#endif

//#define DEBUG 1
#define DEBUG 0

/* amount of buffering in a pipe */
#ifndef PIPE_BUF
# define PIPE_BUF 4096
#endif

#define IOBUF_SIZE 8192    /* IO buffer */

#define HEADER_READ_TIMEOUT 60

static const char default_path_httpd_conf[] ALIGN1 = "/etc";
static const char httpd_conf[] ALIGN1 = "httpd.conf";
static const char HTTP_200[] ALIGN1 = "HTTP/1.0 200 OK\r\n";

typedef struct has_next_ptr {
    struct has_next_ptr *next;
} has_next_ptr;

/* Must have "next" as a first member */
typedef struct Htaccess {
    struct Htaccess *next;
    char *after_colon;
    char before_colon[1];  /* really bigger, must be last */
} Htaccess;

/* Must have "next" as a first member */
typedef struct Htaccess_IP {
    struct Htaccess_IP *next;
    unsigned ip;
    unsigned mask;
    int allow_deny;
} Htaccess_IP;

enum {
    HTTP_OK = 200,
    HTTP_MOVED_TEMPORARILY = 302,
    HTTP_BAD_REQUEST = 400,       /* malformed syntax */
    HTTP_UNAUTHORIZED = 401, /* authentication needed, respond with auth hdr */
    HTTP_NOT_FOUND = 404,
    HTTP_FORBIDDEN = 403,
    HTTP_REQUEST_TIMEOUT = 408,
    HTTP_NOT_IMPLEMENTED = 501,   /* used for unrecognized requests */
    HTTP_INTERNAL_SERVER_ERROR = 500,
    HTTP_CONTINUE = 100,
#if 0   /* future use */
    HTTP_SWITCHING_PROTOCOLS = 101,
    HTTP_CREATED = 201,
    HTTP_ACCEPTED = 202,
    HTTP_NON_AUTHORITATIVE_INFO = 203,
    HTTP_NO_CONTENT = 204,
    HTTP_MULTIPLE_CHOICES = 300,
    HTTP_MOVED_PERMANENTLY = 301,
    HTTP_NOT_MODIFIED = 304,
    HTTP_PAYMENT_REQUIRED = 402,
    HTTP_BAD_GATEWAY = 502,
    HTTP_SERVICE_UNAVAILABLE = 503, /* overload, maintenance */
    HTTP_RESPONSE_SETSIZE = 0xffffffff
#endif
};

static const uint16_t http_response_type[] ALIGN2 = {
    HTTP_OK,
    HTTP_MOVED_TEMPORARILY,
    HTTP_REQUEST_TIMEOUT,
    HTTP_NOT_IMPLEMENTED,
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH 
    HTTP_UNAUTHORIZED,
#endif
    HTTP_NOT_FOUND,
    HTTP_BAD_REQUEST,
    HTTP_FORBIDDEN,
    HTTP_INTERNAL_SERVER_ERROR,
#if 0   /* not implemented */
    HTTP_CREATED,
    HTTP_ACCEPTED,
    HTTP_NO_CONTENT,
    HTTP_MULTIPLE_CHOICES,
    HTTP_MOVED_PERMANENTLY,
    HTTP_NOT_MODIFIED,
    HTTP_BAD_GATEWAY,
    HTTP_SERVICE_UNAVAILABLE,
#endif
};

static const struct {
    const char *name;
    const char *info;
} http_response[ARRAY_SIZE(http_response_type)] = {
    { "OK", NULL },
    { "Found", "Directories must end with a slash" }, /* ?? */
    { "Request Timeout", "No request appeared within 60 seconds" },
    { "Not Implemented", "The requested method is not recognized" },
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    { "Unauthorized", "" },
#endif
    { "Not Found", "The requested URL was not found" },
    { "Bad Request", "Unsupported method" },
    { "Forbidden", ""  },
    { "Internal Server Error", "Internal Server Error" },
#if 0   /* not implemented */
    { "Created" },
    { "Accepted" },
    { "No Content" },
    { "Multiple Choices" },
    { "Moved Permanently" },
    { "Not Modified" },
    { "Bad Gateway", "" },
    { "Service Unavailable", "" },
#endif
};

struct globals {
    int verbose;            /* must be int (used by getopt32) */
    smallint flg_deny_all;

    unsigned rmt_ip;    /* used for IP-based allow/deny rules */
    time_t last_mod;
    off_t ContentLength;    /* -1 - unknown */
    char *rmt_ip_str;       /* for $REMOTE_ADDR and $REMOTE_PORT */
    const char *bind_addr_or_port;

    const char *g_query;
    const char *configFile;
    const char *home_httpd;

    const char *found_mime_type;
    const char *found_moved_temporarily;
    Htaccess_IP *ip_a_d;    /* config allow/deny lines */

    USE_FEATURE_HTTPD_BASIC_AUTH(const char *g_realm;)
    USE_FEATURE_HTTPD_BASIC_AUTH(char *remoteuser;)
    USE_FEATURE_HTTPD_CGI(char *referer;)
    USE_FEATURE_HTTPD_CGI(char *user_agent;)

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    Htaccess *g_auth;       /* config user:password lines */
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES
    Htaccess *mime_a;       /* config mime types */
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
    Htaccess *script_i;     /* config script interpreters */
#endif
    char *iobuf;            /* [IOBUF_SIZE] */
#define hdr_buf bb_common_bufsiz1
    char *hdr_ptr;
    int hdr_cnt;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
    const char *http_error_page[ARRAY_SIZE(http_response_type)];
#endif
};
#define G (*ptr_to_globals)
#define verbose           (G.verbose          )
#define flg_deny_all      (G.flg_deny_all     )
#define rmt_ip            (G.rmt_ip           )
#define bind_addr_or_port (G.bind_addr_or_port)
#define g_query           (G.g_query          )
#define configFile        (G.configFile       )
#define home_httpd        (G.home_httpd       )
#define found_mime_type   (G.found_mime_type  )
#define found_moved_temporarily (G.found_moved_temporarily)
#define ContentLength     (G.ContentLength    )
#define last_mod          (G.last_mod         )
#define ip_a_d            (G.ip_a_d           )
#define g_realm           (G.g_realm          )
#define remoteuser        (G.remoteuser       )
#define referer           (G.referer          )
#define user_agent        (G.user_agent       )
#define rmt_ip_str        (G.rmt_ip_str       )
#define g_auth            (G.g_auth           )
#define mime_a            (G.mime_a           )
#define script_i          (G.script_i         )
#define iobuf             (G.iobuf            )
#define hdr_ptr           (G.hdr_ptr          )
#define hdr_cnt           (G.hdr_cnt          )
#define http_error_page   (G.http_error_page  )
#define INIT_G() do { \
    PTR_TO_GLOBALS = xzalloc(sizeof(G)); \
    USE_FEATURE_HTTPD_BASIC_AUTH(g_realm = "Web Server Authentication";) \
    bind_addr_or_port = "80"; \
    ContentLength = -1; \
} while (0)


#define STRNCASECMP(a, str) strncasecmp((a), (str), sizeof(str)-1)

/* Prototypes */
static void send_file_and_exit(const char *url, int headers) ATTRIBUTE_NORETURN;

static void free_llist(has_next_ptr **pptr)
{
    has_next_ptr *cur = *pptr;
    while (cur) {
        has_next_ptr *t = cur;
        cur = cur->next;
        free(t);
    }
    *pptr = NULL;
}

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
static ALWAYS_INLINE void free_Htaccess_list(Htaccess **pptr)
{
    free_llist((has_next_ptr**)pptr);
}
#endif

static ALWAYS_INLINE void free_Htaccess_IP_list(Htaccess_IP **pptr)
{
    free_llist((has_next_ptr**)pptr);
}

/* Returns presumed mask width in bits or < 0 on error.
 * Updates strp, stores IP at provided pointer */
static int scan_ip(const char **strp, unsigned *ipp, unsigned char endc)
{
    const char *p = *strp;
    int auto_mask = 8;
    unsigned ip = 0;
    int j;

    if (*p == '/')
        return -auto_mask;

    for (j = 0; j < 4; j++) {
        unsigned octet;

        if ((*p < '0' || *p > '9') && *p != '/' && *p)
            return -auto_mask;
        octet = 0;
        while (*p >= '0' && *p <= '9') {
            octet *= 10;
            octet += *p - '0';
            if (octet > 255)
                return -auto_mask;
            p++;
        }
        if (*p == '.')
            p++;
        if (*p != '/' && *p)
            auto_mask += 8;
        ip = (ip << 8) | octet;
    }
    if (*p) {
        if (*p != endc)
            return -auto_mask;
        p++;
        if (*p == '\0')
            return -auto_mask;
    }
    *ipp = ip;
    *strp = p;
    return auto_mask;
}

/* Returns 0 on success. Stores IP and mask at provided pointers */
static int scan_ip_mask(const char *str, unsigned *ipp, unsigned *maskp)
{
    int i;
    unsigned mask;
    char *p;

    i = scan_ip(&str, ipp, '/');
    if (i < 0)
        return i;

    if (*str) {
        /* there is /xxx after dotted-IP address */
        i = bb_strtou(str, &p, 10);
        if (*p == '.') {
            /* 'xxx' itself is dotted-IP mask, parse it */
            /* (return 0 (success) only if it has N.N.N.N form) */
            return scan_ip(&str, maskp, '\0') - 32;
        }
        if (*p)
            return -1;
    }

    if (i > 32)
        return -1;

    if (sizeof(unsigned) == 4 && i == 32) {
        /* mask >>= 32 below may not work */
        mask = 0;
    } else {
        mask = 0xffffffff;
        mask >>= i;
    }
    /* i == 0 -> *maskp = 0x00000000
     * i == 1 -> *maskp = 0x80000000
     * i == 4 -> *maskp = 0xf0000000
     * i == 31 -> *maskp = 0xfffffffe
     * i == 32 -> *maskp = 0xffffffff */
    *maskp = (uint32_t)(~mask);
    return 0;
}

/*
 * Parse configuration file into in-memory linked list.
 *
 * The first non-white character is examined to determine if the config line
 * is one of the following:
 *    .ext:mime/type   # new mime type not compiled into httpd
 *    [adAD]:from      # ip address allow/deny, * for wildcard
 *    /path:user:pass  # username/password
 *    Ennn:error.html  # error page for status nnn
 *
 * Any previous IP rules are discarded.
 * If the flag argument is not SUBDIR_PARSE then all /path and mime rules
 * are also discarded.  That is, previous settings are retained if flag is
 * SUBDIR_PARSE.
 * Error pages are only parsed on the main config file.
 *
 * path   Path where to look for httpd.conf (without filename).
 * flag   Type of the parse request.
 */
/* flag */
#define FIRST_PARSE          0
#define SUBDIR_PARSE         1
#define SIGNALED_PARSE       2
#define FIND_FROM_HTTPD_ROOT 3
static void parse_conf(const char *path, int flag)
{
    FILE *f;
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    Htaccess *prev;
#endif
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
    Htaccess *cur;
#endif
    const char *cf = configFile;
    char buf[160];
    char *p0 = NULL;
    char *c, *p;
    Htaccess_IP *pip;

    /* discard old rules */
    free_Htaccess_IP_list(&ip_a_d);
    flg_deny_all = 0;
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
    /* retain previous auth and mime config only for subdir parse */
    if (flag != SUBDIR_PARSE) {
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        free_Htaccess_list(&g_auth);
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES
        free_Htaccess_list(&mime_a);
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
        free_Htaccess_list(&script_i);
#endif
    }
#endif

    if (flag == SUBDIR_PARSE || cf == NULL) {
        cf = alloca(strlen(path) + sizeof(httpd_conf) + 2);
        sprintf((char *)cf, "%s/%s", path, httpd_conf);
    }

    while ((f = fopen(cf, "r")) == NULL) {
        if (flag == SUBDIR_PARSE || flag == FIND_FROM_HTTPD_ROOT) {
            /* config file not found, no changes to config */
            return;
        }
        if (configFile && flag == FIRST_PARSE) /* if -c option given */
            bb_perror_msg_and_die("%s", cf);
        flag = FIND_FROM_HTTPD_ROOT;
        cf = httpd_conf;
    }

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    prev = g_auth;
#endif
    /* This could stand some work */
    while ((p0 = fgets(buf, sizeof(buf), f)) != NULL) {
        c = NULL;
        for (p = p0; *p0 != '\0' && *p0 != '#'; p0++) {
            if (!isspace(*p0)) {
                *p++ = *p0;
                if (*p0 == ':' && c == NULL)
                    c = p;
            }
        }
        *p = '\0';

        /* test for empty or strange line */
        if (c == NULL || *c == '\0')
            continue;
        p0 = buf;
        if (*p0 == 'd')
            *p0 = 'D';
        if (*c == '*') {
            if (*p0 == 'D') {
                /* memorize deny all */
                flg_deny_all = 1;
            }
            /* skip default other "word:*" config lines */
            continue;
        }

        if (*p0 == 'a')
            *p0 = 'A';
        if (*p0 == 'A' || *p0 == 'D') {
            /* storing current config IP line */
            pip = xzalloc(sizeof(Htaccess_IP));
            if (pip) {
                if (scan_ip_mask(c, &(pip->ip), &(pip->mask))) {
                    /* syntax IP{/mask} error detected, protect all */
                    *p0 = 'D';
                    pip->mask = 0;
                }
                pip->allow_deny = *p0;
                if (*p0 == 'D') {
                    /* Deny:from_IP move top */
                    pip->next = ip_a_d;
                    ip_a_d = pip;
                } else {
                    /* add to bottom A:form_IP config line */
                    Htaccess_IP *prev_IP = ip_a_d;

                    if (prev_IP == NULL) {
                        ip_a_d = pip;
                    } else {
                        while (prev_IP->next)
                            prev_IP = prev_IP->next;
                        prev_IP->next = pip;
                    }
                }
            }
            continue;
        }

#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
        if (flag == FIRST_PARSE && *p0 == 'E') {
            int i;
            /* error status code */
            int status = atoi(++p0);
            /* c already points at the character following ':' in parse loop */
            /* c = strchr(p0, ':'); c++; */
            if (status < HTTP_CONTINUE) {
                bb_error_msg("config error '%s' in '%s'", buf, cf);
                continue;
            }

            /* then error page; find matching status */
            for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
                if (http_response_type[i] == status) {
                    http_error_page[i] = concat_path_file((*c == '/') ? NULL : home_httpd, c);
                    break;
                }
            }
            continue;
        }
#endif

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
        if (*p0 == '/') {
            /* make full path from httpd root / current_path / config_line_path */
            cf = (flag == SUBDIR_PARSE ? path : "");
            p0 = xmalloc(strlen(cf) + (c - buf) + 2 + strlen(c));
            c[-1] = '\0';
            sprintf(p0, "/%s%s", cf, buf);

            /* another call bb_simplify_path */
            cf = p = p0;

            do {
                if (*p == '/') {
                    if (*cf == '/') {    /* skip duplicate (or initial) slash */
                        continue;
                    } else if (*cf == '.') {
                        if (cf[1] == '/' || cf[1] == '\0') { /* remove extra '.' */
                            continue;
                        } else if ((cf[1] == '.') && (cf[2] == '/' || cf[2] == '\0')) {
                            ++cf;
                            if (p > p0) {
                                while (*--p != '/') /* omit previous dir */;
                            }
                            continue;
                        }
                    }
                }
                *++p = *cf;
            } while (*++cf);

            if ((p == p0) || (*p != '/')) {      /* not a trailing slash */
                ++p;                             /* so keep last character */
            }
            *p = '\0';
            sprintf(p0 + strlen(p0), ":%s", c);
        }
#endif

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES \
 || ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
        /* storing current config line */
        cur = xzalloc(sizeof(Htaccess) + strlen(p0));
        if (cur) {
            cf = strcpy(cur->before_colon, p0);
            c = strchr(cf, ':');
            *c++ = 0;
            cur->after_colon = c;
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES
            if (*cf == '.') {
                /* config .mime line move top for overwrite previous */
                cur->next = mime_a;
                mime_a = cur;
                continue;
            }
#endif
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
            if (*cf == '*' && cf[1] == '.') {
                /* config script interpreter line move top for overwrite previous */
                cur->next = script_i;
                script_i = cur;
                continue;
            }
#endif
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
            free(p0);
            if (prev == NULL) {
                /* first line */
                g_auth = prev = cur;
            } else {
                /* sort path, if current lenght eq or bigger then move up */
                Htaccess *prev_hti = g_auth;
                size_t l = strlen(cf);
                Htaccess *hti;

                for (hti = prev_hti; hti; hti = hti->next) {
                    if (l >= strlen(hti->before_colon)) {
                        /* insert before hti */
                        cur->next = hti;
                        if (prev_hti != hti) {
                            prev_hti->next = cur;
                        } else {
                            /* insert as top */
                            g_auth = cur;
                        }
                        break;
                    }
                    if (prev_hti != hti)
                        prev_hti = prev_hti->next;
                }
                if (!hti) {       /* not inserted, add to bottom */
                    prev->next = cur;
                    prev = cur;
                }
            }
#endif
        }
#endif
     }
     fclose(f);
}

#if ENABLE_FEATURE_HTTPD_ENCODE_URL_STR
/*
 * Given a string, html-encode special characters.
 * This is used for the -e command line option to provide an easy way
 * for scripts to encode result data without confusing browsers.  The
 * returned string pointer is memory allocated by malloc().
 *
 * Returns a pointer to the encoded string (malloced).
 */
static char *encodeString(const char *string)
{
    /* take the simple route and encode everything */
    /* could possibly scan once to get length.     */
    int len = strlen(string);
    char *out = xmalloc(len * 6 + 1);
    char *p = out;
    char ch;

    while ((ch = *string++)) {
        /* very simple check for what to encode */
        if (isalnum(ch))
            *p++ = ch;
        else
            p += sprintf(p, "&#%d;", (unsigned char) ch);
    }
    *p = '\0';
    return out;
}
#endif          /* FEATURE_HTTPD_ENCODE_URL_STR */

/*
 * Given a URL encoded string, convert it to plain ascii.
 * Since decoding always makes strings smaller, the decode is done in-place.
 * Thus, callers should strdup() the argument if they do not want the
 * argument modified.  The return is the original pointer, allowing this
 * function to be easily used as arguments to other functions.
 *
 * string    The first string to decode.
 * option_d  1 if called for httpd -d
 *
 * Returns a pointer to the decoded string (same as input).
 */
static unsigned hex_to_bin(unsigned char c)
{
    unsigned v;

    v = c - '0';
    if (v <= 9)
        return v;
    /* c | 0x20: letters to lower case, non-letters
     * to (potentially different) non-letters */
    v = (unsigned)(c | 0x20) - 'a';
    if (v <= 5)
        return v + 10;
    return ~0;
}
/* For testing:
void t(char c) { printf("'%c'(%u) %u\n", c, c, hex_to_bin(c)); }
int main() { t(0x10); t(0x20); t('0'); t('9'); t('A'); t('F'); t('a'); t('f');
t('0'-1); t('9'+1); t('A'-1); t('F'+1); t('a'-1); t('f'+1); return 0; }
*/
static char *decodeString(char *orig, int option_d)
{
    /* note that decoded string is always shorter than original */
    char *string = orig;
    char *ptr = string;
    char c;

    while ((c = *ptr++) != '\0') {
        unsigned v;

        if (option_d && c == '+') {
            *string++ = ' ';
            continue;
        }
        if (c != '%') {
            *string++ = c;
            continue;
        }
        v = hex_to_bin(ptr[0]);
        if (v > 15) {
 bad_hex:
            if (!option_d)
                return NULL;
            *string++ = '%';
            continue;
        }
        v = (v * 16) | hex_to_bin(ptr[1]);
        if (v > 255)
            goto bad_hex;
        if (!option_d && (v == '/' || v == '\0')) {
            /* caller takes it as indication of invalid
             * (dangerous wrt exploits) chars */
            return orig + 1;
        }
        *string++ = v;
        ptr += 2;
    }
    *string = '\0';
    return orig;
}

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
/*
 * Decode a base64 data stream as per rfc1521.
 * Note that the rfc states that non base64 chars are to be ignored.
 * Since the decode always results in a shorter size than the input,
 * it is OK to pass the input arg as an output arg.
 * Parameter: a pointer to a base64 encoded string.
 * Decoded data is stored in-place.
 */
static void decodeBase64(char *Data)
{
    const unsigned char *in = (const unsigned char *)Data;
    /* The decoded size will be at most 3/4 the size of the encoded */
    unsigned ch = 0;
    int i = 0;

    while (*in) {
        int t = *in++;

        if (t >= '0' && t <= '9')
            t = t - '0' + 52;
        else if (t >= 'A' && t <= 'Z')
            t = t - 'A';
        else if (t >= 'a' && t <= 'z')
            t = t - 'a' + 26;
        else if (t == '+')
            t = 62;
        else if (t == '/')
            t = 63;
        else if (t == '=')
            t = 0;
        else
            continue;

        ch = (ch << 6) | t;
        i++;
        if (i == 4) {
            *Data++ = (char) (ch >> 16);
            *Data++ = (char) (ch >> 8);
            *Data++ = (char) ch;
            i = 0;
        }
    }
    *Data = '\0';
}
#endif

/*
 * Create a listen server socket on the designated port.
 */
static int openServer(void)
{
    int n = bb_strtou(bind_addr_or_port, NULL, 10);
    if (!errno && n && n <= 0xffff)
        n = create_and_bind_stream_or_die(NULL, n);
    else
        n = create_and_bind_stream_or_die(bind_addr_or_port, 80);
    xlisten(n, 9);
    return n;
}

/*
 * Log the connection closure and exit.
 */
static void log_and_exit(void) ATTRIBUTE_NORETURN;
static void log_and_exit(void)
{
    /* Paranoia. IE said to be buggy. It may send some extra data
     * or be confused by us just exiting without SHUT_WR. Oh well. */
    shutdown(1, SHUT_WR);
    ndelay_on(0);
    while (read(0, iobuf, IOBUF_SIZE) > 0)
        continue;

    if (verbose > 2)
        bb_error_msg("closed");
    _exit(xfunc_error_retval);
}

/*
 * Create and send HTTP response headers.
 * The arguments are combined and sent as one write operation.  Note that
 * IE will puke big-time if the headers are not sent in one packet and the
 * second packet is delayed for any reason.
 * responseNum - the result code to send.
 */
static void send_headers(int responseNum)
{
    static const char RFC1123FMT[] ALIGN1 = "%a, %d %b %Y %H:%M:%S GMT";

    const char *responseString = "";
    const char *infoString = NULL;
    const char *mime_type;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
    const char *error_page = 0;
#endif
    unsigned i;
    time_t timer = time(0);
    char tmp_str[80];
    int len;

    for (i = 0; i < ARRAY_SIZE(http_response_type); i++) {
        if (http_response_type[i] == responseNum) {
            responseString = http_response[i].name;
            infoString = http_response[i].info;
#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
            error_page = http_error_page[i];
#endif
            break;
        }
    }
    /* error message is HTML */
    mime_type = responseNum == HTTP_OK ?
                found_mime_type : "text/html";

    if (verbose)
        bb_error_msg("response:%u", responseNum);

    /* emit the current date */
    strftime(tmp_str, sizeof(tmp_str), RFC1123FMT, gmtime(&timer));
    len = sprintf(iobuf,
            "HTTP/1.0 %d %s\r\nContent-type: %s\r\n"
            "Date: %s\r\nConnection: close\r\n",
            responseNum, responseString, mime_type, tmp_str);

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    if (responseNum == HTTP_UNAUTHORIZED) {
        len += sprintf(iobuf + len,
                "WWW-Authenticate: Basic realm=\"%s\"\r\n",
                g_realm);
    }
#endif
    if (responseNum == HTTP_MOVED_TEMPORARILY) {
        len += sprintf(iobuf + len, "Location: %s/%s%s\r\n",
                found_moved_temporarily,
                (g_query ? "?" : ""),
                (g_query ? g_query : ""));
    }

#if ENABLE_FEATURE_HTTPD_ERROR_PAGES
    if (error_page && !access(error_page, R_OK)) {
        strcat(iobuf, "\r\n");
        len += 2;

        if (DEBUG)
            fprintf(stderr, "headers: '%s'\n", iobuf);
        full_write(1, iobuf, len);
        if (DEBUG)
            fprintf(stderr, "writing error page: '%s'\n", error_page);
        return send_file_and_exit(error_page, FALSE);
    }
#endif

    if (ContentLength != -1) {    /* file */
        strftime(tmp_str, sizeof(tmp_str), RFC1123FMT, gmtime(&last_mod));
        len += sprintf(iobuf + len, "Last-Modified: %s\r\n%s %"OFF_FMT"d\r\n",
            tmp_str, "Content-length:", ContentLength);
    }
    iobuf[len++] = '\r';
    iobuf[len++] = '\n';
    if (infoString) {
        len += sprintf(iobuf + len,
                "<HTML><HEAD><TITLE>%d %s</TITLE></HEAD>\n"
                "<BODY><H1>%d %s</H1>\n%s\n</BODY></HTML>\n",
                responseNum, responseString,
                responseNum, responseString, infoString);
    }
    if (DEBUG)
        fprintf(stderr, "headers: '%s'\n", iobuf);
    if (full_write(1, iobuf, len) != len) {
        if (verbose > 1)
            bb_perror_msg("error");
        log_and_exit();
    }
}

static void send_headers_and_exit(int responseNum) ATTRIBUTE_NORETURN;
static void send_headers_and_exit(int responseNum)
{
    send_headers(responseNum);
    log_and_exit();
}

/*
 * Read from the socket until '\n' or EOF. '\r' chars are removed.
 * '\n' is replaced with NUL.
 * Return number of characters read or 0 if nothing is read
 * ('\r' and '\n' are not counted).
 * Data is returned in iobuf.
 */
static int get_line(void)
{
    int count = 0;
    char c;

    while (1) {
        if (hdr_cnt <= 0) {
            hdr_cnt = safe_read(0, hdr_buf, sizeof(hdr_buf));
            if (hdr_cnt <= 0)
                break;
            hdr_ptr = hdr_buf;
        }
        iobuf[count] = c = *hdr_ptr++;
        hdr_cnt--;

        if (c == '\r')
            continue;
        if (c == '\n') {
            iobuf[count] = '\0';
            return count;
        }
        if (count < (IOBUF_SIZE - 1))      /* check overflow */
            count++;
    }
    return count;
}

#if ENABLE_FEATURE_HTTPD_CGI
static void setenv1(const char *name, const char *value)
{
    setenv(name, value ? value : "", 1);
}

/*
 * Spawn CGI script, forward CGI's stdin/out <=> network
 *
 * Environment variables are set up and the script is invoked with pipes
 * for stdin/stdout.  If a post is being done the script is fed the POST
 * data in addition to setting the QUERY_STRING variable (for GETs or POSTs).
 *
 * Parameters:
 * const char *url              The requested URL (with leading /).
 * int bodyLen                  Length of the post body.
 * const char *cookie           For set HTTP_COOKIE.
 * const char *content_type     For set CONTENT_TYPE.
 */
static void send_cgi_and_exit(
        const char *url,
        const char *request,
        int bodyLen,
        const char *cookie,
        const char *content_type) ATTRIBUTE_NORETURN;
static void send_cgi_and_exit(
        const char *url,
        const char *request,
        int bodyLen,
        const char *cookie,
        const char *content_type)
{
    struct { int rd; int wr; } fromCgi;  /* CGI -> httpd pipe */
    struct { int rd; int wr; } toCgi;    /* httpd -> CGI pipe */
    char *fullpath;
    char *script;
    char *purl;
    int buf_count;
    int status;
    int pid = 0;

    /*
     * We are mucking with environment _first_ and then vfork/exec,
     * this allows us to use vfork safely. Parent don't care about
     * these environment changes anyway.
     */

    /*
     * Find PATH_INFO.
     */
    purl = xstrdup(url);
    script = purl;
    while ((script = strchr(script + 1, '/')) != NULL) {
        /* have script.cgi/PATH_INFO or dirs/script.cgi[/PATH_INFO] */
        struct stat sb;

        *script = '\0';
        if (!is_directory(purl + 1, 1, &sb)) {
            /* not directory, found script.cgi/PATH_INFO */
            *script = '/';
            break;
        }
        *script = '/';          /* is directory, find next '/' */
    }
    setenv1("PATH_INFO", script);   /* set /PATH_INFO or "" */
    setenv1("REQUEST_METHOD", request);
    if (g_query) {
        putenv(xasprintf("%s=%s?%s", "REQUEST_URI", purl, g_query));
    } else {
        setenv1("REQUEST_URI", purl);
    }
    if (script != NULL)
        *script = '\0';         /* cut off /PATH_INFO */

    /* SCRIPT_FILENAME required by PHP in CGI mode */
    fullpath = concat_path_file(home_httpd, purl);
    setenv1("SCRIPT_FILENAME", fullpath);
    /* set SCRIPT_NAME as full path: /cgi-bin/dirs/script.cgi */
    setenv1("SCRIPT_NAME", purl);
    /* http://hoohoo.ncsa.uiuc.edu/cgi/env.html:
     * QUERY_STRING: The information which follows the ? in the URL
     * which referenced this script. This is the query information.
     * It should not be decoded in any fashion. This variable
     * should always be set when there is query information,
     * regardless of command line decoding. */
    /* (Older versions of bbox seem to do some decoding) */
    setenv1("QUERY_STRING", g_query);
    putenv((char*)"SERVER_SOFTWARE=busybox httpd/"BB_VER);
    putenv((char*)"SERVER_PROTOCOL=HTTP/1.0");
    putenv((char*)"GATEWAY_INTERFACE=CGI/1.1");
    /* Having _separate_ variables for IP and port defeats
     * the purpose of having socket abstraction. Which "port"
     * are you using on Unix domain socket?
     * IOW - REMOTE_PEER="1.2.3.4:56" makes much more sense.
     * Oh well... */
    {
        char *p = rmt_ip_str ? rmt_ip_str : (char*)"";
        char *cp = strrchr(p, ':');
        if (ENABLE_FEATURE_IPV6 && cp && strchr(cp, ']'))
            cp = NULL;
        if (cp) *cp = '\0'; /* delete :PORT */
        setenv1("REMOTE_ADDR", p);
        if (cp) {
            *cp = ':';
#if ENABLE_FEATURE_HTTPD_SET_REMOTE_PORT_TO_ENV
            setenv1("REMOTE_PORT", cp + 1);
#endif
        }
    }
    setenv1("HTTP_USER_AGENT", user_agent);
    if (bodyLen)
        putenv(xasprintf("CONTENT_LENGTH=%d", bodyLen));
    if (cookie)
        setenv1("HTTP_COOKIE", cookie);
    if (content_type)
        setenv1("CONTENT_TYPE", content_type);
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    if (remoteuser) {
        setenv1("REMOTE_USER", remoteuser);
        putenv((char*)"AUTH_TYPE=Basic");
    }
#endif
    if (referer)
        setenv1("HTTP_REFERER", referer);

    xpipe(&fromCgi.rd);
    xpipe(&toCgi.rd);

    pid = vfork();
    if (pid < 0) {
        /* TODO: log perror? */
        log_and_exit();
    }

    if (!pid) {
        /* Child process */
        xfunc_error_retval = 242;

        xmove_fd(toCgi.rd, 0);  /* replace stdin with the pipe */
        xmove_fd(fromCgi.wr, 1);  /* replace stdout with the pipe */
        close(fromCgi.rd);
        close(toCgi.wr);
        /* User seeing stderr output can be a security problem.
         * If CGI really wants that, it can always do dup itself. */
        /* dup2(1, 2); */

        /* script must have absolute path */
        script = strrchr(fullpath, '/');
        if (!script)
            goto error_execing_cgi;
        *script = '\0';
        /* chdiring to script's dir */
        if (chdir(fullpath) == 0) {
            char *argv[2];
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
            char *interpr = NULL;
            char *suffix = strrchr(purl, '.');

            if (suffix) {
                Htaccess *cur;
                for (cur = script_i; cur; cur = cur->next) {
                    if (strcmp(cur->before_colon + 1, suffix) == 0) {
                        interpr = cur->after_colon;
                        break;
                    }
                }
            }
#endif
            *script = '/';
            /* set argv[0] to name without path */
            argv[0] = (char*)bb_basename(purl);
            argv[1] = NULL;
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
            if (interpr)
                execv(interpr, argv);
            else
#endif
                execv(fullpath, argv);
        }
 error_execing_cgi:
        /* send to stdout
         * (we are CGI here, our stdout is pumped to the net) */
        send_headers_and_exit(HTTP_NOT_FOUND);
    } /* end child */

    /* Parent process */

    /* First, restore variables possibly changed by child */
    xfunc_error_retval = 0;

    /* Prepare for pumping data.
     * iobuf is used for CGI -> network data,
     * hdr_buf is for network -> CGI data (POSTDATA) */
    buf_count = 0;
    close(fromCgi.wr);
    close(toCgi.rd);

    /* If CGI dies, we still want to correctly finish reading its output
     * and send it to the peer. So please no SIGPIPEs! */
    signal(SIGPIPE, SIG_IGN);

    /* This loop still looks messy. What is an exit criteria?
     * "CGI's output closed"? Or "CGI has exited"?
     * What to do if CGI has closed both input and output, but
     * didn't exit? etc... */

    /* NB: breaking out of this loop jumps to log_and_exit() */
    while (1) {
        fd_set readSet;
        fd_set writeSet;
        int nfound;
        int count;

        FD_ZERO(&readSet);
        FD_ZERO(&writeSet);
        FD_SET(fromCgi.rd, &readSet);
        if (bodyLen > 0 || hdr_cnt > 0) {
            FD_SET(toCgi.wr, &writeSet);
            nfound = toCgi.wr > fromCgi.rd ? toCgi.wr : fromCgi.rd;
            if (hdr_cnt <= 0)
                FD_SET(0, &readSet);
            /* Now wait on the set of sockets! */
            nfound = select(nfound + 1, &readSet, &writeSet, NULL, NULL);
        } else {
            if (!bodyLen) {
                close(toCgi.wr); /* no more POST data to CGI */
                bodyLen = -1;
            }
            nfound = select(fromCgi.rd + 1, &readSet, NULL, NULL, NULL);
        }

        if (nfound <= 0) {
            if (waitpid(pid, &status, WNOHANG) <= 0) {
                /* Weird. CGI didn't exit and no fd's
                 * are ready, yet select returned?! */
                continue;
            }
            close(fromCgi.rd);
            if (DEBUG && WIFEXITED(status))
                bb_error_msg("CGI exited, status=%d", WEXITSTATUS(status));
            if (DEBUG && WIFSIGNALED(status))
                bb_error_msg("CGI killed, signal=%d", WTERMSIG(status));
            break;
        }

        if (hdr_cnt > 0 && FD_ISSET(toCgi.wr, &writeSet)) {
            /* Have data from peer and can write to CGI */
            count = safe_write(toCgi.wr, hdr_ptr, hdr_cnt);
            /* Doesn't happen, we dont use nonblocking IO here
             *if (count < 0 && errno == EAGAIN) {
             *  ...
             *} else */
            if (count > 0) {
                hdr_ptr += count;
                hdr_cnt -= count;
            } else {
                hdr_cnt = bodyLen = 0; /* EOF/broken pipe to CGI */
            }
        } else if (bodyLen > 0 && hdr_cnt == 0
         && FD_ISSET(0, &readSet)
        ) {
            /* We expect data, prev data portion is eaten by CGI
             * and there *is* data to read from the peer
             * (POSTDATA?) */
            count = bodyLen > (int)sizeof(hdr_buf) ? (int)sizeof(hdr_buf) : bodyLen;
            count = safe_read(0, hdr_buf, count);
            if (count > 0) {
                hdr_cnt = count;
                hdr_ptr = hdr_buf;
                bodyLen -= count;
            } else {
                bodyLen = 0; /* closed */
            }
        }

#define PIPESIZE PIPE_BUF
#if PIPESIZE >= IOBUF_SIZE
# error "PIPESIZE >= IOBUF_SIZE"
#endif
        if (FD_ISSET(fromCgi.rd, &readSet)) {
            /* There is something to read from CGI */
            char *rbuf = iobuf;

            /* Are we still buffering CGI output? */
            if (buf_count >= 0) {
                /* HTTP_200[] has single "\r\n" at the end.
                 * According to http://hoohoo.ncsa.uiuc.edu/cgi/out.html,
                 * CGI scripts MUST send their own header terminated by
                 * empty line, then data. That's why we have only one
                 * <cr><lf> pair here. We will output "200 OK" line
                 * if needed, but CGI still has to provide blank line
                 * between header and body */

                /* Must use safe_read, not full_read, because
                 * CGI may output a few first bytes and then wait
                 * for POSTDATA without closing stdout.
                 * With full_read we may wait here forever. */
                count = safe_read(fromCgi.rd, rbuf + buf_count, PIPESIZE - 8);
                if (count <= 0) {
                    /* eof (or error) and there was no "HTTP",
                     * so write it, then write received data */
                    if (buf_count) {
                        full_write(1, HTTP_200, sizeof(HTTP_200)-1);
                        full_write(1, rbuf, buf_count);
                    }
                    break; /* CGI stdout is closed, exiting */
                }
                buf_count += count;
                count = 0;
                /* "Status" header format is: "Status: 302 Redirected\r\n" */
                if (buf_count >= 8 && memcmp(rbuf, "Status: ", 8) == 0) {
                    /* send "HTTP/1.0 " */
                    if (full_write(1, HTTP_200, 9) != 9)
                        break;
                    rbuf += 8; /* skip "Status: " */
                    count = buf_count - 8;
                    buf_count = -1; /* buffering off */
                } else if (buf_count >= 4) {
                    /* Did CGI add "HTTP"? */
                    if (memcmp(rbuf, HTTP_200, 4) != 0) {
                        /* there is no "HTTP", do it ourself */
                        if (full_write(1, HTTP_200, sizeof(HTTP_200)-1) != sizeof(HTTP_200)-1)
                            break;
                    }
                    /* Commented out:
                    if (!strstr(rbuf, "ontent-")) {
                        full_write(s, "Content-type: text/plain\r\n\r\n", 28);
                    }
                     * Counter-example of valid CGI without Content-type:
                     * echo -en "HTTP/1.0 302 Found\r\n"
                     * echo -en "Location: http://www.busybox.net\r\n"
                     * echo -en "\r\n"
                     */
                    count = buf_count;
                    buf_count = -1; /* buffering off */
                }
            } else {
                count = safe_read(fromCgi.rd, rbuf, PIPESIZE);
                if (count <= 0)
                    break;  /* eof (or error) */
            }
            if (full_write(1, rbuf, count) != count)
                break;
            if (DEBUG)
                fprintf(stderr, "cgi read %d bytes: '%.*s'\n", count, count, rbuf);
        } /* if (FD_ISSET(fromCgi.rd)) */
    } /* while (1) */
    log_and_exit();
}
#endif          /* FEATURE_HTTPD_CGI */

/*
 * Send a file response to a HTTP request, and exit
 * 
 * Parameters:
 * const char *url    The requested URL (with leading /).
 * headers            Don't send headers before if FALSE.
 */
static void send_file_and_exit(const char *url, int headers)
{
    static const char *const suffixTable[] = {
    /* Warning: shorter equivalent suffix in one line must be first */
        ".htm.html", "text/html",
        ".jpg.jpeg", "image/jpeg",
        ".gif",      "image/gif",
        ".png",      "image/png",
        ".txt.h.c.cc.cpp", "text/plain",
        ".css",      "text/css",
        ".wav",      "audio/wav",
        ".avi",      "video/x-msvideo",
        ".qt.mov",   "video/quicktime",
        ".mpe.mpeg", "video/mpeg",
        ".mid.midi", "audio/midi",
        ".mp3",      "audio/mpeg",
#if 0                        /* unpopular */
        ".au",       "audio/basic",
        ".pac",      "application/x-ns-proxy-autoconfig",
        ".vrml.wrl", "model/vrml",
#endif
        NULL
    };

    char *suffix;
    int f;
    const char *const *table;
    const char *try_suffix;
    ssize_t count;
#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
    off_t offset = 0;
#endif

    suffix = strrchr(url, '.');

    /* If not found, set default as "application/octet-stream";  */
    found_mime_type = "application/octet-stream";
    if (suffix) {
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES
        Htaccess *cur;
#endif
        for (table = suffixTable; *table; table += 2) {
            try_suffix = strstr(table[0], suffix);
            if (try_suffix) {
                try_suffix += strlen(suffix);
                if (*try_suffix == '\0' || *try_suffix == '.') {
                    found_mime_type = table[1];
                    break;
                }
            }
        }
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_MIME_TYPES
        for (cur = mime_a; cur; cur = cur->next) {
            if (strcmp(cur->before_colon, suffix) == 0) {
                found_mime_type = cur->after_colon;
                break;
            }
        }
#endif
    }

    if (DEBUG)
        bb_error_msg("sending file '%s' content-type: %s",
            url, found_mime_type);

    f = open(url, O_RDONLY);
    if (f < 0) {
        if (DEBUG)
            bb_perror_msg("cannot open '%s'", url);
        if (headers)
            send_headers_and_exit(HTTP_NOT_FOUND);
    }

    if (headers)
        send_headers(HTTP_OK);

    /* If you want to know about EPIPE below
     * (happens if you abort downloads from local httpd): */
    signal(SIGPIPE, SIG_IGN);

#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
    do {
        /* byte count (3rd arg) is rounded down to 64k */
        count = sendfile(1, f, &offset, MAXINT(ssize_t) - 0xffff);
        if (count < 0) {
            if (offset == 0)
                goto fallback;
            goto fin;
        }
    } while (count > 0);
    log_and_exit();

 fallback:
#endif
    while ((count = safe_read(f, iobuf, IOBUF_SIZE)) > 0) {
        ssize_t n = count;
        count = full_write(1, iobuf, count);
        if (count != n)
            break;
    }
#if ENABLE_FEATURE_HTTPD_USE_SENDFILE
 fin:
#endif
    if (count < 0 && verbose > 1)
        bb_perror_msg("error");
    log_and_exit();
}

static int checkPermIP(void)
{
    Htaccess_IP *cur;

    /* This could stand some work */
    for (cur = ip_a_d; cur; cur = cur->next) {
#if DEBUG
        fprintf(stderr,
            "checkPermIP: '%s' ? '%u.%u.%u.%u/%u.%u.%u.%u'\n",
            rmt_ip_str,
            (unsigned char)(cur->ip >> 24),
            (unsigned char)(cur->ip >> 16),
            (unsigned char)(cur->ip >> 8),
            (unsigned char)(cur->ip),
            (unsigned char)(cur->mask >> 24),
            (unsigned char)(cur->mask >> 16),
            (unsigned char)(cur->mask >> 8),
            (unsigned char)(cur->mask)
        );
#endif
        if ((rmt_ip & cur->mask) == cur->ip)
            return cur->allow_deny == 'A';   /* Allow/Deny */
    }

    /* if unconfigured, return 1 - access from all */
    return !flg_deny_all;
}

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
/*
 * Check the permission file for access password protected.
 *
 * If config file isn't present, everything is allowed.
 * Entries are of the form you can see example from header source
 *
 * path      The file path.
 * request   User information to validate.
 *
 * Returns 1 if request is OK.
 */
static int checkPerm(const char *path, const char *request)
{
    Htaccess *cur;
    const char *p;
    const char *p0;

    const char *prev = NULL;

    /* This could stand some work */
    for (cur = g_auth; cur; cur = cur->next) {
        size_t l;

        p0 = cur->before_colon;
        if (prev != NULL && strcmp(prev, p0) != 0)
            continue;       /* find next identical */
        p = cur->after_colon;
        if (DEBUG)
            fprintf(stderr, "checkPerm: '%s' ? '%s'\n", p0, request);

        l = strlen(p0);
        if (strncmp(p0, path, l) == 0
         && (l == 1 || path[l] == '/' || path[l] == '\0')
        ) {
            char *u;
            /* path match found.  Check request */
            /* for check next /path:user:password */
            prev = p0;
            u = strchr(request, ':');
            if (u == NULL) {
                /* bad request, ':' required */
                break;
            }

            if (ENABLE_FEATURE_HTTPD_AUTH_MD5) {
                char *cipher;
                char *pp;

                if (strncmp(p, request, u - request) != 0) {
                    /* user doesn't match */
                    continue;
                }
                pp = strchr(p, ':');
                if (pp && pp[1] == '$' && pp[2] == '1'
                 && pp[3] == '$' && pp[4]
                ) {
                    pp++;
                    cipher = pw_encrypt(u+1, pp);
                    if (strcmp(cipher, pp) == 0)
                        goto set_remoteuser_var;   /* Ok */
                    /* unauthorized */
                    continue;
                }
            }

            if (strcmp(p, request) == 0) {
 set_remoteuser_var:
                remoteuser = strdup(request);
                if (remoteuser)
                    remoteuser[u - request] = '\0';
                return 1;   /* Ok */
            }
            /* unauthorized */
        }
    } /* for */

    return prev == NULL;
}
#endif  /* FEATURE_HTTPD_BASIC_AUTH */

/*
 * Handle timeouts
 */
static void exit_on_signal(int sig) ATTRIBUTE_NORETURN;
static void exit_on_signal(int sig)
{
    send_headers_and_exit(HTTP_REQUEST_TIMEOUT);
}

/*
 * Handle an incoming http request and exit.
 */
static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr) ATTRIBUTE_NORETURN;
static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
{
    static const char request_GET[] ALIGN1 = "GET";

    struct stat sb;
    char *urlcopy;
    char *urlp;
    char *tptr;
    int http_major_version;
    int ip_allowed;
#if ENABLE_FEATURE_HTTPD_CGI
    const char *prequest;
    unsigned long length = 0;
    char *cookie = 0;
    char *content_type = 0;
#endif
    struct sigaction sa;
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    int credentials = -1;  /* if not required this is Ok */
#endif

    /* Allocation of iobuf is postponed until now
     * (IOW, server process doesn't need to waste 8k) */
    iobuf = xmalloc(IOBUF_SIZE);

    rmt_ip = 0;
    if (fromAddr->sa.sa_family == AF_INET) {
        rmt_ip = ntohl(fromAddr->sin.sin_addr.s_addr);
    }
#if ENABLE_FEATURE_IPV6
    if (fromAddr->sa.sa_family == AF_INET6
     && fromAddr->sin6.sin6_addr.s6_addr32[0] == 0
     && fromAddr->sin6.sin6_addr.s6_addr32[1] == 0
     && ntohl(fromAddr->sin6.sin6_addr.s6_addr32[2]) == 0xffff)
        rmt_ip = ntohl(fromAddr->sin6.sin6_addr.s6_addr32[3]);
#endif
    if (ENABLE_FEATURE_HTTPD_CGI || DEBUG || verbose) {
        rmt_ip_str = xmalloc_sockaddr2dotted(&fromAddr->sa);
    }
    if (verbose) {
        /* this trick makes -v logging much simpler */
        applet_name = rmt_ip_str;
        if (verbose > 2)
            bb_error_msg("connected");
    }

    /* Install timeout handler */
    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = exit_on_signal;
    /* sigemptyset(&sa.sa_mask); - memset should be enough */
    /*sa.sa_flags = 0; - no SA_RESTART */
    sigaction(SIGALRM, &sa, NULL);
    alarm(HEADER_READ_TIMEOUT);

    if (!get_line()) /* EOF or error or empty line */
        send_headers_and_exit(HTTP_BAD_REQUEST);

    /* Determine type of request (GET/POST) */
    urlp = strpbrk(iobuf, " \t");
    if (urlp == NULL)
        send_headers_and_exit(HTTP_BAD_REQUEST);
    *urlp++ = '\0';
#if ENABLE_FEATURE_HTTPD_CGI
    prequest = request_GET;
    if (strcasecmp(iobuf, prequest) != 0) {
        prequest = "POST";
        if (strcasecmp(iobuf, prequest) != 0)
            send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
    }
#else
    if (strcasecmp(iobuf, request_GET) != 0)
        send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
#endif
    urlp = skip_whitespace(urlp);
    if (urlp[0] != '/')
        send_headers_and_exit(HTTP_BAD_REQUEST);

    /* Find end of URL and parse HTTP version, if any */
    http_major_version = -1;
    tptr = strchrnul(urlp, ' ');
    /* Is it " HTTP/"? */
    if (tptr[0] && strncmp(tptr + 1, HTTP_200, 5) == 0)
        http_major_version = (tptr[6] - '0');
    *tptr = '\0';

    /* Copy URL from after "GET "/"POST " to stack-allocated char[] */
    urlcopy = alloca((tptr - urlp) + sizeof("/index.html"));
    /*if (urlcopy == NULL)
     *  send_headers_and_exit(HTTP_INTERNAL_SERVER_ERROR);*/
    strcpy(urlcopy, urlp);
    /* NB: urlcopy ptr is never changed after this */

    /* Extract url args if present */
    tptr = strchr(urlcopy, '?');
    g_query = NULL;
    if (tptr) {
        *tptr++ = '\0';
        g_query = tptr;
    }

    /* Decode URL escape sequences */
    tptr = decodeString(urlcopy, 0);
    if (tptr == NULL)
        send_headers_and_exit(HTTP_BAD_REQUEST);
    if (tptr == urlcopy + 1) {
        /* '/' or NUL is encoded */
        send_headers_and_exit(HTTP_NOT_FOUND);
    }

    /* Canonicalize path */
    /* Algorithm stolen from libbb bb_simplify_path(),
     * but don't strdup and reducing trailing slash and protect out root */
    urlp = tptr = urlcopy;
    do {
        if (*urlp == '/') {
            /* skip duplicate (or initial) slash */
            if (*tptr == '/') {
                continue;
            }
            if (*tptr == '.') {
                /* skip extra '.' */
                if (tptr[1] == '/' || !tptr[1]) {
                    continue;
                }
                /* '..': be careful */
                if (tptr[1] == '.' && (tptr[2] == '/' || !tptr[2])) {
                    ++tptr;
                    if (urlp == urlcopy) /* protect root */
                        send_headers_and_exit(HTTP_BAD_REQUEST);
                    while (*--urlp != '/') /* omit previous dir */;
                        continue;
                }
            }
        }
        *++urlp = *tptr;
    } while (*++tptr);
    *++urlp = '\0';       /* so keep last character */
    tptr = urlp;          /* end ptr */

    /* If URL is a directory, add '/' */
    if (tptr[-1] != '/') {
        if (is_directory(urlcopy + 1, 1, &sb)) {
            found_moved_temporarily = urlcopy;
        }
    }

    /* Log it */
    if (verbose > 1)
        bb_error_msg("url:%s", urlcopy);

    tptr = urlcopy;
    ip_allowed = checkPermIP();
    while (ip_allowed && (tptr = strchr(tptr + 1, '/')) != NULL) {
        /* have path1/path2 */
        *tptr = '\0';
        if (is_directory(urlcopy + 1, 1, &sb)) {
            /* may be having subdir config */
            parse_conf(urlcopy + 1, SUBDIR_PARSE);
            ip_allowed = checkPermIP();
        }
        *tptr = '/';
    }
    if (http_major_version >= 0) {
        /* Request was with "... HTTP/nXXX", and n >= 0 */

        /* Read until blank line for HTTP version specified, else parse immediate */
        while (1) {
            alarm(HEADER_READ_TIMEOUT);
            if (!get_line())
                break; /* EOF or error or empty line */
            if (DEBUG)
                bb_error_msg("header: '%s'", iobuf);

#if ENABLE_FEATURE_HTTPD_CGI
            /* try and do our best to parse more lines */
            if ((STRNCASECMP(iobuf, "Content-length:") == 0)) {
                /* extra read only for POST */
                if (prequest != request_GET) {
                    tptr = iobuf + sizeof("Content-length:") - 1;
                    if (!tptr[0])
                        send_headers_and_exit(HTTP_BAD_REQUEST);
                    errno = 0;
                    /* not using strtoul: it ignores leading minus! */
                    length = strtol(tptr, &tptr, 10);
                    /* length is "ulong", but we need to pass it to int later */
                    /* so we check for negative or too large values in one go: */
                    /* (long -> ulong conv caused negatives to be seen as > INT_MAX) */
                    if (tptr[0] || errno || length > INT_MAX)
                        send_headers_and_exit(HTTP_BAD_REQUEST);
                }
            } else if (STRNCASECMP(iobuf, "Cookie:") == 0) {
                cookie = strdup(skip_whitespace(iobuf + sizeof("Cookie:")-1));
            } else if (STRNCASECMP(iobuf, "Content-Type:") == 0) {
                content_type = strdup(skip_whitespace(iobuf + sizeof("Content-Type:")-1));
            } else if (STRNCASECMP(iobuf, "Referer:") == 0) {
                referer = strdup(skip_whitespace(iobuf + sizeof("Referer:")-1));
            } else if (STRNCASECMP(iobuf, "User-Agent:") == 0) {
                user_agent = strdup(skip_whitespace(iobuf + sizeof("User-Agent:")-1));
            }
#endif
#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
            if (STRNCASECMP(iobuf, "Authorization:") == 0) {
                /* We only allow Basic credentials.
                 * It shows up as "Authorization: Basic <userid:password>" where
                 * the userid:password is base64 encoded.
                 */
                tptr = skip_whitespace(iobuf + sizeof("Authorization:")-1);
                if (STRNCASECMP(tptr, "Basic") != 0)
                    continue;
                tptr += sizeof("Basic")-1;
                /* decodeBase64() skips whitespace itself */
                decodeBase64(tptr);
                credentials = checkPerm(urlcopy, tptr);
            }
#endif          /* FEATURE_HTTPD_BASIC_AUTH */
        } /* while extra header reading */
    }

    /* We read headers, disable peer timeout */
    alarm(0);

    if (strcmp(bb_basename(urlcopy), httpd_conf) == 0 || ip_allowed == 0) {
        /* protect listing [/path]/httpd_conf or IP deny */
        send_headers_and_exit(HTTP_FORBIDDEN);
    }

#if ENABLE_FEATURE_HTTPD_BASIC_AUTH
    if (credentials <= 0 && checkPerm(urlcopy, ":") == 0) {
        send_headers_and_exit(HTTP_UNAUTHORIZED);
    }
#endif

    if (found_moved_temporarily) {
        send_headers_and_exit(HTTP_MOVED_TEMPORARILY);
    }

    tptr = urlcopy + 1;      /* skip first '/' */

#if ENABLE_FEATURE_HTTPD_CGI
    if (strncmp(tptr, "cgi-bin/", 8) == 0) {
        if (tptr[8] == '\0') {
            /* protect listing "cgi-bin/" */
            send_headers_and_exit(HTTP_FORBIDDEN);
        }
        send_cgi_and_exit(urlcopy, prequest, length, cookie, content_type);
    }
#if ENABLE_FEATURE_HTTPD_CONFIG_WITH_SCRIPT_INTERPR
    {
        char *suffix = strrchr(tptr, '.');
        if (suffix) {
            Htaccess *cur;
            for (cur = script_i; cur; cur = cur->next) {
                if (strcmp(cur->before_colon + 1, suffix) == 0) {
                    send_cgi_and_exit(urlcopy, prequest, length, cookie, content_type);
                }
            }
        }
    }
#endif
    if (prequest != request_GET) {
        send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
    }
#endif  /* FEATURE_HTTPD_CGI */

    if (urlp[-1] == '/')
        strcpy(urlp, "index.html");
    if (stat(tptr, &sb) == 0) {
        /* It's a dir URL and there is index.html */
        ContentLength = sb.st_size;
        last_mod = sb.st_mtime;
    }
#if ENABLE_FEATURE_HTTPD_CGI
    else if (urlp[-1] == '/') {
        /* It's a dir URL and there is no index.html
         * Try cgi-bin/index.cgi */
        if (access("/cgi-bin/index.cgi"+1, X_OK) == 0) {
            urlp[0] = '\0';
            g_query = urlcopy;
            send_cgi_and_exit("/cgi-bin/index.cgi", prequest, length, cookie, content_type);
        }
    }
#endif
    /* else {
     *  fall through to send_file, it errors out if open fails
     * }
     */

    send_file_and_exit(tptr, TRUE);
}

/*
 * The main http server function.
 * Given a socket, listen for new connections and farm out
 * the processing as a [v]forked process.
 * Never returns.
 */
#if BB_MMU
static void mini_httpd(int server_socket) ATTRIBUTE_NORETURN;
static void mini_httpd(int server_socket)
{
    /* NB: it's best to not use xfuncs in this loop before fork().
     * Otherwise server may die on transient errors (temporary
     * out-of-memory condition, etc), which is Bad(tm).
     * Try to do any dangerous calls after fork.
     */
    while (1) {
        int n;
        len_and_sockaddr fromAddr;
        
        /* Wait for connections... */
        fromAddr.len = LSA_SIZEOF_SA;
        n = accept(server_socket, &fromAddr.sa, &fromAddr.len);

        if (n < 0)
            continue;
        /* set the KEEPALIVE option to cull dead connections */
        setsockopt(n, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));

        if (fork() == 0) {
            /* child */
#if ENABLE_FEATURE_HTTPD_RELOAD_CONFIG_SIGHUP
            /* Do not reload config on HUP */
            signal(SIGHUP, SIG_IGN);
#endif
            close(server_socket);
            xmove_fd(n, 0);
            xdup2(0, 1);

            handle_incoming_and_exit(&fromAddr);
        }
        /* parent, or fork failed */
        close(n);
    } /* while (1) */
    /* never reached */
}
#else
static void mini_httpd_nommu(int server_socket, int argc, char **argv) ATTRIBUTE_NORETURN;
static void mini_httpd_nommu(int server_socket, int argc, char **argv)
{
    char *argv_copy[argc + 2];

    argv_copy[0] = argv[0];
    argv_copy[1] = (char*)"-i";
    memcpy(&argv_copy[2], &argv[1], argc * sizeof(argv[0]));

    /* NB: it's best to not use xfuncs in this loop before vfork().
     * Otherwise server may die on transient errors (temporary
     * out-of-memory condition, etc), which is Bad(tm).
     * Try to do any dangerous calls after fork.
     */
    while (1) {
        int n;
        len_and_sockaddr fromAddr;
        
        /* Wait for connections... */
        fromAddr.len = LSA_SIZEOF_SA;
        n = accept(server_socket, &fromAddr.sa, &fromAddr.len);

        if (n < 0)
            continue;
        /* set the KEEPALIVE option to cull dead connections */
        setsockopt(n, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));

        if (vfork() == 0) {
            /* child */
#if ENABLE_FEATURE_HTTPD_RELOAD_CONFIG_SIGHUP
            /* Do not reload config on HUP */
            signal(SIGHUP, SIG_IGN);
#endif
            close(server_socket);
            xmove_fd(n, 0);
            xdup2(0, 1);

            /* Run a copy of ourself in inetd mode */
            re_exec(argv_copy);
        }
        /* parent, or vfork failed */
        close(n);
    } /* while (1) */
    /* never reached */
}
#endif

/*
 * Process a HTTP connection on stdin/out.
 * Never returns.
 */
static void mini_httpd_inetd(void) ATTRIBUTE_NORETURN;
static void mini_httpd_inetd(void)
{
    len_and_sockaddr fromAddr;

    fromAddr.len = LSA_SIZEOF_SA;
    getpeername(0, &fromAddr.sa, &fromAddr.len);
    handle_incoming_and_exit(&fromAddr);
}

#if ENABLE_FEATURE_HTTPD_RELOAD_CONFIG_SIGHUP
static void sighup_handler(int sig)
{
    struct sigaction sa;

    parse_conf(default_path_httpd_conf, sig == SIGHUP ? SIGNALED_PARSE : FIRST_PARSE);

    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = sighup_handler;
    /*sigemptyset(&sa.sa_mask); - memset should be enough */
    sa.sa_flags = SA_RESTART;
    sigaction(SIGHUP, &sa, NULL);
}
#endif

enum {
    c_opt_config_file = 0,
    d_opt_decode_url,
    h_opt_home_httpd,
    USE_FEATURE_HTTPD_ENCODE_URL_STR(e_opt_encode_url,)
    USE_FEATURE_HTTPD_BASIC_AUTH(    r_opt_realm     ,)
    USE_FEATURE_HTTPD_AUTH_MD5(      m_opt_md5       ,)
    USE_FEATURE_HTTPD_SETUID(        u_opt_setuid    ,)
    p_opt_port      ,
    p_opt_inetd     ,
    p_opt_foreground,
    p_opt_verbose   ,
    OPT_CONFIG_FILE = 1 << c_opt_config_file,
    OPT_DECODE_URL  = 1 << d_opt_decode_url,
    OPT_HOME_HTTPD  = 1 << h_opt_home_httpd,
    OPT_ENCODE_URL  = USE_FEATURE_HTTPD_ENCODE_URL_STR((1 << e_opt_encode_url)) + 0,
    OPT_REALM       = USE_FEATURE_HTTPD_BASIC_AUTH(    (1 << r_opt_realm     )) + 0,
    OPT_MD5         = USE_FEATURE_HTTPD_AUTH_MD5(      (1 << m_opt_md5       )) + 0,
    OPT_SETUID      = USE_FEATURE_HTTPD_SETUID(        (1 << u_opt_setuid    )) + 0,
    OPT_PORT        = 1 << p_opt_port,
    OPT_INETD       = 1 << p_opt_inetd,
    OPT_FOREGROUND  = 1 << p_opt_foreground,
    OPT_VERBOSE     = 1 << p_opt_verbose,
};


int httpd_main(int argc, char **argv);
int httpd_main(int argc, char **argv)
{
    int server_socket = server_socket; /* for gcc */
    unsigned opt;
    char *url_for_decode;
    USE_FEATURE_HTTPD_ENCODE_URL_STR(const char *url_for_encode;)
    USE_FEATURE_HTTPD_SETUID(const char *s_ugid = NULL;)
    USE_FEATURE_HTTPD_SETUID(struct bb_uidgid_t ugid;)
    USE_FEATURE_HTTPD_AUTH_MD5(const char *pass;)

    INIT_G();

#if ENABLE_LOCALE_SUPPORT
    /* Undo busybox.c: we want to speak English in http (dates etc) */
    setlocale(LC_TIME, "C");
#endif

    home_httpd = xrealloc_getcwd_or_warn(NULL);
    /* -v counts, -i implies -f */
    opt_complementary = "vv:if";
    /* We do not "absolutize" path given by -h (home) opt.
     * If user gives relative path in -h, $SCRIPT_FILENAME can end up
     * relative too. */
    opt = getopt32(argv, "c:d:h:"
            USE_FEATURE_HTTPD_ENCODE_URL_STR("e:")
            USE_FEATURE_HTTPD_BASIC_AUTH("r:")
            USE_FEATURE_HTTPD_AUTH_MD5("m:")
            USE_FEATURE_HTTPD_SETUID("u:")
            "p:ifv",
            &configFile, &url_for_decode, &home_httpd
            USE_FEATURE_HTTPD_ENCODE_URL_STR(, &url_for_encode)
            USE_FEATURE_HTTPD_BASIC_AUTH(, &g_realm)
            USE_FEATURE_HTTPD_AUTH_MD5(, &pass)
            USE_FEATURE_HTTPD_SETUID(, &s_ugid)
            , &bind_addr_or_port
            , &verbose
        );
    if (opt & OPT_DECODE_URL) {
        fputs(decodeString(url_for_decode, 1), stdout);
        return 0;
    }
#if ENABLE_FEATURE_HTTPD_ENCODE_URL_STR
    if (opt & OPT_ENCODE_URL) {
        fputs(encodeString(url_for_encode), stdout);
        return 0;
    }
#endif
#if ENABLE_FEATURE_HTTPD_AUTH_MD5
    if (opt & OPT_MD5) {
        puts(pw_encrypt(pass, "$1$"));
        return 0;
    }
#endif
#if ENABLE_FEATURE_HTTPD_SETUID
    if (opt & OPT_SETUID) {
        if (!get_uidgid(&ugid, s_ugid, 1))
            bb_error_msg_and_die("unrecognized user[:group] "
                        "name '%s'", s_ugid);
    }
#endif

#if !BB_MMU
    if (!(opt & OPT_FOREGROUND)) {
        bb_daemonize_or_rexec(0, argv); /* don't change current directory */
    }
#endif

    xchdir(home_httpd);
    if (!(opt & OPT_INETD)) {
        signal(SIGCHLD, SIG_IGN);
        server_socket = openServer();
#if ENABLE_FEATURE_HTTPD_SETUID
        /* drop privileges */
        if (opt & OPT_SETUID) {
            if (ugid.gid != (gid_t)-1) {
                if (setgroups(1, &ugid.gid) == -1)
                    bb_perror_msg_and_die("setgroups");
                xsetgid(ugid.gid);
            }
            xsetuid(ugid.uid);
        }
#endif
    }

#if ENABLE_FEATURE_HTTPD_CGI
    {
        char *p = getenv("PATH");
        /* env strings themself are not freed, no need to strdup(p): */
        clearenv();
        if (p)
            putenv(p - 5);
//      if (!(opt & OPT_INETD))
//          setenv_long("SERVER_PORT", ???);
    }
#endif

#if ENABLE_FEATURE_HTTPD_RELOAD_CONFIG_SIGHUP
    if (!(opt & OPT_INETD))
        sighup_handler(0);
    else /* do not install HUP handler in inetd mode */
#endif
        parse_conf(default_path_httpd_conf, FIRST_PARSE);

    xfunc_error_retval = 0;
    if (opt & OPT_INETD)
        mini_httpd_inetd();
#if BB_MMU
    if (!(opt & OPT_FOREGROUND))
        bb_daemonize(0); /* don't change current directory */
    mini_httpd(server_socket); /* never returns */
#else
    mini_httpd_nommu(server_socket, argc, argv); /* never returns */
#endif
    /* return 0; */
}