/*
 * Copyright (c) 2004, Nate Nielsen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above
 *       copyright notice, this list of conditions and the
 *       following disclaimer.
 *     * 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.
 *     * The names of contributors to this software may not be
 *       used to endorse or promote products derived from this
 *       software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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
 * COPYRIGHT OWNER OR CONTRIBUTORS 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.
 *
 *
 * CONTRIBUTORS
 *  Nate Nielsen <nielsen@memberwebs.com>
 *
 */

#include <httpd.h>
#include <http_core.h>
#include <http_config.h>
#include <http_log.h>
#include <http_protocol.h>
#include <ap_config.h>
#include <apr_strings.h>
#include <apr_lib.h>

#include <unistd.h>

#include "sock_any.h"
#include "stringx.h"

#define DEFAULT_PORT 8020

module AP_MODULE_DECLARE_DATA httpauth_module;

/* Keep track of a unique identifier */
static void* conn_current = NULL;

/* And increment this when it goes out of scope */
static unsigned int conn_seen = 0;

typedef struct httpauth_context
{
    const char* socketname;
    int socket;
    int types;
    const char* handler;
    const char* domain;
    apr_pool_t* child_pool;
}
httpauth_context_t;

/* TODO: Support proxy authentication properly */

#define AUTH_PREFIX_BASIC   "Basic"
#define AUTH_PREFIX_DIGEST  "Digest"
#define AUTH_PREFIX_NTLM    "NTLM"

#define AUTH_TYPE_BASIC     1 << 1
#define AUTH_TYPE_DIGEST    1 << 2
#define AUTH_TYPE_NTLM      1 << 3
#define AUTH_TYPE_ANY       0x0000FFFF

#define HTTPAUTH_AUTHTYPE   "HTTPAUTH"

/* -------------------------------------------------------------------------------
 * Configuration code
 */

static void* httpauth_dir_config(apr_pool_t* p, char* dir)
{
    httpauth_context_t* ctx;

    ctx = (httpauth_context_t*)apr_pcalloc(p, sizeof(*ctx));
    memset(ctx, 0, sizeof(*ctx));

    ctx->socket = -1;
    ctx->types = 0xFFFFFFFF;
    ctx->child_pool = p;
    return ctx;
}

static const char* set_socket(cmd_parms* cmd, void* config, const char* val)
{
    struct sockaddr_any sany;

    if(sock_any_pton(val, &sany, DEFAULT_PORT) == -1)
        return "Invalid socket name or ip in HttpAuthSocket";

    ((httpauth_context_t*)config)->socketname = val;
    return NULL;
}

static const char* set_handler(cmd_parms* cmd, void* config, const char* val)
{
    httpauth_context_t* conf = (httpauth_context_t*)config;
    conf->handler = val;
    return NULL;
}

static const char* set_types(cmd_parms* cmd, void* config, const char* val)
{
    httpauth_context_t* conf = (httpauth_context_t*)config;
    int type = 0;

    if(strcasecmp(val, AUTH_PREFIX_BASIC) == 0)
        type = AUTH_TYPE_BASIC;
    else if(strcasecmp(val, AUTH_PREFIX_DIGEST) == 0)
        type = AUTH_TYPE_DIGEST;
    else if(strcasecmp(val, AUTH_PREFIX_NTLM) == 0)
        type = AUTH_TYPE_NTLM;
    else if(strcasecmp(val, "any"))
        type = AUTH_TYPE_ANY;
    else
        return "Invalid type in HttpAuthTypes";

    if(conf->types == 0xFFFFFFFF)
        conf->types = type;
    else
        conf->types |= type;

    return NULL;
}

static const char* set_domain(cmd_parms* cmd, void* config, const char* val)
{
    httpauth_context_t* conf = (httpauth_context_t*)config;
    conf->domain = trim_space(apr_pstrdup(cmd->pool, val));
    return NULL;
}

static const command_rec httpauth_cmds[] =
{
    AP_INIT_TAKE1( "HttpAuthSocket", set_socket, NULL, OR_AUTHCFG,
      "The socket that httpauthd is listening on" ),
    AP_INIT_TAKE1( "HttpAuthHandler", set_handler, NULL, OR_AUTHCFG,
      "The handler that httpauthd should use to authenticate" ),
    AP_INIT_ITERATE( "HttpAuthTypes", set_types, NULL, OR_AUTHCFG,
      "The types of authentiction allowed (Basic, Digest, NTLM ...)" ),
    AP_INIT_RAW_ARGS( "HttpAuthDigestDomain", set_domain, NULL, OR_AUTHCFG,
      "The domain for which digest authentication is relevant" ),
    { NULL }
};

/* -------------------------------------------------------------------------------
 * Socket handling code
 */

static apr_status_t cleanup_socket(void *fdv)
{
	close((int)(long)fdv);
	return OK;
}

void disconnect_socket(httpauth_context_t* ctx, server_rec* s)
{
    if(ctx->socket != -1)
    {
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                     "httpauth: disconnecting from daemon");

		apr_pool_cleanup_kill(ctx->child_pool, (void*)(long)ctx->socket,
						      cleanup_socket);
        close(ctx->socket);
        ctx->socket = -1;
    }
}

void read_junk(httpauth_context_t* ctx, request_rec* r)
{
    char buf[16];
    const char* t;
    int said = 0;
    int l;

    if(ctx->socket == -1)
        return;

    /* Make it non blocking */
    fcntl(ctx->socket, F_SETFL, fcntl(ctx->socket, F_GETFL, 0) | O_NONBLOCK);

    for(;;)
    {
        l = read(ctx->socket, buf, sizeof(buf) - 1);
        if(l <= 0)
            break;

        buf[l] = 0;
        t = trim_start(buf);

        if(!said && *t)
        {
            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r,
                          "httpauth: received junk data from daemon");
            said = 1;
        }
    }

    fcntl(ctx->socket, F_SETFL, fcntl(ctx->socket, F_GETFL, 0) & ~O_NONBLOCK);
}

int read_line(httpauth_context_t* ctx, request_rec* r, char** line)
{
    int l;
    int al = 128;
    char* t;
    const char* e;

    e = t = NULL;
    *line = NULL;

    for(;;)
    {
        if(!*line || t + 2 == e)
        {
            char* n;
            int d;

            n = (char*)apr_palloc(r->pool, al * 2);

            if(*line)
                memcpy(n, *line, al);

            al *= 2;

            /* The difference */
            d = t - *line;

            *line = n;
            t = n + d;
            e = n + al;
        }

        l = read(ctx->socket, (void*)t, sizeof(char));

        /* We got a character */
        if(l == 1)
        {
            /* Skip junky CRLFs */
            if(*t == '\r')
            {
                *t = ' ';
                continue;
            }

            /* End of line */
            else if(*t == '\n')
            {
                t++;
                break;
            }

            t++;
        }

        /* If it's the end of file then return that */
        else if(l == 0)
        {
			/* Disconnect from socket quietly so we can reconnect later */
			disconnect_socket(ctx, r->server);
            return -1;
        }

        /* Transient errors */
        else if(l == -1 && errno == EAGAIN)
            continue;

        /* Fatal errors */
        else if(l == -1)
        {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, APR_FROM_OS_ERROR(errno), r,
                          "httpauth: couldn't read data from daemon");
            return -1;
        }
    }

    *t = 0;
    return 0;
}

int read_response(httpauth_context_t* ctx, request_rec* r,
                  int* code, int* ccode, char** details)
{
    int c;
    char* line;
    char* t;
    char* t2;

    if(read_line(ctx, r, &line) == -1)
        return -1;

    line = trim_space(line);

    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                  "httpauth: received response line from daemon: %s", line);

    /* Get response code */
    t = ap_getword_nc(r->pool, &line, ' ');
    c = strtol(t, &t2, 10);
    if(*t2 || c < 100 || c > 999)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "httpauth: protocol error: invalid code: %s", t);
        return -1;
    }

    if(code)
        *code = c;

    if(c >= 400)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "httpauth: received error from httpauthd: %d %s", c, line);
        return -1;
    }

    /* Get the second response code if we're a 200 */
    if(c == 200)
    {
        t = ap_getword_nc(r->pool, &line, ' ');
        c = strtol(t, &t2, 10);
        if(*t2 || c < 100 || c > 999)
        {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "httpauth: protocol error: invalid code: %s", t);
            return -1;
        }

        if(ccode)
            *ccode = c;
    }

    if(details)
        *details = trim_space(line);

    return 0;
}

int read_copy_headers(httpauth_context_t* ctx, int ccode, request_rec* r)
{
    char* line;
    const char* name;
    apr_table_t* headers;
    int c = 0;

    if(ccode > 299)
        headers = r->err_headers_out;
    else
        headers = r->headers_out;

    for(;;)
    {
        if(read_line(ctx, r, &line) == -1)
            return -1;

        /* If that's it then break */
        if(!*line)
            break;

        if(apr_isspace(*line))
        {
            line = (char*)trim_start(line);

            /* End of headers */
            if(!*line)
                break;

            if(c > 0)
            {
                /*
                 * TODO: We really should be supporting headers split
                 * across lines. But httpauthd doesn't currently produce
                 * headers like that, so we don't need to care about it.
                 */
                ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r,
                              "httpauth: protocol error: server sent us an split header, which we don't support.");
            }
            else
            {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                              "httpauth: protocol error: invalid headers.");
            }
        }

        name = ap_getword_nc(r->pool, &line, ':');
        if(!name || !*name)
            break;

        /*
         * If that was the end of the line, then it's an
         * invalid header :(
         */
        if(!*line)
        {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "httpauth: protocol header: invalid headers");
            return -1;
        }

        line = trim_space(line);

        if(strcasecmp(name, "WWW-Authenticate") == 0)
        {
            if(strncasecmp(line, AUTH_PREFIX_BASIC, strlen(AUTH_PREFIX_BASIC)) == 0 &&
               !(ctx->types & AUTH_TYPE_BASIC))
                continue;

            else if(strncasecmp(line, AUTH_PREFIX_DIGEST, strlen(AUTH_PREFIX_DIGEST)) == 0 &&
                    !(ctx->types & AUTH_TYPE_DIGEST))
                continue;

            /* Only allow unknown if we don't have it */
            else if(!(ctx->types & AUTH_TYPE_ANY))
                continue;

            /* Fix up when we're a proxy */
            if(r->proxyreq == PROXYREQ_PROXY)
                name = "Proxy-Authenticate";
        }

        else if(strcasecmp(name, "Authentication-Info") == 0)
        {
            if(r->proxyreq == PROXYREQ_PROXY)
                name = "Proxy-Authentication-Info";
        }

        c++;
        apr_table_addn(headers, name, line);
    }

    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                  "httpauth: received %d headers from daemon", c);

    return 0;
}

int write_data(httpauth_context_t* ctx, server_rec* s, const char* data)
{
    int r;

    if(ctx->socket == -1)
    {
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                     "httpauth: Socket to httpauthd daemon closed. Can't write data.");
        return -1;
    }

    while(*data != 0)
    {
        r = write(ctx->socket, data, strlen(data));

        if(r > 0)
            data += r;

        else if(r == -1)
        {
            if(errno == EAGAIN)
                continue;

            /* The other end closed. no message */
            if(errno == EPIPE)
                disconnect_socket(ctx, s);

            else
                ap_log_error(APLOG_MARK, APLOG_ERR, APR_FROM_OS_ERROR(errno), s,
                             "httpauth: Couldn't write data to daemon");

            return -1;
        }
    }

    return 0;
}

int connect_socket(httpauth_context_t* ctx, request_rec* r)
{
    struct sockaddr_any sany;
    int ret = -1;

    disconnect_socket(ctx, r->server);

    if(sock_any_pton(ctx->socketname, &sany, DEFAULT_PORT) == -1)
    {
        ap_log_rerror(APLOG_MARK, APLOG_CRIT, 0, r,
                      "httpauth: Invalid socket name or ip.");
        goto finally;
    }

	ctx->socket = socket(SANY_TYPE(sany), SOCK_STREAM, 0);
    if(ctx->socket == -1)
    {
        ap_log_rerror(APLOG_MARK, APLOG_CRIT, APR_FROM_OS_ERROR(errno), r,
                      "httpauth: Can't create socket: %s", ctx->socketname);
        goto finally;
    }

	apr_pool_cleanup_register(ctx->child_pool, (void*)(long)ctx->socket,
						      cleanup_socket, cleanup_socket);

    if(connect(ctx->socket, &SANY_ADDR(sany), SANY_LEN(sany)) != 0)
    {
        ap_log_rerror(APLOG_MARK, APLOG_CRIT, APR_FROM_OS_ERROR(errno), r,
                      "httpauth: Can't connect to httpauthd");
        goto finally;
    }

    ret = 0;

finally:
    if(ret == -1)
        disconnect_socket(ctx, r->server);

    errno = 0;
    return ret;
}

int connect_httpauth(httpauth_context_t* ctx, request_rec* r)
{
    int ret = -1;
    int code;
    char* details;
    const char* t;

    if(connect_socket(ctx, r) == -1)
        goto finally;

    if(read_response(ctx, r, &code, NULL, &details) == -1)
        goto finally;

    if(code != 100)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "httpauth: protocol error (Expected 100, got %d)", code);
        goto finally;
    }

    /* Check theversion number */
    details = trim_space(details);

    if(strcmp(details, "HTTPAUTH/1.0") != 0)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "httpauth: Daemon speaking incompatible protocol version: %s", details);
        goto finally;
    }

    /* Send our handler */
    if(ctx->handler)
    {
        t = apr_pstrcat(r->pool, "SET Handler ", ctx->handler, "\n", NULL);

        if(write_data(ctx, r->server, t) == -1)
            goto finally;

        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                      "httpauth: sent handler to daemon: %s", t);

        if(read_response(ctx, r, &code, NULL, NULL) == -1)
            goto finally;

        if(code != 202)
        {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "httpauth: protocol error (Expected 202, got %d)", code);
            goto finally;
        }
    }

    /* Send any setup info we have */
    if(ctx->domain)
    {
        t = apr_pstrcat(r->pool, "SET Domain ", ctx->domain, "\n", NULL);

        if(write_data(ctx, r->server, t) == -1)
            goto finally;

        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                      "httpauth: sent domains to daemon: %s", t);

        if(read_response(ctx, r, &code, NULL, NULL) == -1)
            goto finally;

        if(code != 202)
        {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "httpauth: protocol error (Expected 202, got %d)", code);
            goto finally;
        }
    }

    /* We're cool! */
    ret = 0;
    ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, "httpauth: connected to daemon");

finally:
    if(ret == -1)
        disconnect_socket(ctx, r->server);

    return ret;
}

/* Make sure our connection identifier is unique */
static apr_status_t connection_gone (void *data)
{
    conn_current = NULL;
    conn_seen++;
    return APR_SUCCESS;
}

int write_request(httpauth_context_t* ctx, request_rec* r)
{
    char pidid[40];
    char connid[40];
    int i, c = 0;
    const char* t;
    const apr_array_header_t* hdrs_arr;
    const apr_table_entry_t* elts;

    /* When the connection goes away, call our handler */
    if(conn_current != r->connection)
    {
        conn_current = r->connection;
        apr_pool_cleanup_register(r->connection->pool, r,
                            connection_gone, apr_pool_cleanup_null);
    }

    /* A unique per connection id */
    snprintf(connid, sizeof(connid), "0x%X-%X-%X",
             (unsigned int)r->connection, conn_seen, (unsigned int)r->connection->id);
    connid[sizeof(connid) - 1] = 0;
    snprintf(pidid, sizeof(pidid), "%d", (unsigned int)getpid());
    pidid[sizeof(pidid) - 1] = 0;
    t = apr_pstrcat(r->pool, pidid, ":", connid, NULL);

    /* Send the request header to httpauthd */
    t = apr_pstrcat(r->pool, "AUTH ", t, " ", r->method,
                    " ", r->unparsed_uri, "\n", NULL);

    if(write_data(ctx, r->server, t) == -1)
        return -1;

    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
        "httpauth: sent auth request to daemon: %s", t);

    /* Now send the headers to httpauthd */

    hdrs_arr = apr_table_elts(r->headers_in);
    elts = (const apr_table_entry_t*)hdrs_arr->elts;

    for(i = 0; i < hdrs_arr->nelts; i++)
    {
        if(!elts[i].val)
            continue;

        /* Filter out headers we don't want */
        if(strcasecmp(elts[i].key, r->proxyreq == PROXYREQ_PROXY ?
                      "Proxy-Authorization" : "Authorization") == 0)
        {
            t = trim_start(elts[i].val);

            if(strncasecmp(t, AUTH_PREFIX_BASIC, strlen(AUTH_PREFIX_BASIC)) == 0 &&
               !(ctx->types & AUTH_TYPE_BASIC))
                continue;

            else if(strncasecmp(t, AUTH_PREFIX_DIGEST, strlen(AUTH_PREFIX_DIGEST)) == 0 &&
                    !(ctx->types & AUTH_TYPE_DIGEST))
                continue;

            else if(strncasecmp(t, AUTH_PREFIX_NTLM, strlen(AUTH_PREFIX_NTLM)) == 0 &&
                    !(ctx->types & AUTH_TYPE_NTLM))
                continue;

            /* Only allow unknown if we don't have it */
            else if(!(ctx->types & AUTH_TYPE_ANY))
                continue;

            /* Extra blank line when at end */
            t = apr_pstrcat(r->pool, "Authorization: ", elts[i].val, "\n", NULL);

            if(write_data(ctx, r->server, t) == -1)
                return HTTP_INTERNAL_SERVER_ERROR;

            c++;
        }
    }

    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                  "httpauth: sent %d headers to daemon", c);

    return write_data(ctx, r->server, "\n");
}

static int httpauth_authenticate(request_rec* r)
{
    httpauth_context_t* ctx;
    const char* authtype;
    int code = 0;
    int ccode = 0;
    char* details = NULL;
    request_rec* mainreq;
    int retried = 0;

    /* Make sure it's for us */
    if(!(authtype = ap_auth_type(r)) || strcasecmp(HTTPAUTH_AUTHTYPE, authtype) != 0)
        return DECLINED;

    ctx = (httpauth_context_t*)ap_get_module_config(r->per_dir_config,
                                                  &httpauth_module);

    if(!ctx->socketname || !ctx->handler)
        return DECLINED;

    mainreq = r;

    while(mainreq->main != NULL)
        mainreq = mainreq->main;

    while(mainreq->prev != NULL)
        mainreq = mainreq->prev;

    /* Check if we've already authenticated this request */
    if(ap_get_module_config(mainreq->request_config, &httpauth_module))
        return OK;

/* For jumping to when a connection has been closed */
retry:

    if(ctx->socket == -1)
    {
        if(connect_httpauth(ctx, r) == -1)
            return HTTP_INTERNAL_SERVER_ERROR;
    }

    /* Make sure we're starting on a clean slate */
    read_junk(ctx, r);

    /* Send off a request */
    if(write_request(ctx, r) == -1 ||
	   read_response(ctx, r, &code, &ccode, &details) == -1)
    {
        /*
         * If our connection was closed by httpauthd then this
         * is where we get the error. Just do one retry to
         * try and reconnect. This happens often when restarting
         * httpauthd.
         */

        if(ctx->socket == -1 && !retried)
        {
        	ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r,
                		  "httpauth: reconnecting to to httpauthd");
            retried = 1;
            goto retry;
        }

		ap_log_rerror(APLOG_MARK, APLOG_ERR, APR_FROM_OS_ERROR(errno), r,
					  "httpauth: couldn't send request to httpauthd");

        return HTTP_INTERNAL_SERVER_ERROR;
    }

    if(code != 200)
    {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                "httpauth: protocol error: unexpected code: %d", code);
        return HTTP_INTERNAL_SERVER_ERROR;
    }

    /* Copy over other headers */
    if(read_copy_headers(ctx, ccode, r) == -1)
        return HTTP_INTERNAL_SERVER_ERROR;

    if(ccode == 200)
    {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "httpauth: successful authentication for user: %s", details);

        r->user = apr_pstrdup(r->pool, details);
        r->ap_auth_type = HTTPAUTH_AUTHTYPE;

        /* Mark request as successfully authenticated */
        ap_set_module_config(r->request_config, &httpauth_module, details);
        return OK;
    }

    return ccode;
}

static int httpauth_access(request_rec *r)
{
    /* TODO: We need to support require directives */
    return OK;
}

static void register_hooks(apr_pool_t *p)
{
    /* static const char* cfg_post[] = { "http_core.c", NULL }; */

    ap_hook_check_user_id(httpauth_authenticate, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_auth_checker(httpauth_access, NULL, NULL, APR_HOOK_MIDDLE);
}

module AP_MODULE_DECLARE_DATA httpauth_module =
{
    STANDARD20_MODULE_STUFF,
    httpauth_dir_config,        /* dir config creater */
    NULL,                       /* dir merger --- default is to override */
    NULL,                       /* server config */
    NULL,                       /* merge server config */
    httpauth_cmds,              /* command table */
    register_hooks              /* register hooks */
};

/*
 * Apache modules seem to want to be all in one
 * object file, at least when statically compiled.
 * so we include this here
 */
#include "../common/sock_any.c"
#include "../common/stringx.c"