/* On some linux this is required to get crypt to show itself */
#define _XOPEN_SOURCE

#include "usuals.h"
#include "httpauthd.h"
#include "defaults.h"
#include "basic.h"
#include "digest.h"
#include "hash.h"
#include "md5.h"

#include <syslog.h>
#include <fcntl.h>
#include <unistd.h>

unsigned char g_simple_secret[DIGEST_SECRET_LEN];

#define SIMPLE_MAXLINE 256
#define BASIC_ESTABLISHED  (void*)1

/* -------------------------------------------------------------------------------
 * Structures
 */

typedef struct simple_context
{
  /* Settings ----------------------------------------------------------- */
  const char* filename;     /* The file name with the user names */
  ha_options_t* opts;       /* Options from httpauthd.c */

  /* Context ----------------------------------------------------------- */
  hash_t* cache;            /* Some cached records or basic */
}
simple_context_t;


/* -------------------------------------------------------------------------------
 * Internal Functions
 */

static void free_hash_object(void* arg, void* val)
{
  if(val && val != BASIC_ESTABLISHED)
    free(val);
}

static digest_record_t* get_cached_digest(simple_context_t* ctx, unsigned char* nonce)
{
  digest_record_t* rec;

  ASSERT(ctx && nonce);

  if(ctx->opts->cache_max == 0)
    return NULL;

  ha_lock(NULL);

    rec = (digest_record_t*)hash_get(ctx->cache, nonce);

    /* Just in case it's a basic :) */
    if(rec && rec != BASIC_ESTABLISHED)
      hash_rem(ctx->cache, nonce);

  ha_unlock(NULL);

  ASSERT(!rec || memcmp(nonce, rec->nonce, DIGEST_NONCE_LEN) == 0);
  return rec;
}

static int have_cached_basic(simple_context_t* ctx, unsigned char* key)
{
  int ret = 0;

  ASSERT(ctx && key);

  ha_lock(NULL);

    ret = (hash_get(ctx->cache, key) == BASIC_ESTABLISHED);

  ha_unlock(NULL);

  return ret;
}

static int save_cached_digest(simple_context_t* ctx, digest_record_t* rec)
{
  int r;

  ASSERT(ctx && rec);

  if(ctx->opts->cache_max == 0)
  {
    free_hash_object(NULL, rec);
    return HA_FALSE;
  }

  ha_lock(NULL);

    while(hash_count(ctx->cache) >= ctx->opts->cache_max)
      hash_bump(ctx->cache);

    r = hash_set(ctx->cache, rec->nonce, rec);

  ha_unlock(NULL);

  if(!r)
  {
    free_hash_object(NULL, rec);
    ha_messagex(LOG_CRIT, "out of memory");
    return HA_CRITERROR;
  }

  return HA_OK;
}

static int add_cached_basic(simple_context_t* ctx, unsigned char* key)
{
  int r;

  ASSERT(ctx && key);

  if(ctx->opts->cache_max == 0)
    return HA_FALSE;

  ha_lock(NULL);

    while(hash_count(ctx->cache) >= ctx->opts->cache_max)
      hash_bump(ctx->cache);

    r = hash_set(ctx->cache, key, BASIC_ESTABLISHED);

  ha_unlock(NULL);

  if(!r)
  {
    ha_messagex(LOG_CRIT, "out of memory");
    return HA_CRITERROR;
  }

  return HA_OK;
}

static int complete_digest_ha1(simple_context_t* ctx, digest_record_t* rec,
                               ha_buffer_t* buf, const char* user)
{
  FILE* f;
  char* t;
  char* t2;
  size_t len;
  char line[SIMPLE_MAXLINE];
  int ret = HA_FALSE;

  ASSERT(ctx && rec && buf && user && user[0]);
  ha_messagex(LOG_DEBUG, "searching password file for user's ha1: %s", user);

  f = fopen(ctx->filename, "r");
  if(!f)
  {
    ha_message(LOG_ERR, "simple: can't open file for basic auth: %s", ctx->filename);
    return HA_FAILED;
  }

  /*
   * Note: There should be no returns or jumps between
   * this point and the closing of the file below.
   */

  /* Now look through the whole file */
  while(!feof(f))
  {
    fgets(line, SIMPLE_MAXLINE, f);

    if(ferror(f))
    {
      ha_message(LOG_ERR, "simple: error reading basic password file");
      ret = HA_FAILED;
      break;
    }

    t = strchr(line, ':');
    if(t)
    {
      /* Split the line */
      *t = 0;
      t++;

      /* Check the user */
      if(strcmp(line, user) == 0)
      {
        /* Otherwise it might be a digest type ha1. */
        t2 = strchr(t, ':');
        if(t2)
        {
          *t2 = 0;
          t2++;

          /* Check the realm */
          if(strcmp(t, ctx->opts->realm) == 0)
          {
            len = MD5_LEN;

            /* Now try antd decode the ha1  */
            t = ha_bufdechex(buf, t2, &len);
            if(t && len == MD5_LEN)
            {
              ha_messagex(LOG_DEBUG, "simple: found ha1 for user: %s", user);
              memcpy(rec->ha1, t, MD5_LEN);
              ret = HA_OK;
              break;
            }
          }
        }

        if(!t2 || ret != HA_OK)
          ha_messagex(LOG_WARNING, "simple: user '%s' found in file, but password not in digest format", user);
      }
    }
  }

  fclose(f);

  if(ha_buferr(buf))
    return HA_CRITERROR;

  return ret;
}

static int validate_user_password(simple_context_t* ctx, ha_buffer_t* buf,
                                  const char* user, const char* clearpw)
{
  FILE* f;
  char line[SIMPLE_MAXLINE];
  unsigned char ha1[MD5_LEN];
  char* t;
  char* t2;
  size_t len;
  int ret = HA_FALSE;

  ASSERT(ctx && buf);
  ASSERT(user && user[0] && clearpw);
  ha_messagex(LOG_DEBUG, "simple: validating user against password file: %s", user);

  f = fopen(ctx->filename, "r");
  if(!f)
  {
    ha_message(LOG_ERR, "simple: can't open file for basic auth: %s", ctx->filename);
    return HA_FAILED;
  }

  digest_makeha1(ha1, user, ctx->opts->realm, clearpw);

  /*
   * Note: There should be no returns or jumps between
   * this point and the closing of the file below.
   */

  /* Now look through the whole file */
  while(!feof(f))
  {
    fgets(line, SIMPLE_MAXLINE, f);

    if(ferror(f))
    {
      ha_message(LOG_ERR, "simple: error reading basic password file");
      ret = HA_FAILED;
      break;
    }

    /* Take white space off end of line */
    t = line + strlen(line);
    while(t != line && isspace(*(t - 1)))
    {
      *(t - 1) = 0;
      t--;
    }

    t = strchr(line, ':');
    if(t)
    {
      /* Split the line */
      *t = 0;
      t++;

      /* Check the user */
      if(strcmp(line, user) == 0)
      {
        /* Not sure if crypt is thread safe so we lock */
        ha_lock(NULL);

          /* Check the password */
          t2 = crypt(clearpw, t);

        ha_unlock(NULL);

        if(strcmp(crypt(clearpw, t), t) == 0)
        {
          ha_messagex(LOG_DEBUG, "simple: found valid crypt password for user: %s", user);
          ret = HA_OK;
          break;
        }

        /* Otherwise it might be a digest type ha1. */
        t2 = strchr(t, ':');
        if(t2)
        {
          *t2 = 0;
          t2++;

          /* Check the realm */
          if(strcmp(t, ctx->opts->realm) == 0)
          {
            len = MD5_LEN;

            /* Now try antd decode the ha1  */
            t = ha_bufdechex(buf, t2, &len);
            if(t && len == MD5_LEN && memcmp(ha1, t, MD5_LEN) == 0)
            {
              ha_messagex(LOG_DEBUG, "simple: found valid ha1 for user: %s", user);
              ret = HA_OK;
              break;
            }
          }
        }

        if(ha_buferr(buf))
          break;
      }
    }
  }

  fclose(f);

  if(ha_buferr(buf))
    return HA_CRITERROR;

  return ret;
}

static int simple_basic_response(simple_context_t* ctx, const char* header,
                          ha_response_t* resp, ha_buffer_t* buf)
{
  basic_header_t basic;
  int ret = HA_FALSE;
  int found = 0;
  int r;

  ASSERT(buf && header && resp && buf);

  if((r = basic_parse(header, buf, &basic)) < 0)
    return r;

  /* Past this point we don't return directly */

  /* Check and see if this connection is in the cache */
  if(have_cached_basic(ctx, basic.key))
  {
    ha_messagex(LOG_NOTICE, "simple: validated basic user against cache: %s", basic.user);
    found = 1;
    ret = HA_OK;
    goto finally;
  }

  /* If we have a user name and password */
  if(!basic.user || !basic.user[0] ||
     !basic.password || !basic.password[0])
    goto finally;


  ret = validate_user_password(ctx, buf, basic.user, basic.password);

  if(ret == HA_OK)
    ha_messagex(LOG_NOTICE, "simple: validated basic user against file: %s", basic.user);

  else
    ha_messagex(LOG_WARNING, "simple: basic authentication failed for user: %s", basic.user);

finally:

  if(ret == HA_OK)
  {
    resp->code = HA_SERVER_ACCEPT;
    resp->detail = basic.user;

    /* We put this connection into the successful connections */
    ret = add_cached_basic(ctx, basic.key);
  }

  return ret;
}

static int simple_digest_challenge(simple_context_t* ctx, ha_response_t* resp,
                                  ha_buffer_t* buf, int stale)
{
  const char* nonce_str;
  const char* header;

  ASSERT(ctx && resp && buf);

  /* Generate an nonce */

#ifdef _DEBUG
  if(ctx->opts->digest_debugnonce)
  {
    nonce_str = ctx->opts->digest_debugnonce;
    ha_messagex(LOG_WARNING, "simple: using debug nonce. security non-existant.");
  }
  else
#endif
  {
    unsigned char nonce[DIGEST_NONCE_LEN];
    digest_makenonce(nonce, g_simple_secret, NULL);

    nonce_str = ha_bufenchex(buf, nonce, DIGEST_NONCE_LEN);
    if(!nonce_str)
      return HA_CRITERROR;
  }


  /* Now generate a message to send */
  header = digest_challenge(buf, nonce_str, ctx->opts->realm,
                            ctx->opts->digest_domains, stale);

  if(!header)
    return HA_CRITERROR;

  /* And append it nicely */
  resp->code = HA_SERVER_DECLINE;
  ha_addheader(resp, "WWW-Authenticate", header);

  ha_messagex(LOG_DEBUG, "simple: created digest challenge with nonce: %s", nonce_str);
  return HA_OK;
}

static int simple_digest_response(simple_context_t* ctx, const char* header,
                           const char* method, const char* uri,
                           ha_response_t* resp, ha_buffer_t* buf)
{
  unsigned char nonce[DIGEST_NONCE_LEN];
  digest_header_t dg;
  digest_record_t* rec = NULL;
  const char* t;
  time_t expiry;
  int ret = HA_FALSE;
  int stale = 0;
  int r;

  ASSERT(ctx && header && method && uri && resp && buf);

  /* We use this below to send a default response */
  resp->code = -1;

  if((r = digest_parse(header, buf, &dg, nonce)) < 0)
    return r;

#ifdef _DEBUG
  if(ctx->opts->digest_debugnonce)
  {
    if(dg.nonce && strcmp(dg.nonce, ctx->opts->digest_debugnonce) != 0)
    {
      resp->code = HA_SERVER_BADREQ;
      ret = HA_FALSE;
      ha_messagex(LOG_WARNING, "simple: digest response contains invalid nonce");
      goto finally;
    }

    /* Do a rough hash into the real nonce, for use as a key */
    md5_string(nonce, ctx->opts->digest_debugnonce);

    /* Debug nonce's never expire */
    expiry = time(NULL);
  }
  else
#endif
  {
    r = digest_checknonce(nonce, g_simple_secret, &expiry);
    if(r != HA_OK)
    {
      if(r == HA_FALSE)
      {
        resp->code = HA_SERVER_BADREQ;
        ha_messagex(LOG_WARNING, "simple: digest response contains invalid nonce");
      }

      ret = r;
      goto finally;
    }
  }

  rec = get_cached_digest(ctx, nonce);

  /* Check to see if we're stale */
  if((expiry + ctx->opts->cache_timeout) <= time(NULL))
  {
    ha_messagex(LOG_INFO, "simple: nonce expired, sending stale challenge: %s",
                dg.username);

    stale = 1;
    goto finally;
  }

  if(!rec)
  {
    ha_messagex(LOG_INFO, "simple: no record in cache, creating one: %s", dg.username);

    /*
     * If we're valid but don't have a record in the
     * cache then complete the record properly.
     */

    rec = digest_makerec(nonce, dg.username);
    if(!rec)
    {
      ret = HA_CRITERROR;
      goto finally;
    }

    r = complete_digest_ha1(ctx, rec, buf, dg.username);
    if(r != HA_OK)
    {
      ret = r;
      goto finally;
    }
  }

  /* Increment our nonce count */
  rec->nc++;

  ret = digest_check(ctx->opts->realm, method,
                     ctx->opts->digest_ignoreuri ? NULL : uri, buf, &dg, rec);

  if(ret == HA_BADREQ)
  {
    ret = HA_FALSE;
    resp->code = HA_SERVER_BADREQ;
  }

  else if(ret == HA_OK)
  {
    resp->code = HA_SERVER_ACCEPT;
    resp->detail = dg.username;

    /* Figure out if we need a new nonce */
    if((expiry + (ctx->opts->cache_timeout -
                  (ctx->opts->cache_timeout / 8))) < time(NULL))
    {
      ha_messagex(LOG_INFO, "simple: nonce almost expired, creating new one: %s",
                  dg.username);

      digest_makenonce(nonce, g_simple_secret, NULL);
      stale = 1;
    }

    t = digest_respond(buf, &dg, rec, stale ? nonce : NULL);
    if(!t)
    {
      ret = HA_CRITERROR;
      goto finally;
    }

    if(t[0])
      ha_addheader(resp, "Authentication-Info", t);

    ha_messagex(LOG_NOTICE, "simple: validated digest user: %s", dg.username);

    /* Put the connection into the cache */
    if((r = save_cached_digest(ctx, rec)) < 0)
      ret = r;

    rec = NULL;
  }

finally:

  /* If the record wasn't stored away then free it */
  if(rec)
    free(rec);

  /* If nobody above responded then challenge the client again */
  if(resp->code == -1)
    return simple_digest_challenge(ctx, resp, buf, stale);

  return ret;
}


/* -------------------------------------------------------------------------------
 * Handler Functions
 */

int simple_config(ha_context_t* context, const char* name, const char* value)
{
  simple_context_t* ctx = (simple_context_t*)(context->data);

  ASSERT(name && name[0] && value && value[0]);

  if(strcmp(name, "passwordfile") == 0)
  {
    ctx->filename = value;
    return HA_OK;
  }

  return HA_FALSE;
}

int simple_init(ha_context_t* context)
{
  /* Global initialization */
  if(!context)
  {
    ha_messagex(LOG_DEBUG, "simple: generating secret");
    return ha_genrandom(g_simple_secret, DIGEST_SECRET_LEN);
  }

  /* Context specific initialization */
  else
  {
    simple_context_t* ctx = (simple_context_t*)(context->data);
    int fd;

    ASSERT(ctx);

    /* Make sure there are some types of authentication we can do */
    if(!(context->opts.types & (HA_TYPE_BASIC | HA_TYPE_DIGEST)))
    {
      ha_messagex(LOG_ERR, "simple: module configured, but does not implement any "
                           "configured authentication type.");
      return HA_FAILED;
    }


    /* Check to make sure the file exists */
    if(!ctx->filename)
    {
      ha_messagex(LOG_ERR, "simple: configuration incomplete. "
                           "Must have a PasswordFile configured.");
      return HA_FAILED;
    }

    fd = open(ctx->filename, O_RDONLY);
    if(fd == -1)
    {
      ha_message(LOG_ERR, "simple: can't open file for authentication: %s", ctx->filename);
      return HA_FAILED;
    }

    close(fd);

    ASSERT(!ctx->cache);

    /* The cache for digest records and basic */
    if(!(ctx->cache = hash_create(MD5_LEN, free_hash_object, NULL)))
    {
      ha_messagex(LOG_CRIT, "out of memory");
      return HA_CRITERROR;
    }

    /* Copy some settings over for easy access */
    ctx->opts = &(context->opts);

    ha_messagex(LOG_INFO, "simple: initialized handler");
  }

  return HA_OK;
}

void simple_destroy(ha_context_t* context)
{
  /* Per context destroy */
  if(context)
  {
    /* Note: We don't need to be thread safe here anymore */
    simple_context_t* ctx = (simple_context_t*)(context->data);

    if(ctx->cache)
      hash_free(ctx->cache);

    ha_messagex(LOG_INFO, "simple: uninitialized handler");
  }
}

int simple_process(ha_context_t* context, ha_request_t* req,
                 ha_response_t* resp, ha_buffer_t* buf)
{
  simple_context_t* ctx = (simple_context_t*)(context->data);
  const char* header = NULL;
  int ret = HA_FALSE;
  int found = 0;
  basic_header_t basic;
  int r;

  ASSERT(context && req && resp && buf);
  ASSERT(req->args[AUTH_ARG_METHOD]);
  ASSERT(req->args[AUTH_ARG_URI]);

  ha_lock(NULL);

    /* Purge the cache */
    r = hash_purge(ctx->cache, time(NULL) - ctx->opts->cache_timeout);

  ha_unlock(NULL);

  if(r > 0)
    ha_messagex(LOG_DEBUG, "simple: purged cache records: %d", r);

  /* We use this below to detect whether to send a default response */
  resp->code = -1;


  /* Check the headers and see if we got a response thingy */
  if(context->opts.types & HA_TYPE_DIGEST)
  {
    header = ha_getheader(req, "Authorization", HA_PREFIX_DIGEST);
    if(header)
    {
      ha_messagex(LOG_DEBUG, "simple: processing digest auth header");
      ret = simple_digest_response(ctx, header, req->args[AUTH_ARG_METHOD],
                            req->args[AUTH_ARG_URI], resp, buf);
      if(ret < 0)
        return ret;
    }
  }

  /* Or a basic authentication */
  if(!header && context->opts.types & HA_TYPE_BASIC)
  {
    ha_messagex(LOG_DEBUG, "simple: processing basic auth header");
    header = ha_getheader(req, "Authorization", HA_PREFIX_BASIC);
    if(header)
    {
      ret = simple_basic_response(ctx, header, resp, buf);
      if(ret < 0)
        return ret;
    }
  }


  /* Send a default response if that's what we need */
  if(resp->code == -1)
  {
    resp->code = HA_SERVER_DECLINE;

    if(context->opts.types & HA_TYPE_BASIC)
    {
      ha_bufmcat(buf, "BASIC realm=\"", ctx->opts->realm , "\"", NULL);

      if(ha_buferr(buf))
        return HA_CRITERROR;

      ha_addheader(resp, "WWW-Authenticate", ha_bufdata(buf));
      ha_messagex(LOG_DEBUG, "simple: sent basic auth request");
    }

    if(context->opts.types & HA_TYPE_DIGEST)
    {
      ret = simple_digest_challenge(ctx, resp, buf, 0);
      if(ret < 0)
        return ret;
    }
  }

  return ret;
}


/* -------------------------------------------------------------------------------
 * Handler Definition
 */

ha_handler_t simple_handler =
{
  "SIMPLE",                /* The type */
  simple_init,             /* Initialization function */
  simple_destroy,          /* Uninitialization routine */
  simple_config,           /* Config routine */
  simple_process,          /* Processing routine */
  NULL,                    /* A default context */
  sizeof(simple_context_t) /* Size of the context */
};