/* 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
{
  const char* filename;       /* The file name with the user names */
  const char* realm;          /* The realm for basic authentication */
  const char* domains;      /* Domains for which digest auth is valid */
  int cache_max;            /* Maximum number of connections at once */

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

/* The defaults for the context */
static const simple_context_t simple_defaults =
{
  NULL,               /* filename */
  NULL,               /* realm */
  NULL,               /* domains */
  1000,               /* cache_max */
  NULL                /* cache */
};


/* -------------------------------------------------------------------------------
 * 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;

  if(ctx->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;

  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;

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

  ha_lock(NULL);

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

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

  ha_unlock(NULL);

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

  return HA_OK;
}

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

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

  ha_lock(NULL);

    while(hash_count(ctx->cache) >= ctx->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_ERROR;
  }

  return HA_OK;
}

static int complete_digest_ha1(simple_context_t* ctx, digest_record_t* rec,
                               ha_buffer_t* buf, const char* user, int* code)
{
  FILE* f;
  int found = 0;
  char* t;
  char line[SIMPLE_MAXLINE];

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

  /*
   * 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, "error reading basic password file");
      *code = HA_SERVER_ERROR;
      break;
    }

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

      /* Check the user */
      if(strcmp(line, user) == 0)
      {
        /* Now decode the rest of the line and see if it matches up */
        t = ha_bufdechex(buf, t, MD5_LEN);

        if(t != NULL)
        {
          memcpy(rec->ha1, t, MD5_LEN);
          found = 1;
          break;
        }

        else
        {
          if(ha_buferr(buf))
            break;

          ha_messagex(LOG_WARNING, "user '%s' found in file, but password not in digest format", user);
        }
      }
    }

    fclose(f);
  }

  if(ha_buferr(buf))
    return HA_ERROR;

  return found ? HA_FALSE : HA_OK;
}

static int validate_user_password(simple_context_t* ctx, ha_buffer_t* buf,
                                  const char* user, const char* clearpw, int* code)
{
  FILE* f;
  int found = 0;
  char line[SIMPLE_MAXLINE];
  unsigned char ha1[MD5_LEN];
  char* t;
  char* t2;

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

  digest_makeha1(ha1, user, ctx->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, "error reading basic password file");
      *code = HA_SERVER_ERROR;
      break;
    }

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

      /* Check the user */
      if(strcmp(line, user) == 0)
      {
        /* We can validate against an ha1, so check if it decodes as one */
        t2 = ha_bufdechex(buf, t, MD5_LEN);

        if(t2 && memcmp(ha1, t2, MD5_LEN) == 0)
        {
          memcpy(ha1, t2, MD5_LEN);
          found = 1;
          break;
        }

        /* Otherwise we try a nice crypt style password */
        else
        {
          /* Not sure if crypt is thread safe so we lock */
          ha_lock();

            /* Check the password */
            if(strcmp(crypt(clearpw, t), t) == 0)
              found = 1;

          ha_unlock();

          if(found)
            break;
        }

        if(ha_buferr(buf))
          break;
      }
    }

    fclose(f);
  }

  if(ha_buferr(buf))
    return HA_ERROR;

  return found ? HA_FALSE : HA_OK;
}

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(basic_parse(header, buf, &basic) == HA_ERROR)
    return HA_ERROR;

  /* 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))
  {
    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, &(resp->code));

finally:

  if(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)
{
  unsigned char nonce[DIGEST_NONCE_LEN];
  const char* header;

  /* Generate an nonce */
  digest_makenonce(nonce, g_simple_secret, NULL);

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

  if(!header)
    return HA_ERROR;

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

  return HA_OK;
}

static int simple_digest_response(simple_context_t* ctx, const char* header,
                           const char* method, const char* uri, int timeout,
                           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;

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

  if(digest_parse(header, buf, &dg, nonce) == HA_ERROR)
    return HA_ERROR;

  r = digest_checknonce(nonce, g_simple_secret, &expiry);
  if(r != HA_OK)
  {
    if(r == HA_FALSE)
      ha_messagex(LOG_WARNING, "digest response contains invalid nonce");

    ret = r;
    goto finally;
  }

  rec = get_cached_digest(ctx, nonce);

  /* Check to see if we're stale */
  if((expiry + timeout) <= time(NULL))
  {
    stale = 1;
    goto finally;
  }

  if(!rec)
  {
    /*
     * 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_ERROR;
      goto finally;
    }

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

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

  ret = digest_check(ctx->realm, method, uri, buf, &dg, rec);

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

    /* Figure out if we need a new nonce */
    if((expiry + (timeout - (timeout / 8))) < time(NULL))
    {
      digest_makenonce(nonce, g_simple_secret, NULL);
      stale = 1;
    }

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

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

    /* Put the connection into the cache */
    if(save_cached_digest(ctx, rec) == HA_ERROR)
      ret = HA_ERROR;
    else
      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);

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

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

  else if(strcmp(name, "digestdomains") == 0)
  {
    ctx->domains = value;
    return HA_OK;
  }

  else if(strcmp(name, "cachemax") == 0)
  {
    return ha_confint(name, value, 0, 0x7FFFFFFF, &(ctx->cache_max));
  }

  return HA_FALSE;
}

int simple_init(ha_context_t* context)
{
  /* Global initialization */
  if(!context)
  {
    return ha_genrandom(g_simple_secret, DIGEST_SECRET_LEN);
  }

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

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


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

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

    close(fd);

    /* 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_ERROR;
    }
  }

  return HA_OK;
}

void simple_destroy(ha_context_t* context)
{
  /* Per context destroy */
  if(context)
  {
    simple_context_t* ctx = (simple_context_t*)(context->data);

    /* Note: We don't need to be thread safe here anymore */
    hash_free(ctx->cache);
  }
}

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;
  int ret = HA_FALSE;
  int found = 0;
  basic_header_t basic;


  ha_lock(NULL);

    /* Purge the cache */
    hash_purge(ctx->cache, time(NULL) - context->timeout);

  ha_unlock(NULL);


  /* 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->types & HA_TYPE_DIGEST)
  {
    header = ha_getheader(req, "Authorization", HA_PREFIX_DIGEST);
    if(header)
    {
      ret = simple_digest_response(ctx, header, req->args[AUTH_ARG_METHOD],
                            req->args[AUTH_ARG_URI], context->timeout,
                            resp, buf);
      if(ret == HA_ERROR)
        return ret;
    }
  }

  /* Or a basic authentication */
  if(!header && context->types & HA_TYPE_BASIC)
  {
    header = ha_getheader(req, "Authorization", HA_PREFIX_BASIC);
    if(header)
    {
      ret = simple_basic_response(ctx, header, resp, buf);
      if(ret == HA_ERROR)
        return ret;
    }
  }


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

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

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

      if(ha_buferr(buf))
        return HA_ERROR;

      ha_addheader(resp, "WWW-Authenticate", ha_bufdata(buf));
    }
  }

  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 */
  &simple_defaults,        /* A default context */
  sizeof(simple_context_t) /* Size of the context */
};