curl/lib/http_digest.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_CRYPTO_AUTH)

#include "urldata.h"
#include "sendf.h"
#include "rawstr.h"
#include "curl_base64.h"
#include "curl_md5.h"
#include "http_digest.h"
#include "strtok.h"
#include "url.h" /* for Curl_safefree() */
#include "curl_memory.h"
#include "non-ascii.h" /* included for Curl_convert_... prototypes */
#include "warnless.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

/* The last #include file should be: */
#include "memdebug.h"

#define MAX_VALUE_LENGTH 256
#define MAX_CONTENT_LENGTH 1024

static void digest_cleanup_one(struct digestdata *dig);

/*
 * Return 0 on success and then the buffers are filled in fine.
 *
 * Non-zero means failure to parse.
 */
static int get_pair(const char *str, char *value, char *content,
                    const char **endptr)
{
  int c;
  bool starts_with_quote = FALSE;
  bool escape = FALSE;

  for(c=MAX_VALUE_LENGTH-1; (*str && (*str != '=') && c--); )
    *value++ = *str++;
  *value=0;

  if('=' != *str++)
    /* eek, no match */
    return 1;

  if('\"' == *str) {
    /* this starts with a quote so it must end with one as well! */
    str++;
    starts_with_quote = TRUE;
  }

  for(c=MAX_CONTENT_LENGTH-1; *str && c--; str++) {
    switch(*str) {
    case '\\':
      if(!escape) {
        /* possibly the start of an escaped quote */
        escape = TRUE;
        *content++ = '\\'; /* even though this is an escape character, we still
                              store it as-is in the target buffer */
        continue;
      }
      break;
    case ',':
      if(!starts_with_quote) {
        /* this signals the end of the content if we didn't get a starting
           quote and then we do "sloppy" parsing */
        c=0; /* the end */
        continue;
      }
      break;
    case '\r':
    case '\n':
      /* end of string */
      c=0;
      continue;
    case '\"':
      if(!escape && starts_with_quote) {
        /* end of string */
        c=0;
        continue;
      }
      break;
    }
    escape = FALSE;
    *content++ = *str;
  }
  *content=0;

  *endptr = str;

  return 0; /* all is fine! */
}

/* Test example headers:

WWW-Authenticate: Digest realm="testrealm", nonce="1053604598"
Proxy-Authenticate: Digest realm="testrealm", nonce="1053604598"

*/

CURLdigest Curl_input_digest(struct connectdata *conn,
                             bool proxy,
                             const char *header) /* rest of the *-authenticate:
                                                    header */
{
  char *token = NULL;
  char *tmp = NULL;
  bool foundAuth = FALSE;
  bool foundAuthInt = FALSE;
  struct SessionHandle *data=conn->data;
  bool before = FALSE; /* got a nonce before */
  struct digestdata *d;

  if(proxy) {
    d = &data->state.proxydigest;
  }
  else {
    d = &data->state.digest;
  }

  /* skip initial whitespaces */
  while(*header && ISSPACE(*header))
    header++;

  if(checkprefix("Digest", header)) {
    header += strlen("Digest");

    /* If we already have received a nonce, keep that in mind */
    if(d->nonce)
      before = TRUE;

    /* clear off any former leftovers and init to defaults */
    digest_cleanup_one(d);

    for(;;) {
      char value[MAX_VALUE_LENGTH];
      char content[MAX_CONTENT_LENGTH];

      while(*header && ISSPACE(*header))
        header++;

      /* extract a value=content pair */
      if(!get_pair(header, value, content, &header)) {
        if(Curl_raw_equal(value, "nonce")) {
          d->nonce = strdup(content);
          if(!d->nonce)
            return CURLDIGEST_NOMEM;
        }
        else if(Curl_raw_equal(value, "stale")) {
          if(Curl_raw_equal(content, "true")) {
            d->stale = TRUE;
            d->nc = 1; /* we make a new nonce now */
          }
        }
        else if(Curl_raw_equal(value, "realm")) {
          d->realm = strdup(content);
          if(!d->realm)
            return CURLDIGEST_NOMEM;
        }
        else if(Curl_raw_equal(value, "opaque")) {
          d->opaque = strdup(content);
          if(!d->opaque)
            return CURLDIGEST_NOMEM;
        }
        else if(Curl_raw_equal(value, "qop")) {
          char *tok_buf;
          /* tokenize the list and choose auth if possible, use a temporary
             clone of the buffer since strtok_r() ruins it */
          tmp = strdup(content);
          if(!tmp)
            return CURLDIGEST_NOMEM;
          token = strtok_r(tmp, ",", &tok_buf);
          while(token != NULL) {
            if(Curl_raw_equal(token, "auth")) {
              foundAuth = TRUE;
            }
            else if(Curl_raw_equal(token, "auth-int")) {
              foundAuthInt = TRUE;
            }
            token = strtok_r(NULL, ",", &tok_buf);
          }
          free(tmp);
          /*select only auth o auth-int. Otherwise, ignore*/
          if(foundAuth) {
            d->qop = strdup("auth");
            if(!d->qop)
              return CURLDIGEST_NOMEM;
          }
          else if(foundAuthInt) {
            d->qop = strdup("auth-int");
            if(!d->qop)
              return CURLDIGEST_NOMEM;
          }
        }
        else if(Curl_raw_equal(value, "algorithm")) {
          d->algorithm = strdup(content);
          if(!d->algorithm)
            return CURLDIGEST_NOMEM;
          if(Curl_raw_equal(content, "MD5-sess"))
            d->algo = CURLDIGESTALGO_MD5SESS;
          else if(Curl_raw_equal(content, "MD5"))
            d->algo = CURLDIGESTALGO_MD5;
          else
            return CURLDIGEST_BADALGO;
        }
        else {
          /* unknown specifier, ignore it! */
        }
      }
      else
        break; /* we're done here */

      /* pass all additional spaces here */
      while(*header && ISSPACE(*header))
        header++;
      if(',' == *header)
        /* allow the list to be comma-separated */
        header++;
    }
    /* We had a nonce since before, and we got another one now without
       'stale=true'. This means we provided bad credentials in the previous
       request */
    if(before && !d->stale)
      return CURLDIGEST_BAD;

    /* We got this header without a nonce, that's a bad Digest line! */
    if(!d->nonce)
      return CURLDIGEST_BAD;
  }
  else
    /* else not a digest, get out */
    return CURLDIGEST_NONE;

  return CURLDIGEST_FINE;
}

/* convert md5 chunk to RFC2617 (section 3.1.3) -suitable ascii string*/
static void md5_to_ascii(unsigned char *source, /* 16 bytes */
                         unsigned char *dest) /* 33 bytes */
{
  int i;
  for(i=0; i<16; i++)
    snprintf((char *)&dest[i*2], 3, "%02x", source[i]);
}

CURLcode Curl_output_digest(struct connectdata *conn,
                            bool proxy,
                            const unsigned char *request,
                            const unsigned char *uripath)
{
  /* We have a Digest setup for this, use it!  Now, to get all the details for
     this sorted out, I must urge you dear friend to read up on the RFC2617
     section 3.2.2, */
  unsigned char md5buf[16]; /* 16 bytes/128 bits */
  unsigned char request_digest[33];
  unsigned char *md5this;
  unsigned char *ha1;
  unsigned char ha2[33];/* 32 digits and 1 zero byte */
  char cnoncebuf[33];
  char *cnonce = NULL;
  size_t cnonce_sz = 0;
  char *tmp = NULL;
  struct timeval now;

  char **allocuserpwd;
  const char *userp;
  const char *passwdp;
  struct auth *authp;

  struct SessionHandle *data = conn->data;
  struct digestdata *d;
  CURLcode rc;
/* The CURL_OUTPUT_DIGEST_CONV macro below is for non-ASCII machines.
   It converts digest text to ASCII so the MD5 will be correct for
   what ultimately goes over the network.
*/
#define CURL_OUTPUT_DIGEST_CONV(a, b) \
  rc = Curl_convert_to_network(a, (char *)b, strlen((const char*)b)); \
  if(rc != CURLE_OK) { \
    free(b); \
    return rc; \
  }

  if(proxy) {
    d = &data->state.proxydigest;
    allocuserpwd = &conn->allocptr.proxyuserpwd;
    userp = conn->proxyuser;
    passwdp = conn->proxypasswd;
    authp = &data->state.authproxy;
  }
  else {
    d = &data->state.digest;
    allocuserpwd = &conn->allocptr.userpwd;
    userp = conn->user;
    passwdp = conn->passwd;
    authp = &data->state.authhost;
  }

  if(*allocuserpwd) {
    Curl_safefree(*allocuserpwd);
    *allocuserpwd = NULL;
  }

  /* not set means empty */
  if(!userp)
    userp="";

  if(!passwdp)
    passwdp="";

  if(!d->nonce) {
    authp->done = FALSE;
    return CURLE_OK;
  }
  authp->done = TRUE;

  if(!d->nc)
    d->nc = 1;

  if(!d->cnonce) {
    /* Generate a cnonce */
    now = Curl_tvnow();
    snprintf(cnoncebuf, sizeof(cnoncebuf), "%32ld",
             (long)now.tv_sec + now.tv_usec);

    rc = Curl_base64_encode(data, cnoncebuf, strlen(cnoncebuf),
                            &cnonce, &cnonce_sz);
    if(rc)
      return rc;
    d->cnonce = cnonce;
  }

  /*
    if the algorithm is "MD5" or unspecified (which then defaults to MD5):

    A1 = unq(username-value) ":" unq(realm-value) ":" passwd

    if the algorithm is "MD5-sess" then:

    A1 = H( unq(username-value) ":" unq(realm-value) ":" passwd )
         ":" unq(nonce-value) ":" unq(cnonce-value)
  */

  md5this = (unsigned char *)
    aprintf("%s:%s:%s", userp, d->realm, passwdp);
  if(!md5this)
    return CURLE_OUT_OF_MEMORY;

  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
  Curl_md5it(md5buf, md5this);
  free(md5this); /* free this again */

  ha1 = malloc(33); /* 32 digits and 1 zero byte */
  if(!ha1)
    return CURLE_OUT_OF_MEMORY;

  md5_to_ascii(md5buf, ha1);

  if(d->algo == CURLDIGESTALGO_MD5SESS) {
    /* nonce and cnonce are OUTSIDE the hash */
    tmp = aprintf("%s:%s:%s", ha1, d->nonce, d->cnonce);
    if(!tmp)
      return CURLE_OUT_OF_MEMORY;
    CURL_OUTPUT_DIGEST_CONV(data, tmp); /* convert on non-ASCII machines */
    Curl_md5it(md5buf, (unsigned char *)tmp);
    free(tmp); /* free this again */
    md5_to_ascii(md5buf, ha1);
  }

  /*
    If the "qop" directive's value is "auth" or is unspecified, then A2 is:

      A2       = Method ":" digest-uri-value

          If the "qop" value is "auth-int", then A2 is:

      A2       = Method ":" digest-uri-value ":" H(entity-body)

    (The "Method" value is the HTTP request method as specified in section
    5.1.1 of RFC 2616)
  */

  /* So IE browsers < v7 cut off the URI part at the query part when they
     evaluate the MD5 and some (IIS?) servers work with them so we may need to
     do the Digest IE-style. Note that the different ways cause different MD5
     sums to get sent.

     Apache servers can be set to do the Digest IE-style automatically using
     the BrowserMatch feature:
     http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html#msie

     Further details on Digest implementation differences:
     http://www.fngtps.com/2006/09/http-authentication
  */
  if(authp->iestyle && ((tmp = strchr((char *)uripath, '?')) != NULL)) {
    md5this = (unsigned char *)aprintf("%s:%.*s", request,
                                       curlx_sztosi(tmp - (char *)uripath),
                                       uripath);
  }
  else
    md5this = (unsigned char *)aprintf("%s:%s", request, uripath);

  if(!md5this) {
    free(ha1);
    return CURLE_OUT_OF_MEMORY;
  }

  if(d->qop && Curl_raw_equal(d->qop, "auth-int")) {
    /* We don't support auth-int at the moment. I can't see a easy way to get
       entity-body here */
    /* TODO: Append H(entity-body)*/
  }
  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
  Curl_md5it(md5buf, md5this);
  free(md5this); /* free this again */
  md5_to_ascii(md5buf, ha2);

  if(d->qop) {
    md5this = (unsigned char *)aprintf("%s:%s:%08x:%s:%s:%s",
                                       ha1,
                                       d->nonce,
                                       d->nc,
                                       d->cnonce,
                                       d->qop,
                                       ha2);
  }
  else {
    md5this = (unsigned char *)aprintf("%s:%s:%s",
                                       ha1,
                                       d->nonce,
                                       ha2);
  }
  free(ha1);
  if(!md5this)
    return CURLE_OUT_OF_MEMORY;

  CURL_OUTPUT_DIGEST_CONV(data, md5this); /* convert on non-ASCII machines */
  Curl_md5it(md5buf, md5this);
  free(md5this); /* free this again */
  md5_to_ascii(md5buf, request_digest);

  /* for test case 64 (snooped from a Mozilla 1.3a request)

    Authorization: Digest username="testuser", realm="testrealm", \
    nonce="1053604145", uri="/64", response="c55f7f30d83d774a3d2dcacf725abaca"
  */

  if(d->qop) {
    *allocuserpwd =
      aprintf( "%sAuthorization: Digest "
               "username=\"%s\", "
               "realm=\"%s\", "
               "nonce=\"%s\", "
               "uri=\"%s\", "
               "cnonce=\"%s\", "
               "nc=%08x, "
               "qop=%s, "
               "response=\"%s\"",
               proxy?"Proxy-":"",
               userp,
               d->realm,
               d->nonce,
               uripath, /* this is the PATH part of the URL */
               d->cnonce,
               d->nc,
               d->qop,
               request_digest);

    if(Curl_raw_equal(d->qop, "auth"))
      d->nc++; /* The nc (from RFC) has to be a 8 hex digit number 0 padded
                  which tells to the server how many times you are using the
                  same nonce in the qop=auth mode. */
  }
  else {
    *allocuserpwd =
      aprintf( "%sAuthorization: Digest "
               "username=\"%s\", "
               "realm=\"%s\", "
               "nonce=\"%s\", "
               "uri=\"%s\", "
               "response=\"%s\"",
               proxy?"Proxy-":"",
               userp,
               d->realm,
               d->nonce,
               uripath, /* this is the PATH part of the URL */
               request_digest);
  }
  if(!*allocuserpwd)
    return CURLE_OUT_OF_MEMORY;

  /* Add optional fields */
  if(d->opaque) {
    /* append opaque */
    tmp = aprintf("%s, opaque=\"%s\"", *allocuserpwd, d->opaque);
    if(!tmp)
      return CURLE_OUT_OF_MEMORY;
    free(*allocuserpwd);
    *allocuserpwd = tmp;
  }

  if(d->algorithm) {
    /* append algorithm */
    tmp = aprintf("%s, algorithm=\"%s\"", *allocuserpwd, d->algorithm);
    if(!tmp)
      return CURLE_OUT_OF_MEMORY;
    free(*allocuserpwd);
    *allocuserpwd = tmp;
  }

  /* append CRLF + zero (3 bytes) to the userpwd header */
  tmp = realloc(*allocuserpwd, strlen(*allocuserpwd) + 3);
  if(!tmp)
    return CURLE_OUT_OF_MEMORY;
  strcat(tmp, "\r\n");
  *allocuserpwd = tmp;

  return CURLE_OK;
}

static void digest_cleanup_one(struct digestdata *d)
{
  if(d->nonce)
    free(d->nonce);
  d->nonce = NULL;

  if(d->cnonce)
    free(d->cnonce);
  d->cnonce = NULL;

  if(d->realm)
    free(d->realm);
  d->realm = NULL;

  if(d->opaque)
    free(d->opaque);
  d->opaque = NULL;

  if(d->qop)
    free(d->qop);
  d->qop = NULL;

  if(d->algorithm)
    free(d->algorithm);
  d->algorithm = NULL;

  d->nc = 0;
  d->algo = CURLDIGESTALGO_MD5; /* default algorithm */
  d->stale = FALSE; /* default means normal, not stale */
}


void Curl_digest_cleanup(struct SessionHandle *data)
{
  digest_cleanup_one(&data->state.digest);
  digest_cleanup_one(&data->state.proxydigest);
}

#endif