Commit message: cookie: fix tailmatching to prevent cross-domain leakage

Cookies set for 'example.com' could accidentaly also be sent by libcurl
to the 'bexample.com' (ie with a prefix to the first domain name).

This is a security vulnerabilty, CVE-2013-1944.

Bug: http://curl.haxx.se/docs/adv_20130412.html
CVE: CVE-2013-1944
CWE: CWE-200
Vulnerability description: The tailMatch function in cookie.c in cURL and libcurl before 7.30.0 does not properly match the path domain when sending cookies, which allows remote attackers to steal cookies via a matching suffix in the domain of a URL.

Project: curl
File: cookie.c

Curl_cookie_add(struct SessionHandle *data,
                /* The 'data' pointer here may be NULL at times, and thus
                   must only be used very carefully for things that can deal
                   with data being NULL. Such as infof() and similar */

                struct CookieInfo *c,
                bool httpheader, /* TRUE if HTTP header-style line */
                char *lineptr,   /* first character of the line */
                const char *domain, /* default domain */
                const char *path)   /* full path used when this cookie is set,
                                       used to get default path for the cookie
                                       unless set */
{
  struct Cookie *clist;
  char name[MAX_NAME];
  struct Cookie *co;
  struct Cookie *lastc=NULL;
  time_t now = time(NULL);
  bool replace_old = FALSE;
  bool badcookie = FALSE; /* cookies are good by default. mmmmm yummy */

#ifdef CURL_DISABLE_VERBOSE_STRINGS
  (void)data;
#endif

  /* First, alloc and init a new struct for it */
  co = calloc(1, sizeof(struct Cookie));
  if(!co)
    return NULL; /* bail out if we're this low on memory */

  if(httpheader) {
    /* This line was read off a HTTP-header */
    const char *ptr;
    const char *semiptr;
    char *what;

    what = malloc(MAX_COOKIE_LINE);
    if(!what) {
      free(co);
      return NULL;
    }

    semiptr=strchr(lineptr, ';'); /* first, find a semicolon */

    while(*lineptr && ISBLANK(*lineptr))
      lineptr++;

    ptr = lineptr;
    do {
      /* we have a <what>=<this> pair or a stand-alone word here */
      name[0]=what[0]=0; /* init the buffers */
      if(1 <= sscanf(ptr, "%" MAX_NAME_TXT "[^;\r\n =]=%"
                     MAX_COOKIE_LINE_TXT "[^;\r\n]",
                     name, what)) {
        /* Use strstore() below to properly deal with received cookie
           headers that have the same string property set more than once,
           and then we use the last one. */
        const char *whatptr;
        bool done = FALSE;
        bool sep;
        size_t len=strlen(what);
        const char *endofn = &ptr[ strlen(name) ];

        /* skip trailing spaces in name */
        while(*endofn && ISBLANK(*endofn))
          endofn++;

        /* name ends with a '=' ? */
        sep = (*endofn == '=')?TRUE:FALSE;

        /* Strip off trailing whitespace from the 'what' */
        while(len && ISBLANK(what[len-1])) {
          what[len-1]=0;
          len--;
        }

        /* Skip leading whitespace from the 'what' */
        whatptr=what;
        while(*whatptr && ISBLANK(*whatptr))
          whatptr++;

        if(!len) {
          /* this was a "<name>=" with no content, and we must allow
             'secure' and 'httponly' specified this weirdly */
          done = TRUE;
          if(Curl_raw_equal("secure", name))
            co->secure = TRUE;
          else if(Curl_raw_equal("httponly", name))
            co->httponly = TRUE;
          else if(sep)
            /* there was a '=' so we're not done parsing this field */
            done = FALSE;
        }
        if(done)
          ;
        else if(Curl_raw_equal("path", name)) {
          strstore(&co->path, whatptr);
          if(!co->path) {
            badcookie = TRUE; /* out of memory bad */
            break;
          }
        }
        else if(Curl_raw_equal("domain", name)) {
          /* note that this name may or may not have a preceding dot, but
             we don't care about that, we treat the names the same anyway */

          const char *domptr=whatptr;
          const char *nextptr;
          int dotcount=1;

          /* Count the dots, we need to make sure that there are enough
             of them. */

          if('.' == whatptr[0])
            /* don't count the initial dot, assume it */
            domptr++;

          do {
            nextptr = strchr(domptr, '.');
            if(nextptr) {
              if(domptr != nextptr)
                dotcount++;
              domptr = nextptr+1;
            }
          } while(nextptr);

          /* The original Netscape cookie spec defined that this domain name
             MUST have three dots (or two if one of the seven holy TLDs),
             but it seems that these kinds of cookies are in use "out there"
             so we cannot be that strict. I've therefore lowered the check
             to not allow less than two dots. */

          if(dotcount < 2) {
            /* Received and skipped a cookie with a domain using too few
               dots. */
            badcookie=TRUE; /* mark this as a bad cookie */
            infof(data, "skipped cookie with illegal dotcount domain: %s\n",
                  whatptr);
          }
          else {
            /* Now, we make sure that our host is within the given domain,
               or the given domain is not valid and thus cannot be set. */

            if('.' == whatptr[0])
              whatptr++; /* ignore preceding dot */

            if(!domain || tailmatch(whatptr, domain)) {
              const char *tailptr=whatptr;
              if(tailptr[0] == '.')
                tailptr++;
              strstore(&co->domain, tailptr); /* don't prefix w/dots
                                                 internally */
              if(!co->domain) {
                badcookie = TRUE;
                break;
              }
              co->tailmatch=TRUE; /* we always do that if the domain name was
                                     given */
            }
            else {
              /* we did not get a tailmatch and then the attempted set domain
                 is not a domain to which the current host belongs. Mark as
                 bad. */
              badcookie=TRUE;
              infof(data, "skipped cookie with bad tailmatch domain: %s\n",
                    whatptr);
            }
          }
        }
        else if(Curl_raw_equal("version", name)) {
          strstore(&co->version, whatptr);
          if(!co->version) {
            badcookie = TRUE;
            break;
          }
        }
        else if(Curl_raw_equal("max-age", name)) {
          /* Defined in RFC2109:

             Optional.  The Max-Age attribute defines the lifetime of the
             cookie, in seconds.  The delta-seconds value is a decimal non-
             negative integer.  After delta-seconds seconds elapse, the
             client should discard the cookie.  A value of zero means the
             cookie should be discarded immediately.

          */
          strstore(&co->maxage, whatptr);
          if(!co->maxage) {
            badcookie = TRUE;
            break;
          }
          co->expires =
            strtol((*co->maxage=='\"')?&co->maxage[1]:&co->maxage[0],NULL,10)
            + (long)now;
        }
        else if(Curl_raw_equal("expires", name)) {
          strstore(&co->expirestr, whatptr);
          if(!co->expirestr) {
            badcookie = TRUE;
            break;
          }
          /* Note that if the date couldn't get parsed for whatever reason,
             the cookie will be treated as a session cookie */
          co->expires = curl_getdate(what, &now);

          /* Session cookies have expires set to 0 so if we get that back
             from the date parser let's add a second to make it a
             non-session cookie */
          if(co->expires == 0)
            co->expires = 1;
          else if(co->expires < 0)
            co->expires = 0;
        }
        else if(!co->name) {
          co->name = strdup(name);
          co->value = strdup(whatptr);
          if(!co->name || !co->value) {
            badcookie = TRUE;
            break;
          }
        }
        /*
          else this is the second (or more) name we don't know
          about! */
      }
      else {
        /* this is an "illegal" <what>=<this> pair */
      }

      if(!semiptr || !*semiptr) {
        /* we already know there are no more cookies */
        semiptr = NULL;
        continue;
      }

      ptr=semiptr+1;
      while(*ptr && ISBLANK(*ptr))
        ptr++;
      semiptr=strchr(ptr, ';'); /* now, find the next semicolon */

      if(!semiptr && *ptr)
        /* There are no more semicolons, but there's a final name=value pair
           coming up */
        semiptr=strchr(ptr, '\0');
    } while(semiptr);

    if(!badcookie && !co->domain) {
      if(domain) {
        /* no domain was given in the header line, set the default */
        co->domain=strdup(domain);
        if(!co->domain)
          badcookie = TRUE;
      }
    }

    if(!badcookie && !co->path && path) {
      /* No path was given in the header line, set the default.
         Note that the passed-in path to this function MAY have a '?' and
         following part that MUST not be stored as part of the path. */
      char *queryp = strchr(path, '?');

      /* queryp is where the interesting part of the path ends, so now we
         want to the find the last */
      char *endslash;
      if(!queryp)
        endslash = strrchr(path, '/');
      else
        endslash = memrchr(path, '/', (size_t)(queryp - path));
      if(endslash) {
        size_t pathlen = (size_t)(endslash-path+1); /* include ending slash */
        co->path=malloc(pathlen+1); /* one extra for the zero byte */
        if(co->path) {
          memcpy(co->path, path, pathlen);
          co->path[pathlen]=0; /* zero terminate */
        }
        else
          badcookie = TRUE;
      }
    }

    free(what);

    if(badcookie || !co->name) {
      /* we didn't get a cookie name or a bad one,
         this is an illegal line, bail out */
      freecookie(co);
      return NULL;
    }

  }
  else {
    /* This line is NOT a HTTP header style line, we do offer support for
       reading the odd netscape cookies-file format here */
    char *ptr;
    char *firstptr;
    char *tok_buf=NULL;
    int fields;

    /* IE introduced HTTP-only cookies to prevent XSS attacks. Cookies
       marked with httpOnly after the domain name are not accessible
       from javascripts, but since curl does not operate at javascript
       level, we include them anyway. In Firefox's cookie files, these
       lines are preceded with #HttpOnly_ and then everything is
       as usual, so we skip 10 characters of the line..
    */
    if(strncmp(lineptr, "#HttpOnly_", 10) == 0) {
      lineptr += 10;
      co->httponly = TRUE;
    }

    if(lineptr[0]=='#') {
      /* don't even try the comments */
      free(co);
      return NULL;
    }
    /* strip off the possible end-of-line characters */
    ptr=strchr(lineptr, '\r');
    if(ptr)
      *ptr=0; /* clear it */
    ptr=strchr(lineptr, '\n');
    if(ptr)
      *ptr=0; /* clear it */

    firstptr=strtok_r(lineptr, "\t", &tok_buf); /* tokenize it on the TAB */

    /* Here's a quick check to eliminate normal HTTP-headers from this */
    if(!firstptr || strchr(firstptr, ':')) {
      free(co);
      return NULL;
    }

    /* Now loop through the fields and init the struct we already have
       allocated */
    for(ptr=firstptr, fields=0; ptr && !badcookie;
        ptr=strtok_r(NULL, "\t", &tok_buf), fields++) {
      switch(fields) {
      case 0:
        if(ptr[0]=='.') /* skip preceding dots */
          ptr++;
        co->domain = strdup(ptr);
        if(!co->domain)
          badcookie = TRUE;
        break;
      case 1:
        /* This field got its explanation on the 23rd of May 2001 by
           Andrs Garca:

           flag: A TRUE/FALSE value indicating if all machines within a given
           domain can access the variable. This value is set automatically by
           the browser, depending on the value you set for the domain.

           As far as I can see, it is set to true when the cookie says
           .domain.com and to false when the domain is complete www.domain.com
        */
        co->tailmatch = Curl_raw_equal(ptr, "TRUE")?TRUE:FALSE;
        break;
      case 2:
        /* It turns out, that sometimes the file format allows the path
           field to remain not filled in, we try to detect this and work
           around it! Andrs Garca made us aware of this... */
        if(strcmp("TRUE", ptr) && strcmp("FALSE", ptr)) {
          /* only if the path doesn't look like a boolean option! */
          co->path = strdup(ptr);
          if(!co->path)
            badcookie = TRUE;
          break;
        }
        /* this doesn't look like a path, make one up! */
        co->path = strdup("/");
        if(!co->path)
          badcookie = TRUE;
        fields++; /* add a field and fall down to secure */
        /* FALLTHROUGH */
      case 3:
        co->secure = Curl_raw_equal(ptr, "TRUE")?TRUE:FALSE;
        break;
      case 4:
        co->expires = curlx_strtoofft(ptr, NULL, 10);
        break;
      case 5:
        co->name = strdup(ptr);
        if(!co->name)
          badcookie = TRUE;
        break;
      case 6:
        co->value = strdup(ptr);
        if(!co->value)
          badcookie = TRUE;
        break;
      }
    }
    if(6 == fields) {
      /* we got a cookie with blank contents, fix it */
      co->value = strdup("");
      if(!co->value)
        badcookie = TRUE;
      else
        fields++;
    }

    if(!badcookie && (7 != fields))
      /* we did not find the sufficient number of fields */
      badcookie = TRUE;

    if(badcookie) {
      freecookie(co);
      return NULL;
    }

  }

  if(!c->running &&    /* read from a file */
     c->newsession &&  /* clean session cookies */
     !co->expires) {   /* this is a session cookie since it doesn't expire! */
    freecookie(co);
    return NULL;
  }

  co->livecookie = c->running;

  /* now, we have parsed the incoming line, we must now check if this
     superceeds an already existing cookie, which it may if the previous have
     the same domain and path as this */

  clist = c->cookies;
  replace_old = FALSE;
  while(clist) {
    if(Curl_raw_equal(clist->name, co->name)) {
      /* the names are identical */

      if(clist->domain && co->domain) {
        if(Curl_raw_equal(clist->domain, co->domain))
          /* The domains are identical */
          replace_old=TRUE;
      }
      else if(!clist->domain && !co->domain)
        replace_old = TRUE;

      if(replace_old) {
        /* the domains were identical */

        if(clist->path && co->path) {
          if(Curl_raw_equal(clist->path, co->path)) {
            replace_old = TRUE;
          }
          else
            replace_old = FALSE;
        }
        else if(!clist->path && !co->path)
          replace_old = TRUE;
        else
          replace_old = FALSE;

      }

      if(replace_old && !co->livecookie && clist->livecookie) {
        /* Both cookies matched fine, except that the already present
           cookie is "live", which means it was set from a header, while
           the new one isn't "live" and thus only read from a file. We let
           live cookies stay alive */

        /* Free the newcomer and get out of here! */
        freecookie(co);
        return NULL;
      }

      if(replace_old) {
        co->next = clist->next; /* get the next-pointer first */

        /* then free all the old pointers */
        free(clist->name);
        if(clist->value)
          free(clist->value);
        if(clist->domain)
          free(clist->domain);
        if(clist->path)
          free(clist->path);
        if(clist->expirestr)
          free(clist->expirestr);

        if(clist->version)
          free(clist->version);
        if(clist->maxage)
          free(clist->maxage);

        *clist = *co;  /* then store all the new data */

        free(co);   /* free the newly alloced memory */
        co = clist; /* point to the previous struct instead */

        /* We have replaced a cookie, now skip the rest of the list but
           make sure the 'lastc' pointer is properly set */
        do {
          lastc = clist;
          clist = clist->next;
        } while(clist);
        break;
      }
    }
    lastc = clist;
    clist = clist->next;
  }

  if(c->running)
    /* Only show this when NOT reading the cookies from a file */
    infof(data, "%s cookie %s=\"%s\" for domain %s, path %s, "
          "expire %" FORMAT_OFF_T "\n",
          replace_old?"Replaced":"Added", co->name, co->value,
          co->domain, co->path, co->expires);

  if(!replace_old) {
    /* then make the last item point on this new one */
    if(lastc)
      lastc->next = co;
    else
      c->cookies = co;
    c->numcookies++; /* one more cookie in the jar */
  }

  return co;
}

Project: curl
File: cookie.c

void Curl_cookie_cleanup(struct CookieInfo *c)
{
  struct Cookie *co;
  struct Cookie *next;
  if(c) {
    if(c->filename)
      free(c->filename);
    co = c->cookies;

    while(co) {
      next = co->next;
      freecookie(co);
      co = next;
    }
    free(c); /* free the base struct as well */
  }
}

Project: curl
File: cookie.c

void Curl_cookie_clearall(struct CookieInfo *cookies)
{
  if(cookies) {
    Curl_cookie_freelist(cookies->cookies, TRUE);
    cookies->cookies = NULL;
    cookies->numcookies = 0;
  }
}

Project: curl
File: cookie.c

void Curl_cookie_clearsess(struct CookieInfo *cookies)
{
  struct Cookie *first, *curr, *next, *prev = NULL;

  if(!cookies || !cookies->cookies)
    return;

  first = curr = prev = cookies->cookies;

  for(; curr; curr = next) {
    next = curr->next;
    if(!curr->expires) {
      if(first == curr)
        first = next;

      if(prev == curr)
        prev = next;
      else
        prev->next = next;

      freecookie(curr);
      cookies->numcookies--;
    }
    else
      prev = curr;
  }

  cookies->cookies = first;
}

Project: curl
File: cookie.c

void Curl_cookie_freelist(struct Cookie *co, bool cookiestoo)
{
  struct Cookie *next;
  if(co) {
    while(co) {
      next = co->next;
      if(cookiestoo)
        freecookie(co);
      else
        free(co); /* we only free the struct since the "members" are all just
                     pointed out in the main cookie list! */
      co = next;
    }
  }
}

Project: curl
File: cookie.c

struct Cookie *Curl_cookie_getlist(struct CookieInfo *c,
                                   const char *host, const char *path,
                                   bool secure)
{
  struct Cookie *newco;
  struct Cookie *co;
  time_t now = time(NULL);
  struct Cookie *mainco=NULL;
  size_t matches = 0;

  if(!c || !c->cookies)
    return NULL; /* no cookie struct or no cookies in the struct */

  co = c->cookies;

  while(co) {
    /* only process this cookie if it is not expired or had no expire
       date AND that if the cookie requires we're secure we must only
       continue if we are! */
    if((!co->expires || (co->expires > now)) &&
       (co->secure?secure:TRUE)) {

      /* now check if the domain is correct */
      if(!co->domain ||
         (co->tailmatch && tailmatch(co->domain, host)) ||
         (!co->tailmatch && Curl_raw_equal(host, co->domain)) ) {
        /* the right part of the host matches the domain stuff in the
           cookie data */

        /* now check the left part of the path with the cookies path
           requirement */
        if(!co->path ||
           /* not using checkprefix() because matching should be
              case-sensitive */
           !strncmp(co->path, path, strlen(co->path)) ) {

          /* and now, we know this is a match and we should create an
             entry for the return-linked-list */

          newco = malloc(sizeof(struct Cookie));
          if(newco) {
            /* first, copy the whole source cookie: */
            memcpy(newco, co, sizeof(struct Cookie));

            /* then modify our next */
            newco->next = mainco;

            /* point the main to us */
            mainco = newco;

            matches++;
          }
          else {
            fail:
            /* failure, clear up the allocated chain and return NULL */
            while(mainco) {
              co = mainco->next;
              free(mainco);
              mainco = co;
            }

            return NULL;
          }
        }
      }
    }
    co = co->next;
  }

  if(matches) {
    /* Now we need to make sure that if there is a name appearing more than
       once, the longest specified path version comes first. To make this
       the swiftest way, we just sort them all based on path length. */
    struct Cookie **array;
    size_t i;

    /* alloc an array and store all cookie pointers */
    array = malloc(sizeof(struct Cookie *) * matches);
    if(!array)
      goto fail;

    co = mainco;

    for(i=0; co; co = co->next)
      array[i++] = co;

    /* now sort the cookie pointers in path length order */
    qsort(array, matches, sizeof(struct Cookie *), cookie_sort);

    /* remake the linked list order according to the new order */

    mainco = array[0]; /* start here */
    for(i=0; i<matches-1; i++)
      array[i]->next = array[i+1];
    array[matches-1]->next = NULL; /* terminate the list */

    free(array); /* remove the temporary data again */
  }

  return mainco; /* return the new list */
}

Project: curl
File: cookie.c

struct CookieInfo *Curl_cookie_init(struct SessionHandle *data,
                                    const char *file,
                                    struct CookieInfo *inc,
                                    bool newsession)
{
  struct CookieInfo *c;
  FILE *fp;
  bool fromfile=TRUE;

  if(NULL == inc) {
    /* we didn't get a struct, create one */
    c = calloc(1, sizeof(struct CookieInfo));
    if(!c)
      return NULL; /* failed to get memory */
    c->filename = strdup(file?file:"none"); /* copy the name just in case */
  }
  else {
    /* we got an already existing one, use that */
    c = inc;
  }
  c->running = FALSE; /* this is not running, this is init */

  if(file && strequal(file, "-")) {
    fp = stdin;
    fromfile=FALSE;
  }
  else if(file && !*file) {
    /* points to a "" string */
    fp = NULL;
  }
  else
    fp = file?fopen(file, "r"):NULL;

  c->newsession = newsession; /* new session? */

  if(fp) {
    char *lineptr;
    bool headerline;

    char *line = malloc(MAX_COOKIE_LINE);
    if(line) {
      while(fgets(line, MAX_COOKIE_LINE, fp)) {
        if(checkprefix("Set-Cookie:", line)) {
          /* This is a cookie line, get it! */
          lineptr=&line[11];
          headerline=TRUE;
        }
        else {
          lineptr=line;
          headerline=FALSE;
        }
        while(*lineptr && ISBLANK(*lineptr))
          lineptr++;

        Curl_cookie_add(data, c, headerline, lineptr, NULL, NULL);
      }
      free(line); /* free the line buffer */
    }
    if(fromfile)
      fclose(fp);
  }

  c->running = TRUE;          /* now, we're running */

  return c;
}

Project: curl
File: cookie.c

struct curl_slist *Curl_cookie_list(struct SessionHandle *data)
{
  struct curl_slist *list = NULL;
  struct curl_slist *beg;
  struct Cookie *c;
  char *line;

  if((data->cookies == NULL) ||
      (data->cookies->numcookies == 0))
    return NULL;

  c = data->cookies->cookies;

  while(c) {
    /* fill the list with _all_ the cookies we know */
    line = get_netscape_format(c);
    if(!line) {
      curl_slist_free_all(list);
      return NULL;
    }
    beg = curl_slist_append(list, line);
    free(line);
    if(!beg) {
      curl_slist_free_all(list);
      return NULL;
    }
    list = beg;
    c = c->next;
  }

  return list;
}

Project: curl
File: cookie.c

void Curl_flush_cookies(struct SessionHandle *data, int cleanup)
{
  if(data->set.str[STRING_COOKIEJAR]) {
    if(data->change.cookielist) {
      /* If there is a list of cookie files to read, do it first so that
         we have all the told files read before we write the new jar.
         Curl_cookie_loadfiles() LOCKS and UNLOCKS the share itself! */
      Curl_cookie_loadfiles(data);
    }

    Curl_share_lock(data, CURL_LOCK_DATA_COOKIE, CURL_LOCK_ACCESS_SINGLE);

    /* if we have a destination file for all the cookies to get dumped to */
    if(cookie_output(data->cookies, data->set.str[STRING_COOKIEJAR]))
      infof(data, "WARNING: failed to save cookies in %s\n",
            data->set.str[STRING_COOKIEJAR]);
  }
  else {
    if(cleanup && data->change.cookielist) {
      /* since nothing is written, we can just free the list of cookie file
         names */
      curl_slist_free_all(data->change.cookielist); /* clean up list */
      data->change.cookielist = NULL;
    }
    Curl_share_lock(data, CURL_LOCK_DATA_COOKIE, CURL_LOCK_ACCESS_SINGLE);
  }

  if(cleanup && (!data->share || (data->cookies != data->share->cookies))) {
    Curl_cookie_cleanup(data->cookies);
  }
  Curl_share_unlock(data, CURL_LOCK_DATA_COOKIE);
}

Project: curl
File: cookie.c

static int cookie_output(struct CookieInfo *c, const char *dumphere)
{
  struct Cookie *co;
  FILE *out;
  bool use_stdout=FALSE;

  if((NULL == c) || (0 == c->numcookies))
    /* If there are no known cookies, we don't write or even create any
       destination file */
    return 0;

  if(strequal("-", dumphere)) {
    /* use stdout */
    out = stdout;
    use_stdout=TRUE;
  }
  else {
    out = fopen(dumphere, "w");
    if(!out)
      return 1; /* failure */
  }

  if(c) {
    char *format_ptr;

    fputs("# Netscape HTTP Cookie File\n"
          "# http://curl.haxx.se/docs/http-cookies.html\n"
          "# This file was generated by libcurl! Edit at your own risk.\n\n",
          out);
    co = c->cookies;

    while(co) {
      format_ptr = get_netscape_format(co);
      if(format_ptr == NULL) {
        fprintf(out, "#\n# Fatal libcurl error\n");
        if(!use_stdout)
          fclose(out);
        return 1;
      }
      fprintf(out, "%s\n", format_ptr);
      free(format_ptr);
      co=co->next;
    }
  }

  if(!use_stdout)
    fclose(out);

  return 0;
}

Project: curl
File: cookie.c

static int cookie_sort(const void *p1, const void *p2)
{
  struct Cookie *c1 = *(struct Cookie **)p1;
  struct Cookie *c2 = *(struct Cookie **)p2;
  size_t l1, l2;

  /* 1 - compare cookie path lengths */
  l1 = c1->path ? strlen(c1->path) : 0;
  l2 = c2->path ? strlen(c2->path) : 0;

  if(l1 != l2)
    return (l2 > l1) ? 1 : -1 ; /* avoid size_t <=> int conversions */

  /* 2 - compare cookie domain lengths */
  l1 = c1->domain ? strlen(c1->domain) : 0;
  l2 = c2->domain ? strlen(c2->domain) : 0;

  if(l1 != l2)
    return (l2 > l1) ? 1 : -1 ;  /* avoid size_t <=> int conversions */

  /* 3 - compare cookie names */
  if(c1->name && c2->name)
    return strcmp(c1->name, c2->name);

  /* sorry, can't be more deterministic */
  return 0;
}

Project: curl
File: cookie.c

static char *get_netscape_format(const struct Cookie *co)
{
  return aprintf(
    "%s"     /* httponly preamble */
    "%s%s\t" /* domain */
    "%s\t"   /* tailmatch */
    "%s\t"   /* path */
    "%s\t"   /* secure */
    "%" FORMAT_OFF_T "\t"   /* expires */
    "%s\t"   /* name */
    "%s",    /* value */
    co->httponly?"#HttpOnly_":"",
    /* Make sure all domains are prefixed with a dot if they allow
       tailmatching. This is Mozilla-style. */
    (co->tailmatch && co->domain && co->domain[0] != '.')? ".":"",
    co->domain?co->domain:"unknown",
    co->tailmatch?"TRUE":"FALSE",
    co->path?co->path:"/",
    co->secure?"TRUE":"FALSE",
    co->expires,
    co->name,
    co->value?co->value:"");
}

Project: curl
File: cookie.c

static void strstore(char **str, const char *newstr)
{
  if(*str)
    free(*str);
  *str = strdup(newstr);
}