walrus.c

// -*- mode: C; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil -*-
// vim: set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:

/*
  Copyright (c) 2009  Eucalyptus Systems, Inc.

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, only version 3 of the License.

  This file is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License along
  with this program.  If not, see <http://www.gnu.org/licenses/>.

  Please contact Eucalyptus Systems, Inc., 130 Castilian
  Dr., Goleta, CA 93101 USA or visit <http://www.eucalyptus.com/licenses/>
  if you need additional information or have any questions.

  This file may incorporate work covered under the following copyright and
  permission notice:

  Software License Agreement (BSD License)

  Copyright (c) 2008, Regents of the University of California


  Redistribution and use of this software 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.

  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. USERS OF
  THIS SOFTWARE ACKNOWLEDGE THE POSSIBLE PRESENCE OF OTHER OPEN SOURCE
  LICENSED MATERIAL, COPYRIGHTED MATERIAL OR PATENTED MATERIAL IN THIS
  SOFTWARE, AND IF ANY SUCH MATERIAL IS DISCOVERED THE PARTY DISCOVERING
  IT MAY INFORM DR. RICH WOLSKI AT THE UNIVERSITY OF CALIFORNIA, SANTA
  BARBARA WHO WILL THEN ASCERTAIN THE MOST APPROPRIATE REMEDY, WHICH IN
  THE REGENTS' DISCRETION MAY INCLUDE, WITHOUT LIMITATION, REPLACEMENT
  OF THE CODE SO IDENTIFIED, LICENSING OF THE CODE SO IDENTIFIED, OR
  WITHDRAWAL OF THE CODE CAPABILITY TO THE EXTENT NEEDED TO COMPLY WITH
  ANY SUCH LICENSES OR RIGHTS.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h> /* close */
#include <assert.h>
#include <string.h>
#include <strings.h>
#include <fcntl.h> /* open */
#include <curl/curl.h>
#include <curl/easy.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#if defined(HAVE_ZLIB_H)
#include <zlib.h>
#endif
#include "euca_auth.h"
#include "eucalyptus.h"
#include "misc.h"
#include "walrus.h"

#define TOTAL_RETRIES 10 // download is retried in case of connection problems
#define FIRST_TIMEOUT 4 // in seconds, goes in powers of two afterwards
#define MAX_TIMEOUT 300 // in seconds, the cap for growing timeout values
#define CHUNK 262144 // buffer size for decompression operations
#define BUFSIZE 4096 // should be big enough for CERT and the signature
#define STRSIZE 245 // for short strings: files, hosts, URLs
#define WALRUS_ENDPOINT "/services/Walrus"
#define DEFAULT_HOST_PORT "localhost:8773"
#define GET_IMAGE_CMD "GetDecryptedImage"
#define GET_OBJECT_CMD "GetObject"

static size_t write_data      (void *buffer, size_t size, size_t nmemb, void *userp);
static size_t write_header    (void *buffer, size_t size, size_t nmemb, void *userp);
#if defined(ZLIB_VERNUM) && (ZLIB_VERNUM >= 0x1204)
static size_t write_data_zlib (void *buffer, size_t size, size_t nmemb, void *userp);
static void zerr (int ret, char * where);
#define CAN_GZIP
#endif

struct request {
    int fd; /* output file descriptor to be used by curl WRITERs */
    long long total_wrote; /* bytes written during the operation */
    long long total_calls; /* write calls made during the operation */
#if defined (CAN_GZIP)
    z_stream strm; /* stream struct used by zlib */
    int ret; /* return value of last inflate() call */
#endif
};

/* walrus_request internal lock to prevent apparent race in curl ssl dependency */
static pthread_mutex_t wreq_mutex = PTHREAD_MUTEX_INITIALIZER;

/* downloads a decrypted image from Walrus based on the manifest URL,
 * saves it to outfile */
static int walrus_request_timeout (const char * walrus_op, const char * verb, const char * requested_url, const char * outfile, const int do_compress, int connect_timeout, int total_timeout)
{
    int code = ERROR;
    char url [BUFSIZE];

    
    pthread_mutex_lock(&wreq_mutex); /* lock for curl construction */

    safe_strncpy (url, requested_url, BUFSIZE);
#if defined(CAN_GZIP)
    if (do_compress)
        snprintf (url, BUFSIZE, "%s%s", requested_url, "?IsCompressed=true");
#endif

    /* isolate the PATH in the URL as it will be needed for signing */
    char * url_path;
    if (strncasecmp (url, "http://", 7)!=0 && 
        strncasecmp (url, "https://", 8)!=0) {
        logprintfl (EUCAERROR, "{%u} walrus_request: URL must start with http(s)://...\n",(unsigned int)pthread_self());
        pthread_mutex_unlock(&wreq_mutex);
        return code;
    }
    if ((url_path=strchr(url+8, '/'))==NULL) { /* find first '/' after hostname */
        logprintfl (EUCAERROR, "{%u} walrus_request: URL has no path\n",(unsigned int)pthread_self());
        pthread_mutex_unlock(&wreq_mutex);
        return code;
    }

    if (euca_init_cert()) {
        logprintfl (EUCAERROR, "{%u} walrus_request: failed to initialize certificate\n",(unsigned int)pthread_self());
        pthread_mutex_unlock(&wreq_mutex);
        return code;
    }

    int fd = open (outfile, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR); // we do not truncate the file
    if (fd==-1 || lseek (fd, 0, SEEK_SET)==-1) {
        logprintfl (EUCAERROR, "{%u} walrus_request: failed to open %s for writing\n", (unsigned int)pthread_self(), outfile);
        pthread_mutex_unlock(&wreq_mutex);
        return code;
    }

    logprintfl(EUCADEBUG, "{%u} walrus_request: calling URL=%s\n", (unsigned int)pthread_self(), url);

    CURL * curl;
    CURLcode result;
    curl = curl_easy_init ();
    if (curl==NULL) {
        logprintfl (EUCAERROR, "{%u} walrus_request: could not initialize libcurl\n",(unsigned int)pthread_self());
        close(fd);
        pthread_mutex_unlock(&wreq_mutex);
        return code;
    }

    char error_msg [CURL_ERROR_SIZE];
    curl_easy_setopt (curl, CURLOPT_ERRORBUFFER, error_msg);
    curl_easy_setopt (curl, CURLOPT_URL, url);
    curl_easy_setopt (curl, CURLOPT_HEADERFUNCTION, write_header);
    // curl_easy_setopt (curl, CURLOPT_FOLLOWLOCATION, 1); // TODO: remove the comment once we want to follow redirects (e.g., on HTTP 407)

    if (strncmp (verb, "GET", 4)==0) {
        curl_easy_setopt (curl, CURLOPT_HTTPGET, 1L);
    } else if (strncmp (verb, "HEAD", 5)==0) {
        /* TODO: HEAD isn't very useful atm since we don't look at headers */
        curl_easy_setopt (curl, CURLOPT_NOBODY, 1L);
    } else {
        close(fd);
        logprintfl (EUCAERROR, "{%u} walrus_request: invalid HTTP verb %s\n", (unsigned int)pthread_self(), verb);
        pthread_mutex_unlock(&wreq_mutex);
        return ERROR; /* TODO: dealloc structs before returning! */
    }

	if (connect_timeout > 0) {
        curl_easy_setopt (curl, CURLOPT_CONNECTTIMEOUT, connect_timeout);
	}
	if (total_timeout > 0) {
        curl_easy_setopt (curl, CURLOPT_TIMEOUT, total_timeout);
	}

    /* set up the default write function, but possibly override
     * it below, if compression is desired and possible */
    struct request params;
    params.fd = fd;
    curl_easy_setopt (curl, CURLOPT_WRITEDATA, &params);
    curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION, write_data);
#if defined(CAN_GZIP)
    if (do_compress) {
        curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION, write_data_zlib);
    }
#endif

    struct curl_slist * headers = NULL; /* beginning of a DLL with headers */
    headers = curl_slist_append (headers, "Authorization: Euca");

    char op_hdr [STRSIZE];
    if(walrus_op != NULL) {
        snprintf (op_hdr, STRSIZE, "EucaOperation: %s", walrus_op);
        headers = curl_slist_append (headers, op_hdr);
    }

    time_t t = time(NULL);
    char date_str [26];
    if (ctime_r(&t, date_str)==NULL) {
        close(fd);
        pthread_mutex_unlock(&wreq_mutex);
        return ERROR;
    }
    assert (strlen(date_str)+7<=STRSIZE);
    char * newline = strchr (date_str, '\n');
    if (newline!=NULL) { * newline = '\0'; } // remove newline that terminates asctime() output
    char date_hdr [STRSIZE];
    snprintf (date_hdr, STRSIZE, "Date: %s", date_str);
    headers = curl_slist_append (headers, date_hdr);

    char * cert_str = euca_get_cert (0); /* read the cloud-wide cert */
    if (cert_str==NULL) {
        close(fd);
        pthread_mutex_unlock(&wreq_mutex);
        return ERROR;
    }
    char * cert64_str = base64_enc ((unsigned char *)cert_str, strlen(cert_str));
    assert (strlen(cert64_str)+11<=BUFSIZE);
    char cert_hdr [BUFSIZE];
    snprintf (cert_hdr, BUFSIZE, "EucaCert: %s", cert64_str);
    logprintfl (EUCADEBUG2, "{%u} walrus_request: base64 certificate, %s\n", (unsigned int)pthread_self(), get_string_stats(cert64_str));
    headers = curl_slist_append (headers, cert_hdr);
    free (cert64_str);
    free (cert_str);

    char * sig_str = euca_sign_url (verb, date_str, url_path); /* create Walrus-compliant sig */
    if (sig_str==NULL) {
        close(fd);
        pthread_mutex_unlock(&wreq_mutex);
        return ERROR;
    }
    assert (strlen(sig_str)+16<=BUFSIZE);
    char sig_hdr [BUFSIZE];
    snprintf (sig_hdr, BUFSIZE, "EucaSignature: %s", sig_str);
    headers = curl_slist_append (headers, sig_hdr);

    curl_easy_setopt (curl, CURLOPT_HTTPHEADER, headers); /* register headers */
    if (walrus_op) {
        logprintfl (EUCADEBUG, "{%u} walrus_request: writing %s/%s output\n", (unsigned int)pthread_self(), verb, walrus_op);
        logprintfl (EUCADEBUG, "{%u}                 from %s\n", (unsigned int)pthread_self(), url);
        logprintfl (EUCADEBUG, "{%u}                 to %s\n", (unsigned int)pthread_self(), outfile);
    } else {
        logprintfl (EUCADEBUG, "{%u} walrus_request: writing %s output to %s\n", (unsigned int)pthread_self(), verb, outfile);
    }
    int retries = TOTAL_RETRIES;
    int timeout = FIRST_TIMEOUT;
    do {
        params.total_wrote = 0L;
        params.total_calls = 0L;
#if defined(CAN_GZIP)
        if (do_compress) {
            /* allocate zlib inflate state */
            params.strm.zalloc = Z_NULL;
            params.strm.zfree = Z_NULL;
            params.strm.opaque = Z_NULL;
            params.strm.avail_in = 0;
            params.strm.next_in = Z_NULL;
            params.ret = inflateInit2 (&(params.strm), 31);
            if (params.ret != Z_OK) {
                zerr (params.ret, "walrus_request");
                break;
            }
        }
#endif

        pthread_mutex_unlock(&wreq_mutex); /* unlock for message exchange */
        result = curl_easy_perform (curl); /* do it */
        pthread_mutex_lock(&wreq_mutex); /* relock for curl teardown */
        logprintfl (EUCADEBUG, "{%u} walrus_request: wrote %lld byte(s) in %ld write(s)\n", (unsigned int)pthread_self(), params.total_wrote, params.total_calls);

#if defined(CAN_GZIP)
        if (do_compress) {
            inflateEnd(&(params.strm));
            if (params.ret != Z_STREAM_END) {
                zerr (params.ret, "walrus_request");
            }
        }
#endif

        if (result) { // curl error (connection or transfer failed)
            logprintfl (EUCAERROR,     "{%u} walrus_request: %s (%d)\n", (unsigned int)pthread_self(), error_msg, result);

        } else {
            long httpcode;
            curl_easy_getinfo (curl, CURLINFO_RESPONSE_CODE, &httpcode);
            /* TODO: pull out response message, too */

            switch (httpcode) {
            case 200L: /* all good */
                logprintfl (EUCAINFO, "{%u} walrus_request: to %s\n", (unsigned int)pthread_self(), outfile);
                code = OK;
                break;
            case 408L: /* timeout, retry */
                logprintfl (EUCAWARN, "{%u} walrus_request: server responded with HTTP code %ld (timeout)\n", (unsigned int)pthread_self(), httpcode);
                //logcat (EUCADEBUG, outfile); /* dump the error from outfile into the log */
                break;
            default: /* some kind of error */
                logprintfl (EUCAERROR, "{%u} walrus_request: server responded with HTTP code %ld\n", (unsigned int)pthread_self(), httpcode);
                //logcat (EUCADEBUG, outfile); /* dump the error from outfile into the log */
                retries=0;
            }
        }

        if (code!=OK && retries>0) {
            logprintfl (EUCAERROR, "                  download retry %d of %d will commence in %d seconds\n", retries, TOTAL_RETRIES, timeout);
            sleep (timeout);
            lseek (fd, 0L, SEEK_SET);
            timeout <<= 1;
            if (timeout > MAX_TIMEOUT)
                timeout = MAX_TIMEOUT;
        }

        retries--;
    } while (code!=OK && retries>0);
    close (fd);

    if ( code != OK ) {
        logprintfl (EUCAINFO, "{%u} walrus_request: due to error, removing %s\n", (unsigned int)pthread_self(), outfile);
        remove (outfile);
    }

    free (sig_str);
    curl_slist_free_all (headers);
    curl_easy_cleanup (curl);
    pthread_mutex_unlock(&wreq_mutex);
    return code;
}

#if 0
/* Unused function */
static int walrus_request (const char * walrus_op, const char * verb, const char * requested_url, const char * outfile, const int do_compress)
{
    return (walrus_request_timeout(walrus_op, verb, requested_url, outfile, do_compress, 0, 0));
}
#endif /* 0 */

/* downloads a Walrus object from the URL, saves it to outfile */
int walrus_object_by_url (const char * url, const char * outfile, const int do_compress)
{
    return walrus_request_timeout (NULL, "GET", url, outfile, do_compress, 120, 0);
}

/* downloads a Walrus object from the default Walrus endpoint,
 * so only the path is needed; saves object to outfile */
int walrus_object_by_path (const char * path, const char * outfile, const int do_compress)
{
    char url [STRSIZE];
    snprintf (url, STRSIZE, "http://%s%s/%s", DEFAULT_HOST_PORT, WALRUS_ENDPOINT, path);
    return walrus_object_by_url (url, outfile, do_compress);
}

/* downloads a decrypted image from Walrus based on the manifest URL,
 * saves it to outfile */
int walrus_image_by_manifest_url (const char * url, const char * outfile, const int do_compress)
{
    return walrus_request_timeout (GET_IMAGE_CMD, "GET", url, outfile, do_compress, 120, 0);
}

/* gets a decrypted image from the default Walrus endpoint,
 * so only manifest path is needed; saves image to outfile */
int walrus_image_by_manifest_path (const char * manifest_path, const char * outfile, const int do_compress)
{
    char url [STRSIZE];
    snprintf (url, STRSIZE, "http://%s%s/%s", DEFAULT_HOST_PORT, WALRUS_ENDPOINT, manifest_path);
    return walrus_image_by_manifest_url (url, outfile, do_compress);
}

// downloads a digest and returns it as a new string (or NULL if error)
// that the caller must free
char * walrus_get_digest (const char * url)
{
    char * digest_str = NULL;
    char * digest_path = strdup ("/tmp/walrus-digest-XXXXXX");

    if(!digest_path) {
       logprintfl (EUCAERROR, "{%u} error: failed to strdup digest path\n", (unsigned int)pthread_self());
       return digest_path;
    }

    int tmp_fd = safe_mkstemp (digest_path);
    if (tmp_fd<0) {
        logprintfl (EUCAERROR, "{%u} error: failed to create a digest file %s\n", (unsigned int)pthread_self(), digest_path);
    } else {
        close (tmp_fd); // walrus_ routine will reopen the file

        // download a fresh digest
        if (walrus_object_by_url (url, digest_path, 0) != 0 ) {
            logprintfl (EUCAERROR, "{%u} error: failed to download digest to %s\n", (unsigned int)pthread_self(), digest_path);
        } else {
            digest_str = file2strn (digest_path, 2000000);
        }
        unlink (digest_path);
    }
    if(digest_path) {
        free(digest_path);
    }
    return digest_str;
}

/* downloads a digest of an image and compares it to file at old_digest_path
 * returns 0 if same, -N if different, N if error */
int walrus_verify_digest (const char * url, const char * old_digest_path)
{
    int e = ERROR;

    char * new_digest;
    char * old_digest = file2strn (old_digest_path, 2000000);
    if (old_digest == NULL) {
        logprintfl (EUCAERROR, "{%u} error: failed to read old digest %s\n", (unsigned int)pthread_self(), old_digest_path);
        return e;
    }

    if ((new_digest=walrus_get_digest (url)) != NULL) {
        // compare the two
        if (strcmp (new_digest, old_digest)) {
            e = -1;
        } else {
            e = 0;
        }

        free (new_digest);
    }
    free (old_digest);

    return e;
}

/* libcurl header write handler */
static size_t write_header (void *buffer, size_t size, size_t nmemb, void *params)
{
    /* here in case we want to do something with headers */
    return size * nmemb;
}

/* libcurl write handler */
static size_t write_data (void *buffer, size_t size, size_t nmemb, void *params)
{
    assert (params !=NULL);
    int fd = ((struct request *)params)->fd;
    int wrote = write (fd, buffer, size * nmemb);
    ((struct request *)params)->total_wrote += wrote;
    ((struct request *)params)->total_calls++;

    return wrote;
}

#if defined(CAN_GZIP)

/* unused testing function */
static void print_data (unsigned char *buf, const int size)
{
    int i;

    for (i=0; i<size; i++) {
        int c = buf [i];
        if (c>' ' && c<='~')
            printf (" %c", c);
        else
            printf (" %x", c);
    }
    printf ("\n");
}

/* report on a zlib error */
static void zerr (int ret, char * where)
{
    switch (ret) {
    case Z_ERRNO:
        logprintfl (EUCAERROR, "{%u} error: %s: zlib: failed to write\n", (unsigned int)pthread_self(), where);
        break;
    case Z_STREAM_ERROR:
        logprintfl (EUCAERROR, "{%u} error: %s: zlib: invalid compression level\n", (unsigned int)pthread_self(), where);
        break;
    case Z_DATA_ERROR:
        logprintfl (EUCAERROR, "{%u} error: %s: zlib: invalid or incomplete deflate data\n", (unsigned int)pthread_self(), where);
        break;
    case Z_MEM_ERROR:
        logprintfl (EUCAERROR, "{%u} error: %s: zlib: out of memory\n", (unsigned int)pthread_self(), where);
        break;
    case Z_VERSION_ERROR:
        logprintfl (EUCAERROR, "{%u} error: %s: zlib: zlib version mismatch!\n", (unsigned int)pthread_self(), where);
    }
}

/* libcurl write handler for gzipped streams */
static size_t write_data_zlib (void *buffer, size_t size, size_t nmemb, void *params)
{
    assert (params !=NULL);
    z_stream * strm = &(((struct request *)params)->strm);
    int fd = ((struct request *)params)->fd;
    unsigned char out [CHUNK];
    int wrote = 0;
    int ret;

    strm->avail_in = size * nmemb;
    strm->next_in = (unsigned char *)buffer;
    do {
        strm->avail_out = CHUNK;
        strm->next_out = out;

        ((struct request *)params)->ret = ret = inflate (strm, Z_NO_FLUSH);
        switch (ret) {
        case Z_NEED_DICT:
            ret = Z_DATA_ERROR; // ok to fall through
        case Z_DATA_ERROR:
        case Z_MEM_ERROR:
        case Z_STREAM_ERROR:
            inflateEnd(strm);
            zerr (ret, "write_data_zlib");
            return ret;
        }

        unsigned have = CHUNK - strm->avail_out;
        if (write (fd, out, have) != have) {
            logprintfl (EUCAERROR, "{%u} error: write_data_zlib: failed to write\n", (unsigned int)pthread_self());
            inflateEnd(strm);
            return Z_ERRNO;
        }
        wrote += have;
    } while (strm->avail_out == 0);

    ((struct request *)params)->total_wrote += wrote;
    ((struct request *)params)->total_calls++;
    return size * nmemb;
}

#endif /* CAN_GZIP */