static void http_build_header(
  Blob *pPayload,              /* the payload that will be sent */
  Blob *pHdr,                  /* construct the header here */
  Blob *pLogin,                /* Login card header value or NULL */
  const char *zAltMimetype     /* Alternative mimetype */
){
  int nPayload = pPayload ? blob_size(pPayload) : 0;
  const char *zPath;

  blob_zero(pHdr);
  if( g.url.subpath ){
    zPath = g.url.subpath;
  }else if( g.url.path==0 || g.url.path[0]==0 ){
    zPath = "/";
  }else{
    zPath = g.url.path;
  }
  blob_appendf(pHdr, "%s %s HTTP/1.0\r\n",
               nPayload>0 ? "POST" : "GET", zPath);

  if( g.url.proxyAuth ){
    blob_appendf(pHdr, "Proxy-Authorization: %s\r\n", g.url.proxyAuth);
  }
  if( g.zHttpAuth && g.zHttpAuth[0] ){
    const char *zCredentials = g.zHttpAuth;
    char *zEncoded = encode64(zCredentials, -1);
    blob_appendf(pHdr, "Authorization: Basic %s\r\n", zEncoded);

  }

  /* Activate the PATH= auxiliary argument to the ssh command if that
  ** is called for.
  */
  if( g.url.isSsh
   && (g.url.flags & URL_SSH_RETRY)==0
   && g.db!=0
   && ssh_needs_path_argument(g.url.hostname, -1)
  ){
    g.url.flags |= URL_SSH_PATH;
  }

  if( transport_open(&g.url) ){
    fossil_warning("%s", transport_errmsg(&g.url));

        "First attempt to run fossil on %s using SSH failed.\n"
        "Retrying %s the PATH= argument.\n",
        g.url.hostname,
        (g.url.flags & URL_SSH_PATH)!=0 ? "without" : "with"
      );
      g.url.flags ^= URL_SSH_PATH|URL_SSH_RETRY;
      rc = http_exchange(pSend,pReply,mHttpFlags,0,zAltMimetype);
      if( rc==0 && g.db!=0 ){
        (void)ssh_needs_path_argument(g.url.hostname,
                                (g.url.flags & URL_SSH_PATH)!=0);
      }
      return rc;
    }else{
      /* The problem could not be corrected by retrying.  Report the
      ** the error. */

** a GET request where there is no PAYLOAD.
**
** Options:
**     --compress                 Use ZLIB compression on the payload
**     --mimetype TYPE            Mimetype of the payload
**     --no-cert-verify           Disable TLS cert verification
**     --out FILE                 Store the reply in FILE
**     --subpath PATH             HTTP request path for ssh: and file: URLs
**     -v                         Verbose output
**     --xfer                     PAYLOAD in a Fossil xfer protocol message
*/
void test_httpmsg_command(void){
  const char *zMimetype;
  const char *zInFile;
  const char *zOutFile;
  const char *zSubpath;
  Blob in, out;
  unsigned int mHttpFlags = HTTP_GENERIC|HTTP_NOCOMPRESS;

  zMimetype = find_option("mimetype",0,1);
  zOutFile = find_option("out","o",1);
  if( find_option("verbose","v",0)!=0 ) mHttpFlags |= HTTP_VERBOSE;
  if( find_option("compress",0,0)!=0 ) mHttpFlags &= ~HTTP_NOCOMPRESS;
  if( find_option("no-cert-verify",0,0)!=0 ){
    #ifdef FOSSIL_ENABLE_SSL
    ssl_disable_cert_verification();
    #endif
  }
  if( find_option("xfer",0,0)!=0 ){
    mHttpFlags |= HTTP_USE_LOGIN;
    mHttpFlags &= ~HTTP_GENERIC;
  }
  if( find_option("ipv4",0,0) ) g.fIPv4 = 1;
  zSubpath = find_option("subpath",0,1);
  verify_all_options();
  if( g.argc<3 || g.argc>5 ){
    usage("URL ?PAYLOAD? ?OUTPUT?");
  }
  zInFile = g.argc>=4 ? g.argv[3] : 0;
  if( g.argc==5 ){
    if( zOutFile ){
      fossil_fatal("output file specified twice: \"--out %s\" and \"%s\"",
        zOutFile, g.argv[4]);
    }
    zOutFile = g.argv[4];
  }
  url_parse(g.argv[2], 0);
  if( g.url.protocol[0]!='h' ){
    if( zSubpath==0 ){
      fossil_fatal("the --subpath option is required for %s://",g.url.protocol);
    }else{
      g.url.subpath = fossil_strdup(zSubpath);
    }
  }
  if( zInFile ){
    blob_read_from_file(&in, zInFile, ExtFILE);
    if( zMimetype==0 && (mHttpFlags & HTTP_GENERIC)!=0 ){
      if( fossil_strcmp(zInFile,"-")==0 ){
        zMimetype = "application/x-unknown";
      }else{