Something

struct FirewallConfig *insertElem (struct ConfigEntry *entry, struct FirewallConfig *tree, int *errno) {  if (tree != NULL) {	int r = compareEntry(entry, tree->entry);    if (r == 0) {      *errno = ALREADY_IN_TREE;      return (NULL);    }    if (r < 0)       tree->left = insertElem (entry, tree->left, errno);    else       tree->right = insertElem (entry, tree->right, errno);  }  else {    /* create a new leaf */    tree = malloc (sizeof (struct FirewallConfig));    if (!tree) {      *errno = OUT_OF_MEMORY;      return (NULL);    }        tree->entry = entry;    tree->left = NULL;    tree->right = NULL;  }  return tree;}struct FirewallConfig {  struct ConfigEntry *entry;  struct FirewallConfig *left;  struct FirewallConfig *right;};int compareEntry (struct ConfigEntry *entry1, struct ConfigEntry *entry2) {    int result;   result = strCompare (entry1->uid, entry2->uid);  if (result != 0 ) {    return result;  }   result = strCompare (entry1->program, entry2->program);  if (result != 0 ) {    return result;  }   result = strCompare (entry1->IPAddress, entry2->IPAddress);  if (result != 0 ) {    return result;  }   if (entry1->port < entry2->port)     return -1;  else if (entry1->port > entry2->port)     return 1;  else     return 0; }