C doubly linked circular list insert -

doesn't insert , doesn't keep adresses of next , prev node: i'm trying read input file; can read data corectly , based on every line, creates aeronava object. seems insert doesn't work.any suggestions?

void insertfav_av(favnode*list, aeronava *av){         favnode* nn = (favnode*)malloc(sizeof(favnode));         //first = list;         nn->infoutil = (aeronava*)malloc(sizeof(aeronava));         nn->infoutil->idaeronava = (char*)malloc(strlen(av->idaeronava) + 1);         //strcpy(nn->infoutil->idaeronava, av->idaeronava);         nn->infoutil = av;         if (first == null){             nn->prev = nn->next = nn;             first = nn;         }         else{             list = first;             while (list->next != first){                 list = list->next;             }             nn->prev = list;             list->next = nn;             nn->next = first;          } }   struct aeronava{     char* idaeronava;     tipa tipaero;     short int nrlocuri;     double greutatemaxima; };  struct favnode{     favnode*next;     favnode*prev;     aeronava* infoutil; }; 

        nn->prev = list;   // 1         list->next = nn;   // 2         nn->next = first;  // 3 

lines 1 , 2 link nn list in both directions, line 3 links nn first in 1 direction only. lack opposite link update here:

        first->prev = nn;