socket programming - some warning when compilation

This is a discussion on socket programming - some warning when compilation within the Linux Programming forums, part of the Platform Specific Boards category; Im studying an example about text exchange between client server in UDP socket Using gcc -Wall -o server server.c Some ...

  1. #1
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    socket programming - some warning when compilation

    Im studying an example about text exchange between client server in UDP socket
    Using gcc -Wall -o server server.c
    Some warning appear.I dont know the meaning and how to fix it.Thanks in advance!

    server.c:73:8: warning: comparison between pointer and integer [enabled by default]
    server.c:131:58: warning: pointer targets in passing argument 6 of ‘recvfrom’ differ in signedness [-Wpointer-sign]
    /usr/include/i386-linux-gnu/sys/socket.h:166:16: note: expected ‘socklen_t * __restrict__’ but argument is of type ‘int *’
    server.c:142:57: warning: pointer targets in passing argument 6 of ‘recvfrom’ differ in signedness [-Wpointer-sign]
    /usr/include/i386-linux-gnu/sys/socket.h:166:16: note: expected ‘socklen_t * __restrict__’ but argument is of type ‘int *’




    Code:
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <string.h>
    #include <stdlib.h>
    #include <stdio.h>
     
    int main(int argc,char* argv[])
    {
    //---------------- tao cac struct ban tin----------
     struct hello {
    char hello_id[11];//10 ky tu dientu-k53 + 1 ki tu ket thuc
    long int hello_len; //32bit
    long int hello_detect;
    char mail_user[50];    //mail user from client
    } HEL;
    HEL.hello_detect=0;
     
    struct acknowledgement {
    char ack_id[11];
    long int ack_len;
     
    long int ack_detect;
    char client_mail[50];    //tra ve mail user cho client
    char ack_state[20];     //trang thai "success" or "failed"
    } ACK;
    strcpy(ACK.ack_id,"dientu-K53");
    ACK.ack_detect=1;
    //char ack_state[];        //vua thay doi
     
    struct bye {
    char bye_id[11];
    long int bye_detect;
    } BYE;
    strcpy(BYE.bye_id,"dientu-K53");
    BYE.bye_detect=2;
     
    int dem=0;
     
    //----------ket thuc tao ban tin -----------------
     
    int serverSocket;
    serverSocket=socket(PF_INET,SOCK_DGRAM,0);
    if(serverSocket==-1)
    {
    perror("UDP server socket !!! \n");
    close(serverSocket);
    exit(1);
    }
     
    int i=1;  //option for enabling reuse option below
    int check;
    /*check=setsockopt(serverSocket,SOL_SOCKET,SO_REUSEADDR,&i,sizeof(int));
    if(check=-1)
    {
    perror("failed to set reuse\n");
         
    }    */
    //---------loading socket address structure------------
    struct sockaddr_in serverAddress;
    //struct sockaddr_in clientAddress;
    serverAddress.sin_family=AF_INET;
    serverAddress.sin_port=htons(5011);
    serverAddress.sin_addr.s_addr=INADDR_ANY;
    //socklen_t len=sizeof (struct sockaddr_in);
    //-------------------define length of clientaddr , serveraddr--------------------
    //int clientaddrlen=sizeof(clientAddress);
    int serveraddrlen=sizeof(serverAddress);
     
    check=bind(serverSocket,(struct sockaddr *)&serverAddress,serveraddrlen);
    if(bind==-1)
    {
    perror("failed to bind socket address structure\n");
    close(serverSocket);
    exit(0);
    }         //gia tri tra ve cua bind trong UDP connectionless la con tro        
     
    else {//--------------DATA handling begin ----------------------
    printf("chuan bi xu ly \n");
    //------------------------Declare prototypes-------------------------
    //struct sockaddr_in clientAddress;
    //len=sizeof(struct sockaddr_in);
    fd_set readfds;        //check sockets ready for reading
    fd_set masterfds;     //luu thay doi cua readfds
    FD_ZERO(&readfds);
    FD_ZERO(&masterfds);
    FD_SET(serverSocket,&masterfds);    //add udp serverSocket vao array masterfds
    int max_fd=serverSocket;     //=3
    struct timeval timeout;        //timeout cho select()
    timeout.tv_sec=90;
    timeout.tv_usec=0;
    int n_select;
    int close_fd=0;        //khai bao kiem tra fd state
    do  { //-----endless loop---------------
    memcpy(&readfds,&masterfds,sizeof(masterfds));  //load masterfds to readfds
    printf("chuan bi select \n");
    n_select=select(max_fd+1,&readfds,NULL,NULL,NULL);
    printf("da thuc hien ham select \n");
    if (n_select < 0)
            {
                    perror("SELECT");
                    exit(0);
            }
            else
            if (n_select == 0)
            {
                printf("Time out\n");
            }
            else
            {    
                i=serverSocket;
                 // for (i = 0; i <= max_fd;i++)    //duyet cac file descriptors
                   //{
                        if (FD_ISSET(i,&readfds))//neu co file descriptor"ready to read"
                        {
                            //int close_fd = 0;    //kiem tra socket co nen duoc dong sau khi xu ly hay ko?
                struct sockaddr_in clientAddress;
                int clientaddrlen=sizeof(clientAddress);
                    //gan i =serverSocket    
     
    //-----------------------Data processing---------------------------------------
                 printf("receive HELLO+send ACK bulletin\n");
                    printf("Receive data in socket %d\n",i);
                                int nrecv ;
                //nhan mail tu remote client 
                        char mail_temp[100][50];        //danh sach tam
                     
                dem++;    //thao tac tren mail list dau tien
                nrecv=recvfrom(i,mail_temp[dem],50,0,(struct sockaddr*)&clientAddress,&clientaddrlen);        //hello_mail
                    if(nrecv==-1)
                    {
                    printf("In socket-received mail %d\n",i);
                    perror("RECEIVE");
                    close_fd=1;   
                    }// end if nrecv_mail
                 
            //hien thi chuoi
            printf("mail user tu client gui la: %s\n",mail_temp[dem]);     
    //-------------------------------------------------------
                nrecv= recvfrom(i,HEL.hello_id,11,0,(struct sockaddr*)&clientAddress,&clientaddrlen);    //PROBLEM HERE-chua gan default cho hello_id o client
                                if (nrecv == -1)
                                {
                                    printf("In socket-receive ID %d\n",i);
                                    perror("RECEIVE");
                                    close_fd = 1;    //co loi nao close_fd=1 de dong socket
                                }
                               // else
                               // {
            printf("Hello_id received=%s.\n",HEL.hello_id);
                     
     
                    if(strcmp(HEL.hello_id,"dientu-K53")==0)    //hello_id :dung-> tra ve 0
                    {
                    printf("ban tin hop le \n");
                    goto moveon;
                    }
                     
                    else
                    {
                    printf("ban tin khong hop le\n");
                    exit(0);
                    }
             
                         
             
                     
         
                             
            //nhan gia tri hello_len
    moveon:                nrecv=recvfrom(i,&HEL.hello_len,4,0,(struct sockaddr*)&clientAddress,&clientaddrlen);
                    if(nrecv==-1)
                    {
                    printf("In socket-received length: %d \n",i);
                    perror("RECEIVE");
                    //close_fd=1;
                    }//end if nrecv_len
            //nhan gia tri hello_detect
                    nrecv=recvfrom(i,&HEL.hello_detect,4,0,(struct sockaddr*)&clientAddress,&clientaddrlen);
                     
                    if(nrecv==-1)
                    {
                    printf("In socket-received detect: %d \n",i);
                    perror("RECEIVE");
                    close_fd=1;    //dong socket 
                    }
             
            //Save email user vao mang 2 chieu
            char list_mail [100][50];
            //mang 1 chieu 100 phan tu, moi phan tu 50 ki tu-> giong danh sach
                   // int count=0;
    In_mail:        strcpy(list_mail[dem],mail_temp[dem]);
                    //cong luon
                    printf("mail vua update vao list la: %s \n",list_mail[dem]);
                int j=1;
                printf("------------------Hien thi danh sach email:---------------\n");
                for(j=1;j<=dem;j++)
                {
                printf(" mail thu %d : %s \n ",j,list_mail[j]);
                }
                printf("-------------------End my list----------------------");    
            //gan gia tri cho truong trang thai ACK.ack_state
                 
                    if(strcmp(list_mail[dem],mail_temp[dem])==0)    //dung->return 0
                    {
                    printf("luu email thanh cong \n");
                    strcpy(ACK.ack_state,"success");
                    printf("ack vua gan la %s \n",ACK.ack_state);
                    }
                    else
                    {
                    printf("luu email that bai \n");
                    strcpy(ACK.ack_state,"failed");
                    }
                    //ACK length calculation
            //HEL.hello_len=strlen(HEL.hello_id)+strlen(HEL.mail_user)+sizeof(HEL.hello_detect);
            ACK.ack_len=strlen(ACK.ack_id)+sizeof(ACK.ack_detect)+strlen(ACK.client_mail)+strlen(ACK.ack_state)+4;
                    //feedback lai client ban tin ack:
     
                    int nsent;
                    nsent=sendto(i,ACK.ack_id,11,0,(struct sockaddr*)&clientAddress,clientaddrlen);        //ack_id
                    if(nsent==-1)
                    {           printf("In socket-error when sending ack ID %d\n",i);
                                                perror("SEND");
                                                close_fd = 1;
                                    }
                 
                    nsent=sendto(i,&ACK.ack_len,4,0,(struct sockaddr*)&clientAddress,clientaddrlen);        //ack_len
                     
                    if(nsent==-1)
                    {           printf("In socket-error when sending ack len %d\n",i);
                                                perror("SEND");
                                                close_fd = 1;
                                    }
                    nsent=sendto(i,&ACK.ack_detect,4,0,(struct sockaddr*)&clientAddress,clientaddrlen);    //ack_detect
     
                    if(nsent==-1)
                    {           printf("In socket-error when sending ack detect %d\n",i);
                                                perror("SEND");
                                                close_fd = 1;
                                    }
     
                    strcpy(ACK.client_mail,mail_temp[dem]);    //ack_mail  -< error
                     
     
                    nsent=sendto(i,ACK.client_mail,50,0,(struct sockaddr*)&clientAddress,clientaddrlen);
                    if(nsent==-1)
                    {           printf("In socket-error when sending back CLIENT MAIL %d\n",i);
                                                perror("SEND");
                                                close_fd = 1;
                                    }
                    printf("state chuan bi gui di la : %s \n",ACK.ack_state);
                    nsent=sendto(i,ACK.ack_state,20,0,(struct sockaddr*)&clientAddress,clientaddrlen);    //ack_state
                    if(nsent==-1)
                    {           printf("In socket-error when sending ack_state %d\n",i);
                                                perror("SEND");
                                                close_fd = 1;
                                    }
                    printf("state vua gui di la : %s \n",ACK.ack_state);
     
                    printf("successfully sent ACK bulletin to client\n");
                    //goto Round_Check;
                        //int nsent = send(i,message2,strlen(message2),0);
                    //end feedback
     
                                       /* else
                                        {
                                            close_fd = 1;
                                        }*/
     
                printf("receive BYE bulletin \n");        //PROBLEM HERE?
                nrecv=recvfrom(i,BYE.bye_id,11,0,(struct sockaddr*)&clientAddress,&clientaddrlen);        //bye_id
                if(nrecv==-1)
                {
                printf("received bye_id bulletin failed\n");
                perror("RECEIVE");
                exit(0);
                }
                nrecv=recvfrom(i,&BYE.bye_detect,4,0,(struct sockaddr*)&clientAddress,&clientaddrlen);        //bye_detect
                if(nrecv==-1)
                {
                printf("received bye_id bulletin failed\n");
                perror("RECEIVE");
                exit(0);
                }
                close_fd=1;
                printf("remote client closed its socket\n");
                 
                goto close_socket;     //thoat khoi checking FD_ISSET
     
    //-----------------------End of data processing--------------------------------        
     
      
                }//end if of FD_ISSET
            //}//end for
            }//end of else
        }//end do while
    while(1);
     
     
     
     
     
     
     
    }// ------------------end esle of DATA handling--------------------
        //close(close_fd);
    close_socket: close(serverSocket);
     
    exit(0);
     
     
    }//end main

  2. #2
    Registered User
    Join Date
    Oct 2006
    Posts
    2,391
    it's telling you exactly what you need to do. it's expecting a socklen_t* and you're giving it an int*. try changing the type of your size variables to socklen_t or unsigned int, and that should fix most of your problems.

  3. #3
    Registered User
    Join Date
    May 2012
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    2
    Quote Originally Posted by Elkvis View Post
    it's telling you exactly what you need to do. it's expecting a socklen_t* and you're giving it an int*. try changing the type of your size variables to socklen_t or unsigned int, and that should fix most of your problems.
    Thanks for ur advice.I 've recently fixed it after seeing an article from the internet.It's exactly what u say .But the server seems to work well withou fixing the problem( i does not affect the system,i think so)

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