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POGuide me with sockets: server-client program that multiplies 2x2-arrays
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I'm trying to write a c code with sockets to communicate a server and a client (or parent and child, as you prefer) but I'm really noob at this and I only keep getting errors. I know there are lots of mistakes in my code, but right now I keep getting a "segmentation fault" error. I know that the elements doesn't point each other but it's too late in my country and this all seems like a foreign language to me. I would really appreciate any help that you could offer me. That's all, thanks in advance. SERVER.c CODE------------------------------------------------------------------------------------------------- <pre><code>//#include <sys/un.h> //per utilitzar sockaddr_un #include <string.h> #include <sys/types.h> #include <sys/socket.h> //per utilitzar sockaddr #include <unistd.h> #define FEMISSOR "multi.socket" // per enviar dades a l'emissor ???????? int main(int argc, char *argv[]){ //si es volen utilitzar paràmetres int s; //el socket int n; int i, j; char c, num_fill[6]; struct sockaddr s_struct; //l'estructura del socket unsigned int v; //per guardar el tamany de s_struct char msg[50]; //buffer dels missatges int a11, a12, a21, a22, b11, b12, b21, b22; int a, b, x, d; //Las variables que guardan los valores de las matrices. //Introduccion de los valores de la Matriz 1 printf ("Introduce la primera matriz en orden a11 a12 a21 a22:\n"); scanf ("%d %d %d %d", &a11, &a12, &a21, &a22); //Introduccion de los valores de la Matriz 2 printf ("Introduce la segunda matriz en orden b11 b12 b21 b22:\n"); scanf ("%d %d %d %d", &b11, &b12, &b21, &b22); printf ("Los valores de las matrices son: %d %d %d %d; %d %d %d %d\n", a11, a12, a21, a22, b11, b12, b21, b22); //Realizar la introducción de las matrices for (i=0;i<4;i++){ printf ("Entra en el for de FORKS\n"); sprintf(num_fill, "Fill%d", i); if (fork()==0){ //es pot crear un procés fill i executar ./receptor printf ("Entra en el fork %d\n", i); execl("./fill", "fill", num_fill, NULL); exit(0);} printf ("Imprimeix nom: %s\n", num_fill); } printf("Emissor. Esperant uns segons a que el receptor hagi creat el seu socket\n"); sleep(1); // ho ha de fer el primer que s'executa per esperar l'altre, de 1s a Xs if ((s=socket(AF_UNIX, SOCK_DGRAM,0)) <0){ //crea el socket perror ("Emissor. Error socket:"); exit(1); } s_struct.sa_family=AF_UNIX; strcpy(s_struct.sa_data, FEMISSOR); //Emisor if (bind (s, &s_struct, sizeof(s_struct))<0){ //associa un nom de fitxer al socket perror ("Emissor. Error associant:"); //qui reb és qui ha de fer el bind close(s); exit(2); } for (i=0; i<4; i++){ switch (i) { case 0: a=a11 ; b=a12 ; x=b11 ; d=b21; break; case 1: a=a11 ; b=a12 ; x=b12 ; d=b22; break; case 2: a=a21 ; b=a22 ; x=b11 ; d=b21; break; case 3: a=a21 ; b=a22 ; x=b12 ; d=b22; break; } s_struct.sa_family=AF_UNIX; sprintf (num_fill, "Fill%d", i); strcpy(s_struct.sa_data, num_fill); //envia al fitxer socket del receptor v= sizeof(s_struct); sprintf(msg, "%d %d %d %d", a, b, x, d); printf("Multi. Enviant dades a %s", s_struct.sa_data ); if((n=sendto(s, msg, strlen(msg)+1, 0, &s_struct, sizeof(s_struct)))<0) { perror ("Multi. Error enviant:\n"); unlink(num_fill); //Al receptor: FRECEPTOR close (s); exit(3); } printf("Emissor. %d dades enviades: %s\n", n, msg); } // for para recibir los datos de los hijos for (i=0; i<4; i++){ s_struct.sa_family=AF_UNIX; strcpy(s_struct.sa_data, FEMISSOR); //envia al fitxer socket del receptor if((n=(recvfrom(s, &msg, sizeof(msg), 0, &s_struct, &v)))<0) { perror ("Multi. Error rebent:"); unlink(FEMISSOR); //Al receptor: FRECEPTOR close (s); exit(3); //Al receptor: n=(recvfrom(s, &msg, sizeof(msg), 0, &s_struct, &v)) } if ( strncmp(s_struct.sa_data,"Fill0",5)==0){ sscanf(msg,"%d", &a);} if ( strncmp(s_struct.sa_data,"Fill1",5)==0){ sscanf(msg,"%d", &b);} if ( strncmp(s_struct.sa_data,"Fill2",5)==0){ sscanf(msg,"%d", &x);} if ( strncmp(s_struct.sa_data,"Fill3",5)==0){ sscanf(msg,"%d", &d);} } printf("Datos recibidos de %s\n", s_struct.sa_data); printf("Resultado de la multiplicacion:\n"); printf("Matriu 1: %d %d\n %10d %d\n", a11, a12, a21, a22); printf("Matriu 2: %d %d\n %10d %d\n", b11, b12, b21, b22); printf("Matriu R: %d %d\n %10d %d\n\n", a, b, x, d); printf("Emissor. Prem una tecla per acabar i eliminar el socket\n"); // for para imprimir las matrices. scanf("%c",&c); unlink(FEMISSOR); //es tanca el fitxer que s'ha obert al bind close(s); } </code></pre> <hr> CLIENT.c CODE <pre><code>//#include <sys/un.h> //per utilitzar sockaddr_un #include <string.h> #include <sys/types.h> #include <sys/socket.h> //per utilitzar sockaddr #include <unistd.h> //s'utilitzen dos fitxers, un pel socket de cada procés. Cada procés fa el bind del seu //Al sendto y al recvfrom es posa al camp sa_data el fitxer a qui es fa la petició. #define FEMISSOR "multi.socket" // per enviar dades a l'emissor #define Fill0 "f0.socket" // per enviar dades al receptor (si és bidireccional) <---- i think those lines are not supposed to exist XD #define Fill1 "f1.socket" #define Fill2 "f2.socket" #define Fill3 "f3.socket" int main(int argc, char *argv[1]){ //si es volen utilitzar paràmetres int s; //el socket int n; char c, num_fill[6]; struct sockaddr s_struct; //l'estructura del socket unsigned int v; //per guardar el tamany de s_struct char msg[50]; //buffer dels missatges int a1, a2, b1, b2; //Las variables para ingresar los numeros. int resultado; strcpy (num_fill, argv[1]); printf ("Creat %s\n", num_fill); if ((s=socket(AF_UNIX, SOCK_DGRAM,0))<0){//crea el socket perror ("Fill. Error socket:"); exit(1); } s_struct.sa_family=AF_UNIX; strcpy(s_struct.sa_data, num_fill); //El receptor utilitzarà el nom FRECEPTOR i f (bind (s, &s_struct, sizeof(s_struct))<0){ //associa un nom de fitxer al socket perror ("Fill. Error associant:"); //qui reb és qui ha de fer el bind close(s); exit(2); } s_struct.sa_family=AF_UNIX; strcpy(s_struct.sa_data, num_fill); //Recibe los datos del receptor if((n=(recvfrom(s, &msg, sizeof(msg), 0, &s_struct, &v)))<0) { perror ("Receptor. Error enviant:"); unlink(num_fill); //Al receptor: FRECEPTOR close (s); exit(3); //Al receptor: n=(recvfrom(s, &msg, sizeof(msg), 0, &s_struct, &v)) } printf("Datos recibidos en %s\n", num_fill); sscanf(msg,"%d %d %d %d",&a1,&a2,&b1,&b2); resultado = (a1*b1)+(a2*b2); printf ("El resultado de %s es: %d\n", num_fill, (int) resultado); s_struct.sa_family=AF_UNIX; s trcpy(s_struct.sa_data, num_fill); //envia al fitxer socket del receptor v= sizeof(s_struct); sprintf(msg, "%d", resultado); printf("Fill. Enviant resultat a %s\n", s_struct.sa_data ); if((n=sendto(s, msg, strlen(msg)+1, 0, &s_struct, sizeof(s_struct)))<0) { perror ("Emissor. Error enviant:"); unlink(num_fill); //Al receptor: FRECEPTOR close (s); exit(3); } printf("%s. %d dades enviades: %s\n", num_fill, n, msg); unlink(num_fill); //es tanca el fitxer que s'ha obert al bind close(s); } </code></pre> <hr> PS: The code is supposed to be multipliying two 2x2 arrays. The parent creates a socket to communicate with the child. There must be 5 processes: The parent creates 4 child processes that multiply one row for one column to get the 4 resultant integers. Child processes will be parallel-executed. Main process creates a socket to communicate with childs that will then be created, codified into an external program. It also passes an arguments that is the # of the child. Childs create their own socket. Each one will use a different file for the linkage (fitxerf1, fitxerf2....fitxerf4). The parent waits 1 second for its child to create the sockets. Once the link has been created, the parent passes each child 4 int values using each file. Each child will return to the parent's communication file the solution of each multiplication. Eventually, the parent shows what it's receiving from each child and the three arrays (the first ones and the result)
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<c><sockets><client><communication>
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Guide me with sockets: server-client program that multiplies 2x2-arrays
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