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POSimple network-programming program - not working
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4369731
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4369789
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2010-12-06T18:35:58.403
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2010-12-06T20:33:30.157
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I just began learning network programming. My first program is very simple: once connected, the server program displays what the client program sends (characters). Everything works fine until they get connected. At first, I did the sending loop using putc: <pre><code>while((c = getc(stdin)) != '\n') putc(c, (FILE *) connection); </code></pre> and the receiving one with getc: <pre><code>while((c = getc((FILE *) connection)) != '\n') putc(c, stdout); </code></pre> Once connected, I get a segmentation fault. Then I tried using send: <pre><code>while(1) { memset(str, null, strlen(memset)); while(((c = getc(stdin)) != '\n') && sizeof(str) <= 100) { strcat(str, (char *) c); // cast to char * is to make gcc happy } send(connection, (void *) str, sizeof(str), (int) NULL); } </code></pre> and recv: <pre><code>while((stat = recv(connection,str,100,0)) != 0) { printf("\nReceived %d bytes of data from %s: %s", stat, client, str); } </code></pre> Now recv() keeps returning -1 and errno is set to 107. What does this mean? Where am I doing wrong? By the way I'm using Linux with gcc. Thanks a lot for your help! :) <hr> EDIT: Even if I used getc() and putc(), I get connection with socket(), then I connect() (client). The server, after obtaining connection (with socket()) bind()s, then listen()s and accept()s. Sorry if I ometted. <hr> Here's the server code: <pre><code>#include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <errno.h> #include <arpa/inet.h> #include <netdb.h> void main(int argc, char *argv[]) { struct addrinfo hint; struct addrinfo *servinfo, *count; struct sockaddr_storage conn_addr; struct sockaddr host; int connessione; int stat; int conn_sock; int conn_size; int success; int c; char t[INET_ADDRSTRLEN]; char str[100]; char *client; if(argc != 1 && strcmp(argv[1], "aiuto") == 0) { printf("%s(porta)\n",argv[0]); printf("porta: specifica su quale porta installarsi\n"); exit(-1); } memset(&hint,0,sizeof hint); hint.ai_family = AF_INET; hint.ai_socktype = SOCK_STREAM; hint.ai_flags = AI_PASSIVE; if((stat = getaddrinfo(NULL, argv[1], &hint, &servinfo)) != 0) { printf("\n[FATAL]: getaddrinfo: %s",gai_strerror(stat)); exit(-1); } success = 0; for(count = servinfo; count != NULL; count = count->ai_next) { if((connessione = socket(count->ai_family, count->ai_socktype, count->ai_protocol)) <= 0) continue; if((stat = bind(connessione, count->ai_addr, count->ai_addrlen)) == 0) { success = 1; break; } else { continue; } } if(success == 0) { printf("\n[FATAL]: Unable to bind()!\n"); exit(-1); } else { printf("\n[DEBUG]: %s: listening...", argv[0]); } servinfo = count; freeaddrinfo(count); if(listen(connessione, 20) == -1) { printf("\n[FATAL]: listen: %s (%d)\n", gai_strerror(errno), errno); close(connessione); exit(-1); } conn_size = sizeof(conn_addr); if(accept(connessione, (struct sockaddr *) &conn_addr, &conn_size) == -1) { printf("\n[FATAL]: accept: %s", gai_strerror(errno)); close(connessione); exit(-1); } client = (char *) malloc(INET_ADDRSTRLEN * sizeof(char)); client = inet_ntop(servinfo->ai_family, &conn_addr, t, INET_ADDRSTRLEN); printf("\n[DEBUG]: %s: connection accepted: %s", argv[0], client); while((stat = recv(connessione,str,100,0)) != 0) { printf("\nReceived %d bytes of data from %s: %s", stat,client, str); } printf("\n[DEBUG]: connection closed by %s\n",client); } </code></pre> And the client's code: <pre><code>#include <stdio.h> #include <string.h> #include <stdlib.h> #include <assert.h> #include <sys/types.h> #include <sys/socket.h> #include <errno.h> #include <arpa/inet.h> #include <netdb.h> void main(int argc, char *argv[]) { struct addrinfo hint; struct addrinfo *servinfo, *count; struct sockaddr_storage conn_addr; struct sockaddr host; int connessione; int stat; int conn_sock; int conn_size; int success; int c; char t[INET_ADDRSTRLEN]; char *indirizzo; char str[100]; memset(&hint,0,sizeof hint); host.sa_family = AF_INET; if(inet_pton(host.sa_family, argv[1], (void *) host.sa_data) == -1) { printf("\n[FATAL]: pton: %s (%d)\n", gai_strerror(errno), errno); exit(-1); } hint.ai_family = AF_INET; hint.ai_socktype = SOCK_STREAM; hint.ai_flags = AI_PASSIVE; hint.ai_addr = &host; if((stat = getaddrinfo(argv[1], argv[2], &hint, &servinfo)) != 0) { printf("[FATAL]: getaddrinfo: %s\n",gai_strerror(stat)); exit(-1); } success = 0; for(count = servinfo; count != NULL; count = count->ai_next) { if((connessione = socket(count->ai_family, count->ai_socktype, count->ai_protocol)) == -1) continue; if(connect(connessione, count->ai_addr, count->ai_addrlen) != -1) { success = 1; break; } } if(success == 0) { printf("\n[FATAL]: impossibile trovare l'host specificato\n"); exit(-1); } servinfo = count; freeaddrinfo(count); indirizzo = (char *) malloc(INET_ADDRSTRLEN * sizeof(char)); indirizzo = inet_ntop(servinfo->ai_family, &conn_addr, t, INET_ADDRSTRLEN); printf("\n[DEBUG]: %s: connesso a: %s\n",argv[0], indirizzo); while(1) { strcpy(str,"buffer for data to send"); while(((c = getc(stdin)) != '\n') && sizeof(str) <= 100) { strcat(str, (char *) c); } send(connessione, (void *) str, sizeof(str), (int) NULL); } } </code></pre> <hr> At the end... It works perfectly! Thanks everyone. :)
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<c++><c><linux><gcc><network-programming>
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Simple network-programming program - not working
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