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POHaving issues with chat program over TCP using C++ on Ubuntu 12.10
 

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  1. POHaving issues with chat program over TCP using C++ on Ubuntu 12.10
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    <p>I'm developing a chat program over TCP to allow me to communicate between two machines over WAN. I'm pretty new to C++ (coming from Java) and am very new to TCP, so don't go too hard on me! (: I've looked around on a fair amount of tutorials and continue to find only Echo programs, nothing that can leave a connection open for an extended amount of time to allow a chat like function. My current code looks like this: </p> <pre><code>#include "ClientManager.h" ClientManager::ClientManager() { } void ClientManager::connectCom(char* ipAdd) { portno = atoi(PORT); sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd &lt; 0) error("ERROR opening socket"); server = gethostbyname(ipAdd); if (server == NULL) { fprintf(stderr,"ERROR, no such host\n"); exit(0); } bzero((char *) &amp;serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; bcopy((char *)server-&gt;h_addr, (char *)&amp;serv_addr.sin_addr.s_addr, server-&gt;h_length); serv_addr.sin_port = htons(portno); if (connect(sockfd,(struct sockaddr *) &amp;serv_addr,sizeof(serv_addr)) &lt; 0) error("ERROR connecting"); } void ClientManager::message(std::string msg) { // printf("Please enter the message: "); char * buffer = new char[msg.size() + 1]; std::copy(msg.begin(), msg.end(), buffer); buffer[msg.size()] = '\0'; // bzero(buffer,256); // fgets(buffer,255,stdin); n = write(sockfd,buffer,strlen(buffer)); if (n &lt; 0) error("ERROR writing to socket"); bzero(buffer,256); n = read(sockfd,buffer,255); if (n &lt; 0) error("ERROR reading from socket"); printf("%s\n",buffer); bzero(buffer,256); } void ClientManager::closeCom() { close(sockfd); } void ClientManager::error(const char *msg) { perror(msg); exit(0); } </code></pre> <p>and my server manager looks like this: </p> <pre><code>#include "ServerManager.h" ServerManager::ServerManager() { // int sockfd, portno, n; // struct sockaddr_in serv_addr; // struct hostent *server; } void ServerManager::openCom() { char buffer[256]; struct sockaddr_in serv_addr, cli_addr; int n; socklen_t clilen; sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd &lt; 0) error("ERROR opening socket"); bzero((char *) &amp;serv_addr, sizeof(serv_addr)); portno = atoi(PORT); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = INADDR_ANY; serv_addr.sin_port = htons(portno); if (bind(sockfd, (struct sockaddr *) &amp;serv_addr, sizeof(serv_addr)) &lt; 0) error("ERROR on binding"); listen(sockfd,5); clilen = sizeof(cli_addr); newsockfd = accept(sockfd, (struct sockaddr *) &amp;cli_addr, &amp;clilen); if (newsockfd &lt; 0) error("ERROR on accept"); bzero(buffer,256); // n = read(newsockfd,buffer,255); // if (n &lt; 0) error("ERROR reading from socket"); // printf("Here is the message: %s\n",buffer); // n = write(newsockfd,"I got your message",18); // if (n &lt; 0) error("ERROR writing to socket"); } int ServerManager::readCom() { bzero(buffer,256); n = read(newsockfd,buffer,255); if (n &lt; 0) error("ERROR reading from socket"); printf("Here is the message: %s\n",buffer); n = write(newsockfd,"I got your message",18); if (n &lt; 0) error("ERROR writing to socket"); if (buffer[0] == '0') return 1; return 0; } void ServerManager::closeCom() { close(newsockfd); close(sockfd); } void ServerManager::error(const char *msg) { perror(msg); exit(1); } </code></pre> <p>Both of these classes are implemented by separate main functions who call the functions necessary. I know that the code itself is ok for sending a single message- its been doing that for awhile now. Its just when client calls more than one message() that I experience errors, specifically, a segmentation fault. This only happens on the second message, the first one is sent and received appropriately.</p> <p>If anyone could help me out, it would be greatly appreciated. Thanks!</p>
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      1. POHaving issues with chat program over TCP using C++ on Ubuntu 12.10
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    1. COWhat is the stack when the segfault occurs? You can run the program in gdb and use `where` to get the stack when it crashes. See http://www.cs.rochester.edu/~nelson/courses/csc_173/review/gdb.html.
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    2. COHere is the output of GDB. Is this what you mean? `#0 0xb7e0f884 in __nss_hostname_digits_dots () from /lib/i386-linux-gnu/libc.so.6 #1 0xb7e143fd in gethostbyname () from /lib/i386-linux-gnu/libc.so.6 #2 0x08048e62 in ClientManager::connectCom(char*) () #3 0x08048c82 in main (argc=1, argv=0xbffff354) at client.cpp:20 `
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      1. POHaving issues with chat program over TCP using C++ on Ubuntu 12.10
      1. USjmarple
 

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