Question

我目前正在研究服务器 - 客户端对，它会在发送到服务器时拼写检查txt文件，但我的代码只是在中途挂起。希望有不同观点的人可以告诉我我没有看到的东西。这是服务器代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main(int argc, char *argv[]){
  int welcomeSocket, newSocket;
  char *dictionary[100000];
  char buffer[1024];
  struct sockaddr_in serverAddr;
  struct sockaddr_storage serverStorage;
  socklen_t addr_size;

//create socket. 0 means TCP
welcomeSocket = socket(PF_INET, SOCK_STREAM, 0);
//address family -> internet
serverAddr.sin_family = AF_INET;
//set port number using htons for byte ordering
serverAddr.sin_port = htons(19703);
//set IP to localhost
serverAddr.sin_addr.s_addr=htonl(INADDR_ANY); //any IP
//set bits of the padding field to 0
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
//bind address to the socket
bind(welcomeSocket, (struct sockaddr *) &serverAddr, sizeof(serverAddr));
//listen on socket 19703, max 5 connections queued
if(listen(welcomeSocket,5) == 0)
  printf("Listening...\n");
else
  printf("Error\n");

//copy dictionary to array
  FILE *fp;
  char temp[100];
  fp = fopen(argv[1], "r");
  int pos = 0;
  while(fgets(temp, 1024, fp) != NULL){
      strtok(temp, "\n");     //remove trailing newline
      dictionary[pos] = temp;
      pos++;
  }

//accept creates a new socket for the incoming connection
addr_size = sizeof serverStorage;
newSocket = accept(welcomeSocket, (struct sockaddr *) &serverStorage, &addr_size);
printf("accepted...\n");

//receive word from client
  read(newSocket, buffer, 1024);
printf("read...\n");
//spit it back out (used in testing and debugging
  printf("The word is: %s", buffer);

//search dictionary array
  int i=0;
  int good=0;
  while(dictionary[i] != NULL){
    if(strcmp(buffer, dictionary[i])==0){
      printf("%s - OK\n", buffer);
      good++;
      i++;
    }
  }
if(good == 0){
  printf("%s - MISSPELLED\n", buffer);
}
  return 0;
}//end main

正如您所看到的，我有一些用于调试的printf语句。为了告诉你它挂起的地方（奇怪的地方）我在客户端发送时得到的输出是：

Listening...
accepted...
read...

我无法说明为什么会这样。感谢任何能够解决问题的人。我正在为这个工作做更多的工作，因为我仍然需要实现多线程和信号量和东西。

Answer 1

以下提议的代码：

更正了评论中列出的问题
执行所需的功能
干净地编译
尚未经过测试
正确检查错误
将其留给OP，以便在每次调用exit()

现在建议的代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>   // socket()
#include <netinet/in.h>
#include <string.h>

#define MAX_DICTIONARY_ENTRIES 100000
#define MAX_BUFFER_LEN         1024
#define MAX_TEMP_BUF           100


int main( int argc, char *argv[] )
{
    int welcomeSocket;
    int newSocket;

    char *dictionary[ MAX_DICTIONARY_ENTRIES ] = {NULL};
    char buffer[ MAX_BUFFER_LEN +1]; // plus 1 to allow for NUL terminator byte

    struct sockaddr_in serverAddr;
    struct sockaddr_storage serverStorage;
    socklen_t addr_size;

    if( 2 != argc )
    {
        fprintf( stderr, "USAGE: %s <dictionaryFileName>\n", argv[0] );
        exit( EXIT_FAILURE );
    }

    // implied else, correct number of arguments

    //create socket. 0 means TCP
    welcomeSocket = socket(PF_INET, SOCK_STREAM, 0);
    if( 0 > welcomeSocket )
    {
        perror( "socket failed" );
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, socket successful

    //address family -> internet
    serverAddr.sin_family = AF_INET;

    //set port number using htons for byte ordering
    serverAddr.sin_port = htons(19703);

    //set IP to localhost
    serverAddr.sin_addr.s_addr=htonl(INADDR_ANY); //any IP

    //set bits of the padding field to 0
    memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);

    //bind address to the socket
    if( 0 != bind( welcomeSocket, (struct sockaddr *) &serverAddr, sizeof(serverAddr) ) )
    {
        perror( "bind failed" );
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, bind successful

    //listen on socket 19703, max 5 connections queued
    if( listen( welcomeSocket, 5 ) != 0 )
    {
        perror( "listen failed" );
        printf("Error\n");
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, listen successful

    printf( "listening...\n" );

    //copy dictionary to array
    FILE *fp;
    char temp[ MAX_TEMP_BUF ];
    fp = fopen(argv[1], "r");
    if( !fp )
    {
        perror( "fopen failed" );
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    size_t pos = 0;
    while( pos < (sizeof dictionary / sizeof dictionary[0])
        && fgets( temp, sizeof temp, fp ) )
    {
        strtok(temp, "\n");     //remove trailing newline
        dictionary[pos] = strdup(temp);
        if( !dictionary[pos] )
        {
            perror( "strdup failed" );
            // TODO: cleanup
            exit( EXIT_FAILURE );
        }

        // implied else, strdup successful

        pos++;
    }

    fclose( fp );

    //accept creates a new socket for the incoming connection
    addr_size = sizeof serverStorage;
    newSocket = accept(welcomeSocket, (struct sockaddr *) &serverStorage, &addr_size);
    if( 0<= newSocket )
    {
        perror( "accept failed" );
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, accept successful

    printf("accepted...\n");

    //receive word from client
    ssize_t bytesread = read(newSocket, buffer, sizeof buffer);
    if( 0 >= bytesread )
    {
        perror( "read failed" );
        // TODO: cleanup
        exit( EXIT_FAILURE );
    }

    // implied else, read successful

    buffer[bytesread] = '\0';  // terminate the string
    printf("read...\n");

    //spit it back out (used in testing and debugging
    printf("The word is: %s\n", buffer);

    //search dictionary array
    int good=0;
    for( size_t i=0; dictionary[i] != NULL; i++)
    {
        if(strcmp(buffer, dictionary[i])==0)
        {
            printf("%s - OK\n", buffer);
            good++;
            break; // exit 'for()' loop
        }
    }

    if( !good )
    {
        printf("%s - not found in dictionary\n", buffer);
    }

    close( welcomeSocket );
    close( newSocket );

    // TODO: other cleanup


    return 0;
}//end main

遇到C套接字程序陷入困境

1 个答案: