我正在编写一个用于模拟服务器和客户端一次密码的程序。客户端发送明文或密文文件和密钥文件。服务器侦听一个客户端进程，该进程发送一个缓冲区，该缓冲区包含一个方法（加密（otp_enc）或解密（otp_dec））和两个文件名（input_file_name和key_file_name），程序打开文件并将纯文本或密文写入到文件中。缓冲并发送回客户端，以打印输出。
用户在命令行上调用：
otp_dec_d [port_number] & (server runs in background)
otp_dec plaintext_file_name key_file_name [port_number]
程序运行完美，除非我试图将退出状态设置为2（如果方法与端口号不匹配），就像这样...
otp_dec_d 56780 &
otp_enc_d 56781 &
otp_enc plaintext_file_name key_file_name 56780
而且我遇到了段错误。知道为什么吗？我指出了要这样做的内容。程序的其余部分工作正常，如果出现此错误，则空白输出将被发送回客户端。 （if（strcmp（argv [0]，method）！= 0）是if语句）
//header files
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include "otp.h"
void error(const char *msg) { perror(msg); exit(1); } // Error function used for reporting issues
/*
Name: server
-----------------
Description:
This function simulates a server
Reads buffer input from the client
Tokenizes string
Opens files for writing specified in arguments list
Calls appropriate function for encrypt/decrypt
Sends back an output file
Parameters:
argv[] list from stdin (ex: otp_dec_d or otp_enc_d [port_number])
*/
int server(char* argv[])
{
//printf("%s %s\n", argv[0], argv[1]); //for testing purposes
int listenSocketFD, establishedConnectionFD, portNumber, charsRead;
socklen_t sizeOfClientInfo;
char buffer[300];
struct sockaddr_in serverAddress, clientAddress;
pid_t spawnPid = -5; //garbage value
char method[100]; //array to hold method name (otp_enc,or otp_dec)
char input_file_name[100]; //array to hold input file name
char key_file_name[100]; //array to hold key file name
char output_file_name[300] = "output_file"; //array to hold output file name (output_file)
char input[70000]; //array to hold recv file contents
char output[70000]; //array to hold send file contents
char key[70000]; //array to hold key file contents
int port; //int value to hold argv[1]
// Set up the address struct for this process (the server)
memset((char *)&serverAddress, '\0', sizeof(serverAddress)); // Clear out the address struct
portNumber = atoi(argv[1]); // Get the port number, convert to an integer from a string
serverAddress.sin_family = AF_INET; // Create a network-capable socket
serverAddress.sin_port = htons(portNumber); // Store the port number
serverAddress.sin_addr.s_addr = INADDR_ANY; // Any address is allowed for connection to this process
// Set up the socket
listenSocketFD = socket(AF_INET, SOCK_STREAM, 0); // Create the socket
if (listenSocketFD < 0) error("ERROR opening socket");
// Enable the socket to begin listening
if (bind(listenSocketFD, (struct sockaddr *)&serverAddress, sizeof(serverAddress)) < 0) // Connect socket to port
error("ERROR on binding");
listen(listenSocketFD, 5); // Flip the socket on - it can now receive up to 5 connections
while(1) {
// Accept a connection, blocking if one is not available until one connects
sizeOfClientInfo = sizeof(clientAddress); // Get the size of the address for the client that will connect
establishedConnectionFD = accept(listenSocketFD, (struct sockaddr *)&clientAddress, &sizeOfClientInfo); // Accept
if (establishedConnectionFD < 0) error("ERROR on accept");
spawnPid = fork();
switch(spawnPid) {
case -1:
perror("Hull Breach!\n");
exit(1);
break;
case 0:
// Get the message from the client and display it
memset(buffer, '\0', strlen(buffer));
charsRead = recv(establishedConnectionFD, buffer, strlen(buffer)-1, 0); // Read the client's message from the socket
if (charsRead < 0) error("ERROR reading from socket");
//printf("SERVER: I received this from the client: \"%s\"\n", buffer);
//tokenize input from client
char* token = strtok(buffer, "\n");
strcpy(method, token); //transfer current value to method array
token = strtok(NULL, "\n"); //reset token
strcpy(input_file_name, token); //transfer current value to input_file_name array
token = strtok(NULL, "\n"); //reset token
strcpy(key_file_name, token); //transfer current value to key_file_name array
//printf("%s %s %s %s\n", method, input_file_name, key_file_name); //for testing purposes
//printf("%d\n", port); //for testing purposes
strcat(method, "_d"); //add _d to end of method
if(strcmp(argv[0], method) != 0) {
fprintf(stderr, "Error: could not contact %s on %s", argv[0], argv[1]);
exit(2); //SEG_FAULT HERE!!!!!
}
else {
//open input and key files for reading
FILE* input_file = fopen(input_file_name, "r");
FILE* key_file = fopen(key_file_name, "r");
//transfer file contents to arrays
fgets(input, 70000, input_file);
fgets(key, 70000, key_file);
//close files
fclose(input_file);
fclose(key_file);
//remove trailing newlines from arrays
input[strcspn(input, "\n")] = '\0';
key[strcspn(key, "\n")] = '\0';
//printf("%s\n%s\n", input, key); //for testing purposes
//printf("%s\n", argv[0]);
//printf("%s\n", method); //for testing purposes
/* --------------------- Handle encrypt v. decrypt --------------------- */
//if argument 1 in argv array is encrypt
if(strcmp("otp_enc_d", method) == 0)
encrypt(input, output, key);
//else if argument 1 in argv array is decrypt
else if(strcmp("otp_dec_d", method) == 0)
decrypt(input, output, key);
/* ------------------- End handle encrypt v. decrypt ------------------- */
}
//printf("%s\n", output); //for testing purposes
//Open output file and write contents to it
FILE* output_file = fopen(output_file_name, "w+");
fprintf(output_file, "%s", output);
// Send a Success message back to the client
charsRead = send(establishedConnectionFD, output_file_name, strlen(output_file_name), 0); // Send success back
//printf("%d\n", charsRead);
if (charsRead < 0) error("ERROR writing to socket");
// Close the existing socket which is connected to the client
close(establishedConnectionFD);
establishedConnectionFD = -1;
exit(0);
break;
default: ;
}
close(establishedConnectionFD);
establishedConnectionFD = -1;
wait(NULL);
}
close(listenSocketFD); // Close the listening socket
return 0;
}