【发布时间】：2017-10-13 13:50:31
【问题描述】：
我正在尝试实现一个简单的代理服务器，到目前为止一切顺利，我已经成功地正确执行了 GET 方法，但现在我必须为它实现一个缓存。它背后的想法是当我收到以下命令时：
- 获取 www.google.com
- 获取 www.cplusplus.com
- 获取 www.google.com
我第二次被要求从谷歌获取信息，它应该来自我的缓存系统。我一直在考虑，最好的方法是实现一个简单的文件系统，我将收到的信息存储在文件中，然后在发现文件存在时读取它。我遇到的唯一麻烦是我无法创建诸如http://elf.cs.edu.ro/ 之类的文件
这是我的代码，所以你明白我在做什么。
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
void error(char* msg) {
perror(msg);
exit(0);
}
int main(int argc,char* argv[]) {
int count = 0;
FILE *in;
FILE *out;
pid_t pid;
struct sockaddr_in addr_in,cli_addr,serv_addr;
struct hostent* host;
int sockfd,newsockfd;
if(argc<2)
error("./proxy <port_no>");
printf("\n*****WELCOME TO PROXY SERVER*****\n");
bzero((char*)&serv_addr,sizeof(serv_addr));
bzero((char*)&cli_addr, sizeof(cli_addr));
serv_addr.sin_family=AF_INET;
serv_addr.sin_port=htons(atoi(argv[1]));
serv_addr.sin_addr.s_addr=INADDR_ANY;
sockfd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(sockfd<0)
error("Problem in initializing socket");
if(bind(sockfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr))<0)
error("Error on binding");
listen(sockfd,50);
int clilen=sizeof(cli_addr);
startpoint:
newsockfd=accept(sockfd,(struct sockaddr*)&cli_addr,&clilen);
if(newsockfd<0)
error("Problem in accepting connection");
pid=fork();
//printf("Pid is: %d\n", pid);
if(pid==0) {
sites saves[10];
int noOfSites = 0;
struct sockaddr_in host_addr;
int flag=0,newsockfd1,n,port=0,i,sockfd1;
char buffer[510],t1[300],t2[300],t3[10], aux[510];
char* temp=NULL;
bzero((char*)buffer,500);
recv(newsockfd,buffer,sizeof(buffer),0);
//printf("%s\n",buffer);
sscanf(buffer,"%s %s %s",t1,t2,t3);
//printf("%s\n",buffer);
if (((strncmp(t1,"GET",3)==0))&&((strncmp(t3,"HTTP/1.0",8)==0)||(strncmp(t3,"HTTP/1.0",8)==0))&&(strncmp(t2,"http://",7)==0)) {
strcpy(t1,t2);
int saved = 0;
flag=0;
for(i=7;i<strlen(t2);i++) {
if(t2[i]==':') {
flag=1;
break;
}
}
// printf("The site to GET is : %s\n",t2);
temp=strtok(t2,"//");
if (flag==0) {
port=80;
temp=strtok(NULL,"/");
}
else {
temp=strtok(NULL,":");
}
sprintf(t2,"%s",temp);
host=gethostbyname(t2);
int it;
for (it = 0; it < noOfSites; it++){
printf("Site saved is: %s\n", saves[it].site);
if (strcmp(saves[it].site,t2) == 0){
saved = 1;
out = fopen(t2, "r");
printf("We have cache!\n");
}
}
if(flag==1) {
temp=strtok(NULL,"/");
port=atoi(temp);
}
strcat(t1,"^]");
temp=strtok(t1,"//");
temp=strtok(NULL,"/");
if(temp!=NULL)
temp=strtok(NULL,"^]");
bzero((char*)&host_addr,sizeof(host_addr));
host_addr.sin_port=htons(port);
host_addr.sin_family=AF_INET;
bcopy((char*)host->h_addr,(char*)&host_addr.sin_addr.s_addr,host->h_length);
sockfd1=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
newsockfd1=connect(sockfd1,(struct sockaddr*)&host_addr,sizeof(struct sockaddr));
sprintf(buffer,"\nConnected to %s IP - %s\n",t2,inet_ntoa(host_addr.sin_addr));
if(newsockfd1<0)
error("Error in connecting to remote server");
bzero((char*)buffer,sizeof(buffer));
if(temp!=NULL)
sprintf(buffer,"GET /%s %s\r\nHost: %s\r\nConnection: close\r\n\r\n",temp,t3,t2);
else
sprintf(buffer,"GET / %s\r\nHost: %s\r\nConnection: close\r\n\r\n",t3,t2);
if (saved == 1){
printf("Are we ever here\n");
n = send(sockfd1,buffer,strlen(buffer),0);
char * line = NULL;
size_t len = 0;
ssize_t read;
int count = 0;
if (n<0)
error("Error writing to socket");
else {
while ((read = getline(&line, &len, out)) != -1) {
//printf("Retrieved line of length %zu :\n", read);
if (count > 0)
write(newsockfd,line,read);
if (strcmp(line,"\r\n") == 0)
count++;
}
}
}
if (saved == 0){
//printf("We are only here\n");
strcpy(saves[noOfSites].site,t2);
noOfSites++;
printf("The new site file is: %d\n", noOfSites);
in = fopen(t2,"w");
n=send(sockfd1,buffer,strlen(buffer),0);
printf("I have opened for writing: %s\n\n\n\n\n\n",t2);
if(n<0)
error("Error writing to socket");
else {
do {
memset(buffer, 0, sizeof(buffer));
n=recv(sockfd1,buffer,sizeof(buffer),0);
fwrite(buffer, n, 1, stdout);
printf("\n");
fwrite(buffer, n, 1, in);
if(!(n<=0))
write(newsockfd,buffer,n);
} while(n>0);
}
}
}
else {
send(newsockfd,"400 : BAD REQUEST\nONLY HTTP REQUESTS ALLOWED",18,0);
}
close(sockfd1);
close(newsockfd);
close(sockfd);
fclose(in);
return 0;
}
else {
close(newsockfd);
goto startpoint;
}
return 0;
}
谁能指出我正确的方向？我不希望有人为我做这件事，只是想知道你会如何做，这样我才有机会。感谢您的宝贵时间！
【问题讨论】：
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寻求调试帮助的问题（“为什么这段代码不起作用？”）必须包括所需的行为、特定的问题或错误以及必要的最短代码 在问题本身中重现它。没有明确问题陈述的问题对其他读者没有用处。见：How to create a Minimal, Complete, and Verifiable example.
标签： c caching network-protocols