我有这个ftserver.c程序,它正在实现一个文件传输服务器,它监听客户端,然后通过数据连接响应客户端请求。现在它可以工作,但我有硬编码数据连接的主机名和端口号。 portnumber由客户端提供,服务器应该能够从客户端的控制连接中获取主机名。
参考文献:http://beej.us/guide/bgnet/output/html/multipage/getaddrinfoman.html
如何动态分配主机名和端口号?谢谢。
void error(const char *msg)
{
perror(msg);
exit(1);
}
void startup(int portNumber);
void setupData(char* portNum);
int sockfd, newsockfd, datasock, portno;
char buffer[256]; socklen_t clilen;
struct sockaddr_in serv_addr, cli_addr, port_addr;
struct addrinfo hints, *servinfo, *p;
char ipstr[1000];
struct in_addr ipAddr;
struct sockaddr_in *s;
int main(int argc, char *argv[]){
int n; char* dataport; char * token; char filename[100];
if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
portno = atoi(argv[1]);
startup(portno);
n = read(newsockfd,buffer,255);
if (n < 0) error("ERROR reading from socket");
printf("Here is the message: %s\n",buffer);
token = strtok(buffer, " ");
//if client requested a list, setup data connection and send it
if (strcmp(token, "-l") == 0){
token = strtok(NULL, " ");
printf("the token is %s\n", token);
//dataport = atoi(token);
dataport = token;
setupData(dataport);
//sendList(dataport);
}
//if client requested a file, setup data connection and send it
else if (strcmp(token, "-g") == 0){
token = strtok(NULL, " ");
//filename = *token;
token = strtok(NULL, " ");
//dataport = atoi(token);
printf("the data port is %d\n", dataport);
//setupData(dataport);
//sendFile(filename, dataport);
}
else {
n = write(newsockfd,"not a valid command",19);
if (n < 0) error("ERROR writing to socket");
}
//close sockets for connection P
close(datasock);
close(newsockfd);
close(sockfd);
return 0;
}
void startup(int portNumber)
{
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portNumber);
if (bind(sockfd, (struct sockaddr *) &serv_addr,
sizeof(serv_addr)) < 0)
error("ERROR on binding");
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,
(struct sockaddr *) &cli_addr,
&clilen);
if (newsockfd < 0)
error("ERROR on accept");
bzero(buffer,256);
}
void setupData(char* portNum){
int rv;
const char* name = "localhost";
char s[1000];
memset(&hints, 0, sizeof (hints));
hints.ai_family = AF_UNSPEC; // use AF_INET6 to force IPv6
hints.ai_socktype = SOCK_STREAM;
if ((rv = getaddrinfo(name, "30024", &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
exit(1);
}
// loop through all the results and connect to the first we can
for(p = servinfo; p != NULL; p = p->ai_next) {
if ((datasock = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("socket");
continue;
}
if (connect(datasock, p->ai_addr, p->ai_addrlen) == -1) {
perror("connect");
close(sockfd);
continue;
}
break; // if we get here, we must have connected successfully
}
if (p == NULL) {
// looped off the end of the list with no connection
fprintf(stderr, "failed to connect\n");
exit(2);
}
printf("data connection setup successful\n");
}
答案 0 :(得分:0)
我已经解决了这个问题。通过使用设置数据连接的简化版本,不使用getaddrinfo()和使用hostname_to_ip转换函数。参考:http://www.linuxhowtos.org/data/6/client.c
int setupData(char* hostname, char* portNum){
int sock_fd; char ip[100];
struct sockaddr_in srv_addr;
memset(&srv_addr, 0, sizeof(srv_addr)); /* zero-fill srv_addr structure*/
/* create a client socket */
sock_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
srv_addr.sin_family = AF_INET; /* internet address family */
/* convert command line argument to numeric IP */
hostname_to_ip(hostname, ip);
printf("%s resolved to %s" , hostname , ip);
if ( inet_pton(AF_INET, ip, &(srv_addr.sin_addr)) < 1 )
{
printf("Invalid IP address\n");
exit(EXIT_FAILURE);
}
srv_addr.sin_port = htons(atoi(portNum));
if( connect(sock_fd, (struct sockaddr*) &srv_addr, sizeof(srv_addr)) < 0 )
{
perror("connect error");
exit(EXIT_FAILURE);
}
return sockfd;
}