我从Github下载了一个C ++程序，它使用Pair对算法进行带宽估计。我已经在我的系统上编译和安装了程序，但是当我初始化Bind（）函数以绑定到端口53时，它表示Bind（）失败或无限“等待客户端”。我对套接字编程和使用BIND不是很熟悉。是否有一些规则在起作用？
如果需要，这是程序源： https://github.com/npbendre/Bandwidth-Estimation-using-Packet-Pair-Probing-Algorithm
/********************************************************
* Program: Bandwidth Estimation *
* *
* Summary: *
* This file contains the server code *
* *
*********************************************************/
#include "defs.h"
int quit = 0; /* CNT-C exit flag */
#define RESET 0
#define HEX 16
#define MSZ_BEGIN 5
#define SEQ_BEGIN 5
#define BSZ_BEGIN 9
#define MAX_WAIT 30
#define HEADER_SIZE 28
#define TO_Mbits(x) (x*8/1048576)
struct Client {
int cmd;
char sessionID[ID_LEN+1];
unsigned int msgSize;
unsigned int seq;
unsigned int burstSize;
unsigned int burstCnt;
unsigned int numRecv;
double bandwidth;
};
/* SIGINT handler */
void CNT_C_Code()
{
printf("CNT-C Interrupt, exiting...\n");
quit = 1;
}
/* SIGALRM handler */
void alarmHandler() { }
int main(int argc, char *argv[])
{
int sock; /* Socket */
struct sockaddr_in serverAddr; /* Local address */
struct sockaddr_in clientAddr; /* Client address */
struct sockaddr_in dupClAddr; /* Temporary address */
unsigned int addrLen; /* Client address length */
unsigned int serverPort; /* Local port */
struct sigaction sa_int; /* For SIGINT */
struct sigaction sa_alrm; /* For SIGALRM */
int cmd = RESET; /* Server commands */
char buffer[MIN_MSG_LEN]; /* Receive buffer */
char results[RESULT_LEN]; /* Results buffer */
char *msg = NULL; /* Client message */
struct Client cl; /* Current client */
int recvlen; /* Received message length */
int seq; /* Sequence number */
struct timespec ts1; /* time structure */
struct timespec ts2; /* time structure */
struct timespec *ts = NULL; /* Switch pointer */
int swtch = 0; /* Switch flag for timespecs */
int cnt = 0;
char temp[ID_LEN+1];
/* Invalid invocation of the program */
if (argc != 2) {
printf("Syntax: %s <port number>\n", argv[0]);
exit(1);
}
serverPort = atoi(argv[1]);
/* create datagram socket */
if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
DieWithError("socket() failed");
/* build local address struct */
memset(&serverAddr, 0, sizeof(serverAddr));
serverAddr.sin_family = AF_INET;
serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
serverAddr.sin_port = htons(serverPort);
/* bind to local address */
printf("Server: binding to port %d\n", serverPort);
if (bind(sock, (struct sockaddr *) &serverAddr, sizeof(serverAddr)) < 0) {
close(sock);
DieWithError("bind() failed");
}
/* assign handler and initialize set to all signals */
sa_int.sa_handler = CNT_C_Code;
sa_alrm.sa_handler = alarmHandler;
if (sigfillset(&sa_int.sa_mask) < 0 || sigfillset(&sa_alrm.sa_mask) < 0) {
close(sock);
DieWithError("sigfillset() failed");
}
/* set the handler */
sa_int.sa_flags = sa_alrm.sa_flags = 0;
if (sigaction(SIGINT, &sa_int, 0) < 0 || sigaction(SIGALRM, &sa_alrm, 0) < 0) {
close(sock);
DieWithError("sigaction() failed");
}
addrLen = sizeof(struct sockaddr_in);
/* Run until CNT-C */
for ( ; !quit; ) {
if (cmd == RESET) {
/* reset session id */
memset(&cl, 0, sizeof(cl));
errno = swtch = cnt = 0;
ts = &ts1;
printf("Waiting for Client...\n");
/* get the first message from client */
recvfrom(sock, buffer, MIN_MSG_LEN, 0, (struct sockaddr *) &clientAddr, &addrLen);
if (errno == EINTR) continue;
memcpy(&dupClAddr, &clientAddr, addrLen);
cl.cmd = buffer[0]-'0'; /* get the client command */
}
/* Received START_MSG, send START_ACK */
if (cl.cmd == START_MSG) {
getFromMsg(cl.sessionID, buffer, SID_BEGIN, ID_LEN); /* retrieve session ID */
getFromMsg(temp, buffer, MSZ_BEGIN, ID_LEN); /* retrieve message size */
cl.msgSize = strtol(temp, NULL, HEX);
getFromMsg(temp, buffer, BSZ_BEGIN, ID_LEN); /* retrieve burst size */
cl.burstSize = strtol(temp, NULL, HEX);
if (!msg) msg = (char *) calloc(cl.msgSize+1, sizeof(char));
printf("\n");
printf("Serving client with session ID: %s\n", cl.sessionID);
/* set sending buffer to START_ACK */
cmd = START_ACK;
*msg = cmd + '0';
strcpy(msg+SID_BEGIN, cl.sessionID);
/* send START_ACK to client */
printf("=== Received START_MSG, sending START_ACK...\n");
sendto(sock, msg, strlen(msg)+1, 0, (struct sockaddr *) &clientAddr, addrLen);
}
if (cmd == START_ACK) {
int once = 1;
/* accept client bursts */
for ( ; ; ) {
alarm(MAX_WAIT); /* wait till client sends next message, used when client crashes */
recvlen = recvfrom(sock, msg, cl.msgSize+1, 0, (struct sockaddr*) &dupClAddr, &addrLen);
clock_gettime(CLOCK_REALTIME, ts); /* get time */
if (errno == EINTR) {
if (!quit) {
free(msg);
msg = NULL;
cl.cmd = cmd = RESET;
printf("Server Timeout: Resetting...\n\n");
}
break;
}
alarm(0);
if (recvlen != cl.msgSize+1) /* damaged packet */
continue;
/* wrong client */
if (memcmp(&dupClAddr, &clientAddr, addrLen) || strncmp(cl.sessionID, msg+SID_BEGIN, ID_LEN))
break;
if ((cl.cmd = *msg-'0') == START_MSG) /* client did not receive START_ACK */
break;
if (cl.cmd == DONE) { /* Client done bursting */
cmd = RESULTS_MSG;
break;
}
++cl.numRecv;
ts = ((swtch = 1-swtch)) ? &ts2 : &ts1; /* switch time pointer */
getFromMsg(temp, msg, SEQ_BEGIN, ID_LEN); /* get sequence number */
seq = strtol(temp, NULL, HEX);
/* change in sequence */
if (seq != cl.seq) {
once = 1;
cl.seq = seq;
ts = &ts1;
swtch = 0;
++cl.burstCnt;
printf("=== Receiving from burst #%d...\n", cl.seq);
}
else {
/* get time interval only if its from the same burst sequence */
if (once) {
once = 0;
continue;
}
/* calculate average bandwidth */
cl.bandwidth *= cnt++;
cl.bandwidth += ((double) cl.msgSize+1+HEADER_SIZE) /
((swtch) ? getTimeDiff(ts1, ts2) : getTimeDiff(ts2, ts1));
cl.bandwidth /= (double) cnt;
}
/* not retrieving data from message */
}
}
if (cmd == RESULTS_MSG) {
float totExpected = cl.burstSize * cl.burstCnt;
/* create results */
results[0] = cmd + '0';
sprintf(results+SID_BEGIN, "%s:%f:%.2f:%u:%u", cl.sessionID, TO_Mbits(cl.bandwidth),
((totExpected-cl.numRecv)/totExpected)*100, cl.numRecv, cl.burstCnt);
printf("\n");
printf("=== Received DONE, sending RESULTS_MSG...\n");
sendto(sock, results, RESULT_LEN, 0, (struct sockaddr *) &dupClAddr, addrLen);
alarm(MAX_WAIT);
recvfrom(sock, msg, cl.msgSize+1, 0, (struct sockaddr *) &dupClAddr, &addrLen);
if (errno == EINTR) {
if (!quit) {
free(msg);
msg = NULL;
cmd = RESET;
printf("Server Timeout: Resetting...\n\n");
}
continue;
}
alarm(0);
/* wrong client */
if (memcmp(&dupClAddr, &clientAddr, addrLen) || strncmp(cl.sessionID, msg+SID_BEGIN, ID_LEN))
continue;
if (*msg-'0' == DONE) /* client did not receive RESULTS_MSG */
continue;
if (*msg-'0' == DONE_ACK) { /* received DONE_ACK from client */
printf("=== Received DONE_ACK.\n\n");
free(msg);
msg = NULL;
cmd = RESET;
}
}
}
if (msg) free(msg);
close(sock);
return 0;
}
答案 0 :(得分：1)
尝试端口号大于1024 - 对于非特权应用程序，操作系统可能阻止对较低编号端口的绑定。