在我的套接字代码中，我有以下结构：
服务器：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define MAXPROFILES 2
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno, clilen;
struct sockaddr_in serv_addr, cli_addr;
unsigned char buf[1024];
char* pointer = buf;
struct profile_t
{
unsigned char length;
unsigned char type;
unsigned char *data;
};
typedef struct profile_datagram_t
{
unsigned char src[4];
unsigned char dst[4];
unsigned char ver;
unsigned char n;
struct profile_t profiles[MAXPROFILES];
} header;
header outObj;
int j =0;
int i =0;
if (argc < 2) {
fprintf(stderr,"usage: %s port_number1",argv[0]);
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR DETECTED !!! Problem in opening socket");
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(portno);
if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
error("ERROR DETECTED !!! There was a problem in binding");
listen(sockfd, 10);
clilen = sizeof(cli_addr);
printf("Server listening on port number %d...\n", serv_addr.sin_port);
newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR DETECTED !!! the connection request was not accepted");
int rc = read(newsockfd,&pointer,100);
if(rc < 0){
printf("error");
}
else {
printf("success %d",rc);
}
for(int i=0;i<29;i++){
printf(pointer);
printf(buf);
}
return 0;
}
客户端：
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
unsigned char buf[1024];
unsigned int srcAddress = 2193598184;
unsigned int destAddress = 2193598182;
struct profile_t
{
unsigned char length;
unsigned char type;
unsigned char *data;
};
typedef struct profile_datagram_t
{
unsigned char src[4];
unsigned char dst[4];
unsigned char ver;
unsigned char n;
struct profile_t profiles[MAXPROFILES];
} header;
header outObj;
int j =0;
int i =0;
// for loop for doing the malloc so that we can allocate memory to all profiles
for(i=0;i<MAXPROFILES;i++){
outObj.profiles[i].data = malloc(5);
}
for(i=0;i<4;i++){
outObj.src[i] = (srcAddress >> (i*8)) & 0xFF;
outObj.dst[i] = (destAddress >> (i*8)) & 0xFF;
}
outObj.ver = 1;
outObj.n = 2;
memcpy(buf,&outObj.src,4);
memcpy(buf+4,&outObj.dst,4);
memcpy(buf+8,&outObj.ver,1);
memcpy(buf+9,&outObj.n,2);
outObj.profiles[0].length = 5;
outObj.profiles[0].type = 1;
outObj.profiles[1].length = 5;
outObj.profiles[1].type = 2;
for(i=0;i<MAXPROFILES;i++){
for(j=0;j<5;j++){
outObj.profiles[i].data[j] = j+1;
}
}
int k = 11;
for(i=0;i<MAXPROFILES;i++){
memcpy(buf+k,&outObj.profiles[0].length,1);
memcpy(buf+k+1,&outObj.profiles[0].type,1);
memcpy(buf+k+2,outObj.profiles[0].data,5);
k +=7;
}
if (argc < 3) {
fprintf(stderr,"usage: %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]); //Convert ASCII to integer
sockfd = socket(AF_INET, SOCK_STREAM, 0); // socket file descriptor
if (sockfd < 0)
error("ERROR DETECTED !!! Problem in opening socket\n");
server = gethostbyname(argv[1]);
if (server == NULL) {
fprintf(stderr,"ERROR DETECTED !!!, no such server found \n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr)); //clear the memory for server address
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
printf("Client 1 trying to connect with server host %s on port %d\n", argv[1], portno);
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error("ERROR in connection");
printf("SUCCESS !!! Connection established \n");
if (write(sockfd, buf, k) < 0)
{
error("Write error has occured ");
}
return 0;
}
现在从客户端我对我的unsigned char buf进行memcpy并发送数据。在recv方面，如何访问我的“buf”中的值。我尝试了“*”运算符，但是我收到了警告
arning：传递âprintfâ的参数1使得整数中的指针没有强制转换
我想基本上访问缓冲区内的值，因为我知道我应该能够重新填充我的数据包的大小。我知道这是一个“C”问题而不是“套接字相关”。任何帮助都会非常有用。
答案 0 :(得分：1)
在服务器端，您只需要反转在客户端执行的操作：
你也没有使用char *pointer = buf获得任何东西，只是直接读入缓冲区。当您循环搜索MAXPROFILES时，只需检查buffer中与返回的size的当前位置，确保您没有读取未收到的数据。
例如：
int size = read(newsockfd, buffer, sizeof(buffer));
int src, dst;
char ver;
short n;
memcpy(&src, buf + 0, 4);
memcpy(&dst, buf + 4, 4);
memcpy(&ver, buf + 8, 1);
memcpy(&n, buf + 9, 2);
......等等......
您在客户端编码结构/数据，因此您必须在服务器端解码它们。一旦你这样做了，那么你可以打印它们或做你喜欢的任何事情：
printf("src: %d dst: %d ver: %c n: %d\n", src, dst, ver, n);
另外，为简化编码/解码，请使用相同的方法（例如memcpy而不是使用掩码方法逐字节）。例如，在客户端：
k = 0;
memcpy(buf + k, &src, sizeof(src)); k += sizeof(src);
memcpy(buf + k, &dst, sizeof(dst)); k += sizeof(dst);
...
这也让我从上面的硬编码数字中解脱了一些。只需确保您的src，dst以及其他所有客户端和服务器上的类型都相同。
答案 1 :(得分：0)
你的意思是gcc在这一行上发出警告：“int rc = read（newsockfd，＆amp; pointer，100）;”
你的变量“指针”本身是指向buf的指针，所以你不需要使用＆amp;指针，只需使用如下：
int rc = read（newsockfd，pointer，100）