recv（）直到收到NUL字节？
我试图从服务器一次接收一个数据包，因为数据包速度太快，每个都是未定义的大小，调用recv（）读取的字节数将读取第一个数据包，也许是一部分第二个包。由于每个数据包都是NULL终止的，我以为逐字节读取，直到收到一个NULL字节。
int recvLen = 0;
char TB;
char recvBuffer[1024];
while (recv(Socket, &TB, 1, 0) > 0 && TB != 0 && recvLen < 1024)
{
recvBuffer[recvLen] = TB;
recvLen++;
}
recv()
#define UPLOAD_LEN 2755
int PacketSize, recvLen;
char Size[4];
char recvBuffer[UPLOAD_LEN+1];
while(1)
{
if(recv(Socket,Size,4,0)>0)
{
Size[4] = ' ';
PacketSize = atoi(Size);
if (PacketSize > UPLOAD_LEN || PacketSize <= 0) continue;
recvLen = recv(Socket, recvBuffer, PacketSize, 0);
} else recvLen = -1;
if (recvLen > 0)
{
recvBuffer[recvLen] = ' ';
ProcessData(recvBuffer);
}
else
{
closesocket(Socket);
}
}
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#include <winsock2.h> #include <string.h> typedef struct buffsock { SOCKET s; char* buf; size_t maxlen; size_t curlen; } buffsock_t; void buffsock_init(buffsock_t* bs,SOCKET s,size_t maxlen) { bs->s = s; bs->buf = malloc(maxlen); bs->maxlen = maxlen; bs->curlen = 0; } void buffsock_free(buffsock_t* bs) { free(bs->buf); bs->buf = NULL; bs->maxlen = 0; bs->curlen = 0; bs->s = INVALID_SOCKET; } /* Attempt to fill internal buffer. * Returns 0 if socket closed. * Returns number of additional bytes in buffer otherwise. */ int buffsock_fill(buffsock_t* bs) { int bytes; bytes = recv(bs->s,bs->buf + bs->curlen,bs->maxlen - bs->curlen,0); if(bytes == SOCKET_ERROR) return -1; bs->curlen += bytes; return bytes; } /* Return up to <bytes> from buffered socket. * If return value 0 socket was closed. * If return value >0 and <bytes socket received partial message. */ int buffsock_bytes(buffsock_t* bs,size_t bytes,void* msg) { while(bs->curlen < bytes) { int result; result = buffsock_fill(bs); if(result == -1) return -1; /* error on socket */ if(result == 0) break; } if(bytes > bs->curlen) bytes = bs->curlen; memcpy(msg,bs->buf,bytes); bs->curlen -= bytes; memmove(bs->buf,bs->buf + bytes,bs->curlen); return bytes; } /* Implmementation of a protocol with two big-endian bytes indicating * msg size followed by <size> bytes of message. * Returns -1 if error on socket. * Returns -2 if partial message recv'd (shouldn't happen as long as * internal buffer is bigger than max message size). * Returns -3 if user buffer not big enough to hold message. * Returns size of message otherwise. */ int get_protocol_message(buffsock_t* bs,void* msg,size_t maxlen) { int bytes; u_short len; bytes = buffsock_bytes(bs,sizeof(u_short),&len); if(bytes == 0) return 0; /* socket closed, no more messages */ if(bytes == -1) return -1; /* error on socket */ if(bytes < sizeof(u_short)) return -2; /* partial message */ len = ntohs(len); if(len > maxlen) return -3; /* message exceeds user buffer */ bytes = buffsock_bytes(bs,len,msg); if(bytes < len) return -2; /* partial message */ return bytes; }关键是TCP / IP没有消息边界的概念，因此recv（）可以返回1到请求的字节数。收到的缓冲区可能包含多个甚至部分消息。 此代码只是将接收到的数据附加到缓冲区中。协议从缓冲区请求字节，缓冲区从套接字填充。当字节被移除时，剩余的缓冲数据被移位到缓冲区的开头。 在这种情况下，请求两个字节，转换为长度，然后请求剩余的字节。如果无法满足请求，则会收集更多数据。 希望这可以帮助。扑北爱
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