在strcpy之后具有重复值的char []

Posted 2021-04-17

我有一个带有两个char数组变量（id和id_partner_expected）的结构，当我在第二个数组上使用strcpy时，第一个数组也会被更改。我尝试了所有我知道的，但没有预期的结果:(

#define SIZE_CLIENT_ID 15

struct client_infos {
    char addr[INET_ADDRSTRLEN];
    int socket;
    char id[SIZE_CLIENT_ID];
    char id_partner_expected[SIZE_CLIENT_ID];
    struct client_infos* partner;
};

char buffer_received[MAX_CLIENT_IO];


while ((len_received = recv(c->socket, buffer_received, MAX_CLIENT_IO, 0)) > 0) {

    if (strlen(c->id) == 0) {
        //First step: Identify the client

        strcpy(c->id, buffer_received); // FIRST LOOP

    } else if (strlen(c->id_partner_expected) == 0) {
        //Second step: Identify/Connect the partner


        strcpy(c->id_partner_expected, buffer_received); // SECOND LOOP

    }

    printf("Received %d bytes from client %s, with id %s", len_received, c->addr, c->id);
    printf("%d
", strlen(c->id));//STRCPY DUPLICATING CONTENT OF C->ID ???!!!
}

结果：

1º循环：

从客户端0.0.0.0收到15个字节，ID为0000654987321 15

2º循环：

从客户端0.0.0.0收到15个字节，ID为0000654987321 6544sssss5555 30

但预期的结果是：

2º循环：

从客户端0.0.0.0收到15个字节，ID为0000654987321 15

原始来源：https://github.com/fernandobatels/blitz-p2p-bridge/blob/master/src/api.h https://github.com/fernandobatels/blitz-p2p-bridge/blob/master/src/api.c

谢谢你的帮助:)

答案

C字符串零终止。从网络收到的字符串显然不是。接收数据后，您需要对字符串进行零终止：

...
while ((len_received = recv(c->socket, buffer_received, MAX_CLIENT_IO, 0)) > 0) {
    buffer_received[len_received] = 0; // add this line
    if (strlen(c->id) == 0) {
    ...

另请注意，由于您的最大ID长度（以及从网络接收的最大数据量）为15，您需要将数组扩展一个字符，以便为终止零点腾出空间：

struct client_infos {
    char addr[INET_ADDRSTRLEN];
    int socket;
    char id[SIZE_CLIENT_ID + 1];
    char id_partner_expected[SIZE_CLIENT_ID + 1];
    struct client_infos* partner;
}

char buffer_received[MAX_CLIENT_ID + 1];