c中的套接字编程，发送项目列表

Question

我在c中创建了一个模拟航空公司的服务器/客户端tcp连接。我在从服务器向客户端发送航班列表时遇到问题，我当时只能发送一串字符，而且我实施的代码无效，给我一个分段错误，有人可以给我一些内幕吗？

这是服务器，send_all（）函数将使用套接字ID和hashmap逐行发送带有write（）函数的航班列表。

    int send_all(int socket, map_t flight_map)
    {
        struct hashmap_element {
            char* key;
            int in_use;
            any_t data;
        };

        struct hashmap_map {
            int table_size;
            int size;
            struct hashmap_element *data;
        };

        struct hashmap_map * map = (struct hashmap_map *) flight_map;

        //int index = map->tableSize;
        char line[12];
        int i = 0;
        for (i = 0; i < map->table_size; i++)
        {
            strcpy(line, return_flight(map->data[i].key, map->data[i].data));
            if (write(socket, line, strlen(line) + 1) < 0) {
                        error("error: writing to connection");
                        return 0;
            }
        }
        return 1;
    }
    char * return_flight(char * flight, void * seats) 
    {
        char tmp[20];
        strcpy(tmp, flight);
        strcat(tmp, (char *)seats);
        return tmp;
    }

以下是客户端： readSocket，负责读取通过套接字连接传递的每一个字符串...

// send input to server
        if (write(client_fd, command, strlen(command) + 1) < 0)
            error("error: writing to socket");

        printf("client: sending %s to server\n", command);

        // recieve response from server
        if (readSocket(client_fd, buffer) < 0)
            error("error: reading from socket");

        printf("client: read %s from server\n", buffer);

        printf("client: closing client\n");
        close(client_fd);
    }

    return 0;
}

static int readSocket(int socket, char *buffer)
{
     ssize_t bytes_read = 0;

     bytes_read = recv(socket, buffer, BUFSIZE - 1, 0);

     while (bytes_read > 0)
     {
         buffer[bytes_read] = 0; // Null-terminate the buffer
         printf("Buffer: %s\n", buffer);
         bytes_read = recv(socket, buffer, BUFSIZE - 1, 0);
     }
     if (bytes_read == -1)
     {
         fprintf("Socket recv failed: %s\n", strerror(errno));
         return -1;
     }
     return 0;
}