C变量和内存问题

Question

我的代码有问题，变量 receiver_buffer 从 json_packet 或函数 external_auth_format_packet 中的 uu 获取一些数据。

这里在日志中可以看到:

Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: socket_path: /tmp/auth.sock
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: json_packet: {"user": "root", "key": "AAAAB3NzaC1yc2EAAAADAQABAAABAQDwHDG/TpoUDts9CFrUWh6eoOlPcQYTLIpkF1udDaRZMsdZSZyDsWO5otqrUiQuVLFBXKa4CMiYBJIll2Ye/ZMWjbWd6mkrhE/u4Ha+DS6wyoza3mgn4ekDYxHqzk6/9kVnNtdh+sw3h0OwhkJJG/fAGzGFZhaV5bRS8f9u6pxIKTdmUfozkfe/QhYlFS9gaFnlK2rn8efK1oeNL00YBEcFLVeFdFqU9xuTOrHIQuOHxEynF/zekJ69D1MDhLZDhzq7mfy00wOnS51Q0gxZUdBiFr0ahuD/WrxKgwYunAsp1hD22+WU89vmoPtonWE7a6hTeZtz6Mb0YPfmRwz+CaR1", "type": "ssh-rsa"}
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: sent json_packet to server
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: receiver_buffer memory allocation
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: recv has received: {"status":1,"command":"command='./gitserve' "}
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: copying from tmp_buffer to receiver_buffer
Sep 26 12:35:07 ubuntu sshd[58912]: userauth_external: DEBUG: finished receiving data from socket
Sep 26 12:35:07 ubuntu sshd[58912]: error: userauth_external: ERROR: Unable to load parmaters! error: on line 1: end of file expected near 'rUWh'\n
Sep 26 12:35:07 ubuntu sshd[58912]: error: userauth_external: ERROR: response {"status":1,"command":"command='./gitserve' "}rUWh6eoOlPcQYTLIpkF1udDaRZMsdZSZyDsWO5otqrUiQuVLFBXKa4CMiYBJIll2Ye/ZMWjbWd6mkrhE/u4Ha+DS6wyoza3mgn4ekDYxHqzk6/9kVnNtdh+sw3h0OwhkJJG/fAGzGFZhaV5bRS8f9u6pxIKTdmUfozkfe/QhYlFS9gaFnlK2rn8efK1oeNL00YBEcFLVeFdFqU9xuTOrHIQuOHxEynF/zekJ69D1MDhLZDhzq7mfy00wOnS51Q0gxZUdBiFr0ahuD/WrxKgwYunAsp1hD22+WU89vmoPtonWE7a6hTeZtz6Mb0YPfmRwz+CaR1

从socket receiver_buffer接收数据

{"status":1,"command":"command='./gitserve' "}

然后 jansson 尝试将它看到的数据解析为不属于该变量的数据

{"status":1,"command":"command='./gitserve' "}rUWh6eoOlPcQYTLIpkF1udDaRZMsdZSZyDsWO5otqrUiQuVLFBXKa4CMiYBJIll2Ye/ZMWjbWd6mkrhE/u4Ha+DS6wyoza3mgn4ekDYxHqzk6/9kVnNtdh+sw3h0OwhkJJG/fAGzGFZhaV5bRS8f9u6pxIKTdmUfozkfe/QhYlFS9gaFnlK2rn8efK1oeNL00YBEcFLVeFdFqU9xuTOrHIQuOHxEynF/zekJ69D1MDhLZDhzq7mfy00wOnS51Q0gxZUdBiFr0ahuD/WrxKgwYunAsp1hD22+WU89vmoPtonWE7a6hTeZtz6Mb0YPfmRwz+CaR1`

函数源码 http://pastebin.com/P7WnhsqX

Answer 1

memcpy(receiver_buffer + total_received_chars, tmp_buffer, received_chars);

您正在复制 received_chars 字节，这是字符串长度 - 它不包括终止 '\0' 字节。稍后，当您尝试使用它时 - 您拥有字符串 + 缓冲区的其余部分，因为您不知道需要读取多少内容。