SimpleRouter: the problem

本文介绍了简单规则路由器软件的实现,路由器规则有ACCEPT、REJECT、FORWARD三种形式。根据规则判断数据包来源IP和端口范围,若多规则适用则取最后一条,无适用规则则拒绝。还给出了不同规则和数据包示例及处理结果。
Problem Statement

A router's job is to route packets of information to the correct computer. In addition, a router may throw out some packets, or handle the packets on its own. In this problem, you are to implement the software for a simple, rule-based router. Each rule in the router will take one of the following forms (quotes and angle brackets for clarity only):

"ACCEPT <IP_RANGE> <PORT_RANGE>"
"REJECT <IP_RANGE> <PORT_RANGE>"
"FORWARD <IP_RANGE> <PORT_RANGE> <DESTINATION> (<PORT>)"

Each <IP_RANGE> is a string of exactly four <NUMBER_RANGE>s, separated by periods, and each <PORT_RANGE> consists of a single <NUMBER_RANGE>. A <NUMBER_RANGE> can take one of three forms. It may be a single integer, a range of integers (in the form "<LOWER_LIMIT>-<UPPER_LIMIT>", where both limits are inclusive), or an asterisk. <DESTINATION> consists of exactly 4 integers, with 3 periods separating them (an IP address). If a FORWARD rule has a <PORT_RANGE> with only a single integer, then the <DESTINATION> may optionally be followed by a single integer, <PORT>. Each rule tells the router what to do with a packet of information if that packet comes from an IP in the rule's <IP_RANGE> and to a port in the rule's <PORT_RANGE>. An IP is in the <IP_RANGE> if each <NUMBER_RANGE> in the <IP_RANGE> matches the corresponding number in the IP. A <NUMBER_RANGE> matches a number, N, if the <NUMBER_RANGE> is an asterisk, if it is a single number that is the same as N, or if it is a range and N falls within the range, inclusive. The rules for matching a <PORT_RANGE> are the same. If a rule tells the router to forward the packet, then it should be forwarded to <DESTINATION>. If no <PORT> is specified, the packet should be forwarded to the same port it was received on. Otherwise, it should be forwarded to the specified port. If multiple rules apply to a packet, you should use the one that comes last in the input. If no rules apply, REJECT the packet. You will be given a String[], rules, representing a number of rules that the router is to follow. You will also be given a String[], packets, each of whose elements represents a packet of data in the form "<SOURCE_IP> <PORT>" (<SOURCE_IP> is formatted the same as <DESTINATION>). You should return a String[] with one element per packet, specifying what to do with the packet with the same index in the input as the return. Each element of the return should be either "ACCEPT", "REJECT", or "<IP>:<PORT>", where <IP> and <PORT> represent the location to which the packet should be forwarded.
Definition

Class:
SimpleRouter
Method:
route
Parameters:
String[], String[]
Returns:
String[]
Method signature:
String[] route(String[] rules, String[] packets)
(be sure your method is public)


Notes
-
While the input may have extraneous leading zeros, your return should not.
Constraints
-
rules will contain between 1 and 50 elements, inclusive.
-
Each element of rules will be formatted as described in the problem statement.
-
packets will contain between 1 and 50 elements, inclusive.
-
Each element of packets will be formatted as described in the problem statement.
-
Each of the four numbers in an IP address, or a number range in an IP address will be between 0 and 255, inclusive.
-
Each port or number in a port range will be between 1 and 65535 inclusive.
-
In any <NUMBER_RANGE> with two numbers, <LOWER_LIMIT> will be less than or equal to <UPPER_LIMIT>.
Examples
0)


{"FORWARD 192.168.000.* 001-100 192.168.0.10",
"FORWARD 192.168.0.1 80 10.10.95.184 8080",
"ACCEPT 192.168.*.* 25",
"REJECT 192.168.5.38 *"}
{"192.168.0.43 80",
"00192.00168.000.001 00080",
"192.168.0.1 110",
"192.168.1.73 80",
"192.168.1.73 25",
"206.26.210.5 53",
"192.168.5.38 25"
}
Returns:
{ "192.168.0.10:80",
"10.10.95.184:8080",
"REJECT",
"REJECT",
"ACCEPT",
"REJECT",
"REJECT" }
Packet 0 matches rule 0, and gets forwarded according to that rule. Packet 1 matches both rules 0 and 1, so rule 1 is applied. Packets 2, 3, and 5 don't match any rules, so they are rejected. Packet 4 matches rule 2, and is therefore accepted. Packet 6 matches rules 2 and 3, so it gets rejected (rule 3 is applied).

1)

{"FORWARD *.*.*.* * 192.168.0.1"}
{"213.148.161.82 9484",
"172.230.108.145 16627",
"122.141.122.130 46874",
"241.145.145.77 26390",
"139.97.106.125 35305",
"244.131.151.77 26390"}
Returns:
{ "192.168.0.1:9484",
"192.168.0.1:16627",
"192.168.0.1:46874",
"192.168.0.1:26390",
"192.168.0.1:35305",
"192.168.0.1:26390" }

2)

{"REJECT *.20-252.114-157.36-91 13171-54085",
"ACCEPT *.*.73-180.* *",
"FORWARD 55.63.173.239 * 168.154.33.25",
"REJECT *.72-73.*.48-191 *",
"REJECT 20.51.*.* 4579",
"ACCEPT 70-166.*.*.86-182 *",
"REJECT 88-190.*.119-157.* 3316-27844",
"FORWARD *.52-221.134-250.66-207 * 116.94.120.82"}
{"203.11.104.45 44072",
"154.92.128.87 30085",
"20.51.68.55 4579",
"177.73.138.69 14319",
"112.65.145.82 26287",
"55.63.173.239 45899"}
Returns:
{ "ACCEPT",
"ACCEPT",
"REJECT",
"116.94.120.82:14319",
"116.94.120.82:26287",
"168.154.33.25:45899" }
<think> 我们正在解决一个关于Ceres Solver库的编译问题。用户遇到了错误:使用 `ceres::Problem problem;` 时报告“不允许使用不完整的类型”。根据引用内容,我们了解到这可能与链接库的设置有关。 引用[1]提到链接时名称没有写对导致了一系列未定义引用错误,包括`ceres::Problem::Problem()`等。引用[3]提到在CMake中,没有正确使用`target_link_libraries`可能导致某些文件中无法正确使用Ceres类。 用户当前的错误是“不允许使用不完整的类型”,这通常发生在编译器知道有某个类型(通过头文件声明),但没有该类型的完整定义(通常是因为没有链接到库的实现)。在Ceres Solver的上下文中,这很可能是因为没有正确链接Ceres库。 解决方案步骤: 1. 确保CMakeLists.txt中正确引入了Ceres库,并且使用了`find_package(Ceres REQUIRED)`。 2. 确保在定义可执行文件或库时,使用`target_link_libraries`将Ceres库链接到目标。 例如,在CMakeLists.txt中: ```cmake find_package(Ceres REQUIRED) add_executable(my_program my_source.cpp) target_link_libraries(my_program Ceres::ceres) ``` 3. 如果项目中有多个目标(比如多个可执行文件或库),确保每个使用到Ceres库的目标都链接了Ceres库。 另外,引用[2]提到动态库加载问题(运行时找不到libgflags.so.2.2),这虽然与编译时问题不同,但提醒我们要确保所有依赖库在运行时可用。不过用户当前的问题发生在编译阶段(不完整类型),所以先解决编译链接问题。 如果按照上述步骤修改后问题仍然存在,可以尝试重新构建项目并确保CMake配置正确。 因此,解决用户问题的方法是:检查CMakeLists.txt,确保正确找到Ceres库并正确链接到目标。 根据上述分析,给出回答。 </think> ### 解决 `ceres::Problem problem;` 报错的方法 该错误通常是由于编译器无法识别 `ceres::Problem` 的完整定义导致的。以下是系统性的解决方法: #### 1. **检查头文件包含** 确保在源文件中**完整包含** Ceres 的头文件: ```cpp #include <ceres/ceres.h> // 必须包含完整头文件 ``` ✘ 错误示例:仅包含部分头文件(如 `#include <ceres/problem.h>`)可能导致类型不完整[^3]。 #### 2. **验证 CMake 链接配置** 在 `CMakeLists.txt` 中需正确链接 Ceres: ```cmake find_package(Ceres REQUIRED) add_executable(your_target your_source.cpp) target_link_libraries(your_target Ceres::ceres) # 必须精确使用此命名空间 ``` ⚠️ 关键细节: - 链接目标必须使用 `Ceres::ceres` 而非简单的 `ceres`[^1] - 确保每个使用 Ceres 的 `add_executable` 目标都单独链接[^3] #### 3. **检查依赖库完整性** 若报错涉及 `libgflags` 等依赖项缺失: ```bash # 安装完整依赖 sudo apt-get install libgflags-dev libgoogle-glog-dev libsuitesparse-dev # 更新动态库缓存 sudo ldconfig ``` 运行时错误 `libgflags.so.2.2 not found` 通常需重装兼容版本依赖库[^2]。 #### 4. **验证安装完整性** 重建 Ceres 以确保安装正确: ```bash mkdir build && cd build cmake .. -DBUILD_TESTING=OFF # 禁用测试加快编译 make -j8 sudo make install ``` #### 5. **代码结构检查** 若项目包含多个源文件: - 所有使用 Ceres 的文件都需包含 `<ceres/ceres.h>` - 避免前置声明 `ceres::Problem`(会触发不完整类型错误) > **故障排除流程图**: > 头文件包含 → CMake 链接目标 → 依赖库安装 → Ceres 重装 → 代码结构
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