#!/usr/bin/env python

from mininet.net import Mininet
from mininet.node import Controller, RemoteController, OVSController
from mininet.node import CPULimitedHost, Host, Node
from mininet.node import OVSKernelSwitch, UserSwitch
from mininet.node import IVSSwitch
from mininet.cli import CLI
from mininet.log import setLogLevel, info
from mininet.link import TCLink, Intf
from subprocess import call

def myNetwork():

    net = Mininet( topo=None,
                   build=False,
                   ipBase='192.168.0.100/24')

    info( '*** Adding controller\n' )
    c0=net.addController(name='c0',
                      controller=Controller,
                      protocol='tcp',
                      port=6633)

    info( '*** Add switches\n')
    s1 = net.addSwitch('s1', cls=OVSKernelSwitch)
    s2 = net.addSwitch('s2', cls=OVSKernelSwitch)

    info( '*** Add hosts\n')
    h1 = net.addHost('h1', cls=Host, ip='192.168.0.101/24', defaultRoute=None)
    h2 = net.addHost('h2', cls=Host, ip='192.168.0.102/24', defaultRoute=None)
    h3 = net.addHost('h3', cls=Host, ip='192.168.0.103/24', defaultRoute=None)
    h4 = net.addHost('h4', cls=Host, ip='192.168.0.104/24', defaultRoute=None)

    info( '*** Add links\n')
    net.addLink(h1, s1, 1, 1)
    net.addLink(s1, h2, 2, 1)
    net.addLink(s1, s2, 3, 3)
    net.addLink(s2, h3, 1, 1)
    net.addLink(s2, h4, 2, 1)

    info( '*** Starting network\n')
    net.build()
    info( '*** Starting controllers\n')
    for controller in net.controllers:
        controller.start()

    info( '*** Starting switches\n')
    net.get('s1').start([c0])
    net.get('s2').start([c0])
    
    CLI(net)
    net.stop()

if __name__ == '__main__':
    setLogLevel( 'info' )
    myNetwork()

struct ofp_header {
    uint8_t version;    /* OFP_VERSION. */
    uint8_t type;       /* One of the OFPT_ constants. */
    uint16_t length;    /* Length including this ofp_header. */
    uint32_t xid;       /* Transaction id associated with this packet.
                           Replies use the same id as was in the request
                           to facilitate pairing. */
};
OFP_ASSERT(sizeof(struct ofp_header) == 8);

/* OFPT_HELLO.  This message has an empty body, but implementations must
 * ignore any data included in the body, to allow for future extensions. */
struct ofp_hello {
    struct ofp_header header;
};

struct ofp_phy_port {
    uint16_t port_no;
    uint8_t hw_addr[OFP_ETH_ALEN];
    char name[OFP_MAX_PORT_NAME_LEN]; /* Null-terminated */

    uint32_t config;        /* Bitmap of OFPPC_* flags. */
    uint32_t state;         /* Bitmap of OFPPS_* flags. */

    /* Bitmaps of OFPPF_* that describe features.  All bits zeroed if
     * unsupported or unavailable. */
    uint32_t curr;          /* Current features. */
    uint32_t advertised;    /* Features being advertised by the port. */
    uint32_t supported;     /* Features supported by the port. */
    uint32_t peer;          /* Features advertised by peer. */
};
    
    struct ofp_switch_features {
    struct ofp_header header;
    uint64_t datapath_id;   /* Datapath unique ID.  The lower 48-bits are for
                               a MAC address, while the upper 16-bits are
                               implementer-defined. */
                            /*唯一标识 id 号*/
    uint32_t n_buffers;     /* Max packets buffered at once. */ /*交缓冲区可以缓存的最大数据包个数*/
                            
    uint8_t n_tables;       /* Number of tables supported by datapath. */ /*流表数量*/
                          
    uint8_t pad[3];         /* Align to 64-bits. */ /*填充值*/
                            
    /* Features. */
    uint32_t capabilities;  /* Bitmap of support "ofp_capabilities". */ /*支持的特殊功能*/
    uint32_t actions;       /* Bitmap of supported "ofp_action_type"s. */ /*支持的动作*/

    /* Port info.*/
    struct ofp_phy_port ports[0];  /* Port definitions.  The number of ports
                                      is inferred from the length field in
                                      the header. */ /*物理端口描述列表*/
};

struct ofp_switch_config {
    struct ofp_header header;
    uint16_t flags;             /* OFPC_* flags. */ /*指示交换机如何才处理 IP 分片数据包*/
    uint16_t miss_send_len;     /* Max bytes of new flow that datapath should
                                   send to the controller. */ /*指示当一个交换机无法处理的数据包到达时，将数据包发给控制器的最大字节数*/
};
enum ofp_config_flags {
    /* Handling of IP fragments. */
    OFPC_FRAG_NORMAL   = 0,  /* No special handling for fragments. */
    OFPC_FRAG_DROP     = 1,  /* Drop fragments. */
    OFPC_FRAG_REASM    = 2,  /* Reassemble (only if OFPC_IP_REASM set). */
    OFPC_FRAG_MASK     = 3
};

struct ofp_port_status {
    struct ofp_header header;
    uint8_t reason;          /* One of OFPPR_*. */
    uint8_t pad[7];          /* Align to 64-bits. */
    struct ofp_phy_port desc;
};

struct ofp_packet_in {
    struct ofp_header header;
    uint32_t buffer_id;     /* ID assigned by datapath. */ /*Packet-in消息所携带的数据包在交换机缓存区中的ID*/
    uint16_t total_len;     /* Full length of frame. */ /*data字段的长度*/
    uint16_t in_port;       /* Port on which frame was received. */ /*数据包进入交换机时的端口号*/
    uint8_t reason;         /* Reason packet is being sent (one of OFPR_*) */ /*发送Packet-in消息的原因*/
    uint8_t pad;
    uint8_t data[0];        /* Ethernet frame, halfway through 32-bit word,
                               so the IP header is 32-bit aligned.  The
                               amount of data is inferred from the length
                               field in the header.  Because of padding,
                               offsetof(struct ofp_packet_in, data) ==
                               sizeof(struct ofp_packet_in) - 2. */ /*携带的数据包*/
};
enum ofp_packet_in_reason {
    OFPR_NO_MATCH,          /* No matching flow. */ /*没有匹配的条目*/
    OFPR_ACTION             /* Action explicitly output to controller. */ /*action列表中包含转发给控制器的动作*/
};

struct ofp_packet_out {
  struct ofp_header header;
  uint32_t buffer_id;           /* ID assigned by datapath (-1 if none). */ /*交换机缓存区id*/
  uint16_t in_port;             /* Packet's input port (OFPP_NONE if none). */
  uint16_t actions_len;         /* Size of action array in bytes. */ /*action列表的长度*/
  struct ofp_action_header actions[0]; /* Actions. */ /*动作列表*/
  /* uint8_t data[0]; */        /* Packet data.  The length is inferred
                                   from the length field in the header.
                                   (Only meaningful if buffer_id == -1.) */
};
struct ofp_action_header {
  uint16_t type;                  /* One of OFPAT_*. */
  uint16_t len;                   /* Length of action, including this
                                     header.  This is the length of action,
                                     including any padding to make it
                                     64-bit aligned. */
  uint8_t pad[4];
};

enum ofp_flow_mod_command /*Flow-Mod 消息共有五种类型*/
 {
    OFPFC_ADD,              /* New flow. */
    OFPFC_MODIFY,           /* Modify all matching flows. */
    OFPFC_MODIFY_STRICT,    /* Modify entry strictly matching wildcards */
    OFPFC_DELETE,           /* Delete all matching flows. */
    OFPFC_DELETE_STRICT    /* Strictly match wildcards and priority. */
};
struct ofp_flow_mod {
    struct ofp_header header;
    struct ofp_match match;      /* Fields to match */ /*流表的匹配域*/
    uint64_t cookie;             /* Opaque controller-issued identifier. */ /*流表项标识符*/

    /* Flow actions. */
    uint16_t command;             /* One of OFPFC_*. */
    uint16_t idle_timeout;        /* Idle time before discarding (seconds). */ /*空闲超时时间*/
    uint16_t hard_timeout;        /* Max time before discarding (seconds). */  /*最大生存时间*/
    uint16_t priority;            /* Priority level of flow entry. */ /*优先级，优先级高的流表项优先匹配*/
    uint32_t buffer_id;           /* Buffered packet to apply to (or -1). 
                                     Not meaningful for OFPFC_DELETE*. */ /*缓存区ID*/
    uint16_t out_port;            /* For OFPFC_DELETE* commands, require
                                     matching entries to include this as an
                                     output port.  A value of OFPP_NONE
                                     indicates no restriction. */
    uint16_t flags;               /* One of OFPFF_*. */
    struct ofp_action_header actions[0]; /* The action length is inferred
                                            from the length field in the
                                            header. */ /*action列表*/
};