Openvswitch原理与代码分析(8): 修改Openvswitch代码添加自定义action

有时候我们需要自定义一些自己的action，根据包头里面的信息，做一些自己的操作。

 

例如添加一个action名为handle_example

 

第一、修改ofp-actions.c文件

 

首先在ofp-actions.c里面添加Openflow各个版本的这个action

1. static
   const
   struct ofpact_map *
2. get_ofpact_map(enum ofp_version version)
3. {
4.     /* OpenFlow 1.0 actions. */
5.     static
   const
   struct ofpact_map of10[] = {
6.         { OFPACT_OUTPUT, 0 },
7.         { OFPACT_SET_VLAN_VID, 1 },
8.         { OFPACT_SET_VLAN_PCP, 2 },
9.         { OFPACT_STRIP_VLAN, 3 },
10.         { OFPACT_SET_ETH_SRC, 4 },
11.         { OFPACT_SET_ETH_DST, 5 },
12.         { OFPACT_SET_IPV4_SRC, 6 },
13.         { OFPACT_SET_IPV4_DST, 7 },
14.         { OFPACT_SET_IP_DSCP, 8 },
15.         { OFPACT_SET_L4_SRC_PORT, 9 },
16.         { OFPACT_SET_L4_DST_PORT, 10 },
17.         { OFPACT_ENQUEUE, 11 },
18.         { OFPACT_HANDLE_EXAMPLE, 28 },
19.         { 0, -1 },
20.     };
21.  
22.     /* OpenFlow 1.1 actions. */
23.     static
    const
    struct ofpact_map of11[] = {
24.         { OFPACT_OUTPUT, 0 },
25.         { OFPACT_SET_VLAN_VID, 1 },
26.         { OFPACT_SET_VLAN_PCP, 2 },
27.         { OFPACT_SET_ETH_SRC, 3 },
28.         { OFPACT_SET_ETH_DST, 4 },
29.         { OFPACT_SET_IPV4_SRC, 5 },
30.         { OFPACT_SET_IPV4_DST, 6 },
31.         { OFPACT_SET_IP_DSCP, 7 },
32.         { OFPACT_SET_IP_ECN, 8 },
33.         { OFPACT_SET_L4_SRC_PORT, 9 },
34.         { OFPACT_SET_L4_DST_PORT, 10 },
35.         /* OFPAT_COPY_TTL_OUT (11) not supported. */
36.         /* OFPAT_COPY_TTL_IN (12) not supported. */
37.         { OFPACT_SET_MPLS_LABEL, 13 },
38.         { OFPACT_SET_MPLS_TC, 14 },
39.         { OFPACT_SET_MPLS_TTL, 15 },
40.         { OFPACT_DEC_MPLS_TTL, 16 },
41.         { OFPACT_PUSH_VLAN, 17 },
42.         { OFPACT_STRIP_VLAN, 18 },
43.         { OFPACT_PUSH_MPLS, 19 },
44.         { OFPACT_POP_MPLS, 20 },
45.         { OFPACT_SET_QUEUE, 21 },
46.         { OFPACT_GROUP, 22 },
47.         { OFPACT_SET_IP_TTL, 23 },
48.         { OFPACT_DEC_TTL, 24 },
49.         { OFPACT_HANDLE_EXAMPLE, 28 },
50.         { 0, -1 },
51.     };
52.  
53.     /* OpenFlow 1.2, 1.3, and 1.4 actions. */
54.     static
    const
    struct ofpact_map of12[] = {
55.         { OFPACT_OUTPUT, 0 },
56.         /* OFPAT_COPY_TTL_OUT (11) not supported. */
57.         /* OFPAT_COPY_TTL_IN (12) not supported. */
58.         { OFPACT_SET_MPLS_TTL, 15 },
59.         { OFPACT_DEC_MPLS_TTL, 16 },
60.         { OFPACT_PUSH_VLAN, 17 },
61.         { OFPACT_STRIP_VLAN, 18 },
62.         { OFPACT_PUSH_MPLS, 19 },
63.         { OFPACT_POP_MPLS, 20 },
64.         { OFPACT_SET_QUEUE, 21 },
65.         { OFPACT_GROUP, 22 },
66.         { OFPACT_SET_IP_TTL, 23 },
67.         { OFPACT_DEC_TTL, 24 },
68.         { OFPACT_SET_FIELD, 25 },
69.         /* OF1.3+ OFPAT_PUSH_PBB (26) not supported. */
70.         /* OF1.3+ OFPAT_POP_PBB (27) not supported. */
71.         { OFPACT_HANDLE_EXAMPLE, 28 },
72.         { 0, -1 },
73.     };
74.  
75.     switch (version) {
76.     case OFP10_VERSION:
77.         return of10;
78.  
79.     case OFP11_VERSION:
80.         return of11;
81.  
82.     case OFP12_VERSION:
83.     case OFP13_VERSION:
84.     case OFP14_VERSION:
85.     case OFP15_VERSION:
86.     default:
87.         return of12;
88.     }
89. }

 

其次添加raw action type

1. enum ofp_raw_action_type {
2. /* ## ----------------- ## */
3. /* ## Standard actions. ## */
4. /* ## ----------------- ## */
5.  
6.     /* OF1.0(0): struct ofp10_action_output. */
7.     OFPAT_RAW10_OUTPUT,
8.     /* OF1.1+(0): struct ofp11_action_output. */
9.     OFPAT_RAW11_OUTPUT,
10.  
11.     /* OF1.0(1): uint16_t. */
12.     OFPAT_RAW10_SET_VLAN_VID,
13.     /* OF1.0(2): uint8_t. */
14.     OFPAT_RAW10_SET_VLAN_PCP,
15.  
16.     /* OF1.1(1), OF1.2+(1) is deprecated (use Set-Field): uint16_t.
17.      *
18.      * [Semantics differ slightly between the 1.0 and 1.1 versions of the VLAN
19.      * modification actions: the 1.0 versions push a VLAN header if none is
20.      * present, but the 1.1 versions do not. That is the only reason that we
21.      * distinguish their raw action types.] */
22.     OFPAT_RAW11_SET_VLAN_VID,
23.     /* OF1.1(2), OF1.2+(2) is deprecated (use Set-Field): uint8_t. */
24.     OFPAT_RAW11_SET_VLAN_PCP,
25.  
26.     /* OF1.1+(17): ovs_be16.
27.      *
28.      * [The argument is the Ethertype, e.g. ETH_TYPE_VLAN_8021Q, not the VID or
29.      * TCI.] */
30.     OFPAT_RAW11_PUSH_VLAN,
31.  
32.     /* OF1.0(3): void. */
33.     OFPAT_RAW10_STRIP_VLAN,
34.     /* OF1.1+(18): void. */
35.     OFPAT_RAW11_POP_VLAN,
36.  
37.     /* OF1.0(4), OF1.1(3), OF1.2+(3) is deprecated (use Set-Field): struct
38.      * ofp_action_dl_addr. */
39.     OFPAT_RAW_SET_DL_SRC,
40.  
41.     /* OF1.0(5), OF1.1(4), OF1.2+(4) is deprecated (use Set-Field): struct
42.      * ofp_action_dl_addr. */
43.     OFPAT_RAW_SET_DL_DST,
44.  
45.     /* OF1.0(6), OF1.1(5), OF1.2+(5) is deprecated (use Set-Field):
46.      * ovs_be32. */
47.     OFPAT_RAW_SET_NW_SRC,
48.  
49.     /* OF1.0(7), OF1.1(6), OF1.2+(6) is deprecated (use Set-Field):
50.      * ovs_be32. */
51.     OFPAT_RAW_SET_NW_DST,
52.  
53.     /* OF1.0(8), OF1.1(7), OF1.2+(7) is deprecated (use Set-Field): uint8_t. */
54.     OFPAT_RAW_SET_NW_TOS,
55.  
56.     /* OF1.1(8), OF1.2+(8) is deprecated (use Set-Field): uint8_t. */
57.     OFPAT_RAW11_SET_NW_ECN,
58.  
59.     /* OF1.0(9), OF1.1(9), OF1.2+(9) is deprecated (use Set-Field):
60.      * ovs_be16. */
61.     OFPAT_RAW_SET_TP_SRC,
62.  
63.     /* OF1.0(10), OF1.1(10), OF1.2+(10) is deprecated (use Set-Field):
64.      * ovs_be16. */
65.     OFPAT_RAW_SET_TP_DST,
66.  
67.     /* OF1.0(11): struct ofp10_action_enqueue. */
68.     OFPAT_RAW10_ENQUEUE,
69.  
70.     /* NX1.0(30), OF1.1(13), OF1.2+(13) is deprecated (use Set-Field):
71.      * ovs_be32. */
72.     OFPAT_RAW_SET_MPLS_LABEL,
73.  
74.     /* NX1.0(31), OF1.1(14), OF1.2+(14) is deprecated (use Set-Field):
75.      * uint8_t. */
76.     OFPAT_RAW_SET_MPLS_TC,
77.  
78.     /* NX1.0(25), OF1.1(15), OF1.2+(15) is deprecated (use Set-Field):
79.      * uint8_t. */
80.     OFPAT_RAW_SET_MPLS_TTL,
81.  
82.     /* NX1.0(26), OF1.1+(16): void. */
83.     OFPAT_RAW_DEC_MPLS_TTL,
84.  
85.     /* NX1.0(23), OF1.1+(19): ovs_be16.
86.      *
87.      * [The argument is the Ethertype, e.g. ETH_TYPE_MPLS, not the label.] */
88.     OFPAT_RAW_PUSH_MPLS,
89.  
90.     /* NX1.0(24), OF1.1+(20): ovs_be16.
91.      *
92.      * [The argument is the Ethertype, e.g. ETH_TYPE_IPV4 if at BoS or
93.      * ETH_TYPE_MPLS otherwise, not the label.] */
94.     OFPAT_RAW_POP_MPLS,
95.  
96.     /* NX1.0(4), OF1.1+(21): uint32_t. */
97.     OFPAT_RAW_SET_QUEUE,
98.  
99.     /* OF1.1+(22): uint32_t. */
100.     OFPAT_RAW11_GROUP,
101.  
102.     /* OF1.1+(23): uint8_t. */
103.     OFPAT_RAW11_SET_NW_TTL,
104.  
105.     /* NX1.0(18), OF1.1+(24): void. */
106.     OFPAT_RAW_DEC_NW_TTL,
107.     /* NX1.0+(21): struct nx_action_cnt_ids, ... */
108.     NXAST_RAW_DEC_TTL_CNT_IDS,
109.  
110.     /* OF1.2-1.4(25): struct ofp12_action_set_field, ... */
111.     OFPAT_RAW12_SET_FIELD,
112.     /* OF1.5+(25): struct ofp12_action_set_field, ... */
113.     OFPAT_RAW15_SET_FIELD,
114.  
115.     /* OF1.0(28): void. */
116.     OFPAT_RAW10_HANDLE_EXAMPLE,
117.  
118.     /* OF1.1(28): void. */
119.     OFPAT_RAW11_HANDLE_EXAMPLE,
120.  
121.     /* OF1.2-1.4(28): void. */
122.     OFPAT_RAW12_HANDLE_EXAMPLE,
123.  
124.     /* NX1.0-1.4(7): struct nx_action_reg_load.
125.      *
126.      * [In OpenFlow 1.5, set_field is a superset of reg_load functionality, so
127.      * we drop reg_load.] */
128.     NXAST_RAW_REG_LOAD,
129.     /* NX1.0-1.4(33): struct nx_action_reg_load2, ...
130.      *
131.      * [In OpenFlow 1.5, set_field is a superset of reg_load2 functionality, so
132.      * we drop reg_load2.] */
133.     NXAST_RAW_REG_LOAD2,
134.  
135.     /* OF1.5+(28): struct ofp15_action_copy_field, ... */
136.     OFPAT_RAW15_COPY_FIELD,
137.     /* ONF1.3-1.4(3200): struct onf_action_copy_field, ... */
138.     ONFACT_RAW13_COPY_FIELD,
139.     /* NX1.0-1.4(6): struct nx_action_reg_move, ... */
140.     NXAST_RAW_REG_MOVE,
141.  
142. /* ## ------------------------- ## */
143. /* ## Nicira extension actions. ## */
144. /* ## ------------------------- ## */
145.  
146. /* Actions similar to standard actions are listed with the standard actions. */
147.  
148.     /* NX1.0+(1): uint16_t. */
149.     NXAST_RAW_RESUBMIT,
150.     /* NX1.0+(14): struct nx_action_resubmit. */
151.     NXAST_RAW_RESUBMIT_TABLE,
152.  
153.     /* NX1.0+(2): uint32_t. */
154.     NXAST_RAW_SET_TUNNEL,
155.     /* NX1.0+(9): uint64_t. */
156.     NXAST_RAW_SET_TUNNEL64,
157.  
158.     /* NX1.0+(5): void. */
159.     NXAST_RAW_POP_QUEUE,
160.  
161.     /* NX1.0+(8): struct nx_action_note, ... */
162.     NXAST_RAW_NOTE,
163.  
164.     /* NX1.0+(10): struct nx_action_multipath. */
165.     NXAST_RAW_MULTIPATH,
166.  
167.     /* NX1.0+(12): struct nx_action_bundle, ... */
168.     NXAST_RAW_BUNDLE,
169.     /* NX1.0+(13): struct nx_action_bundle, ... */
170.     NXAST_RAW_BUNDLE_LOAD,
171.  
172.     /* NX1.0+(15): struct nx_action_output_reg. */
173.     NXAST_RAW_OUTPUT_REG,
174.     /* NX1.0+(32): struct nx_action_output_reg2. */
175.     NXAST_RAW_OUTPUT_REG2,
176.  
177.     /* NX1.0+(16): struct nx_action_learn, ... */
178.     NXAST_RAW_LEARN,
179.  
180.     /* NX1.0+(17): void. */
181.     NXAST_RAW_EXIT,
182.  
183.     /* NX1.0+(19): struct nx_action_fin_timeout. */
184.     NXAST_RAW_FIN_TIMEOUT,
185.  
186.     /* NX1.0+(20): struct nx_action_controller. */
187.     NXAST_RAW_CONTROLLER,
188.  
189.     /* NX1.0+(22): struct nx_action_write_metadata. */
190.     NXAST_RAW_WRITE_METADATA,
191.  
192.     /* NX1.0+(27): struct nx_action_stack. */
193.     NXAST_RAW_STACK_PUSH,
194.  
195.     /* NX1.0+(28): struct nx_action_stack. */
196.     NXAST_RAW_STACK_POP,
197.  
198.     /* NX1.0+(29): struct nx_action_sample. */
199.     NXAST_RAW_SAMPLE,
200.  
201.     /* NX1.0+(34): struct nx_action_conjunction. */
202.     NXAST_RAW_CONJUNCTION,
203.  
204.     /* NX1.0+(35): struct nx_action_conntrack, ... */
205.     NXAST_RAW_CT,
206.  
207. /* ## ------------------ ## */
208. /* ## Debugging actions. ## */
209. /* ## ------------------ ## */
210.  
211. /* These are intentionally undocumented, subject to change, and ovs-vswitchd */
212. /* accepts them only if started with --enable-dummy. */
213.  
214.     /* NX1.0+(255): void. */
215.     NXAST_RAW_DEBUG_RECIRC,
216. };

 

第三，添加handle example的action的处理函数

1. /* handle gtp actions. */
2. static
   enum ofperr
3. decode_OFPAT_RAW10_HANDLE_EXAMPLE(struct ofpbuf *out)
4. {
5.     ofpact_put_HANDLE_EXAMPLE(out)->ofpact.raw = OFPAT_RAW10_HANDLE_EXAMPLE;
6.     return 0;
7. }
8.  
9. static
   enum ofperr
10. decode_OFPAT_RAW11_HANDLE_EXAMPLE(struct ofpbuf *out)
11. {
12.     ofpact_put_HANDLE_EXAMPLE(out)->ofpact.raw = OFPAT_RAW11_HANDLE_EXAMPLE;
13.     return 0;
14. }
15.  
16. static
    enum ofperr
17. decode_OFPAT_RAW12_HANDLE_EXAMPLE(struct ofpbuf *out)
18. {
19.     ofpact_put_HANDLE_EXAMPLE(out)->ofpact.raw = OFPAT_RAW12_HANDLE_EXAMPLE;
20.     return 0;
21. }
22.  
23. static
    void
24. encode_HANDLE_EXAMPLE(const
    struct ofpact_null *null OVS_UNUSED,
25.                   enum ofp_version ofp_version, struct ofpbuf *out)
26. {
27.     if (ofp_version == OFP10_VERSION) {
28.         put_OFPAT10_HANDLE_EXAMPLE(out);
29.     } else
    if (ofp_version == OFP11_VERSION) {
30.         put_OFPAT11_HANDLE_EXAMPLE(out);
31.     } else {
32.         put_OFPAT12_HANDLE_EXAMPLE(out);
33.     }
34. }
35.  
36. static
    char * OVS_WARN_UNUSED_RESULT
37. parse_HANDLE_EXAMPLE(char *arg OVS_UNUSED, struct ofpbuf *ofpacts,
38.                  enum ofputil_protocol *usable_protocols OVS_UNUSED)
39. {
40.     ofpact_put_HANDLE_EXAMPLE(ofpacts)->ofpact.raw = OFPAT_RAW10_HANDLE_EXAMPLE;
41.     return NULL;
42. }
43.  
44. static
    void
45. format_HANDLE_EXAMPLE(const
    struct ofpact_null *a OVS_UNUSED, struct ds *s)
46. {
47.     ds_put_cstr(s, "handle_example");
48. }

 

1. struct ofpact *
2. ofpact_next_flattened(const
   struct ofpact *ofpact)
3. {
4. switch (ofpact->type) {
5. case OFPACT_HANDLE_EXAMPLE:

 

1. static
   bool
2. ofpact_is_set_or_move_action(const
   struct ofpact *a)
3. {
4.     switch (a->type) {
5.     case OFPACT_HANDLE_EXAMPLE:
6. return true;

 

1. static
   bool
2. ofpact_is_allowed_in_actions_set(const
   struct ofpact *a)
3. {
4.     switch (a->type) {
5.     case OFPACT_HANDLE_EXAMPLE:
6. return true;

 

1. enum ovs_instruction_type
2. ovs_instruction_type_from_ofpact_type(enum ofpact_type type)
3. {
4.     switch (type) {
5.     case OFPACT_HANDLE_EXAMPLE:

 

1. static
   enum ofperr
2. ofpact_check__(enum ofputil_protocol *usable_protocols, struct ofpact *a,
3.                struct flow *flow, ofp_port_t max_ports,
4.                uint8_t table_id, uint8_t n_tables)
5. {
6.     const
   struct ofpact_enqueue *enqueue;
7.     const
   struct mf_field *mf;
8.  
9.     switch (a->type) {
10.     case OFPACT_HANDLE_EXAMPLE:
11.         return 0;

 

1. static
   bool
2. ofpact_outputs_to_port(const
   struct ofpact *ofpact, ofp_port_t port)
3. {
4.     switch (ofpact->type) {
5.     case OFPACT_HANDLE_EXAMPLE:
6.     default:
7.         return
   false;

 

第二，修改文件ofp-actions.h

 

1. #define OFPACTS \
2.     /* Output. */ \
3.     OFPACT(OUTPUT, ofpact_output, ofpact, "output") \
4.     OFPACT(GROUP, ofpact_group, ofpact, "group") \
5.     OFPACT(CONTROLLER, ofpact_controller, ofpact, "controller") \
6.     OFPACT(ENQUEUE, ofpact_enqueue, ofpact, "enqueue") \
7.     OFPACT(OUTPUT_REG, ofpact_output_reg, ofpact, "output_reg") \
8.     OFPACT(BUNDLE, ofpact_bundle, slaves, "bundle") \
9.                                                                         \
10.     /* Header changes. */ \
11.     OFPACT(SET_FIELD, ofpact_set_field, ofpact, "set_field") \
12.     OFPACT(HANDLE_EXAMPLE, ofpact_null, ofpact, "handle_example") \
13.     OFPACT(SET_VLAN_VID, ofpact_vlan_vid, ofpact, "set_vlan_vid") \
14.     OFPACT(SET_VLAN_PCP, ofpact_vlan_pcp, ofpact, "set_vlan_pcp") \
15.     OFPACT(STRIP_VLAN, ofpact_null, ofpact, "strip_vlan") \
16.     OFPACT(PUSH_VLAN, ofpact_null, ofpact, "push_vlan") \
17.     OFPACT(SET_ETH_SRC, ofpact_mac, ofpact, "mod_dl_src") \
18.     OFPACT(SET_ETH_DST, ofpact_mac, ofpact, "mod_dl_dst") \
19.     OFPACT(SET_IPV4_SRC, ofpact_ipv4, ofpact, "mod_nw_src") \
20.     OFPACT(SET_IPV4_DST, ofpact_ipv4, ofpact, "mod_nw_dst") \
21.     OFPACT(SET_IP_DSCP, ofpact_dscp, ofpact, "mod_nw_tos") \
22.     OFPACT(SET_IP_ECN, ofpact_ecn, ofpact, "mod_nw_ecn") \
23.     OFPACT(SET_IP_TTL, ofpact_ip_ttl, ofpact, "mod_nw_ttl") \
24.     OFPACT(SET_L4_SRC_PORT, ofpact_l4_port, ofpact, "mod_tp_src") \
25.     OFPACT(SET_L4_DST_PORT, ofpact_l4_port, ofpact, "mod_tp_dst") \
26.     OFPACT(REG_MOVE, ofpact_reg_move, ofpact, "move") \
27.     OFPACT(STACK_PUSH, ofpact_stack, ofpact, "push") \
28.     OFPACT(STACK_POP, ofpact_stack, ofpact, "pop") \
29.     OFPACT(DEC_TTL, ofpact_cnt_ids, cnt_ids, "dec_ttl") \
30.     OFPACT(SET_MPLS_LABEL, ofpact_mpls_label, ofpact, "set_mpls_label") \
31.     OFPACT(SET_MPLS_TC, ofpact_mpls_tc, ofpact, "set_mpls_tc") \
32.     OFPACT(SET_MPLS_TTL, ofpact_mpls_ttl, ofpact, "set_mpls_ttl") \
33.     OFPACT(DEC_MPLS_TTL, ofpact_null, ofpact, "dec_mpls_ttl") \
34.     OFPACT(PUSH_MPLS, ofpact_push_mpls, ofpact, "push_mpls") \
35.     OFPACT(POP_MPLS, ofpact_pop_mpls, ofpact, "pop_mpls") \
36.                                                                         \
37.     /* Metadata. */ \
38.     OFPACT(SET_TUNNEL, ofpact_tunnel, ofpact, "set_tunnel") \
39.     OFPACT(SET_QUEUE, ofpact_queue, ofpact, "set_queue") \
40.     OFPACT(POP_QUEUE, ofpact_null, ofpact, "pop_queue") \
41.     OFPACT(FIN_TIMEOUT, ofpact_fin_timeout, ofpact, "fin_timeout") \
42.                                                                         \
43.     /* Flow table interaction. */ \
44.     OFPACT(RESUBMIT, ofpact_resubmit, ofpact, "resubmit") \
45.     OFPACT(LEARN, ofpact_learn, specs, "learn") \
46.     OFPACT(CONJUNCTION, ofpact_conjunction, ofpact, "conjunction") \
47.                                                                         \
48.     /* Arithmetic. */ \
49.     OFPACT(MULTIPATH, ofpact_multipath, ofpact, "multipath") \
50.                                                                         \
51.     /* Other. */ \
52.     OFPACT(NOTE, ofpact_note, data, "note") \
53.     OFPACT(EXIT, ofpact_null, ofpact, "exit") \
54.     OFPACT(SAMPLE, ofpact_sample, ofpact, "sample") \
55.     OFPACT(UNROLL_XLATE, ofpact_unroll_xlate, ofpact, "unroll_xlate") \
56.     OFPACT(CT, ofpact_conntrack, ofpact, "ct") \
57.                                                                         \
58.     /* Debugging actions. \
59.      * \
60.      * These are intentionally undocumented, subject to change, and \
61.      * only accepted if ovs-vswitchd is started with --enable-dummy. */ \
62.     OFPACT(DEBUG_RECIRC, ofpact_null, ofpact, "debug_recirc") \
63.                                                                         \
64.     /* Instructions. */ \
65.     OFPACT(METER, ofpact_meter, ofpact, "meter") \
66.     OFPACT(CLEAR_ACTIONS, ofpact_null, ofpact, "clear_actions") \
67.     OFPACT(WRITE_ACTIONS, ofpact_nest, ofpact, "write_actions") \
68.     OFPACT(WRITE_METADATA, ofpact_metadata, ofpact, "write_metadata") \
69.     OFPACT(GOTO_TABLE, ofpact_goto_table, ofpact, "goto_table")

 

第三、修改ofproto\ofproto-dpif-xlate.c文件

 

1. static
   void
2. recirc_unroll_actions(const
   struct ofpact *ofpacts, size_t ofpacts_len,
3.                       struct xlate_ctx *ctx)
4. {
5.     const
   struct ofpact *a;
6.  
7.     OFPACT_FOR_EACH (a, ofpacts, ofpacts_len) {
8.         switch (a->type) {
9.         case OFPACT_OPERATE_EXAMPLE:
10.             /* These may not generate PACKET INs. */
11.             break;

 

1. static
   void
2. do_xlate_actions(const
   struct ofpact *ofpacts, size_t ofpacts_len,
3.                  struct xlate_ctx *ctx)
4. {
5.     struct flow_wildcards *wc = ctx->wc;
6.     struct flow *flow = &ctx->xin->flow;
7.     const
   struct ofpact *a;
8.  
9.     if (ovs_native_tunneling_is_on(ctx->xbridge->ofproto)) {
10.         tnl_neigh_snoop(flow, wc, ctx->xbridge->name);
11.     }
12.     /* dl_type already in the mask, not set below. */
13.  
14.     OFPACT_FOR_EACH (a, ofpacts, ofpacts_len) {
15.         struct ofpact_controller *controller;
16.         const
    struct ofpact_metadata *metadata;
17.         const
    struct ofpact_set_field *set_field;
18.         const
    struct mf_field *mf;
19.  
20.         if (ctx->error) {
21.             break;
22.         }
23.  
24.         if (ctx->exit) {
25.             /* Check if need to store the remaining actions for later
26.              * execution. */
27.             if (exit_recirculates(ctx)) {
28.                 recirc_unroll_actions(a, OFPACT_ALIGN(ofpacts_len -
29.                                                       ((uint8_t *)a -
30.                                                        (uint8_t *)ofpacts)),
31.                                       ctx);
32.             }
33.             break;
34.         }
35.  
36.         switch (a->type) {
37.    case OFPACT_HANDLE_EXAMPLE:
38.             VLOG_INFO("OFPACT_HANDLE_EXAMPLE");
39.             CHECK_MPLS_RECIRCULATION();
40.             handle_example(flow, wc, ctx->xin->packet, ctx);
41.             break;

 

最最重要的就是handle_example的实现，为你自己实现的逻辑，对于包头的修改可以通过修改flow来进行，也可以进一步解析ctx->xin->packet，也即解析网络包的正文。