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SIP: Refactoring too many if-else branches by table-driven method 

When there are a lot of if-else branch judgments, the table-driven method can be used to optimize to facilitate subsequent maintenance.
The original function remain unchanged.
This commit is contained in:
easonweii 2022-05-10 11:00:26 +08:00 committed by Gerald Combs
parent 7b749f5e15
commit eedf82cd97
1 changed files with 53 additions and 75 deletions
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128
epan/dissectors/packet-sip.c
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@ -791,6 +791,31 @@ static header_parameter_t via_parameters_hf_array[] =
{"oc-algo", &hf_sip_via_oc_algo}
};
typedef enum {
MECH_PARA_STRING = 0,
MECH_PARA_UINT = 1,
} mech_parameter_type_t;
/* Track associations between parameter name and hf item for security mechanism*/
typedef struct {
const char *param_name;
const gint para_type;
const gint *hf_item;
} mech_parameter_t;
static mech_parameter_t sec_mechanism_parameters_hf_array[] =
{
{"alg", MECH_PARA_STRING, &hf_sip_sec_mechanism_alg},
{"ealg", MECH_PARA_STRING, &hf_sip_sec_mechanism_ealg},
{"prot", MECH_PARA_STRING, &hf_sip_sec_mechanism_prot},
{"spi-c", MECH_PARA_UINT, &hf_sip_sec_mechanism_spi_c},
{"spi-s", MECH_PARA_UINT, &hf_sip_sec_mechanism_spi_s},
{"port1", MECH_PARA_UINT, &hf_sip_sec_mechanism_port1},
{"port-c", MECH_PARA_UINT, &hf_sip_sec_mechanism_port_c},
{"port2", MECH_PARA_UINT, &hf_sip_sec_mechanism_port2},
{"port-s", MECH_PARA_UINT, &hf_sip_sec_mechanism_port_s},
{NULL, 0, 0}
};
typedef struct {
gint *hf_sip_display;
@ -2408,9 +2433,6 @@ static void
dissect_sip_sec_mechanism(tvbuff_t *tvb, packet_info* pinfo, proto_tree *tree, gint start_offset, gint line_end_offset){
gint current_offset, semi_colon_offset, length, par_name_end_offset, equals_offset;
guint32 spi_c;
guint32 spi_s;
guint16 port;
/* skip Spaces and Tabs */
start_offset = tvb_skip_wsp(tvb, start_offset, line_end_offset - start_offset);
@ -2437,7 +2459,7 @@ dissect_sip_sec_mechanism(tvbuff_t *tvb, packet_info* pinfo, proto_tree *tree, g
while(current_offset < line_end_offset){
gchar *param_name = NULL, *value = NULL;
guint8 hf_index = 0;
/* skip Spaces and Tabs */
current_offset = tvb_skip_wsp(tvb, current_offset, line_end_offset - current_offset);
@ -2461,82 +2483,38 @@ dissect_sip_sec_mechanism(tvbuff_t *tvb, packet_info* pinfo, proto_tree *tree, g
}
/* Protection algorithm to be used */
if (g_ascii_strcasecmp(param_name, "alg") == 0){
proto_tree_add_item(tree, hf_sip_sec_mechanism_alg, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1,
ENC_UTF_8);
}else if (g_ascii_strcasecmp(param_name, "ealg") == 0){
proto_tree_add_item(tree, hf_sip_sec_mechanism_ealg, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1,
ENC_UTF_8);
}else if (g_ascii_strcasecmp(param_name, "prot") == 0){
proto_tree_add_item(tree, hf_sip_sec_mechanism_prot, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1,
ENC_UTF_8);
}else if (g_ascii_strcasecmp(param_name, "spi-c") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
spi_c = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_spi_c, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, spi_c);
}
}else if (g_ascii_strcasecmp(param_name, "spi-s") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
spi_s = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_spi_s, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, spi_s);
}
}else if (g_ascii_strcasecmp(param_name, "port1") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
port = (guint16)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_port1, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, port);
}
}else if (g_ascii_strcasecmp(param_name, "port-c") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
port = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_port_c, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, port);
}
}else if (g_ascii_strcasecmp(param_name, "port2") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
port = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_port2, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, port);
}
}else if (g_ascii_strcasecmp(param_name, "port-s") == 0){
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
port = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, hf_sip_sec_mechanism_port_s, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, port);
while (sec_mechanism_parameters_hf_array[hf_index].param_name) {
/* Protection algorithm to be used */
if (g_ascii_strcasecmp(param_name, sec_mechanism_parameters_hf_array[hf_index].param_name) == 0) {
switch (sec_mechanism_parameters_hf_array[hf_index].para_type) {
case MECH_PARA_STRING:
proto_tree_add_item(tree, *sec_mechanism_parameters_hf_array[hf_index].hf_item, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1,
ENC_UTF_8);
break;
case MECH_PARA_UINT:
if (!value) {
proto_tree_add_expert(tree, pinfo, &ei_sip_sipsec_malformed,
tvb, current_offset, -1);
} else {
guint32 semi_para;
semi_para = (guint32)strtoul(value, NULL, 10);
proto_tree_add_uint(tree, *sec_mechanism_parameters_hf_array[hf_index].hf_item, tvb,
equals_offset+1, semi_colon_offset-equals_offset-1, semi_para);
}
break;
default:
break;
}
break;
}
hf_index++;
}
else{
if (!sec_mechanism_parameters_hf_array[hf_index].param_name) {
proto_tree_add_format_text(tree, tvb, current_offset, length);
}
current_offset = semi_colon_offset+1;
}