可以给出详细的注释吗 。包括原理，参数等等，我是初学者，/
******************************************************************************
*
* Copyright
(c
) 2023 TP-LINK Technologies CO.,LTD.
* All rights reserved.
*
* FILE NAME : at_utils.c
* VERSION : 1.0
* DESCRIPTION : AT命令解析工具.
*
* AUTHOR : tangqilin
(tangqilin@tp-link.com.hk
)
* CREATE DATE : 03/25/2023
*
* HISTORY :
* 01 03/25/2023 Tang Qilin Create.
*
******************************************************************************/
#include "at_utils.h"
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <sys/socket.h>
/
**
* Starts tokenizing an AT response string
* returns -1 if this is not a valid response string, 0 on success.
* updates
*p_cur with current position
*/
S32 at_tok_start
(char **p_cur
)
{
if
(*p_cur == NULL
)
{
return -1;
}
// skip prefix
// consume "^[^:]:"
*p_cur = strchr
(*p_cur, ':'
);
if
(*p_cur == NULL
)
{
return -1;
}
(*p_cur
)++;
return 0;
}
/
** return 1 if line starts with prefix, 0 if it does not
*/
S32 strStarwith
(const
char *line, const
char *prefix
)
{
for
( ;
*line != '\0' &&
*prefix != '\0' ; line++, prefix++
)
{
if
(*line !=
*prefix
)
{
return 0;
}
}
return
*prefix == '\0';
}
S32 at_tok_nextlonglong
(char **p_cur, long long
*p_out
)
{
return at_tok_nextlonglong_base
(p_cur, p_out, 10, 0
);
}
S32 at_tok_nextlonglong_base
(char **p_cur, long long
*p_out,
int base,
int uns
)
{
char *ret;
if
(*p_cur == NULL
)
{
return -1;
}
ret = nextTok
(p_cur
);
if
(ret == NULL
)
{
return -1;
}else
{
long long l;
char *end;
if
(uns
)
{
l = strtoull
(ret, &end, base
);
}else
{
l = strtoll
(ret, &end, base
);
}
*p_out =
(long long
)l;
if
(end == ret
)
{
return -1;
}
}
return 0;
}
/
**
* Parses the next base 10
integer in the AT response line
* and places it in
*p_out
* returns 0 on success and -1 on fail
* updates
*p_cur
*/
S32 at_tok_next
int(char **p_cur,
int *p_out
)
{
return at_tok_next
int_base
(p_cur, p_out, 10, 0
);
}
/
**
* Parses the next
integer in the AT response line and places it in
*p_out
* returns 0 on success and -1 on fail
* updates
*p_cur
* "base" is the same as the base param in strtol
*/
S32 at_tok_next
int_base
(char **p_cur,
int *p_out,
int base,
int uns
)
{
char *ret;
if
(*p_cur == NULL
)
{
return -1;
}
ret = nextTok
(p_cur
);
if
(ret == NULL
)
{
return -1;
}else
{
long l;
char *end;
if
(uns
)
{
l = strtoul
(ret, &end, base
);
}else
{
l = strtol
(ret, &end, base
);
}
*p_out =
(int)l;
if
(end == ret
)
{
return -1;
}
}
return 0;
}
void skipWhiteSpace
(char **p_cur
)
{
if
(*p_cur == NULL
)return;
while
(**p_cur != '\0' && isspace
(**p_cur
))
{
(*p_cur
)++;
}
}
/
**
* Parses the next base 16
integer in the AT response line
* and places it in
*p_out
* returns 0 on success and -1 on fail
* updates
*p_cur
*/
S32 at_tok_nexthex
int(char** p_cur,
int* p_out
)
{
return at_tok_next
int_base
(p_cur, p_out, 16, 1
);
}
S32 at_tok_nextbool
(char** p_cur,
char* p_out
)
{
int ret;
int result;
ret = at_tok_next
int(p_cur, &result
);
if
(ret < 0
) {
return -1;
}
// booleans should be 0 or 1
if
(!
(result == 0 || result == 1
)) {
return -1;
}
if
(p_out != NULL
) {
*p_out =
(char)result;
}
return ret;
}
/
** returns 1 on "has more tokens" and 0 if no
*/
S32 at_tok_hasmore
(char** p_cur
)
{
return !
(*p_cur == NULL ||
**p_cur == '\0'
);
}
S32 at_tok_count
(const
char* in_line
)
{
int commas = 0;
const
char* p;
if
(!in_line
)
return 0;
for
(p = in_line;
*p != '\0'; p++
) {
if
(*p == ','
) commas++;
}
return commas;
}
//fmt: d ~
int, x ~ hex
int, b ~ bool, s ~ str
S32 at_tok_scanf
(const
char* in_line, const
char* fmt, ...
)
{
int n = 0;
int err;
va_list ap;
const
char* p = fmt;
void
* d;
void
* dump;
static
char s_line[1024];
char* line = s_line;
if
(!in_line
)
return 0;
strncpy
(s_line, in_line, sizeof
(s_line
));
va_start
(ap, fmt
);
err = at_tok_start
(&line
);
if
(err < 0
) goto error;
for
(;
*p; p++
) {
if
(*p == ',' ||
*p == ' '
)
continue;
if
(*p != '%'
) {
goto error;
}
p++;
d = va_arg
(ap, void
*);
if
(!d
)
d = &dump;
if
(!at_tok_hasmore
(&line
))
break;
if
(*line == '-' &&
*(line + 1
) == ','
) {
line += 2;
n++;
if
(*p == 'd'
)
* (int*)d = -1;
continue;
}
switch
(*p
) {
case 'd':
err = at_tok_next
int(&line,
(int*)d
);
if
(err < 0
) goto error;
break;
case 'x':
err = at_tok_nexthex
int(&line,
(int*)d
);
if
(err < 0
) goto error;
break;
case 'b':
err = at_tok_nextbool
(&line,
(char*)d
);
if
(err < 0
) goto error;
break;
case 's':
err = at_tok_nextstr
(&line,
(char**)d
); //if strdup
(line
), here return free
memory to caller
if
(err < 0
) goto error;
break;
case 'l':
err = at_tok_nextlonglong
(&line,
(long long
*)d
);
if
(err < 0
) goto error;
break;
default:
goto error;
break;
}
n++;
}
va_end
(ap
);
error:
//free
(line
);
return n;
}
void skipNextComma
(char **p_cur
)
{
if
(*p_cur == NULL
) return;
while
(**p_cur != '\0' &&
**p_cur != ','
)
{
(*p_cur
)++;
}
if
(**p_cur == ','
)
{
(*p_cur
)++;
}
}
char *nextTok
(char **p_cur
)
{
char *ret = NULL;
skipWhiteSpace
(p_cur
);
if
(*p_cur == NULL
)
{
ret = NULL;
}
else if
(**p_cur == '"'
)
{
(*p_cur
)++;
ret = strsep
(p_cur, "\""
);
skipNextComma
(p_cur
);
}else
{
ret = strsep
(p_cur, ","
);
}
return ret;
}
S32 at_tok_nextstr
(char **p_cur,
char **p_out
)
{
if
(*p_cur == NULL
)
{
return -1;
}
*p_out = nextTok
(p_cur
);
return 0;
}
char* skipLFCR
(char *str
)
{
char *p = NULL;
int len = 0;
int start = 0;
if
(NULL == str
)
{
return NULL;
}
p = str;
len = strlen
(str
);
while
(start < len
)
{
if
('\r' ==
*p || '\n' ==
*p
)
{
p++;
start++;
}
else
{
break;
}
}
if
(start == len
)
{
return NULL;
}
return p;
}
/
*
dot
num
ipv4 3
ipv4+mask 7
ipv6 15
ipv6+mask 31
*/
int get_ip_mask
(char *ip_and_mask,
char* ip,
char* mask
)
{
int len = 0;
int i = 0;
int dot_
num = 0;
if
(ip_and_mask == NULL || ip == NULL || mask == NULL
)
{
return -1;
}
len = strlen
(ip_and_mask
);
for
(i = 0; i < len; i++
)
{
if
(ip_and_mask[i] == '.'
)
{
dot_
num++;
}
}
if
(dot_
num == 31
)
{
dot_
num = 0;
for
(i = 0; i < len; i++
)
{
if
(ip_and_mask[i] == '.'
)
{
dot_
num++;
if
(dot_
num == 16
)
{
break;
}
}
}
memcpy
(ip, ip_and_mask, i
);
memcpy
(mask, &ip_and_mask[i+1], len-i-1
);
}
else if
(dot_
num == 15
)
{
memcpy
(ip, ip_and_mask, strlen
(ip_and_mask
));
}
else if
(dot_
num == 7
)
{
dot_
num = 0;
for
(i = 0; i < len; i++
)
{
if
(ip_and_mask[i] == '.'
)
{
dot_
num ++;
if
(dot_
num == 4
)
{
break;
}
}
}
memcpy
(ip, ip_and_mask, i
);
memcpy
(mask, &ip_and_mask[i+1], len-i-1
);
}
else if
(dot_
num == 3
)
{
memcpy
(ip, ip_and_mask, strlen
(ip_and_mask
));
}
else
{
return -1;
}
return 0;
}
int is_ipv4
(char *ip
)
{
int len = 0;
int i = 0;
char *str = NULL;
int dot_
num = 0;
if
(ip == NULL
)
{
return -1;
}
str = ip;
for
(i = 0, len = strlen
(str
); i < len; i++
)
{
if
(str[i] == '.'
)
{
dot_
num ++;
}
}
if
(dot_
num == 3
)
{
return 1;
}
else if
(dot_
num == 15
)
{
return 0;
}
else
{
return -1;
}
}
int get_ipv4_gw
(char * ip,
char * gw
)
{
int len =0;
int i =0;
char * str = NULL;
int dot_
num = 0;
if
(ip == NULL
)
{
return -1;
}
str = ip;
for
( i = 0, len = strlen
(str
); i < len; i++
)
{
if
(str[i]=='.'
)
{
dot_
num++;
if
(dot_
num == 3
)
{
i++;
break;
}
}
}
if
(dot_
num != 3
)
{
return -1;
}
int last_
num = atoi
(str+i
);
if
(last_
num < 0 || last_
num > 255
)
{
return -1;
}
memcpy
(gw, str, len
);
memset
(gw+i, 0, 4
);
/
* 如果获取的IP地址最后一字节为255，则将网关的最后一字节设置为1
*/
if
(255 - last_
num == 0
)
{
snpr
intf
(gw+i, 4, "%d", 1
);
}else
{
snpr
intf
(gw+i, 4, "%d", 255-last_
num);
}
return 0;
}
#ifdef CONFIG_IPV6
int charCountInStr
(const
char* str,
char ch
)
{
int i;
int num = 0;
for
(i=0; str[i] != '\0'; i++
)
{
if
(str[i] == ch
)
{
num ++;
}
}
return
num;
}
/
* return 1 success
* return 0 failed
*/
int convertDotNotation2Ipv4U
int (const
char *source, unsigned
int *addr, unsigned
int *mask
)
{
int i;
int count =
charCountInStr
(source, '.'
);
char * end;
for
(i = 0; i <= count; i++
)
{
if
(i < 4
)
{
addr[0] |= strtoul
(source, &end, 10
) << i
* 8;
}
else if
(i < 8
)
{
mask[0] |= strtoul
(source, &end, 10
) <<
(i - 4
) * 8;
}
if
(i == count ||
*end == '\0'
)
{
//RLOGI
(convertDotNotation2Ipv4U
int, "%s, count=%d", __FUNCTION__, count
);
//LOG_I
( "%s, count=%d", "convertDotNotation2Ipv6U
int", count
);
return 1;
}
else if
(*end != '.'
)
{
return 0;
}
source = end + 1;
}
return 0;
}
/
* return 1 success
* return 0 failed
*/
int convertDotNotation2Ipv6U
int (const
char *source, unsigned
int *addr, unsigned
int *mask
)
{
int i;
int count =
charCountInStr
(source, '.'
);
char * end;
for
(i = 0; i <= count; i++
)
{
if
(i < 4
)
{
addr[0] |= strtoul
(source, &end, 10
) << i
* 8;
}
else if
(i < 8
)
{
addr[1] |= strtoul
(source, &end, 10
) <<
(i - 4
) * 8;
}
else if
(i < 12
)
{
addr[2] |= strtoul
(source, &end, 10
) <<
(i - 8
) * 8;
}
else if
(i < 16
)
{
addr[3] |= strtoul
(source, &end, 10
) <<
(i - 12
) * 8;
}
else if
(i < 20
)
{
mask[0] |= strtoul
(source, &end, 10
) <<
(i - 16
) * 8;
}
else if
(i < 24
)
{
mask[1] |= strtoul
(source, &end, 10
) <<
(i - 20
) * 8;
}
else if
(i < 28
)
{
mask[2] |= strtoul
(source, &end, 10
) <<
(i - 24
) * 8;
}
else if
(i < 32
)
{
mask[3] |= strtoul
(source, &end, 10
) <<
(i - 28
) * 8;
}
if
(i == count ||
*end == '\0'
)
{
//RLOGI
(convertDotNotation2Ipv6U
int, "%s, count=%d", __FUNCTION__, count
);
//LOG_I
( "%s, count=%d", "convertDotNotation2Ipv6U
int", count
);
return 1;
}
else if
(*end != '.'
)
{
return 0;
}
source = end + 1;
}
return 0;
}
/
* return 1 success
* return 0 failed
*/
int convertDotNotation2IpU
int(int af, const
char *source, unsigned
int *addr, unsigned
int *mask
)
{
if
(af == AF_INET
)
{
return convertDotNotation2Ipv4U
int(source, addr, mask
);
}
else
{
return convertDotNotation2Ipv6U
int(source, addr, mask
);
}
}
/
* return address family
*/
int convertDotNotation2IpString
(const
char *source,
char *ipaddress,
char *ipmask
)
{
unsigned
int addr[4];
unsigned
int mask[4];
int af;
int ret;
int count =
charCountInStr
(source, '.'
);
memset
(addr, 0, sizeof
(addr
));
memset
(mask, 0, sizeof
(mask
));
if
(count < 8
)
{
af = AF_INET;
}
else if
(count < 32
)
{
af = AF_INET6;
}
else
{
return -1;
}
ret = convertDotNotation2IpU
int(af, source, addr, mask
);
if
(ret > 0
)
{
if
(ipaddress != NULL
)
{
inet_ntop
(af, addr, ipaddress, INET6_ADDRSTRLEN
);
}
if
(ipmask != NULL
)
{
inet_ntop
(af, mask, ipmask,INET6_ADDRSTRLEN
);
}
}
else
{
pr
intf
("%s, covert failed", "convertDotNotation2IpString"
);
return -1;
}
return af;
}
#endif
本文通过C语言中的一段内存分配代码及其反汇编过程，详细解析了如何使用malloc进行内存分配，并探讨了指针参数在函数调用过程中是如何被处理的。指出在函数内部修改指针本身不会影响外部调用者，但可以通过返回值来更新指针所指向的内容。
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