\ud83d\udc49\ud83c\udffb \uc544\ub798\ub294 amf0.cpp \ud30c\uc77c\uc774 \ud568\uc218\uc5d0 \ub300\ud55c \uc124\uba85\uc785\ub2c8\ub2e4.
Below is a description of the functions in the amf0.cpp file.<\/p>\n\n\n\n
\ud83d\udc49\ud83c\udffb \ucf54\ub4dc \uc124\uba85 \/ Code Explanation<\/p>\n\n\n\n
\u2714\ufe0f void Amf0::parse_object(const std::vector& buf, size_t& pos) { } <\/p>\n\n\n\n
— RTMP \ud328\ud0b7 \uc548\uc5d0 \ub4e4\uc5b4\uc788\ub294 AMF0 Object\ub97c \uc77d\uc5b4\uc11c \ubc84\ud37c \ud3ec\uc778\ud130\ub97c \ub2e4\uc74c \ud544\ub4dc\ub85c \uc62e\uae30\ub294 \uc6a9\ub3c4\uc785\ub2c8\ub2e4.
It is used to read an AMF0 object contained within an RTMP packet and advance the buffer pointer to the next field.<\/p>\n\n\n\n
— \uc608\uc2dc\ub370\uc774\ud130(\ubc84\ud37c \ud398\uc774\ub85c\ub4dc)
Example data (buffer payload)<\/p>\n\n\n\n
03 | 00 03 'a' 'p' 'p' | 02 00 04 'l' 'i' 'v' 'e' | 00 05 'f' 'p' 'a' 'd' | 01 00 | 00 00 09<\/code><\/pre>\n\n\n\npos 0 : 03 \/\/ AMF0 Object \uc2dc\uc791 \/ AMF0 Object Start\npos 1-2: 00 03 \/\/ key \uae38\uc774 3 \/ Key length 3\npos 3-5: 61 70 70 \/\/ 'a' 'p' 'p'\npos 6 : 02 \/\/ value \ud0c0\uc785 = string \/ value type = string\npos 7-8: 00 04 \/\/ string \uae38\uc774 4 \/ String length 4\npos 9-12: 6c 69 76 65 \/\/ 'l' 'i' 'v' 'e'\npos13-14: 00 05 \/\/ key \uae38\uc774 5 \/ Key length 5\npos15-19: 66 70 61 64 \/\/ 'f' 'p' 'a' 'd'\npos20 : 01 \/\/ value \ud0c0\uc785 = boolean \/ value type = boolean\npos21 : 00 \/\/ false\npos22-23: 00 00 \/\/ key \uae38\uc774 0 \/ key length 0\npos24 : 09 \/\/ object end<\/code><\/pre>\n\n\n\n— pos \uac12\uc740 0\uc778 \uacbd\uc6b0\ub85c \ud569\ub2c8\ub2e4.
Assume the value of ‘pos’ is 0.<\/p>\n\n\n\n
— 0x03\uc73c\ub85c\uc2dc\uc791\ud558\ub294\uc9c0 \ud655\uc778
Check if it starts with 0x03.<\/p>\n\n\n\n
if (pos >= buf.size() || buf[pos]!= 0x03) return;<\/code><\/pre>\n\n\n\n— 0x03\uc704\uce58 \ub2e4\uc74c\uc73c\ub85c \ud3ec\uc778\ud130\uc774\ub3d9,1,pos\uae30\ubcf8\uac12 = 0
0x03 Move pointer to position; default pos = 0.<\/p>\n\n\n\n
pos++;<\/code><\/pre>\n\n\n\n— while (3 < 25) \uc778\uacbd\uc6b0 \uc785\ub2c8\ub2e4.
This is the case where while (3 < 25)<\/code> applies.<\/p>\n\n\n\nwhile (pos + 2 < buf.size()) { ...} <\/code><\/pre>\n\n\n\n— buf[pos]\ub97c \uc0c1\uc704\ubc14\uc774\ud2b8\ub85c \uc774\ub3d9\ud558\uace0 \ud558\uc704\ub294 8\ube44\ud2b8( 1\ubc14\uc774\ud2b8 \ub85c \ucc44\uc6c1\ub2c8\ub2e4.(1\ubc14\uc774\ud2b8 \uc0ac\uc6a9\uc2dc 16\uc9c4\uc218\ub294 \ub450\uc790\ub9ac \uc0ac\uc6a9\ud569\ub2c8\ub2e4.)
Move buf[pos]<\/code> to the high byte and fill the low byte with 8 bits (1 byte). (Two hexadecimal digits are used for a single byte.)<\/p>\n\n\n\n— pos=1 : buf[1] = 0x00,pos=2 : buf[2] = 0x03,len = (0x00 << 8) | 0x03 = 0x0000 | 0x0003 = 3<\/p>\n\n\n\n
pos=1 : buf[1] = 0x00\npos=2 : buf[2] = 0x03\nlen = (0x00 << 8) | 0x03 = 0x0000 | 0x0003 = 3<\/code><\/pre>\n\n\n\n— \uc5ec\uae30\uc11c pos=3 \uc774 \ub429\ub2c8\ub2e4.
Here, pos becomes 3.<\/p>\n\n\n\n
pos += 2;<\/code><\/pre>\n\n\n\n— if( 3 < 25 && buf[3] == 0x09)\uc774\uba70 ,0x09\ub294 \ubc84\ud37c\ub05d\uc744 \uc758\ubbf8\ud569\ub2c8\ub2e4.
If 3 < 25 && buf[3] == 0x09<\/code> is true, then 0x09<\/code> signifies the end of the buffer.<\/p>\n\n\n\n if (pos < buf.size() && buf[pos] == 0x09) { pos++; break; }<\/code><\/pre>\n\n\n\n— if(3 + 3) > 25 return;\uc774 \ub429\ub2c8\ub2e4.
It becomes if(3 + 3) > 25 return;<\/code>.<\/p>\n\n\n\nif (pos + len > buf.size()) return;<\/code><\/pre>\n\n\n\n— vector\uc5d0\uc11c \uc9c0\uc815\ud55c \uad6c\uac04\ub9cc\ud07c \uc798\ub77c\uc11c std::string\uc73c\ub85c \ubcf5\uc0ac\ud558\ub294 \uc0dd\uc131\uc790\uc785\ub2c8\ub2e4.
This is a constructor that extracts a specified range from a vector and copies it into an std::string.<\/p>\n\n\n\n
— string key(3,6)\uc774\ub418\uace0 ,6\uc55e\uae4c\uc9c0\ub9cc \uc0ac\uc6a9\ud558\ubbc0\ub85c 6\uc740 \ud3ec\ud568\ub418\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.
The string key is (3, 6); since it is used only up to the position before 6, the value 6 is not included.<\/p>\n\n\n\n
— \uadf8\ub7ec\uba74 \ubc84\ud37c\uc5d0\uc11c app\uc774\ub780 \uae00\uc790\ub97c \ucd94\ucd9c\ud558\uac8c\ub429\ub2c8\ub2e4.
Then, the string “app” is extracted from the buffer.<\/p>\n\n\n\n
std::string key(buf.begin() + pos, buf.begin() + pos + len);<\/code><\/pre>\n\n\n\n— pos\uac00 3\uc774\uace0 len\uc774\ub2c8\uae4c \uacb0\uad6d pos\ub294 6\uc774 \ub429\ub2c8\ub2e4.
Since pos is 3 and we add len, pos ultimately becomes 6.<\/p>\n\n\n\n
pos += len;<\/code><\/pre>\n\n\n\n— skip_value(buf, 6) \uc774 \uc2e4\ud589\ub429\ub2c8\ub2e4.
skip_value(buf, 6)<\/code> is executed.<\/p>\n\n\n\nskip_value(buf, pos);<\/code><\/pre>\n\n\n\n
\n\n\n\n\u2714\ufe0f static void skip_value(const std::vector& buf, size_t& pos) { … }<\/p>\n\n\n\n
— parse_object\uc5d0\uc11c pos\ucd08\uae30 \uac12\uc774 0\uc778 \uacbd\uc6b0 \uc5ec\uae30\ub294 6\uc774 \ub429\ub2c8\ub2e4.
If the initial value of pos<\/code> in parse_object<\/code> is 0, it becomes 6 here.<\/p>\n\n\n\n— pos 0 \u2192 03,pos 6 \u2192 02,pos 19 \u2192 01 \uc774 \uc138\uacf3\uc678\uc5d0\ub294 \ub370\uc774\ud130\ub97c \uc77d\ub294 \ubd80\ubd84\uc774 \uc5c6\uc2b5\ub2c8\ub2e4.
There are no data-reading points other than these three locations: pos 0 \u2192 03, pos 6 \u2192 02, and pos 19 \u2192 01.<\/p>\n\n\n\n
— \uc544\ub798\uc758 case\uc5d0\uc11c\ub3c4 \ub098\uba38\uc9c0\ub294 \uc801\uc6a9 \ub418\uc9c0 \uc54a\uc2b5\ub2c8\ub2e4.
The rest do not apply in the case below either.<\/p>\n\n\n\n
if (pos >= buf.size()) return;\n uint8_t t = buf[pos];<\/code><\/pre>\n\n\n\n— \uc22b\uc790\uc778 \uacbd\uc6b0\ub97c \uc758\ubbf8\ud558\uba70 \ud604\uc7ac\ub294 \ud574\ub2f9\ud558\ub294 \ubd80\ubd84\uc774 \uc5c6\uc2b5\ub2c8\ub2e4.(pos\uac00 00\ub97c \uc77d\uc744 \uc77c\uc774 \uc5c6\uc74c)
This refers to the case where the value is a number; currently, there is no corresponding instance (as pos<\/code> never reads 00<\/code>).<\/p>\n\n\n\ncase 0x00: pos += 9; break;<\/code><\/pre>\n\n\n\n— case 0x01: boolean<-pos+=2->\uc778\uac74 \uadf8\ub0e5 AMF0 \uc2a4\ud399\uc5d0 \ub530\ub77c \uc815\ud574\uc9c4\uac83 \uc785\ub2c8\ub2e4.
The case 0x01: boolean<-pos+=2-><\/code> part is simply determined by the AMF0 specification.<\/p>\n\n\n\n— buf[20] \uc778\uacbd\uc6b0 pos\ub294 22\uac00\ub418\uba70 \uac12\uc740 00\uac00 \ub429\ub2c8\ub2e4.
If buf[20] is used, pos becomes 22 and the value becomes 00.<\/p>\n\n\n\n
case 0x01: pos += 2; break;<\/code><\/pre>\n\n\n\n— buf[6], pos=6<\/p>\n\n\n\n
case 0x02: { size_t tmp=pos; Amf0::parse_string(buf, tmp); pos=tmp; break; }<\/code><\/pre>\n\n\n\n— pos = 0 \uc778\uacbd\uc6b0
When pos is 0<\/p>\n\n\n\n
— Amf0::parse_object(buf, 6); \uac12\uc774 \ub300\uc785\ub429\ub2c8\ub2e4.
The value Amf0::parse_object(buf, 6)<\/code> is assigned.<\/p>\n\n\n\n— \uc704\uc758 \ud568\uc218\ub0b4\uc5d0\uc11c std::string str(buf.begin() + pos, buf.begin() + pos + len); \uc774 \ubd80\ubd84\uc73c\ub85c \ubb38\uc790\uc5f4\uc744 \ucd94\ucd9c\ud569\ub2c8\ub2e4.
Within the function above, the string is extracted using this part: std::string str(buf.begin() + pos, buf.begin() + pos + len);<\/code>.<\/p>\n\n\n\n— std::string str(9,13); \uc774\ub807\uac8c \uac12\uc774 \ub300\uc785\ub429\ub2c8\ub2e4.
The value is assigned like this: std::string str(9,13);<\/code>.<\/p>\n\n\n\n— \uc2e4\uc81c\ub85c\ucd94\ucd9c\ub418\ub294 \ubb38\uc790\uc5f4\uc740 live\uc785\ub2c8\ub2e4.
The string actually extracted is “live”.<\/p>\n\n\n\n
case 0x03: { Amf0::parse_object(buf, pos); break; }<\/code><\/pre>\n\n\n\n— null,undefinded\uc778 \uacbd\uc6b0 \uc785\ub2c8\ub2e4.
This applies to cases where the value is null<\/code> or undefined<\/code>.<\/p>\n\n\n\n case 0x05: case 0x06: pos += 1; break; <\/code><\/pre>\n\n\n\n— ECMA array \ubd80\ubd84\uc73c\ub85c \ubc84\ud37c\uc5d0 \uac12\uc774 \uc5c6\uc2b5\ub2c8\ub2e4. \ucd94\ud6c4\uc5d0 \ucd94\uac00\ub420 \uae30\ub2a5\uc785\ub2c8\ub2e4.
There are no values \u200b\u200bin the buffer for the ECMA array section; this is a feature to be added later.<\/p>\n\n\n\n
while (pos + 2 < buf.size()) {\n uint16_t len = (buf[pos] << 8) | buf[pos+1];\n pos += 2;\n if (len == 0 && pos < buf.size() && buf[pos] == 0x09) { pos++; break; }\n pos += len;\n skip_value(buf, pos);\n}<\/code><\/pre>\n\n\n\n<\/p>\n","protected":false},"excerpt":{"rendered":"
\ud83d\udc49\ud83c\udffb \uc544\ub798\ub294 amf0.cpp \ud30c\uc77c\uc774 \ud568\uc218\uc5d0 \ub300\ud55c \uc124\uba85\uc785\ub2c8\ub2e4.Below is a description of the functions in the amf0.cpp file. \ud83d\udc49\ud83c\udffb \ucf54\ub4dc \uc124\uba85 \/ Code Explanation \u2714\ufe0f void Amf0::parse_object(const std::vector& buf, size_t& pos) { } — RTMP \ud328\ud0b7 \uc548\uc5d0 \ub4e4\uc5b4\uc788\ub294 AMF0 Object\ub97c \uc77d\uc5b4\uc11c \ubc84\ud37c \ud3ec\uc778\ud130\ub97c \ub2e4\uc74c \ud544\ub4dc\ub85c \uc62e\uae30\ub294 \uc6a9\ub3c4\uc785\ub2c8\ub2e4.It is used to read an AMF0 object contained within […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,1],"tags":[],"class_list":["post-6184","post","type-post","status-publish","format-standard","hentry","category-cpp","category-uncategorized","missing-thumbnail"],"_links":{"self":[{"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/6184","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=6184"}],"version-history":[{"count":33,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/6184\/revisions"}],"predecessor-version":[{"id":6217,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/6184\/revisions\/6217"}],"wp:attachment":[{"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=6184"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/categories?post=6184"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.freelifemakers.org\/wordpress\/index.php\/wp-json\/wp\/v2\/tags?post=6184"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}