`nx_yt_nsolve.nx` source

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1// nx_yt_nsolve.nx -- the YouTube n-THROTTLE SOLVER. Modern googlevideo URLs carry an &n=<token> param; if you
2// fetch with the RAW n, the CDN throttles you to ~50KB/s (broken/slow downloads). base.js ships a JS function
3// that transforms n -> n' ; requesting with n' gives full speed. That function is JS (array/char scrambling),
4// exactly the class our engine already runs (see nx_js_ytsig_gate: split->transform->join). So the solver is:
5// (1) EXTRACT the named function from base.js text -- brace-balanced + STRING-AWARE so literals with { } " ' in
6// the body don't truncate it; (2) BUILD a self-contained runnable script (def + call); (3) RUN it via
7// js_run_source and read the string result. This turns an extracted throttled URL into a FAST one, sovereignly
8// (our own JS engine -- no Node, no remote). The function NAME + its helper-array location are themselves
9// site-shape patterns -> feed the self-healing table (nx_extract_heal) when YouTube reshapes base.js. license_tier: ORIGINAL
10import "nx_syscalls.nx"
11import "nx_media_signal.nx"     // xt_find
12import "nx_js_eval.nx"          // js_run_source + VAL_STR + ev_str_bytes/len
13
14func ns_apps(dst: *u8, off: i64, s: *u8) -> i64 { var i: i64=0; while s[i]!=(0 as u8) { dst[off]=s[i]; off=off+1; i=i+1 } return off }
15func ns_appb(dst: *u8, off: i64, src: *u8, from: i64, n: i64) -> i64 { var i: i64=0; while i<n { dst[off]=src[from+i]; off=off+1; i=i+1 } return off }
16
17// skip a JS string literal starting at the opening quote `q` (34=" 39='); returns index AFTER the closing quote,
18// honoring backslash escapes. Keeps brace-counting from being fooled by { } inside "..." / '...'.
19func ns_skip_str(js: *u8, jl: i64, start: i64, q: i64) -> i64 {
20    var j: i64 = start + 1
21    var go: i64 = 1
22    while go == 1 {
23        if j >= jl { go = 0 }
24        else { let c: i64 = js[j] & 0xff
25            if c == 92 { j = j + 2 }
26            else { if c == q { j = j + 1; go = 0 } else { j = j + 1 } } }
27    }
28    return j
29}
30
31// find the START of the function named `name` in base.js: assignment form `name=function` OR declaration form
32// `function name`. Sets isdecl[0] (0=assignment, 1=declaration). Returns start index or -1.
33func ns_find_fn_start(js: *u8, jl: i64, name: *u8, namelen: i64, isdecl: *i64) -> i64 {
34    let nd: *u8 = sys_mmap(512)
35    // assignment: name + "=function"
36    var o: i64 = ns_appb(nd, 0, name, 0, namelen)
37    o = ns_apps(nd, o, "=function" as *u8)
38    let p: i64 = xt_find(js, jl, nd, o, 0)
39    if p >= 0 { isdecl[0] = 0; return p }
40    // declaration: "function " + name
41    o = ns_apps(nd, 0, "function " as *u8)
42    o = ns_appb(nd, o, name, 0, namelen)
43    let q: i64 = xt_find(js, jl, nd, o, 0)
44    if q >= 0 { isdecl[0] = 1; return q }
45    return 0 - 1
46}
47
48// from `from`, find the first `{`, then return the index just AFTER its matching `}` (string-aware). -1 if none.
49func ns_body_end(js: *u8, jl: i64, from: i64) -> i64 {
50    var i: i64 = from
51    var found: i64 = 0 - 1
52    while i < jl { if (js[i]&0xff) == 123 { found = i; i = jl } else { i = i + 1 } }
53    if found < 0 { return 0 - 1 }
54    var depth: i64 = 0
55    var j: i64 = found
56    var end: i64 = 0 - 1
57    var go: i64 = 1
58    while go == 1 {
59        if j >= jl { go = 0 }
60        else {
61            let c: i64 = js[j] & 0xff
62            if c == 34 { j = ns_skip_str(js, jl, j, 34) }
63            else { if c == 39 { j = ns_skip_str(js, jl, j, 39) }
64            else {
65                if c == 123 { depth = depth + 1 }
66                if c == 125 { depth = depth - 1 }
67                if c == 125 { if depth == 0 { end = j + 1; go = 0 } }
68                j = j + 1
69            } }
70        }
71    }
72    return end
73}
74
75// BUILD a self-contained runnable script that defines the extracted function and CALLS it with `arg`. For the
76// assignment form we prepend `var ` so the name is bound; the last expression is the call (its value = result).
77// Returns script length in `out`, or a negative extract error.
78func ns_build_script(js: *u8, jl: i64, name: *u8, namelen: i64, arg: *u8, arglen: i64, out: *u8, cap: i64) -> i64 {
79    let isdecl: *i64 = sys_mmap(8) as *i64
80    let start: i64 = ns_find_fn_start(js, jl, name, namelen, isdecl)
81    if start < 0 { return 0 - 1 }
82    let end: i64 = ns_body_end(js, jl, start)
83    if end < 0 { return 0 - 2 }
84    var o: i64 = 0
85    if isdecl[0] == 0 { o = ns_apps(out, o, "var " as *u8) }
86    o = ns_appb(out, o, js, start, end - start)
87    o = ns_apps(out, o, ";" as *u8)
88    o = ns_appb(out, o, name, 0, namelen)
89    o = ns_apps(out, o, "(\"" as *u8)
90    o = ns_appb(out, o, arg, 0, arglen)
91    o = ns_apps(out, o, "\")" as *u8)
92    out[o] = 0 as u8
93    return o
94}
95
96// SOLVE: extract the n-function `name` from base.js, run it on `arg` through our JS engine, write the transformed
97// string to `out`. Returns the result length, or a negative error (-1/-2 extract, -3 run, -4 non-string result).
98func ns_solve(js: *u8, jl: i64, name: *u8, namelen: i64, arg: *u8, arglen: i64, out: *u8, cap: i64) -> i64 {
99    let script: *u8 = sys_mmap(1048576)
100    let slen: i64 = ns_build_script(js, jl, name, namelen, arg, arglen, script, 1048576)
101    if slen < 0 { return slen }
102    let res: *i64 = sys_mmap(16) as *i64
103    if js_run_source(script, slen, res) != 0 { return 0 - 3 }
104    if res[0] != VAL_STR { return 0 - 4 }
105    let srec: *i64 = (res[1]) as *i64
106    let sb: *u8 = ev_str_bytes(srec); let sl: i64 = ev_str_len(srec)
107    var i: i64 = 0
108    while i < sl { if i < (cap - 1) { out[i] = sb[i] } i = i + 1 }
109    out[sl] = 0 as u8
110    return sl
111}
nx_yt_nsolve.nx source

`nx_yt_nsolve.nx` source
