feat(http): implement URI percent decoding

core/libs/prx/libSceHttp/src/Uri.cpp

@@ -1,4 +1,5 @@
 #include <cctype>
+#include <charconv>
 #include <cstdint>
 #include <cstddef>
 #include <cstring>
@@ -197,6 +198,26 @@ int APS5_VABI sceHttpUriEscape(char* out, size_t* require, size_t prepare, const
     return copyOut(escaped, out, require, prepare);
 }
 
+int APS5_VABI sceHttpUriUnescape(char* out, size_t* require, size_t prepare, const char* in) {
+    if (!in) return ERROR_INVALID_VALUE;
+
+    const std::string_view input(in);
+    std::string decoded;
+    for (size_t i = 0; i < input.size(); ++i) {
+        if (input[i] == '%' && input.size() - i >= 3) {
+            unsigned int value = 0;
+            const auto result = std::from_chars(input.data() + i + 1, input.data() + i + 3, value, 16);
+            if (result.ec == std::errc{} && result.ptr == input.data() + i + 3) {
+                decoded.push_back(static_cast<char>(value));
+                i += 2;
+                continue;
+            }
+        }
+        decoded.push_back(input[i]);
+    }
+    return copyOut(decoded, out, require, prepare);
+}
+
 int APS5_VABI sceHttpUriParse(SceHttpUriElement* out, const char* src_url, void* pool, size_t* require, size_t prepare) {
     if (!src_url) return ERROR_INVALID_URL;
     const bool write = out && pool;

core/libs/tests/GuestHttp.cpp

@@ -10,6 +10,7 @@ int APS5_VABI sceHttpUriParse(SceHttpUriElement*, const char*, void*, std::size_
 int APS5_VABI sceHttpSetInflateGZIPEnabled(int, int);
 int APS5_VABI sceHttpUriBuild(char*, std::size_t*, std::size_t, const SceHttpUriElement*, std::uint32_t);
 int APS5_VABI sceHttpUriEscape(char*, std::size_t*, std::size_t, const char*);
+int APS5_VABI sceHttpUriUnescape(char*, std::size_t*, std::size_t, const char*);
 int APS5_VABI sceHttpCreateEpoll(int, HttpEpollHandle*);
 int APS5_VABI sceHttpDestroyEpoll(int, HttpEpollHandle);
 int APS5_VABI sceHttpReadData(int, void*, std::size_t);
@@ -90,6 +91,37 @@ int main() {
     Require(Equal(escaped, "a%20b%2F~%C3%A9"));
     Require(sceHttpUriEscape(escaped, nullptr, sizeof(escaped), nullptr) == invalidValue);
 
+    constexpr const char* unescapeCases[][2] = {
+        {"", ""}, {"plain+text", "plain+text"}, {"a%20b%2F~%c3%a9", "a b/~\xC3\xA9"},
+        {"%41%4a%4F%ff", "AJO\xFF"}, {"%2520", "%20"},
+        {"%", "%"}, {"%1", "%1"}, {"%1g%gg%+1%-1", "%1g%gg%+1%-1"}
+    };
+    for (const auto& row : unescapeCases) {
+        const std::size_t size = std::strlen(row[1]) + 1;
+        Require(sceHttpUriUnescape(nullptr, &required, 0, row[0]) == 0 && required == size);
+        std::memset(escaped, 'Z', sizeof(escaped));
+        Require(sceHttpUriUnescape(escaped, &required, size - 1, row[0]) == outOfMemory && required == size);
+        for (char c : escaped) Require(c == 'Z');
+        Require(sceHttpUriUnescape(escaped, nullptr, size, row[0]) == 0);
+        Require(Equal(escaped, row[1]) && escaped[size] == 'Z');
+    }
+    Require(sceHttpUriUnescape(escaped, &required, sizeof(escaped), "a%00b") == 0);
+    Require(required == 4 && std::memcmp(escaped, "a\0b", 4) == 0);
+    std::strcpy(escaped, "%41%2f%2520");
+    Require(sceHttpUriUnescape(escaped, &required, sizeof(escaped), escaped) == 0);
+    Require(Equal(escaped, "A/%20") && required == 6);
+    Require(sceHttpUriUnescape(nullptr, nullptr, 0, "valid") == 0);
+    required = 123;
+    Require(sceHttpUriUnescape(escaped, &required, sizeof(escaped), nullptr) == invalidValue);
+    Require(required == 123 && Equal(escaped, "A/%20"));
+
+    char bytes[256], encodedBytes[766], decodedBytes[256];
+    for (std::size_t i = 1; i < 256; ++i) bytes[i - 1] = static_cast<char>(i);
+    bytes[255] = '\0';
+    Require(sceHttpUriEscape(encodedBytes, nullptr, sizeof(encodedBytes), bytes) == 0);
+    Require(sceHttpUriUnescape(decodedBytes, &required, sizeof(decodedBytes), encodedBytes) == 0);
+    Require(required == sizeof(bytes) && std::memcmp(bytes, decodedBytes, sizeof(bytes)) == 0);
+
     HttpEpollHandle epoll = nullptr;
     Require(sceHttpCreateEpoll(1, nullptr) == invalidValue);
     Require(sceHttpCreateEpoll(1, &epoll) == 0 && epoll != nullptr);

docs/dev/TechnicalDebt.md

@@ -83,6 +83,7 @@ Throughout the project, every function at every stage either **does exactly what
 - [AJM Opus decoder](../../core/libs/prx/libSceAjm.native/src/Ajm.cpp) (libSceAjm.native, codec 24) - the initialize parameter layout (`u32 channels, u32 sample rate, u32`, seen as `2, 48000, 0`) and the little-endian `u16` byte count before each packet come from one title (The Smurfs Dreams); only 48000 Hz and a zero third word are accepted
 - [sceHttpParseResponseHeader](../../core/libs/prx/libSceHttp/Export.cpp) (libSceHttp) - signature follows [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/Net/Http.cs); parsing and error codes follow [shadPS4's reverse-engineered PS4 library](https://github.com/shadps4-emu/shadPS4/blob/main/src/core/libraries/network/http.cpp), not confirmed on a PS5 title or hardware. Folded values retain their line breaks and whitespace; an empty first line starts the value scan after its line feed. A consumed byte count above `INT_MAX` throws instead of wrapping.
 - [sceHttpParseStatusLine](../../core/libs/prx/libSceHttp/src/Parse.cpp) (libSceHttp) - behaviour and error codes follow the [shadPS4](https://github.com/shadps4-emu/shadPS4) reimplementation of the PS4 library, not confirmed on a PS5 title; unlike it, no byte past `lineLen` is read
+- [sceHttpUriUnescape](../../core/libs/prx/libSceHttp/src/Uri.cpp) (libSceHttp) - signature follows [SharpProspero](https://github.com/SvenGDK/SharpProspero/blob/main/src/SharpProspero/Interop/Net/Http.cs); percent decoding, invalid sequences and error codes follow [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/main/src/core/libraries/network/http.cpp), not confirmed on a PS5 title or hardware. Size includes the final NUL; malformed escapes and `+` remain unchanged, and decoding runs once.
 - [sceHttp2GetMemoryPoolStats](../../core/libs/prx/libSceHttp2/Export.cpp) (libSceHttp2) - unknown signature
 - [sceNetGetMemoryPoolStats](../../core/libs/prx/libSceNet/Export.cpp) (libSceNet) - unknown signature
 - [sceHttpSetRequestStatusCallback](../../core/libs/prx/libSceHttp/Export.cpp) (libSceHttp) - no reference implements it (shadPS4 only logs and returns 0); when the callback runs and what status it gets is unknown